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Sample records for b-value apparent diffusion-weighted

  1. Importance of b value in diffusion weighted imaging for the diagnosis of pancreatic cancer

    PubMed Central

    Hao, Jin-Gang; Wang, Jia-Ping; Gu, Ya-Lv; Lu, Ming-Liang

    2013-01-01

    AIM: To investigate the use of multi-b-value diffusion-weighted imaging in diagnosing pancreatic cancer. METHODS: We retrospectively analyzed 33 cases of pancreatic cancer and 12 cases of benign pancreatic tumors at the Second Affiliated Hospital of Kunming Medical University from December 2008 to January 2011. The demographic characteristics, clinical presentation, routine magnetic resonance imaging and diffusion weighted imaging (DWI) features with different b values were reviewed. Continuous data were expressed as mean ± SD. Comparisons between pancreatic cancer and benign pancreatic tumors were performed using the Student’s t test. A probability of P < 0.05 was considered statistically significant. RESULTS: Thirty-three patients with pancreatic cancer were identified. The mean age at diagnosis was 60 ± 5.6 years. The male: female ratio was 21:12. Twenty cases were confirmed by surgical resection and 13 by biopsy of metastases. T1 weighted images demonstrated a pancreatic head mass in 16 patients, a pancreatic body mass in 10 cases, and a pancreatic tail mass with pancreatic atrophy in 7 cases. Eight patients had hepatic metastases, 13 had invasion or envelopment of mesenteric vessels, 4 had bone metastases, and 8 had lymph node metastases. DWI demonstrated an irregular intense mass with unclear margins. Necrotic tissue demonstrated an uneven low signal. A b of 1100 s/mm2 was associated with a high intensity signal with poor anatomical delineation. A b of 700 s/mm2 was associated with apparent diffusion coefficients (ADCs) that were useful in distinguishing benign and malignant pancreatic tumors (P < 0.05). b values of 50, 350, 400, 450 and 1100 s/mm2 were associated with ADCs that did not differentiate the two tumors. CONCLUSION: Low b value images demonstrated superior anatomical details when compared to high b value images. Tumor tissue definition was high and contrast with the surrounding tissues was good. DWI was useful in diagnosing pancreatic cancer

  2. Effect of b value on monitoring therapeutic response by diffusion-weighted imaging

    PubMed Central

    Jiang, Zhao-Xia; Peng, Wei-Jun; Li, Wen-Tao; Tang, Feng; Liu, Shi-Yuan; Qu, Xu-Dong; Wang, Jian-Hua; Lu, Hong-Feng

    2008-01-01

    AIM: To explore the diffusion gradient b-factor that optimizes both apparent diffusion coefficient (ADC) measurement and contrast-to-noise (CNR) for assessing tumor response to transarterial chemoembolization (TACE) in a rabbit model. METHODS: Twelve New Zealand white rabbits bearing VX2 tumors in the liver were treated with TACE. Diffusion-weighted imaging (DWI) with various b values was performed using the same protocol before and 3 d after treatment with TACE. ADC values and CNR of each tumor pre- and post-treatment with different b factors were analyzed. Correlation between ADC values and extent of necrosis in histological specimens was analyzed by a Pearson’s correlation test. RESULTS: The quality of diffusion-weighted images diminished as the b value increased. A substantial decrease in the mean lesion-to-liver CNR was observed on both pre- and post-treatment DW images, the largest difference in CNR pre- and post-treatment was manifested at a b value of 1000 s/mm2 (P = 0.036 ). The effect of therapy on diffusion early after treatment was shown by a significant increase in ADCs (P = 0.007), especially with large b factors (≥ 600 s/mm2). The mean percentage of necrotic cells present within the tumor was 76.3%-97.5%. A significant positive correlation was found between ADC values and the extent of necrosis with all b values except for b200, a higher relative coefficient between ADC values and percentage of necrosis was found on DWI with b1000 and b2000 (P = 0.002 and 0.006, respectively). CONCLUSION: An increasing b value of up to 600 s/mm2 would increase ADC contrast pre- and post-treatment, but decrease image quality. Taking into account both CNR and ADC measurement, diffusion-weighted imaging obtained with a b value of 1000 s/mm2 is recommended for monitoring early hepatic tumor response to TACE. PMID:18855990

  3. Hypercellularity Components of Glioblastoma Identified by High b-Value Diffusion-Weighted Imaging

    SciTech Connect

    Pramanik, Priyanka P.; Parmar, Hemant A.; Mammoser, Aaron G.; Junck, Larry R.; Kim, Michelle M.; Tsien, Christina I.; Lawrence, Theodore S.; Cao, Yue

    2015-07-15

    Purpose: Use of conventional magnetic resonance imaging (MRI) for target definition may expose glioblastomas (GB) to inadequate radiation dose coverage of the nonenhanced hypercellular subvolume. This study aimed to develop a technique to identify the hypercellular components of GB by using high b-value diffusion-weighted imaging (DWI) and to investigate its relationship with the prescribed 95% isodose volume (PDV) and progression-free survival (PFS). Methods and Materials: Twenty-one patients with GB underwent chemoradiation therapy post-resection and biopsy. Radiation therapy (RT) treatment planning was based upon conventional MRI. Pre-RT DWIs were acquired in 3 orthogonal directions with b-values of 0, 1000, and 3000 s/mm{sup 2}. Hypercellularity volume (HCV) was defined on the high b-value (3000 s/mm{sup 2}) DWI by a threshold method. Nonenhanced signified regions not covered by the Gd-enhanced gross tumor volume (GTV-Gd) on T1-weighted images. The PDV was used to evaluate spatial coverage of the HCV by the dose plan. Association between HCV and PFS or other clinical covariates were assessed using univariate proportional hazards regression models. Results: HCVs and nonenhanced HCVs varied from 0.58 to 67 cm{sup 3} (median: 9.8 cm{sup 3}) and 0.15 to 60 cm{sup 3} (median: 2.5 cm{sup 3}), respectively. Fourteen patients had incomplete dose coverage of the HCV, 6 of whom had >1 cm{sup 3} HCV missed by the 95% PDV (range: 1.01-25.4 cm{sup 3}). Of the 15 patients who progressed, 5 progressed earlier, within 6 months post-RT, and 10 patients afterward. Pre-RT HCVs within recurrent GTVs-Gd were 78% (range: 65%-89%) for the 5 earliest progressions but lower, 53% (range: 0%-85%), for the later progressions. HCV and nonenhanced HCV were significant negative prognostic indicators for PFS (P<.002 and P<.01, respectively). The hypercellularity subvolume not covered by the 95% PDV was a significant negative predictor for PFS (P<.05). Conclusions: High b-value DWI

  4. Diffusion Weighted MR Imaging to Evaluate Treatment Results after Volumetric MR-guided High Intensity Focused Ultrasound of Uterine Fibroids: Influence of Different B-values

    NASA Astrophysics Data System (ADS)

    Voogt, M. J.; Keserci, B.; Kim, Y. S.; Rhim, H.; Lim, H. K.; Mougenot, C.; Kohler, M. O.; van den Bosch, M. A.; Vincken, K. L.; Bartels, L. W.

    2011-09-01

    We have assessed the feasibility of using diffusion weighted MR imaging (DWI) and apparent diffusion coefficient (ADC) mapping using different b-value combinations to evaluate treatment results after volumetric magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) for uterine fibroids. Pre-treatment, directly post-treatment and 1 month follow-up DW images were obtained using b-values 0, 200, 400, 600 and 800 s/mm2. ADC maps were constructed for quantitative analysis of ablation results. Four different combinations of b-values were used to calculate the ADC. Directly after treatment ADC values decreased. Low b-values (0 and 200 s/mm2) resulted in the best contrast between non-perfused and perfused tissue. One month after treatment the average ADC was increased, now showing the best contrast on the high b-value ADC maps.

  5. Detection of chronic brain damage by diffusion-weighted imaging with multiple b values in patients with type 2 diabetes.

    PubMed

    Liu, Tieli; Han, Yunpeng; Tang, Lemei; Wu, Jianlin; Miao, Yanwei; Gao, Bingbing; Shang, Jin

    2016-08-01

    The aim of the study was to evaluate the performance of parameters obtained from diffusion-weighted imaging (DWI) with multiple b values in the detection of chronic brain damage in patients with type 2 diabetes.We enrolled 30 patients with or without abnormalities on brain magnetic resonance imaging (lacunar infarction, leukoaraiosis, and/or brain atrophy) and 15 nondiabetic controls; obtained DWI parameters that included apparent diffusion coefficient (ADC), fast ADC (ADCfast), slow ADC (ADCslow), fraction of fast ADC (f), distributed diffusion coefficient (DDC), and stretched exponential (α); and performed receiver operating characteristic (ROC) analysis to evaluate the performance of parameters for the detection of chronic brain damage.The parameters ADC, ADCslow, f, and DDC were increased, whereas parameters ADCfast and α were decreased in type 2 diabetes patients compared with controls without diabetes. The centrum semiovale showed the most significant change in the evaluated parameters, and the changes in parameters ADCslow, f, and DDC were greater than the changes in other parameters. There was no significance between parameters of the biexponential model (ADCfast, ADCslow, f) and parameters of the stretched model (DDC, α), but parameters of both these models were superior to the parameter of monoexponential model (ADC). Moreover, ROC analysis showed that ADCslow of the centrum semiovale supplied by the anterior cerebral artery had the highest performance for detection of chronic brain damage (area under the ROC curve of 0.987, 93.3% sensitivity, and 100% specificity).Our study shows that DWI with multiple b values can quantitatively access chronic brain damage and may be used for detection and monitoring in type 2 diabetes patients. PMID:27583912

  6. Detection of chronic brain damage by diffusion-weighted imaging with multiple b values in patients with type 2 diabetes

    PubMed Central

    Liu, Tieli; Han, Yunpeng; Tang, Lemei; Wu, Jianlin; Miao, Yanwei; Gao, Bingbing; Shang, Jin

    2016-01-01

    Abstract The aim of the study was to evaluate the performance of parameters obtained from diffusion-weighted imaging (DWI) with multiple b values in the detection of chronic brain damage in patients with type 2 diabetes. We enrolled 30 patients with or without abnormalities on brain magnetic resonance imaging (lacunar infarction, leukoaraiosis, and/or brain atrophy) and 15 nondiabetic controls; obtained DWI parameters that included apparent diffusion coefficient (ADC), fast ADC (ADCfast), slow ADC (ADCslow), fraction of fast ADC (f), distributed diffusion coefficient (DDC), and stretched exponential (α); and performed receiver operating characteristic (ROC) analysis to evaluate the performance of parameters for the detection of chronic brain damage. The parameters ADC, ADCslow, f, and DDC were increased, whereas parameters ADCfast and α were decreased in type 2 diabetes patients compared with controls without diabetes. The centrum semiovale showed the most significant change in the evaluated parameters, and the changes in parameters ADCslow, f, and DDC were greater than the changes in other parameters. There was no significance between parameters of the biexponential model (ADCfast, ADCslow, f) and parameters of the stretched model (DDC, α), but parameters of both these models were superior to the parameter of monoexponential model (ADC). Moreover, ROC analysis showed that ADCslow of the centrum semiovale supplied by the anterior cerebral artery had the highest performance for detection of chronic brain damage (area under the ROC curve of 0.987, 93.3% sensitivity, and 100% specificity). Our study shows that DWI with multiple b values can quantitatively access chronic brain damage and may be used for detection and monitoring in type 2 diabetes patients. PMID:27583912

  7. Optimal b value of diffusion-weighted imaging on a 3.0T magnetic resonance scanner in Crohn’s disease

    PubMed Central

    Feng, Qi; Yan, Yun-Qi; Zhu, Jiong; Tong, Jin-Lu; Xu, Jian-Rong

    2014-01-01

    AIM: To determine the optimal b value of diffusion-weighted imaging for detecting active inflammation in Crohn’s disease. METHODS: Thirty-one patients clinically diagnosed with active Crohn’s disease were referred for magnetic resonance examination. All patients were scanned on a 3.0T magnetic resonance scanner using the same protocol involving four different b values (800, 1500, 2000 and 2500 s/mm2). The diagnostic effect of diffusion-weighted imaging was evaluated and compared with endoscopic findings. The diffusion-weighted image quality of four b value groups was evaluated and apparent diffusion coefficient was measured for both normal and inflammatory intestinal segments. RESULTS: The contrast-to-noise ratio and signal-to-noise ratio were not satisfied when b value 2000 or 2500 s/mm2 was adopted (36.52 ± 14.95 vs 34.78 ± 24.83, P > 0.05; 53.58 ± 23.45 vs 47.58 ± 29.67, P > 0.05). The qualitative image quality was not enough to meet diagnostic requirement. No matter which b value was chosen, the apparent diffusion coefficient of inflammatory intestinal segments was significantly lower than that of normal intestinal segments (1.38 ± 0.28 vs 2.00 ± 0.38, P < 0.01; 1.09 ± 0.20 vs 1.50 ± 0.28, P < 0.01; 0.95 ± 0.19 vs 1.34 ± 0.28, P < 0.01; 0.88 ± 0.14 vs 1.20 ± 0.21, P < 0.01). The lesion detection rate (90.32%), diagnostic sensitivity (81.18%) and specificity (95.10%) would be appropriate when b value 1500 s/mm2 was adopted. CONCLUSION: High b value is suitable for intestinal DW examination on a high field MR scanner. PMID:25253967

  8. Diffusion-Weighted Imaging with Two Different b-Values in Detection of Solid Focal Liver Lesions

    PubMed Central

    Yang, Da-wei; Wang, Ke-yang; Yao, Xun; Ye, Hui-yi; Jiang, Tao; Liu, Yuan; Gao, Jia-yin; Chen, Min; Zhou, Cheng; Yang, Zheng-han

    2016-01-01

    One hundred and eighty-two consecutive patients with suspected liver disease were recruited to receive diffusion-weighted imaging (DWI) with two different b-values, in comparison with T2-weighted imaging (T2WI). The detection rate of three MR sequences in solid focal liver lesions (FLLs) and subgroup analyses were performed. Our prospective study found that DWI600 was equivalent to DWI100 and T2WI for the detection of solid FLLs overall but was significantly more accurate in the detection of malignant solid FLLs and lesions larger than 10 mm. PMID:27019851

  9. Coronal Diffusion-weighted Magnetic Resonance Imaging of the Kidney: Agreement with Axial Diffusion-weighted Magnetic Imaging in Terms of Apparent Diffusion Coefficient Values

    PubMed Central

    Wang, Hai-Yi; Wang, Jia; Tang, Ye-Huan; Ye, Hui-Yi; Ma, Lin

    2015-01-01

    Background: Coronal diffusion-weighted magnetic resonance imaging (DW-MRI) and apparent diffusion coefficient (ADC) values have gradually become applied (following conventional axial DW-MRI) in the renal analysis. To explore whether data obtained using coronal DW-MRI are comparable with those derived using axial DW-MRI, this preliminary study sought to assess the agreement in renal ADC values between coronal DW-MRI and axial DW-MRI. Methods: Thirty-four healthy volunteers were enrolled in the study; written consents were obtained. All subjects underwent respiratory-triggered axial and coronal DW-MRI using a 1.5-MR system with b values of 0 and 800 s/mm2. The signal-to-noise ratios (SNRs) of the two DW-MRI sequences were measured and statistically compared using the paired t-test. The extent of agreement of ADC values of the upper pole, mid-pole, and lower pole of the kidney; the mean ADC values of the left kidney and right kidney; and the mean ADC values of the bilateral kidneys were evaluated via calculation of intraclass correlation coefficients (ICCs) or Bland–Altman method between the two DW-MRI sequences. Results: The SNR of coronal DW-MR images was statistically inferior to that of axial DW-MR images (P < 0.001). The ICCs of the ADC values of each region of interest, and the mean ADC values of bilateral kidneys, between the two sequences, were greater than 0.5, and the mean ADCs of the bilateral kidneys demonstrated the highest ICC (0.869; 95% confidence interval: 0.739–0.935). In addition, 94.1% (32/34), 94.1% (32/34), and 97.1% (31/34) of the ADC bias was inside the limits of agreement in terms of the mean ADC values of the left kidneys, right kidneys, and bilateral kidneys when coronal and axial DWI-MRI were compared. Conclusions: ADC values derived using coronal DW-MRI exhibited moderate-to-good agreement to those of axial DW-MRI, rendering the former an additional useful DW-MRI method, and causing the ADC values derived using the two types of DW

  10. Investigation of the optimal b-value to detect breast tumors with diffusion weighted imaging by 1.5-T MRI

    PubMed Central

    2014-01-01

    Background Previous studies have reported that the signal attenuation of diffusion-weighted magnetic resonance imaging (DWI) for normal breast tissue and tumor were well fitted by a monoexponential and a biexponential function, respectively. The aim of this study was to investigate the optimal b-value to detect breast tumors from DWI signal attenuations. Methods Sixty-four subjects with breast cancer underwent DWI using six b-values up to 3500 s/mm2. The signal attenuations of normal breast and tumor were fitted by mono- and biexponential functions, respectively. The maximum contrast b-values were estimated and compared in terms of frequency. Results In almost all cases, the contrast increased with a b-value from 0 to approximately 1500 s/mm2. For b > 1500 s/mm2, the contrast decreased. The highest contrast b-value in the range of 0 to 2500 s/mm2 most frequently was b = 1500 and the next most frequent was 1400 s/mm2. Comparing sensitivity and specificity between b = 700 and b = 1400 s/mm2, b =1400 s/mm2 was slightly superior. Conclusion Based on these results, DWI with a b-value of approximately 1400-1500 s/mm2 is recommended for optimizing breast tumor detectability. PMID:25608450

  11. Predicting Prostate Biopsy Outcomes: A Preliminary Investigation on Screening with Ultrahigh B-Value Diffusion-Weighted Imaging as an Innovative Diagnostic Biomarker

    PubMed Central

    Zhang, Kun; Shen, Yanguang; Zhang, Xu; Ma, Lu; Wang, Haiyi; An, Ningyu; Guo, Aitao; Ye, Huiyi

    2016-01-01

    Background Routine screening of prostate specific antigen (PSA) is no longer recommended because of a high rate of over-diagnosis of prostate cancer (PCa). Objective To evaluate the efficacy of diffusion-weighted magnetic resonance imaging (DW-MRI) for PCa detection, and to explore the clinical utility of ultrahigh b-value DW-MRI in predicting prostate biopsy outcomes. Methodology 73 male patients were selected for the study. They underwent 3T MRI using T2WI conventional DW-MRI with b-value 1000 s/mm2, and ultrahigh b-value DW-MRI with b-values of 2000 s/mm2 and 3000 s/mm2. Two radiologists evaluated individual prostate gland images on a 5-point rating scale using PI-RADS, for the purpose of region-specific comparisons among modalities. Sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV) and likelihood ratios (LR) were investigated for each MRI modality. The area under the receiver operating characteristic (ROC) curve (AUC) was also calculated. Results Results showed the improved diagnostic value of ultrahigh b-value DWI-MRI for detection of PCa when compared to other b values and conventional MRI protocols. Sensitivity values for 3000 s/mm2 in both peripheral zone (PZ) and transition zone (TZ) were significantly higher than those observed with conventional DW-MRI—Specificity values for 3000 s/mm2 in the TZ were significantly higher than other b-value images, whereas specificity values using 3000 s/mm2 in the PZ were not significantly higher than 2000 s/mm2 images. PPV and NPV between 3000 s/mm2 and the other three modalities were significantly higher for both PZ and TZ images. The PLRs and NLRs of b-value 3000 s/mm2 DW-MRI in the PZ and TZ were also recorded. ROC analysis showed greater AUCs for the b value 3000 s/mm2 DWI than for the other three modalities. Conclusions DW-MRI with a b-value of 3000 s/mm2 was found to be the most accurate and reliable MRI modality for PCa tumor detection and localization

  12. Diffusion-weighted imaging with apparent diffusion coefficient mapping and spectroscopy in prostate cancer.

    PubMed

    Jacobs, Michael A; Ouwerkerk, Ronald; Petrowski, Kyle; Macura, Katarzyna J

    2008-12-01

    Prostate cancer is a major health problem, and the exploration of noninvasive imaging methods that have the potential to improve specificity while maintaining high sensitivity is still critically needed. Tissue changes induced by tumor growth can be visualized by magnetic resonance imaging (MRI) methods. Current MRI methods include conventional T2-weighted imaging, diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping and magnetic resonance spectroscopy (MRS). Techniques such as DWI/ADC provide functional information about the behavior of water molecules in tissue; MRS can provide biochemical information about the presence or absence of certain metabolites, such as choline, creatine, and citrate. Finally, vascular parameters can be investigated using dynamic contrast-enhanced MRI. Moreover, with whole-body MRI and DWI, metastatic disease can be evaluated in 1 session and may provide a way to monitor treatment. Therefore, when combining these various methods, a multiparametric data set can be built to assist in the detection, localization, assessment of prostate cancer aggressiveness, and tumor staging. Such a comprehensive approach offers more power to evaluate prostate disease than any single measure alone. In this article, we focus on the role of DWI/ADC and MRS in the detection and characterization using both in vivo and ex vivo imaging of prostate pathology. PMID:19512848

  13. Fusion of high b-value diffusion-weighted and T2-weighted MR images improves identification of lymph nodes in the pelvis.

    PubMed

    Mir, N; Sohaib, S A; Collins, D; Koh, D M

    2010-08-01

    Accurate identification of lymph nodes facilitates nodal assessment by size, morphological or MR lymphographic criteria. We compared the MR detection of lymph nodes in patients with pelvic cancers using T2-weighted imaging, and fusion of diffusion-weighted imaging (DWI) and T2-weighted imaging. Twenty patients with pelvic tumours underwent 5-mm axial T2-weighted and DWI (b-values 0-750 s/mm(2)) on a 1.5T system. Fusion images of b = 750 s/mm(2) diffusion-weighted MR and T2-weighted images were created. Two radiologists evaluated in consensus the T2-weighted images and fusion images independently. For each image set, the location and diameter of pelvic nodes were recorded, and nodal visibility was scored using a 4-point scale (0-3). Nodal visualisation was compared using Relative to an Identified Distribution (RIDIT) analysis. The mean RIDIT score describes the probability that a randomly selected node will be better visualised relative to the other image set. One hundred fourteen pelvic nodes (mean 5.9 mm; 2-10 mm) were identified on T2-weighted images and 161 nodes (mean 4.3 mm; 2-10 mm) on fusion images. Using fusion images, 47 additional nodes were detected compared with T2-weighted images alone (eight external iliac, 24 inguinal, 12 obturator, two peri-rectal, one presacral). Nodes detected only on fusion images were 2-9 mm (mean 3.7 mm). Nodal visualisation was better using fusion images compared with T2-weighted images (mean RIDIT score 0.689 vs 0.302). Fusion of diffusion-weighted MR with T2-weighted images improves identification of pelvic lymph nodes compared with T2-weighted images alone. The improved nodal identification may aid treatment planning and further nodal characterisation. PMID:20718916

  14. Magnetic resonance diffusion-weighted imaging: sensitivity and apparent diffusion constant in stroke.

    PubMed

    Jones, S C; Perez-Trepichio, A D; Xue, M; Furlan, A J; Awad, I A

    1994-01-01

    Magnetic resonance diffusion-weighted imaging (MR-DWI) is sensitive to the diffusibility of water and may offer characterization and anatomical localization of stroke leading to early tailored therapeutic intervention. We compared DWI, the apparent diffusion constant (ADC), and autoradiographic cerebral blood flow (CBF) in a model of focal cerebral ischemia in the rat. Sprague-Dawley rats were embolized with a single silicone cylinder injected into the internal carotid artery. Both common carotids were permanently ligated. The animals were anesthetized (isoflurane in O2), and paralyzed (gallamine). MR-DWI were obtained with a GE 4.7 T magnet (TE = 3 s, TR = 80 msec, b = 2393.10(-3) mm2/s, slice thickness 3 mm). DWI and CBF autoradiograms were compared visually. ADC was assessed in various regions, including ischemic cortex and a region homologous to ischemic cortex. Imaging times from stroke onset were 50 +/- 6 min (mean +/- SEM) for DWI, 185 +/- 17 min for a second DWI. CBF was determined at 258 +/- 15 min. The specificity was 100% at both 50 min and 185 min, indicating that there were no false positives; in 3 animals ischemia was not present. However, the sensitivity analysis indicated that early DWI yields some false negatives; at 50 min the sensitivity was 60%. We attribute our result of low early sensitivity to small infarcts in relation to the slice thickness. Later, at 185 min, sensitivity was 100%. The first ADCs were higher than the second ADC values in ischemic cortex. For infarcts larger than the slice thickness, early MR-DWI is highly sensitive for imaging evolving ischemia.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7976548

  15. Diffusion-weighted MRI with parallel imaging technique: apparent diffusion coefficient determination in normal kidneys and in nonmalignant renal diseases.

    PubMed

    Macarini, Luca; Stoppino, Luca Pio; Milillo, Paola; Ciuffreda, Pierpaolo; Fortunato, Francesca; Vinci, Roberta

    2010-01-01

    The purpose of the study was to assess the capability and the reliability of apparent diffusion coefficient (ADC) measurements in the evaluation of different benign renal abnormalities. Twenty-five healthy volunteers and 31 patients, divided into seven different groups (A-G) according to pathology, underwent diffusion-weighted magnetic resonance imaging (DW MRI) of the kidneys using 1.5-T system. DW images were obtained in the axial plane with a spin-echo echo planar imaging single-shot sequence with three b values (0, 300, and 600 s/mm²). Before acquisition of DW sequences, we performed in each patient a morphological study of the kidneys. ADC was 2.40±0.20×10⁻³ mm² s⁻¹ in volunteers. A significant difference was found between Groups A (cysts=3.39±0.51×10⁻³ mm² s⁻¹) and B (acute/chronic renal failure=1.38±0.40×10⁻³ mm² s⁻¹) and between Groups A and C (chronic pyelonephritis=1.53±0.21×10⁻³ mm² s⁻¹) (P<.05). An important difference was also observed among Group D (hydronephrosis=4.82±0.35×10⁻³ mm² s⁻¹) and Groups A, B, and C (P<.05), whereas no differences were found between Groups B and C (P>.05). A considerable correlation between glomerular filtration rate and ADC was found (P=.04). In conclusion, significant differences were detected among different patient groups, and this suggests that ADC measurements can be useful in differentiating normal renal parenchyma from most commonly encountered nonmalignant renal lesions. PMID:21092872

  16. Liver lobe-based magnetic resonance diffusion-weighted imaging using multiple b values in patients with hepatitis B-related liver cirrhosis: association with the liver disease severity according to the Child-Pugh class

    PubMed Central

    Tang, Hong-Jie; Zhou, Li; Zhang, Xiao-Ming; Liu, Jun; Chen, Tian-Wu; Zeng, Nan-Lin; Wang, Dan; Li, Jie; Huang, Yu-Cheng; Tang, Yu-Lian; Hu, Jiani

    2015-01-01

    OBJECTIVE: To determine the associations of liver lobe-based magnetic resonance diffusion-weighted imaging findings using multiple b values with the presence and Child-Pugh class of cirrhosis in patients with hepatitis B. METHODS: Seventy-four cirrhotic patients with hepatitis B and 25 healthy volunteers underwent diffusion-weighted imaging using b values of 0, 500, 800 and 1000 sec/mm2. The apparent diffusion coefficients of individual liver lobes for b(0,500), b(0,800) and b(0,1000) were derived from the signal intensity averaged across images obtained using b values of 0 and 500 sec/mm2, 0 and 800 sec/mm2, or 0 and 1000 sec/mm2, respectively, and were statistically analyzed to evaluate cirrhosis. RESULTS: The apparent diffusion coefficients for b(0,500), b(0,800) and b(0,1000) inversely correlated with the Child-Pugh class in the left lateral liver lobe, the left medial liver lobe, the right liver lobe and the caudate lobe (r=–0.35 to –0.60, all p<0.05), except for the apparent diffusion coefficient for b(0,1000) in the left medial liver lobe (r=–0.17, p>0.05). Among these parameters, the apparent diffusion coefficient for b(0,500) in the left lateral liver lobe best differentiated normal from cirrhotic liver, with an area under the receiver operating characteristic curve of 0.989. The apparent diffusion coefficient for b(0,800) in the right liver lobe best distinguished Child-Pugh class A from B–C and A–B from C, with areas under the receiver operating characteristic curve of 0.732 and 0.747, respectively. CONCLUSION: Liver lobe-based apparent diffusion coefficients for b(0,500) and b(0,800) appear to be associated with the presence and Child-Pugh class of liver cirrhosis. PMID:26222818

  17. Accuracies and Contrasts of Models of the Diffusion-Weighted-Dependent Attenuation of the MRI Signal at Intermediate b-values

    PubMed Central

    Nicolas, Renaud; Sibon, Igor; Hiba, Bassem

    2015-01-01

    The diffusion-weighted-dependent attenuation of the MRI signal E(b) is extremely sensitive to microstructural features. The aim of this study was to determine which mathematical model of the E(b) signal most accurately describes it in the brain. The models compared were the monoexponential model, the stretched exponential model, the truncated cumulant expansion (TCE) model, the biexponential model, and the triexponential model. Acquisition was performed with nine b-values up to 2500 s/mm2 in 12 healthy volunteers. The goodness-of-fit was studied with F-tests and with the Akaike information criterion. Tissue contrasts were differentiated with a multiple comparison corrected nonparametric analysis of variance. F-test showed that the TCE model was better than the biexponential model in gray and white matter. Corrected Akaike information criterion showed that the TCE model has the best accuracy and produced the most reliable contrasts in white matter among all models studied. In conclusion, the TCE model was found to be the best model to infer the microstructural properties of brain tissue. PMID:26106263

  18. Diffusion-weighted MRI derived apparent diffusion coefficient identifies prognostically distinct subgroups of pediatric diffuse intrinsic pontine glioma.

    PubMed

    Lober, Robert M; Cho, Yoon-Jae; Tang, Yujie; Barnes, Patrick D; Edwards, Michael S; Vogel, Hannes; Fisher, Paul G; Monje, Michelle; Yeom, Kristen W

    2014-03-01

    While pediatric diffuse intrinsic pontine gliomas (DIPG) remain fatal, recent data have shown subgroups with distinct molecular biology and clinical behavior. We hypothesized that diffusion-weighted MRI can be used as a prognostic marker to stratify DIPG subsets with distinct clinical behavior. Apparent diffusion coefficient (ADC) values derived from diffusion-weighted MRI were computed in 20 consecutive children with treatment-naïve DIPG tumors. The median ADC for the cohort was used to stratify the tumors into low and high ADC groups. Survival, gender, therapy, and potential steroid effects were compared between the ADC groups. Median age at diagnosis was 6.6 (range 2.3-13.2) years, with median follow-up seven (range 1-36) months. There were 14 boys and six girls. Seventeen patients received radiotherapy, five received chemotherapy, and six underwent cerebrospinal fluid diversion. The median ADC of 1,295 × 10(-6) mm(2)/s for the cohort partitioned tumors into low or high diffusion groups, which had distinct median survivals of 3 and 13 months, respectively (log-rank p < 0.001). Low ADC tumors were found only in boys, whereas high ADC tumors were found in both boys and girls. Available tissue specimens in three low ADC tumors demonstrated high-grade histology, whereas one high ADC tumor demonstrated low-grade histology with a histone H3.1 K27M mutation and high-grade metastatic lesion at autopsy. ADC derived from diffusion-weighted MRI may identify prognostically distinct subgroups of pediatric DIPG. PMID:24522717

  19. A study of the relationship between gender/age and apparent diffusion coefficient values in spleen of healthy adults using diffusion-weighted magnetic resonance imaging

    PubMed Central

    Nazarlou, Ali Kiani; Abdolmohammadi, Jamil

    2015-01-01

    Background: Diffusion-weighted magnetic resonance imaging (DWI) systems are very effective in detecting strokes, and they also have shown significant promise in the detection of fibrosis and cirrhosis of the liver. However, such systems have the disadvantages of poor reproducibility and noise, which can diminish the accuracy of the apparent diffusion coefficients (ADCs) provided by the DWI process. The main aim of this study was to determine the relationship between the age and gender of healthy adults in terms of the ADC values of the spleen measured by DWI. Methods: Sixty-nine subjects selected for this study from people who were referred to the Tabesh Medical Imaging Center in Tabriz, Iran, in 2013. Each subject underwent echo-planar DWI for her or his ADC values of the spleen with b-values of 50, 400, and 800 s/mm2, and the resulting ADC values were evaluated. Results: No significant differences were observed in ADC values of the spleen among the female and male participants or those from various ages (P>0.05). Conclusions: Based on the findings of this study, it was concluded that the effect of age and gender on the spleen’s ADC values can be omitted from the spleen-diagnosis procedure. In other words, the spleen’s ADC values are not related to the age or the gender of healthy adults. PMID:26052412

  20. Diffusion-weighted magnetic resonance imaging in cancer: Reported apparent diffusion coefficients, in-vitro and in-vivo reproducibility

    PubMed Central

    Jafar, Maysam M; Parsai, Arman; Miquel, Marc E

    2016-01-01

    There is considerable disparity in the published apparent diffusion coefficient (ADC) values across different anatomies. Institutions are increasingly assessing repeatability and reproducibility of the derived ADC to determine its variation, which could potentially be used as an indicator in determining tumour aggressiveness or assessing tumour response. In this manuscript, a review of selected articles published to date in healthy extra-cranial body diffusion-weighted magnetic resonance imaging is presented, detailing reported ADC values and discussing their variation across different studies. In total 115 studies were selected including 28 for liver parenchyma, 15 for kidney (renal parenchyma), 14 for spleen, 13 for pancreatic body, 6 for gallbladder, 13 for prostate, 13 for uterus (endometrium, myometrium, cervix) and 13 for fibroglandular breast tissue. Median ADC values in selected studies were found to be 1.28 × 10-3 mm2/s in liver, 1.94 × 10-3 mm2/s in kidney, 1.60 × 10-3 mm2/s in pancreatic body, 0.85 × 10-3 mm2/s in spleen, 2.73 × 10-3 mm2/s in gallbladder, 1.64 × 10-3 mm2/s and 1.31 × 10-3 mm2/s in prostate peripheral zone and central gland respectively (combined median value of 1.54×10-3 mm2/s), 1.44 × 10-3 mm2/s in endometrium, 1.53 × 10-3 mm2/s in myometrium, 1.71 × 10-3 mm2/s in cervix and 1.92 × 10-3 mm2/s in breast. In addition, six phantom studies and thirteen in vivo studies were summarized to compare repeatability and reproducibility of the measured ADC. All selected phantom studies demonstrated lower intra-scanner and inter-scanner variation compared to in vivo studies. Based on the findings of this manuscript, it is recommended that protocols need to be optimised for the body part studied and that system-induced variability must be established using a standardized phantom in any clinical study. Reproducibility of the measured ADC must also be assessed in a volunteer population, as variations are far more significant in vivo compared

  1. Predicting liver metastasis of gastrointestinal tract cancer by diffusion-weighted imaging of apparent diffusion coefficient values

    PubMed Central

    Zheng, De-Xian; Meng, Shu-Chun; Liu, Qing-Jun; Li, Chuan-Ting; Shang, Xi-Dan; Zhu, Yu-Seng; Bai, Tian-Jun; Xu, Shi-Ming

    2016-01-01

    AIM: To determine if efficacy of chemotherapy on liver metastasis of gastrointestinal tract cancer can be predicted by apparent diffusion coefficient (ADC) values of diffusion-weighted imaging (DWI). METHODS: In total, 86 patients with liver metastasis of gastrointestinal tract cancer (156 metastatic lesions) diagnosed in our hospital were included in this study. The maximum diameters of these tumors were compared with each other before treatment, 2 wk after treatment, and 12 wk after treatment. Selected patients were classified as the effective group and the ineffective group, depending on the maximum diameter of the tumor after 12 wk of treatment; and the ADC values at different treatment times between the two groups were compared. Spearman rank correlation was used to analyze the relationship between ADC value and tumor diameter. Receiver operating characteristic curve (ROC curve) was used to analyze the ADC values before treatment to predict the patient’s sensitivity and specificity degree of efficacy to the chemotherapy. RESULTS: There was no difference in age between the two groups and in maximum tumor diameter before treatment and 2 wk after treatment. However, after 12 wk of treatment, maximum tumor diameter in the effective group was significantly lower than that in the ineffective group (P < 0.05). Before treatment, ADC values in the ineffective group were significantly higher than those in the effective group (P < 0.05). There was no difference in ADC values between the effective and ineffective groups after 2 and 12 wk of treatment. However, ADC values were significantly higher after 2 and 12 wk of treatment compared to before treatment in the effective group (P < 0.05). Spearman rank correlation analysis showed that ADC value before treatment and the reduced percentage of the maximum tumor diameter after 12 wk of treatment were negatively correlated, while the increase in the percentage of the ADC value 12 wk after treatment and the decrease in the

  2. Early Changes in Apparent Diffusion Coefficient From Diffusion-Weighted MR Imaging During Radiotherapy for Prostate Cancer

    SciTech Connect

    Park, Sung Yoon; Kim, Chan Kyo; Park, Byung Kwan; Park, Won; Park, Hee Chul; Han, Deok Hyun; Kim, Bohyun

    2012-06-01

    Purpose: To investigate the feasibility of diffusion-weighted MRI (DWI) as an early and reproducible change indicator in patients receiving radiotherapy for prostate cancer (PC). Methods and Materials: Eight consecutive patients with biopsy-proven PC underwent DWI at 3T. All patients who received external-beam radiotherapy had four serial MR scans, as follows: before therapy (PreTx); after 1 week of therapy (PostT1); after 3 weeks of therapy (PostT2); and 1 month after the completion of therapy (PostT3). At each time, the apparent diffusion coefficient (ADC) was measured in tumors and normal tissues. For reproducibility of the ADC measurement, five patients also had two separate pretreatment DWI scans at an interval of <2 weeks. Serum prostate-specific antigen (PSA) levels were evaluated at the same time as MR scans. Results: Thirteen tumors (peripheral zone = 10; transition zone = 3) were found. The mean ADC values for the tumors from PreTx to PostT3 were 0.86, 1.03, 1.15, and 1.26 Multiplication-Sign 10{sup -3} mm{sup 2}/s in sequence, respectively. Compared with PreTx, PostT1 (p = 0.005), PostT2 (p = 0.003), and PostT3 (p < 0.001) showed a significant increase in ADC values. The mean ADC values of the benign tissues from PreTx to PostT3 were 1.60, 1.58, 1.47, and 1.46 Multiplication-Sign 10{sup -3} mm{sup 2}/s in sequence, respectively. Reproducibility of ADC measurements was confirmed with a mean difference in ADC of -0.04 in peripheral zone and -0.017 in transition zone between two separate pretreatment MR scans. The mean PSA levels from PreTx to PostT3 were 9.05, 9.18, 9.25, and 4.11 ng/mL in sequence, respectively. Conclusions: DWI, as a reproducible biomarker, has the potential to evaluate the early therapeutic changes of PC to radiotherapy.

  3. Estimation of optimal b-value sets for obtaining apparent diffusion coefficient free from perfusion in non-small cell lung cancer

    NASA Astrophysics Data System (ADS)

    Karki, Kishor; Hugo, Geoffrey D.; Ford, John C.; Olsen, Kathryn M.; Saraiya, Siddharth; Groves, Robert; Weiss, Elisabeth

    2015-10-01

    The purpose of this study was to determine optimal sets of b-values in diffusion-weighted MRI (DW-MRI) for obtaining monoexponential apparent diffusion coefficient (ADC) close to perfusion-insensitive intravoxel incoherent motion (IVIM) model ADC (ADCIVIM) in non-small cell lung cancer. Ten subjects had 40 DW-MRI scans before and during radiotherapy in a 1.5 T MRI scanner. Respiratory triggering was applied to the echo-planar DW-MRI with \\text{TR}≈ 4500 ms, TE  =  74 ms, eight b-values of 0-1000 μs μm-2, pixel size  =  1.98× 1.98 mm2, slice thickness  =  6 mm, interslice gap  =  1.2 mm, 7 axial slices and total acquisition time ≈6 min. One or more DW-MRI scans together covered the whole tumour volume. Monoexponential model ADC values using various b-value sets were compared to reference-standard ADCIVIM values using all eight b-values. Intra-scan coefficient of variation (CV) of active tumour volumes was computed to compare the relative noise in ADC maps. ADC values for one pre-treatment DW-MRI scan of each of the 10 subjects were computed using b-value pairs from DW-MRI images synthesized for b-values of 0-2000 μs μm-2 from the estimated IVIM parametric maps and corrupted by various Rician noise levels. The square root of mean of squared error percentage (RMSE) of the ADC value relative to the corresponding ADCIVIM for the tumour volume of the scan was computed. Monoexponential ADC values for the b-value sets of 250 and 1000; 250, 500 and 1000; 250, 650 and 1000; 250, 800 and 1000; and 250-1000 μs μm-2 were not significantly different from ADCIVIM values (p>0.05 , paired t-test). Mean error in ADC values for these sets relative to ADCIVIM were within 3.5%. Intra-scan CVs for these sets were comparable to that for ADCIVIM. The monoexponential ADC values for other sets—0-1000 50-1000 100-1000 500-1000 and 250 and 800 μs μm-2 were significantly different from the ADCIVIM values. From Rician noise simulation

  4. The efficacy of diffusion weighted imaging and apparent diffusion coefficients mapping for liver metastasis of colonic adenocarcinomas

    PubMed Central

    Metin, Melike R.; Aydın, Hasan; Çetin, Hüseyin; Özmen, Evrim; Kayaçetin, Serra

    2016-01-01

    Objectives: To establish retrospectively the relation between the histopathologic grade of colorectal liver metastasis and apparent diffusion coefficient (ADC) values of hepatic metastases of colorectal adenocarcinomas. Methods: The diagnoses of liver metastases were confirmed with biopsy, surgery, and follow-up imaging findings. Twenty-six patients with 94 liver metastasis were included in the study. Of 94 masses, 59 were poorly-differentiated adenocarcinoma, 18 were moderately-differentiated adenocarcinoma, and 17 were well-differentiated regarding the diameters, ADC values, and ratio index (RI) values. Kolmogorov-smirnov normality test, Kruskal-wallis analysis of variance, Mann-Whitney U test with Bonferroni correction, Spearman correlation analysis, and receiver operating characteristics curve methods were applied to evaluate the statistical relations. Results: There was a statistically significant difference in terms of ADC values and RI between poorly-differentiated adenocarcinoma and moderately-differentiated adenocarcinoma plus well-differentiated adenocarcinomas. Poorly-differentiated adenocarcinomas have the lowest ADC values and highest RI values among other groups. Conclusion: Use of ADC values alone can be executed for the diagnosis of focal hepatic masses and also can aid in the differentiation of benign and malignant hepatic lesions. PMID:27052280

  5. WE-G-18C-02: Estimation of Optimal B-Value Set for Obtaining Apparent Diffusion Coefficient Free From Perfusion in Non-Small Cell Lung Cancer

    SciTech Connect

    Karki, K; Hugo, G; Ford, J; Saraiya, S; Weiss, E; Olsen, K; Groves, R

    2014-06-15

    Purpose: Diffusion-weighted MRI (DW-MRI) is increasingly being investigated for radiotherapy planning and response assessment. Selection of a limited number of b-values in DW-MRI is important to keep geometrical variations low and imaging time short. We investigated various b-value sets to determine an optimal set for obtaining monoexponential apparent diffusion coefficient (ADC) close to perfusion-insensitive intravoxel incoherent motion (IVIM) model ADC (ADCIVIM) in nonsmall cell lung cancer. Methods: Seven patients had 27 DW-MRI scans before and during radiotherapy in a 1.5T scanner. Respiratory triggering was applied to the echo-planar DW-MRI with TR=4500ms approximately, TE=74ms, pixel size=1.98X1.98mm{sub 2}, slice thickness=4–6mm and 7 axial slices. Diffusion gradients were applied to all three axes producing traceweighted images with eight b-values of 0–1000μs/μm{sup 2}. Monoexponential model ADC values using various b-value sets were compared to ADCIVIM using all b-values. To compare the relative noise in ADC maps, intra-scan coefficient of variation (CV) of active tumor volumes was computed. Results: ADCIVIM, perfusion coefficient and perfusion fraction for tumor volumes were in the range of 880-1622 μm{sup 2}/s, 8119-33834 μm{sup 2}/s and 0.104–0.349, respectively. ADC values using sets of 250, 800 and 1000; 250, 650 and 1000; and 250–1000μs/μm{sup 2} only were not significantly different from ADCIVIM(p>0.05, paired t-test). Error in ADC values for 0–1000, 50–1000, 100–1000, 250–1000, 500–1000, and three b-value sets- 250, 500 and 1000; 250, 650 and 1000; and 250, 800 and 1000μs/μm{sup 2} were 15.0, 9.4, 5.6, 1.4, 11.7, 3.7, 2.0 and 0.2% relative to the reference-standard ADCIVIM, respectively. Mean intrascan CV was 20.2, 20.9, 21.9, 24.9, 32.6, 25.8, 25.4 and 24.8%, respectively, whereas that for ADCIVIM was 23.3%. Conclusion: ADC values of two 3 b-value sets

  6. Diffusion weighted MR and apparent diffusion coefficient measurement in classification and characterization of noncystic focal liver lesions: does a clinical role exist?

    PubMed

    Mungai, Francesco; Morone, Mario; Villanacci, Alberta; Bondioni, Maria Pia; Mazzoni, Lorenzo Nicola; Grazioli, Luigi; Colagrande, Stefano

    2014-07-01

    The objective of this study was to assess the clinical role of apparent diffusion coefficient (ADC) analysis in noncystic focal liver lesion (FLL) classification/characterization.Six hundred liver magnetic resonances with multi-b (b = 50, 400, 800 s/mm) diffusion-weighted imaging (DwI) were retrospectively reviewed. Mean ADC was measured in 388 lesions (195 benign and 193 malignant) excluding internal necrotic areas. Cystic benign lesions were excluded from analysis. Sensitivity and specificity in distinguishing benign from malignant lesions were calculated. Analysis of variance was performed to detect differences among subgroups of solid lesions.Mean ADC of malignant lesions was 0.980 × 10 mm/s, significantly (P < 0.05) lower than mean ADC of benign lesions (1.433 × 10 mm/s). Applying an ADC cutoff of 1.066 × 10 mm/s, specificity and sensitivity for malignancy were respectively 86.6% and 73.6%. Of all lesions, >1/3 (39.5%) presented values lower than 1 × 10 mm/s, with 90.0% chance of malignancy. Above 1.5 × 10 mm/s (about 20% of all lesions) chance of malignancy was 9.5%.DwI cannot assist in noncystic FLL characterization, but can help in FLL classification in about half the cases. PMID:25058143

  7. Time course of diffusion weighted image and apparent diffusion coefficient in acute spinal cord infarction: A case report and review of the literature.

    PubMed

    Takeshita, Sho; Ogata, Toshiyasu; Mera, Hidekazu; Tsugawa, Jun; Fukae, Jiro; Tsuboi, Yoshio

    2016-05-31

    An 80-year-old woman was admitted to our hospital with acute onset of flaccid paraplegia and sensory and urinary disturbances that developed soon after acute pain in her lower back and leg. Neurological examination revealed, severe flaccid paraplegia, bladder and rectal disturbances and dissociated sensory loss below the level of L1 spinal cord segment. MR imaging with T2 weighted imaging (T2WI) and diffusion weighted imaging (DWI) on day 2 showed hyper signal intensity in the spinal cord at the vertebral level of L1 while initial apparent diffusion coefficient (ADC) showed decreased signal intensity in the lesion. We diagnosed spinal cord infarction, and anticoagulant and neuroprotective agents were administrated. Serial MRI findings revealed that the DWI signal of the lesion attenuated with time, and pseudo-normalization of the ADC occurred approximately 1 month after onset. These findings were similar to those seen in brain infarction. Our patient demonstrated serial MRI changes of spinal cord infarction showing anterior spinal cord syndrome. PMID:27098903

  8. Diffusion Weighted Imaging for Differentiating Benign from Malignant Orbital Tumors: Diagnostic Performance of the Apparent Diffusion Coefficient Based on Region of Interest Selection Method

    PubMed Central

    Xu, Xiao-Quan; Hu, Hao; Su, Guo-Yi; Liu, Hu; Shi, Hai-Bin

    2016-01-01

    Objective To evaluate the differences in the apparent diffusion coefficient (ADC) measurements based on three different region of interest (ROI) selection methods, and compare their diagnostic performance in differentiating benign from malignant orbital tumors. Materials and Methods Diffusion-weighted imaging data of sixty-four patients with orbital tumors (33 benign and 31 malignant) were retrospectively analyzed. Two readers independently measured the ADC values using three different ROIs selection methods including whole-tumor (WT), single-slice (SS), and reader-defined small sample (RDSS). The differences of ADC values (ADC-ROIWT, ADC-ROISS, and ADC-ROIRDSS) between benign and malignant group were compared using unpaired t test. Receiver operating characteristic curve was used to determine and compare their diagnostic ability. The ADC measurement time was compared using ANOVA analysis and the measurement reproducibility was assessed using Bland-Altman method and intra-class correlation coefficient (ICC). Results Malignant group showed significantly lower ADC-ROIWT, ADC-ROISS, and ADC-ROIRDSS than benign group (all p < 0.05). The areas under the curve showed no significant difference when using ADC-ROIWT, ADC-ROISS, and ADC-ROIRDSS as differentiating index, respectively (all p > 0.05). The ROISS and ROIRDSS required comparable measurement time (p > 0.05), while significantly shorter than ROIWT (p < 0.05). The ROISS showed the best reproducibility (mean difference ± limits of agreement between two readers were 0.022 [-0.080–0.123] × 10-3 mm2/s; ICC, 0.997) among three ROI methods. Conclusion Apparent diffusion coefficient values based on the three different ROI selection methods can help to differentiate benign from malignant orbital tumors. The results of measurement time, reproducibility and diagnostic ability suggest that the ROISS method are potentially useful for clinical practice. PMID:27587953

  9. Diffusion Weighted MR and Apparent Diffusion Coefficient Measurement in Classification and Characterization of Noncystic Focal Liver Lesions: Does a Clinical Role Exist?

    PubMed Central

    Mungai, Francesco; Morone, Mario; Villanacci, Alberta; Bondioni, Maria Pia; Mazzoni, Lorenzo Nicola; Grazioli, Luigi; Colagrande, Stefano

    2014-01-01

    Abstract The objective of this study was to assess the clinical role of apparent diffusion coefficient (ADC) analysis in noncystic focal liver lesion (FLL) classification/characterization. Six hundred liver magnetic resonances with multi-b (b = 50, 400, 800 s/mm2) diffusion-weighted imaging (DwI) were retrospectively reviewed. Mean ADC was measured in 388 lesions (195 benign and 193 malignant) excluding internal necrotic areas. Cystic benign lesions were excluded from analysis. Sensitivity and specificity in distinguishing benign from malignant lesions were calculated. Analysis of variance was performed to detect differences among subgroups of solid lesions. Mean ADC of malignant lesions was 0.980 × 10−3 mm2/s, significantly (P < 0.05) lower than mean ADC of benign lesions (1.433 × 10−3 mm2/s). Applying an ADC cutoff of 1.066 × 10−3 mm2/s, specificity and sensitivity for malignancy were respectively 86.6% and 73.6%. Of all lesions, >1/3 (39.5%) presented values lower than 1 × 10−3 mm2/s, with 90.0% chance of malignancy. Above 1.5 × 10−3 mm2/s (about 20% of all lesions) chance of malignancy was 9.5%. DwI cannot assist in noncystic FLL characterization, but can help in FLL classification in about half the cases. PMID:25058143

  10. Assessment of treatment response by total tumor volume and global apparent diffusion coefficient using diffusion-weighted MRI in patients with metastatic bone disease: a feasibility study.

    PubMed

    Blackledge, Matthew D; Collins, David J; Tunariu, Nina; Orton, Matthew R; Padhani, Anwar R; Leach, Martin O; Koh, Dow-Mu

    2014-01-01

    We describe our semi-automatic segmentation of whole-body diffusion-weighted MRI (WBDWI) using a Markov random field (MRF) model to derive tumor total diffusion volume (tDV) and associated global apparent diffusion coefficient (gADC); and demonstrate the feasibility of using these indices for assessing tumor burden and response to treatment in patients with bone metastases. WBDWI was performed on eleven patients diagnosed with bone metastases from breast and prostate cancers before and after anti-cancer therapies. Semi-automatic segmentation incorporating a MRF model was performed in all patients below the C4 vertebra by an experienced radiologist with over eight years of clinical experience in body DWI. Changes in tDV and gADC distributions were compared with overall response determined by all imaging, tumor markers and clinical findings at serial follow up. The segmentation technique was possible in all patients although erroneous volumes of interest were generated in one patient because of poor fat suppression in the pelvis, requiring manual correction. Responding patients showed a larger increase in gADC (median change = +0.18, range = -0.07 to +0.78 × 10(-3) mm2/s) after treatment compared to non-responding patients (median change = -0.02, range = -0.10 to +0.05 × 10(-3) mm2/s, p = 0.05, Mann-Whitney test), whereas non-responding patients showed a significantly larger increase in tDV (median change = +26%, range = +3 to +284%) compared to responding patients (median change = -50%, range = -85 to +27%, p = 0.02, Mann-Whitney test). Semi-automatic segmentation of WBDWI is feasible for metastatic bone disease in this pilot cohort of 11 patients, and could be used to quantify tumor total diffusion volume and median global ADC for assessing response to treatment. PMID:24710083

  11. Apparent diffusion coefficient of breast cancer and normal fibroglandular tissue in diffusion-weighted imaging: the effects of menstrual cycle and menopausal status.

    PubMed

    Kim, Jin You; Suh, Hie Bum; Kang, Hyun Jung; Shin, Jong Ki; Choo, Ki Seok; Nam, Kyung Jin; Lee, Seok Won; Jung, Young Lae; Bae, Young Tae

    2016-05-01

    The purpose of this study was to investigate prospectively whether the apparent diffusion coefficients (ADCs) of both breast cancer and normal fibroglandular tissue vary with the menstrual cycle and menopausal status. Institutional review board approval was obtained, and informed consent was obtained from each participant. Fifty-seven women (29 premenopausal, 28 postmenopausal) with newly diagnosed breast cancer underwent diffusion-weighted imaging twice (interval 12-20 days) before surgery. Two radiologists independently measured ADC of breast cancer and normal contralateral breast tissue, and we quantified the differences according to the phases of menstrual cycle and menopausal status. With normal fibroglandular tissue, ADC was significantly lower in postmenopausal than in premenopausal women (P = 0.035). In premenopausal women, ADC did not differ significantly between proliferative and secretory phases in either breast cancer or normal fibroglandular tissue (P = 0.969 and P = 0.519, respectively). In postmenopausal women, no significant differences were found between ADCs measured at different time intervals in either breast cancer or normal fibroglandular tissue (P = 0.948 and P = 0.961, respectively). The within-subject variability of the ADC measurements was quantified using the coefficient of variation (CV) and was small: the mean CVs of tumor ADC were 2.90 % (premenopausal) and 3.43 % (postmenopausal), and those of fibroglandular tissue ADC were 4.37 % (premenopausal) and 2.55 % (postmenopausal). Both intra- and interobserver agreements were excellent for ADC measurements, with intraclass correlation coefficients in the range of 0.834-0.974. In conclusion, the measured ADCs of breast cancer and normal fibroglandular tissue were not affected significantly by menstrual cycle, and the measurements were highly reproducible both within and between observers. PMID:27091644

  12. Tubo-Ovarian Abscess (with/without Pseudotumor Area) Mimicking Ovarian Malignancy: Role of Diffusion-Weighted MR Imaging with Apparent Diffusion Coefficient Values

    PubMed Central

    Wang, Tingting; Li, Wenhua; Wu, Xiangru; Yin, Bing; Chu, Caiting; Ding, Ming; Cui, Yanfen

    2016-01-01

    Objective To assess the added value of diffusion-weighted magnetic resonance imaging (DWI) with apparent diffusion coefficient (ADC) values compared to MRI, for characterizing the tubo-ovarian abscesses (TOA) mimicking ovarian malignancy. Materials and Methods Patients with TOA (or ovarian abscess alone; n = 34) or ovarian malignancy (n = 35) who underwent DWI and MRI were retrospectively reviewed. The signal intensity of cystic and solid component of TOAs and ovarian malignant tumors on DWI and the corresponding ADC values were evaluated, as well as clinical characteristics, morphological features, MRI findings were comparatively analyzed. Receiver operating characteristic (ROC) curve analysis based on logistic regression was applied to identify different imaging characteristics between the two patient groups and assess the predictive value of combination diagnosis with area under the curve (AUC) analysis. Results The mean ADC value of the cystic component in TOA was significantly lower than in malignant tumors (1.04 ± 0 .41 × 10−3 mm2/s vs. 2.42 ± 0.38 × 10−3 mm2/s; p < 0.001). The mean ADC value of the enhanced solid component in 26 TOAs was 1.43 ± 0.16×10−3mm2/s, and 46.2% (12 TOAs; pseudotumor areas) showed significantly higher signal intensity on DW-MRI than in ovarian malignancy (mean ADC value 1.44 ± 0.20×10−3 mm2/s vs.1.18 ± 0.36 × 10−3 mm2/s; p = 0.043). The combination diagnosis of ADC value and dilated tubal structure achieved the best AUC of 0.996. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of MRI vs. DWI with ADC values for predicting TOA were 47.1%, 91.4%, 84.2%, 64%, and 69.6% vs. 100%, 97.1%, 97.1%, 100%, and 98.6%, respectively. Conclusions DW-MRI is superior to MRI in the assessment of TOA mimicking ovarian malignancy, and the ADC values aid in discriminating the pseudotumor area of TOA from the solid portion of ovarian malignancy. PMID:26894926

  13. Diffusion-weighted imaging in pediatric body magnetic resonance imaging.

    PubMed

    Chavhan, Govind B; Caro-Dominguez, Pablo

    2016-05-01

    Diffusion-weighted MRI is being increasingly used in pediatric body imaging. Its role is still emerging. It is used for detection of tumors and abscesses, differentiation of benign and malignant tumors, and detection of inflamed bowel segments in inflammatory bowel disease in children. It holds great promise in the assessment of therapy response in body tumors, with apparent diffusion coefficient (ADC) value as a potential biomarker. Significant overlap of ADC values of benign and malignant processes and less reproducibility of ADC measurements are hampering its widespread use in clinical practice. With standardization of the technique, diffusion-weighted imaging (DWI) is likely to be used more frequently in clinical practice. We discuss the principles and technique of DWI, selection of b value, qualitative and quantitative assessment, and current status of DWI in evaluation of disease processes in the pediatric body. PMID:27229502

  14. DIFFUSION-WEIGHTED IMAGING OF THE LIVER: TECHNIQUES AND APPLICATIONS

    PubMed Central

    Lewis, Sara; Dyvorne, Hadrien; Cui, Yong; Taouli, Bachir

    2014-01-01

    SYNOPSIS Diffusion weighted MRI (DWI) is a technique that assesses the cellularity, tortuosity of the extracellular/extravascular space and cell membrane density based upon differences in water proton mobility in tissues. The strength of the diffusion weighting is reflected by the b-value. DWI using several b-values enables quantification of the apparent diffusion coefficient (ADC). DWI is increasingly employed in liver imaging for multiple reasons: it can add useful qualitative and quantitative information to conventional imaging sequences, it is acquired relatively quickly, it is easily incorporated into existing clinical protocols, and it is a non-contrast technique. DWI is useful for focal liver lesion detection and characterization, for the assessment of post-treatment tumor response and for evaluation of diffuse liver disease. ADC quantification can be used to characterize lesions as cystic/necrotic or solid and for predicting tumor response to therapy. Advanced diffusion methods such as IVIM (intravoxel incoherent motion) may have potential for detection, staging and evaluation of the progression of liver fibrosis and for liver lesion characterization. The lack of standardization of DWI technique including choice of b-values and sequence parameters has somewhat limited its widespread adoption. PMID:25086935

  15. Liver diffusion-weighted MR imaging: the tower of Babel?

    PubMed

    Guiu, Boris; Cercueil, Jean-Pierre

    2011-03-01

    There is a growing amount of literature regarding diffusion-weighted imaging (DWI) of the liver. The apparent diffusion coefficient (ADC) was introduced in 1986 and is used extensively in studies. However, methods for calculating ADC vary considerably and the value of the ADC strongly depends on the b values chosen for its calculation. Indeed, the ADC incorporates the effects of both diffusion and perfusion, which can vary independently. Since signal attenuation as a function of b follows a bi-exponential pattern, other diffusion/perfusion coefficients can be calculated using DWI, and these may provide more meaningful measurements than the ADC. The absence of standardization for both the terminology and the methodology in DWI of the liver makes it difficult for readers to understand the technique used and strongly limits comparisons between studies. Here, we review the main principles of DWI of the liver, the limits of the ADC, and the exciting capabilities of multi-parametric DWI. We also insisted on the need for a common language for DWI of the liver. PMID:21110195

  16. The utility of diffusion-weighted magnetic resonance imaging in differentiation of endometriomas from hemorrhagic ovarian cysts.

    PubMed

    Balaban, Mehtap; Idilman, Ilkay S; Toprak, Huseyin; Unal, Ozlem; Ipek, Ali; Kocakoc, Ercan

    2015-01-01

    The aim was to determine the utility of diffusion-weighted magnetic resonance imaging (DW MRI) and apparent diffusion coefficient (ADC) measurements in differentiation of endometrioma and hemorrhagic ovarian cyst. A total of 24 female patients who underwent pelvic MRI with an initial diagnosis of ovarian cyst were included in the study. The final diagnosis was endometrioma in 12 patients and hemorrhagic ovarian cyst in 12 patients. We observed significantly lower ADC values in endometriomas compared with hemorrhagic ovarian cysts in all b values. DW MRI with quantitative ADC measurements can be used for differentiation of endometrioma from hemorrhagic ovarian cysts. PMID:25986161

  17. Technique of diffusion weighted imaging and its application in stroke

    NASA Astrophysics Data System (ADS)

    Li, Enzhong; Tian, Jie; Han, Ying; Wang, Huifang; Li, Wu; He, Huiguang

    2003-05-01

    To study the application of diffusion weighted imaging and image post processing in the diagnosis of stroke, especially in acute stroke, 205 patients were examined by 1.5 T or 1.0 T MRI scanner and the images such as T1, T2 and diffusion weighted images were obtained. Image post processing was done with "3D Med System" developed by our lab to analyze data and acquire the apparent diffusion coefficient (ADC) map. In acute and subacute stage of stroke, the signal in cerebral infarction areas changed to hyperintensity in T2- and diffusion-weighted images, normal or hypointensity in T1-weighted images. In hyperacute stage, however, the signal was hyperintense just in the diffusion weighted imaes; others were normal. In the chronic stage, the signal in T1- and diffusion-weighted imaging showed hypointensity and hyperintensity in T2 weighted imaging. Because ADC declined obviously in acute and subacute stage of stroke, the lesion area was hypointensity in ADC map. With the development of the disease, ADC gradually recovered and then changed to hyperintensity in ADC map in chronic stage. Using diffusion weighted imaging and ADC mapping can make a diagnosis of stroke, especially in the hyperacute stage of stroke, and can differentiate acute and chronic stroke.

  18. Assessment of Activity of Crohn Disease by Diffusion-Weighted Magnetic Resonance Imaging.

    PubMed

    Li, Xue-Hua; Sun, Can-Hui; Mao, Ren; Zhang, Zhong-Wei; Jiang, Xiao-Song; Pui, Margaret H; Chen, Min-Hu; Li, Zi-Ping

    2015-10-01

    To assess the diagnostic efficacy of diffusion-weighted MR imaging (DWI) for evaluating inflammatory activity in patients with Crohn's disease (CD). A total of 47 CD patients underwent MR enterography (MRE) and DWI using 3 b values of 50, 400, and 800 s/mm. Apparent diffusion coefficients (ADCs) of inflamed and normal bowel wall were calculated. The conventional MRE findings and DWI signal intensities were qualitatively scored from 0 to 3. The correlation between Crohn disease activity index (CDAI) and both ADCs and magnetic resonance imaging scores was analyzed. Receiver-operating characteristic curve analysis was used to determine the diagnostic accuracy of CD activity. Of the 47 patients, 25 were active CD (CDAI≥150) and 22 were inactive (CDAI<150). Diffusion-weighted MR imaging and MRE + DWI scores of active CD were significantly higher than that of inactive CD (both P < 0.001). Apparent diffusion coefficients in inflamed segments of active CD were lower than that of inactive CD (P < 0.001). The DWI scores (r = 0.74, P < 0.001), ADCs (r = -0.71, P < 0.001), MRE scores (r = 0.54, P < 0.001), and MRE + DWI scores (r = 0.66, P < 0.001) were all correlated with CDAI. The areas under the receiver-operating characteristics curves for ADCs, DWI scores, MRE scores, and MRE + DWI scores ranged from 0.83 to 0.98. The threshold ADC value of 1.17 × 10 mm/s allowed differentiation of active from inactive CD with 100% sensitivity and 88% specificity. Diffusion-weighted MR imaging and ADC correlated with CD activity, and had excellent diagnostic accuracy for differentiating active from inactive CD. PMID:26512584

  19. [Ovarian metastases from ventricular cancer diagnosed using diffusion-weighted 3T magnetic resonance imaging].

    PubMed

    Røhl, Lisbeth; Nellemann, Hanne Marie; Ladekarl, Morten; Pedersen, Erik Morre

    2011-04-18

    A 58-year-old female with a non-resectable ventricular cancer was followed by conventional 3.0 T magnetic resonance imaging (MRI) of the pelvis and abdomen including diffusion-weighted MR imaging (DWI). B-values were 0 and 1,000 seconds/mm2, and the apparent diffusion coefficient was calculated. At one control, ovarian metastases were detected by DWI, but did not show on conventional T2 and T1. The ovarian metastases were surgically removed and histologically verified - even though metastasectomy is controversial. In conclusion, DWI at 3.0 T is feasible and can improve the detection of metastatic disease compared with conventional MRI. PMID:21501566

  20. Updates in advanced diffusion-weighted magnetic resonance imaging techniques in the evaluation of prostate cancer

    PubMed Central

    Vargas, Hebert Alberto; Lawrence, Edward Malnor; Mazaheri, Yousef; Sala, Evis

    2015-01-01

    Diffusion-weighted magnetic resonance imaging (DW-MRI) is considered part of the standard imaging protocol for the evaluation of patients with prostate cancer. It has been proven valuable as a functional tool for qualitative and quantitative analysis of prostate cancer beyond anatomical MRI sequences such as T2-weighted imaging. This review discusses ongoing controversies in DW-MRI acquisition, including the optimal number of b-values to be used for prostate DWI, and summarizes the current literature on the use of advanced DW-MRI techniques. These include intravoxel incoherent motion imaging, which better accounts for the non-mono-exponential behavior of the apparent diffusion coefficient as a function of b-value and the influence of perfusion at low b-values. Another technique is diffusion kurtosis imaging (DKI). Metrics from DKI reflect excess kurtosis of tissues, representing its deviation from Gaussian diffusion behavior. Preliminary results suggest that DKI findings may have more value than findings from conventional DW-MRI for the assessment of prostate cancer. PMID:26339460

  1. Diffusion weighted MR imaging in the differential diagnosis of haemangiomas and metastases of the liver

    PubMed Central

    Inan, Nagihan; Kilinc, Furkan; Sarisoy, Tahsin; Gumustas, Sevtap; Akansel, Gur; Demirci, Ali

    2010-01-01

    Background The purpose of the study was to evaluate the value of diffusion-weighted imaging in the differential diagnosis of haemangiomas from metastases of the liver. Patients and methods. We analyzed 69 lesions in 38 patients (33 haemangiomas; 36 metastases) in the retrospective study. Diffusion-weighted imaging was performed using a breath-hold single-shot echo-planar spin echo sequence with three b factors (0, 500 and 1000 sec/mm2), and apparent diffusion coefficients (ADCs) were calculated. For the quantitative evaluation, signal intensity of the lesions, lesion-to-liver signal intensity ratios, ADC of the lesions, and lesion-to-liver ADC ratios were compared between the groups. The statistical significance was determined by student’s-t test. Results With the b factor 500 sec/mm2, no statistical significance was achieved (p>0.05). With the b factor of 1000 sec/mm2, both the signal intensity and lesion-to-liver signal intensity ratio of the metastases were significantly higher than those for haemangiomas (p<0.001). The cut-off value at 2.6 yielded a sensitivity of 86% and a specificity of 82% for the lesion-to-liver signal intensity ratio. The ADC, and lesion-to-liver ADC ratio of the metastases were significantly lower than those of haemangiomas (p<0.001). With cut-off value of 1.7, ADC ratio had a sensitivity of 88% and a specificity of 72% for ADC lesion/liver. Conclusions Diffusion-weighted imaging with high b value may help in the differential diagnosis of metastases from haemangiomas of the liver. PMID:22933887

  2. Differentiation of malignant and benign lung lesions with diffusion-weighted MR imaging

    PubMed Central

    Gümüştaş, Sevtap; Inan, Nagihan; Akansel, Gür; Çiftçi, Ercüment; Demirci, Ali; Özkara, Sevgiye Kaçar

    2012-01-01

    Background The aim of the study was to evaluate the role of diffusion-weighted magnetic resonance imaging in the differential diagnosis of lung lesions. Patients and methods. Sixty-seven patients with lung lesions (48 malignant, 19 benign) were included in this prospective study. Signal intensities (SIs) were measured in diffusion-weighted MR images that were obtained with b=0, 500 and 1000 s/mm2 values. Apparent diffusion coefficient (ADC) maps were calculated by using images with b=0 and 1000 s/mm2 values. The statistical significance was determined using the Student-t test. Results The SIs of malignant lesions were significantly higher than those of benign lesions (p<0.004 for b=0 s/mm2 and p<0.000 for the other b values). Using b=500 s/mm2, SI≥391 indicated a malignant lesion with a sensitivity of 95%, specificity of 73% and positive predictive value of 87%. Using b=1000 s/mm2, SI≥277 indicated a malignant lesion with a sensitivity of 93%, specificity of 69% and positive predictive value of 85%. There was no significant difference between malignant and benign lesions regarding ADC values (p=0.675). There was no significant difference in SIs or ADC values between small cell carcinoma and non-small cell carcinoma. When comparing undifferentiated with well- partially differentiated cancers, SIs were higher with all b values, but the difference was statistically significant only with b=1000 s/mm2 (p<0.04). Conclusions Diffusion-weighteted MR trace image SI is useful for the differentiation of malignant versus benign lung lesions. PMID:23077446

  3. Information-based ranking of 10 compartment models of diffusion-weighted signal attenuation in fixed prostate tissue.

    PubMed

    Liang, Sisi; Panagiotaki, Eleftheria; Bongers, Andre; Shi, Peng; Sved, Paul; Watson, Geoffrey; Bourne, Roger

    2016-05-01

    This study compares the theoretical information content of single- and multi-compartment models of diffusion-weighted signal attenuation in prostate tissue. Diffusion-weighted imaging (DWI) was performed at 9.4 T with multiple diffusion times and an extended range of b values in four whole formalin-fixed prostates. Ten models, including different combinations of isotropic, anisotropic and restricted components, were tested. Models were ranked using the Akaike information criterion. In all four prostates, two-component models, comprising an anisotropic Gaussian component and an isotropic restricted component, ranked highest in the majority of voxels. Single-component models, whether isotropic (apparent diffusion coefficient, ADC) or anisotropic (diffusion tensor imaging, DTI), consistently ranked lower than multi-component models. Model ranking trends were independent of voxel size and maximum b value in the range tested (1.6-16 mm(3) and 3000-10 000 s/mm(2) ). This study characterizes the two major water components previously identified by biexponential models and shows that models incorporating both anisotropic and restricted components provide more information-rich descriptions of DWI signals in prostate tissue than single- or multi-component anisotropic models and models that do not account for restricted diffusion. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26999065

  4. Value of 3 Tesla diffusion-weighted magnetic resonance imaging for assessing liver fibrosis

    PubMed Central

    Papalavrentios, Lavrentios; Sinakos, Emmanouil; Chourmouzi, Danai; Hytiroglou, Prodromos; Drevelegas, Konstantinos; Constantinides, Manos; Drevelegas, Antonios; Talwalkar, Jayant; Akriviadis, Evangelos

    2015-01-01

    Background Limited data are available regarding the role of magnetic resonance imaging (MRI), particularly the new generation 3 Tesla technology, and especially diffusion-weighted imaging (DWI) in predicting liver fibrosis. The aim of our pilot study was to assess the clinical performance of the apparent diffusion coefficient (ADC) of liver parenchyma for the assessment of liver fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). Methods 18 patients with biopsy-proven NAFLD underwent DWI with 3 Tesla MRI. DWI was performed with single-shot echo-planar technique at b values of 0-500 and 0-1000 s/mm2. ADC was measured in four locations in the liver and the mean ADC value was used for analysis. Staging of fibrosis was performed according to the METAVIR system. Results The median age of patients was 52 years (range 23-73). The distribution of patients in different fibrosis stages was: 0 (n=1), 1 (n=7), 2 (n=1), 3 (n=5), 4 (n=4). Fibrosis stage was poorly associated with ADC at b value of 0-500 s/mm2 (r= -0.30, P=0.27). However it was significantly associated with ADC at b value of 0-1000 s/mm2 (r= -0.57, P=0.01). For this b value (0-1000 s/mm2) the area under receiver-operating characteristic curve was 0.93 for fibrosis stage ≥3 and the optimal ADC cut-off value was 1.16 ×10-3 mm2/s. Conclusion 3 Tesla DWI can possibly predict the presence of advanced fibrosis in patients with NAFLD. PMID:25608776

  5. Reversible diffusion weighted imaging changes in propionic acidemia.

    PubMed

    Kandel, Amit; Amatya, Sirisa Kandel; Yeh, E Ann

    2013-01-01

    Propionic acidemia is an inborn error of metabolism with neurologic manifestations. We describe a 3-year-old boy with propionic acidemia presenting with a metabolic crisis including headache, vomiting, and altered mental status with metabolic acidosis. Electroencephalography showed focal slowing in right temporal region. Magnetic resonance imaging (MRI) of the brain showed restricted diffusion with apparent diffusion coefficient correlate in the right parietooccipital region. Correction of metabolic acidosis led to clinical improvement and normalization of MRI diffusion weighted imaging/apparent diffusion coefficient changes. This article suggests that restricted diffusion resulting from metabolic crises in propionic acidemia may be reversible in some cases. PMID:22532545

  6. ADC values in diffusion-weighted MRI and their relationship with age, gender and BMI in healthy people's pancreases

    PubMed Central

    Faeghi, F; Abdkarimi, M H; Asghari JafarAbadi, M

    2015-01-01

    Objective: The aim of this study is to use diffusion-weighted MRI to assess the apparent diffusion coefficient (ADC) values in head, body and tail sections of the pancreas in healthy subjects and the relationships between these values and age, gender and body mass index (BMI) of these cases. Methods: This study was conducted on 82 participants who were referred to the Tabesh Medical Imaging Center, Tabriz, Islamic Republic of Iran, during 2013. Echo-planar diffusion-weighted imaging of the pancreas was carried out with b-values of 50, 400 and 800 s mm−2, and ADC values were assessed for the head, body and tail sections of the pancreas. Results: The ADC values for the head, body and tail sections of the pancreas in female participants were significantly greater than those in male subjects (p < 0.05). ADC values for these parts among subjects with different BMI differed significantly (p < 0.05). Regarding age, there were no statistically meaningful differences among the ADC values for the three parts (p > 0.05). Conclusion: Gender and BMI effect the ADC values of the three sections of the pancreas. Thus, knowledge of the basic values based on gender and BMI can improve diagnostics. Having looked at age factor, it seems that the ADC values were not significantly different. Advances in knowledge: According to the results pancreatic ADC values appear to be influenced by gender and BMI but not by age. PMID:25471056

  7. Diffusion-weighted MRI in the evaluation of renal lesions: preliminary results.

    PubMed

    Cova, M; Squillaci, E; Stacul, F; Manenti, G; Gava, S; Simonetti, G; Pozzi-Mucelli, R

    2004-10-01

    The purpose of this study was to evaluate the capability and the reliability of diffusion-weighted MRI in the evaluation of normal kidney and different renal lesions. 39 patients (10 normal volunteers and 29 patients with known renal lesions) underwent MRI of the kidneys by using a 1.5 T superconducting magnet. Axial fat suppressed turbo spin echo (TSE) T(2) and coronal fast field echo (FFE) T(1) or TSE T(1) weighted images were acquired for each patient. Diffusion-weighted (DW) images were obtained in the axial plane during breath-hold (17 s) with a spin-echo echo planar imaging (SE EPI) single shot sequence (repetition time (TR)=2883 ms, echo time (TE)=61 ms, flip angle=90 degrees ), with b value of 500 s mm(-2). 16 slices were produced with slice thickness of 7 mm and interslice gap of 1 mm. An apparent diffusion coefficient (ADC) map was obtained at each slice position. The ADC was measured in an approximately 1 cm region of interest (ROI) within the normal renal parenchyma, the detected renal lesions and the collecting system if dilated. ADC values in normal renal parenchyma ranged from 1.72 x 10(-3) mm(2) s(-1) to 2.65 x 10(-3) mm(2) s(-1), while ADC values in simple cysts (n=13) were higher (2.87 x 10(-3) mm(2) s(-1) to 4.00 x 10(-3) mm(2) s(-1)). In hydronephrotic kidneys (n=6) the ADC values of renal pelvis ranged from 3.39 x 10(-3) mm(2) s(-1) to 4.00 x 10(-3) mm(2) s(-1). In cases of pyonephrosis (n=3) ADC values of the renal pelvis were found to be lower than those of renal pelvis of hydronephrotic kidneys (0.77 x 10(-3) mm(2) s(-1) to 1.07 x 10(-3) mm(2) s(-1)). Solid benign and malignant renal tumours (n=7) showed ADC values ranging between 1.28 x 10(-3) mm(2) s(-1) and 1.83 x 10(-3) mm(2) s(-1). In conclusion diffusion-weighted MR imaging of the kidney seems to be a reliable way to differentiate normal renal parenchyma and different renal diseases. Clinical experience with this method is still preliminary and further studies are required. PMID

  8. Diffusion-Weighted Magnetic Resonance Imaging in Monitoring Rectal Cancer Response to Neoadjuvant Chemoradiotherapy

    SciTech Connect

    Barbaro, Brunella; Vitale, Renata; Valentini, Vincenzo; Illuminati, Sonia; Vecchio, Fabio M.; Rizzo, Gianluca; Gambacorta, Maria Antonietta; Coco, Claudio; Crucitti, Antonio; Persiani, Roberto; Sofo, Luigi; Bonomo, Lorenzo

    2012-06-01

    Purpose: To prospectively monitor the response in patients with locally advanced nonmucinous rectal cancer after chemoradiotherapy (CRT) using diffusion-weighted magnetic resonance imaging. The histopathologic finding was the reference standard. Methods and Materials: The institutional review board approved the present study. A total of 62 patients (43 men and 19 women; mean age, 64 years; range, 28-83) provided informed consent. T{sub 2}- and diffusion-weighted magnetic resonance imaging scans (b value, 0 and 1,000 mm{sup 2}/s) were acquired before, during (mean 12 days), and 6-8 weeks after CRT. We compared the median apparent diffusion coefficients (ADCs) between responders and nonresponders and examined the associations with the Mandard tumor regression grade (TRG). The postoperative nodal status (ypN) was evaluated. The Mann-Whitney/Wilcoxon two-sample test was used to evaluate the relationships among the pretherapy ADCs, extramural vascular invasion, early percentage of increases in ADCs, and preoperative ADCs. Results: Low pretreatment ADCs (<1.0 Multiplication-Sign 10{sup -3}mm{sup 2}/s) were correlated with TRG 4 scores (p = .0011) and associated to extramural vascular invasion with ypN+ (85.7% positive predictive value for ypN+). During treatment, the mean percentage of increase in tumor ADC was significantly greater in the responders than in the nonresponders (p < .0001) and a >23% ADC increase had a 96.3% negative predictive value for TRG 4. In 9 of 16 complete responders, CRT-related tumor downsizing prevented ADC evaluations. The preoperative ADCs were significantly different (p = .0012) between the patients with and without downstaging (preoperative ADC {>=}1.4 Multiplication-Sign 10{sup -3}mm{sup 2}/s showed a positive and negative predictive value of 78.9% and 61.8%, respectively, for response assessment). The TRG 1 and TRG 2-4 groups were not significantly different. Conclusion: Diffusion-weighted magnetic resonance imaging seems to be a promising

  9. Diffusion-weighted imaging in pediatric body MR imaging: principles, technique, and emerging applications.

    PubMed

    Chavhan, Govind B; Alsabban, Zehour; Babyn, Paul S

    2014-01-01

    Diffusion-weighted (DW) imaging is an emerging technique in body imaging that provides indirect information about the microenvironment of tissues and lesions and helps detect, characterize, and follow up abnormalities. Two main challenges in the application of DW imaging to body imaging are the decreased signal-to-noise ratio of body tissues compared with neuronal tissues due to their shorter T2 relaxation time, and image degradation related to physiologic motion (eg, respiratory motion). Use of smaller b values and newer motion compensation techniques allow the evaluation of anatomic structures with DW imaging. DW imaging can be performed as a breath-hold sequence or a free-breathing sequence with or without respiratory triggering. Depending on the mobility of water molecules in their microenvironment, different normal tissues have different signals at DW imaging. Some normal tissues (eg, lymph nodes, spleen, ovarian and testicular parenchyma) are diffusion restricted, whereas others (eg, gallbladder, corpora cavernosa, endometrium, cartilage) show T2 shine-through. Epiphyses that contain fatty marrow and bone cortex appear dark on both DW images and apparent diffusion coefficient maps. Current and emerging applications of DW imaging in pediatric body imaging include tumor detection and characterization, assessment of therapy response and monitoring of tumors, noninvasive detection and grading of liver fibrosis and cirrhosis, detection of abscesses, and evaluation of inflammatory bowel disease. PMID:24819803

  10. Diagnostic utility of diffusion-weighted magnetic resonance imaging in two common renal tumors

    PubMed Central

    WEN, ZHAOXIA; SUN, ZHENCHAO; WANG, YUXING

    2015-01-01

    The aim of the present study was to evaluate the utility of diffusion-weighted magnetic resonance imaging (DWI) in the diagnosis of common renal tumors. Conventional magnetic resonance imaging and DWI were performed on 85 patients with renal lesions (54 renal carcinoma and 31 renal angiomyolipoma cases). The apparent diffusion coefficient (ADC) values in each case at b=800 sec/mm2 were measured in the ADC maps using a statistical software package. The 54 cases of renal cell carcinoma showed a high signal intensity in the parenchyma, and the 31 renal angiomyolipoma cases showed a well-defined mixed signal intensity on DWI. The soft-tissue component showed a high signal intensity and the fat tissue showed a low signal intensity on DWI. When the b-value was set to 800 sec/mm2, the mean ADC was significantly lower in the renal carcinoma cases than in the renal angiomyolipoma cases. In conclusion, the measurement of ADC on DWI can reveal the structure of renal tumors, which is beneficial in diagnosing and determining the prognosis of benign and malignant renal tumors. PMID:26622890

  11. MR diffusion-weighted imaging of kidney: differentiation between hydronephrosis and pyonephrosis.

    PubMed

    Chan, J H; Tsui, E Y; Luk, S H; Fung, S L; Cheung, Y K; Chan, M S; Yuen, M K; Mak, S F; Wong, K P

    2001-01-01

    The objective of the study was to evaluate the capability and reliability of the magnetic resonance (MR) diffusion-weighted imaging (DWI) in differentiation between hydronephrosis and pyonephrosis. Single-shot echoplanar MR diffusion-weighted imaging was performed in 12 patients who had dilatation of the renal pelvis and calyces detected by ultrasonography (US). Microbiological tests confirmed that there were four cases of pyonephrosis and eight cases of hydronephrosis. Signal intensities of the collecting (pelvicalyceal) systems on the diffusion-weighted images and apparent diffusion coefficient (ADC) maps were noted. ADC values of the pelvicalyceal system in all patients were computed and compared using Student's t test. On diffusion-weighted images, the pelvicalyceal system of the hydronephrotic kidney was hypointense while the pelvicalyceal system of the pyonephrotic kidney was markedly hyperintense. The mean ADCs of the hydronephrotic and pyonephrotic renal pelvis were 2.98 +/- 0.65 x 10(-3) and 0.64 +/- 0.35 x 10(-3) mm(2)/s, respectively. The extremely low ADC of the renal pelvis of the pyonephrotic kidney accounted for its signal hyperintensity on diffusion-weighted images as well as signal hypointensity on ADC maps. In conclusion, the MR diffusion-weighted imaging may be a reliable tool to differentiate pyonephrosis from hydronephrosis. PMID:11483420

  12. High b value DWI in evaluation of the hyperacute cerebral ischemia at 3T: A comparative study in an embolic canine stroke model

    PubMed Central

    Cheng, Qiguang; Xu, Xiaoquan; Zu, Qingquan; Lu, Shanshan; Yu, Jing; Liu, Xinglong; Wang, Bin; Shi, Haibin; Teng, Gaojun; Liu, Sheng

    2016-01-01

    Previous studies have indicated that the temporal change of relative diffusion weighted imaging (rDWI) signal intensity may help to determine the onset time of a stroke. Furthermore, several studies have indicated that high b value DWI offered improved detection rates for hyper-acute ischemic lesions compared with standard b value DWI. However, the temporal changes of the rDWI on high b value DWI remain unclear. Therefore, based on our embolic canine stroke model, we evaluated the temporal evolution of rDWI on high b value DWI, and further compared its diagnostic value in predicting the onset time of ischemic stroke with rDWI on standard b value DWI. Twelve canine MCAO models were established, and DWI was performed at 1, 2, 3, 4, 5 and 6 h after MCAO, with 3 b values of 1,000, 2,000 and 3,000. High b value DWI detected all ischemic lesions after 1 h, while standard b value did not detect the ischemic lesions in one dog at 1 h. With all three of the tested b values, rDWIs increased continuously within 6 h, while relative apparent diffusion coefficient (rADC) values rapidly decreased in 1 h, then became relatively stable. The area under the curve values for rDWI with b value of 1,000, 2,000 and 3,000, in predicting ischemic lesions within 3 h were 0.897, 0.929 and 0.938, while for rADC were 0.645, 0.583 and 0.599, respectively. Therefore, the results indicated that the rDWI was helpful in aging hyper-acute ischemic stroke, while rADC appeared not to be. High b value DWI had a higher detection rate for ischemic lesions and better predictive efficacy in determining the onset time of hyper-acute stroke. PMID:27446301

  13. A comparative quantitative analysis of magnetic susceptibility artifacts in echo planar and PROPELLER diffusion-weighted images

    NASA Astrophysics Data System (ADS)

    Cho, Jae-Hwan; Lee, Hae-Kag; Yang, Han-Joon; Lee, Gui-Won; Park, Yong-Soon; Chung, Woon-Kwan

    2013-01-01

    In this study, the authors investigated whether periodically-rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion-weighted imaging (DWI) can remove magnetic susceptibility artifacts and compared apparent diffusion coefficient (ADC) values for PROPELLER DWI and the common echo planar (EP) DWI. Twenty patients that underwent brain MRI with a metal dental implant were selected. A 3.0T MR scanner was then used to obtain EP DWI, PROPELLER DWI, and corresponding apparent diffusion coefficient (ADC) maps for a b-value of 0 and 1,000 s/mm2. The frequencies of magnetic susceptibility artifacts in four parts of the brain (bilateral temporal lobes, pons, and orbit) were selected. In the ADC maps, we measured the ADC values of both sides of the temporal lobe and the pons. According to the study results, the frequency of magnetic susceptibility artifacts in PROPELLER DW images was lower than it was in EP DW images. In ADC maps, the ADC values of the bilateral temporal lobes and the pons were all higher in PROPELLER ADC maps than in EP ADC maps. Our findings show that when a high-field MRI machine is used, magnetic susceptibility artifacts can distort anatomical structures and produce high-intensity signals. Furthermore, our findings suggest that in many cases, PROPELLER DWI would be helpful in terms of achieving a correct diagnosis.

  14. Diffusion-Weighted MRI of Malignant versus Benign Portal Vein Thrombosis

    PubMed Central

    Ahn, Jhii-Hyun; Cho, Eun-Suk; Chung, Jae-Joon; Kim, Joo Hee; Kim, Ki Whang

    2016-01-01

    Objective To validate the diffusion-weighted MRI (DWI) for differentiation of benign from malignant portal vein thrombosis. Materials and Methods The Institutional Review Board approved this retrospective study and waived informed consent. A total of 59 consecutive patients (52 men and 7 women, aged 40–85 years) with grossly defined portal vein thrombus (PVT) on hepatic MRI were retrospectively analyzed. Among them, liver cirrhosis was found in 45 patients, and hepatocellular carcinoma in 47 patients. DWI was performed using b values of 50 and 800 sec/mm2 at 1.5-T unit. A thrombus was considered malignant if it enhanced on dynamic CT or MRI; otherwise, it was considered bland. There were 18 bland thrombi and 49 malignant thrombi in 59 patients, including 8 patients with simultaneous benign and malignant PVT. Mean apparent diffusion coefficients (ADCs) of benign and malignant PVTs were compared by using Mann-Whitney U test. Diagnostic accuracy was evaluated using receiver operating characteristic (ROC) curve analysis. Results The mean ADC ± standard deviation of bland and malignant PVT were 1.00 ± 0.39 × 10-3 mm2/sec and 0.92 ± 0.25 × 10-3 mm2/sec, respectively; without significant difference (p = 0.799). The area under ROC curve for ADC was 0.520. An ADC value of > 1.35 × 10-3 mm2/sec predicted bland PVT with a specificity of 94.6% (95% confidence interval [CI]: 84.9–98.9%) and a sensitivity of 22.2% (95% CI: 6.4–47.6%), respectively. Conclusion Due to the wide range and considerable overlap of the ADCs, DWI cannot differentiate the benign from malignant thrombi efficiently. PMID:27390544

  15. 3T diffusion-weighted MRI of the thyroid gland with reduced distortion: preliminary results

    PubMed Central

    Nagala, S; Priest, A N; McLean, M A; Jani, P; Graves, M J

    2013-01-01

    Objective: Single-shot diffusion-weighted (DW) echo planar imaging (EPI), which is commonly used for imaging the thyroid, is characterised by severe blurring and distortion. The objectives of this work were: 1, to show that a reduced-field of view (r-FOV) DW EPI technique can improve image quality; and 2, to investigate the effect of different reconstruction strategies on the resulting apparent diffusion coefficients (ADCs). Methods: We implemented a single-shot, r-FOV DW EPI technique with a two-dimensional radiofrequency excitation pulse for DW imaging of the thyroid at 3T. Images were reconstructed using root sum of squares (SOS) and an optimal-B1 reconstruction (OBR). Phantom and in vivo experiments were performed to compare r-FOV and conventional full-FOV DW EPI with root SOS and OBR. Results: r-FOV with OBR substantially improved image quality at 3T. In phantoms, r-FOV gave more accurate ADCs than full-FOV. In vivo r-FOV always gave lower ADC values with respect to the full-FOV technique irrespective of the reconstruction used and whether only two or multiple b-values were used to compute the ADCs. Conclusion: r-FOV DW EPI can reduce image blurring and distortion at the expense of a low signal-to-noise ratio. OBR is a promising reconstruction technique for accurate ADC measurements in lower signal-to-noise ratio regimes, although further studies are needed to characterise its performance. Advances in knowledge: DW imaging of the thyroid at 3T could potentially benefit from r-FOV acquisition strategies, such as the r-FOV DW EPI technique proposed in this paper. PMID:23770539

  16. Diffusion weighted vertical gradient and spin echo.

    PubMed

    Engström, Mathias; Bammer, Roland; Skare, Stefan

    2012-12-01

    In this work, diffusion weighting and parallel imaging is combined with a vertical gradient and spin echo data readout. This sequence was implemented and evaluated on healthy volunteers using a 1.5 and a 3 T whole-body MR system. As the vertical gradient and spin echo trajectory enables a higher k-space velocity in the phase-encoding direction than single-shot echo planar imaging, the geometrical distortions are reduced. When combined with parallel imaging such as generalized autocalibrating partially parallel acquisition, the geometric distortions are reduced even further, while also keeping the minimum echo time reasonably low. However, this combination of a diffusion preparation and multiple refocusing pulses during the vertical gradient and spin echo readout, generally violates the Carr-Purcell-Meiboom-Gill condition, which leads to interferences between echo pathways. To suppress the stimulated echo pathway, refocusing pulses with a sharper slice profiles and an odd/even crusher variation scheme were implemented and evaluated. Being a single-shot acquisition technique, the reconstructed images are robust to rigid-body head motion and spatially varying brain motion, both of which are common sources of artifacts in diffusion MRI. PMID:23008151

  17. Quality Control of Diffusion Weighted Images

    PubMed Central

    Liu, Zhexing; Wang, Yi; Gerig, Guido; Gouttard, Sylvain; Tao, Ran; Fletcher, Thomas; Styner, Martin

    2013-01-01

    Diffusion Tensor Imaging (DTI) has become an important MRI procedure to investigate the integrity of white matter in brain in vivo. DTI is estimated from a series of acquired Diffusion Weighted Imaging (DWI) volumes. DWI data suffers from inherent low SNR, overall long scanning time of multiple directional encoding with correspondingly large risk to encounter several kinds of artifacts. These artifacts can be too severe for a correct and stable estimation of the diffusion tensor. Thus, a quality control (QC) procedure is absolutely necessary for DTI studies. Currently, routine DTI QC procedures are conducted manually by visually checking the DWI data set in a gradient by gradient and slice by slice way. The results often suffer from low consistence across different data sets, lack of agreement of different experts, and difficulty to judge motion artifacts by qualitative inspection. Additionally considerable manpower is needed for this step due to the large number of images to QC, which is common for group comparison and longitudinal studies, especially with increasing number of diffusion gradient directions. We present a framework for automatic DWI QC. We developed a tool called DTIPrep which pipelines the QC steps with a detailed protocoling and reporting facility. And it is fully open source. This framework/tool has been successfully applied to several DTI studies with several hundred DWIs in our lab as well as collaborating labs in Utah and Iowa. In our studies, the tool provides a crucial piece for robust DTI analysis in brain white matter study. PMID:24353379

  18. Diffusion-weighted imaging of pancreatic cancer.

    PubMed

    De Robertis, Riccardo; Tinazzi Martini, Paolo; Demozzi, Emanuele; Dal Corso, Flavia; Bassi, Claudio; Pederzoli, Paolo; D'Onofrio, Mirko

    2015-10-28

    Magnetic resonance imaging (MRI) is a reliable and accurate imaging method for the evaluation of patients with pancreatic ductal adenocarcinoma (PDAC). Diffusion-weighted imaging (DWI) is a relatively recent technological improvement that expanded MRI capabilities, having brought functional aspects into conventional morphologic MRI evaluation. DWI can depict the random diffusion of water molecules within tissues (the so-called Brownian motions). Modifications of water diffusion induced by different factors acting on the extracellular and intracellular spaces, as increased cell density, edema, fibrosis, or altered functionality of cell membranes, can be detected using this MR sequence. The intravoxel incoherent motion (IVIM) model is an advanced DWI technique that consent a separate quantitative evaluation of all the microscopic random motions that contribute to DWI, which are essentially represented by molecular diffusion and blood microcirculation (perfusion). Technological improvements have made possible the routine use of DWI during abdominal MRI study. Several authors have reported that the addition of DWI sequence can be of value for the evaluation of patients with PDAC, especially improving the staging; nevertheless, it is still unclear whether and how DWI could be helpful for identification, characterization, prognostic stratification and follow-up during treatment. The aim of this paper is to review up-to-date literature data regarding the applications of DWI and IVIM to PDACs. PMID:26516428

  19. Diffusion-weighted imaging of pancreatic cancer

    PubMed Central

    De Robertis, Riccardo; Tinazzi Martini, Paolo; Demozzi, Emanuele; Dal Corso, Flavia; Bassi, Claudio; Pederzoli, Paolo; D’Onofrio, Mirko

    2015-01-01

    Magnetic resonance imaging (MRI) is a reliable and accurate imaging method for the evaluation of patients with pancreatic ductal adenocarcinoma (PDAC). Diffusion-weighted imaging (DWI) is a relatively recent technological improvement that expanded MRI capabilities, having brought functional aspects into conventional morphologic MRI evaluation. DWI can depict the random diffusion of water molecules within tissues (the so-called Brownian motions). Modifications of water diffusion induced by different factors acting on the extracellular and intracellular spaces, as increased cell density, edema, fibrosis, or altered functionality of cell membranes, can be detected using this MR sequence. The intravoxel incoherent motion (IVIM) model is an advanced DWI technique that consent a separate quantitative evaluation of all the microscopic random motions that contribute to DWI, which are essentially represented by molecular diffusion and blood microcirculation (perfusion). Technological improvements have made possible the routine use of DWI during abdominal MRI study. Several authors have reported that the addition of DWI sequence can be of value for the evaluation of patients with PDAC, especially improving the staging; nevertheless, it is still unclear whether and how DWI could be helpful for identification, characterization, prognostic stratification and follow-up during treatment. The aim of this paper is to review up-to-date literature data regarding the applications of DWI and IVIM to PDACs. PMID:26516428

  20. Separation of extra- and intracellular metabolites using hyperpolarized 13C diffusion weighted MR

    NASA Astrophysics Data System (ADS)

    Koelsch, Bertram L.; Sriram, Renuka; Keshari, Kayvan R.; Leon Swisher, Christine; Van Criekinge, Mark; Sukumar, Subramaniam; Vigneron, Daniel B.; Wang, Zhen J.; Larson, Peder E. Z.; Kurhanewicz, John

    2016-09-01

    This work demonstrates the separation of extra- and intracellular components of glycolytic metabolites with diffusion weighted hyperpolarized 13C magnetic resonance spectroscopy. Using b-values of up to 15,000 s mm-2, a multi-exponential signal response was measured for hyperpolarized [1-13C] pyruvate and lactate. By fitting the fast and slow asymptotes of these curves, their extra- and intracellular weighted diffusion coefficients were determined in cells perfused in a MR compatible bioreactor. In addition to measuring intracellular weighted diffusion, extra- and intracellular weighted hyperpolarized 13C metabolites pools are assessed in real-time, including their modulation with inhibition of monocarboxylate transporters. These studies demonstrate the ability to simultaneously assess membrane transport in addition to enzymatic activity with the use of diffusion weighted hyperpolarized 13C MR. This technique could be an indispensible tool to evaluate the impact of microenvironment on the presence, aggressiveness and metastatic potential of a variety of cancers.

  1. Separation of extra- and intracellular metabolites using hyperpolarized (13)C diffusion weighted MR.

    PubMed

    Koelsch, Bertram L; Sriram, Renuka; Keshari, Kayvan R; Leon Swisher, Christine; Van Criekinge, Mark; Sukumar, Subramaniam; Vigneron, Daniel B; Wang, Zhen J; Larson, Peder E Z; Kurhanewicz, John

    2016-09-01

    This work demonstrates the separation of extra- and intracellular components of glycolytic metabolites with diffusion weighted hyperpolarized (13)C magnetic resonance spectroscopy. Using b-values of up to 15,000smm(-2), a multi-exponential signal response was measured for hyperpolarized [1-(13)C] pyruvate and lactate. By fitting the fast and slow asymptotes of these curves, their extra- and intracellular weighted diffusion coefficients were determined in cells perfused in a MR compatible bioreactor. In addition to measuring intracellular weighted diffusion, extra- and intracellular weighted hyperpolarized (13)C metabolites pools are assessed in real-time, including their modulation with inhibition of monocarboxylate transporters. These studies demonstrate the ability to simultaneously assess membrane transport in addition to enzymatic activity with the use of diffusion weighted hyperpolarized (13)C MR. This technique could be an indispensible tool to evaluate the impact of microenvironment on the presence, aggressiveness and metastatic potential of a variety of cancers. PMID:27434780

  2. Interpolation of diffusion weighted imaging datasets.

    PubMed

    Dyrby, Tim B; Lundell, Henrik; Burke, Mark W; Reislev, Nina L; Paulson, Olaf B; Ptito, Maurice; Siebner, Hartwig R

    2014-12-01

    Diffusion weighted imaging (DWI) is used to study white-matter fibre organisation, orientation and structural connectivity by means of fibre reconstruction algorithms and tractography. For clinical settings, limited scan time compromises the possibilities to achieve high image resolution for finer anatomical details and signal-to-noise-ratio for reliable fibre reconstruction. We assessed the potential benefits of interpolating DWI datasets to a higher image resolution before fibre reconstruction using a diffusion tensor model. Simulations of straight and curved crossing tracts smaller than or equal to the voxel size showed that conventional higher-order interpolation methods improved the geometrical representation of white-matter tracts with reduced partial-volume-effect (PVE), except at tract boundaries. Simulations and interpolation of ex-vivo monkey brain DWI datasets revealed that conventional interpolation methods fail to disentangle fine anatomical details if PVE is too pronounced in the original data. As for validation we used ex-vivo DWI datasets acquired at various image resolutions as well as Nissl-stained sections. Increasing the image resolution by a factor of eight yielded finer geometrical resolution and more anatomical details in complex regions such as tract boundaries and cortical layers, which are normally only visualized at higher image resolutions. Similar results were found with typical clinical human DWI dataset. However, a possible bias in quantitative values imposed by the interpolation method used should be considered. The results indicate that conventional interpolation methods can be successfully applied to DWI datasets for mining anatomical details that are normally seen only at higher resolutions, which will aid in tractography and microstructural mapping of tissue compartments. PMID:25219332

  3. Diffusion-Weighted Magnetic Resonance Imaging Findings of Kidneys with Obstructive Uropathy: Differentiation between Benign and Malignant Etiology

    PubMed Central

    Apaydin, Melda; Sönmezgöz, Fitnet; Çalık, Sinan; Bedel Koruyucu, Melike

    2014-01-01

    Purpose. In this study, we aimed to evaluate the capability of diffusion-weighted magnetic resonance imaging (DWI) in differentiation between benign and malignant etiology of obstructive uropathy. Materials and Methods. DWI was performed in 41 patients with hydronephrotic kidneys and 26 healthy volunteers. MR imaging was performed using a 1.5 T whole-body superconducting MR scanner. The signal intensities of the renal parenchyma on DWI and apparent diffusion coefficient (ADC) maps were noted. DWI was performed with the following diffusion gradient b values: 100, 600, and 1000 s/mm2. A large circular region of interest was placed in the corticomedullary junction of the kidneys. For statistical analysis, the independent-samples t test was used. Results. The mean renal ADC values for b100, b600, and b1000 in hydronephrosis patients with benign and malignant etiology and the healthy volunteers of the control group were analysed. ADC measurements of renal parenchyma in all hydronephrotic kidneys with benign and malignant etiology were found to be statistically low compared to those of normal kidneys (P < 0.05). Conclusions. There were significant differences in the ADC values of obstructed kidneys compared to those of normal kidneys. Obstructed kidneys with malignant etiology had lower ADC values for b1000 compared to obstructed kidneys with benign etiology, but these alterations were statistically insignificant. PMID:24764775

  4. Multishot diffusion-weighted SPLICE PROPELLER MRI of the abdomen.

    PubMed

    Deng, Jie; Omary, Reed A; Larson, Andrew C

    2008-05-01

    Multishot FSE (fast spin echo)-based diffusion-weighted (DW)-PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) MRI offers the potential to reduce susceptibility artifacts associated with single-shot DW-EPI (echo-planar imaging) approaches. However, DW-PROPELLER in the abdomen is challenging due to the large field-of-view and respiratory motion during DW preparation. Incoherent signal phase due to motion will violate the Carr-Purcell-Meiboom-Gill (CPMG) conditions, leading to destructive interference between spin echo and stimulated echo signals and consequent signal cancellation. The SPLICE (split-echo acquisition of FSE signals) technique can mitigate non-CPMG artifacts in FSE-based sequences. For SPLICE, spin echo and stimulated echo are separated by using imbalanced readout gradients and extended acquisition window. Two signal families each with coherent phase properties are acquired at different intervals within the readout window. Separate reconstruction of these two signal families can avoid destructive phase interference. Phantom studies were performed to validate signal phase properties with different initial magnetization phases. This study evaluated the feasibility of combining SPLICE and PROPELLER for DW imaging of the abdomen. It is demonstrated that DW-SPLICE-PROPELLER can effectively mitigate non-CPMG artifacts and improve DW image quality and apparent diffusion coefficient (ADC) map homogeneity. PMID:18429036

  5. Diffusion-weighted MR imaging for characterizing musculoskeletal lesions.

    PubMed

    Subhawong, Ty K; Jacobs, Michael A; Fayad, Laura M

    2014-01-01

    Diffusion-weighted (DW) imaging is a functional magnetic resonance (MR) imaging technique that can readily be incorporated into a routine non-contrast material-enhanced MR imaging protocol with little additional scanning time. DW imaging is based on changes in the Brownian motion of water molecules caused by tissue microstructure. The apparent diffusion coefficient (ADC) is a quantitative measure of Brownian movement: Low ADC values typically reflect highly cellular microenvironments in which diffusion is restricted by the presence of cell membranes, whereas acellular regions allow free diffusion and result in elevated ADC values. Thus, with ADC mapping, one may derive useful quantitative information regarding the cellularity of a musculoskeletal lesion using a nonenhanced technique. The role of localized DW imaging in differentiating malignant from benign osseous and soft-tissue lesions is still evolving; when carefully applied, however, this modality has proved helpful in a subset of tumor types, such as nonmyxoid soft-tissue tumors. Studies of the use of DW imaging in assessing the treatment response of both osseous and soft-tissue tumors have shown that higher ADC values correlate with better response to cytotoxic therapy. Successful application of DW imaging in the evaluation of musculoskeletal lesions requires familiarity with potential diagnostic pitfalls that stem from technical artifacts and confounding factors unrelated to lesion cellularity. Further investigation is needed to evaluate the impact of DW imaging-ADC mapping on management and outcome in patients with musculoskeletal lesions. PMID:25208274

  6. Evaluation of thermal and cryo lesions by diffusion-weighted MRI

    NASA Astrophysics Data System (ADS)

    Chen, Jing; Daniel, Bruce; Bouley, Donna; Sommer, Graham; Butts Pauly, Kim

    2007-02-01

    The purpose of this study is to further investigate the approach of DWI to estimate the cell viability immediately after treatment. In this work, we reported the result from 12 canine prostate experiments underwent cryoablation or hyperthermic therapy. The lesion detected by diffusion-weighted imaging was evaluated through apparent diffusion coefficient (ADC) value, image contrast, and lesion contour compared to contrast enhanced imaging and histology.

  7. Diffusion-weighted magnetic resonance imaging in tubo-ovarian abscess: a case report.

    PubMed

    Takeshita, Tohru; Ninoi, Teruhisa; Doh, Kunihiko; Hashimoto, Shigeo; Inoue, Yuichi

    2009-12-01

    In this report, we describe the magnetic resonance imaging appearance of tubo-ovarian abscess (TOA) in a patient who underwent diffusion-weighted imaging (DWI) of the pelvis and subsequent histologic analysis. The content of the TOA was markedly high signal intensity relative to the surrounding tissue on DWI, and it showed low signal intensity on the apparent diffusion coefficient map; these findings were consistent with those of published reports on brain and liver abscesses. PMID:20088410

  8. A Computational Model for Diffusion Weighted Imaging of Myelinated White Matter

    PubMed Central

    Baxter, Gregory T.; Frank, Lawrence R.

    2013-01-01

    The signal for diffusion weighted magnetic resonance imaging has previously been represented analytically and simulated numerically for a variety of model problems with idealized geometries. Numerical simulations hold the promise of computing the diffusion weighted MR signal for more complex realistic tissue architectures and physiological models. This paper investigates a white matter model consisting of a matrix of coated cylinders with distinct diffusion coefficients and spin concentrations for each of the cylinder core, the coating, and the surrounding bath and compares results with an the analytical solution developed by Sen and Basser for the long diffusion time limit. Numerical simulations of diffusion weighted imaging experiments are performed for the three-medium model using a Monte Carlo diffusion simulation. Experiments are carried out for model parameters representing normal white matter. Pulse sequence parameters range from a low b value, long time limit, short pulse approximation to realistic clinical values. For simulations in the short pulse width, long diffusion time limit, numerical simulations agree with the Sen-Basser analytical result. When tested with realistic pulse sequence parameters, numerical simulations show lower anisotropy than the analytical model predicts. PMID:23507381

  9. Simple noise reduction for diffusion weighted images.

    PubMed

    Konishi, Yuto; Kanazawa, Yuki; Usuda, Takatoshi; Matsumoto, Yuki; Hayashi, Hiroaki; Matsuda, Tsuyoshi; Ueno, Junji; Harada, Masafumi

    2016-07-01

    Our purpose in this study was to reduce the noise in order to improve the SNR of Dw images with high b-value by using two correction schemes. This study was performed with use of phantoms made from water and sucrose at different concentrations, which were 10, 30, and 50 weight percent (wt%). In noise reduction for Dw imaging of the phantoms, we compared two correction schemes that are based on the Rician distribution and the Gaussian distribution. The highest error values for each concentration with use of the Rician distribution scheme were 7.3 % for 10 wt%, 2.4 % for 30 wt%, and 0.1 % for 50 wt%. The highest error values for each concentration with use of the Gaussian distribution scheme were 20.3 % for 10 wt%, 11.6 % for 30 wt%, and 3.4 % for 50 wt%. In Dw imaging, the noise reduction makes it possible to apply the correction scheme of Rician distribution. PMID:26984734

  10. Diffusion-weighted imaging of traumatic subdural hematoma in the subacute stage.

    PubMed

    Kuwahara, Seikou; Fukuoka, Masaaki; Koan, Yoko; Miyake, Hirohisa; Ono, Yuko; Moriki, Akihito; Mori, Koreaki; Mokudai, Toshihiko; Uchida, Yasufumi; Kumano, Osamu

    2005-09-01

    Five cases of traumatic subdural hematomas in the subacute stage (from 7 to 20 days after head injury) were treated in one male and four females, aged from 63 to 82 years, with evacuation via craniotomy in three and aspiration via burr hole surgery in two. All hematomas were evaluated by T1-, T2-, and diffusion-weighted magnetic resonance imaging, and measurement of the apparent diffusion coefficient (ADC). Diffusion-weighted imaging showed the hematoma as a crescent high intensity area with a low intensity rim close to the brain surface (two-layered structure) in four cases and as high intensity with low intensity components in one case. The high intensity areas under the dura mater on diffusion-weighted imaging appeared as homogeneous high intensity on T1- and T2-weighted imaging in four cases, and inhomogeneous high intensity on T1- and isointensity on T2-weighted imaging in one case. The mean ADC value of the high intensity areas was 0.58 +/- 0.23 (mean +/- standard deviation) x 10(-3) mm2/sec. The operative findings revealed the high intensity areas as solid clots. The low intensity areas on diffusion-weighted imaging appeared as homogeneous high intensity in four cases and inhomogeneous isointensity with high intensity components in one case on T1- and T2-weighted imaging. The mean ADC value of the low intensity areas was 2.03 +/- 0.27 x 10(-3) mm2/sec. The operative findings revealed the low intensity areas as mixtures of resolved clot and cerebrospinal fluid. Diffusion-weighted imaging showed the characteristic two-layered structure in traumatic subdural hematomas in the subacute stage, and analysis of the ADC values was useful for differentiating solid from liquid hematoma and for selection of the surgical procedure. PMID:16195646

  11. Diffusion-weighted magnetic resonance imaging of the normal canine brain.

    PubMed

    Hartmann, Antje; Söffler, Charlotte; Failing, Klaus; Schaubmar, Andreas; Kramer, Martin; Schmidt, Martin J

    2014-01-01

    Diffusion-weighted imaging (DWI) MRI has been primarily reported as a method for diagnosing cerebrovascular disease in veterinary patients. In humans, clinical applications for diffusion-weighted MRI have also included epilepsy, Alzheimer's, and Creutzfeld-Jakob disease. Before these applications can be developed in veterinary patients, more data on brain diffusion characteristics are needed. Therefore, the aim of this study was to evaluate the distribution of diffusion in the normal canine brain. Magnetic resonance imaging of the brain was performed in ten, clinically normal, purpose-bred beagle dogs. On apparent diffusion coefficient maps, regions of interest were drawn around the caudate nucleus, thalamus, piriform lobe, hippocampus, semioval center, and cerebral cortex. Statistically significant differences in mean apparent diffusion coefficient were found for the internal capsule, hippocampus, and thalamus. The highest apparent diffusion coefficient (1044.29 ± 165.21 μm(2)/s (mean ± SD (standard deviation)) was detected in the hippocampus. The lowest apparent diffusion coefficient was measured in the semioval center (721.39 ± 126.28 μm(2)/s (mean ± SD)). Significant differences in mean apparent diffusion coefficients of the caudate nucleus, thalamus, and piriform lobe were found by comparing right and left sides. Differences between brain regions may occur due to differences in myelination, neural density, or fiber orientation. The reason for the differences between right and left sides remains unclear. Data from the current study provide background for further studies of diffusion changes in dogs with brain disease. PMID:24798796

  12. Improved diffusion-weighting efficiency of pulsed gradient stimulated echo MR measurements with background gradient cross-term suppression.

    PubMed

    Finsterbusch, Jürgen

    2008-04-01

    Accurate diffusion measurements with pulsed gradient NMR are hampered by cross-terms of the diffusion-weighting and background gradients. For experiments based on a stimulated echo pulse sequence, that is preferred for samples with a T2 short compared to the diffusion time, a diffusion-weighting scheme has been presented that avoids these cross-terms in each of the en- and decoding periods separately. However, this approach suffers from a reduced diffusion-weighting efficiency because the two gradients applied in each of the periods have effectively opposite polarities leading to a partial cancellation. An extension of this scheme is presented that involves an additional gradient pulse in each period and delivers an improved diffusion-weighting efficiency without sacrificing the cross-term compensation. Analytical expressions for the gradient pulse lengths and amplitudes are given for arbitrary timing parameters. MR measurements with artificial (switched) background gradients were performed to test the cross-term compensation capability of the proposed extension. The results show that considerably higher q and b values can be achieved with the extension without changing the timing parameters. The MR measurements yielded identical diffusion coefficients without, with the same, and with different background gradients in the en- and decoding periods demonstrating the cross-term compensation of the presented approach. PMID:18226941

  13. Improved diffusion-weighting efficiency of pulsed gradient stimulated echo MR measurements with background gradient cross-term suppression

    NASA Astrophysics Data System (ADS)

    Finsterbusch, Jürgen

    2008-04-01

    Accurate diffusion measurements with pulsed gradient NMR are hampered by cross-terms of the diffusion-weighting and background gradients. For experiments based on a stimulated echo pulse sequence, that is preferred for samples with a T2 short compared to the diffusion time, a diffusion-weighting scheme has been presented that avoids these cross-terms in each of the en- and decoding periods separately. However, this approach suffers from a reduced diffusion-weighting efficiency because the two gradients applied in each of the periods have effectively opposite polarities leading to a partial cancellation. An extension of this scheme is presented that involves an additional gradient pulse in each period and delivers an improved diffusion-weighting efficiency without sacrificing the cross-term compensation. Analytical expressions for the gradient pulse lengths and amplitudes are given for arbitrary timing parameters. MR measurements with artificial (switched) background gradients were performed to test the cross-term compensation capability of the proposed extension. The results show that considerably higher q and b values can be achieved with the extension without changing the timing parameters. The MR measurements yielded identical diffusion coefficients without, with the same, and with different background gradients in the en- and decoding periods demonstrating the cross-term compensation of the presented approach.

  14. [Diffusion Weighted Magnetic Resonance Imaging and its Application in Ophthalmology].

    PubMed

    Lindner, T; Langner, S; Paul, K; Pohlmann, A; Hadlich, S; Niendorf, T; Jünemann, A; Guthoff, R F; Stachs, O

    2015-12-01

    The value of diffusion-weighted magnet resonance imaging (DWI-MRI) has been demonstrated for an ever growing range of clinical indications. DWI is sensitive to the diffusion of water molecules and probes their random displacement within tissue. DWI provides both qualitative and quantitative information on tissue characteristics, e.g. tissue cellularity. This review provides an overview of diffusion-weighted imaging and its emerging applications in ophthalmology. The basic physics and technical foundations of DWI are introduced. The emerging applications of DWI are surveyed, particularly in diseases of the eye, orbit and optical nerve. PMID:26678901

  15. Differentiation of Reactive and Tumor Metastatic Lymph Nodes with Diffusion-weighted and SPIO Enhanced MRI

    PubMed Central

    Zhang, Fan; Zhu, Lei; Huang, Xinglu; Niu, Gang; Chen, Siouan

    2012-01-01

    Objectives Determination of lymphatic metastasis is of great importance for both treatment planning and patient prognosis. We aim to distinguish tumor metastatic lymph nodes (TLNs) and reactive lymph nodes (RLNs) with diffusion-weighted and superparamagnetic iron oxide (SPIO) enhanced magnetic resonance imaging (MRI). Materials and methods Ipsilateral popliteal lymph node metastasis or lymphadenitis model was established by hock injection of either luciferase-expressing 4T1 murine breast cancer cells or Complete Freund Adjuvant (CFA) in male Balb/C mice. At different time points after inoculation, bioluminescence imaging, T2-weighted, diffusion-weighted and SPIO enhanced MRI were performed. Imaging findings were confirmed by histopathological staining. Results Size enlargement was observed in both TLNs and RLNs. At day 28, TLNs showed strong bioluminescence signal and bigger size than RLNs (p < 0.01). At early stages up to day 21, both TLNs and RLNs appeared homogeneous on diffusion-weighted imaging (DWI). At day 28, TLNs showed heterogeneous apparent diffusion coefficient (ADC) map with significantly higher average ADC value of 0.41 ± 0.03 × 10−3 mm2/s than that of RLNs (0.34 ± 0.02 10−3 mm2/s, p < 0.05). On SPIO enhanced MRI, both TLNs and RLNs showed distinct T2 signal reduction at day 21 after inoculation. At day 28, TLNs demonstrated partial uptake of the iron oxide particles, which was confirmed by Prussian blue staining. Conclusions Both diffusion-weighted and SPIO enhanced MRI can distinguish tumor metastatic lymph nodes from reactive lymph nodes. However, neither method is able to detect tumor metastasis to the draining lymph nodes at early stages. PMID:22588595

  16. Imaging hypothalamic activity using diffusion weighted magnetic resonance imaging in the mouse and human brain.

    PubMed

    Lizarbe, Blanca; Benítez, Ania; Sánchez-Montañés, Manuel; Lago-Fernández, Luis F; Garcia-Martin, María L; López-Larrubia, Pilar; Cerdán, Sebastián

    2013-01-01

    Hypothalamic appetite regulation is a vital homeostatic process underlying global energy balance in animals and humans, its disturbances resulting in feeding disorders with high morbidity and mortality. The objective evaluation of appetite remains difficult, very often restricted to indirect measurements of food intake and body weight. We report here, the direct, non-invasive visualization of hypothalamic activation by fasting using diffusion weighted magnetic resonance imaging, in the mouse brain as well as in a preliminary study in the human brain. The brain of fed or fasted mice or humans were imaged at 7 or 1.5 Tesla, respectively, by diffusion weighted magnetic resonance imaging using a complete range of b values (10diffusion weighted image data sets were registered and analyzed pixel by pixel using a biexponential model of diffusion, or a model-free Linear Discriminant Analysis approach. Biexponential fittings revealed statistically significant increases in the slow diffusion parameters of the model, consistent with a neurocellular swelling response in the fasted hypothalamus. Increased resolution approaches allowed the detection of increases in the diffusion parameters within the Arcuate Nucleus, Ventromedial Nucleus and Dorsomedial Nucleus. Independently, Linear Discriminant Analysis was able to classify successfully the diffusion data sets from mice and humans between fed and fasted states. Present results are consistent with increased glutamatergic neurotransmission during orexigenic firing, a process resulting in increased ionic accumulation and concomitant osmotic neurocellular swelling. This swelling response is spatially extendable through surrounding astrocytic networks until it becomes MRI detectable. Present findings open new avenues for the direct, non-invasive, evaluation of appetite disorders and other hypothalamic pathologies helping potentially in the development of the corresponding therapies. PMID:23000787

  17. Diffusion-weighted magnetic resonance imaging findings in a patient with struma ovarii.

    PubMed

    Takeshita, Tohru; Ninoi, Teruhisa; Maebayashi, Tetunori; Doh, Kunihiko; Hashimoto, Shigeo; Mniki, Yumo

    2014-06-01

    In this report, the magnetic resonance imaging (MRI) appearance of struma ovarii (SO) in a patient who underwent diffusion-weighted imaging (DWI) of the pelvis and subsequent histological analysis is described. The solid portion of SO showed a high apparent diffusion coefficient (ADC) value, indicating unrestricted diffusion, and each loculus of SO showed different ADC values due to the different viscosity of the cyst contents in each loculus. These unique and characteristic DWI findings may serve as a helpful sign in making the correct diagnosis of SO when DWI findings are interpreted in conjunction with conventional MRI findings. PMID:25272567

  18. Evaluation of Hepatic Tumors Using Intravoxel Incoherent Motion Diffusion-Weighted MRI

    PubMed Central

    Wang, Mingjie; Li, Xudan; Zou, Jianxun; Chen, Xugao; Chen, Shuyan; Xiang, Wanqing

    2016-01-01

    Background This study aimed to evaluate the diagnostic value of the D value, D* value, and f magnitude for identifying benign and malignant hepatic tumors using intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI). Material/Methods Data of 89 cases (123 lesions) with hepatic tumor confirmed by surgical pathology and postoperative follow-up were retrospectively collected. Among these cases, 40 cases were benign hepatic tumors (57 lesions) and 49 cases were malignant hepatic tumors (66 lesions). All subjects underwent conventional MRI with T1WI, T2WI, multi-b-value DWI, and dynamic enhanced LAVA scan. Diffusion-weighted images with 11 b values (0, 10, 20, 30, 50, 80, 100, 200, 400, 800, and 1000 s/mm2) were obtained to calculate true molecular diffusion (D), perfusion-related diffusion coefficient (D*), and perfusion fraction (f). The diagnostic performance in differentiating between malignant and benign hepatic lesions was analyzed. Results Malignant lesions had a significantly lower D value ([1.04±0.34]×10−3 mm2/s) and D* value ([16.5±7.7]×10−3 mm2/s) compared to benign lesions (D value: [1.70±0.55]×10−3 mm2/s, P<0.01; D* value: [21.7±9.9]×10−3 mm2/s, P<0.01). There was no statistically significant difference in f values between malignant (23.3±9.5) and benign lesions (33.5±14.9, P=0.13). In addition, D exhibited a better diagnostic performance than D* in terms of the area under the curve, sensitivity, and specificity when identifying malignancies from benign lesions. Conclusions D and D* are significant parameters for diagnosing hepatic tumors. Moreover, the D value is a more reliable parameter in distinguishing benign and malignant hepatic tumors. PMID:26931063

  19. Single-Shot Echo-Planar Diffusion-Weighted MR Imaging at 3T and 1.5T for Differentiation of Benign Vertebral Fracture Edema and Tumor Infiltration

    PubMed Central

    Park, Hee Jin; Rho, Myung Ho; Chung, Eun Chul; Kim, Mi Sung; Kwon, Heon Ju; Youn, In Young

    2016-01-01

    Objective To compare the apparent diffusion coefficient (ADC) value using single-shot echo-planar imaging sequences at 3T and 1.5T for differentiation of benign fracture edema and tumor infiltration of the vertebral body. Materials and Methods A total of 46 spinal examinations were included in the 1.5T MRI group, and a total of 40 spinal examinations were included in the 3T MRI group. The ADC values of the lesion were measured and calculated. The diagnostic performance of the conventional MR image containing sagittal T2-weighted fat saturated image and each diffusion weighted image (DWI) with an ADC value with different b values were evaluated. Results The mean ADC value of the benign lesions was higher than that of the malignant lesions on 1.5T and 3T (p < 0.05). The sensitivity of the diagnostic performance was higher with an additional DWI in both 1.5T and 3T, but the sensitivities were similar with the addition of b values of 400 and 1000. The specificities of the diagnostic performances did not show significant differences (p value > 0.05). The diagnostic accuracies were higher when either of the DWIs (b values of 400 and 1000) was added to routine MR image for 1.5T and 3T. Statistical differences between 1.5T and 3T or between b values of 400 and 1000 were not seen. Conclusion The ADC values of the benign lesions were significantly higher than those of the malignant lesions on 1.5T and 3T. There was no statistically significant difference in the diagnostic performances when either of the DWIs (b values of 400 and 1000) was added to the routine MR image for 1.5T and 3T. PMID:27587948

  20. WE-G-BRD-01: Diffusion Weighted MRI for Response Assessment of Inoperable Lung Tumors for Patients Undergoing SBRT Treatment

    SciTech Connect

    Tyagi, N; Wengler, K; Yorke, E; Hunt, M; Deasy, J; Rimner, A

    2014-06-15

    Purpose: To investigate early changes in tumor Apparent Diffusion Coefficients derived from diffusion weighted (DW)-MRI of lung cancer patients undergoing SBRT, as a possible early predictor of treatment response. Methods: DW-MRI scans were performed in this prospective phase I IRB-approved study of inoperable lung tumors at various time-points during the course of SBRT treatments. Axial DW scan using multi b-values ranging from 0–1000 s/mm{sup 2} were acquired in treatment position on a 3T Philips MR scanner during simulation, one hour after the first fraction (8 Gy), after a total of 5 fractions (40 Gy) and 4 weeks after SBRT delivery. A monoexponential model based on a least square fit from all b values was performed on a pixel-by-pixel basis and ADC was calculated. GTVs drawn on 4DCT for planning were mapped on the T2w MRI (acquired at exhale) after deformable registration. These volumes were then mapped on DWI scan for ADC calculation after rigid registration between the anatomical scan and diffusion scan. T2w scan on followup time points were deformably registered to the pretreatment T2 scan. Results: The first two patients in this study were analyzed. Median ADC values were 1.48, 1.48, 1.62 and 1.83 (10{sup −3}×) mm{sup 2}/s at pretreatment, after 8 Gy, after 40 Gy and 4 weeks posttreatment for the first patient and 1.57, 1.53, 1.66 and 1.72 (10{sup −3}×) mm{sup 2}/s for the second patient. ADC increased more significantly after 4 weeks of treatment rather than immediately post treatment, implying that late ADC value may be a better predictor of tumor response for SBRT treatment. The fraction of tumor pixels at high ADC values increased at 4 weeks post treatment. Conclusion: The observed increase in ADC values before the end of radiotherapy may be a surrogate for tumor response, but further patient accrual will be necessary to determine its value.

  1. Pyogenic and non-pyogenic spinal infections: emphasis on diffusion-weighted imaging for the detection of abscesses and pus collections.

    PubMed

    Moritani, T; Kim, J; Capizzano, A A; Kirby, P; Kademian, J; Sato, Y

    2014-09-01

    The incidence of spinal infections has increased in the past two decades, owing to the increasing number of elderly patients, immunocompromised conditions, spinal surgery and instrumentation, vascular access and intravenous drug use. Conventional MRI is the gold standard for diagnostic imaging; however, there are still a significant number of misdiagnosed cases. Diffusion-weighted imaging (DWI) with a b-value of 1000 and apparent diffusion coefficient (ADC) maps provide early and accurate detection of abscess and pus collection. Pyogenic infections are classified into four types of extension based on MRI and DWI findings: (1) epidural/paraspinal abscess with spondylodiscitis, (2) epidural/paraspinal abscess with facet joint infection, (3) epidural/paraspinal abscess without concomitant spondylodiscitis or facet joint infection and (4) intradural abscess (subdural abscess, purulent meningitis and spinal cord abscess). DWI easily detects abscesses and demonstrates the extension, multiplicity and remote disseminated infection. DWI is often a key image in the differential diagnosis. Important differential diagnoses include epidural, subdural or subarachnoid haemorrhage, cerebrospinal fluid leak, disc herniation, synovial cyst, granulation tissue, intra- or extradural tumour and post-surgical fluid collections. DWI and the ADC values are affected by susceptibility artefacts, incomplete fat suppression and volume-averaging artefacts. Recognition of artefacts is essential when interpreting DWI of spinal and paraspinal infections. DWI is not only useful for the diagnosis but also for the treatment planning of pyogenic and non-pyogenic spinal infections. PMID:24999081

  2. Pyogenic and non-pyogenic spinal infections: emphasis on diffusion-weighted imaging for the detection of abscesses and pus collections

    PubMed Central

    Kim, J; Capizzano, A A; Kirby, P; Kademian, J; Sato, Y

    2014-01-01

    The incidence of spinal infections has increased in the past two decades, owing to the increasing number of elderly patients, immunocompromised conditions, spinal surgery and instrumentation, vascular access and intravenous drug use. Conventional MRI is the gold standard for diagnostic imaging; however, there are still a significant number of misdiagnosed cases. Diffusion-weighted imaging (DWI) with a b-value of 1000 and apparent diffusion coefficient (ADC) maps provide early and accurate detection of abscess and pus collection. Pyogenic infections are classified into four types of extension based on MRI and DWI findings: (1) epidural/paraspinal abscess with spondylodiscitis, (2) epidural/paraspinal abscess with facet joint infection, (3) epidural/paraspinal abscess without concomitant spondylodiscitis or facet joint infection and (4) intradural abscess (subdural abscess, purulent meningitis and spinal cord abscess). DWI easily detects abscesses and demonstrates the extension, multiplicity and remote disseminated infection. DWI is often a key image in the differential diagnosis. Important differential diagnoses include epidural, subdural or subarachnoid haemorrhage, cerebrospinal fluid leak, disc herniation, synovial cyst, granulation tissue, intra- or extradural tumour and post-surgical fluid collections. DWI and the ADC values are affected by susceptibility artefacts, incomplete fat suppression and volume-averaging artefacts. Recognition of artefacts is essential when interpreting DWI of spinal and paraspinal infections. DWI is not only useful for the diagnosis but also for the treatment planning of pyogenic and non-pyogenic spinal infections. PMID:24999081

  3. Diffusion-Weighted MRI for the Assessment of Liver Fibrosis: Principles and Applications

    PubMed Central

    Attinà, Giancarlo; Fuccio Sanzà, Giovanni; Foti, Pietro Valerio; Ettorre, Giovanni Carlo; Milone, Pietro

    2015-01-01

    The importance of an early identification of hepatic fibrosis has been emphasized, in order to start therapy and obtain fibrosis regression. Biopsy is the gold-standard method for the assessment of liver fibrosis in chronic liver diseases, but it is limited by complications, interobserver variability, and sampling errors. Several noninvasive methods have been recently introduced into clinical routine, in order to detect liver fibrosis early. One of the most diffuse approaches is represented by diffusion-weighted liver MRI. In this review, the main technical principles are briefly reported in order to explain the rationale for clinical applications. In addition, roles of apparent diffusion coefficient, intravoxel incoherent motion, and relative apparent diffusion coefficient are also reported, showing their advantages and limits. PMID:25866819

  4. Whole body MRI: Improved Lesion Detection and Characterization With Diffusion Weighted Techniques

    PubMed Central

    Attariwala, Rajpaul; Picker, Wayne

    2013-01-01

    Diffusion-weighted imaging (DWI) is an established functional imaging technique that interrogates the delicate balance of water movement at the cellular level. Technological advances enable this technique to be applied to whole-body MRI. Theory, b-value selection, common artifacts and target to background for optimized viewing will be reviewed for applications in the neck, chest, abdomen, and pelvis. Whole-body imaging with DWI allows novel applications of MRI to aid in evaluation of conditions such as multiple myeloma, lymphoma, and skeletal metastases, while the quantitative nature of this technique permits evaluation of response to therapy. Persisting signal at high b-values from restricted hypercellular tissue and viscous fluid also permits applications of DWI beyond oncologic imaging. DWI, when used in conjunction with routine imaging, can assist in detecting hemorrhagic degradation products, infection/abscess, and inflammation in colitis, while aiding with discrimination of free fluid and empyema, while limiting the need for intravenous contrast. DWI in conjunction with routine anatomic images provides a platform to improve lesion detection and characterization with findings rivaling other combined anatomic and functional imaging techniques, with the added benefit of no ionizing radiation. PMID:23960006

  5. WE-G-18C-09: Separating Perfusion and Diffusion Components From Diffusion Weighted MRI of Rectum Tumors Based On Intravoxel Incoherent Motion (IVIM) Analysis

    SciTech Connect

    Tyagi, N; Wengler, K; Mazaheri, Y; Hunt, M; Deasy, J; Gollub, M

    2014-06-15

    Purpose: Pseudodiffusion arises from the microcirculation of blood in the randomly oriented capillary network and contributes to the signal decay acquired using a multi-b value diffusion weighted (DW)-MRI sequence. This effect is more significant at low b-values and should be properly accounted for in apparent diffusion coefficient (ADC) calculations. The purpose of this study was to separate perfusion and diffusion component based on a biexponential and a segmented monoexponential model using IVIM analysis Methods. The signal attenuation is modeled as S(b) = S0[(1−f)exp(−bD) + fexp(−bD*)]. Fitting the biexponetial decay leads to the quantification of D, the true diffusion coefficient, D*, the pseudodiffusion coefficient, and f, the perfusion fraction. A nonlinear least squares fit and two segmented monoexponential models were used to derive the values for D, D*,‘and f. In the segmented approach b = 200 s/mm{sup 2} was used as the cut-off value for calculation of D. DW-MRI's of a rectum cancer patient were acquired before chemotherapy, before radiation therapy (RT), and 4 weeks into RT and were investigated as an example case. Results: Mean ADC for the tumor drawn on the DWI cases was 0.93, 1.0 and 1.13 10{sup −3}×mm{sup 2}/s before chemotherapy, before RT and 4 weeks into RT. The mean (D.10{sup −3} × mm{sup 2}/s, D* 10{sup −3} × mm{sup 2}/s, and f %) based on biexponential fit was (0.67, 18.6, and 27.2%), (0.72, 17.7, and 28.9%) and (0.83,15.1, and 30.7%) at these time points. The mean (D, D* f) based on segmented fit was (0.72, 10.5, and 12.1%), (0.72, 8.2, and 17.4%) and (.82, 8.1, 16.5%) Conclusion: ADC values are typically higher than true diffusion coefficients. For tumors with significant perfusion effect, ADC should be analyzed at higher b-values or separated from the perfusion component. Biexponential fit overestimates the perfusion fraction because of increased sensitivity to noise at low b-values.

  6. Diffusion Weighted Magnetic Resonance Imaging for the Characterization of Solitary Pulmonary Lesions

    PubMed Central

    Çakır, Çağlayan; Gençhellaç, Hakan; Temizöz, Osman; Polat, Ahmet; Şengül, Ersin; Duygulu, Gökhan

    2015-01-01

    Background: We evaluated the differential diagnosis of solitary pulmonary lesions on magnetic resonance imaging. Aims: To investigate the value of diffusion weighted imaging on the differential diagnosis of solitary pulmonary lesions. Study Design: Randomized prospective study. Methods: This prospective study included 48 solitary pulmonary nodules and masses (18 benign, 30 malignant). Single shot echo planar spin echo diffusion weighted imaging (DWI) was performed with two b factors (0 and 1000 s/mm2). Apparent diffusion coefficients (ADCs) were calculated. On diffusion weighted (DW) trace images, the signal intensities (SI) of the lesions were visually compared to the SI of the thoracic spinal cord using a 5-point scale: 1: hypointense, 2: moderately hypointense, 3: isointense, 4: moderately hyperintense, 5: significantly hyperintense. For the quantitative evaluation, the lesion to thoracic spinal signal intensity ratios and the ADCs of the lesions were compared between groups. Results: On visual evaluation, taking the density of the spinal cord as a reference, most benign lesions were found to be hypointense, while most of the malignant lesions were evaluated as hyperintense on DWI with a b factor of 1000 s/mm2. In contrast, on T2 weighted images, it was seen that the distinction of malignant lesions from benign lesions was not statistically significant. The ADCs of the malignant lesions were significantly lower than those of benign lesions (mean ADC was 2.02×10−3 mm2/s for malignant lesions, and 1.195×10−3±0.3 mm2/s for benign lesions). Setting the cut-off value at 1.5×10−3, ADC had a sensitivity of 86.7% and a specificity of 88.9% for the differentiation of benign lesions from malignant lesions. Conclusion: DWI may aid in the differential diagnosis of solitary pulmonary lesions. (ClinicalTrials.gov Identifier: NCT02482181) PMID:26740901

  7. Spatially constrained incoherent motion method improves diffusion-weighted MRI signal decay analysis in the liver and spleen

    PubMed Central

    Taimouri, Vahid; Afacan, Onur; Perez-Rossello, Jeannette M.; Callahan, Michael J.; Mulkern, Robert V.; Warfield, Simon K.; Freiman, Moti

    2015-01-01

    Purpose: To evaluate the effect of the spatially constrained incoherent motion (SCIM) method on improving the precision and robustness of fast and slow diffusion parameter estimates from diffusion-weighted MRI in liver and spleen in comparison to the independent voxel-wise intravoxel incoherent motion (IVIM) model. Methods: We collected diffusion-weighted MRI (DW-MRI) data of 29 subjects (5 healthy subjects and 24 patients with Crohn’s disease in the ileum). We evaluated parameters estimates’ robustness against different combinations of b-values (i.e., 4 b-values and 7 b-values) by comparing the variance of the estimates obtained with the SCIM and the independent voxel-wise IVIM model. We also evaluated the improvement in the precision of parameter estimates by comparing the coefficient of variation (CV) of the SCIM parameter estimates to that of the IVIM. Results: The SCIM method was more robust compared to IVIM (up to 70% in liver and spleen) for different combinations of b-values. Also, the CV values of the parameter estimations using the SCIM method were significantly lower compared to repeated acquisition and signal averaging estimated using IVIM, especially for the fast diffusion parameter in liver (CVIV IM = 46.61 ± 11.22, CVSCIM = 16.85 ± 2.160, p < 0.001) and spleen (CVIV IM = 95.15 ± 19.82, CVSCIM = 52.55 ± 1.91, p < 0.001). Conclusions: The SCIM method characterizes fast and slow diffusion more precisely compared to the independent voxel-wise IVIM model fitting in the liver and spleen. PMID:25832079

  8. Diffusion-Weighted Magnetic Resonance Imaging to Evaluate Major Salivary Gland Function Before and After Radiotherapy

    SciTech Connect

    Dirix, Piet Keyzer, Frederik de; Vandecaveye, Vincent; Stroobants, Sigrid; Hermans, Robert; Nuyts, Sandra

    2008-08-01

    Purpose: To evaluate diffusion-weighted (DW)-MRI as a noninvasive tool to investigate major salivary gland function before and after radiotherapy (RT) for head and neck cancer (HNC). Methods and Materials: DW-MRI was performed in 8 HNC patients before and after parotid-sparing RT (mean dose to the contralateral parotid gland <26 Gy). A DW sequence was performed once at rest and then repeated continuously during salivary stimulation. Apparent diffusion coefficient (ADC) maps for both parotid and submandibular glands were calculated. Findings were compared with salivary gland scintigraphy. Results: Before RT, the mean ADC value at rest was significantly lower in the parotid than in the submandibular glands. During the first 5 min of stimulation, the ADC value of the salivary glands showed a decrease, followed by a steady increase until a peak ADC, significantly higher than the baseline value, was reached after a median of 17 min. The baseline ADC value at rest was significantly higher after RT than before RT in the nonspared salivary glands but not in the spared parotid glands. In the contralateral parotid glands, the same response was seen as before RT. This pattern was completely lost in the nonspared glands. These results corresponded with remaining or loss of salivary function, respectively, as confirmed by salivary gland scintigraphy. Conclusions: Diffusion-weighted-MRI allows noninvasive evaluation of functional changes in the major salivary glands after RT and is a promising tool for investigating radiation-induced xerostomia.

  9. Limitations and Prospects for Diffusion-Weighted MRI of the Prostate

    PubMed Central

    Bourne, Roger; Panagiotaki, Eleftheria

    2016-01-01

    Diffusion-weighted imaging (DWI) is the most effective component of the modern multi-parametric magnetic resonance imaging (mpMRI) scan for prostate pathology. DWI provides the strongest prediction of cancer volume, and the apparent diffusion coefficient (ADC) correlates moderately with Gleason grade. Notwithstanding the demonstrated cancer assessment value of DWI, the standard measurement and signal analysis methods are based on a model of water diffusion dynamics that is well known to be invalid in human tissue. This review describes the biophysical limitations of the DWI component of the current standard mpMRI protocol and the potential for significantly improved cancer assessment performance based on more sophisticated measurement and signal modeling techniques. PMID:27240408

  10. Limitations and Prospects for Diffusion-Weighted MRI of the Prostate.

    PubMed

    Bourne, Roger; Panagiotaki, Eleftheria

    2016-01-01

    Diffusion-weighted imaging (DWI) is the most effective component of the modern multi-parametric magnetic resonance imaging (mpMRI) scan for prostate pathology. DWI provides the strongest prediction of cancer volume, and the apparent diffusion coefficient (ADC) correlates moderately with Gleason grade. Notwithstanding the demonstrated cancer assessment value of DWI, the standard measurement and signal analysis methods are based on a model of water diffusion dynamics that is well known to be invalid in human tissue. This review describes the biophysical limitations of the DWI component of the current standard mpMRI protocol and the potential for significantly improved cancer assessment performance based on more sophisticated measurement and signal modeling techniques. PMID:27240408

  11. Diffusion-weighted and diffusion-tensor imaging of normal and diseased uterus

    PubMed Central

    Kara Bozkurt, Duygu; Bozkurt, Murat; Nazli, Mehmet Ali; Mutlu, Ilhan Nahit; Kilickesmez, Ozgur

    2015-01-01

    Owing to technical advances and improvement of the software, diffusion weighted imaging and diffusion tensor imaging (DWI and DTI) greatly improved the diagnostic value of magnetic resonance imaging (MRI) of the pelvic region. These imaging sequences can exhibit important tissue contrast on the basis of random diffusion (Brownian motion) of water molecules in tissues. Quantitative measurements can be done with DWI and DTI by apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values respectively. ADC and FA values may be changed by various physiological and pathological conditions providing additional information to conventional MRI. The quantitative DWI assists significantly in the differentiation of benign and malignant lesions. It can demonstrate the microstructural architecture and celluler density of the normal and diseased uterine zones. On the other hand, DWI and DTI are useful for monitoring the treatment outcome of the uterine lesions. In this review, we discussed advantages of DWI and DTI of the normal and diseased uterus. PMID:26217454

  12. Abdominal applications of diffusion-weighted magnetic resonance imaging: Where do we stand

    PubMed Central

    Morani, Ajaykumar C; Elsayes, Khaled M; Liu, Peter S; Weadock, William J; Szklaruk, Janio; Dillman, Jonathan Russell; Khan, Asra; Chenevert, Thomas L; Hussain, Hero K

    2013-01-01

    Diffusion-weighted imaging (DWI) is one of the magnetic resonance imaging (MRI) sequences providing qualitative as well as quantitative information at a cellular level. It has been widely used for various applications in the central nervous system. Over the past decade, various extracranial applications of DWI have been increasingly explored, as it may detect changes even before signal alterations or morphological abnormalities become apparent on other pulse sequences. Initial results from abdominal MRI applications are promising, particularly in oncological settings and for the detection of abscesses. The purpose of this article is to describe the clinically relevant basic concepts of DWI, techniques to perform abdominal DWI, its analysis and applications in abdominal visceral MR imaging, in addition to a brief overview of whole body DWI MRI. PMID:23671743

  13. Diffusion-weighted MR imaging in gynecologic cancers.

    PubMed

    Motoshima, Shigenobu; Irie, Hiroyuki; Nakazono, Takahiko; Kamura, Toshiharu; Kudo, Sho

    2011-12-01

    Diffusion-weighted imaging (DWI) reflects changes in proton mobility caused by pathological alterations of tissue cellularity, cellular membrane integrity, extracellular space perfusion, and fluid viscosity. Functional imaging is becoming increasingly important in the evaluation of cancer patients because of the limitations of morphologic imaging. DWI is being applied to the detection and characterization of tumors and the evaluation of treatment response in patients with cancer. The advantages of DWI include its cost-effectiveness and brevity of execution, its complete noninvasiveness, its lack of ionizing radiation, and the fact that it does not require injection of contrast material, thus enabling its use in patients with renal dysfunction. In this article, we describe the clinical application of DWI to gynecological disorders and its diagnostic efficacy therein. PMID:22247805

  14. Super-resolution in diffusion-weighted imaging.

    PubMed

    Scherrer, Benoit; Gholipour, Ali; Warfield, Simon K

    2011-01-01

    Diffusion-weighted imaging (DWI) enables non-invasive investigation and characterization of the white-matter but suffers from a relatively poor resolution. In this work we propose a super-resolution reconstruction (SRR) technique based on the acquisition of multiple anisotropic orthogonal DWI scans. We address the problem of patient motions by aligning the volumes both in space and in q-space. The SRR is formulated as a maximum a posteriori (MAP) problem. It relies on a volume acquisition model which describes the generation of the acquired scans from the unknown high-resolution image. It enables the introduction of image priors that exploit spatial homogeneity and enables regularized solutions. We detail our resulting SRR optimization procedure and report various experiments including numerical simulations, synthetic SRR scenario and real world SRR scenario. Super-resolution reconstruction in DWI may enable DWI to be performed with unprecedented resolution. PMID:21995021

  15. Diffusion-weighted MRI for the detection of colorectal polyps: feasibility study.

    PubMed

    Leufkens, Anke M; Kwee, Thomas C; van den Bosch, Maurice A A J; Mali, Willem P Th M; Takahara, Taro; Siersema, Peter D

    2013-01-01

    The purpose of this study was to determine the feasibility of diffusion-weighted magnetic resonance imaging (DWI) for detecting colorectal polyps. DWI (high b-value of 1000 s/mm(2)) was prospectively performed in 26 symptomatic patients who were scheduled to undergo colonoscopy. DWI and colonoscopic findings were interpreted in a blinded manner. The sensitivity and positive predictive value (PPV) of DWI for the detection of clinically relevant polyps (≥6 mm) and colorectal cancer (CRC) were calculated on a per-lesion basis, using colonoscopy results as the standard of reference. Sensitivity, specificity, PPV and negative predictive value (NPV) on a per-patient basis were also calculated. Sensitivity and PPV on a per-lesion basis were 80.0% [95% confidence interval (CI): 49.0%-94.3%] and 72.7% (95% CI: 43.4%-90.3%) for polyps ≥6 mm and CRC. Sensitivity, specificity, PPV and NPV on a per-patient basis were 85.7% (95% CI: 48.7%-97.4%), 84.2% (95% CI: 62.4%-94.5%), 66.7% (95% CI: 35.4%-87.9%) and 94.1% (95% CI: 73.0%-99.0%) for polyps ≥6mm and CRC. In conclusion, DWI cannot yet be recommended in a clinical setting in which DWI is performed first and subsequent colonoscopy is only performed in patients with positive findings at DWI. Further (technical) developments are required to increase its diagnostic yield. PMID:22898697

  16. Diffusional anisotropy of the human brain assessed with diffusion-weighted MR: Relation with normal brain development and aging

    SciTech Connect

    Nomura, Toshiyuki; Sakuma, Hajime; Takeda, Kan; Tagami, Tomoyasu; Okuda, Yasuyuki; Nakagawa, Tsuyoshi )

    1994-02-01

    To analyze diffusional anisotropy in frontal and occipital white matter of human brain quantitatively as a function of age by using diffusion-weighted MR imaging. Ten neonates (<1 month), 13 infants (1-10 months), 9 children (1-11 years), and 16 adults (20-79 years) were examined. After taking axial spin-echo images of the brain, diffusion-sensitive gradients were added parallel or perpendicular to the orientation of nerve fibers. The apparent diffusion coefficient parallel to the nerve fibers (0) and that perpendicular to the fibers (90) were computed. The anisotropic ratio (90/0) was calculated as a function of age. Anisotropic ratios of frontal white matter were significantly larger in neonates as compared with infants, children, or adults. The ratios showed rapid decrease until 6 months and thereafter were identical in all subjects. In the occipital lobe, the ratios were also greater in neonates, but the differences from other age groups were not so prominent as in the frontal lobe. Comparing anisotropic ratios between frontal and occipital lobes, a significant difference was observed only in neonates. Diffusion-weighted images demonstrated that the myelination process starts earlier in the occipital lobe than in the frontal lobe. The changes of diffusional anisotropy in white matter are completed within 6 months after birth. Diffusion-weighted imaging provides earlier detection of brain myelination compared with the conventional T1- and T2-weighted images. 18 refs., 6 figs., 1 tab.

  17. Whole-Body Diffusion-Weighted Imaging in Chronic Recurrent Multifocal Osteomyelitis in Children

    PubMed Central

    Leclair, Nadine; Thörmer, Gregor; Sorge, Ina; Ritter, Lutz; Schuster, Volker; Hirsch, Franz Wolfgang

    2016-01-01

    Objective Chronic recurrent multifocal osteomyelitis/ chronic non-bacterial osteomyelitis (CRMO/ CNO) is a rare auto-inflammatory disease and typically manifests in terms of musculoskeletal pain. Because of a high frequency of musculoskeletal disorders in children/ adolescents, it can be quite challenging to distinguish CRMO/ CNO from nonspecific musculosketetal pain or from malignancies. The purpose of this study was to evaluate the visibility of CRMO lesions in a whole-body diffusion-weighted imaging (WB-DWI) technique and its potential clinical value to better characterize MR-visible lesions. Material and Methods Whole-body imaging at 3T was performed in 16 patients (average: 13 years) with confirmed CRMO. The protocol included 2D Short Tau Inversion Recovery (STIR) imaging in coronal and axial orientation as well as diffusion-weighted imaging in axial orientation. Visibility of lesions in DWI and STIR was evaluated by two readers in consensus. The apparent diffusion coefficient (ADC) was measured for every lesion and corresponding reference locations. Results A total of 33 lesions (on average 2 per patient) visible in STIR and DWI images (b = 800 s/mm2 and ADC maps) were included, predominantly located in the long bones. With a mean value of 1283 mm2/s in lesions, the ADC was significantly higher than in corresponding reference regions (782 mm2/s). By calculating the ratio (lesion to reference), 82% of all lesions showed a relative signal increase of 10% or higher and 76% (25 lesions) showed a signal increase of more than 15%. The median relative signal increase was 69%. Conclusion This study shows that WB-DWI can be reliably performed in children at 3T and predominantly, the ADC values were substantially elevated in CRMO lesions. WB-DWI in conjunction with clinical data is seen as a promising technique to distinguish benign inflammatory processes (in terms of increased ADC values) from particular malignancies. PMID:26799970

  18. Diffusion-weighted magnetic resonance imaging in predicting the radiosensitivity of cervical cancer

    PubMed Central

    Ni, Xiaolei; Tong, Yuanhe; Xiao, Youping; Liao, Jiang; Chen, Yunbing; Wang, Min

    2015-01-01

    This study investigates the application value of diffusion-weighted magnetic resonance imaging in predicting cervical cancer radiosensitivity. Twenty-five patients who were newly diagnosed as cervical cancer and accepted simple radiotherapy were included in this study. Before external irradiation, 20 GY and at the end of irradiation, routine 1.5 T MRI and diffusion-weighted magnetic resonance imaging scanning were carried. Apparent diffusion coefficient (ADC) value of primary tumor was measured. Its correlation with tumor regression rate was analyzed. ADC values of before irradiation, 20 GY and at the end of irradiation was (0.93 ± 0.14) × 10-3 mm2/s, (1.25 ± 0.17) × 10-3 mm2/s and (1.55 ± 0.13) × 10-3 mm2/s, respectively. There were statistical significant differences (P< 0.01). D-value of ADC values between before and 20 GY external irradiation was (0.33 ± 0.16) mm2/s. The tumor volume before and at the end of external irradiation were (37.48 ± 26.83) cm3 and (4.41 ± 3.72) cm3 respectively, with tumor regression rate of before and after external irradiation of (0.86 ± 0.11). ADC values of before irradiation, 20 GY and at the end of irradiation did not correlate with tumor regression rate. D-value of ADC values between before and 20 GY external irradiation positively correlated with tumor regression rate (r = 0.423, P = 0.035). ADC value of cervical cancer increased after radiotherapy and early changes of ADC value was positively correlated with tumor regression rate, thus, ADC value could be used as a potential prediction factor for cervical cancer radiosensitivity. PMID:26550334

  19. Diffusion weighted magnetic resonance imaging and its recent trend—a survey

    PubMed Central

    Chilla, Geetha Soujanya; Tan, Cher Heng

    2015-01-01

    Since its inception in 1985, diffusion weighted magnetic resonance imaging has been evolving and is becoming instrumental in diagnosis and investigation of tissue functions in various organs including brain, cartilage, and liver. Even though brain related pathology and/or investigation remains as the main application, diffusion weighted magnetic resonance imaging (DWI) is becoming a standard in oncology and in several other applications. This review article provides a brief introduction of diffusion weighted magnetic resonance imaging, challenges involved and recent advancements. PMID:26029644

  20. Diffusion-Weighted Magnetic Resonance Imaging Early After Chemoradiotherapy to Monitor Treatment Response in Head-and-Neck Squamous Cell Carcinoma

    SciTech Connect

    Vandecaveye, Vincent; Dirix, Piet; De Keyzer, Frederik; Op de Beeck, Katya; Vander Poorten, Vincent; Hauben, Esther; Lambrecht, Maarten; Nuyts, Sandra; Hermans, Robert

    2012-03-01

    Purpose: To evaluate diffusion-weighted imaging (DWI) for assessment of treatment response in head and neck squamous cell carcinoma (HNSCC) three weeks after the end of chemoradiotherapy (CRT). Methods and Materials: Twenty-nine patients with HNSCC underwent magnetic resonance imaging (MRI) prior to and 3 weeks after CRT, including T{sub 2}-weighted and pre- and postcontrast T{sub 1}-weighted sequences and an echo-planar DWI sequence with six b values (0 to 1,000 s/mm{sup 2}), from which the apparent diffusion coefficient (ADC) was calculated. ADC changes 3 weeks posttreatment compared to baseline ( Increment ADC) between responding and nonresponding primary lesions and adenopathies were correlated with 2 years locoregional control and compared with a Mann-Whitney test. In a blinded manner, the Increment ADC was compared to conventional MRI 3 weeks post-CRT and the routinely implemented CT, on average 3 months post-CRT, which used size-related and morphological criteria. Positive and negative predictive values (PPV and NPV, respectively) were compared between the Increment ADC and anatomical imaging. Results: The Increment ADC of lesions with later tumor recurrence was significantly lower than lesions with complete remission for both primary lesions (-2.3% {+-} 0.3% vs. 80% {+-} 41%; p < 0.0001) and adenopathies (19.9% {+-} 32% vs. 63% {+-} 36%; p = 0.003). The Increment ADC showed a PPV of 89% and an NPV of 100% for primary lesions and a PPV of 70% and an NPV of 96% for adenopathies per neck side. DWI improved PPV and NPV compared to anatomical imaging. Conclusion: DWI with the Increment ADC 3 weeks after concluding CRT for HNSCC allows for early assessment of treatment response.

  1. Intravoxel Incoherent Motion MR Imaging in the Head and Neck: Correlation with Dynamic Contrast-Enhanced MR Imaging and Diffusion-Weighted Imaging

    PubMed Central

    Xu, Xiao Quan; Choi, Young Jun; Sung, Yu Sub; Yoon, Ra Gyoung; Jang, Seung Won; Park, Ji Eun; Heo, Young Jin; Baek, Jung Hwan

    2016-01-01

    Objective To investigate the correlation between perfusion- and diffusion-related parameters from intravoxel incoherent motion (IVIM) and those from dynamic contrast-enhanced MR imaging (DCE-MRI) and diffusion-weighted imaging in tumors and normal muscles of the head and neck. Materials and Methods We retrospectively enrolled 20 consecutive patients with head and neck tumors with MR imaging performed using a 3T MR scanner. Tissue diffusivity (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) were derived from bi-exponential fitting of IVIM data obtained with 14 different b-values in three orthogonal directions. We investigated the correlation between D, f, and D* and model-free parameters from the DCE-MRI (wash-in, Tmax, Emax, initial AUC60, whole AUC) and the apparent diffusion coefficient (ADC) value in the tumor and normal masseter muscle using a whole volume-of-interest approach. Pearson's correlation test was used for statistical analysis. Results No correlation was found between f or D* and any of the parameters from the DCE-MRI in all patients or in patients with squamous cell carcinoma (p > 0.05). The ADC was significantly correlated with D values in the tumors (p < 0.001, r = 0.980) and muscles (p = 0.013, r = 0.542), despite its significantly higher value than D. The difference between ADC and D showed significant correlation with f values in the tumors (p = 0.017, r = 0.528) and muscles (p = 0.003, r = 0.630), but no correlation with D* (p > 0.05, respectively). Conclusion Intravoxel incoherent motion shows no significant correlation with model-free perfusion parameters derived from the DCE-MRI but is feasible for the analysis of diffusivity in both tumors and normal muscles of the head and neck. PMID:27587952

  2. Intravoxel Incoherent Motion Diffusion-Weighted MRI at 3.0 T Differentiates Malignant Breast Lesions From Benign Lesions and Breast Parenchyma

    PubMed Central

    Bokacheva, Louisa; Kaplan, Jennifer B.; Giri, Dilip D.; Patil, Sujata; Gnanasigamani, Merlin; Nyman, C. Gregory; Deasy, Joseph O.; Morris, Elizabeth A.; Thakur, Sunitha B.

    2016-01-01

    Purpose To study the differentiation of malignant breast lesions from benign lesions and fibroglandular tissue (FGT) using apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM) parameters. Materials and Methods This retrospective study included 26 malignant and 14 benign breast lesions in 35 patients who underwent diffusion-weighted MRI at 3.0T and nine b-values (0–1000 s/mm2). ADC and IVIM parameters (perfusion fraction fp, pseudodiffusion coefficient Dp, and true diffusion coefficient Dd) were determined in lesions and FGT. For comparison, IVIM was also measured in 16 high-risk normal patients. A predictive model was constructed using linear discriminant analysis. Lesion discrimination based on ADC and IVIM parameters was assessed using receiver operating characteristic (ROC) and area under the ROC curve (AUC). Results In FGT of normal subjects, fp was 1.1 ± 1.1%. In malignant lesions, fp (6.4 ± 3.1%) was significantly higher than in benign lesions (3.1 ± 3.3%, P = 0.0025) or FGT (1.5 ± 1.2%, P < 0.001), and Dd ((1.29 ± 0.28) × 10−3 mm2/s) was lower than in benign lesions ((1.56 ± 0.28) × 10−3 mm2/s, P = 0.011) or FGT ((1.86 ± 0.34) × 10−3 mm2/s, P < 0.001). A combination of Dd and fp provided higher AUC for discrimination between malignant and benign lesions (0.84) or FGT (0.97) than ADC (0.72 and 0.86, respectively). Conclusion The IVIM parameters provide accurate identification of malignant lesions. PMID:24273096

  3. The diagnostic value of 1.5-T diffusion-weighted MR imaging in detecting 5 to 10 mm metastatic cervical lymph nodes of nasopharyngeal carcinoma

    PubMed Central

    Jin, Guan Qiao; Yang, Jun; Liu, Li Dong; Su, Dan Ke; Wang, Duo Ping; Zhao, Sheng Fa; Liao, Zhi Ling

    2016-01-01

    Abstract The aim of the study was to prospectively assess the diagnostic accuracy of 1.5 T diffusion-weighted imaging (DWI) for 5 to 10 mm metastatic cervical lymph nodes of patients with nasopharyngeal carcinoma (NPC). All patients with histopathologically confirmed NPC underwent DWI with 2 b values of 0 and 800 s/mm2 were enrolled. The shortest axial diameter and mean apparent diffusion coefficient (ADC) value were recorded when lymph nodes with a shortest axial diameter from 5 to 10 mm were measured. The correlation between the pathological diagnoses and mean ADC values in the benign and metastatic lymph nodes were compared using the Z test. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic performance of DWI. Three hundred fourteen nodes of 52 patients with NPC consisted of 46.5% (146/314) metastatic lymph nodes and 53.5% (168/314) benign lymph nodes. The mean ADC value (×10–3 mm2/s) of benign lymph nodes was (1.110 ± 0.202), which was significantly higher than that of metastatic nodes (0.878 ± 0.159) (P < 0.05). The sensitivity, specificity, positive predictive value, and negative predictive value, accuracy for differentiating metastatic from benign lymph nodes using a cutoff ADC value of 0.924 × 10–3 mm2/s was 83.56%, 82.74%, 80.79%, 85.28%, and 82.80%, respectively. The area under the ROC curve was 0.851 (95% confidence intervals: 0.807–0.889). This study demonstrated that DWI is helpful in detecting 5 to 10 mm metastatic lymph nodes of patients with NPC. PMID:27512841

  4. Diffusion weighted imaging in gynecological malignancies - present and future

    PubMed Central

    Manoharan, Dinesh; Das, Chandan J; Aggarwal, Ankita; Gupta, Arun K

    2016-01-01

    The management of gynaecological malignancies has undergone a significant change in recent years with our improved understanding of cancer biogenetics, development of new treatment regimens and enhanced screening. Due to the rapid blooming of newer methods and techniques in gynaecology, surgery and oncology the scope and the role of imaging has also widened. Functional imaging in the form of diffusion weighted imaging (DWI) has been recently found to be very useful in assessing various tumours. Its ability to identify changes in the molecular level has dramatically changed the diagnostic approach of radiologists which was solely based on morphological criteria. It can improve the diagnostic accuracy of conventional magnetic resonance imaging, lend a hand in assessing tumour response to treatment regimens and detect tumour recurrence with better spatial resolution, negative radiation and diagnostic accuracy compared to positron emission tomography scan. The ability to quantify the diffusion has also lead to potential prediction of tumour aggressiveness and grade which directly correlate with the patient prognosis and management. Hence, it has become imperative for a radiologist to understand the concepts of DWI and its present and evolving role. In this article we present a brief description of the basics of DWI followed by its role in evaluation of female gynaecological malignancies. PMID:27027614

  5. Semiautomated spleen volumetry with diffusion-weighted MR imaging.

    PubMed

    Lee, Jeongjin; Kim, Kyoung Won; Lee, Ho; Lee, So Jung; Choi, Sanghyun; Jeong, Woo Kyoung; Kye, Heewon; Song, Gi-Won; Hwang, Shin; Lee, Sung-Gyu

    2012-07-01

    In this article, we determined the relative accuracy of semiautomated spleen volumetry with diffusion-weighted (DW) MR images compared to standard manual volumetry with DW-MR or CT images. Semiautomated spleen volumetry using simple thresholding followed by 3D and 2D connected component analysis was performed with DW-MR images. Manual spleen volumetry was performed on DW-MR and CT images. In this study, 35 potential live liver donor candidates were included. Semiautomated volumetry results were highly correlated with manual volumetry results using DW-MR (r = 0.99; P < 0.0001; mean percentage absolute difference, 1.43 ± 0.94) and CT (r = 0.99; P < 0.0001; 1.76 ± 1.07). Mean total processing time for semiautomated volumetry was significantly shorter compared to that of manual volumetry with DW-MR (P < 0.0001) and CT (P < 0.0001). In conclusion, semiautomated spleen volumetry with DW-MR images can be performed rapidly and accurately when compared with standard manual volumetry. PMID:22161960

  6. Diffusion weighted imaging in gynecological malignancies - present and future.

    PubMed

    Manoharan, Dinesh; Das, Chandan J; Aggarwal, Ankita; Gupta, Arun K

    2016-03-28

    The management of gynaecological malignancies has undergone a significant change in recent years with our improved understanding of cancer biogenetics, development of new treatment regimens and enhanced screening. Due to the rapid blooming of newer methods and techniques in gynaecology, surgery and oncology the scope and the role of imaging has also widened. Functional imaging in the form of diffusion weighted imaging (DWI) has been recently found to be very useful in assessing various tumours. Its ability to identify changes in the molecular level has dramatically changed the diagnostic approach of radiologists which was solely based on morphological criteria. It can improve the diagnostic accuracy of conventional magnetic resonance imaging, lend a hand in assessing tumour response to treatment regimens and detect tumour recurrence with better spatial resolution, negative radiation and diagnostic accuracy compared to positron emission tomography scan. The ability to quantify the diffusion has also lead to potential prediction of tumour aggressiveness and grade which directly correlate with the patient prognosis and management. Hence, it has become imperative for a radiologist to understand the concepts of DWI and its present and evolving role. In this article we present a brief description of the basics of DWI followed by its role in evaluation of female gynaecological malignancies. PMID:27027614

  7. Role of diffusion weighted imaging in diagnosis of post transplant lymphoproliferative disorders: Case reports and review of literature

    PubMed Central

    Singh, A.; Das, C. J.; Gupta, A. K.; Bagchi, S.

    2016-01-01

    Post transplant lymphoproliferative disorder include a spectrum of conditions occurring in immunosuppressed post transplant recipients, lymphoma being the most ominous. 18F-fludeoxyglucose positron emission tomography with computed tomography CT) is the current imaging gold standard for lymphoma imaging as it allows both morphological and functional assessment. CT and/or conventional magnetic resonance imaging (MRI) are used for morphological evaluation in transplant recipients. Integrating diffusion weighted imaging with apparent diffusion coefficient analysis in MRI protocol enhances its sensitivity and may prove invaluable in response assessment in transplant recipients. PMID:27194838

  8. Integration of diffusion-weighted MRI data and a simple mathematical model to predict breast tumor cellularity during neoadjuvant chemotherapy.

    PubMed

    Atuegwu, Nkiruka C; Arlinghaus, Lori R; Li, Xia; Welch, E Brian; Chakravarthy, Bapsi A; Gore, John C; Yankeelov, Thomas E

    2011-12-01

    Diffusion-weighted magnetic resonance imaging data obtained early in the course of therapy can be used to estimate tumor proliferation rates, and the estimated rates can be used to predict tumor cellularity at the conclusion of therapy. Six patients underwent diffusion-weighted magnetic resonance imaging immediately before, after one cycle, and after all cycles of neoadjuvant chemotherapy. Apparent diffusion coefficient values were calculated for each voxel and for a whole tumor region of interest. Proliferation rates were estimated using the apparent diffusion coefficient data from the first two time points and then used with the logistic model of tumor growth to predict cellularity after therapy. The predicted number of tumor cells was then correlated to the corresponding experimental data. Pearson's correlation coefficient for the region of interest analysis yielded 0.95 (P = 0.004), and, after applying a 3 × 3 mean filter to the apparent diffusion coefficient data, the voxel-by-voxel analysis yielded a Pearson correlation coefficient of 0.70 ± 0.10 (P < 0.05). PMID:21956404

  9. Intravoxel incoherent motion diffusion-weighted imaging for monitoring chemotherapeutic efficacy in gastric cancer

    PubMed Central

    Song, Xiao-Li; Kang, Heoung Keun; Jeong, Gwang Woo; Ahn, Kyu Youn; Jeong, Yong Yeon; Kang, Yang Joon; Cho, Hye Jung; Moon, Chung Man

    2016-01-01

    AIM: To assess intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) for monitoring early efficacy of chemotherapy in a human gastric cancer mouse model. METHODS: IVIM-DWI was performed with 12 b-values (0-800 s/mm2) in 25 human gastric cancer-bearing nude mice at baseline (day 0), and then they were randomly divided into control and 1-, 3-, 5- and 7-d treatment groups (n = 5 per group). The control group underwent longitudinal MRI scans at days 1, 3, 5 and 7, and the treatment groups underwent subsequent MRI scans after a specified 5-fluorouracil/calcium folinate treatment. Together with tumor volumes (TV), the apparent diffusion coefficient (ADC) and IVIM parameters [true water molecular diffusion coefficient (D), perfusion fraction (f) and pseudo-related diffusion coefficient (D*)] were measured. The differences in those parameters from baseline to each measurement (ΔTV%, ΔADC%, ΔD%, Δf% and ΔD*%) were calculated. After image acquisition, tumor necrosis, microvessel density (MVD) and cellular apoptosis were evaluated by hematoxylin-eosin (HE), CD31 and terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) staining respectively, to confirm the imaging findings. Mann-Whitney test and Spearman's correlation coefficient analysis were performed. RESULTS: The observed relative volume increase (ΔTV%) in the treatment group were significantly smaller than those in the control group at day 5 (ΔTVtreatment% = 19.63% ± 3.01% and ΔTVcontrol% = 83.60% ± 14.87%, P = 0.008) and day 7 (ΔTVtreatment% = 29.07% ± 10.01% and ΔTVcontrol% = 177.06% ± 63.00%, P = 0.008). The difference in ΔTV% between the treatment and the control groups was not significant at days 1 and 3 after a short duration of treatment. Increases in ADC in the treatment group (ΔADC%treatment, median, 30.10% ± 18.32%, 36.11% ± 21.82%, 45.22% ± 24.36%) were significantly higher compared with the control group (ΔADC%control, median, 4.98% ± 3.39%, 6.26% ± 3

  10. The Role of Apparent Diffusion Coefficient Quantification in Differentiating Benign and Malignant Renal Masses by 3 Tesla Magnetic Resonance Imaging

    PubMed Central

    Göya, Cemil; Hamidi, Cihad; Bozkurt, Yaşar; Yavuz, Alpaslan; Kuday, Suzan; Gümüş, Hatice; Türkçü, Gül; Hattapoğlu, Salih; Bilici, Aslan

    2015-01-01

    Background: Diffusion-weighted magnetic resonance imaging (DWI) is a widely-accepted diagnostic modality whose efficacy has been investigated by numerous past studies in the differentiation of malignant lesions from benign entities. Aims: The aim of this study was to evaluate the efficiency of diffusion-weighted magnetic resonance imaging in the characterization of renal lesions. Study Design: Diagnostic accuracy study. Methods: A total of 137 patients with renal lesions were included in this study. The median apparent diffusion coefficient (ADC) values as well as the b 800 and b 1600 signal intensities of normal kidneys, solid components of mixed renal masses, and total cystic lesions were evaluated. Results: There were significant differences between the ADC values of lesions and normal renal parenchyma, and between the ADC values of benign and malignant renal lesions on DWIs at b values of 800 and 1600 s/mm2 (p<0.001 and p<0.001, respectively). There were significant differences between the ADC values of Bosniak Category 1 and 2 cysts and the ADC values of Bosniak Category 1 and 3 cysts on DWIs at b values of 800 s/mm2 (p<0.001) and 1600 s/mm2 (p<0.001). A cutoff value of 1.902 × 10−3 mm2/s for the ADC with a b value of 800 s/mm2 provided 88% sensitivity and 96% specificity for differentiation between benign and malignant renal lesions. A cutoff value of 1.623 × 10−3 mm2/s for the ADC with a b value of 1600 s/mm2 provided 79% sensitivity and 96% specificity (p<0.001) for the differentiation between benign and malignant renal lesions. Conclusion: Accurate assessment of renal masses is important for determining the necessity for surgical intervention. DWI provides additional value by differentiating benign from malignant renal tumors and can be added to routine kidney MRI protocols. PMID:26185715

  11. Intravoxel incoherent motion diffusion-weighted imaging in differentiating uterine fibroid from focal adenomyosis: initial results.

    PubMed

    Tian, Tao; Zhang, Guo-Fu; Zhang, He; Liu, Hui

    2016-01-01

    To evaluate the performance of intravoxel incoherent motion (IVIM)-diffusion-weighted imaging (DWI) in differentiating uterine fibroids from focal adenomyosises. Twenty-five uterine fibroids and 21 focal adenomyosises prospectively underwent IVIM-DWI examination prior to surgery. Four parameters including apparent diffusion coefficient total values (ADCtot), true diffusion coefficient (D), pseudodiffusion coefficient (D*) and perfusion fraction (f) derived from IVIM-DWI images were separately calculated and compared across four groups. There was a statistically significant difference in IVIM-derived f parameter between fibroid and focal adenomyosis (p = 0.01) and control group (p = 0.02). Uterine fibroids gave higher coefficient of variation (CV) of all IVIM-derived parameters than focal adenomyosises. IVIM-DWI could improve the sensitivity and specificity of detecting focal adenomyosis to 100 and 92.6 %, respectively. IVIM-f parameter could be potentially used to better distinguish uterine fibroid from focal adenomyosis. The higher CV of IVIM-derived parameters with acceptable range is often observed in the diseased group. PMID:26759748

  12. Diffusion-Weighted MRI Reflects Proliferative Activity in Primary CNS Lymphoma

    PubMed Central

    Meyer, Jonas; Gawlitza, Matthias; Frydrychowicz, Clara; Müller, Wolf; Preuss, Matthias; Bure, Lionel; Quäschling, Ulf; Hoffmann, Karl-Titus; Surov, Alexey

    2016-01-01

    Purpose To investigate if apparent diffusion coefficient (ADC) values within primary central nervous system lymphoma correlate with cellularity and proliferative activity in corresponding histological samples. Materials and Methods Echo-planar diffusion-weighted magnetic resonance images obtained from 21 patients with primary central nervous system lymphoma were reviewed retrospectively. Regions of interest were drawn on ADC maps corresponding to the contrast enhancing parts of the tumors. Biopsies from all 21 patients were histologically analyzed. Nuclei count, total nuclei area and average nuclei area were measured. The proliferation index was estimated as Ki-67 positive nuclei divided by total number of nuclei. Correlations of ADC values and histopathologic parameters were determined statistically. Results Ki-67 staining revealed a statistically significant correlation with ADCmin (r = -0.454, p = 0.038), ADCmean (r = -0.546, p = 0.010) and ADCmax (r = -0.515, p = 0.017). Furthermore, ADCmean correlated in a statistically significant manner with total nucleic area (r = -0.500, p = 0.021). Conclusion Low ADCmin, ADCmean and ADCmax values reflect a high proliferative activity of primary cental nervous system lymphoma. Low ADCmean values—in concordance with several previously published studies—indicate an increased cellularity within the tumor. PMID:27571268

  13. Prognostic role for diffusion-weighted imaging of pediatric optic pathway glioma.

    PubMed

    Yeom, K W; Lober, R M; Andre, J B; Fisher, P G; Barnes, P D; Edwards, M S B; Partap, S

    2013-07-01

    Optic pathway glioma (OPG) has an unpredictable course, with poor correlation between conventional imaging features and tumor progression. We investigated whether diffusion-weighted MRI (DWI) predicts the clinical behavior of these tumors. Twelve children with OPG (median age 2.7 years; range 0.4-6.2 years) were followed for a median 4.4 years with DWI. Progression-free survival (time to requiring therapy) was compared between tumors stratified by apparent diffusion coefficient (ADC) from initial pre-treatment scans. Tumors with baseline ADC greater than 1,400 × 10(-6) mm(2)/s required treatment earlier than those with lower ADC (log-rank p = 0.002). In some cases, ADC increased leading up to treatment, and declined following treatment with surgery, chemotherapy, or radiation. Baseline ADC was higher in tumors that eventually required treatment (1,562 ± 192 × 10(-6) mm(2)/s), compared with those conservatively managed (1,123 ± 114 × 10(-6) mm(2)/s) (Kruskal-Wallis test p = 0.013). Higher ADC predicted earlier tumor progression in this cohort and in some cases declined after therapy. Evaluation of OPG with DWI may therefore be useful for predicting tumor behavior and assessing treatment response. PMID:23673514

  14. Diffusion-weighted MRI findings and clinical correlations in sporadic Creutzfeldt-Jakob disease.

    PubMed

    Gao, Ting; Lyu, Jin-Hao; Zhang, Jia-Tang; Lou, Xin; Zhao, Wei; Xing, Xiao-Wei; Yang, Ming; Yao, Yan; Tan, Qing-Che; Tian, Cheng-Lin; Huang, Xu-Sheng; Ma, Lin; Yu, Sheng-Yuan

    2015-06-01

    The objective of this study is to investigate the hyperintense lesions on diffusion-weighted magnetic resonance imaging (DWI) and its clinical correlation in sporadic Creutzfeldt-Jakob disease (sCJD). Patients who suffered from sCJD and followed up at the Department of Neurology at the General Hospital of the People's Liberation Army during the period of June 1, 2007 to July 1, 2014 were reviewed. The location of the hyperintense lesions on DWI, apparent diffusion coefficient (ADC) values of the hyperintense lesions were correlated with symptoms and clinical course. A total of 58 sCJD patients and ten healthy controls were included. Hyperintense lesions on DWI were observed in all the patients. The patients with basal ganglia (BG) hyperintense lesions on DWI had shorter disease duration and higher incidence of myoclonus (92 versus 44 %) than those without BG hyperintense lesions. The patients with occipital cortex hyperintense lesions on DWI had shorter disease duration between symptom onset and akinetic mutism than those without these lesions. The lower of the BG ADC value the faster presence of akinetic mutism and the shorter disease duration the patients will have. The presence of BG and occipital cortex hyperintense lesions on DWI and BG ADC values is correlated with the clinical course and clinical symptoms. PMID:25860342

  15. Role of diffusion-weighted imaging in the diagnosis of gynecological diseases.

    PubMed

    Namimoto, Tomohiro; Awai, Kazuo; Nakaura, Takeshi; Yanaga, Yumi; Hirai, Toshinori; Yamashita, Yasuyuki

    2009-03-01

    Recent technical advances in diffusion-weighted imaging (DWI) greatly enhanced the clinical value of magnetic resonance imaging (MRI) of the body. DWI can provide excellent tissue contrast based on molecular diffusion and may be able to demonstrate malignant tumors. Quantitative measurement of the apparent diffusion coefficient (ADC) may be valuable in distinguishing between malignant and benign lesions. We reviewed DWI and conventional MRI of the female pelvis to study the utility of DWI in patients with gynecological diseases. Although the ADC can help to differentiate between normal and cancerous tissue in the uterine cervix and endometrium, its utility may be limited by the large overlap of the uterine myometrium and ovaries. On the other hand, the ADC may be useful for monitoring the therapeutic outcome after uterine arterial embolizati (UAE), chemotherapy and/or radiation therapy. In patients with ovarian cancer, DWI demonstrates high intensity not only at the primary cancer site but also in disseminated peritoneal implants. When added to conventional MRI findings, DWI and ADC values provide additional information and DWI may play an important role in the diagnosis of patients with gynecological diseases. PMID:18839179

  16. Anomalous diffusion of brain metabolites evidenced by diffusion-weighted magnetic resonance spectroscopy in vivo

    PubMed Central

    Marchadour, Charlotte; Brouillet, Emmanuel; Hantraye, Philippe; Lebon, Vincent; Valette, Julien

    2012-01-01

    Translational displacement of molecules within cells is a key process in cellular biology. Molecular motion potentially depends on many factors, including active transport, cytosol viscosity and molecular crowding, tortuosity resulting from cytoskeleton and organelles, and restriction barriers. However, the relative contribution of these factors to molecular motion in the cytoplasm remains poorly understood. In this work, we designed an original diffusion-weighted magnetic resonance spectroscopy strategy to probe molecular motion at subcellular scales in vivo. This led to the first observation of anomalous diffusion, that is, dependence of the apparent diffusion coefficient (ADC) on the diffusion time, for endogenous intracellular metabolites in the brain. The observed increase of the ADC at short diffusion time yields evidence that metabolite motion is characteristic of hindered random diffusion rather than active transport, for time scales up to the dozen milliseconds. Armed with this knowledge, data modeling based on geometrically constrained diffusion was performed. Results suggest that metabolite diffusion occurs in a low-viscosity cytosol hindered by ∼2-μm structures, which is consistent with known intracellular organization. PMID:22929443

  17. Distinction Between Recurrent Glioma and Radiation Injury Using Magnetic Resonance Spectroscopy in Combination With Diffusion-Weighted Imaging

    SciTech Connect

    Zeng, Q.-S. . E-mail: nanwushan@yahoo.com; Li, C.-F.; Liu Hong; Zhen, J.-H.; Feng, D.-C.

    2007-05-01

    Purpose: The aim of this study was to explore the diagnostic effectiveness of magnetic resonance (MR) spectroscopy with diffusion-weighted imaging on the evaluation of the recurrent contrast-enhancing areas at the site of treated gliomas. Methods and Materials: In 55 patients who had new contrast-enhancing lesions in the vicinity of the previously resected and irradiated high-grade gliomas, two-dimensional MR spectroscopy and diffusion-weighted imaging were performed. Spectral data for N-acetylaspartate (NAA), choline (Cho), creatine (Cr), lipid (Lip), and lactate (Lac) were analyzed in conjunction with the apparent diffusion coefficient (ADC) in all patients. Diagnosis of these lesions was assigned by means of follow-up or histopathology. Results: The Cho/NAA and Cho/Cr ratios were significantly higher in recurrent tumor than in regions of radiation injury (p < 0.01). The ADC value and ADC ratios (ADC of contrast-enhancing lesion to matching structure in the contralateral hemisphere) were significantly higher in radiation injury regions than in recurrent tumor (p < 0.01). With MR spectroscopic data, two variables (Cho/NAA and Cho/Cr ratios) were shown to differentiate recurrent glioma from radiation injury, and 85.5% of total subjects were correctly classified into groups. However, with discriminant analysis of MR spectroscopy imaging plus diffusion-weighted imaging, three variables (Cho/NAA, Cho/Cr, and ADC ratio) were identified and 96.4% of total subjects were correctly classified. There was a significant difference between the diagnostic accuracy of the two discriminant analyses (Chi-square = 3.96, p = 0.046). Conclusion: Using discriminant analysis, this study found that MR spectroscopy in combination with ADC ratio, rather than ADC value, can improve the ability to differentiate recurrent glioma and radiation injury.

  18. Challenges in determining b value in the Northwest Geysers

    SciTech Connect

    Saltiel, S.; Boyle, K.; Majer, E.

    2011-02-01

    Past analyses of the Gutenberg-Richter b-value in the Geysers and other geothermal settings have revealed a deviation from the assumed linear relationship in log space between magnitude and the number of earthquakes. In this study of the Northwest Geysers, we found a gently-sloping discontinuity in the b-value curve. This is especially apparent when comparing the least-squares fit (LSQ) of the curve to the fit obtained by the maximum likelihood estimation (MLE), a widely-respected method of analyzing magnitude-frequency relationships. This study will describe the assumptions made when using each of these two methods and will also explore how they can be used in conjunction to investigate the characteristics of the observed b-value curve. To understand whether slope-fit differences in the LSQR and MLE methods is due to physical properties of the system or due to artifacts from errors in sampling, it is extremely important to consider the catalog completeness, magnitude bin size, number of events, and differences in source mechanisms for the events comprising the study volume. This work will hopefully lead to informative interpretations of frequency-magnitude curves for the Northwest Geysers, a geothermal area of ongoing high-volume coldwater injection and steam production. Through this statistical investigation of the catalog contents, we hope to better understand the dominant source mechanisms and the role of injected fluids in the creation of seismic clustering around nearly 60 wells of varying depths and injection volumes.

  19. Usefulness of diffusion-weighted MRI with echo-planar technique in the evaluation of cellularity in gliomas.

    PubMed

    Sugahara, T; Korogi, Y; Kochi, M; Ikushima, I; Shigematu, Y; Hirai, T; Okuda, T; Liang, L; Ge, Y; Komohara, Y; Ushio, Y; Takahashi, M

    1999-01-01

    The purpose of this study was to evaluate the utility of diffusion-weighted magnetic resonance imaging (MRI) with echo-planar imaging (EPI) technique in depicting the tumor cellularity and grading of gliomas. Twenty consecutive patients (13 men and 7 women, ranging in age from 13 to 69 years) with histologically proven gliomas were examined using a 1.5 T superconducting imager. Tumor cellularity, analyzed with National Institutes of Health Image 1.60 software on a Macintosh computer, was compared with the minimum apparent diffusion coefficient (ADC) and the signal intensity on the T2-weighted images. The relationship of the minimum ADC to the tumor grade was also evaluated. Tumor cellularity correlated well with the minimum ADC value of the gliomas (P = 0.007), but not with the signal intensity on the T2-weighted images. The minimum ADC of the high-grade gliomas was significantly higher than that of the low-grade gliomas. Diffusion-weighted MRI with EPI is a useful technique for assessing the tumor cellularity and grading of gliomas. This information is not obtained with conventional MRI and is useful for the diagnosis and characterization of gliomas. PMID:10030650

  20. Resolution of early diffusion-weighted and FLAIR MRI abnormalities in a patient with TIA.

    PubMed

    Lecouvet, F E; Duprez, T P; Raymackers, J M; Peeters, A; Cosnard, G

    1999-03-23

    We report a patient with a clinical history and neurologic examination consistent with acute stroke. Diffusion-weighted and fast fluid-attenuated inversion recovery MRI obtained 4 hours after stroke onset detected focal abnormalities suggestive of acute ischemic brain damage. The neurologic deficit and the imaging abnormalities both resolved completely at follow-up. This patient illustrates complete resolution of early changes observed with diffusion-weighted MRI at the hyperacute phase in a TIA. PMID:10102438

  1. Diffusion-weighted MRI in differentiating malignant from benign thyroid nodules: a meta-analysis

    PubMed Central

    Chen, Lihua; Xu, Jian; Bao, Jing; Huang, Xuequan; Hu, Xiaofei; Xia, Yunbao; Wang, Jian

    2016-01-01

    Objectives To perform a meta-analysis to evaluate the diagnostic efficacy of diffusion-weighted imaging (DWI) in differentiating malignant from benign thyroid nodules. Design A meta-analysis. Data sources and study selection Medical and scientific literature databases were searched for original articles published up to August 2015. Studies were selected if they (1) included diagnostic DWI for differentiating malignant from benign thyroid lesions, (2) included patients who later underwent biopsy and (3) presented sufficient data to enable the construction of contingency tables. Data synthesis For each study, the true-positive, false-positive, true-negative and false-negative values were extracted or derived, and 2×2 contingency tables were constructed. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) instrument. The heterogeneity test, threshold effect test, subgroup analyses and publication bias analyses were performed. Results From the 113 identified search results, 15 studies, representing a total of 765 lesions, were included in the meta-analysis. We detected heterogeneity between studies but found no evidence of publication bias. The methodological quality was moderate. The pooled weighted sensitivity was 0.90 (95% CI 0.85 to 0.93); the specificity was 0.95 (95% CI 0.88 to 0.98); the positive likelihood ratio was 16.49 (95% CI 7.37 to 36.86); the negative likelihood ratio was 0.11 (95% CI 0.08 to 0.16); and the diagnostic OR was 150.73 (95% CI 64.96 to 349.75). The area under the receiver operator characteristic curve was 0.95 (95% CI 0.93 to 0.97). Conclusions Quantitative DWI may be a non-invasive, non-radiative and accurate method of distinguishing malignant from benign thyroid nodules. Nevertheless, large-scale trials are necessary to assess its clinical value and to establish standards regarding b values and cut-off values for DWI-based diagnosis. PMID:26733564

  2. Diagnostic Performance of Diffusion-weighted Magnetic Resonance Imaging in Bone Malignancy

    PubMed Central

    Liu, Li-Peng; Cui, Long-Biao; Zhang, Xin-Xin; Cao, Jing; Chang, Ning; Tang, Xing; Qi, Shun; Zhang, Xiao-Liang; Yin, Hong; Zhang, Jian

    2015-01-01

    Abstract Current state-of-the-art nuclear medicine imaging methods (such as PET/CT or bone scintigraphy) may have insufficient sensitivity for predicting bone tumor, and substantial exposure to ionizing radiation is associated with the risk of secondary cancer development. Diffusion-weighted MRI (DW-MRI) is radiation free and requires no intravenous contrast media, and hence is more suitable for population groups that are vulnerable to ionizing radiation and/or impaired renal functions. This meta-analysis was conducted to investigate whether whole-body DW-MRI is a viable means in differentiating bone malignancy. Medline and Embase databases were searched from their inception to May 2015 without language restriction for studies evaluating DW-MRI for detection of bone lesions. Methodological quality was assessed by the quality assessment of diagnostic studies (QUADAS-2) instrument. Sensitivities, specificities, diagnostic odds ratio (DOR), and areas under the curve (AUC) were used as measures of the diagnostic accuracy. We combined the effects by using the random-effects mode. Potential threshold effects and publication bias were investigated. We included data from 32 studies with 1507 patients. The pooled sensitivity, specificity, and AUC were 0.95 (95% CI, 0.90–0.97), 0.92 (95% CI, 0.88–0.95), and 0.98 on a per-patient basis, and they were 0.91 (95% CI, 0.87–0.94), 0.94 (95% CI, 0.90–0.96), and 0.97 on a per-lesion basis. In subgroup analysis, there is no statistical significance found in the sensitivity and specificity of using DWI only and DWI combined with other morphological or functional imaging sequence in both basis (P > 0.05). A b value of 750 to 1000 s/mm2 enables higher AUC and DOR for whole-body imaging purpose when compared with other values in both basis either (P < 0.01). The ROC space did not show a curvilinear trend of points and a threshold effect was not observed. According to the Deek's plots, there was no publication bias on

  3. Detection of electroporation-induced membrane permeabilization states in the brain using diffusion-weighted MRI

    PubMed Central

    Mahmood, Faisal; Hansen, Rasmus H.; Agerholm-Larsen, Birgit; Gissel, Hanne; Ibsen, Per

    2015-01-01

    Background Tissue permeabilization by electroporation (EP) is a promising technique to treat certain cancers. Non-invasive methods for verification of induced permeabilization are important, especially in deep-seated cancers. In this study we evaluated diffusion-weighted magnetic resonance imaging (DW-MRI) as a quantitative method for detecting EP-induced membrane permeabilization of brain tissue using a rat brain model. Material and methods Fifty-four anesthetized Sprague-Dawley male rats were electroporated in the right hemisphere, using different voltage levels to induce no permeabilization (NP), transient membrane permeabilization (TMP), and permanent membrane permeabilization (PMP), respectively. DW-MRI was acquired 5 minutes, 2 hours, 24 hours and 48 hours after EP. Histology was performed for validation of the permeabilization states. Tissue content of water, Na+, K+, Ca2+, and extracellular volume were determined. The Kruskal-Wallis test was used to compare the DW-MRI parameters, apparent diffusion coefficient (ADC) and kurtosis, at different voltage levels. The two-sample Mann- Whitney test with Holm's Bonferroni correction was used to identify pairs of significantly different groups. The study was approved by the Danish Animal Experiments Inspectorate. Results and conclusion Results showed significant difference in the ADC between TMP and PMP at 2 hours (p < 0.001) and 24 hours (p < 0.05) after EP. Kurtosis was significantly increased both at TMP (p < 0.05) and PMP (p < 0.001) 5 minutes after EP, compared to NP. Kurtosis was also significantly higher at 24 hours (p < 0.05) and 48 hours (p < 0.05) at PMP compared to NP. Physiological parameters indicated correlation with the permeabilization states, supporting the DW-MRI findings. We conclude that DW-MRI is capable of detecting EP-induced permeabilization of brain tissue and to some extent of differentiating NP, TMP and PMP using appropriate scan timing. PMID:25591820

  4. Diffusion-weighted imaging in extracranial head and neck schwannomas: A distinctive appearance

    PubMed Central

    Das, Abanti; Bhalla, Ashu S; Sharma, Raju; Kumar, Atin; Thakar, Alok; Goyal, Ankur

    2016-01-01

    Purpose: To evaluate the diffusion weighted (DW) magnetic resonance imaging (MRI) features of the extracranial schwannomas of head and neck. Materials and Methods: The MRI (including DWI) of 12 patients with pathologically proven head and neck schwannomas (4 men, 8 women, with mean age of 32.6 years; age range 16–50 years) were retrospectively evaluated. Images were analyzed for signal intensity and morphology on conventional sequences followed by the qualitative evaluation of DW images (DWI) and measurement of apparent diffusion coefficient (ADC) values. Results: Majority of the tumors were located in the parapharyngeal space (8/12). All but one showed heterogeneous appearance, with 10 tumors showing scattered areas of hemorrhage. Eight out of 12 tumors showed intensely hyperintense core surrounded by intermediate signal intensity peripheral rim (reverse target sign) on T2-weighted (T2W) images. On DWI, these eight tumors showed a distinctive appearance, resembling target sign on trace DWI and reverse target on ADC map. Out of the remaining four tumors, one showed uniformly restricted diffusion whereas three showed free diffusion. Mean ADC value in the central area of free diffusion was 2.277 × 10−3 mm2/s (range of 1.790 × 10 −3 to 2.605 × 10−3 mm2/s) whereas in the peripheral area was 1.117 × 10−3 mm2/s (range of 0.656 × 10−3 to 1.701 × 10−3 mm2/s). Rest of the schwannomas showing free diffusion had a mean ADC value of 1.971 × 10−3 mm2/s. Conclusion: Majority of the head and neck schwannomas showed a characteristic appearance of free diffusion in the centre and restricted diffusion in the periphery of the mass. PMID:27413271

  5. Focal nodular hyperplasia: characterisation at gadoxetic acid-enhanced MRI and diffusion-weighted MRI

    PubMed Central

    An, H S; Kim, Y J; Jung, S I; Jeon, H J

    2013-01-01

    Purpose: The aim of this study was to assess the enhancement patterns of hepatic focal nodular hyperplasia (FNH) on gadoxetic acid-enhanced MRI and diffusion-weighted (DW) MRI. Methods: This retrospective study had institutional review board approval. Gadoxetic acid-enhanced and DW MR images were evaluated in 23 patients with 30 FNHs (26 histologically proven and 4 radiologically diagnosed). The lesion enhancement patterns of the hepatobiliary phase images were classified as heterogeneous or homogeneous signal intensity (SI), and as dominantly high/iso or low SI compared with those of adjacent liver parenchyma. Heterogeneous (any) SI lesions and homogeneous low SI lesions were categorised into the fibrosis group, whereas homogeneous high/iso SI lesions were categorised into the non-fibrosis group. Additionally, lesion SI on T2 weighted images, DW images and apparent diffusion coefficient (ADC) values were compared between the two groups. Results: The lesions showed heterogeneous high/iso SI (n=16), heterogeneous low SI (n=5), homogeneous high/iso SI (n=7) or homogeneous low SI (n=2) at the hepatobiliary phase MR images. The fibrosis group lesions were more likely to show high SI on DW images and T2 weighted images compared with those in the non-fibrosis group (p<0.05). ADC values tended to be lower in the fibrosis group than those in the non-fibrosis group without significance. Conclusion: FNH showed variable enhancement patterns on hepatobiliary phase images during gadoxetic acid-enhanced MRI. SI on DW and T2 weighted images differed according to the fibrosis component contained in the lesion. Advances in knowledge: FNH shows a wide spectrum of imaging findings on gadoxetic acid-enhanced MRI and DW MRI. PMID:23873903

  6. Prediction of background parenchymal enhancement on breast MRI using mammography, ultrasonography, and diffusion-weighted imaging

    PubMed Central

    Kawamura, Akiko; Satake, Hiroko; Ishigaki, Satoko; Ikeda, Mitsuru; Kimura, Reiko; Shimamoto, Kazuhiro; Naganawa, Shinji

    2015-01-01

    ABSTRACT This retrospective study assessed the effects of menopausal status and menstrual cycle on background parenchymal enhancement (BPE) of breast magnetic resonance imaging (MRI), and investigated whether the degree of BPE can be predicted by findings of mammography, ultrasonography (US), and diffusion-weighted MR imaging (DWI). There were 160 study patients (80 premenopausal, 80 postmenopausal). Degree of BPE was classified into minimal, mild, moderate, or marked. Mammographic density was classified into fatty, scattered, heterogeneously dense, and extremely dense. BP echotexture on US and BP intensity on DWI were visually classified as homogeneous or heterogeneous. Apparent diffusion coefficient (ADC) values of normal breast tissue were measured. Associations of the degree of BPE with menopausal status, menstrual cycle, or imaging features were evaluated by univariate and multivariate analyses. No significant correlation was found between mammographic density and BPE (p=0.085), whereas menopausal status (p=0.000), BP echotexture (p=0.000), and BP intensity on DWI (p= 0.000), and ADC values (p=0.000) showed significant correlations with BPE. Multivariate analysis showed that postmenopausal status was an independent predictor of minimal BPE (p=0.002, OR=3.743). In premenopausal women, there was no significant correlation between menstrual cycle and BPE, whereas BP echotexture was an independent predictor of whether BPE was less than mild or greater than moderate (p=0.001, OR=26.575). BPE on breast MRI is associated with menopausal status and the findings of US and DWI. Because premenopausal women with heterogeneous BP echotexture may be predicted to show moderate or marked BPE, scheduling of breast MRI should preferentially be adjusted to the menstrual cycle. PMID:26412889

  7. Diagnostic significance of diffusion-weighted MRI in patients with cervical cancer: a meta-analysis.

    PubMed

    Hou, Bo; Xiang, Shi-Feng; Yao, Gen-Dong; Yang, Su-Jun; Wang, Yu-Fang; Zhang, Yi-Xin; Wang, Jun-Wei

    2014-12-01

    The aim of this meta-analysis is to demonstrate whether diffusion-weighted magnetic resonance imaging (DWI) could assist in the precise diagnosis of cervical cancer or not. Both English and Chinese electronic databases were searched for potential relevant studies followed by a comprehensive literature search without any language restriction. Two reviewers independently assessed the methodological quality of the included trials. Standardized mean difference (SMD) and its corresponding 95 % confidence interval (95 % CI) were calculated in this meta-analysis. We chose Version 12.0 STATA statistical software to analyze our statistical data. Thirteen eligible cohort studies were selected for statistical analysis, including 645 tumor tissues and 504 normal tissues. Combined SMD of apparent diffusion coefficient (ADC) suggested that the ADC value in cervical cancer tissues was significantly lower than that of normal tissue (SMD = 2.80, 95 % CI = 2.64 ~ 2.96, P < 0.001). Subgroup analysis stratified by ethnicity indicated a higher ADC value in the normal tissues compared to the cancer tissues in both the Asian and Caucasian subgroups (Asians: SMD = 2.83, 95 % CI = 2.64 ~ 3.02, P < 0.001; Caucasians: SMD = 2.73, 95 % CI = 2.45 ~ 3.01, P < 0.001, respectively). The results from the subgroup analysis by MRI machine type revealed a statistically significant difference in ADC value between normal cervical tissue and tumor tissues among all of the six MRI machine type subgroups (all P < 0.05). The main finding from our meta-analysis revealed that increased signal intensity on DWI and decreased signal on ADC seem to be useful in the diagnosis of cervical cancer. DWI could therefore be an important imaging tool in potentially identifying patients with cervical cancer. PMID:25168365

  8. The role of diffusion-weighted magnetic resonance imaging in the classification of hepatic hydatid cysts.

    PubMed

    Ceçe, Hasan; Gündoğan, Mehmet; Karakaş, Omer; Karakaş, Ekrem; Boyacı, Fatıma Nurefşan; Yıldız, Sema; Ozgönül, Abdullah; Karakaş, Emel Yiğit; Cullu, Neşat; Seker, Ahmet

    2013-01-01

    The aim of the study was to classify different types of hepatic hydatid cysts (HHCs) by measuring the mean apparent diffusion coefficient (ADC) using diffusion-weighted magnetic resonance imaging (DWI). This prospective study comprised 44 patients. The 44 HHCs were classified using Gharbi ultrasonographic classification (GUC) and then T2WIs and DWIs were obtained. The ADC values were measured of the hydatid cyst (HC) subtypes. The distribution of the ADC values in the cyst groups was compared using the Kruskal-Wallis test for multi groups and the Mann-Whitney U test for paired groups. To evaluate the efficacy of ADC values in cyst diagnosis, receiver operating characteristic (ROC) analysis was performed. According to the GUC, there were 15 type 1, 11 type 2, 7 type 3, 5 type 4 and 6 type 5 HHCs. According to the ADC values in the paired comparisons, while types 1, 2 and 5 HCs were statistically differentiated from all other groups except the type 3 group, the type 4 group was differentiated from all other groups and the type 3 group was only differentiated from the type 4 group. When two groups were formed from the HHC subtypes with types 1, 2, and 3 in one group and types 4 and 5 in the other, a statistically significant difference was determined in the mean ADC values of these new groups. In conclusion the measurement of ADC values can be considered a promising parameter as an alternative to ultrasonography in the determination of subtypes of HHCs. PMID:23177089

  9. Diffusion-weighted MRI for imaging cell death after cytotoxic or apoptosis-inducing therapy

    PubMed Central

    Papaevangelou, E; Almeida, G S; Jamin, Y; Robinson, S P; deSouza, N M

    2015-01-01

    Background: Non-invasive serial imaging is desirable to detect processes such as necrotic and apoptotic cell death in cancer patients undergoing treatment. This study investigated the use of diffusion-weighted (DW-) magnetic resonance imaging (MRI) for imaging cell death induced by either a cytotoxic drug (irinotecan), or the apoptosis-inducing agent birinapant, in human tumour xenografts in vivo. Methods: Nude mice bearing human SW620 colon carcinoma xenografts were treated with vehicle, irinotecan (50 mg kg−1) or birinapant (30 mg kg−1) for up to 5 days. DW-MRI was performed prior to and on days 1, 3 and 5 during treatment. Assessment of tumour apoptosis and necrosis ex vivo was used to validate the imaging findings. Results: Both irinotecan and birinapant induced significant tumour growth delay. Irinotecan induced a small increase in the tumour apparent diffusion coefficient (ADC) after 1 day, with a 20 and 30% increase at days 3 and 5 respectively. ADC was unchanged in the vehicle- and birinapant-treated tumours despite a growth delay in the latter. Histological analysis showed that irinotecan increased necrosis at days 3 and 5, and induced apoptosis after 1 day, compared with vehicle. Birinapant induced apoptosis after day 3, but had no effect on tumour necrosis. Conclusions: Tumour ADC changes after irinotecan treatment were associated with the induction of a mixture of necrotic and apoptotic cell death, whereas induction of apoptosis alone with birinapant was not sufficient to induce changes in tissue microstructure that were detectable with DW-MRI. ADC is a useful non-invasive biomarker for early detection of response to cytotoxic drugs, but false negatives may arise while detecting apoptotic response to birinapant. PMID:25880014

  10. Diagnostic Utility of Diffusion-weighted Magnetic Resonance Imaging in Differentiating Small Solid Renal Tumors (≤4 cm) at 3.0T Magnetic Resonance Imaging

    PubMed Central

    Zhang, Han-Mei; Wu, Ying-Hua; Gan, Qi; Lyu, Xiao; Zhu, Xiang-Lan; Kuang, Min; Liu, Rong-Bo; Huang, Zi-Xing; Yuan, Fang; Liu, Xi-Jiao; Song, Bin

    2015-01-01

    Background: The aim of this study was to assess the performance of apparent diffusion coefficient (ADC) measurement obtained with diffusion-weighted magnetic resonance imaging (DW-MRI) to distinguish renal cell carcinomas (RCCs) from small benign solid renal tumors (≤4 cm). Methods: In this cross-sectional study, 49 consecutive patients with histopathologically confirmed small solid renal tumors, and seven healthy volunteers were imaged using nonenhanced MRI and DW-MRI. The ADC map was calculated using the b values of 0, 50, 400, and 600 s/mm2 and values compared via the Kruskal–Wallis and Mann–Whitney tests. The utility of ADC for differentiating RCCs and benign lesions was assessed using a receiver operating characteristic curve. Multiple nonenhanced MRI features were analyzed by Logistic regression. Results: The tumors consisted of 33 cases of clear-cell RCCs (ccRCCs) and 16 cases of benign tumors, including 14 cases of minimal fat angiomyolipomas and 2 cases of oncocytomas. The ADCs showed significant differences among benign tumors ([0.90 ± 0.52] × 10−3 mm2/s), ccRCCs ([1.53 ± 0.31] × 10−3 mm2/s) and the normal renal parenchyma ([2.22 ± 0.12] × 10−3 mm2/s) (P < 0.001). Moreover, there was statistically significant difference between high and low-grade ccRCCs (P = 0.004). Using a cut-off ADC of 1.36 × 10−3 mm2/s, DW-MRI resulted in an area under the curve (AUC), sensitivity, and specificity equal to 0.839, 75.8%, and 87.5%, respectively. Nonenhanced MRI alone and the combination of imaging methods led to an AUC, sensitivity and specificity equal to 0.919, 93.9%, and 81.2%, 0.998, 97%, and 100%, respectively. The Logistic regression showed that the location of the center of the tumor (inside the contour of the kidney) and appearance of stiff blood vessel were significantly helpful for diagnosing ccRCCs. Conclusions: DW-MRI has potential in distinguishing ccRCCs from benign lesions in human small solid renal tumors (≤4 cm), and in

  11. Value of Diffusion-Weighted Magnetic Resonance Imaging for Prediction and Early Assessment of Response to Neoadjuvant Radiochemotherapy in Rectal Cancer: Preliminary Results

    SciTech Connect

    Lambrecht, Maarten; Vandecaveye, Vincent; De Keyzer, Frederik; Roels, Sarah; Penninckx, Freddy; Van Cutsem, Eric; Filip, Claus; Haustermans, Karin

    2012-02-01

    Purpose: To evaluate diffusion-weighted magnetic resonance imaging (DWI) for response prediction before and response assessment during and early after preoperative radiochemotherapy (RCT) for locally advanced rectal cancer (LARC). Methods and Materials: Twenty patients receiving RCT for LARC underwent MRI including DWI before RCT, after 10-15 fractions and 1 to 2 weeks before surgery. Tumor volume and apparent diffusion coefficient (ADC; b-values: 0-1000 s/mm{sup 2}) were determined at all time points. Pretreatment tumor ADC and volume, tumor ADC change ( Increment ADC), and volume change ( Increment V) between pretreatment and follow-up examinations were compared with histopathologic findings after total mesorectal excision (pathologic complete response [pCR] vs. no pCR, ypT0-2 vs. ypT3-4, T-downstaging or not). The discriminatory capability of pretreatment tumor ADC and volume, Increment ADC, and Increment V for the detection of pCR was compared with receiver operating characteristics analysis. Results: Pretreatment ADC was significantly lower in patients with pCR compared with patients without (in mm{sup 2}/s: 0.94 {+-} 0.12 Multiplication-Sign 10{sup -3} vs. 1.19 {+-} 0.22 Multiplication-Sign 10{sup -3}, p = 0.003), yielding a sensitivity of 100% and specificity of 86% for detection of pCR. The volume reduction during and after RCT was significantly higher in patients with pCR compared with patients without (in %: {Delta}V{sub during}: -62 {+-} 16 vs. -33 {+-} 16, respectively, p = 0.015; and {Delta}V{sub post}: -86 {+-} 12 vs. -60 {+-} 21, p = 0.012), yielding a sensitivity of 83% and specificity of 71% for the {Delta}V{sub during} and, respectively, 83% and 86% for the {Delta}V{sub post}. The Increment ADC during ({Delta}ADC{sub during}) and after RCT ({Delta}ADC{sub post}) showed a significantly higher value in patients with pCR compared with patients without (in %: {Delta}ADC{sub during}: 72 {+-} 14 vs. 16 {+-} 12, p = 0.0006; and {Delta}ADC{sub post}: 88

  12. Demonstration of Non-Gaussian Restricted Diffusion in Tumor Cells Using Diffusion Time-Dependent Diffusion-Weighted Magnetic Resonance Imaging Contrast.

    PubMed

    Hope, Tuva R; White, Nathan S; Kuperman, Joshua; Chao, Ying; Yamin, Ghiam; Bartch, Hauke; Schenker-Ahmed, Natalie M; Rakow-Penner, Rebecca; Bussell, Robert; Nomura, Natsuko; Kesari, Santosh; Bjørnerud, Atle; Dale, Anders M

    2016-01-01

    The diffusion-weighted magnetic resonance imaging (DWI) technique enables quantification of water mobility for probing microstructural properties of biological tissue and has become an effective tool for collecting information about the underlying pathology of cancerous tissue. Measurements using multiple b-values have indicated biexponential signal attenuation, ascribed to "fast" (high ADC) and "slow" (low ADC) diffusion components. In this empirical study, we investigate the properties of the diffusion time (Δ)-dependent components of the diffusion-weighted (DW) signal in a constant b-value experiment. A xenograft gliobastoma mouse was imaged using Δ = 11 ms, 20 ms, 40 ms, 60 ms, and b = 500-4000 s/mm(2) in intervals of 500 s/mm(2). Data were corrected for EPI distortions, and the Δ-dependence on the DW-signal was measured within three regions of interest [intermediate- and high-density tumor regions and normal-appearing brain (NAB) tissue regions]. In this study, we verify the assumption that the slow decaying component of the DW-signal is non-Gaussian and dependent on Δ, consistent with restricted diffusion of the intracellular space. As the DW-signal is a function of Δ and is specific to restricted diffusion, manipulating Δ at constant b-value (cb) provides a complementary and direct approach for separating the restricted from the hindered diffusion component. We found that Δ-dependence is specific to the tumor tissue signal. Based on an extended biexponential model, we verified the interpretation of the diffusion time-dependent contrast and successfully estimated the intracellular restricted ADC, signal volume fraction, and cell size within each ROI. PMID:27532028

  13. Demonstration of Non-Gaussian Restricted Diffusion in Tumor Cells Using Diffusion Time-Dependent Diffusion-Weighted Magnetic Resonance Imaging Contrast

    PubMed Central

    Hope, Tuva R.; White, Nathan S.; Kuperman, Joshua; Chao, Ying; Yamin, Ghiam; Bartch, Hauke; Schenker-Ahmed, Natalie M.; Rakow-Penner, Rebecca; Bussell, Robert; Nomura, Natsuko; Kesari, Santosh; Bjørnerud, Atle; Dale, Anders M.

    2016-01-01

    The diffusion-weighted magnetic resonance imaging (DWI) technique enables quantification of water mobility for probing microstructural properties of biological tissue and has become an effective tool for collecting information about the underlying pathology of cancerous tissue. Measurements using multiple b-values have indicated biexponential signal attenuation, ascribed to “fast” (high ADC) and “slow” (low ADC) diffusion components. In this empirical study, we investigate the properties of the diffusion time (Δ)-dependent components of the diffusion-weighted (DW) signal in a constant b-value experiment. A xenograft gliobastoma mouse was imaged using Δ = 11 ms, 20 ms, 40 ms, 60 ms, and b = 500–4000 s/mm2 in intervals of 500 s/mm2. Data were corrected for EPI distortions, and the Δ-dependence on the DW-signal was measured within three regions of interest [intermediate- and high-density tumor regions and normal-appearing brain (NAB) tissue regions]. In this study, we verify the assumption that the slow decaying component of the DW-signal is non-Gaussian and dependent on Δ, consistent with restricted diffusion of the intracellular space. As the DW-signal is a function of Δ and is specific to restricted diffusion, manipulating Δ at constant b-value (cb) provides a complementary and direct approach for separating the restricted from the hindered diffusion component. We found that Δ-dependence is specific to the tumor tissue signal. Based on an extended biexponential model, we verified the interpretation of the diffusion time-dependent contrast and successfully estimated the intracellular restricted ADC, signal volume fraction, and cell size within each ROI. PMID:27532028

  14. Extrapolation-Based References Improve Motion and Eddy-Current Correction of High B-Value DWI Data: Application in Parkinson’s Disease Dementia

    PubMed Central

    Nilsson, Markus; Szczepankiewicz, Filip; van Westen, Danielle; Hansson, Oskar

    2015-01-01

    Purpose Conventional motion and eddy-current correction, where each diffusion-weighted volume is registered to a non diffusion-weighted reference, suffers from poor accuracy for high b-value data. An alternative approach is to extrapolate reference volumes from low b-value data. We aim to compare the performance of conventional and extrapolation-based correction of diffusional kurtosis imaging (DKI) data, and to demonstrate the impact of the correction approach on group comparison studies. Methods DKI was performed in patients with Parkinson’s disease dementia (PDD), and healthy age-matched controls, using b-values of up to 2750 s/mm2. The accuracy of conventional and extrapolation-based correction methods was investigated. Parameters from DTI and DKI were compared between patients and controls in the cingulum and the anterior thalamic projection tract. Results Conventional correction resulted in systematic registration errors for high b-value data. The extrapolation-based methods did not exhibit such errors, yielding more accurate tractography and up to 50% lower standard deviation in DKI metrics. Statistically significant differences were found between patients and controls when using the extrapolation-based motion correction that were not detected when using the conventional method. Conclusion We recommend that conventional motion and eddy-current correction should be abandoned for high b-value data in favour of more accurate methods using extrapolation-based references. PMID:26528541

  15. Diffusion-weighted images (DWI) without ADC values in assessment of small focal nodules in cirrhotic liver

    PubMed Central

    Chen, Mai-Lin; Zhang, Xiao-Yan; Qi, Li-Ping; Shi, Qing-Lei; Chen, Bin

    2014-01-01

    Objective To assess if diffusion-weighted magnetic resonance (MR) imaging without apparent diffusion coefficient (ADC) values provides added diagnostic value in combination with conventional MR imaging in the detection and characterization of small nodules in cirrhotic liver. Methods Two observers retrospectively and independently analyzed 86 nodules (≤3 cm) certified pathologically in 33 patients with liver cirrhosis, including 48 hepatocellular carcinoma (HCC) nodules, 13 high-grade dysplastic nodules (HDN), 10 low-grade dysplastic nodules (LDNs) and 15 other benign nodules. All these focal nodules were evaluated with conventional MR images (T1-weighted, T2-weighted and dynamic gadolinium-enhanced images) and breath-hold diffusion-weighted images (DWI) (b=500 s/mm2). The nodules were classified by using a scale of 1-3 (1, not seen; 3, well seen) on DWI for qualitative assessment. These small nodules were characterized by two radiologists. ADC values weren’t measured. The diagnostic performance of the combined DWI-conventional images and the conventional images alone was evaluated using receiver operating characteristic (ROC) curves. The area under the curves (Az), sensitivity and specificity values for characterizing different small nodules were also calculated. Results Among 48 HCC nodules, 33 (68.8%) were graded as 3 (well seen), 6 (12.5%) were graded as 2 (partially obscured), and 9 weren’t seen on DWI. Among 13 HDNs, there were 3 (23.1%) and 4 (30.8%) graded as 3 and 2 respectively. Five (50%) of 10 benign nodules were partially obscured and slightly hyperintense. For 86 nodules, the average diagnostic accuracy of combined DWI-conventional images was 82.56%, which was increased significantly compared with conventional MR images with 76.17%. For HCC and HDN, the diagnostic accuracy of combined DWI-conventional images increased from 78.69% to 86.07%. Conclusions Diffusion-weighted MR imaging does provide added diagnostic value in the detection and

  16. Intra-Individual, Inter-Vendor Comparison of Diffusion-Weighted MR Imaging of Upper Abdominal Organs at 3.0 Tesla with an Emphasis on the Value of Normalization with the Spleen

    PubMed Central

    Hwang, Seung Bae; Chung, Gyung Ho; Jin, Gong Yong

    2016-01-01

    Objective To compare the apparent diffusion coefficient (ADC) values of upper abdominal organs with 2 different 3.0 tesla MR systems and to investigate the usefulness of normalization using the spleen. Materials and Methods Forty-one patients were enrolled in this prospective study, of which, 35 patients (M:F, 27:8; mean age ± standard deviation, 62.3 ± 12.3 years) were finally analyzed. In addition to the routine liver MR protocol, single-shot spin-echo echo-planar diffusion-weighted imaging using b values of 0, 50, 400, and 800 s/mm2 in 2 different MR systems was performed. ADC values of the liver, spleen, pancreas, kidney and liver lesion (if present) were measured and analyzed. ADC values of the spleen were used for normalization. The Pearson correlation, Spearman correlation, paired sample t test, Wilcoxon signed rank test and Bland-Altman method were used for statistical analysis. Results For all anatomical regions and liver lesions, both non-normalized and normalized ADC values from 2 different MR systems showed significant correlations (r = 0.5196–0.8488). Non-normalized ADC values of both MR systems differed significantly in all anatomical regions and liver lesions (p < 0.001). However, the normalized ADC of all anatomical regions and liver lesions did not differ significantly (p = 0.065–0.661), with significantly lower coefficient of variance than that of non-normalized ADC (p < 0.009). Conclusion Normalization of the abdominal ADC values using the spleen as a reference organ reduces differences between different MR systems, and could facilitate consistent use of ADC as an imaging biomarker for multi-center or longitudinal studies. PMID:26957905

  17. Efficacy of HGF carried by ultrasound microbubble-cationic nano-liposomes complex for treating hepatic fibrosis in a bile duct ligation rat model, and its relationship with the diffusion-weighted MRI parameters.

    PubMed

    Zhang, Shou-hong; Wen, Kun-ming; Wu, Wei; Li, Wen-yan; Zhao, Jian-nong

    2013-12-01

    Hepatic fibrosis is a major consequence of liver aggression. Finding novel ways for counteracting this damaging process, and for evaluating fibrosis with a non-invasive imaging approach, represent important therapeutic and diagnostic challenges. Hepatocyte growth factor (HGF) is an anti-fibrosis cell growth factor that induces apoptosis in activated hepatic stellate cells, reduces excessive collagen deposition, and stimulates hepatocyte regeneration. Thus, using HGF in gene therapy against liver fibrosis is an attractive approach. The aims of the present study were: (i) to explore the efficacy of treating liver fibrosis using HGF expression vector carried by a novel ultrasound microbubble delivery system; (ii) to explore the diagnostic interest of diffusion-weighted MRI (DWI-MRI) in evaluating liver fibrosis. We established a rat model of hepatic fibrosis. The rats were administered HGF linked to novel ultrasound micro-bubbles. Progression of hepatic fibrosis was evaluated by histopathology, hydroxyproline content, and DWI-MRI to determine the apparent diffusion coefficient (ADC). Our targeted gene therapy produced a significant anti-fibrosis effect, as shown by liver histology and significant reduction of hydroxyproline content. Moreover, using DWI-MRI, the b value (diffusion gradient factor) was equal to 300s/mm(2), and the ADC values significantly decreased as the severity of hepatic fibrosis increased. Using this methodology, F0-F2 could be distinguished from F3 and F4 (P<0.01). This is the first in vivo report of using an ultrasound microbubble-cationic nano-liposome complex for gene delivery. The data indicate that, this approach is efficient to counteract the fibrosis process. DWI-MRI appears a promising imaging technique for evaluating liver fibrosis. PMID:24012221

  18. Clear Depiction of Inflammatory Abdominal Aortic Aneurysm with Diffusion-Weighted Magnetic Resonance Imaging

    SciTech Connect

    Orta Kilickesmez, Kadriye; Kilickesmez, Ozgur

    2010-04-15

    We report the case of an inflammatory abdominal aortic aneurysm incidentally detected clearly with diffusion-weighted magnetic resonance imaging (DW-MRI) during the examination of a patient with myelofibrosis with myeloid metaplasia that later converted to acute myeloid leukemia. DW-MRI revealed a hyperintense halo surrounding the abdominal aorta with aneurysmatic dilatation, establishing the diagnosis.

  19. Tensor Based Representation and Analysis of Diffusion-Weighted Magnetic Resonance Images

    ERIC Educational Resources Information Center

    Barmpoutis, Angelos

    2009-01-01

    Cartesian tensor bases have been widely used to model spherical functions. In medical imaging, tensors of various orders can approximate the diffusivity function at each voxel of a diffusion-weighted MRI data set. This approximation produces tensor-valued datasets that contain information about the underlying local structure of the scanned tissue.…

  20. MR elastography and diffusion-weighted imaging of ex vivo prostate cancer: quantitative comparison to histopathology.

    PubMed

    Sahebjavaher, Ramin S; Nir, Guy; Gagnon, Louis O; Ischia, Joseph; Jones, Edward C; Chang, Silvia D; Yung, Andrew; Honarvar, Mohammad; Fazli, Ladan; Goldenberg, S Larry; Rohling, Robert; Sinkus, Ralph; Kozlowski, Piotr; Salcudean, Septimiu E

    2015-01-01

    The purpose of this work was (1) to develop a magnetic resonance elastography (MRE) system for imaging of the ex vivo human prostate and (2) to assess the diagnostic power of mono-frequency and multi-frequency MRE and diffusion weighted imaging (DWI) alone and combined as correlated with histopathology in a patient study. An electromagnetic driver was designed specifically for MRE studies in small-bore MR scanners. Ex vivo prostate specimens (post-fixation) of 14 patients who underwent radical prostatectomy were imaged with MRE at 7 T (nine cases had DWI). In six patients, the MRE examination was performed at three frequencies (600, 800, 1000 Hz) to extract the power-law exponent Gamma. The images were registered to wholemount pathology slides marked with the Gleason score. The areas under the receiver-operator-characteristic curves (AUC) were calculated. The methods were validated in a phantom study and it was demonstrated that (i) the driver does not interfere with the acquisition process and (ii) the driver can generate amplitudes greater than 100 µm for frequencies less than 1 kHz. In the quantitative study, cancerous tissue with Gleason score at least 3 + 3 was distinguished from normal tissue in the peripheral zone (PZ) with an average AUC of 0.75 (Gd ), 0.75 (Gl ), 0.70 (Gamma-Gd ), 0.68 (apparent diffusion coefficient, ADC), and 0.82 (Gd  + Gl  + ADC). The differentiation between PZ and central gland was modest for Gd (p < 0.07), Gl (p < 0.06) but not significant for Gamma (p < 0.2). A correlation of 0.4 kPa/h was found between the fixation time of the prostate specimen and the stiffness of the tissue, which could affect the diagnostic power results. DWI and MRE may provide complementary information; in fact MRE performed better than ADC in distinguishing normal from cancerous tissue in some cases. Multi-frequency (Gamma) analysis did not appear to improve the results. However, in light of the effect of tissue fixation, the

  1. Integrative analysis of diffusion-weighted MRI and genomic data to inform treatment of glioblastoma.

    PubMed

    Jajamovich, Guido H; Valiathan, Chandni R; Cristescu, Razvan; Somayajula, Sangeetha

    2016-09-01

    Gene expression profiling from glioblastoma (GBM) patients enables characterization of cancer into subtypes that can be predictive of response to therapy. An integrative analysis of imaging and gene expression data can potentially be used to obtain novel biomarkers that are closely associated with the genetic subtype and gene signatures and thus provide a noninvasive approach to stratify GBM patients. In this retrospective study, we analyzed the expression of 12,042 genes for 558 patients from The Cancer Genome Atlas (TCGA). Among these patients, 50 patients had magnetic resonance imaging (MRI) studies including diffusion weighted (DW) MRI in The Cancer Imaging Archive (TCIA). We identified the contrast enhancing region of the tumors using the pre- and post-contrast T1-weighted MRI images and computed the apparent diffusion coefficient (ADC) histograms from the DW-MRI images. Using the gene expression data, we classified patients into four molecular subtypes, determined the number and composition of genes modules using the gap statistic, and computed gene signature scores. We used logistic regression to find significant predictors of GBM subtypes. We compared the predictors for different subtypes using Mann-Whitney U tests. We assessed detection power using area under the receiver operating characteristic (ROC) analysis. We computed Spearman correlations to determine the associations between ADC and each of the gene signatures. We performed gene enrichment analysis using Ingenuity Pathway Analysis (IPA). We adjusted all p values using the Benjamini and Hochberg method. The mean ADC was a significant predictor for the neural subtype. Neural tumors had a significantly lower mean ADC compared to non-neural tumors ([Formula: see text]), with mean ADC of [Formula: see text] and [Formula: see text] for neural and non-neural tumors, respectively. Mean ADC showed an area under the ROC of 0.75 for detecting neural tumors. We found eight gene modules in the GBM cohort. The

  2. Role of diffusion-weighted magnetic resonance imaging in differentiating malignancies from benign ovarian tumors

    PubMed Central

    Fan, Xinhua; Zhang, Hongbin; Meng, Shuang; Zhang, Jing; Zhang, Chuge

    2015-01-01

    Objective: We conducted a case-control study to evaluate the diagnostic values of computed tomography (CT) and diffusion-weighted magnetic resonance imaging (DW-MRI) in differentiating malignancies from benign ovarian tumors and a meta-analysis to further confirm our results on DW-MRI. Methods: Totally 64 patients pathologically confirmed as ovarian cancer were included in this study. CT scan and DWI-MRI were performed and analyzed to get compared with pathological results, thereby assessing their accuracy, sensitivity and specificity. Meta-analysis was conducted by database searching and strict eligibility criteria, using STATA 12.0 (Stata Corp, College Station, TX, USA) software. Results: The accuracy, sensitivity, specificity, positive predictive value and negative predictive value for diagnosis of ovarian cancer in CT were 81.82%, 84.48%, 76.67%, 87.50% and 71.88%, respectively; those in DW-MRI were 89.77%, 93.10%, 83.33%, 91.53% and 86.21%, respectively. The Kappa coefficient of DW-MRI (K = 0.771) compared with pathological results was higher than CT (K = 0.602). The average apparent diffusion coefficient values of DW-MRI in diagnosis of benign and malignant ovarian tumors suggested statistically significant difference (1.325 ± 0.269×10-3 mm2/s vs. 0.878 ± 0.246×10-3 mm2/s, P < 0.001). Meta-analysis results showed that the combined sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio of DW-MRI in discriminating benign versus malignant ovarian tumors were 0.93, 0.88, 7.70, 0.08 and 101.24, respectively. The area under the summary receiver operating characteristic curve was 0.95. Conclusions: Both CT and DW-MRI were of great diagnostic value in differentiating malignancies from benign ovarian tumors, while DW-MRI was superior to CT with higher accuracy, sensitivity and specificity. PMID:26884905

  3. Diffusion weighted imaging and diffusion tensor imaging in the evaluation of transplanted kidneys

    PubMed Central

    Palmucci, Stefano; Cappello, Giuseppina; Attinà, Giancarlo; Foti, Pietro Valerio; Siverino, Rita Olivia Anna; Roccasalva, Federica; Piccoli, Marina; Sinagra, Nunziata; Milone, Pietro; Veroux, Massimiliano; Ettorre, Giovanni Carlo

    2015-01-01

    Objective The aim of this study is to investigate the relation between renal indexes and functional MRI in a population of kidney transplant recipients who underwent MR with diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) of the transplanted graft. Method Study population included 40 patients with single kidney transplant. The patients were divided into 3 groups, on the basis of creatinine clearance (CrCl) values calculated using Cockcroft-Gault formula: group A, including patients with normal renal function (CrCl ≥ 60 mL/min); group B, which refers to patients with moderate renal impairment (CrCl > 30 but <60 mL/min); and, finally, group C, which means severe renal deterioration (CrCl ≤ 30 mL/min). All patients were investigated with a 1.5 Tesla MRI scanner, acquiring DWI and DTI sequences. A Mann–Whitney U test was adopted to compare apparent diffusion coefficients (ADCs) and fractional anisotropy (FA) measurements between groups. Receiver operating characteristic (ROC) curves were created for prediction of normal renal function (group A) and renal failure (group C). Pearson correlation was performed between renal clearance and functional imaging parameter (ADC and FA), obtained for cortical and medullar regions. Results Mann–Whitney U test revealed a highly significant difference (p < 0.01) between patients with low CrCl (group C) and normal CrCl (group A) considering both medullar ADC and FA and cortical ADC. Regarding contiguous groups, the difference between group B and C was highly significant (p < 0.01) for medullar ADC and significant (p < 0.05) for cortical ADC and medullar FA. No difference between these groups was found considering cortical FA. Analyzing groups A and B, we found a significant difference (p < 0.05) for medullar both ADC and FA, while no difference was found for cortical ADC and FA. Strongest Pearson correlation was found between CrCl and medullar ADC (r = 0.65). For predicting normal renal

  4. Improve the image quality of orbital 3 T diffusion-weighted magnetic resonance imaging with readout-segmented echo-planar imaging.

    PubMed

    Xu, Xiao-Quan; Liu, Jun; Hu, Hao; Su, Guo-Yi; Zhang, Yu-Dong; Shi, Hai-Bin; Wu, Fei-Yun

    2016-01-01

    The aim of our study is to compare the image quality of readout-segmented echo-planar imaging (rs-EPI) and that of standard single-shot EPI (ss-EPI) in orbital 3 T diffusion-weighted (DW) magnetic resonance (MR) imaging in healthy subjects. Forty-two volunteers underwent two sets of orbital DW imaging scan at a 3 T MR unit, and image quality was assessed qualitatively and quantitatively. As a result, we found that rs-EPI could provide better image quality than standard ss-EPI, while no significant difference was found on the apparent diffusion coefficient between the two sets of DW images. PMID:27317226

  5. Improving the Correction of Eddy Current-Induced Distortion in Diffusion-Weighted Images by Excluding Signals from the Cerebral Spinal Fluid

    PubMed Central

    Liu, Wei; Liu, Xiaozheng; Yang, Guang; Zhou, Zhenyu; Zhou, Yongdi; Li, Gengying; Dubin, Marc; Bansal, Ravi; Peterson, Bradley. S.; Xu, Dongrong

    2012-01-01

    Iterative Cross-Correlation (ICC) is the most popularly used schema for correcting eddy current (EC)-induced distortion in diffusion-weighted imaging data, however, it cannot process data acquired at high b-values. We analyzed the error sources and affecting factors in parameter estimation, and propose an efficient algorithm by expanding the ICC framework with a number of techniques: (1) Pattern recognition for excluding brain ventricles; (2) ICC with the extracted ventricle for parameter initialization; (3) Gradient-based Entropy Correlation Coefficient (GECC) for optimal and finer registration. Experiments demonstrated that our method is robust with high accuracy and error tolerance, and outperforms other ICC-family algorithms and popular approaches currently in use. PMID:22835646

  6. Pitfalls and Limitations of Diffusion-Weighted Magnetic Resonance Imaging in the Diagnosis of Urinary Bladder Cancer

    PubMed Central

    Lin, Wei-Ching; Chen, Jeon-Hor

    2015-01-01

    Adequately selecting a therapeutic approach for bladder cancer depends on accurate grading and staging. Substantial inaccuracy of clinical staging with bimanual examination, cystoscopy, and transurethral resection of bladder tumor has facilitated the increasing utility of magnetic resonance imaging to evaluate bladder cancer. Diffusion-weighted imaging (DWI) is a noninvasive functional magnetic resonance imaging technique. The high tissue contrast between cancers and surrounding tissues on DWI is derived from the difference of water molecules motion. DWI is potentially a useful tool for the detection, characterization, and staging of bladder cancers; it can also monitor posttreatment response and provide information on predicting tumor biophysical behaviors. Despite advancements in DWI techniques and the use of quantitative analysis to evaluate the apparent diffusion coefficient values, there are some inherent limitations in DWI interpretation related to relatively poor spatial resolution, lack of cancer specificity, and lack of standardized image acquisition protocols and data analysis procedures that restrict the application of DWI and reproducibility of apparent diffusion coefficient values. In addition, inadequate bladder distension, artifacts, thinness of bladder wall, cancerous mimickers of normal bladder wall and benign lesions, and variations in the manifestation of bladder cancer may interfere with diagnosis and monitoring of treatment. Recognition of these pitfalls and limitations can minimize their impact on image interpretation, and carefully applying the analyzed results and combining with pathologic grading and staging to clinical practice can contribute to the selection of an adequate treatment method to improve patient care. PMID:26055180

  7. Heidenhain variant of Creutzfeldt-Jakob disease: diffusion-weighted MRI and PET characteristics.

    PubMed

    Tsuji, Yoshihisa; Kanamori, Hiroshi; Murakami, Gaku; Yokode, Masayuki; Mezaki, Takahiro; Doh-ura, Katsumi; Taniguchi, Ken; Matsubayashi, Kozo; Fukuyama, Hidenao; Kita, Toru; Tanaka, Makoto

    2004-01-01

    Creutzfeldt-Jakob disease (CJD) is characterized by rapidly progressive dementia with a variety of neurological disorders and a fatal outcome. The authors present a case with visual disturbance as a leading symptom and rapid deterioration in global cognitive functions. The cerebrospinal fluid was positive for 14-3-3 protein, and diffusion-weighted magnetic resonance imaging (MRI) showed marked hyperintensity in the parieto-occipital cortices, where hypometabolism was clearly detected on positron emission tomography (PET). Pattern-reversal visual evoked potentials showed prolonged P100 latencies and increased N/5/P100 amplitudes. All these findings supported a diagnosis of the Heidenhain variant of CJD, whereas a long clinical course, a lack of myoclonus, and an absence of periodic synchronous discharges on electroencephalography were atypical. Diffusion-weighted MRI and PE1 in combination with visual evoked potential recording and 14-3-3 protein detection may be useful for the early diagnosis of CJD. PMID:14748211

  8. COMPARISON OF THE COMPLETE FOURIER DIRECT MRI WITH EXISTING DIFFUSION WEIGHTED MRI METHODS

    PubMed Central

    Özcan, Alpay

    2011-01-01

    The Complete Fourier Direct (CFD) MRI method introduced in earlier work for modeling the diffusion weighted MRI signal is compared with the existing methods. The preservation of Hermitian symmetry in the diffusion weighted MRI signal without affecting its energy is the key point that differentiates CFD–MRI from the existing methods. By keeping the correct Fourier relationship intact, the joint distribution function is represented ‘as it is’, without any constraints, e.g. being symmetric. The necessity to model or assume models for spin motion and try to fit the model to the samples of the Fourier transform as in case of model matching methods is not required because the Discrete Fourier Transform applied to correctly processed signal in CFD–MRI gives more accurate results. PMID:21918715

  9. Diffusion weighted imaging of female pelvic cancers: concepts and clinical applications.

    PubMed

    Punwani, Shonit

    2011-04-01

    Early applications of diffusion weighted magnetic resonance imaging (DWI) were limited to neuroimaging, concentrating either on stroke or brain tumours. With recent advances in MRI hardware and software DWI is now increasingly being investigated for cancer assessment throughout the body. Clinical applications of DWI relating to female pelvic cancers have largely concentrated on detection, localisation and staging of disease. More recently investigators have started to evaluate the ability of DWI for determining tumour histology and even predicting the outcome of chemoradiation treatment. This article reviews the physical concepts of MR diffusion weighting, illustrates the biophysical basis of diffusion contrast and reports the clinical applications of DWI for cervical, endometrial, ovarian, rectal and bladder tumours. PMID:20801592

  10. The design of anisotropic diffusion phantoms for the validation of diffusion weighted magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Fieremans, Els; DeDeene, Yves; Delputte, Steven; Özdemir, Mahir S.; Achten, Eric; Lemahieu, Ignace

    2008-10-01

    Diffusion weighted magnetic resonance imaging offers a non-invasive tool to explore the three-dimensional structure of brain white matter in clinical practice. Anisotropic diffusion hardware phantoms are useful for the quantitative validation of this technique. This study provides guidelines on how to manufacture anisotropic fibre phantoms in a reproducible way and which fibre material to choose to obtain a good quality of the diffusion weighted images. Several fibre materials are compared regarding their effect on the diffusion MR measurements of the water molecules inside the phantoms. The diffusion anisotropy influencing material properties are the fibre density and diameter, while the fibre surface relaxivity and magnetic susceptibility determine the signal-to-noise ratio. The effect on the T2-relaxation time of water in the phantoms has been modelled and the diffusion behaviour inside the fibre phantoms has been quantitatively evaluated using Monte Carlo random walk simulations.

  11. Diffeomorphic susceptibility artifact correction of diffusion-weighted magnetic resonance images.

    PubMed

    Ruthotto, L; Kugel, H; Olesch, J; Fischer, B; Modersitzki, J; Burger, M; Wolters, C H

    2012-09-21

    Diffusion-weighted magnetic resonance imaging is a key investigation technique in modern neuroscience. In clinical settings, diffusion-weighted imaging and its extension to diffusion tensor imaging (DTI) are usually performed applying the technique of echo-planar imaging (EPI). EPI is the commonly available ultrafast acquisition technique for single-shot acquisition with spatial encoding in a Cartesian system. A drawback of these sequences is their high sensitivity against small perturbations of the magnetic field, caused, e.g., by differences in magnetic susceptibility of soft tissue, bone and air. The resulting magnetic field inhomogeneities thus cause geometrical distortions and intensity modulations in diffusion-weighted images. This complicates the fusion with anatomical T1- or T2-weighted MR images obtained with conventional spin- or gradient-echo images and negligible distortion. In order to limit the degradation of diffusion-weighted MR data, we present here a variational approach based on a reference scan pair with reversed polarity of the phase- and frequency-encoding gradients and hence reversed distortion. The key novelty is a tailored nonlinear regularization functional to obtain smooth and diffeomorphic transformations. We incorporate the physical distortion model into a variational image registration framework and derive an accurate and fast correction algorithm. We evaluate the applicability of our approach to distorted DTI brain scans of six healthy volunteers. For all datasets, the automatic correction algorithm considerably reduced the image degradation. We show that, after correction, fusion with T1- or T2-weighted images can be obtained by a simple rigid registration. Furthermore, we demonstrate the improvement due to the novel regularization scheme. Most importantly, we show that it provides meaningful, i.e. diffeomorphic, geometric transformations, independent of the actual choice of the regularization parameters. PMID:22941943

  12. Non-oncologic applications of diffusion-weighted imaging (DWI) in the genitourinary system.

    PubMed

    Dunn, Dell P; Kelsey, Nathan R; Lee, Karen S; Smith, Martin P; Mortele, Koenraad J

    2015-08-01

    Diffusion-weighted imaging (DWI) has become an increasingly used tool in abdominal and pelvic magnetic resonance imaging (MRI), primarily in the oncologic setting. DWI sequences are being added to routine MRI protocols at many institutions, and as its use has spread, more non-oncologic applications have been explored. The purpose of this article is to provide a review of DWI applications in inflammatory, infectious, autoimmune-mediated, and ischemic processes affecting the genitourinary system. PMID:26109511

  13. X-PROP: a fast and robust diffusion-weighted propeller technique.

    PubMed

    Li, Zhiqiang; Pipe, James G; Lee, Chu-Yu; Debbins, Josef P; Karis, John P; Huo, Donglai

    2011-08-01

    Diffusion-weighted imaging (DWI) has shown great benefits in clinical MR exams. However, current DWI techniques have shortcomings of sensitivity to distortion or long scan times or combinations of the two. Diffusion-weighted echo-planar imaging (EPI) is fast but suffers from severe geometric distortion. Periodically rotated overlapping parallel lines with enhanced reconstruction diffusion-weighted imaging (PROPELLER DWI) is free of geometric distortion, but the scan time is usually long and imposes high Specific Absorption Rate (SAR) especially at high fields. TurboPROP was proposed to accelerate the scan by combining signal from gradient echoes, but the off-resonance artifacts from gradient echoes can still degrade the image quality. In this study, a new method called X-PROP is presented. Similar to TurboPROP, it uses gradient echoes to reduce the scan time. By separating the gradient and spin echoes into individual blades and removing the off-resonance phase, the off-resonance artifacts in X-PROP are minimized. Special reconstruction processes are applied on these blades to correct for the motion artifacts. In vivo results show its advantages over EPI, PROPELLER DWI, and TurboPROP techniques. PMID:21661046

  14. In Vivo Magnetization Transfer and Diffusion-Weighted Magnetic Resonance Imaging Detects Thrombus Composition in a Mouse Model of Deep Vein Thrombosis

    PubMed Central

    Saha, Prakash; Modarai, Bijan; Smith, Alberto; Botnar, René M.

    2014-01-01

    Background Deep vein thrombosis remains a major health problem necessitating accurate diagnosis. Thrombolysis is associated with significant morbidity and is effective only for the treatment of unorganized thrombus. We tested the feasibility of in vivo magnetization transfer (MT) and diffusion-weighted magnetic resonance imaging to detect thrombus organization in a murine model of deep vein thrombosis. Methods and Results Deep vein thrombosis was induced in the inferior vena cava of male BALB/C mice. Magnetic resonance imaging was performed at days 1, 7, 14, 21, and 28 after thrombus induction using MT, diffusion-weighted, inversion-recovery, and T1-mapping protocols. Delayed enhancement and T1 mapping were repeated 2 hours after injection of a fibrin contrast agent. Finally, excised thrombi were used for histology. We found that MT and diffusion-weighted imaging can detect histological changes associated with thrombus aging. MT rate (MTR) maps and percentage of MT rate (%MTR) allowed visualization and quantification of the thrombus protein content, respectively. The %MTR increased with thrombus organization and was significantly higher at days 14, 21, and 28 after thrombus induction (days 1, 7, 14, 21, 28: %MTR=2483±451, 2079±1210, 7029±2490, 10 295±4356, 32 994±25 449; Panova<0.05). There was a significant positive correlation between the %MTR and the histological protein content of the thrombus (r=0.70; P<0.05). The apparent diffusion coefficient was lower in erythrocyte-rich and collagen-rich thrombus (0.72±0.10 and 0.69±0.05 [×10−3 mm2/s]). Thrombus at days 7 and 14 had the highest apparent diffusion coefficient values (0.95±0.09 and 1.10±0.18 [×10−3 mm2/s]). Conclusions MT and diffusion-weighted magnetic resonance imaging sequences are promising for the staging of thrombus composition and could be useful in guiding medical intervention. PMID:23564561

  15. Diffusion Weighted MR Imaging of Breast and Correlation of Prognostic Factors in Breast Cancer

    PubMed Central

    Kızıldağ Yırgın, İnci; Arslan, Gözde; Öztürk, Enis; Yırgın, Hakan; Taşdemir, Nihat; Gemici, Ayşegül Akdoğan; Kabul, Fatma Çelik; Kaya, Eyüp

    2016-01-01

    Background: Through Diffusion Weighted Imaging (DWI), information related to early molecular changes, changes in the permeability of cell membranes, and early morphologic and physiologic changes such as cell swelling can be obtained. Aims: We investigated the correlation between the prognostic factors of breast cancer and apparent diffusion coefficient (ADC) in DWI sequences of malignant lesions. Study Design: Retrospective cross-sectional study. Methods: Patients who were referred to our clinic between September 2012 and September 2013, who underwent dynamic breast MRI before or after biopsy and whose biopsy results were determined as malignant, were included in our study. Before the dynamic analysis, DWI sequences were taken. ADC relationship with all prognostic factors was investigated. Pearson correlation test was used to compare the numerical data, while Spearman correlation and Fisher exact tests were used to compare the categorical data. The advanced relationships were evaluated with linear regression analysis and univariate analysis. The efficiency of the parameters was evaluated using ROC analysis. The significance level (P) was accepted as 0.05. Results: In total, 41 female patients with an average age of 49.4 years (age interval 21–77) and 44 lesions were included into the study. In the Pearson correlation test, no statistically significant difference was determined between ADC and the patient’s age and tumor size. In the Spearman correlation test, a statistically significant difference was determined between nuclear grade (NG) and ADC (r=−0.424, p=0.04); no statistically significant correlation was observed between the other prognostic factors with each other and ADC values. In the linear regression analysis, the relationship of NG with ADC was found to be more significant alone than when comparing all parameters (corrected r2=0.196, p=0.005). Further evaluations between the NG and ADC correlation were carried out with ROC analysis. A

  16. The diagnostic value of biexponential apparent diffusion coefficients in myopathy.

    PubMed

    Ran, Jun; Liu, Yao; Sun, Dong; Morelli, John; Zhang, Ping; Wu, Gang; Sheng, Yuda; Xie, Ruyi; Zhang, Xiaoli; Li, Xiaoming

    2016-07-01

    To investigate the performance of a biexponential signal decay model using DWI in myopathies and to differentiate Polymyositis (PM)/Dermatomyositis (DM), Glycogen Storage Diseases (GSDs) and Muscular Dystrophies (MDs) utilizing diffusion-weighted imaging. 11 healthy volunteers (control group) and 46 patients with myopathy were enrolled in the retrospective study. 27 of 46 patients had PM/DM, 7 patients GSDs and 12 patients MDs. After conventional MR sequences, diffusion weighted imaging with a b-factor ranging from 0 to 1200 s/mm(2) was performed on both thighs. The intra-muscular signal-to-noise ratios (SNRs) on multiple-b DWI images were measured for 7 different muscles and compared among the different groups. The median T2 signal intensity and biexponential apparent diffusion coefficients (ADC), including standard ADC, fast ADC, and slow ADC values, were compared among the different groups. The intra-muscular SNRs were statistically significantly different depending on the b value, and also found among the 4 groups (p < 0.05). The median T2 signal intensity of the normal muscles in control group was statistically significantly lower than that of edematous muscles in the PM/DM, GSDs and MDs groups (p = 0.000), while there were no statistically significant differences among the PM/DM, GSDs, and MDs groups (p > 0.05). The median standard ADC value of the edematous muscles in GSDs was statistically significantly lower than that of normal muscles in the control group (p = 0.000) and the median ADC value of the edematous muscles in PM/DM patients was statistically significantly greater than that of the GSDs (p = 0.000) and MDs groups (p = 0.005). The median slow ADC value of the edematous muscles in MDs patients and PM/DM patients was statistically significantly greater than that of GSDs patients (p < 0.05). Intra-muscular SNR decay curves and biexponential ADC parameters are useful in distinguishing among PM/DM, GSDs, and MDs. PMID:27142711

  17. Anisotropic diffusion of metabolites in peripheral nerve using diffusion weighted magnetic resonance spectroscopy at ultra-high field

    NASA Astrophysics Data System (ADS)

    Ellegood, Jacob; McKay, Ryan T.; Hanstock, Chris C.; Beaulieu, Christian

    2007-01-01

    Although the diffusivity and anisotropy of water has been investigated thoroughly in ordered axonal systems (i.e., nervous tissue), there have been very few studies on the directional dependence of diffusion of metabolites. In this study, the mean apparent diffusion coefficient (Trace/3 ADC) and fractional anisotropy (FA) values of the intracellular metabolites N-acetyl aspartate (NAA), creatine and phosphocreatine (tCr), choline (Cho), taurine (Tau), and glutamate and glutamine (Glx) were measured parallel and perpendicular to the length of excised frog sciatic nerve using a water suppressed, diffusion-weighted, spin-echo pulse sequence at 18.8 T. The degree of anisotropy (FA) of NAA (0.41 ± 0.09) was determined to be less than tCr (0.59 ± 0.07) and Cho (0.61 ± 0.11), which is consistent with previously reported human studies of white matter. In contrast, Glx diffusion was found to be almost isotropic with an FA value of 0.20 ± 0.06. The differences of FA between the metabolites is most likely due to their differing micro-environments and could be beneficial as an indicator of compartment specific changes with disease, information not readily available with water diffusion.

  18. Diffusion-weighted imaging-based probabilistic segmentation of high- and low-proliferative areas in high-grade gliomas

    PubMed Central

    Fritzsche, Klaus H.; Thieke, Christian; Klein, Jan; Parzer, Peter; Weber, Marc-André; Stieltjes, Bram

    2012-01-01

    Abstract The apparent diffusion coefficient (ADC) derived from diffusion-weighted imaging (DWI) correlates inversely with tumor proliferation rates. High-grade gliomas are typically heterogeneous and the delineation of areas of high and low proliferation is impeded by partial volume effects and blurred borders. Commonly used manual delineation is further impeded by potential overlap with cerebrospinal fluid and necrosis. Here we present an algorithm to reproducibly delineate and probabilistically quantify the ADC in areas of high and low proliferation in heterogeneous gliomas, resulting in a reproducible quantification in regions of tissue inhomogeneity. We used an expectation maximization (EM) clustering algorithm, applied on a Gaussian mixture model, consisting of pure superpositions of Gaussian distributions. Soundness and reproducibility of this approach were evaluated in 10 patients with glioma. High- and low-proliferating areas found using the clustering correspond well with conservative regions of interest drawn using all available imaging data. Systematic placement of model initialization seeds shows good reproducibility of the method. Moreover, we illustrate an automatic initialization approach that completely removes user-induced variability. In conclusion, we present a rapid, reproducible and automatic method to separate and quantify heterogeneous regions in gliomas. PMID:22487677

  19. Major mouse placental compartments revealed by diffusion-weighted MRI, contrast-enhanced MRI, and fluorescence imaging

    PubMed Central

    Solomon, Eddy; Avni, Reut; Hadas, Ron; Raz, Tal; Garbow, Joel Richard; Bendel, Peter; Frydman, Lucio; Neeman, Michal

    2014-01-01

    Mammalian models, and mouse studies in particular, play a central role in our understanding of placental development. Magnetic resonance imaging (MRI) could be a valuable tool to further these studies, providing both structural and functional information. As fluid dynamics throughout the placenta are driven by a variety of flow and diffusion processes, diffusion-weighted MRI could enhance our understanding of the exchange properties of maternal and fetal blood pools—and thereby of placental function. These studies, however, have so far been hindered by the small sizes, the unavoidable motions, and the challenging air/water/fat heterogeneities, associated with mouse placental environments. The present study demonstrates that emerging methods based on the spatiotemporal encoding (SPEN) of the MRI information can robustly overcome these obstacles. Using SPEN MRI in combination with albumin-based contrast agents, we analyzed the diffusion behavior of developing placentas in a cohort of mice. These studies successfully discriminated the maternal from the fetal blood flows; the two orders of magnitude differences measured in these fluids’ apparent diffusion coefficients suggest a nearly free diffusion behavior for the former and a strong flow-based component for the latter. An intermediate behavior was observed by these methods for a third compartment that, based on maternal albumin endocytosis, was associated with trophoblastic cells in the interphase labyrinth. Structural features associated with these dynamic measurements were consistent with independent intravital and ex vivo fluorescence microscopy studies and are discussed within the context of the anatomy of developing mouse placentas. PMID:24969421

  20. Major mouse placental compartments revealed by diffusion-weighted MRI, contrast-enhanced MRI, and fluorescence imaging.

    PubMed

    Solomon, Eddy; Avni, Reut; Hadas, Ron; Raz, Tal; Garbow, Joel Richard; Bendel, Peter; Frydman, Lucio; Neeman, Michal

    2014-07-15

    Mammalian models, and mouse studies in particular, play a central role in our understanding of placental development. Magnetic resonance imaging (MRI) could be a valuable tool to further these studies, providing both structural and functional information. As fluid dynamics throughout the placenta are driven by a variety of flow and diffusion processes, diffusion-weighted MRI could enhance our understanding of the exchange properties of maternal and fetal blood pools--and thereby of placental function. These studies, however, have so far been hindered by the small sizes, the unavoidable motions, and the challenging air/water/fat heterogeneities, associated with mouse placental environments. The present study demonstrates that emerging methods based on the spatiotemporal encoding (SPEN) of the MRI information can robustly overcome these obstacles. Using SPEN MRI in combination with albumin-based contrast agents, we analyzed the diffusion behavior of developing placentas in a cohort of mice. These studies successfully discriminated the maternal from the fetal blood flows; the two orders of magnitude differences measured in these fluids' apparent diffusion coefficients suggest a nearly free diffusion behavior for the former and a strong flow-based component for the latter. An intermediate behavior was observed by these methods for a third compartment that, based on maternal albumin endocytosis, was associated with trophoblastic cells in the interphase labyrinth. Structural features associated with these dynamic measurements were consistent with independent intravital and ex vivo fluorescence microscopy studies and are discussed within the context of the anatomy of developing mouse placentas. PMID:24969421

  1. Intraprocedural Diffusion-Weighted PROPELLER MRI to Guide Percutaneous Biopsy Needle Placement within Rabbit VX2 Liver Tumors

    PubMed Central

    Deng, Jie; Virmani, Sumeet; Yang, Guang-Yu; Tang, Richard; Woloschak, Gayle; Omary, Reed A.; Larson, Andrew C.

    2010-01-01

    Purpose To test the hypothesis that diffusion-weighted (DW)-PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) magnetic resonance imaging (MRI) can be used to guide biopsy needle placement during percutaneous interventional procedures to selectively target viable and necrotic tissues within VX2 rabbit liver tumors. Materials and Methods Our institutional Animal Care and Use Committee approved all experiments. In six rabbits implanted with 15 VX2 liver tumors, baseline DWPROPELLER images acquired prior to the interventional procedure were used for apparent diffusion coefficient (ADC) measurements. Next, intraprocedural DW-PROPELLER scans were performed with needle position iteratively adjusted to target viable, necrotic, or intermediate border tissue regions. DW-PROPELLER ADC measurements at the selected needle tip locations were compared with the percentage of tumor necrosis qualitatively assessed at histopathology. Results DW-PROPELLER images demonstrated intratumoral tissue heterogeneity and clearly depicted the needle tip position within viable and necrotic tumor tissues. Mean ADC measurements within the region-of-interest encompassing the needle tip were highly correlated with histopathologic tumor necrotic tissue assessments. Conclusion DW-PROPELLER is an effective method to selectively position the biopsy needle tip within viable and necrotic tumor tissues. The DW-PROPELLER method may offer an important complementary tool for functional guidance during MR-guided percutaneous procedures. PMID:19629976

  2. Molecular imaging of water binding state and diffusion in breast cancer using diffuse optical spectroscopy and diffusion weighted MRI

    PubMed Central

    Yu, Hon; Su, Min-Ying; Cerussi, Albert E.; Tromberg, Bruce J.

    2012-01-01

    Abstract. Tissue water content and molecular microenvironment can provide important intrinsic contrast for cancer imaging. In this work, we examine the relationship between water optical spectroscopic features related to binding state and magnetic resonance imaging (MRI)-measured water diffusion dynamics. Broadband diffuse optical spectroscopic imaging (DOSI) and MR images were obtained from eight patients with locally-advanced infiltrating ductal carcinomas (tumor size=5.5±3.2  cm). A DOSI-derived bound water index (BWI) was compared to the apparent diffusion coefficient (ADC) of diffusion weighted (DW) MRI. BWI and ADC were positively correlated (R=0.90, p-value=0.003) and BWI and ADC both decreased as the bulk water content increased (R=−0.81 and −0.89, respectively). BWI correlated inversely with tumor size (R=−0.85, p-value=0.008). Our results suggest underlying sensitivity differences between BWI and ADC to water in different tissue compartments (e.g., extracellular vs cellular). These data highlight the potential complementary role of DOSI and DW-MRI in providing detailed information on the molecular disposition of water in breast tumors. Because DOSI is a portable technology that can be used at the bedside, BWI may provide a low-cost measure of tissue water properties related to breast cancer biology. PMID:22894465

  3. Quantitative Evaluation of Growth Plates around the Knees of Adolescent Soccer Players by Diffusion-Weighted Magnetic Resonance Imaging

    PubMed Central

    Krajnc, Zmago; Rupreht, Mitja; Drobnič, Matej

    2015-01-01

    Purpose. To quantitatively evaluate growth plates around the knees in adolescent soccer players utilizing the diffusion-weighted MR imaging (DWI). Methods. The knees and adjacent growth plates of eleven 14-year-old male soccer players were evaluated by MRI before (end of season's summer break) and after two months of intense soccer training. MRI evaluation was conducted in coronal plane by PD-FSE and DWI. All images were screened for any major pathological changes. Later, central growth plate surface area (CGPSA) was measured and the apparent diffusion coefficient (ADC) values were calculated in two most central coronal slices divided into four regions: distal femur medial (DFM), distal femur lateral (DFL), proximal tibia medial (PTM), and proximal tibia lateral (PTL). Results. No gross pathology was diagnosed on MRI. CGPSA was not significantly reduced: DFM 278 versus 272, DFL 265 versus 261, PTM 193 versus 192, and PTL 214 versus 210. ADC decrease was statistically significant only for PTM: DFM 1.27 versus 1.22, DFL 1.37 versus 1.34, PTM 1.13 versus 1.03 (p = 0.003), and PTL 1.28 versus 1.22. Conclusions. DWI measurements indicate increased cellularity in growth plates around knees in footballers most prominent in PTM after intense training. No detectable differences on a standard PD-FSE sequence were observed. PMID:26693482

  4. Pretreatment Diffusion-Weighted MRI Can Predict the Response to Neoadjuvant Chemotherapy in Patients with Nasopharyngeal Carcinoma

    PubMed Central

    Zhang, Guo-Yi; Wang, Yue-Jian; Liu, Jian-Ping; Zhou, Xin-Han; Xu, Zhi-Feng; Chen, Xiang-Ping; Xu, Tao; Wei, Wei-Hong; Zhang, Yang; Huang, Ying

    2015-01-01

    Purpose. To explore the potential of diffusion-weighted (DW) magnetic resonance imaging (MRI) using apparent diffusion coefficient (ADC) for predicting the response to neoadjuvant chemotherapy in nasopharyngeal carcinoma (NPC). Methods and Materials. Ninety-two consecutive patients with NPC who underwent three cycles of neoadjuvant chemotherapy were retrospectively analyzed. DW and anatomical MRI were performed before and after neoadjuvant chemotherapy prior to radiotherapy. Pretreatment ADCs and percentage increases in ADC after chemotherapy were calculated for the primary lesions and metastatic adenopathies. Receiver operating characteristic curve analysis was used to select optimal pretreatment ADCs. Results. Pretreatment mean ADCs were significantly lower for responders than for nonresponders (primary lesions, P = 0.012; metastatic adenopathies, P = 0.013). Mean percentage increases in ADC were higher for responders than for nonresponders (primary lesions, P = 0.008; metastatic adenopathies, P < 0.001). The optimal pretreatment primary lesion and metastatic adenopathy ADCs for differentiating responders from nonresponders were 0.897 × 10−3 mm2/sec and 1.031 × 10−3 mm2/sec, respectively. Conclusions. NPC patients with low pretreatment ADCs tend to respond better to neoadjuvant chemotherapy. Pretreatment ADCs could be used as a new pretreatment imaging biomarker of response to neoadjuvant chemotherapy. PMID:26413513

  5. Intravoxel Incoherent Motion Diffusion Weighted Magnetic Resonance Imaging for Differentiation Between Nasopharyngeal Carcinoma and Lymphoma at the Primary Site

    PubMed Central

    Yu, Xiao-Ping; Hou, Jing; Li, Fei-Ping; Wang, Hui; Hu, Ping-Sheng; Bi, Feng; Wang, Wei

    2016-01-01

    Objective The aim of the study was to investigate the utility of intravoxel incoherent motion (IVIM) diffusion-weighted magnetic resonance imaging (DWI) for differentiating nasopharyngeal carcinoma (NPC) from lymphoma. Methods Intravoxel incoherent motion–based parameters including the apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudodiffusion coefficient (D*), perfusion fraction (f), and fD* (the product of D* and f) were retrospectively compared between 102 patients (82 with NPC, 20 with lymphoma) who received pretreatment IVIM DWI. Results Compared with lymphoma, NPC exhibited higher ADC, D, D*, fD* values (P < 0.001) and f value (P = 0.047). The optimal cutoff values (area under the curve, sensitivity, and specificity, respectively) for distinguishing the 2 tumors were as follows: ADC value of 0.761 × 10−3 mm2/s (0.781, 93.90%, 55.00%); D, 0.66 × 10−3 mm2/s (0.802, 54.88%, 100.00%); D*, 7.89 × 10−3 mm2/s (0.898, 82.93%, 85.00%); f, 0.29 (0.644, 41.46%, 95.00%); and fD*, 1.99 × 10−3 mm2/s (0.960, 85.37%, 100.00%). Conclusions Nasopharyngeal carcinoma exhibits different IVIM-based imaging features from lymphoma. Intravoxel incoherent motion DWI is useful for differentiating lymphoma from NPC. PMID:26953769

  6. The role of pre-treatment diffusion-weighted MRI in predicting long-term outcome of colorectal liver metastasis

    PubMed Central

    Collins, D J; Brown, G; Chau, I; Cunningham, D; Leach, M O; Koh, D-M

    2013-01-01

    Objective: To determine the prognostic value of pre-treatment apparent diffusion coefficient (ADC) of colorectal liver metastases in predicting disease response, progression-free survival (PFS) and overall survival (OS). Methods: We retrospectively reviewed 102 patients who underwent pre-treatment diffusion-weighted MRI using a breath-hold (b=0, 150, 500) or a free-breathing (b=0, 50, 100, 250, 500, 750) technique. The mean ADC (b=0–500) and mean flow-insensitive ADC (ADChigh) values (breath-hold: b=150 and 500; free-breathing: b=100 and 500) of up to three hepatic lesions were evaluated in each patient. Clinical and laboratory parameters were recorded. Tumour response was assessed by Response Evaluation Criteria in Solid Tumors (RECIST) criteria at 12 weeks after treatment. Associations between tumour response, ADC values and clinical/laboratory parameters were examined by one-way analysis of variance. The relationship of ADC with PFS and OS was determined by Kaplan–Meier analysis. Results: 62 patients responded to chemotherapy at 12 weeks. The pre-treatment mean ADC and mean ADChigh were higher in the non-responding group than in the responding group (1.55 vs 1.36, p=0.033; 1.40 vs 1.16, p=0.024). However, the PFS and OS of the two groups of patients stratified by the median of mean ADC values or threshold derived by receiver operating characteristic analysis were not statistically significant. By multivariate Cox regression analysis, patients with ≤2 metastases and response to chemotherapy showed better PFS; white cell count ≤10 and surgical treatment were associated with better OS. Conclusion: Colorectal liver metastasis with higher pre-treatment mean ADC and mean ADChigh was associated with poorer response to chemotherapy. However, ADC and ADChigh values did not predict the patient outcome in this study cohort. Advances in knowledge: High mean ADC values of colorectal liver metastases on pre-treatment diffusion-weighted MRI is associated with poorer

  7. Monitoring Early Response to Anti-Angiogenic Therapy: Diffusion-Weighted Magnetic Resonance Imaging and Volume Measurements in Colon Carcinoma Xenografts

    PubMed Central

    Schneider, Moritz Jörg; Cyran, Clemens Christian; Nikolaou, Konstantin; Hirner, Heidrun; Reiser, Maximilian F.; Dietrich, Olaf

    2014-01-01

    Objectives To evaluate the use of diffusion-weighted MRI (DW-MRI) and volume measurements for early monitoring of antiangiogenic therapy in an experimental tumor model. Materials and Methods 23 athymic nude rats, bearing human colon carcinoma xenografts (HT-29) were examined before and after 6 days of treatment with regorafenib (n = 12) or placebo (n = 11) in a clinical 3-Tesla MRI. For DW-MRI, a single-shot EPI sequence with 9 b-values (10–800 s/mm2) was used. The apparent diffusion coefficient (ADC) was calculated voxelwise and its median value over a region of interest, covering the entire tumor, was defined as the tumor ADC. Tumor volume was determined using T2-weighted images. ADC and volume changes between first and second measurement were evaluated as classifiers by a receiver-operator-characteristic (ROC) analysis individually and combined using Fisher's linear discriminant analysis (FLDA). Results All ADCs and volumes are stated as median±standard deviation. Tumor ADC increased significantly in the therapy group (0.76±0.09×10−3 mm2/s to 0.90±0.12×10−3 mm2/s; p<0.001), with significantly higher changes of tumor ADC than in the control group (0.10±0.11×10−3 mm2/s vs. 0.03±0.09×10−3 mm2/s; p = 0.027). Tumor volume increased significantly in both groups (therapy: 347.8±449.1 to 405.3±823.6 mm3; p = 0.034; control: 219.7±79.5 to 443.7±141.5 mm3; p<0.001), however, the therapy group showed significantly reduced tumor growth (33.30±47.30% vs. 96.43±31.66%; p<0.001). Area under the curve and accuracy of the ADC-based ROC analysis were 0.773 and 78.3%; and for the volume change 0.886 and 82.6%. The FLDA approach yielded an AUC of 0.985 and an accuracy of 95.7%. Conclusions Regorafenib therapy significantly increased tumor ADC after 6 days of treatment and also significantly reduced tumor growth. However, ROC analyses using each parameter individually revealed a lack of accuracy in discriminating between therapy and control

  8. Diffusion-weighted and diffusion tensor imaging of the brain, made easy.

    PubMed

    Huisman, T A G M

    2010-01-01

    Diffusion-weighted and diffusion tensor imaging (DWI/DTI) has revolutionized clinical neuroimaging. Pathology may be detected earlier and with greater specificity than with conventional magnetic resonance imaging sequences. In addition, DWI/DTI allows exploring the microarchitecture of the brain. A detailed knowledge of the basics of DWI/DTI is mandatory to better understand pathology encountered and to avoid misinterpretation of typical DWI/DTI artifacts. This article reviews the basic physics of DWI/DTI exemplified by several classical clinical cases. PMID:20880787

  9. The expanding landscape of diffusion-weighted MRI in prostate cancer.

    PubMed

    Wibmer, Andreas G; Sala, Evis; Hricak, Hedvig; Vargas, Hebert Alberto

    2016-05-01

    The added value of diffusion-weighted magnetic resonance imaging (DW-MRI) for the detection, localization, and staging of primary prostate cancer has been extensively reported in original studies and meta-analyses. More recently, DW-MRI and related techniques have been used to noninvasively assess prostate cancer aggressiveness and estimate its biological behavior. The present article aims to summarize the potential applications of DW-MRI for noninvasive optimization of pretherapeutic risk assessment, patient management decisions, and evaluation of treatment response. PMID:26814501

  10. Diffusion-weighted MR imaging of the kidneys and the urinary tract.

    PubMed

    Kim, Sooah; Naik, Mohit; Sigmund, Eric; Taouli, Bachir

    2008-11-01

    There is currently a growing interest in applications of diffusion-weighted imaging (DWI) in the abdomen and pelvis. DWI provides original functional information where the signal and contrast are determined by the microscopic mobility of water. DWI can provide additional information over conventional MR sequences, and could potentially be used as an alternative to contrast-enhanced sequences in patients with chronic renal insufficiency at risk of nephrogenic systemic fibrosis. We provide an overview on basic physics background on DWI applied to the kidneys, and we summarize the current available data, including our recent experience. PMID:18926424

  11. Diffusion-weighted MR imaging findings of ovarian adenocarcinofibromas and adenofibromas.

    PubMed

    Kozawa, Eito; Inoue, Kaiji; takahashi, Masahiro; Kato, Tomomi; Yasuda, Masanori; Kimura, Fumiko

    2014-01-01

    We retrospectively evaluated pelvic magnetic resonance imaging including diffusion-weighted imaging (DWI) of 16 ovarian lesions (5 adenocarcinofibromas, 2 borderline adenofibromas, and 9 benign adenofibromas). All adenocarcinofibromas were detected as large solid areas of strong high signal on DWI, and seven of nine benign adenofibromas and both borderline adenofibromas demonstrated no areas of high signal or small areas of weak high signal. Solid components that appear as areas of strong high signal on DWI might represent a characteristic finding of adenocarcinofibromas. PMID:24685607

  12. Diffusion-Weighted Imaging Outside the Brain: Consensus Statement From an ISMRM-Sponsored Workshop

    PubMed Central

    Taouli, Bachir; Beer, Ambros J.; Chenevert, Thomas; Collins, David; Lehman, Constance; Matos, Celso; Padhani, Anwar R.; Rosenkrantz, Andrew B.; Shukla-Dave, Amita; Sigmund, Eric; Tanenbaum, Lawrence; Thoeny, Harriet; Thomassin-Naggara, Isabelle; Barbieri, Sebastiano; Corcuera-Solano, Idoia; Orton, Matthew; Partridge, Savannah C.; Koh, Dow-Mu

    2016-01-01

    The significant advances in magnetic resonance imaging (MRI) hardware and software, sequence design, and postprocessing methods have made diffusion-weighted imaging (DWI) an important part of body MRI protocols and have fueled extensive research on quantitative diffusion outside the brain, particularly in the oncologic setting. In this review, we summarize the most up-to-date information on DWI acquisition and clinical applications outside the brain, as discussed in an ISMRM-sponsored symposium held in April 2015. We first introduce recent advances in acquisition, processing, and quality control; then review scientific evidence in major organ systems; and finally describe future directions. PMID:26892827

  13. Quantitative Analysis of Diffusion Weighted MR Images of Brain Tumor Using Signal Intensity Gradient Technique

    PubMed Central

    Shanbhag, S. S.; Udupi, G. R.; Patil, K. M.; Ranganath, K.

    2014-01-01

    The purpose of this study was to evaluate the role of diffusion weighted-magnetic resonance imaging (DW-MRI) in the examination and classification of brain tumors, namely, glioma and meningioma. Our hypothesis was that as signal intensity variations on diffusion weighted (DW) images depend on histology and cellularity of the tumor, analysing the signal intensity characteristics on DW images may allow differentiating between the tumor types. Towards this end the signal intensity variations on DW images of the entire tumor volume data of 20 subjects with glioma and 12 subjects with meningioma were investigated and quantified using signal intensity gradient (SIG) parameter. The relative increase in the SIG values (RSIG) for the subjects with glioma and meningioma was in the range of 10.08–28.36 times and 5.60–9.86 times, respectively, compared to their corresponding SIG values on the contralateral hemisphere. The RSIG values were significantly different between the subjects with glioma and meningioma (P < 0.01), with no overlap between RSIG values across the two tumors. The results indicate that the quantitative changes in the RSIG values could be applied in the differential diagnosis of glioma and meningioma, and their adoption in clinical diagnosis and treatment could be helpful and informative. PMID:27006934

  14. Incidence and Predictors of Catheterization-Related Cerebral Infarction on Diffusion-Weighted Magnetic Resonance Imaging

    PubMed Central

    Okano, Mitsumasa; Suu, Kanae; Kimura, Masahiro; Minamino-Muta, Eri; Nakane, Eisaku; Izumi, Toshiaki; Miyamoto, Shoichi; Haruna, Tetsuya; Ueyama, Koji

    2016-01-01

    Introduction. The aim of this study was to examine the incidence and risk factors of catheterization-related CI in the contemporary era, using diffusion-weighted magnetic resonance imaging. Methods. We retrospectively analyzed consecutive 84 patients who underwent MRI (magnetic resonance imaging) after 2.81 ± 2.4 days (mean ± SD) of catheterization via aortic arch. We categorized the patients by the presence or absence of acute CI determined by diffusion-weighted MRI and analyzed the incidence and predictors. Results. Of 84 patients that underwent MRI after catheterization, acute CI was determined in 27 (32.1%) patients. In univariate analysis, dyslipidemia, age, coronary artery disease, antiplatelet agents, number of catheters used, urgent settings, and interventional procedures were significantly different. Multivariate analysis revealed dyslipidemia (odds ratio [OR], 4.46; 95% confidence interval [CI], 1.41–16.03; p = 0.01), higher age (OR, 1.09; 95% CI, 1.007–1.19; p = 0.03), and the number of catheters used (OR, 2.21; 95% CI, 1.21–4.36; p = 0.01) as independent predictors of the incidence of catheterization-related acute CI. Conclusions. Dyslipidemia, higher age, and number of catheters used were independent predictors for acute CI after catheterization. These findings imply that managing dyslipidemia and comprehensive planning to minimize the numbers of catheters are important. PMID:27127790

  15. Diagnostic Performance of Diffusion-weighted Magnetic Resonance Imaging in Bone Malignancy: Evidence From a Meta-Analysis.

    PubMed

    Liu, Li-Peng; Cui, Long-Biao; Zhang, Xin-Xin; Cao, Jing; Chang, Ning; Tang, Xing; Qi, Shun; Zhang, Xiao-Liang; Yin, Hong; Zhang, Jian

    2015-11-01

    Current state-of-the-art nuclear medicine imaging methods (such as PET/CT or bone scintigraphy) may have insufficient sensitivity for predicting bone tumor, and substantial exposure to ionizing radiation is associated with the risk of secondary cancer development. Diffusion-weighted MRI (DW-MRI) is radiation free and requires no intravenous contrast media, and hence is more suitable for population groups that are vulnerable to ionizing radiation and/or impaired renal functions. This meta-analysis was conducted to investigate whether whole-body DW-MRI is a viable means in differentiating bone malignancy. Medline and Embase databases were searched from their inception to May 2015 without language restriction for studies evaluating DW-MRI for detection of bone lesions. Methodological quality was assessed by the quality assessment of diagnostic studies (QUADAS-2) instrument. Sensitivities, specificities, diagnostic odds ratio (DOR), and areas under the curve (AUC) were used as measures of the diagnostic accuracy. We combined the effects by using the random-effects mode. Potential threshold effects and publication bias were investigated. We included data from 32 studies with 1507 patients. The pooled sensitivity, specificity, and AUC were 0.95 (95% CI, 0.90-0.97), 0.92 (95% CI, 0.88-0.95), and 0.98 on a per-patient basis, and they were 0.91 (95% CI, 0.87-0.94), 0.94 (95% CI, 0.90-0.96), and 0.97 on a per-lesion basis. In subgroup analysis, there is no statistical significance found in the sensitivity and specificity of using DWI only and DWI combined with other morphological or functional imaging sequence in both basis (P > 0.05). A b value of 750 to 1000 s/mm enables higher AUC and DOR for whole-body imaging purpose when compared with other values in both basis either (P < 0.01). The ROC space did not show a curvilinear trend of points and a threshold effect was not observed. According to the Deek's plots, there was no publication bias on both basis. Our

  16. Diffusion-Weighted Imaging in Meningioma: Prediction of Tumor Grade and Association with Histopathological Parameters12

    PubMed Central

    Surov, Alexey; Gottschling, Sebastian; Mawrin, Christian; Prell, Julian; Spielmann, Rolf Peter; Wienke, Andreas; Fiedler, Eckhard

    2015-01-01

    OBJECTIVES: To analyze diffusion-weighted imaging (DWI) findings of meningiomas and to compare them with tumor grade, cell count, and proliferation index and to test a possibility of use of apparent diffusion coefficient (ADC) to differentiate benign from atypical/malignant tumors. METHODS: Forty-nine meningiomas were analyzed. DWI was done using a multislice single-shot echo-planar imaging sequence. A polygonal region of interest was drawn on ADC maps around the margin of the lesion. In all lesions, minimal ADC values (ADCmin) and mean ADC values (ADCmean) were estimated. Normalized ADC (NADC) was calculated in every case as a ratio ADCmean meningioma/ADCmean white matter. All meningiomas were surgically resected and analyzed histopathologically. The tumor proliferation index was estimated on Ki-67 antigen–stained specimens. Cell density was calculated. Collected data were evaluated by means of descriptive statistics. Analyses of ADC/NADC values were performed by means of two-sided t tests. RESULTS: The mean ADCmean value was higher in grade I meningiomas in comparison to grade II/III tumors (0.96 vs 0.80 × 10− 3 mm2s− 1, P = .006). Grade II/III meningiomas showed lower NADC values in comparison to grade I tumors (1.05 vs 1.26, P = .015). There was no significant difference in ADCmin values between grade I and II/III tumors (0.69 vs 0.63 × 10− 3 mm2s− 1, P = .539). The estimated cell count varied from 486 to 2091 (mean value, 1158.20 ± 333.74; median value, 1108). There were no significant differences in cell count between grade I and grade II/III tumors (1163.93 vs 1123.86 cells, P = .77). The mean level of the proliferation index was 4.78 ± 5.08%, the range was 1% to 18%, and the median value was 2%. The proliferation index was statistically significant higher in grade II/III meningiomas in comparison to grade I tumors (15.43% vs 3.00%, P = .001). Ki-67 was negatively associated with ADCmean (r = − 0.61, P < .001) and NADC (r = − 0.60, P

  17. Whole-Body Diffusion-weighted Imaging in Hodgkin Lymphoma and Diffuse Large B-Cell Lymphoma.

    PubMed

    Toledano-Massiah, Sarah; Luciani, Alain; Itti, Emmanuel; Zerbib, Pierre; Vignaud, Alexandre; Belhadj, Karim; Baranes, Laurence; Haioun, Corinne; Lin, Chieh; Rahmouni, Alain

    2015-01-01

    Whole-body imaging, in particular molecular imaging with fluorine 18 ((18)F)-fluorodeoxyglucose (FDG) positron emission tomography (PET), is essential to management of lymphoma. The assessment of disease extent provided by use of whole-body imaging is mandatory for planning appropriate treatment and determining patient prognosis. Assessment of treatment response allows clinicians to tailor the treatment strategy during therapy if necessary and to document complete remission at the end of treatment. Because of rapid technical developments, such as echo-planar sequences, parallel imaging, multichannel phased-array surface coils, respiratory gating, and moving examination tables, whole-body diffusion-weighted (DW) magnetic resonance (MR) imaging that reflects cell density is now feasible in routine clinical practice. Whole-body DW MR imaging allows anatomic assessment as well as functional and quantitative evaluation of tumor sites by calculation of the apparent diffusion coefficient (ADC). Because of their high cellularity and high nucleus-to-cytoplasm ratio, lymphomatous lesions have low ADC values and appear hypointense on ADC maps. As a result, whole-body DW MR imaging with ADC mapping has become a promising tool for lymphoma staging and treatment response assessment. The authors review their 4 years of experience with 1.5-T and 3-T whole-body DW MR imaging used with (18)F-FDG PET/computed tomography at baseline, interim, and end of treatment in patients with Hodgkin lymphoma and diffuse large B-cell lymphoma and discuss the spectrum of imaging findings and potential pitfalls, limitations, and challenges associated with whole-body DW MR imaging in these patients. PMID:25815803

  18. Differentiation between Graves' disease and painless thyroiditis by diffusion-weighted imaging, thyroid iodine uptake, thyroid scintigraphy and serum parameters

    PubMed Central

    MENG, ZHAOWEI; ZHANG, GUIZHI; SUN, HAORAN; TAN, JIAN; YU, CHUNSHUN; TIAN, WEIJUN; LI, WEIDONG; YANG, ZHIQIANG; ZHU, MEI; HE, QING; ZHANG, YUJIE; HAN, SHUGAO

    2015-01-01

    The aim of the present study was to assess the apparent diffusion coefficient (ADC) in diffusion-weighted imaging (DWI), thyroid radioactive iodine uptake (RAIU), thyroid scintigraphy and thyrotropin receptor antibody (TRAb) levels in the differential diagnosis between Graves' disease (GD) and painless thyroiditis (PT). A total of 102 patients with GD and 37 patients with PT were enrolled in the study. DWI was obtained with a 3.0-T magnetic resonance scanner, and ADC values were calculated. RAIU and thyroid scintigraphy were performed. Tissue samples were obtained from patients with GD (6 cases) following thyroidectomy, and from patients with PT (2 cases) following biopsy. Receiver operating characteristic (ROC) curves were drawn, optimal cut-off values were selected, and the sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were assessed. It was found that the ADC, TRAb and RAIU were significantly higher in GD than in PT (P<0.05). ROC curves showed areas under the curves for RAIU, ADC and TRAb that were >0.900. RAIU was the reference method. Sensitivity, specificity, accuracy, PPV and NPV were 96.078, 91.892, 95.000, 97.059 and 89.474% for ADC, and 88.235, 75.676, 84.892, 90.909 and 70.000% for TRAb, after the optimal thresholds of 1.837×10−3 mm2/sec and 1.350 IU/ml were determined respectively. Histopathology showed that tissue cellularity in PT was much higher than in GD due to massive lymphocytic infiltration. The results of the present study indicate that RAIU, ADC and TRAb are of diagnostic value for differentiating between GD and PT. DWI has great potential for thyroid pathophysiological imaging because it reflects differences in tissue cellularity between GD and PT. PMID:26136954

  19. Sequential Cranial Ultrasound and Cerebellar Diffusion Weighted Imaging Contribute to the Early Prognosis of Neurodevelopmental Outcome in Preterm Infants

    PubMed Central

    Brouwer, Margaretha J.; van Kooij, Britt J. M.; van Haastert, Ingrid C.; Koopman-Esseboom, Corine; Groenendaal, Floris; de Vries, Linda S.; Benders, Manon J. N. L.

    2014-01-01

    Objective To evaluate the contribution of sequential cranial ultrasound (cUS) and term-equivalent age magnetic resonance imaging (TEA-MRI) including diffusion weighted imaging (DWI) to the early prognosis of neurodevelopmental outcome in a cohort of very preterm infants (gestational age [GA] <31 weeks). Study design In total, 93 preterm infants (median [range] GA in weeks: 28.3 [25.0–30.9]) were enrolled in this prospective cohort study and underwent early and term cUS as well as TEA-MRI including DWI. Early cUS abnormalities were classified as normal, mild, moderate or severe. Term cUS was evaluated for ex-vacuo ventriculomegaly (VM) and enlargement of the extracerebral cerebrospinal fluid (eCSF) space. Abnormalities on T1- and T2-weighted TEA-MRI were scored according to Kidokoro et al. Using DWI at TEA, apparent diffusion coefficients (ADCs) were measured in four white matter regions bilaterally and both cerebellar hemispheres. Neurodevelopmental outcome was assessed at two years’ corrected age (CA) using the Bayley Scales of Infant and Toddler Development, third edition. Linear regression analysis was conducted to explore the correlation between the different neuroimaging modalities and outcome. Results Moderate/severe abnormalities on early cUS, ex-vacuo VM and enlargement of the eCSF space on term cUS and increased cerebellar ADC values on term DWI were independently associated with worse motor outcome (p<.05). Ex-vacuo VM on term cUS was also related to worse cognitive performance at two years’ CA (p<.01). Conclusion These data support the clinical value of sequential cUS and recommend repeating cUS at TEA. In particular, assessment of moderate/severe early cUS abnormalities and ex-vacuo VM on term cUS provides important prognostic information. Cerebellar ADC values may further aid in the prognostication of gross motor function. PMID:25329772

  20. Perianal Fistula With and Without Abscess: Assessment of Fistula Activity Using Diffusion-Weighted Magnetic Resonance Imaging

    PubMed Central

    Bakan, Selim; Olgun, Deniz Cebi; Kandemirli, Sedat Giray; Tutar, Onur; Samanci, Cesur; Dikici, Suleyman; Simsek, Osman; Rafiee, Babak; Adaletli, Ibrahim; Mihmanli, Ismail

    2015-01-01

    Background: Magnetic resonance imaging (MRI) is highly accurate for the depiction of both the primary tract of fistula and abscesses, in patients with perianal disease. In addition, MRI can be used to evaluate the activity of fistulas, which is a significant factor for determining the therapeutic strategy. Objectives: This study aimed to determine the usefulness of diffusion-weighted (DW) MRI for assessing activity and visibility of perianal fistula. Patients and Methods: Fifty-three patients with 56 perianal fistulas were included in the current retrospective study. The T2-weighted imaging (T2WI) and DWMRI were performed and apparent diffusion coefficient (ADC) values of fistulas were measured. Fistulas were classified into two groups: only perianal fistulas and fistulas accompanied by abscess. Fistulas were also classified into two groups, based on clinical findings: positive inflammatory activity (PIA) and negative inflammatory activity (NIA). Results: Mean ADC value (mm2/s) of PIA group was significantly lower than that of NIA group, regarding lesions in patients with abscess-associated fistulas (1.371 × 10-3 ± 0.168 × 10-3 vs. 1.586 × 10-3 ± 0.136 × 10-3; P = 0.036). No statistically significant difference was found in mean ADC values between PIA and NIA groups, in patients with only perianal fistulas (P = 0.507). Perianal fistula visibility was greater with combined evaluation of T2WI and DWMRI than with T2WI, for two reviewers (P = 0.046 and P = 0.014). Conclusion: The DWMRI is a useful technique for evaluating activity of fistulas with abscess. Perianal fistula visibility is greater with combined T2WI and DWMRI than T2WI alone. PMID:26715982

  1. Texture-based and diffusion-weighted discrimination of parotid gland lesions on MR images at 3.0 Tesla.

    PubMed

    Fruehwald-Pallamar, Julia; Czerny, Christian; Holzer-Fruehwald, Laura; Nemec, Stefan F; Mueller-Mang, Christina; Weber, Michael; Mayerhoefer, Marius E

    2013-11-01

    The purpose of this study was to evaluate whether texture-based analysis of standard MRI sequences and diffusion-weighted imaging can help in the discrimination of parotid gland masses. The MR images of 38 patients with a biopsy- or surgery-proven parotid gland mass were retrospectively analyzed. All patients were examined on the same 3.0 Tesla MR unit, with one standard protocol. The ADC (apparent diffusion coefficient) values of the tumors were measured with three regions of interest (ROIs) covering the entire tumor. Texture-based analysis was performed with the texture analysis software MaZda (version 4.7), with ROI measurements covering the entire tumor in three slices. COC (co-occurrence matrix), RUN (run-length matrix), GRA (gradient), ARM (auto-regressive model), and WAV (wavelet transform) features were calculated for all ROIs. Three subsets of 10 texture features each were used for a linear discriminant analysis (LDA) in combination with k nearest neighbor classification (k-NN). Using histology as a standard of reference, benign tumors, including subtypes, and malignant tumors were compared with regard to ADC and texture-based values, with a one-way analysis of variance with post-hoc t-tests. Significant differences were found in the mean ADC values between Warthin tumors and pleomorphic adenomas, as well as between Warthin tumors and benign lesions. Contrast-enhanced T1-weighted images contained the most relevant textural information for the discrimination between benign and malignant parotid masses, and also for the discrimination between pleomorphic adenomas and Warthin tumors. STIR images contained the least relevant texture features, particularly for the discrimination between pleomorphic adenomas and Warthin tumors. Texture analysis proved to differentiate benign from malignant lesions, as well as pleomorphic adenomas from Warthin tumors, based on standard T(1w) sequences (without and with contrast). Of all benign parotid masses, Warthin tumors had

  2. Diffusion-weighted intensity magnetic resonance in the preoperative diagnosis of cholesteatoma.

    PubMed

    Cavaliere, Michele; Di Lullo, Antonella Miriam; Caruso, Antonia; Caliendo, Giandomenico; Elefante, Andrea; Brunetti, Arturo; Iengo, Maurizio

    2014-01-01

    We have analyzed the preoperative diagnosis of cholesteatoma through the use of diffusion-weighted intensity magnetic resonance (DWI-MR) in 16 consecutive patients suffering from chronic otitis media with clinical and radiological (by computed tomography) suspicion of cholesteatoma. In particular, we compared the radiological data with intraoperative ones, verifying the correspondence (in terms of sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy) between what is reported by DWI-MR and what is actually detectable at the time of surgery. Furthermore, we identified the most reliable DWI-MR sequence [single-shot (SSh) echo planar imaging (EPI) vs. multi-shot turbo spin-echo not-EPI] to detect cholesteatoma and reduce the time for examination. The obtained data on computed tomography scans revealed low diagnostic accuracy (56%); DWI-MR, instead, showed higher values, especially using not-EPI sequences (93.75 vs. 68.75% obtained by SSh-EPI sequences). PMID:25322773

  3. Diffusion-weighted imaging outside the brain: Consensus statement from an ISMRM-sponsored workshop.

    PubMed

    Taouli, Bachir; Beer, Ambros J; Chenevert, Thomas; Collins, David; Lehman, Constance; Matos, Celso; Padhani, Anwar R; Rosenkrantz, Andrew B; Shukla-Dave, Amita; Sigmund, Eric; Tanenbaum, Lawrence; Thoeny, Harriet; Thomassin-Naggara, Isabelle; Barbieri, Sebastiano; Corcuera-Solano, Idoia; Orton, Matthew; Partridge, Savannah C; Koh, Dow-Mu

    2016-09-01

    The significant advances in magnetic resonance imaging (MRI) hardware and software, sequence design, and postprocessing methods have made diffusion-weighted imaging (DWI) an important part of body MRI protocols and have fueled extensive research on quantitative diffusion outside the brain, particularly in the oncologic setting. In this review, we summarize the most up-to-date information on DWI acquisition and clinical applications outside the brain, as discussed in an ISMRM-sponsored symposium held in April 2015. We first introduce recent advances in acquisition, processing, and quality control; then review scientific evidence in major organ systems; and finally describe future directions. J. Magn. Reson. Imaging 2016;44:521-540. PMID:26892827

  4. Diffusion weighted MRI of the breast: Protocol optimization, guidelines for interpretation, and potential clinical applications

    PubMed Central

    Partridge, Savannah C.; McDonald, Elizabeth S.

    2013-01-01

    Synopsis There has been increasing interest in the use of diffusion weighted MRI (DWI) for breast imaging. This technique has shown promise for improving the positive predictive value of breast MRI for detection of breast cancer, evaluating tumor response to neoadjuvant chemotherapy, and as a non-contrast MRI alternative for breast cancer screening. However, there is currently no standardized approach to DWI of the breast and data quality varies widely. Prior to implementing DWI into clinical practice, it is important to understand the pertinent technical considerations and current evidence of clinical applications of DWI of the breast. This article provides an overview of basic principles of DWI, optimization of breast DWI protocols, imaging features of benign and malignant breast lesions, promising clinical applications, and potential future directions. PMID:23928248

  5. Comparison of stroke infarction between CT perfusion and diffusion weighted imaging: preliminary results

    NASA Astrophysics Data System (ADS)

    Abd. Rahni, Ashrani Aizzuddin; Arka, Israna Hossain; Chellappan, Kalaivani; Mukari, Shahizon Azura; Law, Zhe Kang; Sahathevan, Ramesh

    2016-03-01

    In this paper we present preliminary results of comparison of automatic segmentations of the infarct core, between that obtained from CT perfusion (based on time to peak parameter) and diffusion weighted imaging (DWI). For each patient, the two imaging volumes were automatically co-registered to a common frame of reference based on an acquired CT angiography image. The accuracy of image registration is measured by the overlap of the segmented brain from both images (CT perfusion and DWI), measured within their common field of view. Due to the limitations of the study, DWI was acquired as a follow up scan up to a week after initial CT based imaging. However, we found significant overlap of the segmented brain (Jaccard indices of approximately 0.8) and the percentage of infarcted brain tissue from the two modalities were still fairly highly correlated (correlation coefficient of approximately 0.9). The results are promising with more data needed in future for clinical inference.

  6. Diffusion-weighted imaging in musculoskeletal radiology—clinical applications and future directions

    PubMed Central

    Bhojwani, Nicholas; Szpakowski, Peter; Partovi, Sasan; Maurer, Martin H.; Grosse, Ulrich; von Tengg-Kobligk, Hendrik; Zipp-Partovi, Lisa; Fergus, Nathan; Kosmas, Christos; Nikolaou, Konstantin

    2015-01-01

    Diffusion-weighted imaging (DWI) is an established diagnostic tool with regards to the central nervous system (CNS) and research into its application in the musculoskeletal system has been growing. It has been shown that DWI has utility in differentiating vertebral compression fractures from malignant ones, assessing partial and complete tears of the anterior cruciate ligament (ACL), monitoring tumor response to therapy, and characterization of soft-tissue and bone tumors. DWI is however less useful in differentiating malignant vs. infectious processes. As of yet, no definitive qualitative or quantitative properties have been established due to reasons ranging from variability in acquisition protocols to overlapping imaging characteristics. Even with these limitations, DWI can still provide clinically useful information, increasing diagnostic accuracy and improving patient management when magnetic resonance imaging (MRI) findings are inconclusive. The purpose of this article is to summarize recent research into DWI applications in the musculoskeletal system. PMID:26682143

  7. Sensitivity of Diffusion-Weighted STEAM MRI and EPI-DWI to Infratentorial Ischemic Stroke

    PubMed Central

    Hohenhaus, Marc; Kunze, Claudia; Schmidt, Wolf; Brunecker, Peter; Villringer, Kersten; Merboldt, Klaus-Dietmar; Frahm, Jens; Fiebach, Jochen B.

    2016-01-01

    Objectives To assess the sensitivity of stimulated echo acquisition mode diffusion weighted imaging (STEAM-DWI) to ischemic stroke in comparison to echo-planar imaging diffusion weighted imaging (EPI-DWI) in the infratentorial compartment. Methods Fifty-seven patients presenting with clinical features of infratentorial stroke underwent STEAM-DWI, high-resolution EPI-DWI (HR-DWI, 2.5 mm slice thickness) and low-resolution EPI-DWI (LR-DWI, 5 mm slice thickness). Four readers assessed the presence of ischemic lesions and artifacts. Agreement between sequences and interobserver agreement on the presence of ischemia were calculated. The sensitivities of the DWI sequences were calculated in 45 patients with a confirmed diagnosis of infratentorial stroke. Results Median time from symptom onset to imaging was 24 hours. STEAM-DWI agreed with LR-DWI in 89.5% of cases (kappa = 0.72, p<0.0001) and with HR-DWI in 89.5% of cases (kappa = 0.68, p<0.0001). STEAM-DWI showed fewer intraparenchymal artifacts (1/57) than HR-DWI (44/57) and LR-DWI (41/57). Ischemia was visible in 87% of cases for LR-DWI, 93% of cases for HR-DWI, and 89% of cases for STEAM-DWI. Interobserver agreement was good for STEAM-DWI (kappa = 0.62, p<0.0001). Conclusions Compared to the best currently available MR sequence for detecting ischemia (HR-DWI), STEAM-DWI shows fewer artifacts and a similar sensitivity to infratentorial stroke. PMID:27529697

  8. Evaluation of Angiographic and Technical Aspects of Carotid Stenting with Diffusion-Weighted Magnetic Resonance Imaging

    SciTech Connect

    Blasel, Stella Hattingen, Elke; Berkefeld, Joachim; Kurre, Wiebke; Morawe, Gerald; Zanella, Friedhelm; Rochemont, Richard Du Mesnil de

    2009-07-15

    The detection of clinically silent ischemic lesions on postprocedural diffusion-weighted magnetic resonance images has become a preferred method for the description of embolic risks. The purpose of this single-center study was to evaluate whether diffusion-weighted imaging (DWI) could determine material related or technical risk factors of filter-protected carotid stenting. Eighty-four patients with symptomatic severe ({>=}60%) carotid artery stenoses received filter-protected carotid stenting. Standard DWI (b = 1000) was performed within 48 h before and after carotid stenting. The occurrence and load of new postinterventional DWI lesions were assessed. Multivariate analysis was performed to determine risk factors associated with DWI lesions, with emphasis on technical factors such as use of different access devices (guiding catheter method vs. long carotid sheath method), type of stent (open-cell nitinol stent vs. closed-cell Wallstent), and protective device (filters with 80-{mu}m vs. 110-120-{mu}m pore size). Markers for generalized atherosclerosis and for degree and site of stenosis were assessed to allow comparison of adequate risk profiles. Access, protective device, and stent type were not significantly associated with new embolic DWI lesions when we compared patients with equivalent risk profiles (long carotid sheath method 48% [11 of 23] vs. guiding catheter method 44% [27 of 61], Wallstent 47% [15 of 32] vs. nitinol stent 44% [23 of 52], and small pore size filter 61% [11 of 18] vs. large pore size filter 41% [27 of 66]). Single-center DWI studies with a moderate number of cases are inadequate for proper assessment of the embolic risk of technical- or material-related risk factors in carotid stenting. Larger multicenter studies with more cases are needed.

  9. Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS): features and potential applications in oncology

    PubMed Central

    Takahara, Taro; Ochiai, Reiji; Nievelstein, Rutger A. J.; Luijten, Peter R.

    2008-01-01

    Diffusion-weighted magnetic resonance imaging (DWI) provides functional information and can be used for the detection and characterization of pathologic processes, including malignant tumors. The recently introduced concept of “diffusion-weighted whole-body imaging with background body signal suppression” (DWIBS) now allows acquisition of volumetric diffusion-weighted images of the entire body. This new concept has unique features different from conventional DWI and may play an important role in whole-body oncological imaging. This review describes and illustrates the basics of DWI, the features of DWIBS, and its potential applications in oncology. Electronic supplementary material The online version of this article (doi:10.1007/s00330-008-0968-z) contains supplementary material, which is available to authorized users. PMID:18446344

  10. Cyst infection in unilateral renal cystic disease and the role of diffusion-weighted magnetic resonance imaging.

    PubMed

    Takase, Yasukazu; Kodama, Koichi; Motoi, Isamu; Saito, Katsuhiko

    2012-11-01

    In multicystic renal diseases, cyst infection is a complex issue because of the absence of validated diagnostic methods. Unilateral renal cystic disease is a rare multicystic disease, believed to have an acquired maldevelopmental origin. Unilateral renal cystic disease is often confused with autosomal dominant polycystic kidney disease but has some distinguishing characteristics: unilateral localization, negative family history, and no progression to chronic renal failure. We describe a case of unilateral renal cystic disease with cyst infection that could be detected by diffusion-weighted magnetic resonance imaging, but not by conventional imaging techniques. Diffusion-weighted magnetic resonance imaging can be useful for detecting infected cysts, especially in multicystic renal diseases. PMID:22990058

  11. Precursor times of abnormal b-values prior to mainshocks

    NASA Astrophysics Data System (ADS)

    Wang, Jeen-Hwa; Chen, Kou-Cheng; Leu, Peih-Lin; Chang, Chien-Hsin

    2016-07-01

    Seismic observations exhibit the presence of abnormal b-values prior to numerous earthquakes. The time interval from the appearance of abnormal b-values to the occurrence of mainshock is called the precursor time. There are two kinds of precursor times in use: the first one denoted by T is the time interval from the moment when the b-value starts to increase from the normal one to the abnormal one to the occurrence time of the forthcoming mainshock, and the second one denoted by T p is the time interval from the moment when the abnormal b-value reaches the peak one to the occurrence time of the forthcoming mainshock. Let T* be the waiting time from the moment when the abnormal b-value returned to the normal one to the occurrence time of the forthcoming mainshock. The precursor time, T (usually in days), has been found to be related to the magnitude, M, of the mainshock expected in a linear form as log( T) = q + rM where q and r are the coefficient and slope, respectively. In this study, the values of T, T p , and T* of 45 earthquakes with 3 ≤ M ≤ 9 occurred in various tectonic regions are compiled from or measured from the temporal variations in b-values given in numerous source materials. The relationships of T and T p , respectively, versus M are inferred from compiled data. The difference between the values of T and T p decreases with increasing M. In addition, the plots of T*/ T versus M, T* versus T, and T* versus T- T* will be made and related equations between two quantities will be inferred from given data.

  12. FDG-MicroPET and Diffusion-Weighted MR Image Evaluation of Early Changes After Radiofrequency Ablation in Implanted VX2 Tumors in Rabbits

    SciTech Connect

    Ohira, Tomohiro Okuma, Tomohisa; Matsuoka, Toshiyuki; Wada, Yasuhiro; Nakamura, Kenji; Watanabe, Yasuyoshi; Inoue, Yuichi

    2009-01-15

    The objective of this study was to evaluate the early changes after radiofrequency ablation (RFA) in VX2 rabbit tumors implanted into the back muscles by diffusion-weighted magnetic resonance (MR) imaging and {sup 18}F-2-fluoro-2-deoxy-D-glucose positron emission tomography ({sup 18}F-FDG PET). Percutaneous CT-guided RFA was conducted in seven rabbits with implanted VX2 tumors. VX2 tumors on the other side were untreated and served as the control. MR imaging was performed with a clinical 1.5-T instrument 2 days after RFA, and FDG-PET, using a high-resolution PET scanner for small animals, was obtained 3 days after the procedure. The mean apparent diffusion coefficient (ADC) values and radioactivity count of untreated and ablated tumors were calculated. Untreated VX2 tumors showed hyperintensity on T1-, T2-, and diffusion-weighted MR images, ring-enhanced on contrast-enhanced T1-weighted imaging, and ring-shaped FDG accumulation on FDG-PET. Ablated VX2 tumors showed slight hyperintensity on T1-, T2-, and diffusion-weighed images, slight enhancement on contrast-enhanced T1-weighted images, and low accumulation on FDG-PET. The ADC value of ablated VX2 tumors (1.52 {+-} 0.24 x 10{sup -3} mm{sup 2}/s) was significantly higher than that of untreated tumors (1.09 {+-} 0.12 x 10{sup -3}; p < 0.05). The tumor/muscle ratio of ablated tumors (0.5 {+-} 0.3) was significantly lower than that of untreated tumors (11.6 {+-} 3.2; p < 0.05). Histopathological examination confirmed the lack of viable tumor cells in the ablated lesions. The results indicate that both ADC value and FDG-PET are potentially useful markers for monitoring the early effects of RFA.

  13. Differential Diagnosis of Axillary Inflammatory and Metastatic Lymph Nodes in Rabbit Models by Using Diffusion-Weighted Imaging: Compared with Conventional Magnetic Resonance Imaging

    PubMed Central

    Liao, Qian; Zhang, Yunting; Yu, Chunshui; Bai, Renju; Sun, Haoran

    2012-01-01

    Objective This experiment aims to determine the diagnostic value of diffusion-weighted imaging (DWI) in the differentiation of axillary inflammatory lymph nodes from metastatic lymph nodes in rabbit models in comparison with conventional magnetic resonance imaging (MRI). Materials and Methods Conventional MRI and DWI were performed at 4 weeks after successful inoculation into the forty female New Zealand white rabbits' mammary glands. The size-based and signal-intensity-based criteria and the relative apparent diffusion coefficient (rADC) value were compared between the axillary inflammatory lymph nodes and metastatic lymph nodes, with histopathological findings as the reference standard. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic performance of the aforementioned criteria and rADC value in differentiating the axillary inflammatory lymph nodes from metastatic lymph nodes. Results Thirty-two axillary inflammatory lymph nodes and 46 metastatic ones were successfully isolated and taken into pathological analysis. The differences of the aforementioned criteria between the two groups were not statistically significant (p > 0.05). However, the rADC value of the inflammatory lymph nodes (0.9 ± 0.14) was higher than that of metastatic ones (0.7 ± 0.18), with significant difference (p = 0.016). When the rADC value was chosen as 0.80, the area under the ROC curve is greater than all other criteria, and the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for differentiating two groups were 86.2%, 79.3%, 81.2%, 84.2%, and 85.6%, respectively. Conclusion Diffusion-weighted imaging is a promising new technique for differentiating axillary inflammatory lymph nodes from metastatic lymph nodes. Compared with routine magnetic resonance sequences, DWI could provide more useful physiological and functional information for diagnosis. PMID:22778568

  14. Increasing the Accuracy of Volume and ADC Delineation for Heterogeneous Tumor on Diffusion-Weighted MRI: Correlation with PET/CT

    SciTech Connect

    Gong, Nan-Jie; Wong, Chun-Sing; Chu, Yiu-Ching; Guo, Hua; Huang, Bingsheng; Chan, Queenie

    2013-10-01

    Purpose: To improve the accuracy of volume and apparent diffusion coefficient (ADC) measurements in diffusion-weighted magnetic resonance imaging (MRI), we proposed a method based on thresholding both the b0 images and the ADC maps. Methods and Materials: In 21 heterogeneous lesions from patients with metastatic gastrointestinal stromal tumors (GIST), gross lesion were manually contoured, and corresponding volumes and ADCs were denoted as gross tumor volume (GTV) and gross ADC (ADC{sub g}), respectively. Using a k-means clustering algorithm, the probable high-cellularity tumor tissues were selected based on b0 images and ADC maps. ADC and volume of the tissues selected using the proposed method were denoted as thresholded ADC (ADC{sub thr}) and high-cellularity tumor volume (HCTV), respectively. The metabolic tumor volume (MTV) in positron emission tomography (PET)/computed tomography (CT) was measured using 40% maximum standard uptake value (SUV{sub max}) as the lower threshold, and corresponding mean SUV (SUV{sub mean}) was also measured. Results: HCTV had excellent concordance with MTV according to Pearson's correlation (r=0.984, P<.001) and linear regression (slope = 1.085, intercept = −4.731). In contrast, GTV overestimated the volume and differed significantly from MTV (P=.005). ADC{sub thr} correlated significantly and strongly with SUV{sub mean} (r=−0.807, P<.001) and SUV{sub max} (r=−0.843, P<.001); both were stronger than those of ADC{sub g}. Conclusions: The proposed lesion-adaptive semiautomatic method can help segment high-cellularity tissues that match hypermetabolic tissues in PET/CT and enables more accurate volume and ADC delineation on diffusion-weighted MR images of GIST.

  15. Comparison of dynamic contrast-enhanced and diffusion weighted magnetic resonance image in staging and grading of carcinoma bladder with histopathological correlation

    PubMed Central

    Gupta, Neetika; Sureka, Binit; Kumar, Mittal Mahesh; Malik, Amita; Bhushan, Thukral Brij; Mohanty, N. K.

    2015-01-01

    Background: Bladder cancer is the second most common neoplasm of the urinary tract worldwide. Dynamic contrast-enhanced and diffusion-weighted MRI has been introduced in clinical MRI protocols of bladder cancer because of its accuracy in staging and grading. Aim: To evaluate and compare accuracy of Dynamic contrast enhanced (DCE) and Diffusion weighted (DW) MRI for preoperative T staging of urinary bladder cancer and find correlation between apparent diffusion coefficient (ADC) and maximum enhancement with histological grade. Materials and Methods: Sixty patients with bladder cancer were included in study. All patients underwent Magnetic Resonance Imaging (MRI) on a 1.5-T scanner with a phased-array pelvic coil. MR images were evaluated and assigned a stage which was compared with the histolopathological staging. ADC value and maximum enhancement curve were used based on previous studies. Subsequently histological grade was compared with MR characteristics. Results: The extent of agreement between the radiologic staging and histopathological staging was relatively greater with the DW-MRI (κ=0.669) than DCE-MRI (κ=0.619). The sensitivity, specificity, and accuracy are maximum and similar for stage T4 tumors in both DCEMRI (100.0, 96.2 and 96.7) and DW-MRI (100.0, 96.2 and 96.7) while minimum for stage T2 tumors - DCEMRI (83.3, 72.2, and 76.7) and DWI-MRI (91.7, 72.2, and 80). Conclusion: MRI is an effective tool for determining T stage and histological grade of urinary bladder cancers. Stage T2a and T2b can be differentiated only by DCE-MRI. Results were more accurate when both ADC and DCE-MRI were used together and hence a combined approach is suggested. PMID:25835087

  16. Fast and accurate simulations of diffusion-weighted MRI signals for the evaluation of acquisition sequences

    NASA Astrophysics Data System (ADS)

    Rensonnet, Gaëtan; Jacobs, Damien; Macq, Benoît.; Taquet, Maxime

    2016-03-01

    Diffusion-weighted magnetic resonance imaging (DW-MRI) is a powerful tool to probe the diffusion of water through tissues. Through the application of magnetic gradients of appropriate direction, intensity and duration constituting the acquisition parameters, information can be retrieved about the underlying microstructural organization of the brain. In this context, an important and open question is to determine an optimal sequence of such acquisition parameters for a specific purpose. The use of simulated DW-MRI data for a given microstructural configuration provides a convenient and efficient way to address this problem. We first present a novel hybrid method for the synthetic simulation of DW-MRI signals that combines analytic expressions in simple geometries such as spheres and cylinders and Monte Carlo (MC) simulations elsewhere. Our hybrid method remains valid for any acquisition parameters and provides identical levels of accuracy with a computational time that is 90% shorter than that required by MC simulations for commonly-encountered microstructural configurations. We apply our novel simulation technique to estimate the radius of axons under various noise levels with different acquisition protocols commonly used in the literature. The results of our comparison suggest that protocols favoring a large number of gradient intensities such as a Cube and Sphere (CUSP) imaging provide more accurate radius estimation than conventional single-shell HARDI acquisitions for an identical acquisition time.

  17. New paradigm to assess brain cell morphology by diffusion-weighted MR spectroscopy in vivo.

    PubMed

    Palombo, Marco; Ligneul, Clémence; Najac, Chloé; Le Douce, Juliette; Flament, Julien; Escartin, Carole; Hantraye, Philippe; Brouillet, Emmanuel; Bonvento, Gilles; Valette, Julien

    2016-06-14

    The brain is one of the most complex organs, and tools are lacking to assess its cellular morphology in vivo. Here we combine original diffusion-weighted magnetic resonance (MR) spectroscopy acquisition and novel modeling strategies to explore the possibility of quantifying brain cell morphology noninvasively. First, the diffusion of cell-specific metabolites is measured at ultra-long diffusion times in the rodent and primate brain in vivo to observe how cell long-range morphology constrains metabolite diffusion. Massive simulations of particles diffusing in synthetic cells parameterized by morphometric statistics are then iterated to fit experimental data. This method yields synthetic cells (tentatively neurons and astrocytes) that exhibit striking qualitative and quantitative similarities with histology (e.g., using Sholl analysis). With our approach, we measure major interspecies difference regarding astrocytes, whereas dendritic organization appears better conserved throughout species. This work suggests that the time dependence of metabolite diffusion coefficient allows distinguishing and quantitatively characterizing brain cell morphologies noninvasively. PMID:27226303

  18. Anisotropy Induced by Macroscopic Boundaries: Surface-Normal Mapping using Diffusion-Weighted Imaging

    PubMed Central

    Özarslan, Evren; Nevo, Uri; Basser, Peter J.

    2008-01-01

    In MRI, macroscopic boundaries lead to a diffusion-related increase in signal intensity near them—an effect commonly referred to as edge-enhancement. In diffusion-weighted imaging protocols where the signal attenuation due to diffusion results predominantly from the application of magnetic field gradients, edge-enhancement will depend on the orientation of these diffusion gradients. The resulting diffusion anisotropy can be exploited to map the direction normal to the macroscopic boundary. Simulations suggest that the hypothesized anisotropy may be within observable limits even when the voxel contains no boundary itself—hence, the name remote-anisotropy. Moreover, for certain experimental parameters there may be significant phase cancellations within the voxel that may lead to an edge detraction effect. When this is avoided, the eigenvector corresponding to the smallest eigenvalue of the diffusion tensor obtained from diffusion-tensor imaging can be used to create surface-normal maps conveniently. Experiments performed on simple geometric constructs as well as real tissue demonstrate the feasibility of using the edge-enhancement mechanism to map orientations orthogonal to macroscopic surfaces, which may be used to assess the integrity of tissue and organ boundaries noninvasively. PMID:18065457

  19. Robust optimization of diffusion-weighted MRI protocols used for fiber reconstruction

    NASA Astrophysics Data System (ADS)

    Majumdar, S.; Udpa, S. S.; Raguin, L. G.

    2008-11-01

    Diffusion-weighted imaging (DWI) is a magnetic resonance imaging (MRI) technique that employs diffusion-encoding gradients to sensitize the signal to the diffusion of water molecules. DWI allows the noninvasive and quantitative probing of opaque structures such as fibrous soft tissues. Model-based DWI post-processing algorithms, such as diffusion tensor imaging (DTI), solve an inverse problem to estimate from a series of DWI data a set of model parameters representing the diffusion process and the environment of the water molecules. DWI models connect the model parameters (e.g., fiber orientations for fibrous soft tissues) with the experimental parameters (e.g., strengths and directions of the 3-D diffusion-encoding gradients). For spinal cord injuries and skeletal muscle characterization, the fiber orientations within the imaged region can be approximately known a priori using localizer images. Then, we propose and implement a model-based robust optimization framework for two axisymmetric diffusion models, producing robust DWI protocols with respect to the approximate knowledge of the fiber orientations within the images, thereby reducing the uncertainty in the parameter estimates caused by experimental noise. Our goal is to improve the yield of quantitative DWI diagnostics used in clinical and preclinical trials by minimizing the experimental uncertainty.

  20. An adaptive diffusion-weighted whole-body magnetic resonance imaging scheme using the multistation approach

    NASA Astrophysics Data System (ADS)

    Han, Yeji

    2016-02-01

    Whole-body diffusion-weighted imaging (DWI) is a useful tool in oncology, which enables fast screening of disseminated tumors, lymph nodes or abscesses in the body. Multistation magnetic resonance imaging (MRI) or continuously moving table (CMT) MRI can be performed to overcome the limited field of view (FOV) of the magnet bore in whole-body DWI. Although CMT-MRI is regarded as a more advanced form of whole-body MRI, it cannot be widely used because most of the available MR systems are not equipped with the required hardware/software to perform CMT. Thus, optimizing the multistation approach for whole-body DWI, which is more widely available and easier to perform with the existing MR systems, is worthwhile. To improve the quality of DW images acquired with the multistation approach, we used different combinations of the built-in body RF coil and the phased-array surface RF coils for reception of the signals in whole-body DWI in this work. If different coils are selectively used in the extended FOV and appropriate reconstruction algorithms are exploited, the screening ability of whole-body DWI can be improved while minimizing the patient's discomfort and the artifacts due to physiological motions.

  1. Advanced Diffusion-Weighted Magnetic Resonance Imaging Techniques of the Human Spinal Cord

    PubMed Central

    Andre, Jalal B.; Bammer, Roland

    2012-01-01

    Unlike those of the brain, advances in diffusion-weighted imaging (DWI) of the human spinal cord have been challenged by the more complicated and inhomogeneous anatomy of the spine, the differences in magnetic susceptibility between adjacent air and fluid-filled structures and the surrounding soft tissues, and the inherent limitations of the initially used echo-planar imaging techniques used to image the spine. Interval advances in DWI techniques for imaging the human spinal cord, with the specific aims of improving the diagnostic quality of the images, and the simultaneous reduction in unwanted artifacts have resulted in higher-quality images that are now able to more accurately portray the complicated underlying anatomy and depict pathologic abnormality with improved sensitivity and specificity. Diffusion tensor imaging (DTI) has benefited from the advances in DWI techniques, as DWI images form the foundation for all tractography and DTI. This review provides a synopsis of the many recent advances in DWI of the human spinal cord, as well as some of the more common clinical uses for these techniques, including DTI and tractography. PMID:22158130

  2. New paradigm to assess brain cell morphology by diffusion-weighted MR spectroscopy in vivo

    PubMed Central

    Palombo, Marco; Ligneul, Clémence; Najac, Chloé; Le Douce, Juliette; Flament, Julien; Escartin, Carole; Hantraye, Philippe; Brouillet, Emmanuel; Bonvento, Gilles; Valette, Julien

    2016-01-01

    The brain is one of the most complex organs, and tools are lacking to assess its cellular morphology in vivo. Here we combine original diffusion-weighted magnetic resonance (MR) spectroscopy acquisition and novel modeling strategies to explore the possibility of quantifying brain cell morphology noninvasively. First, the diffusion of cell-specific metabolites is measured at ultra-long diffusion times in the rodent and primate brain in vivo to observe how cell long-range morphology constrains metabolite diffusion. Massive simulations of particles diffusing in synthetic cells parameterized by morphometric statistics are then iterated to fit experimental data. This method yields synthetic cells (tentatively neurons and astrocytes) that exhibit striking qualitative and quantitative similarities with histology (e.g., using Sholl analysis). With our approach, we measure major interspecies difference regarding astrocytes, whereas dendritic organization appears better conserved throughout species. This work suggests that the time dependence of metabolite diffusion coefficient allows distinguishing and quantitatively characterizing brain cell morphologies noninvasively. PMID:27226303

  3. A novel tensor distribution model for the diffusion-weighted MR signal.

    PubMed

    Jian, Bing; Vemuri, Baba C; Ozarslan, Evren; Carney, Paul R; Mareci, Thomas H

    2007-08-01

    Diffusion MRI is a non-invasive imaging technique that allows the measurement of water molecule diffusion through tissue in vivo. The directional features of water diffusion allow one to infer the connectivity patterns prevalent in tissue and possibly track changes in this connectivity over time for various clinical applications. In this paper, we present a novel statistical model for diffusion-weighted MR signal attenuation which postulates that the water molecule diffusion can be characterized by a continuous mixture of diffusion tensors. An interesting observation is that this continuous mixture and the MR signal attenuation are related through the Laplace transform of a probability distribution over symmetric positive definite matrices. We then show that when the mixing distribution is a Wishart distribution, the resulting closed form of the Laplace transform leads to a Rigaut-type asymptotic fractal expression, which has been phenomenologically used in the past to explain the MR signal decay but never with a rigorous mathematical justification until now. Our model not only includes the traditional diffusion tensor model as a special instance in the limiting case, but also can be adjusted to describe complex tissue structure involving multiple fiber populations. Using this new model in conjunction with a spherical deconvolution approach, we present an efficient scheme for estimating the water molecule displacement probability functions on a voxel-by-voxel basis. Experimental results on both simulations and real data are presented to demonstrate the robustness and accuracy of the proposed algorithms. PMID:17570683

  4. Diffusion weighted magnetic resonance imaging for acute stroke: practical and popular

    PubMed Central

    Tan, P L; King, D; Durkin, C J; Meagher, T M; Briley, D

    2006-01-01

    Aim To evaluate the feasibility and impact of diffusion weighted magnetic resonance imaging (DW MRI) as the first line neuroimaging of stroke at a district general hospital. Methods Prospective audit of all in‐patients admitted with clinically suspected acute stroke and referred for imaging over a consecutive 17 week period. The data collected included scan type, time from cerebral event to imaging request, and time from formal radiological request to neuroimaging. Clinicians' (general physicians, neurologists, and radiologists) perceptions were assessed by a questionnaire. Results 148 patients had neuroimaging for clinically suspected stroke during this period. Eighty one per cent of patients (120 of 148) had DW MRI as first line. Ninety two per cent of these patients had DW MRI within 24 hours of the formal radiological request. Twenty eight patients did not undergo DW MRI because lack of MRI safety, clinical state, unavailability because of maintenance service or lack of trained staff. Clinicians found the introduction of the DW MRI based service a significant improvement on computed tomography, especially for equivocal cases. Conclusion DW based MRI service is both feasible and sustainable in the setting of a district general hospital and most clinicians feel that this is a significant improvement to stroke services. PMID:16597819

  5. Advantage of Adding Diffusion Weighted Imaging to Routine MRI Examinations in the Diagnostics of Scrotal Lesions

    PubMed Central

    Algebally, Ahmed Mohamed; Tantawy, Hazim Ibrahim; Yousef, Reda Ramadan Hussein; Szmigielski, Wojciech; Darweesh, Adham

    2015-01-01

    Summary Background The purpose of the study is to identify the diagnostic value of adding diffusion weighted images (DWI) to routine MRI examinations of the scrotum. Material/Methods The study included 100 testes of 50 patients with a unilateral testicular disease. Fifty normal contralateral testes were used as a control group. All patients underwent conventional MRI and DWI examinations of the scrotum. The results of MRI and DWI of the group of patients treated surgically were correlated with histopathological findings. The MRI and DWI results of non-surgical cases were correlated with the results of clinical, laboratory and other imaging studies. Comparison of the ADC value of normal and pathological tissues was carried out followed by a statistical analysis. Results There was a significant difference between ADC values of malignant testicular lesions and normal testicular tissues as well as benign testicular lesions (P=0.000). At a cut-off ADC value of ≤0.99, it had a sensitivity of 93.3%, specificity of 90%, positive predictive value of 87.5%, and negative predictive value of 94.7% in the characterization of intratesticular masses. Conclusions Inclusion of DWI to routine MRI has a substantial value in improving diagnosis in patients with scrotal lesions and consequently can reduce unnecessary radical surgical procedures in these patients. PMID:26491491

  6. Meta-analysis of diffusion-weighted magnetic resonance imaging in identification of colorectal cancer

    PubMed Central

    Jia, Hongyuan; Ma, Xuelei; Zhao, Yang; Zhao, Jingyi; Liu, Rongjun; Chen, Zihang; Chen, Jinna; Huang, Jingwen; Li, Yanyan; Zhang, Jing; Wang, Feng

    2015-01-01

    Purpose: This meta-analysis aimed to evaluate the performance of diffusion-weighted magnetic resonance imaging (DWI) in identification of colorectal cancer. Methods: A systematic literature search was performed for studies that evaluated the diagnostic accuracy of DWI in identification of colorectal cancer. Methodological quality was assessed by Quality Assessment for Studies of Diagnostic Accuracy 2 (QUADAS 2) tool. After extracting data, we estimated the pooled sensitivity, specificity, likelihood ratios, and constructed summary receiver operating characteristics (SROC) curve. Results: Ten studies involving 367 malignant lesions and 178 benign lesions were considered eligible after full-text review. The pooled sensitivity and specificity were 0.95 (95% CI: 0.90-0.97) and 0.93 (95% CI: 0.85-0.97), respectively. Positive likelihood ratio and negative likelihood ratio were 12.8 (95% CI: 5.99-27.4) and 0.06 (95% CI: 0.03-0.11), respectively. The area under SROC curve was 0.98. Conclusions: Our meta-analysis indicates that DWI is a highly accurate diagnostic method in identification of colorectal cancer. PMID:26770325

  7. Hepatocellular Carcinoma and Diffusion-Weighted MRI: Detection and Evaluation of Treatment Response.

    PubMed

    Gluskin, Jill S; Chegai, Fabrizio; Monti, Serena; Squillaci, Ettore; Mannelli, Lorenzo

    2016-01-01

    Differentiating between cancerous tissue and healthy liver parenchyma could represent a challenge with the only conventional Magnetic Resonance (MR) imaging. Diffusion weighted imaging (DWI) exploits different tissue characteristics to conventional Magnetic Resonance Imaging (MRI) sequences that enhance hepatocellular carcinoma (HCC) detection, characterization, and post-treatment evaluation. Detection of HCC is improved by DWI, infact this technology increases conspicuity of lesions that might otherwise not be identified due to obscuration by adjacent vessels or due to low contrast between the lesion and background liver. It is important to remember that DWI combined with contrast-enhanced MRI has higher sensitivity than DWI alone, and that some patients are not eligible for use of contrast on CT and MRI; in these patients DWI has a prominent role. MRI has advanced beyond structural anatomic imaging to now showing pathophysiologic processes. DWI is a promising way to characterize lesions utilizing the inherent contrast within the liver and has the benefit of not requiring contrast injection. DWI improves detection and characterization of HCC. Proposed clinical uses for DWI include: assessing prognosis, predicting response, monitoring response to therapy, and distinguishing tumor recurrence from treatment effect. Ideally, DWI will help risk stratify patients and will participate in prognostic modeling. PMID:27471573

  8. Usefulness of Diffusion-Weighted Imaging in the Localization of Prostate Cancer

    SciTech Connect

    Kajihara, Hiroo; Hayashida, Yoshiko; Murakami, Ryuji Katahira, Kazuhiro; Nishimura, Ryuichi; Hamada, Yasuyuki; Kitani, Kousuke; Kitaoka, Mitsuhiko; Suzuki, Yasuko; Kitajima, Mika; Hirai, Toshinori; Morishita, Shoji; Awai, Kazuo; Yamashita, Yasuyuki

    2009-06-01

    Purpose: Advances in high-precision radiation therapy techniques for patients with prostate cancer permit selective escalation of the radiation dose delivered to the dominant intraprostatic lesion and improve the therapeutic ratio. We evaluated the value of diffusion-weighted imaging (DWI) for dominant intraprostatic lesion assessment. Methods and Materials: The study population consisted of 23 patients with early prostate cancer. Before undergoing total prostatectomy, they were evaluated by means of magnetic resonance imaging, including DWI. T2-weighted imaging (T2WI) with and without DWI were retrospectively assessed by six independent observers. Imaging findings were compared with pathologic results from whole prostate specimens on a lesion-by-lesion basis. Results: Pathologic study identified 43 lesions in 23 patients. On magnetic resonance imaging, the six observers correctly identified 11-22 of 43 lesions (sensitivity, 26-51%) on T2WI alone and 20-31 (sensitivity, 47-72%) on T2WI plus DWI. Positive predictive values were 42-73% on T2WI alone and 58-80% on T2WI plus DWI. For all observers, detection was higher on combined T2WI and DWI than on T2WI alone. Conclusion: Because the addition of DWI to T2WI improves the detectability of prostate cancer, DWI may offer a promising new approach for radiation therapy planning.

  9. Investigation of vibration-induced artifact in clinical diffusion-weighted imaging of pediatric subjects.

    PubMed

    Berl, Madison M; Walker, Lindsay; Modi, Pooja; Irfanoglu, M Okan; Sarlls, Joelle E; Nayak, Amritha; Pierpaoli, Carlo

    2015-12-01

    It has been reported that mechanical vibrations of the magnetic resonance imaging scanner could produce spurious signal dropouts in diffusion-weighted images resulting in artifactual anisotropy in certain regions of the brain with red appearance in the Directionally Encoded Color maps. We performed a review of the frequency of this artifact across pediatric studies, noting differences by scanner manufacturer, acquisition protocol, as well as weight and position of the subject. We also evaluated the ability of automated and quantitative methods to detect this artifact. We found that the artifact may be present in over 50% of data in certain protocols and is not limited to one scanner manufacturer. While a specific scanner had the highest incidence, low body weight and positioning were also associated with appearance of the artifact for both scanner types evaluated, making children potentially more susceptible than adults. Visual inspection remains the best method for artifact identification. Software for automated detection showed very low sensitivity (10%). The artifact may present inconsistently in longitudinal studies. We discuss a published case report that has been widely cited and used as evidence to set policy about diagnostic criteria for determining vegetative state. That report attributed longitudinal changes in anisotropy to white matter plasticity without considering the possibility that the changes were caused by this artifact. Our study underscores the need to check for the presence of this artifact in clinical studies, analyzes circumstances for when it may be more likely to occur, and suggests simple strategies to identify and potentially avoid its effects. PMID:26350492

  10. Hepatocellular Carcinoma and Diffusion-Weighted MRI: Detection and Evaluation of Treatment Response

    PubMed Central

    Gluskin, Jill S; Chegai, Fabrizio; Monti, Serena; Squillaci, Ettore; Mannelli, Lorenzo

    2016-01-01

    Differentiating between cancerous tissue and healthy liver parenchyma could represent a challenge with the only conventional Magnetic Resonance (MR) imaging. Diffusion weighted imaging (DWI) exploits different tissue characteristics to conventional Magnetic Resonance Imaging (MRI) sequences that enhance hepatocellular carcinoma (HCC) detection, characterization, and post-treatment evaluation. Detection of HCC is improved by DWI, infact this technology increases conspicuity of lesions that might otherwise not be identified due to obscuration by adjacent vessels or due to low contrast between the lesion and background liver. It is important to remember that DWI combined with contrast-enhanced MRI has higher sensitivity than DWI alone, and that some patients are not eligible for use of contrast on CT and MRI; in these patients DWI has a prominent role. MRI has advanced beyond structural anatomic imaging to now showing pathophysiologic processes. DWI is a promising way to characterize lesions utilizing the inherent contrast within the liver and has the benefit of not requiring contrast injection. DWI improves detection and characterization of HCC. Proposed clinical uses for DWI include: assessing prognosis, predicting response, monitoring response to therapy, and distinguishing tumor recurrence from treatment effect. Ideally, DWI will help risk stratify patients and will participate in prognostic modeling. PMID:27471573

  11. Robust optimal design of diffusion-weighted magnetic resonance experiments for skin microcirculation

    NASA Astrophysics Data System (ADS)

    Choi, J.; Raguin, L. G.

    2010-10-01

    Skin microcirculation plays an important role in several diseases including chronic venous insufficiency and diabetes. Magnetic resonance (MR) has the potential to provide quantitative information and a better penetration depth compared with other non-invasive methods such as laser Doppler flowmetry or optical coherence tomography. The continuous progress in hardware resulting in higher sensitivity must be coupled with advances in data acquisition schemes. In this article, we first introduce a physical model for quantifying skin microcirculation using diffusion-weighted MR (DWMR) based on an effective dispersion model for skin leading to a q-space model of the DWMR complex signal, and then design the corresponding robust optimal experiments. The resulting robust optimal DWMR protocols improve the worst-case quality of parameter estimates using nonlinear least squares optimization by exploiting available a priori knowledge of model parameters. Hence, our approach optimizes the gradient strengths and directions used in DWMR experiments to robustly minimize the size of the parameter estimation error with respect to model parameter uncertainty. Numerical evaluations are presented to demonstrate the effectiveness of our approach as compared to conventional DWMR protocols.

  12. Evaluation of three inverse problem models to quantify skin microcirculation using diffusion-weighted MRI

    NASA Astrophysics Data System (ADS)

    Cordier, G.; Choi, J.; Raguin, L. G.

    2008-11-01

    Skin microcirculation plays an important role in diseases such as chronic venous insufficiency and diabetes. Magnetic resonance imaging (MRI) can provide quantitative information with a better penetration depth than other noninvasive methods, such as laser Doppler flowmetry or optical coherence tomography. Moreover, successful MRI skin studies have recently been reported. In this article, we investigate three potential inverse models to quantify skin microcirculation using diffusion-weighted MRI (DWI), also known as q-space MRI. The model parameters are estimated based on nonlinear least-squares (NLS). For each of the three models, an optimal DWI sampling scheme is proposed based on D-optimality in order to minimize the size of the confidence region of the NLS estimates and thus the effect of the experimental noise inherent to DWI. The resulting covariance matrices of the NLS estimates are predicted by asymptotic normality and compared to the ones computed by Monte-Carlo simulations. Our numerical results demonstrate the effectiveness of the proposed models and corresponding DWI sampling schemes as compared to conventional approaches.

  13. Characterization and Correction of Geometric Distortions in 814 Diffusion Weighted Images

    PubMed Central

    Treiber, Jeffrey Mark; White, Nathan S.; Steed, Tyler Christian; Bartsch, Hauke; Holland, Dominic; Farid, Nikdokht; McDonald, Carrie R.; Carter, Bob S.

    2016-01-01

    Introduction Diffusion Weighted Imaging (DWI), which is based on Echo Planar Imaging (EPI) protocols, is becoming increasingly important for neurosurgical applications. However, its use in this context is limited in part by significant spatial distortion inherent to EPI. Method We evaluated an efficient algorithm for EPI distortion correction (EPIC) across 814 DWI scans from 250 brain tumor patients and quantified the magnitude of geometric distortion for whole brain and multiple brain regions. Results Evaluation of the algorithm’s performance revealed significantly higher mutual information between T1-weighted pre-contrast images and corrected b = 0 images than the uncorrected b = 0 images (p < 0.001). The distortion magnitude across all voxels revealed a median EPI distortion effect of 2.1 mm, ranging from 1.2 mm to 5.9 mm, the 5th and 95th percentile, respectively. Regions adjacent to bone-air interfaces, such as the orbitofrontal cortex, temporal poles, and brain stem, were the regions most severely affected by DWI distortion. Conclusion Using EPIC to estimate the degree of distortion in 814 DWI brain tumor images enabled the creation of a topographic atlas of DWI distortion across the brain. The degree of displacement of tumors boundaries in uncorrected images is severe but can be corrected for using EPIC. Our results support the use of distortion correction to ensure accurate and careful application of DWI to neurosurgical practice. PMID:27027775

  14. Secondary neurolymphomatosis detected by whole-body diffusion-weighted magnetic resonance imaging: a case report.

    PubMed

    Tanaka, Hiroaki; Yoshino, Kazuhiro; Sakaida, Emiko; Hashimoto, Shinichiro; Takeda, Yusuke; Kawajiri, Chika; Takagi, Toshiyuki; Nakaseko, Chiaki

    2013-01-01

    Neurolymphomatosis (NL) is a rare clinical entity defined as peripheral nervous system infiltration by lymphoma. The diagnosis is difficult and often elusive. Whole-body diffusion-weighted magnetic resonance imaging (DW MRI) was developed to enhance the detection of vaguely delineated tumors. Here, we describe the case of a 71-year-old male with secondary NL of diffuse large B-cell lymphoma (DLBCL) that was successfully detected by whole-body DW MRI. The patient was diagnosed with DLBCL extending from the ethmoidal sinus to the nasal cavity, orbital cavity, and anterior cranial fossa. Although he was administered R-THP-COP chemotherapy and the tumor remarkably decreased in size, he developed painful paresthesia and weakness in the left upper and bilateral lower extremities during treatment. Because lymphoma cells were detected in his spinal fluid, high-dose methotrexate (MTX) and weekly intrathecal MTX and cytarabine injections were administered. Test results for lymphoma cells in the spinal fluid became negative ; however, the neurological disorders progressed. Whole-body DW MRI was performed as whole-body screening and could localize NL at the left cervical and bilateral lumbar nerve roots. Both cervical spine plain MRI and enhanced computed tomography performed around the same time could not detect the cervical lesion. Our case report suggests that whole-body DW MRI is a useful diagnostic imaging procedure, especially as whole-body screening in facilities where PET/CT is not available. PMID:24369224

  15. Facies Analysis and b-Value for Operationally Induced Microseismicity

    NASA Astrophysics Data System (ADS)

    Eaton, D. W. S.; Davidsen, J.; Maghsoudi, S.

    2015-12-01

    Operationally induced microseismicity reveals brittle failure processes that occur during hydraulic fracturing stimulation of a rockmass. The b-value of the magnitude-frequency distribution is commonly used to characterize the relative abundance of high- to low-magnitude events. In contrast to earthquake fault systems with b ~ 1, microseismicity that is directly associated with hydraulic fracturing is typically characterized by b > 1.5. Recent studies show that such unusually high b-values may be primarily controlled by scaling properties of mechanical bed thickness within the treatment zone, since the occurrence of fracture arrest at bedding boundaries gives rise to stratabound fracture networks. Stress variations also influence the b-value. These concepts provide a framework for microseismic facies analysis, a novel approach for interpretation of microseismicity that facilitates delineation of lithofacies units and stress compartments for characterization of unconventional reservoirs. Microseismic facies units are recognized on the basis of clustering analysis and recognition of distinct sets of microseismic attributes, which include b-value (and other magnitude statistics), duration, transience, seismic moment density and seismic moment release rate in addition to commonly reported characteristics of azimuth and dimensions. A case study is presented, in which microseismic facies analysis is applied to characterize an unconventional reservoir.

  16. Acoustic Emission, b-values and Foliation Plane Anisotropy

    NASA Astrophysics Data System (ADS)

    Sehizadeh, Mahdi; Nasseri, Mohammad H.; Ye, Sheng; Young, R. Paul

    2016-04-01

    The b-value and D-value are two parameters related to size and distance distribution of earthquakes. There are many different factors affecting b-value such as stress state, thermal gradients, focal mechanism and heterogeneity. For example, the literature shows that the b-value changes systematically with respect to the focal mechanism. In laboratory experiments, foliation planes introduce a weakness in samples and can be considered as a potential for rupture or pre-existing faults, so they may exhibit similar relationships. The D-value defines the degree of clustering of earthquakes and would be expected to have a defined relationship with respect to the anisotropy. Using a unique facility in the Rock Fracture Dynamics laboratory at the University of Toronto, three sets of polyaxial experiments have been performed on cubic samples with foliation planes systematically oriented at different angles to the principal stress direction. During these tests, samples were loaded under controlled true-triaxial stress conditions until they failed or had severe damage and acoustic emission events were recorded using 18 sensors around the samples. The paper describes how the combination of stress state and foliation planes affects the b-value and D-value under laboratory conditions.

  17. The value of diffusion-weighted MRI in the diagnosis of malignant and benign urinary bladder lesions

    PubMed Central

    Avcu, S; Koseoglu, M N; Ceylan, K; Dbulutand, M; Unal, O

    2011-01-01

    Objectives To investigate the role of diffusion-weighted MRI (DWI) in the diagnosis of urinary bladder (UB) tumours by means of measuring apparent diffusion coefficient (ADC) values. Methods A total of 83 people aged between 18 and 86 years were included in the study: 63 patients with UB pathology (46 malignant, 17 benign) constituted the case group; 20 individuals without any UB pathology constituted the control group. DWI was applied to all individuals. The ADC values were measured based on the tissue of the UB mass entities and normal UB wall in the control group. Results The mean ADC value in the UB carcinoma group was significantly lower than that in the control group: 1.0684 ± 0.26 × 10−3 mm2 s–1 and 2.010 ± 0.11 × 10−3 mm2 s–1, respectively (p<0.01). There was a significant difference among the mean ADC values of different grades of malignant tumours, corresponding to 0.9185 ± 0.20 mm2 s–1 and 1.281 ± 0.18 mm2 s–1 in high-grade and low-grade malignant UB carcinomas, respectively (p<0.01). The ADC value in the carcinoma group was significantly lower than that in the benign lesion group: 1.0684 ± 0.26 × 10−3 mm2 s–1 and 1.803 ± 0.19 × 10−3 mm2 s–1, respectively (p<0.01). All 46 malignant lesions displayed a restriction in diffusion; 4 of the 17 benign lesions displayed a mild restriction in diffusion. The sensitivity, specificity and accuracy of DWI in the diagnosis of malignant UB lesions was 100%, 76.5% and 93.65%, respectively. Conclusion DWI can be beneficial in the differentiation of benign and malignant UB lesions, as well as of high-grade and low-grade UB carcinomas, using quantitative ADC measurements. PMID:21224296

  18. Role of Diffusion-Weighted Magnetic Resonance Imaging in Predicting Sensitivity to Chemoradiotherapy in Muscle-Invasive Bladder Cancer

    SciTech Connect

    Yoshida, Soichiro; Koga, Fumitaka; Kobayashi, Shuichiro; Ishii, Chikako; Tanaka, Hiroshi; Tanaka, Hajime; Komai, Yoshinobu; Saito, Kazutaka; Masuda, Hitoshi; Fujii, Yasuhisa; Kawakami, Satoru; Kihara, Kazunori

    2012-05-01

    Purpose: In chemoradiation (CRT)-based bladder-sparing approaches for muscle invasive bladder cancer (MIBC), patients who respond favorably to induction CRT enjoy the benefits of bladder preservation, whereas nonresponders do not. Thus, accurate prediction of CRT sensitivity would optimize patient selection for bladder-sparing protocols. Diffusion-weighted MRI (DW-MRI) is a functional imaging technique that quantifies the diffusion of water molecules in a noninvasive manner. We investigated whether DW-MRI predicts CRT sensitivity of MIBC. Methods and Materials: The study cohort consisted of 23 MIBC patients (cT2/T3 = 7/16) who underwent induction CRT consisting of radiotherapy to the small pelvis (40 Gy) with two cycles of cisplatin (20 mg/day for 5 days), followed by partial or radical cystectomy. All patients underwent DW-MRI before the initiation of treatment. Associations of apparent diffusion coefficient (ADC) values with CRT sensitivity were analyzed. The proliferative potential of MIBC was also assessed by analyzing the Ki-67 labeling index (LI) in pretherapeutic biopsy specimens. Results: Thirteen patients (57%) achieved pathologic complete response (pCR) to CRT. These CRT-sensitive MIBCs showed significantly lower ADC values (median, 0.63 Multiplication-Sign 10{sup -3} mm{sup 2}/s; range, 0.43-0.77) than CRT-resistant (no pCR) MIBCs (median, 0.84 Multiplication-Sign 10{sup -3} mm{sup 2}/s; range, 0.69-1.09; p = 0.0003). Multivariate analysis identified ADC value as the only significant and independent predictor of CRT sensitivity (p < 0.0001; odds ratio per 0.001 Multiplication-Sign 10{sup -3} mm{sup 2}/s increase, 1.03; 95% confidence interval, 1.01-1.08). With a cutoff ADC value at 0.74 Multiplication-Sign 10{sup -3} mm{sup 2}/s, sensitivity/specificity/accuracy in predicting CRT sensitivity was 92/90/91%. Ki-67 LI was significantly higher in CRT-sensitive MIBCs (p = 0.0005) and significantly and inversely correlated with ADC values ({rho} = -0.67, p = 0

  19. Quantification of fibrosis in infarcted swine hearts by ex vivo late gadolinium-enhancement and diffusion-weighted MRI methods

    NASA Astrophysics Data System (ADS)

    Pop, Mihaela; Ghugre, Nilesh R.; Ramanan, Venkat; Morikawa, Lily; Stanisz, Greg; Dick, Alexander J.; Wright, Graham A.

    2013-08-01

    Many have speculated that MRI signal characteristics can be used to identify regions of heterogeneous infarct associated with an arrhythmogenic substrate; however, direct evidence of this relationship is limited. The aim of this study was to demonstrate the remodelling characteristics of fibrosis by means of histology and high-resolution MR imaging. For this purpose, we performed whole-mount histology in heart samples (n = 9) collected from five swine at six weeks post-infarction and compared the extent of fibrosis in the infarcted areas delineated in these histological images with that obtained ex vivo by MRI using late gadolinium-enhancement (LGE) and diffusion-weighted imaging (DWI) methods. All MR images were obtained at a submillimetre resolution (i.e., voxel size of 0.6×0.6×1.2 mm3). Specifically, in the histology images, we differentiated moderate fibrosis (consisting of a mixture of viable and non-viable myocytes, known as border zone, BZ) from severe fibrosis (i.e., the dense scar). Correspondingly, tissue heterogeneities in the MR images were categorized by a Gaussian mixture model into healthy, BZ and scar. Our results showed that (a) both MRI methods were capable of qualitatively distinguishing sharp edges between dense scar and healthy tissue from regions of heterogeneous BZ; (b) the BZ and dense scar areas had intermediate-to-high increased values of signal intensity in the LGE images and of apparent diffusion coefficient in the DWI, respectively. In addition, as demonstrated by the Picrosirius Red and immunohistochemistry stains, the viable bundles in the BZ were clearly separated by thin collagen strands and had reduced expression of Cx43, whereas the core scar was composed of dense fibrosis. A quantitative analysis demonstrated that the comparison between BZ/scar extent in LGE and DWI to the corresponding areas identified in histology yielded very good correlations (i.e., for the scar identified by LGE, R2 was 0.96 compared to R2 = 0.93 for the

  20. The Value of Diffusion-Weighted Imaging in the Differential Diagnosis of Ovarian Lesions: A Meta-Analysis

    PubMed Central

    Shin, Yu Ri; Park, Chang Suk; Kim, Kijun

    2016-01-01

    Objectives The ability of contrast-enhanced MRI to distinguish between malignant and benign ovarian masses is limited. The aim of this meta-analysis is to evaluate the diagnostic performance of diffusion-weighted imaging (DWI) in differentiating malignant from benign ovarian masses. Methods A comprehensive literature search was performed in several authoritative databases to identify relevant articles. The weighted mean difference (WMD) and corresponding 95% confidence interval (95% CI) were calculated. We also used subgroup analysis to analyze study heterogeneity, and evaluated publication bias. Results The meta-analysis is based on 21 studies, which reported the findings for 731 malignant and 918 benign ovarian masses. There was no significant difference in apparent diffusion coefficient (ADC) values for DWI between benign and malignant lesions (WMD = 0.22, 95% CI = -0.02–0.47, p = 0.08). Subgroup analysis by benign tumor type revealed higher ADC values (or a trend toward higher values) for cysts, cystadenomas and other benign tumors compared to malignant masses (cyst: WMD = 0.54, 95% CI = -0.05–1.12, p = 0.07; cystadenoma: WMD = 0.73, 95% CI = 0.38–1.07, p < 0.0001; other benign tumor: WMD = 0.16, 95% CI = -0.13–0.46, p = 0.28). On the other hand, lower ADC values (or a trend toward lower values) were observed for endometrioma and teratoma compared to malignant masses (endometrioma: WMD = -0.09, 95% CI = -0.47–0.29, p = 0.64; teratoma: WMD = -0.49, 95% CI = -0.85–0.12, p = 0.009). Subgroup analysis by mass property revealed higher ADC values in cystic tumor types than in solid types for both benign and malignant tumors. Significant study heterogeneity was observed. There was no notable publication bias. Conclusions Quantitative DWI is not a reliable diagnostic method for differentiation between benign and malignant ovarian masses. This knowledge is essential in avoiding misdiagnosis of ovarian masses. PMID:26907919

  1. Quantitative Perfusion- and Diffusion-Weighted Magnetic Resonance Imaging of Gastrointestinal Cancers Treated With Multikinase Inhibitors: A Pilot Study

    PubMed Central

    Keene, Kimberly S.; Sarver, David B.; Lee, S. Kyle; Beasley, T. Mark; Morgan, Desiree E.; Posey, James A.

    2014-01-01

    ABSTRACT BACKGROUND: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI) are often used to detect the early response of solid tumors to an effective therapy. The early changes in intratumoral physiological parameters measured by DCE-MRI/DWI have been evaluated as surrogate biomarkers allowing a tailored treatment for the individual patient. METHODS: Patients with newly diagnosed, biopsy-proven, treatment-naïve gastrointestinal stromal tumor (GIST) or hepatocellular carcinoma (HCC) were enrolled prospectively after institutional review board (IRB)–approved informed consent (5 patients per tumor type). Patients with GIST were treated with sunitinib over 6 weeks. DCE-MRI/DWI was applied before therapy (baseline imaging) and at 2 and 6 weeks after therapy initiation. Patients with HCC were treated with radiation during the first 2 weeks and then with sorafenib for the next 6 weeks. DCE-MRI/DWI was applied in all patients with HCC before and after radiation therapy and at the end of sorafenib therapy. Tumor volume, perfusion parameters (Ktrans, the forward volume-transfer constant, and kep, the reverse reflux-rate constant) and the apparent diffusion coefficient (ADC) were measured. RESULTS: During 2 weeks of sunitinib therapy, GIST volume, Ktrans, and kep decreased 32 ± 13, 45 ± 24, and 42 ± 15%, respectively, whereas ADC increased 76 ± 24%. After 6 weeks of sunitinib therapy, GIST volume, Ktrans, and kep decreased 56 ± 7, 70 ± 7, and 50 ± 12%, respectively, whereas ADC increased 85 ± 33%. After completion of radiation therapy, HCC volume, Ktrans, and kep decreased 34 ± 14, 35 ± 12, and 4 ± 21%, respectively, but ADC increased 21 ± 9%. During the entire 10-week therapeutic period, HCC volume, Ktrans, and kep decreased 65 ± 15, 40 ± 9, and 26 ± 2%, respectively, whereas ADC increased 28 ± 10%. CONCLUSION: DCE-MRI/DWI can measure the perfusion and diffusion changes in GISTs or HCCs treated with

  2. Supratentorial and infratentorial damage in spinocerebellar ataxia 2: a diffusion-weighted MRI study.

    PubMed

    Salvatore, Elena; Tedeschi, Enrico; Mollica, Carmine; Vicidomini, Caterina; Varrone, Andrea; Coda, Anna Rita Daniela; Brunetti, Arturo; Salvatore, Marco; De Michele, Giuseppe; Filla, Alessandro; Pappatà, Sabina

    2014-05-01

    Spinocerebellar ataxia type 2 (SCA2) is an autosomal-dominant degenerative disorder that is neuropathologically characterized primarily by infratentorial damage, although less severe supratentorial involvement may contribute to the clinical manifestation. Diffusion-weighted imaging (DWI)-Magnetic Resonance Imaging (MRI) studies of SCA2 have enabled in vivo quantification of neurodegeneration in infratentorial regions, whereas supratentorial regions have been explored less thoroughly. We measured microstructural changes in both infratentorial and supratentorial regions in 13 SCA2 patients (9 men, 4 women; mean age, 50 ± 12 years) and 15 controls (10 men, 5 women; mean age, 49 ± 14 years) using DWI-MRI and correlated the DWI changes with disease severity and duration. Disease severity was evaluated using the International Cooperative Ataxia Rating Scale and the Inherited Ataxia Clinical Rating Scale. Cerebral diffusion trace ( D¯) values were generated, and regions of interest (ROIs) and voxel-based analysis with Statistical Parametric Mapping (SPM) were used for data analysis. In SCA2 patients, ROI analysis and SPM confirmed significant increases in D¯ values in the pons, cerebellar white matter (CWM) and middle cerebellar peduncles. Moreover, SPM analysis revealed increased D¯ values in the right thalamus, bilateral temporal cortex/white matter, and motor cortex/pyramidal tract regions. Increased diffusivity in the frontal white matter (FWM) and the CWM was significantly correlated with ataxia severity. DWI-MRI revealed that both infratentorial and supratentorial microstructural changes may characterize SCA2 patients in the course of the disease and might contribute to the severity of the symptoms. PMID:24375449

  3. Clinically Confirmed Stroke With Negative Diffusion-Weighted Imaging Magnetic Resonance Imaging

    PubMed Central

    Makin, Stephen D.J.; Doubal, Fergus N.; Dennis, Martin S.

    2015-01-01

    Background and Purpose— We sought to establish whether the presence (versus absence) of a lesion on magnetic resonance imaging (MRI) with diffusion weighting (DWI-MRI) at presentation with acute stroke is associated with worse clinical outcomes at 1 year. Methods— We recruited consecutive patients with a nondisabling ischemic stroke and performed DWI-MRI. Patients were followed up at 1 year to establish stroke recurrence (clinical or on MRI), cognitive impairment (Addenbrooke Cognitive Assessment Revised,<88) and modified Rankin Scale. Results— A median of 4 days post stroke, one third (76/264; 29%) of patients did not have a DWI lesion (95% confidence interval, 23%–35%). There was no statistically significant difference between those with and without a DWI lesion with respect to age or vascular risk factors. Patients without a lesion were more likely to be women or have previous stroke. At 1 year, 11 of 76 (14%) patients with a DWI-negative index stroke had a clinical diagnosis of recurrent stroke or transient ischemic attack, 33% had cognitive impairment (Addenbrooke Cognitive Assessment Revised <88), and 40% still had modified Rankin Scale >1, no different from DWI-positive patients; DWI-positive patients were more likely to have a new lesion on MRI (14%), symptomatic or asymptomatic, than DWI-negative patients (2%; P=0.02). Our data were consistent with 6 other studies (total n=976), pooled proportion of DWI-negative patients was 21% (95% confidence interval, 12%–32%). Conclusions— Nearly one third of patients with nondisabling stroke do not have a relevant lesion on acute DWI-MRI. Patients with negative DWI-MRI had no better prognosis than patients with a lesion. DWI-negative stroke patients should receive secondary prevention. PMID:26419965

  4. Diffusion-weighted imaging in cancer: physical foundations and applications of restriction spectrum imaging.

    PubMed

    White, Nathan S; McDonald, Carrie; McDonald, Carrie R; Farid, Niky; Kuperman, Josh; Karow, David; Schenker-Ahmed, Natalie M; Bartsch, Hauke; Rakow-Penner, Rebecca; Holland, Dominic; Shabaik, Ahmed; Bjørnerud, Atle; Hope, Tuva; Hattangadi-Gluth, Jona; Liss, Michael; Parsons, J Kellogg; Chen, Clark C; Raman, Steve; Margolis, Daniel; Reiter, Robert E; Marks, Leonard; Kesari, Santosh; Mundt, Arno J; Kane, Christopher J; Kaine, Christopher J; Carter, Bob S; Bradley, William G; Dale, Anders M

    2014-09-01

    Diffusion-weighted imaging (DWI) has been at the forefront of cancer imaging since the early 2000s. Before its application in clinical oncology, this powerful technique had already achieved widespread recognition due to its utility in the diagnosis of cerebral infarction. Following this initial success, the ability of DWI to detect inherent tissue contrast began to be exploited in the field of oncology. Although the initial oncologic applications for tumor detection and characterization, assessing treatment response, and predicting survival were primarily in the field of neurooncology, the scope of DWI has since broadened to include oncologic imaging of the prostate gland, breast, and liver. Despite its growing success and application, misconceptions about the underlying physical basis of the DWI signal exist among researchers and clinicians alike. In this review, we provide a detailed explanation of the biophysical basis of diffusion contrast, emphasizing the difference between hindered and restricted diffusion, and elucidating how diffusion parameters in tissue are derived from the measurements via the diffusion model. We describe one advanced DWI modeling technique, called restriction spectrum imaging (RSI). This technique offers a more direct in vivo measure of tumor cells, due to its ability to distinguish separable pools of water within tissue based on their intrinsic diffusion characteristics. Using RSI as an example, we then highlight the ability of advanced DWI techniques to address key clinical challenges in neurooncology, including improved tumor conspicuity, distinguishing actual response to therapy from pseudoresponse, and delineation of white matter tracts in regions of peritumoral edema. We also discuss how RSI, combined with new methods for correction of spatial distortions inherent in diffusion MRI scans, may enable more precise spatial targeting of lesions, with implications for radiation oncology and surgical planning. See all articles in this

  5. Prediction of Selective Serotonin Reuptake Inhibitor Response Using Diffusion-Weighted MRI

    PubMed Central

    DeLorenzo, Christine; Delaparte, Lauren; Thapa-Chhetry, Binod; Miller, Jeffrey M.; Mann, J. John; Parsey, Ramin V.

    2013-01-01

    Pre-treatment differences in serotonergic binding between those who remit to antidepressant treatment and those who do not have been found using Positron Emission Tomography (PET). To investigate these differences, an exploratory study was performed using a second imaging modality, diffusion-weighted MRI (DW-MRI). Eighteen antidepressant-free subjects with Major Depressive Disorder received a 25-direction DW-MRI scan prior to 8 weeks of selective serotonin reuptake inhibitor treatment. Probabilistic tractography was performed between the midbrain/raphe and two target regions implicated in depression pathophysiology (amygdala and hippocampus). Average fractional anisotropy (FA) within the derived tracts was compared between SSRI remitters and non-remitters, and correlation between pre-treatment FA values and SSRI treatment outcome was assessed. Results indicate that average FA in DW-MRI-derived tracts to the right amygdala was significantly lower in non-remitters (0.55 ± 0.04) than remitters (0.61 ± 0.04, p < 0.01). In addition, there was a significant correlation between average FA in tracts to the right amygdala and SSRI treatment response. These relationships were found at a trend level when using the left amygdala as a tractography target. No significant differences were observed when using the hippocampus as target. These regional differences, consistent with previous PET findings, suggest that the integrity and/or number of white matter fibers terminating in the right amygdala may be compromised in SSRI non-remitters. Further, this study points to the benefits of multimodal imaging and suggests that DW-MRI may provide a pre-treatment signature of SSRI depression remission at 8 weeks. PMID:23508528

  6. Spatially-constrained probability distribution model of incoherent motion (SPIM) for abdominal diffusion-weighted MRI.

    PubMed

    Kurugol, Sila; Freiman, Moti; Afacan, Onur; Perez-Rossello, Jeannette M; Callahan, Michael J; Warfield, Simon K

    2016-08-01

    Quantitative diffusion-weighted MR imaging (DW-MRI) of the body enables characterization of the tissue microenvironment by measuring variations in the mobility of water molecules. The diffusion signal decay model parameters are increasingly used to evaluate various diseases of abdominal organs such as the liver and spleen. However, previous signal decay models (i.e., mono-exponential, bi-exponential intra-voxel incoherent motion (IVIM) and stretched exponential models) only provide insight into the average of the distribution of the signal decay rather than explicitly describe the entire range of diffusion scales. In this work, we propose a probability distribution model of incoherent motion that uses a mixture of Gamma distributions to fully characterize the multi-scale nature of diffusion within a voxel. Further, we improve the robustness of the distribution parameter estimates by integrating spatial homogeneity prior into the probability distribution model of incoherent motion (SPIM) and by using the fusion bootstrap solver (FBM) to estimate the model parameters. We evaluated the improvement in quantitative DW-MRI analysis achieved with the SPIM model in terms of accuracy, precision and reproducibility of parameter estimation in both simulated data and in 68 abdominal in-vivo DW-MRIs. Our results show that the SPIM model not only substantially reduced parameter estimation errors by up to 26%; it also significantly improved the robustness of the parameter estimates (paired Student's t-test, p < 0.0001) by reducing the coefficient of variation (CV) of estimated parameters compared to those produced by previous models. In addition, the SPIM model improves the parameter estimates reproducibility for both intra- (up to 47%) and inter-session (up to 30%) estimates compared to those generated by previous models. Thus, the SPIM model has the potential to improve accuracy, precision and robustness of quantitative abdominal DW-MRI analysis for clinical applications. PMID

  7. Diffusion-weighted imaging in cancer: Physical foundations and applications of Restriction Spectrum Imaging

    PubMed Central

    White, Nathan S.; McDonald, Carrie; Farid, Niky; Kuperman, Josh; Karow, David; Schenker-Ahmed, Natalie M.; Bartsch, Hauke; Rakow-Penner, Rebecca; Holland, Dominic; Shabaik, Ahmed; Bjørnerud, Atle; Hope, Tuva; Hattangadi-Gluth, Jona; Liss, Michael; Parsons, J. Kellogg; Chen, Clark C.; Raman, Steve; Margolis, Daniel; Reiter, Robert E.; Marks, Leonard; Kesari, Santosh; Mundt, Arno J.; Kane, Chris J.; Carter, Bob S.; Bradley, William G.; Dale, Anders M.

    2014-01-01

    Diffusion weighted imaging (DWI) has been at the forefront of cancer imaging since the early 2000’s. Prior to its application in clinical oncology, this powerful technique had already achieved widespread recognition due to its utility in the diagnosis of cerebral infarction. Following this initial success, the ability of DWI to detect inherent tissue contrast began to be exploited in the field of oncology. Although the initial oncologic applications for tumor detection and characterization, assessing treatment response, and predicting survival were primarily in the field of neuro-oncology, the scope of DWI has since broadened to include oncologic imaging of the prostate gland, breast, and liver. Despite its growing success and application, misconceptions as to the underlying physical basis of the DWI signal exist among researchers and clinicians alike. In this review, we provide a detailed explanation of the biophysical basis of diffusion contrast, emphasizing the difference between hindered and restricted diffusion, and elucidating how diffusion parameters in tissue are derived from the measurements via the diffusion model. We describe one advanced DWI modeling technique, called Restriction Spectrum Imaging (RSI). This technique offers a more direct in vivo measure of tumor cells, due to its ability to distinguish separable pools of water within tissue based on their intrinsic diffusion characteristics. Using RSI as an example, we then highlight the ability of advanced DWI techniques to address key clinical challenges in neuro-oncology, including improved tumor conspicuity, distinguishing actual response to therapy from pseudoresponse, and delineation of white matter tracts in regions of peritumoral edema. We also discuss how RSI, combined with new methods for correction of spatial distortions inherent diffusion MRI scans, may enable more precise spatial targeting of lesions, with implications for radiation oncology, and surgical planning. PMID:25183788

  8. Implementation and assessment of diffusion-weighted partial Fourier readout-segmented echo-planar imaging.

    PubMed

    Frost, Robert; Porter, David A; Miller, Karla L; Jezzard, Peter

    2012-08-01

    Single-shot echo-planar imaging has been used widely in diffusion magnetic resonance imaging due to the difficulties in correcting motion-induced phase corruption in multishot data. Readout-segmented EPI has addressed the multishot problem by introducing a two-dimensional nonlinear navigator correction with online reacquisition of uncorrectable data to enable acquisition of high-resolution diffusion data with reduced susceptibility artifact and T*(2) blurring. The primary shortcoming of readout-segmented EPI in its current form is its long acquisition time (longer than similar resolution single-shot echo-planar imaging protocols by approximately the number of readout segments), which limits the number of diffusion directions. By omitting readout segments at one side of k-space and using partial Fourier reconstruction, readout-segmented EPI imaging times could be reduced. In this study, the effects of homodyne and projection onto convex sets reconstructions on estimates of the fractional anisotropy, mean diffusivity, and diffusion orientation in fiber tracts and raw T(2)- and trace-weighted signal are compared, along with signal-to-noise ratio results. It is found that projections onto convex sets reconstruction with 3/5 segments in a 2 mm isotropic diffusion tensor image acquisition and 9/13 segments in a 0.9 × 0.9 × 4.0 mm(3) diffusion-weighted image acquisition provide good fidelity relative to the full k-space parameters. This allows application of readout-segmented EPI to tractography studies, and clinical stroke and oncology protocols. PMID:22535706

  9. Optimal Short-Time Acquisition Schemes in High Angular Resolution Diffusion-Weighted Imaging

    PubMed Central

    Prčkovska, V.; Achterberg, H. C.; Bastiani, M.; Pullens, P.; Balmashnova, E.; ter Haar Romeny, B. M.; Vilanova, A.; Roebroeck, A.

    2013-01-01

    This work investigates the possibilities of applying high-angular-resolution-diffusion-imaging- (HARDI-) based methods in a clinical setting by investigating the performance of non-Gaussian diffusion probability density function (PDF) estimation for a range of b-values and diffusion gradient direction tables. It does so at realistic SNR levels achievable in limited time on a high-performance 3T system for the whole human brain in vivo. We use both computational simulations and in vivo brain scans to quantify the angular resolution of two selected reconstruction methods: Q-ball imaging and the diffusion orientation transform. We propose a new analytical solution to the ODF derived from the DOT. Both techniques are analytical decomposition approaches that require identical acquisition and modest postprocessing times and, given the proposed modifications of the DOT, can be analyzed in a similar fashion. We find that an optimal HARDI protocol given a stringent time constraint (<10 min) combines a moderate b-value (around 2000 s/mm2) with a relatively low number of acquired directions (>48). Our findings generalize to other methods and additional improvements in MR acquisition techniques. PMID:23554808

  10. Diffusion weighted imaging for the differential diagnosis of benign vs. malignant ovarian neoplasms

    PubMed Central

    MENG, XIANG-FU; ZHU, SHI-CAI; SUN, SHAO-JUAN; GUO, JI-CAI; WANG, XUE

    2016-01-01

    In order to assess the diagnostic accuracy of diffusion weighted imaging (DWI) in differentiating between benign and malignant ovarian neoplasms, a systemic meta-analysis was conducted. Relevant studies were retrieved from scientific literature databases, including the PubMed, Wiley, EBSCO, Ovid, Web of Science, Wanfang, China National Knowledge Infrastructure and VIP databases. Following a multi-step screening and study selection process, the relevant data was extracted for use in the present study. Statistical analyses were performed using Meta-disc software version 1.4 and STATA statistical software version 12.0. A total of 285 articles were retrieved from the database searches. Following a careful screening process, 10 case-control studies were selected for the present meta-analysis. The 10 studies investigated the efficacy of DWI in diagnosing ovarian neoplasms, and included a combined total of 1,159 subjects, of which 559 patients had malignant lesions and 600 had benign lesions. The results showed that the pooled sensitivity, pooled specificity, pooled positive likelihood ratio, pooled negative likelihood ratio, pooled diagnostic odds ratio (DOR) and area under the curve of the summary receiver operating characteristics curve of DWI for differentiating between benign and malignant ovarian neoplasms were 0.93, 0.89, 7.58, 0.10, 85.33 and 0.95, respectively. A subgroup analysis based on ethnicity revealed no significant difference between Asians and Caucasians. Another subgroup analysis by magnetic resonance imaging (MRI) type showed that the DORs for GE Healthcare Life Sciences and Siemens AG machines were 100.76 [95% confidence interval (CI), 65.28–155.53] and 30.85 (95% CI, 10.40–91.53), respectively; this indicates that the diagnostic efficiency of the GE Healthcare Life Sciences MRI is superior compared with the Siemens AG MRI. The DWI demonstrated an excellent diagnostic performance in discriminating between benign and malignant ovarian neoplasms

  11. Diffusion Weighted Magnetic Resonance Imaging Assessment of Blood Flow in the Microvasculature of Abdominal Organs

    NASA Astrophysics Data System (ADS)

    Truica, Loredana Sorina

    In this thesis, water diffusion in human liver and placenta is studied using diffusion weighted magnetic resonance imaging. For short, randomly oriented vascular segments, intravascular water motion is diffusion-like. For tissues with large vascular compartments the diffusion decay is bi-exponential with one component corresponding to diffusing water and the other to water in the microvasculature. This model, known as the intravoxel incoherent motion (IVIM) model, is seldom used with abdominal organs because of motion artifacts. This limitation was overcome for the experiments reported here by introducing: 1) parallel imaging, 2) navigator echo respiratory triggering (NRT), 3) a double echo diffusion sequence that inherently compensates for eddy current effects, 4) SPAIR fat suppression and 5) a superior approach to image analysis. In particular, the use of NRT allowed us to use a free breathing protocol instead of the previously required breath hold protocol. The resulting DWI images were of high quality and motion artifact free. Diffusion decays were measured over a larger portion of the decay than had previously been reported and the results are considerably better than those previously reported. For both studies, reliable measurements of the diffusion coefficient (D), pseudo-diffusion coefficient (D) and perfusion fraction (f), were obtained using a region of interest analysis as well as a pixel-by-pixel approach. To within experimental error, all patients had the same values of D (1.10 mum 2/ms +/- 0.16 mum2/ms), D* (46 mum2/ms +/- 17 mum2/ms) and f (44.0% +/- 6.9%) in liver and D (1.8 mum 2/ms +/- 0.2 mum2/ms), D* (30 mum 2/ms +/- 12 mmu2/ms), and f (40% +/- 6%) in the placenta. No dependence on gestational age was found for the placental study. Parametric maps of f and D* were consistent with blood flow patterns in both systems. The model worked well for both investigated organs even though their anatomical structures are quite different. A method for

  12. Calculation methods for ventricular diffusion-weighted imaging thermometry: phantom and volunteer studies.

    PubMed

    Sakai, Koji; Yamada, Kei; Sugimoto, Naozo

    2012-02-01

    A method for the measurement of temperature in the lateral ventricle using diffusion-weighted imaging (DWI) has been proposed recently. This method uses predetermined arbitrary thresholds, but a more objective method of calculation would be useful. We therefore compared four different calculation methods, two of which were newly created and did not require predetermined thresholds. A rectangular polyethylene terephthalate bottle (8 × 10 × 28 cm(3)) was filled with heated water (35.0-38.8 °C) and used as a water phantom. The DWI data of 23 healthy subjects (aged 26-75 years; mean ± standard deviation, 50.13 ± 19.1 years) were used for this study. The temperature was calculated using the following equation: T(°C) = 2256.74/ln(4.39221/D) - 273.15, where D is the diffusion coefficient. The mean ventricular temperature was calculated by four methods: two thresholding methods and two histogram curve-fitting methods. As a reference, we used the temperature measured at the tympanic membrane, which is known to be approximately 1 °C lower than the brain temperature. The averaged differences in temperature between mercury thermometry and classical predetermined thresholding methods for the water phantom were 0.10 ± 0.42 and 0.05 ± 0.41 °C, respectively. The histogram curve-fitting methods, however, yielded temperatures a little lower (averaged differences of -0.24 ± 0.32 and -0.14 ± 0.31 °C, respectively) than mercury thermometry. There was very little difference in temperature between tympanic thermometry and classical predetermined thresholding methods (+0.01 and -0.07 °C, respectively). In humans, however, the histogram curve-fitting methods yielded temperatures approximately 1 °C higher (+1.04 °C and +1.36 °C, respectively), suggesting that temperatures measured in this way more closely approximate the true brain temperature. The histogram curve-fitting methods were more objective and better

  13. Modeling diffusion-weighted MRI as a spatially variant Gaussian mixture: Application to image denoising

    PubMed Central

    Gonzalez, Juan Eugenio Iglesias; Thompson, Paul M.; Zhao, Aishan; Tu, Zhuowen

    2011-01-01

    classification tasks. Conclusions: The presented spatially variant mixture model for diffusion MRI provides excellent denoising results at low signal-to-noise ratios. This makes it possible to restore data acquired with a fast (i.e., noisy) pulse sequence to acceptable noise levels. This is the case in diffusion MRI, where a large number of diffusion-weighted volumes have to be acquired under clinical time constraints. PMID:21859036

  14. A finite difference method with periodic boundary conditions for simulations of diffusion-weighted magnetic resonance experiments in tissue

    NASA Astrophysics Data System (ADS)

    Russell, Greg; Harkins, Kevin D.; Secomb, Timothy W.; Galons, Jean-Philippe; Trouard, Theodore P.

    2012-02-01

    A new finite difference (FD) method for calculating the time evolution of complex transverse magnetization in diffusion-weighted magnetic resonance imaging and spectroscopy experiments is described that incorporates periodic boundary conditions. The new FD method relaxes restrictions on the allowable time step size employed in modeling which can significantly reduce computation time for simulations of large physical extent and allow for more complex, physiologically relevant, geometries to be simulated.

  15. A Framework for Linear and Non-Linear Registration of Diffusion-Weighted MRIs Using Angular Interpolation

    PubMed Central

    Duarte-Carvajalino, Julio M.; Sapiro, Guillermo; Harel, Noam; Lenglet, Christophe

    2013-01-01

    Registration of diffusion-weighted magnetic resonance images (DW-MRIs) is a key step for population studies, or construction of brain atlases, among other important tasks. Given the high dimensionality of the data, registration is usually performed by relying on scalar representative images, such as the fractional anisotropy (FA) and non-diffusion-weighted (b0) images, thereby ignoring much of the directional information conveyed by DW-MR datasets itself. Alternatively, model-based registration algorithms have been proposed to exploit information on the preferred fiber orientation(s) at each voxel. Models such as the diffusion tensor or orientation distribution function (ODF) have been used for this purpose. Tensor-based registration methods rely on a model that does not completely capture the information contained in DW-MRIs, and largely depends on the accurate estimation of tensors. ODF-based approaches are more recent and computationally challenging, but also better describe complex fiber configurations thereby potentially improving the accuracy of DW-MRI registration. A new algorithm based on angular interpolation of the diffusion-weighted volumes was proposed for affine registration, and does not rely on any specific local diffusion model. In this work, we first extensively compare the performance of registration algorithms based on (i) angular interpolation, (ii) non-diffusion-weighted scalar volume (b0), and (iii) diffusion tensor image (DTI). Moreover, we generalize the concept of angular interpolation (AI) to non-linear image registration, and implement it in the FMRIB Software Library (FSL). We demonstrate that AI registration of DW-MRIs is a powerful alternative to volume and tensor-based approaches. In particular, we show that AI improves the registration accuracy in many cases over existing state-of-the-art algorithms, while providing registered raw DW-MRI data, which can be used for any subsequent analysis. PMID:23596381

  16. IVIM diffusion-weighted imaging of the liver at 3.0 T: Comparison with 1.5 T

    PubMed Central

    Cui, Yong; Dyvorne, Hadrien; Besa, Cecilia; Cooper, Nancy; Taouli, Bachir

    2015-01-01

    Purpose To compare intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) of the liver between 1.5 T and 3.0 T in terms of parameter quantification and inter-platform reproducibility. Materials and methods In this IRB approved prospective study, 19 subjects (17 patients with chronic liver disease and 2 healthy volunteers) underwent two repeat scans at 1.5 T and 3.0 T. Each scan included IVIM DWI using 16 b values from 0 to 800 s/mm2. A single observer measured IVIM parameters for each platform and estimated signal to noise ratio (eSNR) at b0, 200, 400 and 800 s/mm2. Wilcoxon paired tests were used to compare liver eSNR and IVIM parameters. Inter-platform reproducibility was assessed by calculating within-subject coefficient of variation (CV) and Bland–Altman limits of agreement. An ice water phantom was used to test ADC variability between the two MRI systems. Results The mean invitro difference in ADC between the two platforms was 6.8%. eSNR was significantly higher at 3.0T for all selected b values (p = 0.006–0.020), except for b0 (p = 0.239). Liver IVIM parameters were significantly different between 1.5 T and 3.0 T (p = 0.005–0.044), except for ADC (p = 0.748). The inter-platform reproducibility of true diffusion coefficient (D) and ADC were good, with mean CV of 10.9% and 11.1%, respectively. Perfusion fraction (PF) and pseudodiffusion coefficient (D*) showed more limited inter-platform reproducibility (mean CV of 22.6% for PF and 46.9% for D*). Conclusion Liver D and ADC values showed good reproducibility between 1.5 T and 3.0 T platforms; while there was more variability in PF, and large variability in D* parameters between the two platforms. These findings may have implications for drug trials assessing the role of IVIM DWI in tumor response and liver fibrosis. PMID:26393236

  17. Inter- and Intra-Observer Repeatability of Quantitative Whole-Body, Diffusion-Weighted Imaging (WBDWI) in Metastatic Bone Disease

    PubMed Central

    Blackledge, Matthew D.; Tunariu, Nina; Orton, Matthew R.; Padhani, Anwar R.; Collins, David J.; Leach, Martin O.; Koh, Dow-Mu

    2016-01-01

    Quantitative whole-body diffusion-weighted MRI (WB-DWI) is now possible using semi-automatic segmentation techniques. The method enables whole-body estimates of global Apparent Diffusion Coefficient (gADC) and total Diffusion Volume (tDV), both of which have demonstrated considerable utility for assessing treatment response in patients with bone metastases from primary prostate and breast cancers. Here we investigate the agreement (inter-observer repeatability) between two radiologists in their definition of Volumes Of Interest (VOIs) and subsequent assessment of tDV and gADC on an exploratory patient cohort of nine. Furthermore, each radiologist was asked to repeat his or her measurements on the same patient data sets one month later to identify the intra-observer repeatability of the technique. Using a Markov Chain Monte Carlo (MCMC) estimation method provided full posterior probabilities of repeatability measures along with maximum a-posteriori values and 95% confidence intervals. Our estimates of the inter-observer Intraclass Correlation Coefficient (ICCinter) for log-tDV and median gADC were 1.00 (0.97–1.00) and 0.99 (0.89–0.99) respectively, indicating excellent observer agreement for these metrics. Mean gADC values were found to have ICCinter = 0.97 (0.81–0.99) indicating a slight sensitivity to outliers in the derived distributions of gADC. Of the higher order gADC statistics, skewness was demonstrated to have good inter-user agreement with ICCinter = 0.99 (0.86–1.00), whereas gADC variance and kurtosis performed relatively poorly: 0.89 (0.39–0.97) and 0.96 (0.69–0.99) respectively. Estimates of intra-observer repeatability (ICCintra) demonstrated similar results: 0.99 (0.95–1.00) for log-tDV, 0.98 (0.89–0.99) and 0.97 (0.83–0.99) for median and mean gADC respectively, 0.64 (0.25–0.88) for gADC variance, 0.85 (0.57–0.95) for gADC skewness and 0.85 (0.57–0.95) for gADC kurtosis. Further investigation of two anomalous patient cases

  18. New Magnetic Resonance Imaging Index for Renal Fibrosis Assessment: A Comparison between Diffusion-Weighted Imaging and T1 Mapping with Histological Validation

    PubMed Central

    Friedli, I.; Crowe, L. A.; Berchtold, L.; Moll, S.; Hadaya, K.; de Perrot, T.; Vesin, C.; Martin, P.-Y.; de Seigneux, S.; Vallée, J.-P.

    2016-01-01

    A need exists to noninvasively assess renal interstitial fibrosis, a common process to all kidney diseases and predictive of renal prognosis. In this translational study, Magnetic Resonance Imaging (MRI) T1 mapping and a new segmented Diffusion-Weighted Imaging (DWI) technique, for Apparent Diffusion Coefficient (ADC), were first compared to renal fibrosis in two well-controlled animal models to assess detection limits. Validation against biopsy was then performed in 33 kidney allograft recipients (KARs). Predictive MRI indices, ΔT1 and ΔADC (defined as the cortico-medullary differences), were compared to histology. In rats, both T1 and ADC correlated well with fibrosis and inflammation showing a difference between normal and diseased kidneys. In KARs, MRI indices were not sensitive to interstitial inflammation. By contrast, ΔADC outperformed ΔT1 with a stronger negative correlation to fibrosis (R2 = 0.64 against R2 = 0.29 p < 0.001). ΔADC tends to negative values in KARs harboring cortical fibrosis of more than 40%. Using a discriminant analysis method, the ΔADC, as a marker to detect such level of fibrosis or higher, led to a specificity and sensitivity of 100% and 71%, respectively. This new index has potential for noninvasive assessment of fibrosis in the clinical setting. PMID:27439482

  19. Diffusion-weighted magnetic resonance imaging for prediction of tumor response to neoadjuvant chemoradiotherapy using irinotecan plus S-1 for rectal cancer

    PubMed Central

    DOI, HIROSHI; BEPPU, NAOHITO; KATO, TAKASHI; NODA, MASASHI; YANAGI, HIDENORI; TOMITA, NAOHIRO; KAMIKONYA, NORIHIKO; HIROTA, SHOZO

    2015-01-01

    The purpose of this study was to investigate the clinical value of diffusion-weighted (DW) magnetic resonance imaging (MRI) as a predictor of tumor response in patients receiving neoadjuvant chemoradiotherapy (NA-CRT) for rectal cancer (RC) through measurement of the apparent diffusion coefficient (ADC) value in each tumor. Neoadjuvant radiotherapy with a total dose of 45 Gy in 25 fractions was performed in all 16 patients with RC, combined with irinotecan and S-1. MRI was performed before and after NA-CRT. Multiple factors were assessed to predict the pathological response to NA-CRT. The pathological response rate was determined in 9 patients (56.3%). Statistical analyses indicated that the ADC value prior to NA-CRT was significantly lower in patients with a better response to NA-CRT (P=0.023). A cut-off value of 0.750×10−3 mm2/sec obtained by a receiver operating characteristic curve analysis indicated a sensitivity of 77.8% and specificity of 85.7% for pathological responders to NA-CRT. In addition, the patients with lower ADC values exhibited a greater pathological response to NA-CRT (P=0.041). In conclusion, the ADC value of MRI of RC patients treated with NA-CRT followed by surgery may provide valuable information to predict the response to NA-CRT. PMID:26623064

  20. Diffusion-weighted imaging for non-invasive and quantitative monitoring of bone marrow infiltration in patients with monoclonal plasma cell disease: a comparative study with histology.

    PubMed

    Hillengass, Jens; Bäuerle, Tobias; Bartl, Reiner; Andrulis, Mindaugas; McClanahan, Fabienne; Laun, Frederik B; Zechmann, Christian Martin; Shah, Rajiv; Wagner-Gund, Barbara; Simon, Dirk; Heiss, Christiane; Neben, Kai; Ho, Anthony D; Schlemmer, Heinz-Peter; Goldschmidt, Hartmut; Delorme, Stefan; Stieltjes, Bram

    2011-06-01

    Bone marrow plasma cell infiltration is a crucial parameter of disease activity in monoclonal plasma cell disorders. Until now, the only way to quantify such infiltration was bone marrow biopsy or aspiration. Diffusion-weighted imaging (DWI) is a magnetic resonance imaging-technique that may mirror tissue cellularity by measuring random movements of water molecules. To investigate if DWI is capable of assessing bone marrow cellularity in monoclonal plasma cell disease, we investigated 56 patients with multiple myeloma or monoclonal gammopathy of undetermined significance, and 30 healthy controls using DWI of the pelvis and/or the lumbar spine. In 25 of 30 patients who underwent biopsy, bone marrow trephine and DWI could be compared. Of the patients with symptomatic disease 15 could be evaluated after systemic treatment. There was a positive correlation between the DWI-parameter apparent diffusion coefficient (ADC) and bone marrow cellularity as well as micro-vessel density (P<0·001 respectively). ADC was significantly different between patients and controls (P<0·01) and before and after systemic therapy (P<0·001). In conclusion, DWI enabled bone marrow infiltration to be monitored in a non-invasive, quantitative way, suggesting that after further investigations on larger patient groups this might become an useful tool in the clinical work-up to assess tumour burden. PMID:21517815

  1. [An acute severe heat stroke patient showing abnormal diffuse high intensity of the cerebellar cortex in diffusion weighted image: a case report].

    PubMed

    Fujioka, Yusuke; Yasui, Keizo; Hasegawa, Yasuhiro; Takahashi, Akira; Sobue, Gen

    2009-10-01

    A 47-year-old man was admitted to the hospital because of general convulsion, loss of consciousness and hyperthermia. A diagnosis of acute heat stroke was made clinically and neuroradiologically. As the consciousness level ameliorated, he developed severe abulia and mutism, then cerebellar ataxic syndrome (viz. truncal ataxia, hypermetria, ataxic speech and nystagmus). An MRI (diffusion weighted image; DWI) disclosed abnormal diffuse high signal intensity of the cerebellar cortex with reduced apparent diffusion coefficient (ADC). Two months later after the onset, truncal ataxia and dysarthria significantly improved, while dysmetria of the extremities rather worsened. At that time, the abnormal signal intensity of the cerebellar cortex disappeared, and the cerebellum became atrophic. The cerebellar blood flow was significantly decreased on brain SPECT (99mTc-ECD). The abnormal DWI signal intensity of the cerebellar cortex in the present patient may represent the cytotoxic edema of Purkinje cells resulting from heat stroke-related hyperthermia It is essential to repeat MRI examination for cerebellar pathology and to obtain better insight into sequelae in patients with acute heat stroke. Protirelin tartrate seemed to be valid for improvement of abulia in the present patient. Further study is indicated. PMID:19999144

  2. New Magnetic Resonance Imaging Index for Renal Fibrosis Assessment: A Comparison between Diffusion-Weighted Imaging and T1 Mapping with Histological Validation.

    PubMed

    Friedli, I; Crowe, L A; Berchtold, L; Moll, S; Hadaya, K; de Perrot, T; Vesin, C; Martin, P-Y; de Seigneux, S; Vallée, J-P

    2016-01-01

    A need exists to noninvasively assess renal interstitial fibrosis, a common process to all kidney diseases and predictive of renal prognosis. In this translational study, Magnetic Resonance Imaging (MRI) T1 mapping and a new segmented Diffusion-Weighted Imaging (DWI) technique, for Apparent Diffusion Coefficient (ADC), were first compared to renal fibrosis in two well-controlled animal models to assess detection limits. Validation against biopsy was then performed in 33 kidney allograft recipients (KARs). Predictive MRI indices, ΔT1 and ΔADC (defined as the cortico-medullary differences), were compared to histology. In rats, both T1 and ADC correlated well with fibrosis and inflammation showing a difference between normal and diseased kidneys. In KARs, MRI indices were not sensitive to interstitial inflammation. By contrast, ΔADC outperformed ΔT1 with a stronger negative correlation to fibrosis (R(2) = 0.64 against R(2) = 0.29 p < 0.001). ΔADC tends to negative values in KARs harboring cortical fibrosis of more than 40%. Using a discriminant analysis method, the ΔADC, as a marker to detect such level of fibrosis or higher, led to a specificity and sensitivity of 100% and 71%, respectively. This new index has potential for noninvasive assessment of fibrosis in the clinical setting. PMID:27439482

  3. A study on quantitative analyses before and after injection of contrast medium in spine examinations performed by using diffusion weighted image

    NASA Astrophysics Data System (ADS)

    Cho, Jae-Hwan; Lee, Hae-Kag; Kim, Yong-Kyun; Dong, Kyung-Rae; Chung, Woon-Kwan; Joo, Kyu-Ji

    2013-02-01

    This study examined the changes in the signal-to-noise ratio (SNR), the contrast-to-noise ratio (CNR) and the apparent diffusion coefficient (ADC) of metastatic cancer in the lumbar region by using diffusion weighted image taken with a 1.5 T (Tesla) magnetic resonance (MR) scanner before and after injecting a contrast medium. The study enrolled 30 healthy people and 30 patients with metastatic spine cancer from patients who underwent a lumbar MRI scan from January 2011 to October 2012. A 1.5 T MR scanner was used to obtain the diffusion weighted images (DWIs) before and after injecting the contrast medium. In the group with metastatic spine cancer, the SNR and the CNR were measured in three parts among the L1-L5 lumbar vertebrae, which included the part with metastatic spine cancer, the area of the spine with spine cancer, and the area of spine under the region with cancer. In the acquired ADC map image, the SNRs and the ADCs of the three parts were measured in ADC map images. Among the healthy subjects, the measurements were conducted for the lumbar regions of L3-L5. According to the results, in the group with metastatic spine cancer, the SNR in the DWI before the contrast medium had been injected was lowest in the part with spine cancer. In the DWI after the contrast medium had been injected, the SNR and the CNR were increased in all three parts. In the ADC map image after the contrast medium had been injected, the SNR decreased in all three parts compared to the SNR before the contrast had been injected. The ADC after had been injected the contrast medium was decreased in all three parts compared to that before the contrast medium had been injected. In the healthy group, the SNR was increased in the L3-L5 lumbar regions in the DWI. In the ADC map image, the SNR in all the three parts was decreased in the DWI after injecting the contrast medium had been injected. The ADC in the ADC map image was also decreased in all three parts.

  4. Monitoring of the tumor response to nano-graphene oxide-mediated photothermal/photodynamic therapy by diffusion-weighted and BOLD MRI

    NASA Astrophysics Data System (ADS)

    Cao, Jianbo; An, Hengqing; Huang, Xinglu; Fu, Guifeng; Zhuang, Rongqiang; Zhu, Lei; Xie, Jin; Zhang, Fan

    2016-05-01

    Photothermal therapy (PTT) and photodynamic therapy (PDT) are promising cancer treatment modalities. Because each modality has its own set of advantages and limitations, there has been interest in developing methods that can co-deliver the two regimens for enhanced tumor treatment. Among the efforts, nano-graphene oxide-mediated phototherapies have recently attracted much attention. Nano-graphene oxide has a broad absorbance spectrum and can be loaded with photosensitizers, such as chlorin e6, with high efficiency. Chlorin e6-loaded and PEGylated nano-graphene (GO-PEG-Ce6) can be excited at 660 nm, 808 nm, or both, to induce PDT, PTT, or PDT/PTT combination. Despite the potential of the treatments, there is a lack of a diagnostic tool which can monitor their therapeutic response in a non-invasive and prognostic manner; such an ability is urgently needed for the transformation and translation of the technologies. In this study, we performed diffusion-weighted and blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) after GO-PEG-Ce6-mediated PTT, PDT, or PTT/PDT. We found that after efficient PTT, there is a significant increase of the tumor apparent diffusion coefficient (ADC) value in diffusion-weighted imaging (DWI) maps; meanwhile, an efficient PDT led to an increase of in BOLD images. In both the cases, the amplitude of the increase was correlated with the treatment outcomes. More interestingly, a synergistic treatment efficacy was observed when the PTT/PDT combination was applied, and the combination was associated with a greater ADC and increase than when either modality was used alone. In particular, the PTT/PDT condition that induced the most dramatic short-term increase of the ADC value (>70%) caused the most effective tumor control in the long-run, with 60% of the treated animals being tumor-free after 60 days. These results suggest the great promise of the combination of DWI and BOLD MRI as a tool for accurate monitoring and prognosis

  5. Monitoring of the tumor response to nano-graphene oxide-mediated photothermal/photodynamic therapy by diffusion-weighted and BOLD MRI.

    PubMed

    Cao, Jianbo; An, Hengqing; Huang, Xinglu; Fu, Guifeng; Zhuang, Rongqiang; Zhu, Lei; Xie, Jin; Zhang, Fan

    2016-05-21

    Photothermal therapy (PTT) and photodynamic therapy (PDT) are promising cancer treatment modalities. Because each modality has its own set of advantages and limitations, there has been interest in developing methods that can co-deliver the two regimens for enhanced tumor treatment. Among the efforts, nano-graphene oxide-mediated phototherapies have recently attracted much attention. Nano-graphene oxide has a broad absorbance spectrum and can be loaded with photosensitizers, such as chlorin e6, with high efficiency. Chlorin e6-loaded and PEGylated nano-graphene (GO-PEG-Ce6) can be excited at 660 nm, 808 nm, or both, to induce PDT, PTT, or PDT/PTT combination. Despite the potential of the treatments, there is a lack of a diagnostic tool which can monitor their therapeutic response in a non-invasive and prognostic manner; such an ability is urgently needed for the transformation and translation of the technologies. In this study, we performed diffusion-weighted and blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) after GO-PEG-Ce6-mediated PTT, PDT, or PTT/PDT. We found that after efficient PTT, there is a significant increase of the tumor apparent diffusion coefficient (ADC) value in diffusion-weighted imaging (DWI) maps; meanwhile, an efficient PDT led to an increase of in BOLD images. In both the cases, the amplitude of the increase was correlated with the treatment outcomes. More interestingly, a synergistic treatment efficacy was observed when the PTT/PDT combination was applied, and the combination was associated with a greater ADC and increase than when either modality was used alone. In particular, the PTT/PDT condition that induced the most dramatic short-term increase of the ADC value (>70%) caused the most effective tumor control in the long-run, with 60% of the treated animals being tumor-free after 60 days. These results suggest the great promise of the combination of DWI and BOLD MRI as a tool for accurate monitoring and prognosis

  6. Value of apparent diffusion coefficient for predicting malignancy of intraductal papillary mucinous neoplasms of the pancreas

    PubMed Central

    Zhang, Lei; Rao, Sheng-Xiang; Xu, Xue-Feng; Wang, Dan-Song; Jin, Da-Yong; Zeng, Meng-Su

    2016-01-01

    PURPOSE We aimed to explore the potential value of the whole tumor apparent diffusion coefficient (ADC) for discriminating between benign and malignant intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. METHODS Forty-two patients underwent 1.5 T magnetic resonance imaging that included diffusion-weighted imaging (DWI, b=0.500 s/mm2). The mean, minimum, and maximum ADC values were measured for the whole tumor. The differences between benign and malignant IPMNs were calculated for the mean ADC, ADC-min, and ADC-max values. Receiver operating characteristics (ROC) analysis was conducted to evaluate their potential diagnostic performance. RESULTS Fifteen of 25 benign IPMNs demonstrated low or iso-signal intensity on DWI with a b value of 500 s/mm2 compared with normal pancreatic parenchyma, whereas all malignant IPMNs demonstrated high signal intensity. The mean value of ADC was significantly higher in benign IPMNs compared with malignant IPMNs (3.39×10−3 mm2/s vs. 2.39×10−3 mm2/s, P < 0.001), with an area under the ROC curve (AUC) of 0.92 (95% confidence interval [CI], 0.79–0.98). The ADC-min value of malignant IPMNs was also significantly lower than that of benign IPMNs (1.24×10−3 mm2/s vs. 2.58×10−3 mm2/s, P < 0.001), with an AUC of 0.94 (95% CI, 0.82–0.99). No marked difference was found between benign and malignant IPMNs for the ADC-max value (3.89×10−3 mm2/s vs. 3.78×10−3 mm2/s, P = 0.299). CONCLUSION Lower mean and minimum ADC values of the whole tumor might be potential predictors of malignant IPMNs of the pancreas. PMID:27283593

  7. Progression of striatal and extrastriatal degeneration in multiple system atrophy: a longitudinal diffusion-weighted MR study.

    PubMed

    Pellecchia, Maria Teresa; Barone, Paolo; Vicidomini, Caterina; Mollica, Carmine; Salvatore, Elena; Ianniciello, Marta; Liuzzi, Raffaele; Longo, Katia; Picillo, Marina; De Michele, Giuseppe; Filla, Alessandro; Brunetti, Arturo; Salvatore, Marco; Pappatà, Sabina

    2011-06-01

    Diffusion-weighted imaging has been largely used to detect and quantify early degenerative changes in patients with multiple system atrophy, but progression of neurodegeneration has been poorly investigated. We performed a serial diffusion-weighted imaging study in a population of multiple system atrophy patients and analyzed the evolution of diffusion properties in striatal and extrastriatal brain regions. Diffusion-weighted imaging was obtained in 11 multiple system atrophy patients at baseline and after a follow-up of 11.7 ± 1.2 months, and Trace (D) changes in different brain regions were correlated with disease duration and severity. A significant increase in Trace (D) was observed at follow-up in the putamen (P < .001), pons (P = .003), cerebellar white matter (P = .03), thalamus (P = .013), and frontal white matter (P = .021). Both Unified Multiple System Atrophy Rating Scale Part II and Unified Parkinson's Disease Rating Scale Part III scores significantly increased at follow-up (P = .003), but percent changes of Unified Parkinson's Disease Rating Scale Part III and Unified Multiple System Atrophy Rating Scale Part II did not correlate with percent changes of Trace (D) values in any brain region. This longitudinal study provides new insights into the progression of neurodegeneration in different brain regions in multiple system atrophy. Our results confirm that abnormal diffusivity in the putamen is sensitive to change over time in multiple system atrophy patients and show for the first time a progression of Trace (D) alterations in specific extrastriatal regions. Diffusivity changes in these regions may be useful for monitoring disease progression even after a short follow-up period. © 2011 Movement Disorder Society. PMID:21469200

  8. The value of intravoxel incoherent motion model-based diffusion-weighted imaging for outcome prediction in resin-based radioembolization of breast cancer liver metastases

    PubMed Central

    Pieper, Claus Christian; Meyer, Carsten; Sprinkart, Alois Martin; Block, Wolfgang; Ahmadzadehfar, Hojjat; Schild, Hans Heinz; Mürtz, Petra; Kukuk, Guido Matthias

    2016-01-01

    Purpose To evaluate prognostic values of clinical and diffusion-weighted magnetic resonance imaging-derived intravoxel incoherent motion (IVIM) parameters in patients undergoing primary radioembolization for metastatic breast cancer liver metastases. Subjects and methods A total of 21 females (mean age 54 years, range 43–72 years) with liver-dominant metastatic breast cancer underwent standard liver magnetic resonance imaging (1.5 T, diffusion-weighted imaging with b-values of 0, 50, and 800 s/mm2) before and 4–6 weeks after radioembolization. The IVIM model-derived estimated diffusion coefficient D’ and the perfusion fraction f’ were evaluated by averaging the values of the two largest treated metastases in each patient. Kaplan–Meier and Cox regression analyses for overall survival (OS) were performed. Investigated parameters were changes in f’- and D’-values after therapy, age, sex, Eastern Cooperative Oncology Group (ECOG) status, grading of primary tumor, hepatic tumor burden, presence of extrahepatic disease, baseline bilirubin, previous bevacizumab therapy, early stasis during radioembolization, chemotherapy after radioembolization, repeated radioembolization and Response Evaluation Criteria in Solid Tumors (RECIST) response at 6-week follow-up. Results Median OS after radioembolization was 6 (range 1.5–54.9) months. In patients with therapy-induced decreasing or stable f’-values, median OS was significantly longer than in those with increased f’-values (7.6 [range 2.6–54.9] vs 2.6 [range 1.5–17.4] months, P<0.0001). Longer median OS was also seen in patients with increased D’-values (6 [range 1.6–54.9] vs 2.8 [range 1.5–17.4] months, P=0.008). Patients with remission or stable disease (responders) according to RECIST survived longer than nonresponders (7.2 [range 2.6–54.9] vs 2.6 [range 1.5–17.4] months, P<0.0001). An ECOG status ≤1 resulted in longer median OS than >1 (7.6 [range 2.6–54.9] vs 1.7 [range 1.5–4

  9. Simulations on the influence of myelin water in diffusion-weighted imaging

    NASA Astrophysics Data System (ADS)

    Harkins, K. D.; Does, M. D.

    2016-07-01

    While myelinated axons present an important barrier to water diffusion, many models used to interpret DWI signal neglect other potential influences of myelin. In this work, Monte Carlo simulations were used to test the sensitivity of DWI results to the diffusive properties of water within myelin. Within these simulations, the apparent diffusion coefficient (D app) varied slowly over several orders of magnitude of the coefficient of myelin water diffusion (D m), but exhibited important differences compared to D app values simulated that neglect D m (=0). Compared to D app, the apparent diffusion kurtosis (K app) was generally more sensitive to D m. Simulations also tested the sensitivity of D app and K app to the amount of myelin present. Unique variations in D app and K app caused by differences in the myelin volume fraction were diminished when myelin water diffusion was included. Also, expected trends in D app and K app with experimental echo time were reduced or inverted when accounting for myelin water diffusion, and these reduced/inverted trends were seen experimentally in ex vivo rat brain DWI experiments. In general, myelin water has the potential to subtly influence DWI results and bias models of DWI that neglect these components of white matter.

  10. Simulations on the influence of myelin water in diffusion-weighted imaging.

    PubMed

    Harkins, K D; Does, M D

    2016-07-01

    While myelinated axons present an important barrier to water diffusion, many models used to interpret DWI signal neglect other potential influences of myelin. In this work, Monte Carlo simulations were used to test the sensitivity of DWI results to the diffusive properties of water within myelin. Within these simulations, the apparent diffusion coefficient (D app) varied slowly over several orders of magnitude of the coefficient of myelin water diffusion (D m), but exhibited important differences compared to D app values simulated that neglect D m (=0). Compared to D app, the apparent diffusion kurtosis (K app) was generally more sensitive to D m. Simulations also tested the sensitivity of D app and K app to the amount of myelin present. Unique variations in D app and K app caused by differences in the myelin volume fraction were diminished when myelin water diffusion was included. Also, expected trends in D app and K app with experimental echo time were reduced or inverted when accounting for myelin water diffusion, and these reduced/inverted trends were seen experimentally in ex vivo rat brain DWI experiments. In general, myelin water has the potential to subtly influence DWI results and bias models of DWI that neglect these components of white matter. PMID:27271991

  11. Predictive classification of pediatric bipolar disorder using atlas-based diffusion weighted imaging and support vector machines.

    PubMed

    Mwangi, Benson; Wu, Mon-Ju; Bauer, Isabelle E; Modi, Haina; Zeni, Cristian P; Zunta-Soares, Giovana B; Hasan, Khader M; Soares, Jair C

    2015-11-30

    Previous studies have reported abnormalities of white-matter diffusivity in pediatric bipolar disorder. However, it has not been established whether these abnormalities are able to distinguish individual subjects with pediatric bipolar disorder from healthy controls with a high specificity and sensitivity. Diffusion-weighted imaging scans were acquired from 16 youths diagnosed with DSM-IV bipolar disorder and 16 demographically matched healthy controls. Regional white matter tissue microstructural measurements such as fractional anisotropy, axial diffusivity and radial diffusivity were computed using an atlas-based approach. These measurements were used to 'train' a support vector machine (SVM) algorithm to predict new or 'unseen' subjects' diagnostic labels. The SVM algorithm predicted individual subjects with specificity=87.5%, sensitivity=68.75%, accuracy=78.12%, positive predictive value=84.62%, negative predictive value=73.68%, area under receiver operating characteristic curve (AUROC)=0.7812 and chi-square p-value=0.0012. A pattern of reduced regional white matter fractional anisotropy was observed in pediatric bipolar disorder patients. These results suggest that atlas-based diffusion weighted imaging measurements can distinguish individual pediatric bipolar disorder patients from healthy controls. Notably, from a clinical perspective these findings will contribute to the pathophysiological understanding of pediatric bipolar disorder. PMID:26459075

  12. Multi-modal pharmacokinetic modelling for DCE-MRI: using diffusion weighted imaging to constrain the local arterial input function

    NASA Astrophysics Data System (ADS)

    Hamy, Valentin; Modat, Marc; Shipley, Rebecca; Dikaios, Nikos; Cleary, Jon; Punwani, Shonit; Ourselin, Sebastien; Atkinson, David; Melbourne, Andrew

    2014-03-01

    The routine acquisition of multi-modal magnetic resonance imaging data in oncology yields the possibility of combined model fitting of traditionally separate models of tissue structure and function. In this work we hypothesise that diffusion weighted imaging data may help constrain the fitting of pharmacokinetic models to dynamic contrast enhanced (DCE) MRI data. Parameters related to tissue perfusion in the intra-voxel incoherent motion (IVIM) modelling of diffusion weighted MRI provide local information on how tissue is likely to perfuse that can be utilised to guide DCE modelling via local modification of the arterial input function (AIF). In this study we investigate, based on multi-parametric head and neck MRI of 8 subjects (4 with head and neck tumours), the benefit of incorporating parameters derived from the IVIM model within the DCE modelling procedure. Although we find the benefit of this procedure to be marginal on the data used in this work, it is conceivable that a technique of this type will be of greater use in a different application.

  13. Apparent diffusion coefficient map of a case of extramedullary plasmacytoma

    PubMed Central

    Ramachandran, Amrutha; Inyang, Alero F; Subhawong, Ty K

    2016-01-01

    Plasmacytomas are rare tumors, which arise from the monoclonal proliferation of malignant plasma cells. They may affect either the bony skeleton or rarely the soft tissues, the latter being referred to as extramedullary or extraosseous. We report a case of an extramedullary plasmacytoma that presented as a soft tissue mass involving the muscles of the left leg, in a patient who was previously treated for multiple myeloma. We describe the MR Imaging characteristics of the tumor and highlight the usefulness of diffusion-weighted imaging with apparent diffusion coefficient mapping. PMID:27200157

  14. Prediction of Early Response to Chemotherapy in Lung Cancer by Using Diffusion-Weighted MR Imaging

    PubMed Central

    Yu, Jing; Li, Weidong; Zhang, Zhang; Yu, Tielian; Li, Dong

    2014-01-01

    Purpose. To determine whether change of apparent diffusion coefficient (ADC) value could predict early response to chemotherapy in lung cancer. Materials and Methods. Twenty-five patients with advanced non-small cell lung cancer underwent chest MR imaging including DWI before and at the end of the first cycle of chemotherapy. The tumor's mean ADC value and diameters on MR images were calculated and compared. The grouping reference was based on serial CT scans according to Response Evaluation Criteria in Solid Tumors. Logistic regression was applied to assess treatment response prediction ability of ADC value and diameters. Results. The change of ADC value in partial response group was higher than that in stable disease group (P = 0.004). ROC curve showed that ADC value could predict treatment response with 100% sensitivity, 64.71% specificity, 57.14% positive predictive value, 100% negative predictive value, and 82.7% accuracy. The area under the curve for combination of ADC value and longest diameter change was higher than any parameter alone (P ≤ 0.01). Conclusions. The change of ADC value may be a sensitive indicator to predict early response to chemotherapy in lung cancer. Prediction ability could be improved by combining the change of ADC value and longest diameter. PMID:24688359

  15. Diagnostic Performance of Fused Diffusion-Weighted Imaging Using Unenhanced or Postcontrast T1-Weighted MR Imaging in Patients With Breast Cancer

    PubMed Central

    Shin, Hee Jung; Chae, Eun Young; Choi, Woo Jung; Ha, Su Min; Park, Jin Young; Shin, Ki Chang; Cha, Joo Hee; Kim, Hak Hee

    2016-01-01

    Abstract To evaluate the diagnostic performance of fused diffusion-weighted imaging (DWI) using either unenhanced (UFMR) or early postcontrast T1-weighted imaging (PCFMR) to detect and characterize breast lesions in patients with breast cancer. This retrospective observational study was approved by institutional review board in our hospital and informed consents were waived. We retrospectively selected 87 consecutive patients who underwent preoperative breast magnetic resonance imaging, including DWI and definitive surgery. Both UFMR and PCFMR were reviewed by 5 radiologists for detection, lesion size, Breast Imaging Reporting and Data System final assessment, the probability of malignancy, lesion conspicuity, and apparent diffusion coefficients. A total of 129 lesions were identified by at least 2 readers on UFMR or PCFMR. Of 645 potentially detected lesions, there were 528 (82%) with UFMR and 554 (86%) with PCFMR. Malignant lesions or index cancers showed significantly higher detection rates than benign or additional lesions on both UFMR and PCFMR (P < 0.05). Area under the characteristic curves (AUCs) for predicting malignancy ranged 0.927 to 0.986 for UFMR, and 0.936 to 0.993 for PCFMR, which was not significantly different. Lesion conspicuity was significantly higher on PCFMR than UFMR (8.59 ± 1.67 vs 9.19 ± 1.36, respectively; P < 0.05) across 5 readers. Mean intraclass correlation coefficients for lesion size on UFMR and PCFMR were 0.89 and 0.92, respectively. Detection rates of index malignant lesions were similar for UFMR and PCFMR. Interobserver agreement for final assessments was reliable across 5 readers. Diagnostic accuracy for predicting malignancy with UFMR versus PCFMR was similar, although lesion conspicuity was significantly greater with the latter. PMID:27124054

  16. Using Diffusion-Weighted MRI to Predict Aggressive Histological Features in Papillary Thyroid Carcinoma: A Novel Tool for Pre-Operative Risk Stratification in Thyroid Cancer

    PubMed Central

    Lu, Yonggang; Moreira, Andre L.; Hatzoglou, Vaios; Stambuk, Hilda E.; Gonen, Mithat; Mazaheri, Yousef; Deasy, Joseph O.; Shaha, Ashok R.

    2015-01-01

    Background: Initial management recommendations of papillary thyroid carcinoma (PTC) are very dependent on preoperative studies designed to evaluate the presence of PTC with aggressive features. The purpose of this study was to evaluate whether diffusion-weighted magnetic resonance imaging (DW-MRI) before surgery can be used as a tool to stratify tumor aggressiveness in patients with PTC. Methods: In this prospective study, 28 patients with PTC underwent DW-MRI studies on a three Tesla MR scanner prior to thyroidectomy. Due to image quality, 21 patients were finally suitable for further analysis. Apparent diffusion coefficients (ADCs) of normal thyroid tissues and PTCs for 21 patients were calculated. Tumor aggressiveness was defined by surgical histopathology. The Mann-Whitney U test was used to compare the difference in ADCs among groups of normal thyroid tissues and PTCs with and without features of tumor aggressiveness. Receiver operating characteristic (ROC) analysis was performed to assess the discriminative specificity, sensitivity, and accuracy of and determine the cutoff value for the ADC in stratifying PTCs with tumor aggressiveness. Results: There was no significant difference in ADC values between normal thyroid tissues and PTCs. However, ADC values of PTCs with extrathyroidal extension (ETE; 1.53±0.25×10–3 mm2/s) were significantly lower than corresponding values from PTCs without ETE (2.37±0.67×10–3 mm2/s; p<0.005). ADC values identified 3 papillary carcinoma patients with extrathyroidal extension that would have otherwise been candidates for observation based on ultrasound evaluations. The cutoff value of ADC to discriminate PTCs with and without ETE was determined at 1.85×10–3 mm2/s with a sensitivity of 85%, specificity of 85%, and ROC curve area of 0.85. Conclusion: ADC value derived from DW-MRI before surgery has the potential to stratify ETE in patients with PTCs. PMID:25809949

  17. Cerebral edema induced in mice by a convulsive dose of soman. Evaluation through diffusion-weighted magnetic resonance imaging and histology

    SciTech Connect

    Testylier, Guy . E-mail: guytestylier@crssa.net; Lahrech, Hana; Montigon, Olivier; Foquin, Annie; Delacour, Claire; Bernabe, Denis; Segebarth, Christoph; Dorandeu, Frederic; Carpentier, Pierre

    2007-04-15

    Purpose: In the present study, diffusion-weighted magnetic resonance imaging (DW-MRI) and histology were used to assess cerebral edema and lesions in mice intoxicated by a convulsive dose of soman, an organophosphate compound acting as an irreversible cholinesterase inhibitor. Methods: Three hours and 24 h after the intoxication with soman (172 {mu}g/kg), the mice were anesthetized with an isoflurane/N{sub 2}O mixture and their brain examined with DW-MRI. After the imaging sessions, the mice were sacrificed for histological analysis of their brain. Results: A decrease in the apparent diffusion coefficient (ADC) was detected as soon as 3 h after the intoxication and was found strongly enhanced at 24 h. A correlation was obtained between the ADC change and the severity of the overall brain damage (edema and cellular degeneration): the more severe the damage, the stronger the ADC drop. Anesthesia was shown to interrupt soman-induced seizures and to attenuate edema and cell change in certain sensitive brain areas. Finally, brain water content was assessed using the traditional dry/wet weight method. A significant increase of brain water was observed following the intoxication. Conclusions: The ADC decrease observed in the present study suggests that brain edema in soman poisoning is mainly intracellular and cytotoxic. Since entry of water into Brain was also evidenced, this type of edema is certainly mixed with others (vasogenic, hydrostatic, osmotic). The present study confirms the potential of DW-MRI as a non-invasive tool for monitoring the acute neuropathological consequences (edema and neurodegeneration) of soman-induced seizures.

  18. The Role of Diffusion-Weighted Magnetic Resonance Imaging in the Treatment Response Evaluation of Hepatocellular Carcinoma Patients Treated With Radiation Therapy

    SciTech Connect

    Yu, Jeong Il; Park, Hee Chul; Lim, Do Hoon; Choi, Yunseon; Jung, Sang Hoon; Paik, Seung Woon; Kim, Seong Hyun; Jeong, Woo Kyoung; Kim, Young Kon

    2014-07-15

    Purpose: We investigated the role of diffusion-weighted magnetic resonance imaging (DW MRI) as a response evaluation indicator for hepatocellular carcinoma (HCC) treated with radiation therapy (RT). Methods and Materials: Inclusion criteria of this retrospective study were DW MRI acquisition within 1 month before and 3 to 5 months after RT. In total, 48 patients were enrolled. Two radiation oncologists measured the apparent diffusion coefficient (ADC). Possible predictive factors, including alteration of the ADC value before and 3 to 5 month after RT, in relation to local progression-free survival (LPFS) were analyzed and compared. Results: Three months after RT, 6 patients (12.5%) showed a complete response, and 27 patients (56.3%) showed a partial response when evaluated using the modified response evaluation criteria in solid tumors (mRECIST). The average ADC ± SD values were 1.21 ± 0.27 ( × 10{sup −3} mm{sup 2}/s) before and 1.41 ± 0.36 ( × 10{sup −3} mm{sup 2}/s) after RT (P<.001). The most significant prognostic factor related to LPFS was mRECIST (P<.001). The increment of ADC value (≥20%) was also a significant factor (P=.02), but RECIST (version 1.1; P=.11) was not. When RECIST was combined with the increment of ADC value (≥20%), the LPFS rates were significantly different between the groups (P=.004), and the area under the curve value (0.745) was comparable with that of mRECIST (0.765). Conclusions: ADC value change before and after RT in HCC was closely related to LPFS. ADC value and RECIST may substitute for mRECIST in patients who cannot receive contrast agents.

  19. Differentiating Laryngeal Carcinomas from Precursor Lesions by Diffusion-Weighted Magnetic Resonance Imaging at 3.0 T: A Preliminary Study

    PubMed Central

    Shang, De-Sheng; Ruan, Ling-Xiang; Zhou, Shui-Hong; Bao, Yang-Yang; Cheng, Ke-Jia; Wang, Qin-Ying

    2013-01-01

    Background Diffusion-weighted magnetic resonance imaging (DWI) has been introduced in head and neck cancers. Due to limitations in the performance of laryngeal DWI, including the complex anatomical structure of the larynx leading to susceptibility effects, the value of DWI in differentiating benign from malignant laryngeal lesions has largely been ignored. We assessed whether a threshold for the apparent diffusion coefficient (ADC) was useful in differentiating preoperative laryngeal carcinomas from precursor lesions by turbo spin-echo (TSE) DWI and 3.0-T magnetic resonance. Methods We evaluated DWI and the ADC value in 33 pathologically proven laryngeal carcinomas and 17 precancerous lesions. Results The sensitivity, specificity, and accuracy were 81.8%, 64.7%, 76.0% by laryngostroboscopy, respectively. The sensitivity, specificity, and accuracy of conventional magnetic resonance imaging were 90.9%, 76.5%, 86.0%, respectively. Qualitative DWI analysis produced sensitivity, specificity, and accuracy values of 100.0, 88.2, and 96.0%, respectively. The ADC values were lower for patients with laryngeal carcinoma (mean 1.195±0.32×10−3 mm2/s) versus those with laryngeal precancerous lesions (mean 1.780±0.32×10−3 mm2/s; P<0.001). ROC analysis showed that the area under the curve was 0.956 and the optimum threshold for the ADC was 1.455×10−3 mm2/s, resulting in a sensitivity of 94.1%, a specificity of 90.9%, and an accuracy of 92.9%. Conclusions Despite some limitations, including the small number of laryngeal carcinomas included, DWI may detect changes in tumor size and shape before they are visible by laryngostroboscopy. The ADC values were lower for patients with laryngeal carcinoma than for those with laryngeal precancerous lesions. The proposed cutoff for the ADC may help distinguish laryngeal carcinomas from laryngeal precancerous lesions. PMID:23874693

  20. Pitfalls in whole body MRI with diffusion weighted imaging performed on patients with lymphoma: What radiologists should know.

    PubMed

    Albano, Domenico; La Grutta, Ludovico; Grassedonio, Emanuele; Patti, Caterina; Lagalla, Roberto; Midiri, Massimo; Galia, Massimo

    2016-09-01

    The technological advances in radiological imaging and the relevance of a diagnostic tool that may reduce radiation-induced long-term effects have led to a widespread use of whole body magnetic resonance imaging (WB-MRI) with diffusion weighted imaging for oncologic patients. A lot of studies demonstrated the feasibility and reliability of WB-MRI as an alternative technique for lymphoma staging and response assessment during and after treatment. In this paper, taking advantage of our 2years of experience using WB-MRI for lymphoma, we discuss the main pitfalls and artifacts radiologists should know examining a WB-MRI performed on this typology of patients in order to avoid images misinterpretation. PMID:27114337

  1. Scan parameters and the diffusion emphasis effect in diffusion-weighted imaging using a motion-probing gradient preparation pulse.

    PubMed

    Takahashi, Daisuke; Tanji, Hajime; Yamaki, Tomoya; Obara, Makoto; Machida, Yoshio

    2014-07-01

    Diffusion-sensitized driven equilibrium preparation (DSDE) is a gradient echo (GRE) diffusion-weighted imaging (DWI) sequence that employs a motion-probing gradient (MPG) preparation pulse and phase cycling. In DSDE, several scan parameters of the MPG preparation pulse and the GRE sequence affect diffusion sensitivity. Our investigation of the relationship between these scan parameters and the diffusion emphasis effect revealed the importance of "prep.TE" in the MPG preparation pulse and "TFE shot interval" in the gradient echo sequence. Appropriate choice of these parameters allows DSDE to provide a similar DWI to that of conventional single-shot SEEPI DWI. We therefore concluded DSDE to be a useful DWI method. PMID:25055943

  2. lop-DWI: A Novel Scheme for Pre-Processing of Diffusion-Weighted Images in the Gradient Direction Domain

    PubMed Central

    Sepehrband, Farshid; Choupan, Jeiran; Caruyer, Emmanuel; Kurniawan, Nyoman D.; Gal, Yaniv; Tieng, Quang M.; McMahon, Katie L.; Vegh, Viktor; Reutens, David C.; Yang, Zhengyi

    2015-01-01

    We describe and evaluate a pre-processing method based on a periodic spiral sampling of diffusion-gradient directions for high angular resolution diffusion magnetic resonance imaging. Our pre-processing method incorporates prior knowledge about the acquired diffusion-weighted signal, facilitating noise reduction. Periodic spiral sampling of gradient direction encodings results in an acquired signal in each voxel that is pseudo-periodic with characteristics that allow separation of low-frequency signal from high frequency noise. Consequently, it enhances local reconstruction of the orientation distribution function used to define fiber tracks in the brain. Denoising with periodic spiral sampling was tested using synthetic data and in vivo human brain images. The level of improvement in signal-to-noise ratio and in the accuracy of local reconstruction of fiber tracks was significantly improved using our method. PMID:25628600

  3. Preoperative CT versus diffusion weighted magnetic resonance imaging of the liver in patients with rectal cancer; a prospective randomized trial

    PubMed Central

    Løgager, Vibeke B.; Skjoldbye, Bjørn; Møller, Jakob M.; Lorenzen, Torben; Rasmussen, Vera L.; Thomsen, Henrik S.; Mollerup, Talie H.; Okholm, Cecilie; Rosenberg, Jacob

    2016-01-01

    Introduction. Colorectal cancer is one of the most frequent cancers in the world and liver metastases are seen in up to 19% of patients with colorectal cancers. Detection of liver metastases is not only vital for sufficient treatment and survival, but also for a better estimation of prognosis. The aim of this study was to evaluate the feasibility of diffusion weighted MRI of the liver as part of a combined MR evaluation of patients with rectal cancers and compare it with the standard preoperative evaluation of the liver with CT. Methods. Consecutive patients diagnosed with rectal cancers were asked to participate in the study. Preoperative CT and diffusion weighted MR (DWMR) were compared to contrast enhanced laparoscopic ultrasound (CELUS). Results. A total of 35 patients were included, 15 patients in Group-1 having the standard CT evaluation of the liver and 20 patients in Group-2 having the standard CT evaluation of the liver and DWMR of the liver. Compared with CELUS, the per-patient sensitivity/specificity was 50/100% for CT, and for DWMR: 100/94% and 100/100% for Reader 1 and 2, respectively. The per-lesion sensitivity of CT and DWMR were 17% and 89%, respectively compared with CELUS. Furthermore, one patient had non-resectable metastases after DWMR despite being diagnosed with resectable metastases after CT. Another patient was diagnosed with multiple liver metastases during CELUS, despite a negative CT-scan. Discussion. DWMR is feasible for preoperative evaluation of liver metastases. The current standard preoperative evaluation with CT-scan results in disadvantages like missed metastases and futile operations. We recommend that patients with rectal cancer, who are scheduled for MR of the rectum, should have a DWMR of the liver performed at the same time. PMID:26793420

  4. Strain rate dependency of oceanic intraplate earthquake b-values at extremely low strain rates

    NASA Astrophysics Data System (ADS)

    Sasajima, Ryohei; Ito, Takeo

    2016-06-01

    We discovered a clear positive dependence of oceanic intraplate earthquake (OCEQ) b-values on the age of the oceanic lithosphere. OCEQ b-values in the youngest (<10 Ma) oceanic lithosphere are around 1.0, while those in middle to old (>20 Ma) oceanic lithosphere exceed 1.5, which is significantly higher than the average worldwide earthquake b-value (around 1.0). On the other hand, the b-value of intraplate earthquakes in the Ninety East-Sumatra orogen, where oceanic lithosphere has an anomalously higher strain rate compared with normal oceanic lithosphere, is 0.93, which is significantly lower than the OCEQ b-value (about 1.9) with the same age (50-110 Ma). Thus, the variation in b-values relates to the strain rate of the oceanic lithosphere and is not caused by a difference in thermal structure. We revealed a negative strain rate dependency of the b-value at extremely low strain rates (<2 × 10-10/year), which can clearly explain the above b-values. We propose that the OCEQ b-value depends strongly on strain rate (either directly or indirectly) at extremely low strain rates. The high OCEQ b-values (>1.5) in oceanic lithosphere >20 Ma old imply that future improvement in seismic observation will capture many smaller magnitude OCEQs, which will provide valuable information on the evolution of the oceanic lithosphere and the driving mechanism of plate tectonics.

  5. In vivo High Angular Resolution Diffusion-Weighted Imaging of Mouse Brain at 16.4 Tesla

    PubMed Central

    Alomair, Othman I.; Brereton, Ian M.; Smith, Maree T.; Galloway, Graham J.; Kurniawan, Nyoman D.

    2015-01-01

    Magnetic Resonance Imaging (MRI) of the rodent brain at ultra-high magnetic fields (> 9.4 Tesla) offers a higher signal-to-noise ratio that can be exploited to reduce image acquisition time or provide higher spatial resolution. However, significant challenges are presented due to a combination of longer T1 and shorter T2/T2* relaxation times and increased sensitivity to magnetic susceptibility resulting in severe local-field inhomogeneity artefacts from air pockets and bone/brain interfaces. The Stejskal-Tanner spin echo diffusion-weighted imaging (DWI) sequence is often used in high-field rodent brain MRI due to its immunity to these artefacts. To accurately determine diffusion-tensor or fibre-orientation distribution, high angular resolution diffusion imaging (HARDI) with strong diffusion weighting (b >3000 s/mm2) and at least 30 diffusion-encoding directions are required. However, this results in long image acquisition times unsuitable for live animal imaging. In this study, we describe the optimization of HARDI acquisition parameters at 16.4T using a Stejskal-Tanner sequence with echo-planar imaging (EPI) readout. EPI segmentation and partial Fourier encoding acceleration were applied to reduce the echo time (TE), thereby minimizing signal decay and distortion artefacts while maintaining a reasonably short acquisition time. The final HARDI acquisition protocol was achieved with the following parameters: 4 shot EPI, b = 3000 s/mm2, 64 diffusion-encoding directions, 125×150 μm2 in-plane resolution, 0.6 mm slice thickness, and 2h acquisition time. This protocol was used to image a cohort of adult C57BL/6 male mice, whereby the quality of the acquired data was assessed and diffusion tensor imaging (DTI) derived parameters were measured. High-quality images with high spatial and angular resolution, low distortion and low variability in DTI-derived parameters were obtained, indicating that EPI-DWI is feasible at 16.4T to study animal models of white matter (WM

  6. Apparent-Dip Methods.

    ERIC Educational Resources Information Center

    Travis, R. B.; Lamar, D. L.

    1987-01-01

    Reviews methods of determining apparent dip and highlights the use of a device which consists of a nomogram printed on a protractor. Explains how the apparent-dip calculator-protractor can be constructed and outlines the steps for its operation. (ML)

  7. Intraventricular temperature measured by diffusion-weighted imaging compared with brain parenchymal temperature measured by MRS in vivo.

    PubMed

    Sumida, Kaoru; Sato, Noriko; Ota, Miho; Sakai, Koji; Sone, Daichi; Yokoyama, Kota; Kimura, Yukio; Maikusa, Norihide; Imabayashi, Etsuko; Matsuda, Hiroshi; Kunimatsu, Akira; Ohtomo, Kuni

    2016-07-01

    We examined and compared the temperatures of the intraventricular cerebrospinal fluid (Tv ) and the brain parenchyma (Tp ) using MRI, with reference to the tympanic membrane temperature (Tt ) in healthy subjects. We estimated Tv and Tp values from data gathered simultaneously by MR diffusion-weighted imaging (DWI) and MRS, respectively, in 35 healthy volunteers (17 males, 18 females; age 25-78 years). We also obtained Tt values just before each MR examination to evaluate the relationships among the three temperatures. There were significant positive correlations between Tv and Tp (R = 0.611, p < 0.001). The correlation was also significant after correction for Tt (R = 0.642, p < 0.001). There was no significant correlation between Tv and Tt or between Tp and Tt in the men or the women. Negative correlations were found between Tv and age and between Tp and age in the males but not females. DWI thermometry seems to reflect the intracranial environment as accurately as MRS thermometry. An age-dependent decline in temperature was evident in our male subjects by both DWI and MRS thermometry, probably due to the decrease in cerebral metabolism with age. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27129076

  8. Diffusion Weighted MR Imaging of Primary and Recurrent Middle Ear Cholesteatoma: An Assessment by Readers with Different Expertise

    PubMed Central

    Elefante, A.; Cavaliere, M.; Russo, C.; Caliendo, G.; Marseglia, M.; Cicala, D.; Piccolo, D.; Di Lullo, A.; Brunetti, L.; Palma, A.; Iengo, M.; Brunetti, A.

    2015-01-01

    Introduction and Purpose. Diffusion weighted imaging (DWI) has been proven to be valuable in the diagnosis of middle ear cholesteatoma. The aims of our study were to evaluate the advantage of multi-shot turbo spin echo (MSh TSE) DWI compared to single-shot echo-planar (SSh EPI) DWI for the diagnosis of cholesteatoma. Material and Methods. Thirty-two patients with clinical suspicion of unilateral cholesteatoma underwent preoperative MRI (1.5T) with SSh EPI and MSh TSE. Images were separately analyzed by 4 readers with different expertise to confirm the presence of cholesteatoma. Sensitivity, specificity, diagnostic accuracy, and positive (PPV) and negative predictive values (NPV) were assessed for each observer and interrater agreement was assessed using kappa statistics. Diagnosis was obtained at surgery. Results. Overall MSh TSE showed higher diagnostic accuracy and lower negative predictive value (NPV) compared to conventional SSh EPI. Interreader agreement between the observers revealed the superiority of MSh TSE compared to SSh EPI. Interrater agreement among all the four observers was higher by using MSh TSE compared to SSh EPI. Conclusion. Our findings suggest that MSh TSE DWI has higher sensitivity for detection of cholesteatoma and lower probability of misdiagnosis. MSh TSE DWI is useful in guiding less experienced observers to the diagnosis. PMID:25722983

  9. Silent cerebral emboli following percutaneous closure of atrial septal defect in pediatric patients: a diffusion-weighted MRI study

    PubMed Central

    Koç, Gonca; Özyurt, Abdullah; Doğanay, Selim; Baykan, Ali; Görkem, S. Burcu; Doğan, M. Sait; Pamukçu, Özge; Üzüm, Kazım; Coşkun, Abdulhakim; Narin, Nazmi

    2016-01-01

    PURPOSE The aim of this prospective study was to investigate the incidence of silent cerebrovascular embolic events associated with percutaneous closure of atrial septal defect (ASD) in pediatric patients. METHODS A total of 23 consecutive pediatric patients (mean age, 10.4±3.8 years; range, 4–17 years) admitted for transcatheter closure of ASD were recruited in the study. The patients were scanned with a 1.5 Tesla clinical scanner. Two cranial magnetic resonance imaging (MRI) examinations were acquired before the procedure and within 24 hours following the catheterization. MRI included turbo spin-echo fluid-attenuated inversion recovery (FLAIR) sequence and diffusion-weighted imaging technique with single-shot echo-planar spin-echo sequence. The transcatheter closure of ASD was performed by three expert interventional cardiologists. Amplatzer septal occluder device was implemented for the closure of the defect. No contrast medium was administered in the course of the procedure. RESULTS None of the patients had diffusion restricted cerebral lesions resembling microembolic infarctions on postprocedural MRI. Preprocedural MRI of two patients revealed nonspecific hyperintense white matter lesions on FLAIR images with increased diffusion, which were considered to be older ischemic lesions associated with previously occurred paradoxical embolism. CONCLUSION The current study suggests that percutaneous closure of the ASD, when performed by experienced hands, may be free of cerebral microembolization in pediatric patients. However, due to the relatively small sample size, further studies with larger patient groups are needed for the validation of our preliminary results. PMID:26394443

  10. Phantom for assessment of fat suppression in large field-of-view diffusion-weighted magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Winfield, J. M.; Douglas, N. H. M.; deSouza, N. M.; Collins, D. J.

    2014-05-01

    We present the development and application of a phantom for assessment and optimization of fat suppression over a large field-of-view in diffusion-weighted magnetic resonance imaging at 1.5 T and 3 T. A Perspex cylinder (inner diameter 185 mm, height 300 mm) which contains a second cylinder (inner diameter 140 mm) was constructed. The inner cylinder was filled with water doped with copper sulphate and sodium chloride and the annulus was filled with corn oil, which closely matches the spectrum and longitudinal relaxation times of subcutaneous abdominal fat. Placement of the phantom on the couch at 45° to the z-axis presented an elliptical cross-section, which was of a similar size and shape to axial abdominal images. The use of a phantom for optimization of fat suppression allowed quantitative comparison between studies without the differences introduced by variability between human subjects. We have demonstrated that the phantom is suitable for selection of inversion delay times, spectral adiabatic inversion recovery delays and assessment of combinatorial methods of fat suppression. The phantom is valuable in protocol development and the assessment of new techniques, particularly in multi-centre trials.

  11. ROBUST FAT SUPPRESSION AT 3T IN HIGH-RESOLUTION DIFFUSION-WEIGHTED SINGLE-SHOT EPI OF HUMAN BRAIN

    PubMed Central

    Sarlls, Joelle E.; Pierpaoli, Carlo; Talagala, S. Lalith; Luh, Wen-Ming

    2011-01-01

    Single-shot EPI is the most common acquisition technique for whole-brain diffusion tensor imaging (DTI) studies in vivo. Higher field MRI systems are readily available and advantageous for acquiring DTI due to increased signal. One of the practical issues for DTI with single-shot EPI at high field is incomplete fat suppression resulting in a chemically-shifted fat artifact within the brain image. Unsuppressed fat is especially detrimental in DTI because the diffusion coefficient of fat is two orders of magnitude lower than that of parenchyma, producing brighter appearing fat artifacts with greater diffusion weighting. In this work, several fat suppression techniques were tested alone and in combination with the goal of finding a method that provides robust fat suppression and can be utilized in high-resolution single-shot EPI DTI studies. Combination of chemical shift saturation with slice-select gradient reversal within a dual-spin-echo diffusion preparation period was found to provide robust fat suppression at 3T. PMID:21604298

  12. Diffusion-Weighted Magnetic Resonance Application in Response Prediction before, during, and after Neoadjuvant Radiochemotherapy in Primary Rectal Cancer Carcinoma

    PubMed Central

    Musio, Daniela; De Felice, Francesca; Magnante, Anna Lisa; Rengo, Marco; Redler, Adriano; Laghi, Andrea; Raffetto, Nicola; Tombolini, Vincenzo

    2013-01-01

    Introduction. Our interest was to monitor treatment response using ADC value to predict response of rectal tumour to preoperative radiochemotherapy. Materials and Methods. Twenty-two patients were treated with long course of radiochemotherapy, followed by surgery. Patients were examined by diffusion-weighted imaging MRI at three-time points (prior, during, and after radiochemotherapy) and were classified as responders and nonresponders. Results. A statistical significant correlation was found between preradiochemotherapy ADC values and during treatment ADC values, in responders (F = 21.50, P value <0.05). An increase in ADC value during treatment was predictive of at least a partial response. Discussion. Response of tumour to neoadjuvant therapy cannot be easily evaluated, and such capability might be of great importance in clinical practice, because the number of irradiated and operated patients may be superior to the number of who will really benefit from this multimodal treatment. A reliable prediction of the final clinical TN stage would allow radiotherapist to adapt multidisciplinary approach to a less invasive management, sparing surgical procedure in responder patients or even allowing an early surgery in nonresponders, which would significantly reduce radiochemotherapy related toxicity. Conclusion. Early evaluation of response during neoadjuvant radiochemotherapy treatment shows great promise to predict tumour response. PMID:23936841

  13. Multivariate General Linear Models (MGLM) on Riemannian Manifolds with Applications to Statistical Analysis of Diffusion Weighted Images

    PubMed Central

    Kim, Hyunwoo J.; Adluru, Nagesh; Collins, Maxwell D.; Chung, Moo K.; Bendlin, Barbara B.; Johnson, Sterling C.; Davidson, Richard J.; Singh, Vikas

    2014-01-01

    Linear regression is a parametric model which is ubiquitous in scientific analysis. The classical setup where the observations and responses, i.e., (xi, yi) pairs, are Euclidean is well studied. The setting where yi is manifold valued is a topic of much interest, motivated by applications in shape analysis, topic modeling, and medical imaging. Recent work gives strategies for max-margin classifiers, principal components analysis, and dictionary learning on certain types of manifolds. For parametric regression specifically, results within the last year provide mechanisms to regress one real-valued parameter, xi ∈ R, against a manifold-valued variable, yi ∈ . We seek to substantially extend the operating range of such methods by deriving schemes for multivariate multiple linear regression —a manifold-valued dependent variable against multiple independent variables, i.e., f : Rn → . Our variational algorithm efficiently solves for multiple geodesic bases on the manifold concurrently via gradient updates. This allows us to answer questions such as: what is the relationship of the measurement at voxel y to disease when conditioned on age and gender. We show applications to statistical analysis of diffusion weighted images, which give rise to regression tasks on the manifold GL(n)/O(n) for diffusion tensor images (DTI) and the Hilbert unit sphere for orientation distribution functions (ODF) from high angular resolution acquisition. The companion open-source code is available on nitrc.org/projects/riem_mglm. PMID:25580070

  14. Thymoma of the left thymic lobe with a contralateral small pleural implant successfully detected with diffusion-weighted MRI.

    PubMed

    Priola, Adriano Massimiliano; Priola, Sandro Massimo

    2015-01-01

    Thymoma is the most common primary neoplasm of the anterior mediastinum. At diagnosis, up to 40% of patients present with advanced disease. Because advanced thymomas receive neoadjuvant chemotherapy, diagnostic imaging is crucial to plan the correct treatment. For characterizing thymomas, CT is the first choice modality, whereas 18F-FDG/PET is reserved for questionable cases and MRI is not routinely employed. Hereby, we describe a case of thymoma with a single contralateral pleural implant in a 30-year-old woman. The small pleural thickening detected at CT was correctly interpreted as pleural seeding related to thymoma at diffusion-weighted (DW)-MRI after a negative 18F-FDG/PET scan, and was subsequently confirmed at surgery. Precise diagnosis and accurate preoperative staging are crucial in managing thymic epithelial tumours in order to design the appropriate treatment and improve prognosis. Indeed, when stage IVa for pleural seeding is diagnosed preoperatively, a multimodality approach including primary chemotherapy followed by surgery and postoperative radiotherapy/chemotherapy is recommended. This is the first report that used DW-MRI for the characterization of pleural seeding in thymoma and demonstrates that DW-MRI could be useful for the correct pre-operatory staging in thymoma patients, especially in cases with indeterminate pleural thickenings at CT, in order to define the correct management. PMID:25702681

  15. Diffusion-weighted imaging and dynamic contrast-enhanced MRI in assessing response and recurrent disease in gynaecological malignancies.

    PubMed

    Hameeduddin, Ayshea; Sahdev, Anju

    2015-01-01

    Magnetic resonance imaging (MRI) has an established role in imaging pelvic gynaecological malignancies. It is routinely used in staging endometrial and cervical cancer, characterizing adnexal masses, selecting optimal treatment, monitoring treatment and detecting recurrent disease. MRI has also been shown to have an excellent performance and an evolving role in surveillance of patients after chemoradiotherapy in cervical cancer, post-trachelectomy, detecting early recurrence and planning exenterative surgery in isolated central recurrences in both cervical and endometrial cancer and in young patients on surveillance for medically managed endometrial cancer. However, conventional MRI still has limitations when the morphological appearance of early recurrent or residual disease overlaps with normal pelvic anatomy or treatment effects in the pelvis. In particular, after chemoradiotherapy for cervical cancer, distinguishing between radiotherapy changes and residual or early recurrent disease within the cervix or the vaginal vault can be challenging on conventional MRI alone. Therefore, there is an emerging need for functional imaging to overcome these limitations. The purpose of this paper is to discuss the emerging functional MRI techniques and their applications in predicting treatment response, detecting residual disease and early recurrent disease to optimize the treatment options available using diffusion-weighted imaging and dynamic contrast enhancement particularly in cervical and endometrial cancer. PMID:25889065

  16. [Aspects of FLAIR sequences, 3D-CISS and diffusion-weight MR imaging of intracranial epidermoid cysts].

    PubMed

    Doll, A; Abu Eid, M; Kehrli, P; Esposito, P; Gillis, C; Bogorin, A; Jacques, C; Dietemann, J L

    2000-06-01

    We propose to assess the usefulness of diffusion-weighted MR Imaging (DWI), fluid-attenuated inversion recovery (FLAIR) and constructive interference in steady state (CISS) sequences in depicting epidermoid cysts (EC). FLAIR, CISS and DWI were obtained in 7 patients among 22. All patients were studied with T1 and T2 sequences. On Spin Echo images, EC demonstrate signal similar to LCS, which may lead to difficult differentiation between EC and arachnoid cyst (AC), specially for inexperienced radiologists. EC appear with a heterogeneous signal on T1 images (32%), irregular limits (91%) and with extension through foramen of Pacchioni in 18% of cases. On FLAIR sequence, the tumors were heterogeneous, different from void signal of CSF in 86% of cases. On CISS sequence, the tumors appear heterogeneous, hyperintense but less than LCS and with irregular limits in all cases. Some more, CISS images allowed to appreciate exact tumor extension and their relations with nerves and vessels. On DWI images, signal is hyperintense in all cases. Our study exhibited the great usefulness of DWI, CISS and FLAIR sequences in diagnosis of EC and in differentiating EC from AC. PMID:10970961

  17. Confirmation of functional zones within the human subthalamic nucleus: Patterns of connectivity and sub-parcellation using diffusion weighted imaging

    PubMed Central

    Lambert, Christian; Zrinzo, Ludvic; Nagy, Zoltan; Lutti, Antoine; Hariz, Marwan; Foltynie, Thomas; Draganski, Bogdan; Ashburner, John; Frackowiak, Richard

    2012-01-01

    The subthalamic nucleus (STN) is a small, glutamatergic nucleus situated in the diencephalon. A critical component of normal motor function, it has become a key target for deep brain stimulation in the treatment of Parkinson's disease. Animal studies have demonstrated the existence of three functional sub-zones but these have never been shown conclusively in humans. In this work, a data driven method with diffusion weighted imaging demonstrated that three distinct clusters exist within the human STN based on brain connectivity profiles. The STN was successfully sub-parcellated into these regions, demonstrating good correspondence with that described in the animal literature. The local connectivity of each sub-region supported the hypothesis of bilateral limbic, associative and motor regions occupying the anterior, mid and posterior portions of the nucleus respectively. This study is the first to achieve in-vivo, non-invasive anatomical parcellation of the human STN into three anatomical zones within normal diagnostic scan times, which has important future implications for deep brain stimulation surgery. PMID:22173294

  18. Bidirectional iterative parcellation of diffusion weighted imaging data: Separating cortical regions connected by the arcuate fasciculus and extreme capsule

    PubMed Central

    Patterson, Dianne K.; Van Petten, Cyma; Beeson, Pélagie M.; Rapcsak, Steven Z.; Plante, Elena

    2014-01-01

    This paper introduces a Bidirectional Iterative Parcellation (BIP) procedure designed to identify the location and size of connected cortical regions (parcellations) at both ends of a white matter tract in diffusion weighted images. The procedure applies the FSL option “probabilistic tracking with classification targets” in a bidirectional and iterative manner. To assess the utility of BIP, we applied the procedure to the problem of parcellating a limited set of well-established gray matter seed regions associated with the dorsal (arcuate fasciculus/superior longitudinal fasciculus) and ventral (extreme capsule fiber system) white matter tracts in the language networks of 97 participants. These left hemisphere seed regions and the two white matter tracts, along with their right hemisphere homologues, provided an excellent test case for BIP because the resulting parcellations overlap and their connectivity via the arcuate fasciculi and extreme capsule fiber systems are well studied. The procedure yielded both confirmatory and novel findings. Specifically, BIP confirmed that each tract connects within the seed regions in unique, but expected ways. Novel findings included increasingly left-lateralized parcellations associated with the arcuate fasciculus/superior longitudinal fasciculus as a function of age and education. These results demonstrate that BIP is an easily implemented technique that successfully confirmed cortical connectivity patterns predicted in the literature, and has the potential to provide new insights regarding the architecture of the brain. PMID:25173414

  19. TU-C-12A-05: Repeatability Study of Reduced Field-Of-View Diffusion-Weighted MRI On Human Thyroid Gland

    SciTech Connect

    Shukla-Dave, A; Lu, Y; Hatzoglou, V; Stambuk, H; Mazaheri, Y; Banerjee, S; Shankaranarayanan, A; Deasy, J

    2014-06-15

    Purpose: To investigate the repeatability of reduced field-of-view diffusion-weighted imaging (rFOV DWI) in quantifying apparent diffusion coefficients (ADCs) for human thyroid glands in a clinical setting. Methods: Nine healthy human volunteers were enrolled and underwent 3T MRI exams. For each volunteer, 3 longitudinal exams (2 weeks apart) with 2 repetitive sessions within each exam, including rFOV and conventional full field-of-view (fFOV) DWI scans, were performed. In the acquired DWI images, a fixed-size region of interest (ROI; diameter=8mm) was placed on thyroid glands to calculate ADC. ADC was calculated using a monoexponential function with a noise correction scheme. The repeatability of ADC was assessed by using coefficient variation (CV) across sessions or exams, which was defined to be: r = 1-CV, 0 < r < 1, where CV=STD/m, STD is the standard deviation of ADC, and m is the average of ADC across sessions or exams. An experienced radiologist assessed and scored rFOV and fFOV DW images based on image characteristics (1, nondiagnostic; 2, poor; 3, satisfactory; 4, good; and 5, excellent).Analysis of variance (ANOVA) was performed to compare ADC values, CV of ADC, repeatability of ADC across sessions and exams, and radiologic scores between rFOV and fFOV DWI techniques. Results: There was no significant difference in ADC values across sessions and exams either in rFOV or fFOV DWI. The average CVs of both rFOV and fFOV DWI were less than 13%. The repeatability of ADC measurement between rFOV and fFOV DWI was not significantly different. The overall image quality was significantly higher with rFOV DWI than with fFOV DWI. Conclusion: This study suggested that ADCs from both rFOV and fFOV DWI were repeatable, but rFOV DWI had superior imaging quality for human thyroid glands in a clinical setting.

  20. Diffusion-weighted EPI- and HASTE-MRI and 18F-FDG-PET-CT early during chemoradiotherapy in advanced head and neck cancer

    PubMed Central

    Schouten, Charlotte S.; de Bree, Remco; van der Putten, Lisa; Noij, Daniel P.; Hoekstra, Otto S.; Comans, Emile F.I.; Witte, Birgit I.; Doornaert, Patricia A.; Leemans, C. René

    2014-01-01

    Main problem Diffusion-weighted MRI (DW-MRI) has potential to predict chemoradiotherapy (CRT) response in head and neck squamous cell carcinoma (HNSCC) and is generally performed using echo-planar imaging (EPI). However, EPI-DWI is susceptible to geometric distortions. Half-fourier acquisition single-shot turbo spin-echo (HASTE)-DWI may be an alternative. This prospective pilot study evaluates the potential predictive value of EPI- and HASTE-DWI and 18F-fluorodeoxyglucose PET-CT (18F-FDG-PET-CT) early during CRT for locoregional outcome in HNSCC. Methods Eight patients with advanced HNSCC (7 primary tumors and 25 nodal metastases) scheduled for CRT, underwent DW-MRI (using both EPI- and HASTE-DWI) and 18F-FDG-PET(-CT) pretreatment, early during treatment and three months after treatment. Median follow-up time was 38 months. Results No local recurrences were detected during follow-up. Median Apparent Diffusion Coefficient (ADC)EPI-values in primary tumors increased from 77×10–5 mm2/s pretreatment, to 113×10–5 mm2/s during treatment (P=0.02), whereas ADCHASTE did not increase (74 and 74 mm2/s, respectively). Two regional recurrences were diagnosed. During treatment, ADCEPI tended to be higher for patients with regional control [(117.3±12.1)×10–5 mm2/s] than for patients with a recurrence [(98.0±4.2)×10–5 mm2/s]. This difference was not seen with ADCHASTE. No correlations between ΔADCEPI and ΔSUV (Standardized Uptake Value) were found in the primary tumor or nodal metastases. Conclusions HASTE-DWI seems to be inadequate in early CRT response prediction, compared to EPI-DWI which has potential to predict locoregional outcome. EPI-DWI and 18F-FDG-PET-CT potentially provide independent information in the early response to treatment, since no correlations were found between ΔADCEPI and ΔSUV. PMID:25202659

  1. Quantitative Sodium MR Imaging at 7 T: Initial Results and Comparison with Diffusion-weighted Imaging in Patients with Breast Tumors.

    PubMed

    Zaric, Olgica; Pinker, Katja; Zbyn, Stefan; Strasser, Bernhard; Robinson, Simon; Minarikova, Lenka; Gruber, Stephan; Farr, Alex; Singer, Christian; Helbich, Thomas H; Trattnig, Siegfried; Bogner, Wolfgang

    2016-07-01

    Purpose To investigate the clinical feasibility of a quantitative sodium 23 ((23)Na) magnetic resonance (MR) imaging protocol developed for breast tumor assessment and to compare it with 7-T diffusion-weighted imaging (DWI). Materials and Methods Written informed consent in this institutional review board-approved study was obtained from eight healthy volunteers and 17 patients with 20 breast tumors (five benign, 15 malignant). To achieve the best image quality and reproducibility, the (23)Na sequence was optimized and tested on phantoms and healthy volunteers. For in vivo quantification of absolute tissue sodium concentration (TSC), an external phantom was used. Static magnetic field, or B0, and combined transmit and receive radiofrequency field, or B1, maps were acquired, and image quality, measurement reproducibility, and accuracy testing were performed. Bilateral (23)Na and DWI sequences were performed before contrast material-enhanced MR imaging in patients with breast tumors. TSC and apparent diffusion coefficient (ADC) were calculated and correlated for healthy glandular tissue and benign and malignant lesions. Results The (23)Na MR imaging protocol is feasible, with 1.5-mm in-plane resolution and 16-minute imaging time. Good image quality was achieved, with high reproducibility (mean TSC values ± standard deviation for the test, 36 mmol per kilogram of wet weight ± 2 [range, 34-37 mmol/kg]; for the retest, 37 mmol/kg ± 1 [range, 35-39 mmol/kg]; P = .610) and accuracy (r = 0.998, P < .001). TSC values in normal glandular and adipose breast tissue were 35 mmol/kg ± 3 and 18 mmol/kg ± 3, respectively. In malignant lesions (mean size, 31 mm ± 24; range, 6-92 mm), the TSC of 69 mmol/kg ± 10 was, on average, 49% higher than that in benign lesions (mean size, 14 mm ± 12; range, 6-35 mm), with a TSC of 47 mmol/kg ± 8 (P = .002). There were similar ADC differences between benign ([1.78 ± 0.23] × 10(-3) mm(2)/sec) and malignant ([1.03 ± 0.23] × 10(-3) mm

  2. Quantitative diffusion-weighted magnetic resonance imaging in the assessment of myocardial fibrosis in hypertrophic cardiomyopathy compared with T1 mapping.

    PubMed

    Wu, Lian-Ming; Chen, Bing-Hua; Yao, Qiu-Ying; Ou, Yang-Rongzheng; Wu, Rui; Jiang, Meng; Hu, Jiani; An, Dong-Aolei; Xu, Jian-Rong

    2016-08-01

    To identify myocardial fibrosis in hypertrophic cardiomyopathy (HCM) subjects using quantitative cardiac diffusion-weighted imaging (DWI) and to compare its performance with native T1 mapping and extracellular volume (ECV). Thirty-eight HCM subjects (mean age, 53 ± 9 years) and 14 normal controls (mean age, 51 ± 8 years) underwent cardiac magnetic resonance imaging (CMRI) on a 3.0T magnetic resonance (MR) machine with DWI, T1 mapping and late gadolinium enhancement (LGE) imaging as the reference standard. The mean apparent diffusion coefficient (ADC), native T1 value and ECV were determined for each subject. Overall, the HCM subjects exhibited an increased native T1 value (1241.04 ± 78.50 ms), ECV (0.31 ± 0.03) and ADC (2.36 ± 0.34 s/mm(2)) compared with the normal controls (1114.60 ± 37.99 ms, 0.24 ± 0.04, and 1.62 ± 0.38 s/mm(2), respectively) (p < 0.05). DWI differentiated healthy and fibrotic myocardia with an area under the curve (AUC) of 0.93, while the AUCs of the native T1 values (0.93), (p > 0.05) and ECV (0.94), (p > 0.05) exhibited an equal differentiation ability. Both HCM LGE+ and HCM LGE- subjects had an increased native T1 value, ECV and ADC compared to the normal controls (p < 0.05). HCM LGE+ subjects exhibited an increased ECV (0.31 ± 0.04) and ADC (2.43 ± 0.36 s/mm(2)) compared to HCM LGE- subjects (p < 0.05). HCM LGE+ and HCM LGE- subjects had similar native T1 values (1250 ± 76.36 ms vs. 1213.98 ± 92.30 ms, respectively) (p > 0.05). ADC values were linearly associated with increased ECV (R(2) = 0.36) and native T1 values (R(2) = 0.40) among all subjects. DWI is a feasible alternative to native T1 mapping and ECV for the identification of myocardial fibrosis in patients with HCM. DWI and ECV can quantitatively characterize the extent of fibrosis in HCM LGE+ and HCM LGE- patients. PMID:27198892

  3. Assessing the Early Response of Advanced Cervical Cancer to Neoadjuvant Chemotherapy Using Intravoxel Incoherent Motion Diffusion-weighted Magnetic Resonance Imaging: A Pilot Study

    PubMed Central

    Wang, Yan-Chun; Hu, Dao-Yu; Hu, Xue-Mei; Shen, Ya-Qi; Meng, Xiao-Yan; Tang, Hao; Li, Zhen

    2016-01-01

    Background: Diffusion-weighted imaging (DWI) with the intravoxel incoherent motion (IVIM) model has shown promising results for providing both diffusion and perfusion information in cervical cancer; however, its use to predict and monitor the efficacy of neoadjuvant chemotherapy (NACT) in cervical cancer is relatively rare. The study aimed to evaluate the use of DWI with IVIM and monoexponential models to predict and monitor the efficacy of NACT in cervical cancer. Methods: Forty-two patients with primary cervical cancer underwent magnetic resonance exams at 3 time points (pre-NACT, 3 weeks after the first NACT cycle, and 3 weeks after the second NACT cycle). The response to treatment was determined according to the response evaluation criteria in solid tumors 3 weeks after the second NACT treatment, and the subjects were classified as two groups: responders and nonresponders groups. The apparent diffusion coefficient (ADC), true diffusion coefficient (D), perfusion-related pseudo-diffusion coefficient (D*), and perfusion fraction (f) values were determined. The differences in IVIM-derived variables and ADC between the different groups at the different time points were calculated using an independent samples t-test. Results: The D and ADC values were all significantly higher for the responders than for the nonresponders at all 3 time points, but no significant differences were observed in the D* and f values. An analysis of the receiver operating characteristic (ROC) curves indicated that a D value threshold <0.93 × 10−3 mm2/s and an ADC threshold <1.11 × 10−3 mm2/s could differentiate responders from nonresponders at pre-NACT time point, yielding area under the curve (AUC) of which were 0.771 and 0.806, respectively. The ROC indicated that the AUCs of D and ADC at the 3 weeks after the first NACT cycle and 3 weeks after the second NACT cycle were 0.823, 0.763, and 0.787, 0.794, respectively. The AUC values of D and ADC at these 3 time points were not

  4. Potential of Diffusion-Weighted Imaging in the Characterization of Malignant, Benign, and Healthy Breast Tissues and Molecular Subtypes of Breast Cancer

    PubMed Central

    Sharma, Uma; Sah, Rani G.; Agarwal, Khushbu; Parshad, Rajinder; Seenu, Vurthaluru; Mathur, Sandeep R.; Hari, Smriti; Jagannathan, Naranamangalam R.

    2016-01-01

    The role of apparent diffusion coefficient (ADC) in the diagnosis of breast cancer and its association with molecular biomarkers was investigated in 259 patients with breast cancer, 67 with benign pathology, and 54 healthy volunteers using diffusion-weighted imaging (DWI) at 1.5 T. In 59 breast cancer patients, dynamic contrast-enhanced MRI (DCEMRI) was also acquired. Mean ADC of malignant lesions was significantly lower (1.02 ± 0.17 × 10−3 mm2/s) compared to benign (1.57 ± 0.26 × 10−3 mm2/s) and healthy (1.78 ± 0.13 × 10−3 mm2/s) breast tissues. A cutoff ADC value of 1.23 × 10−3 mm2/s (sensitivity 92.5%; specificity 91.1%; area under the curve 0.96) to differentiate malignant from benign diseases was arrived by receiver operating curve analysis. In 10/59 breast cancer patients, indeterminate DCE curve was seen, while their ADC value was indicative of malignancy, implying the potential of the addition of DWI in increasing the specificity of DCEMRI data. Further, the association of ADC with tumor volume, stage, hormonal receptors [estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor (HER2)], and menopausal status was investigated. A significant difference was seen in tumor volume between breast cancer patients of stages IIA and IIIA, IIB and IIIA, and IIB and III (B + C), respectively (P < 0.05). Patients with early breast cancer (n = 52) had significantly lower ADC and tumor volume than those with locally advanced breast cancer (n = 207). No association was found in ADC and tumor volume with the menopausal status. Breast cancers with ER−, PR−, and triple-negative (TN) status showed a significantly larger tumor volume compared to ER+, PR+, and non-triple-negative (nTN) cancers, respectively. Also, TN tumors showed a significantly higher ADC compared to ER+, PR+, and nTN cancers. Patients with ER− and TN cancers were younger than those with ER+ and nTN cancers

  5. Preoperative Diagnostic Strategy for Parotid Gland Tumors Using Diffusion-Weighted MRI and Technetium-99m Pertechnetate Scintigraphy: A Prospective Study

    PubMed Central

    Kikuchi, Masahiro; Koyasu, Sho; Shinohara, Shogo; Imai, Yukihiro; Hino, Megumu; Naito, Yasushi

    2016-01-01

    Objective Fine needle aspiration cytology (FNAC) for diagnosis of a parotid gland tumor is widely used but its sensitivity is low and non-diagnostic rate is relatively high. In contrast, core needle biopsy (CNB) has a higher sensitivity and lower rate of sampling errors but has a higher risk of injury to adjacent organs such as facial nerve than FNAC. Screening of patients with parotid gland tumors to identify cases of pleomorphic adenoma (PA) and Warthin tumor (WT) may allow CNB to be confined to patients without PA and WT. We established an algorithm for preoperative diagnosis and management of parotid gland tumor using diffusion-weighted MRI and 99mTc pertechnetate scintigraphy. This algorithm was developed with the goal of maximal reduction of the number of patients in whom CNB is required. The purpose of the study is to validate our algorithm prospectively. Methods A prospective study was conducted in 71 cases who were newly diagnosed with parotid gland tumor and 53 cases were enrolled in the study. In the algorithm, PA (high apparent diffusion coefficient (ADC) mean≥1.5×10−3 mm2/s) and non-PA (low ADCmean<1.5×10−3 mm2/s) cases are first distinguished based on the ADCmean on diffusion-weighed MRI. Second, among suspected non-PA cases, WT and non-WT are distinguished using technetium-99m pertechnetate scintigraphy. CNB is then performed only in probable non-PA and non-WT cases. Results Although CNB was only required in 40% (21/53) of all cases, we made a preoperative histopathological diagnosis with an accuracy of 87% (46/53) and we correctly diagnosed whether a tumor was benign or malignant with an accuracy of 96% (51/53). Preoperative surgical planning had to be changed during surgery in only one case (2%) Conclusions Our algorithm is valuable in terms of clinical practice with highly potential for preoperative diagnosis and with less risk of CNB procedure. PMID:26849569

  6. Value of the Diffusion-Weighted MRI in the Differential Diagnostics of Malignant and Benign Kidney Neoplasms – Our Clinical Experience

    PubMed Central

    Mytsyk, Yulian; Borys, Yuriy; Komnatska, Iryna; Dutka, Ihor; Shatynska-Mytsyk, Iryna

    2014-01-01

    Summary Background Diffusion-weighted imaging (DWI) is an MRI modality using strong bipolar gradients to create a sensitivity of the signal to the thermally-induced Brownian motions of water molecules and in vivo measurement of molecular diffusion. The apparent diffusion coefficient (ADC) is a quantitative parameter calculated from DWI images which is used as a measure of diffusion. DWI allows to obtain comprehensive information on morphological and functional state of the kidney during a single examination without contrast medium administration. The purpose of the study was to evaluate the value of DWI in differentiating benign and malignant solid kidney tumors based on the initial stage of the study. Material/Methods The study included 19 adult patients with pathologically verified renal tumors: 9 patients with clear cell subtype of the renal cell carcinoma, 5 patients with oncocytoma and 5 patients with angiomyolipoma (AML). In addition, 5 healthy volunteers with completely normal findings according to kidney ultrasound were included into this study and set as reference. All patients underwent renal MR imaging which included DWI with subsequent ADC measurement. MR imaging was performed with a 1.5 T body scanner using an eight-channel phased-array body coil. Results The mean ADC value of ccRCC was significantly lower than that of normal renal parenchyma (2.11±0.25×10−3 mm2/s vs. 3.36±0.41×10−3 mm2/s, p<0.01). There was a significant difference in ADC between the malignant and benign renal lesions: in patients with angiomyolipoma the ADC value was 2.36±0.32×10−3 mm2/s vs. 2.11±0.25×10−3 mm2/s; p<0.05 and in patients with oncocytoma – 2.75±0.27×10−3 mm2/s vs. 2.11±0.25×10−3 mm2/s; p<0.05. The difference in ADC values in patients with high and low ccRCC grades was observed. Conclusions DWI can be used to characterize renal lesions; the ADC of a renal lesion can be potentially used as an additional parameter to help determine the appropriate

  7. Characteristics of liver on magnetic resonance diffusion-weighted imaging: Dynamic and image pathological investigation in rabbit liver VX-2 tumor model

    PubMed Central

    Yuan, You-Hong; Xiao, En-Hua; Liu, Jian-Bin; He, Zhong; Jin, Ke; Ma, Cong; Xiang, Jun; Xiao, Jian-Hua; Chen, Wei-Jian

    2008-01-01

    AIM: To investigate dynamical and image pathological characteristics of the liver on magnetic resonance (MR) diffusion-weighted imaging (DWI) in the rabbit VX-2 tumor model. METHODS: Forty New Zealand rabbits were included in the study and VX-2 tumor piece was implanted intrahepatically. Fifteen animals received two intrahepatic implantations while 25 had one intrahepatical implantation. DWI, T1- and T2-weighted of magnetic resonance imaging (MRI) were carried out on the 7th and the 14th d after implantation and DWI was conducted, respectively on the 21th d. Ten VX-2 tumor samples were studied pathologically. RESULTS: The rate of lump detected by DWI, T1WI and T2WI was 78.7%, 10.7% and 53.5% (χ2 = 32.61, P < 0.001) on the 7th d after implantation and 95.8%, 54.3% and 82.9% (χ2 = 21.50, P < 0.001) on the 14th d. The signal of most VX-2 tumors on DWI was uniform and it was equal on the map of apparent diffusion coefficient (ADC). The signal of VX tumors did not decrease on the 7th d after implantation, most of them slowly growing during the week following implantation without significant cell dying within the tumor. VX-2 tumors grew increasingly within 14 d after implantation but the signal of most VX-2 tumors on DWI or on the map of ADC was uniform or uneven and ADC of VX tumors decreased obscurely or slightly because tumor necrosis was still not obvious. On the 21th d after implantation, the signal of most VX-2 tumors on DWI or on the map of ADC was uneven because tumor necrosis was evident and ADC of VX-2 tumor necrotic areas decreased. The areas of viable cells in VX-2 tumors manifested a high signal on DWI and a low signal on the map of ADC. The areas of dead cells or necrosis in VX-2 tumors manifested low signals on DWI and low, equal or high signals on the map of ADC but they manifested high signals on DWI and on the map of ADC at the same time when the areas of necrotic tumor became liquefied or cystic. The border of tumors on DWI appeared gradually

  8. Potential of Diffusion-Weighted Imaging in the Characterization of Malignant, Benign, and Healthy Breast Tissues and Molecular Subtypes of Breast Cancer.

    PubMed

    Sharma, Uma; Sah, Rani G; Agarwal, Khushbu; Parshad, Rajinder; Seenu, Vurthaluru; Mathur, Sandeep R; Hari, Smriti; Jagannathan, Naranamangalam R

    2016-01-01

    The role of apparent diffusion coefficient (ADC) in the diagnosis of breast cancer and its association with molecular biomarkers was investigated in 259 patients with breast cancer, 67 with benign pathology, and 54 healthy volunteers using diffusion-weighted imaging (DWI) at 1.5 T. In 59 breast cancer patients, dynamic contrast-enhanced MRI (DCEMRI) was also acquired. Mean ADC of malignant lesions was significantly lower (1.02 ± 0.17 × 10(-3) mm(2)/s) compared to benign (1.57 ± 0.26 × 10(-3) mm(2)/s) and healthy (1.78 ± 0.13 × 10(-3) mm(2)/s) breast tissues. A cutoff ADC value of 1.23 × 10(-3) mm(2)/s (sensitivity 92.5%; specificity 91.1%; area under the curve 0.96) to differentiate malignant from benign diseases was arrived by receiver operating curve analysis. In 10/59 breast cancer patients, indeterminate DCE curve was seen, while their ADC value was indicative of malignancy, implying the potential of the addition of DWI in increasing the specificity of DCEMRI data. Further, the association of ADC with tumor volume, stage, hormonal receptors [estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor (HER2)], and menopausal status was investigated. A significant difference was seen in tumor volume between breast cancer patients of stages IIA and IIIA, IIB and IIIA, and IIB and III (B + C), respectively (P < 0.05). Patients with early breast cancer (n = 52) had significantly lower ADC and tumor volume than those with locally advanced breast cancer (n = 207). No association was found in ADC and tumor volume with the menopausal status. Breast cancers with ER-, PR-, and triple-negative (TN) status showed a significantly larger tumor volume compared to ER+, PR+, and non-triple-negative (nTN) cancers, respectively. Also, TN tumors showed a significantly higher ADC compared to ER+, PR+, and nTN cancers. Patients with ER- and TN cancers were younger than those with ER+ and n

  9. Co-analysis of Brain Structure and Function using fMRI and Diffusion-weighted Imaging

    PubMed Central

    Phillips, Jeffrey S.; Greenberg, Adam S.; Pyles, John A.; Pathak, Sudhir K.; Behrmann, Marlene; Schneider, Walter; Tarr, Michael J.

    2012-01-01

    The study of complex computational systems is facilitated by network maps, such as circuit diagrams. Such mapping is particularly informative when studying the brain, as the functional role that a brain area fulfills may be largely defined by its connections to other brain areas. In this report, we describe a novel, non-invasive approach for relating brain structure and function using magnetic resonance imaging (MRI). This approach, a combination of structural imaging of long-range fiber connections and functional imaging data, is illustrated in two distinct cognitive domains, visual attention and face perception. Structural imaging is performed with diffusion-weighted imaging (DWI) and fiber tractography, which track the diffusion of water molecules along white-matter fiber tracts in the brain (Figure 1). By visualizing these fiber tracts, we are able to investigate the long-range connective architecture of the brain. The results compare favorably with one of the most widely-used techniques in DWI, diffusion tensor imaging (DTI). DTI is unable to resolve complex configurations of fiber tracts, limiting its utility for constructing detailed, anatomically-informed models of brain function. In contrast, our analyses reproduce known neuroanatomy with precision and accuracy. This advantage is partly due to data acquisition procedures: while many DTI protocols measure diffusion in a small number of directions (e.g., 6 or 12), we employ a diffusion spectrum imaging (DSI)1, 2 protocol which assesses diffusion in 257 directions and at a range of magnetic gradient strengths. Moreover, DSI data allow us to use more sophisticated methods for reconstructing acquired data. In two experiments (visual attention and face perception), tractography reveals that co-active areas of the human brain are anatomically connected, supporting extant hypotheses that they form functional networks. DWI allows us to create a "circuit diagram" and reproduce it on an individual-subject basis, for

  10. Diffusion-Weighted MRI for Nodal Staging of Head and Neck Squamous Cell Carcinoma: Impact on Radiotherapy Planning

    SciTech Connect

    Dirix, Piet; Vandecaveye, Vincent; De Keyzer, Frederik; Op de beeck, Katya; Poorten, Vincent Vander; Delaere, Pierre; Verbeken, Eric; Hermans, Robert; Nuyts, Sandra

    2010-03-01

    Purpose: To evaluate the use of diffusion-weighted magnetic resonance imaging (DW-MRI) for nodal staging and its impact on radiotherapy (RT) planning. Methods and Materials: Twenty-two patients with locally advanced head and neck squamous cell carcinoma underwent contrast-enhanced computed tomography (CT), as well as MRI (with routine and DW sequences) prior to neck dissection. After topographic correlation, lymph nodes were evaluated microscopically with prekeratin immunostaining. Pathology results were correlated with imaging findings and an RT planning study was performed for these surgically treated patients. One set of target volumes was based on conventional imaging only, and another set was based on the corresponding DW-MRI images. A third reference set was contoured based solely on pathology results. Results: A sensitivity of 89% and a specificity of 97% per lymph node were found for DW-MRI. Nodal staging agreement between imaging and pathology was significantly stronger for DW-MRI (kappa = 0.97; 95% confidence interval [CI], 0.84-1.00) than for conventional imaging (kappa = 0.56; 95% CI, 0.16-0.96; p = 0.019, by McNemar's test). For both imaging modalities, the absolute differences between RT volumes and those obtained by pathology were calculated. Using an exact paired Wilcoxon test, the observed difference was significantly larger for conventional imaging than for DW-MRI for nodal gross tumor volume (p = 0.0013), as well as for nodal clinical target volume (p = 0.0415) delineation. Conclusions: These results suggest that DW-MRI is superior to conventional imaging for preradiotherapy nodal staging of head and neck squamous cell carcinoma, and provides a potential impact on organsparing and tumor control.

  11. Super-resolution reconstruction to increase the spatial resolution of diffusion weighted images from orthogonal anisotropic acquisitions.

    PubMed

    Scherrer, Benoit; Gholipour, Ali; Warfield, Simon K

    2012-10-01

    Diffusion-weighted imaging (DWI) enables non-invasive investigation and characterization of the white matter but suffers from a relatively poor spatial resolution. Increasing the spatial resolution in DWI is challenging with a single-shot EPI acquisition due to the decreased signal-to-noise ratio and T2(∗) relaxation effect amplified with increased echo time. In this work we propose a super-resolution reconstruction (SRR) technique based on the acquisition of multiple anisotropic orthogonal DWI scans. DWI scans acquired in different planes are not typically closely aligned due to the geometric distortion introduced by magnetic susceptibility differences in each phase-encoding direction. We compensate each scan for geometric distortion by acquisition of a dual echo gradient echo field map, providing an estimate of the field inhomogeneity. We address the problem of patient motion by aligning the volumes in both space and q-space. The SRR is formulated as a maximum a posteriori problem. It relies on a volume acquisition model which describes how the acquired scans are observations of an unknown high-resolution image which we aim to recover. Our model enables the introduction of image priors that exploit spatial homogeneity and enables regularized solutions. We detail our SRR optimization procedure and report experiments including numerical simulations, synthetic SRR and real world SRR. In particular, we demonstrate that combining distortion compensation and SRR provides better results than acquisition of a single isotropic scan for the same acquisition duration time. Importantly, SRR enables DWI with resolution beyond the scanner hardware limitations. This work provides the first evidence that SRR, which employs conventional single shot EPI techniques, enables resolution enhancement in DWI, and may dramatically impact the role of DWI in both neuroscience and clinical applications. PMID:22770597

  12. Longitudinal development in the preterm thalamus and posterior white matter: MRI correlations between diffusion weighted imaging and T2 relaxometry.

    PubMed

    Melbourne, Andrew; Eaton-Rosen, Zach; Orasanu, Eliza; Price, David; Bainbridge, Alan; Cardoso, M Jorge; Kendall, Giles S; Robertson, Nicola J; Marlow, Neil; Ourselin, Sebastien

    2016-07-01

    Infants born prematurely are at increased risk of adverse neurodevelopmental outcome. The measurement of white matter tissue composition and structure can help predict functional performance. Specifically, measurements of myelination and indicators of myelination status in the preterm brain could be predictive of later neurological outcome. Quantitative imaging of myelin could thus serve to develop biomarkers for prognosis or therapeutic intervention; however, accurate estimation of myelin content is difficult. This work combines diffusion MRI and multi-component T2 relaxation measurements in a group of 37 infants born very preterm and scanned between 27 and 58 weeks equivalent gestational age. Seven infants have longitudinal data at two time points that we analyze in detail. Our aim is to show that measurement of the myelin water fraction is achievable using widely available pulse sequences and state-of-the-art algorithmic modeling of the MR imaging procedure and that a multi-component fitting routine to multi-shell diffusion weighted data can show differences in neurite density and local spatial arrangement in grey and white matter. Inference on the myelin water fraction allows us to demonstrate that the change in diffusion properties of the preterm thalamus is not solely due to myelination (that increase in myelin content accounts for about a third of the observed changes) whilst the decrease in the posterior white matter T2 has no significant component that is due to myelin water content. This work applies multi-modal advanced quantitative neuroimaging to investigate changing tissue properties in the longitudinal setting. Hum Brain Mapp 37:2479-2492, 2016. © 2016 Wiley Periodicals, Inc. PMID:26996400

  13. Convergent connectivity and graded specialization in the rostral human temporal lobe as revealed by diffusion-weighted imaging probabilistic tractography.

    PubMed

    Binney, Richard J; Parker, Geoffrey J M; Lambon Ralph, Matthew A

    2012-10-01

    In recent years, multiple independent neuroscience investigations have implicated critical roles for the rostral temporal lobe in auditory and visual perception, language, and semantic memory. Although arising in the context of different cognitive functions, most of these suggest that there is a gradual convergence of sensory information in the temporal lobe that culminates in modality- and perceptually invariant representations at the most rostral aspect. Currently, however, too little is known regarding connectivity within the human temporal lobe to be sure of exactly how and where convergence occurs; existing hypotheses are primarily derived on the basis of cross-species generalizations from invasive nonhuman primate studies, the validity of which is unclear, especially where language function is concerned. In this study, we map the connectivity of the human rostral temporal lobe in vivo for the first time using diffusion-weighted imaging probabilistic tractography. The results indicate that convergence of sensory information in the temporal lobe is in fact a graded process that occurs along both its longitudinal and lateral axes and culminates in the most rostral limits. We highlight the consistency of our results with those of prior functional neuroimaging, computational modeling, and patient studies. By going beyond simple fasciculus reconstruction, we systematically explored the connectivity of specific temporal lobe areas to frontal and parietal language regions. In contrast to the graded within-temporal lobe connectivity, this intertemporal connectivity was found to dissociate across caudal, mid, and rostral subregions. Furthermore, we identified a basal rostral temporal region with very limited connectivity to areas outside the temporal lobe, which aligns with recent evidence that this subregion underpins the extraction of modality- and context-invariant semantic representations. PMID:22721379

  14. Detection of acute nervous system injury with advanced diffusion-weighted MRI: a simulation and sensitivity analysis.

    PubMed

    Skinner, Nathan P; Kurpad, Shekar N; Schmit, Brian D; Budde, Matthew D

    2015-11-01

    Diffusion-weighted imaging (DWI) is a powerful tool to investigate the microscopic structure of the central nervous system (CNS). Diffusion tensor imaging (DTI), a common model of the DWI signal, has a demonstrated sensitivity to detect microscopic changes as a result of injury or disease. However, DTI and other similar models have inherent limitations that reduce their specificity for certain pathological features, particularly in tissues with complex fiber arrangements. Methods such as double pulsed field gradient (dPFG) and q-vector magic angle spinning (qMAS) have been proposed to specifically probe the underlying microscopic anisotropy without interference from the macroscopic tissue organization. This is particularly important for the study of acute injury, where abrupt changes in the microscopic morphology of axons and dendrites manifest as focal enlargements known as beading. The purpose of this work was to assess the relative sensitivity of DWI measures to beading in the context of macroscopic fiber organization and edema. Computational simulations of DWI experiments in normal and beaded axons demonstrated that, although DWI models can be highly specific for the simulated pathologies of beading and volume fraction changes in coherent fiber pathways, their sensitivity to a single idealized pathology is considerably reduced in crossing and dispersed fibers. However, dPFG and qMAS have a high sensitivity for beading, even in complex fiber tracts. Moreover, in tissues with coherent arrangements, such as the spinal cord or nerve fibers in which tract orientation is known a priori, a specific dPFG sequence variant decreases the effects of edema and improves specificity for beading. Collectively, the simulation results demonstrate that advanced DWI methods, particularly those which sample diffusion along multiple directions within a single acquisition, have improved sensitivity to acute axonal injury over conventional DTI metrics and hold promise for more

  15. Longitudinal development in the preterm thalamus and posterior white matter: MRI correlations between diffusion weighted imaging and T2 relaxometry

    PubMed Central

    Eaton‐Rosen, Zach; Orasanu, Eliza; Price, David; Bainbridge, Alan; Cardoso, M. Jorge; Kendall, Giles S.; Robertson, Nicola J.; Marlow, Neil; Ourselin, Sebastien

    2016-01-01

    Abstract Infants born prematurely are at increased risk of adverse neurodevelopmental outcome. The measurement of white matter tissue composition and structure can help predict functional performance. Specifically, measurements of myelination and indicators of myelination status in the preterm brain could be predictive of later neurological outcome. Quantitative imaging of myelin could thus serve to develop biomarkers for prognosis or therapeutic intervention; however, accurate estimation of myelin content is difficult. This work combines diffusion MRI and multi‐component T2 relaxation measurements in a group of 37 infants born very preterm and scanned between 27 and 58 weeks equivalent gestational age. Seven infants have longitudinal data at two time points that we analyze in detail. Our aim is to show that measurement of the myelin water fraction is achievable using widely available pulse sequences and state‐of‐the‐art algorithmic modeling of the MR imaging procedure and that a multi‐component fitting routine to multi‐shell diffusion weighted data can show differences in neurite density and local spatial arrangement in grey and white matter. Inference on the myelin water fraction allows us to demonstrate that the change in diffusion properties of the preterm thalamus is not solely due to myelination (that increase in myelin content accounts for about a third of the observed changes) whilst the decrease in the posterior white matter T2 has no significant component that is due to myelin water content. This work applies multi‐modal advanced quantitative neuroimaging to investigate changing tissue properties in the longitudinal setting. Hum Brain Mapp 37:2479–2492, 2016. © The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.. PMID:26996400

  16. Application of 18F-FDG PET and diffusion weighted imaging (DWI) in multiple myeloma: comparison of functional imaging modalities

    PubMed Central

    Sachpekidis, Christos; Mosebach, Jennifer; Freitag, Martin T; Wilhelm, Thomas; Mai, Elias K; Goldschmidt, Hartmut; Haberkorn, Uwe; Schlemmer, Heinz-Peter; Delorme, Stefan; Dimitrakopoulou-Strauss, Antonia

    2015-01-01

    Aim of this prospective study was to assess the sensitivity of positron emission tomography (PET) and diffusion-weighted imaging (DWI) in detecting multiple myeloma (MM) lesions, using the well-established morphologic modalities magnetic resonance imaging (MRI) and computed tomography (CT) as the standard of reference (RS). The study included 24 MM patients (15 newly diagnosed, 9 pre-treated). All underwent 18F-FDG PET/CT and wholebody DWI. The findings in PET and DWI were compared to matching imaging findings in combined non-enhanced T1w, fat-saturated T2w (TIRM)- MRI, and low-dose CT. Patient-based analysis revealed that 15/24 patients (10 primary MM, 5 pre-treated) had myeloma lesions according to our RS. PET was positive in 13/24 patients (11 primary MM, 2 pre-treated) and DWI in 18/24 patients (12 primary MM, 6 pre-treated). Lesion-based analysis demonstrated 128 MM lesions, of which PET depicted 60/128 lesions (sensitivity 47%), while DWI depicted 99/128 lesions (sensitivity 77%). Further analysis including only the 15 untreated MM patients revealed a sensitivity of 90% for both PET and DWI and an overall concordance of PET and DWI of 72%. In conclusion, DWI was more sensitive than 18F-FDG PET in detecting myeloma lesions in a mixed population of primary and pre-treated MM patients. However, 18F-FDG PET and DWI demonstrated equivalent sensitivities in the sub-population of primary, untreated MM patients. This higher sensitivity of DWI in pre-treated patients may be due to the fact that 18F-FDG PET becomes negative earlier in the course of treatment in contrary to MRI, in which already treated lesions can remain visible. PMID:26550539

  17. Apparent diffusion coefficient evaluation for secondary changes in the cerebellum of rats after middle cerebral artery occlusion.

    PubMed

    Yang, Yunjun; Gao, Lingyun; Fu, Jun; Zhang, Jun; Li, Yuxin; Yin, Bo; Chen, Weijian; Geng, Daoying

    2013-11-01

    Supratentorial cerebral infarction can cause functional inhibition of remote regions such as the cerebellum, which may be relevant to diaschisis. This phenomenon is often analyzed using positron emission tomography and single photon emission CT. However, these methods are expensive and radioactive. Thus, the present study quantified the changes of infarction core and remote regions after unilateral middle cerebral artery occlusion using apparent diffusion coefficient values. Diffusion-weighted imaging showed that the area of infarction core gradually increased to involve the cerebral cortex with increasing infarction time. Diffusion weighted imaging signals were initially increased and then stabilized by 24 hours. With increasing infarction time, the apparent diffusion coefficient value in the infarction core and remote bilateral cerebellum both gradually decreased, and then slightly increased 3-24 hours after infarction. Apparent diffusion coefficient values at remote regions (cerebellum) varied along with the change of supratentorial infarction core, suggesting that the phenomenon of diaschisis existed at the remote regions. Thus, apparent diffusion coefficient values and diffusion weighted imaging can be used to detect early diaschisis. PMID:25206615

  18. Clinical Implications of Non-Steatotic Hepatic Fat Fractions on Quantitative Diffusion-Weighted Imaging of the Liver

    PubMed Central

    Dijkstra, Hildebrand; Handayani, Astri; Kappert, Peter; Oudkerk, Matthijs; Sijens, Paul E.

    2014-01-01

    Diffusion-weighted imaging (DWI) is an important diagnostic tool in the assessment of focal liver lesions and diffuse liver diseases such as cirrhosis and fibrosis. Quantitative DWI parameters such as molecular diffusion, microperfusion and their fractions, are known to be affected when hepatic fat fractions (HFF) are higher than 5.5% (steatosis). However, less is known about the effect on DWI for HFF in the normal non-steatotic range below 5.5%, which can be found in a large part of the population. The aim of this study was therefore to evaluate the diagnostic implications of non-steatotic HFF on quantitative DWI parameters in eight liver segments. For this purpose, eleven healthy volunteers (2 men, mean-age 31.0) were prospectively examined with DWI and three series of in-/out-of-phase dual-echo spoiled gradient-recalled MRI sequences to obtain the HFF and T2*. DWI data were analyzed using the intravoxel incoherent motion (IVIM) model. Four circular regions (ø22.3 mm) were drawn in each of eight liver segments and averaged. Measurements were divided in group 1 (HFF≤2.75%), group 2 (2.75< HFF ≤5.5%) and group 3 (HFF>5.5%). DWI parameters and T2* were compared between the three groups and between the segments. It was observed that the molecular diffusion (0.85, 0.72 and 0.49 ×10−3 mm2/s) and T2* (32.2, 27.2 and 21.0 ms) differed significantly between the three groups of increasing HFF (2.18, 3.50 and 19.91%). Microperfusion and its fraction remained similar for different HFF. Correlations with HFF were observed for the molecular diffusion (r = −0.514, p<0.001) and T2* (−0.714, p<0.001). Similar results were obtained for the majority of individual liver segments. It was concluded that fat significantly decreases molecular diffusion in the liver, also in absence of steatosis (HFF≤5.5%). Also, it was confirmed that fat influences T2*. Determination of HFF prior to quantitative DWI is therefore crucial. PMID:24505333

  19. Non-parametric representation and prediction of single- and multi-shell diffusion-weighted MRI data using Gaussian processes

    PubMed Central

    Andersson, Jesper L.R.; Sotiropoulos, Stamatios N.

    2015-01-01

    Diffusion MRI offers great potential in studying the human brain microstructure and connectivity. However, diffusion images are marred by technical problems, such as image distortions and spurious signal loss. Correcting for these problems is non-trivial and relies on having a mechanism that predicts what to expect. In this paper we describe a novel way to represent and make predictions about diffusion MRI data. It is based on a Gaussian process on one or several spheres similar to the Geostatistical method of “Kriging”. We present a choice of covariance function that allows us to accurately predict the signal even from voxels with complex fibre patterns. For multi-shell data (multiple non-zero b-values) the covariance function extends across the shells which means that data from one shell is used when making predictions for another shell. PMID:26236030

  20. Real-Time Correction of Rigid-Body-Motion-Induced Phase Errors for Diffusion-Weighted Steady State Free Precession Imaging

    PubMed Central

    O’Halloran, R; Aksoy, M; Aboussouan, E; Peterson, E; Van, A; Bammer, R

    2014-01-01

    Purpose Diffusion contrast in diffusion-weighted steady state free precession MRI is generated through the constructive addition of signal from many coherence pathways. Motion-induced phase causes destructive interference which results in loss of signal magnitude and diffusion contrast. In this work, a 3D navigator-based real-time correction of the rigid-body-motion-induced phase errors is developed for diffusion-weighted steady state free precession MRI. Methods The efficacy of the real-time prospective correction method in preserving phase coherence of the steady-state is tested in 3D phantom experiments and 3D scans of healthy human subjects. Results In nearly all experiments, the signal magnitude in images obtained with proposed prospective correction was higher than the signal magnitude in images obtained with no correction. In the human subjects the mean magnitude signal in the data was up to 30 percent higher with prospective motion correction than without. Prospective correction never resulted in a decrease in mean signal magnitude in either the data or in the images. Conclusions The proposed prospective motion correction method is shown to preserve the phase coherence of the steady state in diffusion-weighted steady state free precession MRI, thus mitigating signal magnitude losses that would confound the desired diffusion contrast. PMID:24715414

  1. The parallel-antiparallel signal difference in double-wave-vector diffusion-weighted MR at short mixing times: A phase evolution perspective

    NASA Astrophysics Data System (ADS)

    Finsterbusch, Jürgen

    2011-01-01

    Experiments with two diffusion weightings applied in direct succession in a single acquisition, so-called double- or two-wave-vector diffusion-weighting (DWV) experiments at short mixing times, have been shown to be a promising tool to estimate cell or compartment sizes, e.g. in living tissue. The basic theory for such experiments predicts that the signal decays for parallel and antiparallel wave vector orientations differ by a factor of three for small wave vectors. This seems to be surprising because in standard, single-wave-vector experiments the polarity of the diffusion weighting has no influence on the signal attenuation. Thus, the question how this difference can be understood more pictorially is often raised. In this rather educational manuscript, the phase evolution during a DWV experiment for simple geometries, e.g. diffusion between parallel, impermeable planes oriented perpendicular to the wave vectors, is considered step-by-step and demonstrates how the signal difference develops. Considering the populations of the phase distributions obtained, the factor of three between the signal decays which is predicted by the theory can be reproduced. Furthermore, the intermediate signal decay for orthogonal wave vector orientations can be derived when investigating diffusion in a box. Thus, the presented “phase gymnastics” approach may help to understand the signal modulation observed in DWV experiments at short mixing times.

  2. Spatial and Temporal Variation of b-Values in Southwest China

    NASA Astrophysics Data System (ADS)

    Zhang, Shenjian; Zhou, Shiyong

    2016-01-01

    In our study, we used an improved Bayesian method based on a basis spline (B-spline) function to estimate the spatial and temporal variations of b-values in Southwest China. We propose that b-values combined with seismicity and tectonic background can provide a fairly clear stress condition and can be used in earthquake hazard analysis. Very low b-values in Southwest China appear to be related to the 2008 M_s 8.0 Wenchuan earthquake. We also suggest that the decreasing b-value trend in the Longmen Shan area from 2000 to 2008 may be an indicator of the 2008 M_s 8.0 Wenchuan earthquake.

  3. Short-term probabilistic earthquake risk assessment considering time-dependent b values

    NASA Astrophysics Data System (ADS)

    Gulia, Laura; Tormann, Thessa; Wiemer, Stefan; Herrmann, Marcus; Seif, Stefanie

    2016-02-01

    Laboratory experiments highlight a systematic b value decrease during the stress increase period before failure, and some large natural events are known to show a precursory decrease in the b value. However, short-term forecast models currently consider only the generic probability that an event can trigger subsequent seismicity in the near field. While the probability increase over a stationary Poissonian background is substantial, selected case studies have shown through cost-benefit analysis that the absolute main shock probability remains too low to warrant significant mitigation actions. We analyze the probabilities considering both changes in the seismicity rates and temporal changes in the b value. The precursory b value decrease in the 2009 L'Aquila case results in an additional fiftyfold probability increase for a M6.3 event. Translated into time-varying hazard and risk, these changes surpass the cost-benefit threshold for short-term evacuation.

  4. Fractal distributions of stress and strength and variations of b-value

    NASA Technical Reports Server (NTRS)

    Huang, J.; Turcotte, D. L.

    1988-01-01

    A two-dimensional planar fault zone on which the difference between stress and strength follows a fractal distribution is simulated to study the variation of the frequency-magnitude b-value under different distributions of heterogeneities and ambient stress levels. It is suggested that earthquakes occur in regions where this difference exceeds a specified value and that the size of these regions is a measure of the magnitude of the associated earthquake. A systematic variation in b-value is observed. It is found that the b-value has a positive correlation with the fractal dimension of the distribution and is inversely related to the ambient stress level. Observational data are compared with the simulation, showing that the observed b-value variation before and during earthquake sequences is a result of changes in both the ambient stress level and in the fractal dimension of the stress-strength distribution.

  5. Detection and implication of significant temporal b-value variation during earthquake sequences

    NASA Astrophysics Data System (ADS)

    Gulia, Laura; Tormann, Thessa; Schorlemmer, Danijel; Wiemer, Stefan

    2016-04-01

    Earthquakes tend to cluster in space and time and periods of increased seismic activity are also periods of increased seismic hazard. Forecasting models currently used in statistical seismology and in Operational Earthquake Forecasting (e.g. ETAS) consider the spatial and temporal changes in the activity rates whilst the spatio-temporal changes in the earthquake size distribution, the b-value, are not included. Laboratory experiments on rock samples show an increasing relative proportion of larger events as the system approaches failure, and a sudden reversal of this trend after the main event. The increasing fraction of larger events during the stress increase period can be mathematically represented by a systematic b-value decrease, while the b-value increases immediately following the stress release. We investigate whether these lab-scale observations also apply to natural earthquake sequences and can help to improve our understanding of the physical processes generating damaging earthquakes. A number of large events nucleated in low b-value regions and spatial b-value variations have been extensively documented in the past. Detecting temporal b-value evolution with confidence is more difficult, one reason being the very different scales that have been suggested for a precursory drop in b-value, from a few days to decadal scale gradients. We demonstrate with the results of detailed case studies of the 2009 M6.3 L'Aquila and 2011 M9 Tohoku earthquakes that significant and meaningful temporal b-value variability can be detected throughout the sequences, which e.g. suggests that foreshock probabilities are not generic but subject to significant spatio-temporal variability. Such potential conclusions require and motivate the systematic study of many sequences to investigate whether general patterns exist that might eventually be useful for time-dependent or even real-time seismic hazard assessment.

  6. Earthquake Apparent Stress Scaling

    NASA Astrophysics Data System (ADS)

    Walter, W. R.; Mayeda, K.; Ruppert, S.

    2002-12-01

    There is currently a disagreement within the geophysical community on the way earthquake energy scales with magnitude. One set of recent papers finds evidence that energy release per seismic moment (apparent stress) is constant (e.g. Choy and Boatwright, 1995; McGarr, 1999; Ide and Beroza, 2001). Another set of recent papers finds the apparent stress increases with magnitude (e.g. Kanamori et al., 1993 Abercrombie, 1995; Mayeda and Walter, 1996; Izutani and Kanamori, 2001). The resolution of this issue is complicated by the difficulty of accurately accounting for and determining the seismic energy radiated by earthquakes over a wide range of event sizes in a consistent manner. We have just started a project to reexamine this issue by analyzing aftershock sequences in the Western U.S. and Turkey using two different techniques. First we examine the observed regional S-wave spectra by fitting with a parametric model (Walter and Taylor, 2002) with and without variable stress drop scaling. Because the aftershock sequences have common stations and paths we can examine the S-wave spectra of events by size to determine what type of apparent stress scaling, if any, is most consistent with the data. Second we use regional coda envelope techniques (e.g. Mayeda and Walter, 1996; Mayeda et al, 2002) on the same events to directly measure energy and moment. The coda techniques corrects for path and site effects using an empirical Green function technique and independent calibration with surface wave derived moments. Our hope is that by carefully analyzing a very large number of events in a consistent manner using two different techniques we can start to resolve this apparent stress scaling issue. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

  7. The Role of 3 Tesla Diffusion-Weighted Imaging in the Differential Diagnosis of Benign versus Malignant Cervical Lymph Nodes in Patients with Head and Neck Squamous Cell Carcinoma

    PubMed Central

    Pranno, Nicola; Sartori, Alessandro; Gigli, Silvia; Lo Mele, Luigi; Marsella, Luigi Tonino

    2014-01-01

    Objective. The aim of this study was to validate the role of diffusion-weighted imaging (DWI) at 3 Tesla in the differential diagnosis between benign and malignant laterocervical lymph nodes in patients with head and neck squamous cell carcinoma (HNSCC). Materials and Methods. Before undergoing surgery, 80 patients, with biopsy proven HNSCC, underwent a magnetic resonance exam. Sensitivity (Se) and specificity (Spe) of conventional criteria and DWI in detecting laterocervical lymph node metastases were calculated. Histological results from neck dissection were used as standard of reference. Results. In the 239 histologically proven metastatic lymphadenopathies, the mean apparent diffusion coefficient (ADC) value was 0.903 × 10−3 mm2/sec. In the 412 pathologically confirmed benign lymph nodes, an average ADC value of 1.650 × 10−3 mm2/sec was found. For differentiating between benign versus metastatic lymph nodes, DWI showed Se of 97% and Spe of 93%, whereas morphological criteria displayed Se of 61% and Spe of 98%. DWI showed an area under the ROC curve (AUC) of 0.964, while morphological criteria displayed an AUC of 0.715. Conclusions. In a DWI negative neck for malignant lymph nodes, the planned dissection could be converted to a wait-and-scan policy, whereas DWI positive neck would support the decision to perform a neck dissection. PMID:25003115

  8. Seismic b-Values, Bouguer Gravity and Heat Flow Data Beneath Eastern Anatolia, Turkey: Tectonic Implications

    NASA Astrophysics Data System (ADS)

    Maden, Nafiz; Öztürk, Serkan

    2015-07-01

    In this paper, we analyze the relationships between the seismic b-values, Bouguer gravity and heat flow data in the Eastern Anatolia region of Turkey. For this purpose, spatial distributions of b-value, Bouguer gravity and heat flow have been presented for different depths and locations. In distinction to previous studies which have used only two parameters (gravity and seismic b-value or heat flow and seismic b-value), we have combined seismic b-values, Bouguer gravity and heat flow data to determine the new results on the active tectonics of the Eastern Anatolia region. Our analysis shows that there are significant and robust correlations amidst the heat flow data, Bouguer gravity anomaly and seismic b-values. The crustal structure is thick in areas where the large negative gravity anomalies and low b-values are observed. On the contrary, the regions with positive gravity anomalies and high b-values are likely to be associated with magma chambers or crustal low-velocity zones. We also provide some evidence suggesting that high b-values and high heat flow values can be related to the magmatic activities beneath the volcanic chain in the Eastern Pontide orogenic belt. Consequently, we have reached some conclusions for the Eastern Anatolia region: (1) The Moho to surface is rather thick and earthquakes are relatively smaller beneath the volcanic chain where the high heat flow values are observed, (2) a southward subduction model could have existed for the development of the Pontides during the late Mesozoic-Cenozoic era, (3) hot and unstable mantle lid zones or a lithosphere deprived of mantle under the study region is much more plausible, (4) a southward movement of the subduction plate and a northward extension of the Black Sea increase the state of stress along the trench axis and decrease the b-value, and (5) these movements may load the stress energy to the fault zones, thereby causing the catastrophic earthquakes in the Eastern Anatolia region.

  9. Cervical Gross Tumor Volume Dose Predicts Local Control Using Magnetic Resonance Imaging/Diffusion-Weighted Imaging—Guided High-Dose-Rate and Positron Emission Tomography/Computed Tomography—Guided Intensity Modulated Radiation Therapy

    SciTech Connect

    Dyk, Pawel; Jiang, Naomi; Sun, Baozhou; DeWees, Todd A.; Fowler, Kathryn J.; Narra, Vamsi; Garcia-Ramirez, Jose L.; Schwarz, Julie K.; Grigsby, Perry W.

    2014-11-15

    Purpose: Magnetic resonance imaging/diffusion weighted-imaging (MRI/DWI)-guided high-dose-rate (HDR) brachytherapy and {sup 18}F-fluorodeoxyglucose (FDG) — positron emission tomography/computed tomography (PET/CT)-guided intensity modulated radiation therapy (IMRT) for the definitive treatment of cervical cancer is a novel treatment technique. The purpose of this study was to report our analysis of dose-volume parameters predicting gross tumor volume (GTV) control. Methods and Materials: We analyzed the records of 134 patients with International Federation of Gynecology and Obstetrics stages IB1-IVB cervical cancer treated with combined MRI-guided HDR and IMRT from July 2009 to July 2011. IMRT was targeted to the metabolic tumor volume and lymph nodes by use of FDG-PET/CT simulation. The GTV for each HDR fraction was delineated by use of T2-weighted or apparent diffusion coefficient maps from diffusion-weighted sequences. The D100, D90, and Dmean delivered to the GTV from HDR and IMRT were summed to EQD2. Results: One hundred twenty-five patients received all irradiation treatment as planned, and 9 did not complete treatment. All 134 patients are included in this analysis. Treatment failure in the cervix occurred in 24 patients (18.0%). Patients with cervix failures had a lower D100, D90, and Dmean than those who did not experience failure in the cervix. The respective doses to the GTV were 41, 58, and 136 Gy for failures compared with 67, 99, and 236 Gy for those who did not experience failure (P<.001). Probit analysis estimated the minimum D100, D90, and Dmean doses required for ≥90% local control to be 69, 98, and 260 Gy (P<.001). Conclusions: Total dose delivered to the GTV from combined MRI-guided HDR and PET/CT-guided IMRT is highly correlated with local tumor control. The findings can be directly applied in the clinic for dose adaptation to maximize local control.

  10. Are volcanic seismic b-values high, and if so when?

    NASA Astrophysics Data System (ADS)

    Roberts, Nick S.; Bell, Andrew F.; Main, Ian G.

    2015-12-01

    The Gutenberg-Richter exponent b is a measure of the relative proportion of large and small earthquakes. It is commonly used to infer material properties such as heterogeneity, or mechanical properties such as the state of stress from earthquake populations. It is 'well known' that the b-value tends to be high or very high for volcanic earthquake populations relative to b = 1 for those of tectonic earthquakes, and that b varies significantly with time during periods of unrest. We first review the supporting evidence from 34 case studies, and identify weaknesses in this argument due predominantly to small sample size, the narrow bandwidth of magnitude scales available, variability in the methods used to assess the minimum or cutoff magnitude Mc, and to infer b. Informed by this, we use synthetic realisations to quantify the effect of choice of the cutoff magnitude on maximum likelihood estimates of b, and suggest a new work flow for this choice. We present the first quantitative estimate of the error in b introduced by uncertainties in estimating Mc, as a function of the number of events and the b-value itself. This error can significantly exceed the commonly-quoted statistical error in the estimated b-value, especially for the case that the underlying b-value is high. We apply the new methods to data sets from recent periods of unrest in El Hierro and Mount Etna. For El Hierro we confirm significantly high b-values of 1.5-2.5 prior to the 10 October 2011 eruption. For Mount Etna the b-values are indistinguishable from b = 1 within error, except during the flank eruptions at Mount Etna in 2001-2003, when 1.5 < b < 2.0. For the time period analysed, they are rarely lower than b = 1. Our results confirm that these volcano-tectonic earthquake populations can have systematically high b-values, especially when associated with eruptions. At other times they can be indistinguishable from those of tectonic earthquakes within the total error. The results have significant

  11. Apparent arterial compliance.

    PubMed

    Quick, C M; Berger, D S; Noordergraaf, A

    1998-04-01

    Recently, there has been renewed interest in estimating total arterial compliance. Because it cannot be measured directly, a lumped model is usually applied to derive compliance from aortic pressure and flow. The archetypical model, the classical two-element windkessel, assumes 1) system linearity and 2) infinite pulse wave velocity. To generalize this model, investigators have added more elements and have incorporated nonlinearities. A different approach is taken here. It is assumed that the arterial system 1) is linear and 2) has finite pulse wave velocity. In doing so, the windkessel is generalized by describing compliance as a complex function of frequency that relates input pressure to volume stored. By applying transmission theory, this relationship is shown to be a function of heart rate, peripheral resistance, and pulse wave reflection. Because this pressure-volume relationship is generally not equal to total arterial compliance, it is termed "apparent compliance." This new concept forms the natural counterpart to the established concept of apparent pulse wave velocity. PMID:9575945

  12. The apparent Universe

    NASA Astrophysics Data System (ADS)

    Binétruy, P.; Helou, A.

    2015-10-01

    We exploit the parallel between dynamical black holes and cosmological spacetimes to describe the evolution of Friedmann-Lemaître-Robertson-Walker universes from the point of view of an observer in terms of the dynamics of the apparent horizon. Using the Hayward-Kodama formalism of dynamical black holes, we clarify the role of the Clausius relation to derive the Friedmann equations for a Universe, in the spirit of Jacobson’s work on the thermodynamics of spacetime. We also show how dynamics at the horizon naturally leads to the quantum-mechanical process of Hawking radiation. We comment on the connection of this work with recent ideas to consider our observable Universe as a Bose-Einstein condensate and on the corresponding role of vacuum energy.

  13. Boosted apparent horizons

    NASA Astrophysics Data System (ADS)

    Akcay, Sarp

    Boosted black holes play an important role in General Relativity (GR), especially in relation to the binary black hole problem. Solving Einstein vac- uum equations in the strong field regime had long been the holy grail of numerical relativity until the significant breakthroughs made in 2005 and 2006. Numerical relativity plays a crucial role in gravitational wave detection by providing numerically generated gravitational waveforms that help search for actual signatures of gravitational radiation exciting laser interferometric de- tectors such as LIGO, VIRGO and GEO600 here on Earth. Binary black holes orbit each other in an ever tightening adiabatic inspiral caused by energy loss due to gravitational radiation emission. As the orbits shrinks, the holes speed up and eventually move at relativistic speeds in the vicinity of each other (separated by ~ 10M or so where 2M is the Schwarzschild radius). As such, one must abandon the Newtonian notion of a point mass on a circular orbit with tangential velocity and replace it with the concept of black holes, cloaked behind spheroidal event horizons that become distorted due to strong gravity, and further appear distorted because of Lorentz effects from the high orbital velocity. Apparent horizons (AHs) are 2-dimensional boundaries that are trapped surfaces. Conceptually, one can think of them as 'quasi-local' definitions for a black hole horizon. This will be explained in more detail in chapter 2. Apparent horizons are especially important in numerical relativity as they provide a computationally efficient way of describing and locating a black hole horizon. For a stationary spacetime, apparent horizons are 2-dimensional cross-sections of the event horizon, which is itself a 3-dimensional null surface in spacetime. Because an AH is a 2-dimensional cross-section of an event horizon, its area remains invariant under distortions due to Lorentz boosts although its shape changes. This fascinating property of the AH can be

  14. Apparent capitellar fractures.

    PubMed

    Ring, David

    2007-11-01

    Isolated capitellar fractures are rare but are identified as such, even when they are more complex, because the displaced capitellar fracture is usually the most obvious and identifiable radiographic finding and because teaching has traditionally underemphasized the involvement of the trochlea in such fractures. The author prefers the term 'apparent capitellar fractures' and draws on his experience to explain why he favors three-dimensional CT for depicting fracture detail. This article discusses treatment options, emphasizing open reduction and internal fixation to restore the native elbow. Operative techniques, including extensile lateral exposure and olecranon osteotomy; fixation techniques; and elbow arthroplasty, are described. Complications, such as ulnar neuropathy and infection, are also covered. PMID:18054674

  15. Earthquake Apparent Stress Scaling

    NASA Astrophysics Data System (ADS)

    Mayeda, K.; Walter, W. R.

    2003-04-01

    There is currently a disagreement within the geophysical community on the way earthquake energy scales with magnitude. One set of recent papers finds evidence that energy release per seismic moment (apparent stress) is constant (e.g. Choy and Boatwright, 1995; McGarr, 1999; Ide and Beroza, 2001). Another set of recent papers finds the apparent stress increases with magnitude (e.g. Kanamori et al., 1993 Abercrombie, 1995; Mayeda and Walter, 1996; Izutani and Kanamori, 2001). The resolution of this issue is complicated by the difficulty of accurately accounting for and determining the seismic energy radiated by earthquakes over a wide range of event sizes in a consistent manner. We have just started a project to reexamine this issue by applying the same methodology to a series of datasets that spans roughly 10 orders in seismic moment, M0. We will summarize recent results using a coda envelope methodology of Mayeda et al, (2003) which provide the most stable source spectral estimates to date. This methodology eliminates the complicating effects of lateral path heterogeneity, source radiation pattern, directivity, and site response (e.g., amplification, f-max and kappa). We find that in tectonically active continental crustal areas the total radiated energy scales as M00.25 whereas in regions of relatively younger oceanic crust, the stress drop is generally lower and exhibits a 1-to-1 scaling with moment. In addition to answering a fundamental question in earthquake source dynamics, this study addresses how one would scale small earthquakes in a particular region up to a future, more damaging earthquake. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

  16. Testing the reliability of the Gutenberg-Richter b-value to aid volcanic eruption forecasting

    NASA Astrophysics Data System (ADS)

    Roberts, Nick; Bell, Andrew; Main, Ian

    2014-05-01

    The distribution of earthquake magnitudes is an important additional attribute of a volcanic earthquake catalogue and analyses of properties of the "frequency-magnitude distribution" (FMD) underpins most studies of volcanic seismicity. The event rate and inter-event intervals are of primary interest as their changes can be a primary indicator of volcanic unrest. The classic model for the earthquake FMD is the Gutenberg-Richter (GR) relation (Gutenberg and Richter, 1954): log(N) = a - bM, where N is the cumulative number of earthquakes of magnitude equal to or greater than M, a is a measure of the total seismicity rate of the region and the b-value represents the relative proportion of large and small events in the catalogue. The b-value for tectonic earthquakes has been well studied with a global average of approximately 1. However, b-values in volcanic settings are often reported to be much higher, sometimes with values as high as 3. Spatial variations in the volcanic b-value have been used to map stress conditions and magma reservoirs, and it has been argued that temporal variations have the potential to forecast eruptive activity. Here we assess different methodologies for analysing properties of the FMD, and re-evaluate what we know about the FMD of volcanic earthquakes. Using synthetic models we evaluate the reliability of methods for calculating the catalogue completeness magnitude where earthquake rates fluctuate rapidly in time to simulate pre-, syn- and post- earthquake swarm activity. We also evaluate to what extent volcanic FMDs are consistent with the GR model, using earthquake data from volcanoes including El Hierro, Canary Islands and Kilauea and Mauna Loa, Hawaii. We suggest that much of the proposed variation in b-value can be attributed to uncertainty in the completeness magnitude, and FMDs not displaying GR properties. In the case where event rate is pulsing or swarming the b-value has a tendency not to stabilise with increasing completeness

  17. Reduced Field-of-View Diffusion-Weighted Magnetic Resonance Imaging of the Pancreas: Comparison with Conventional Single-Shot Echo-Planar Imaging

    PubMed Central

    Kim, Hyungjin; Yoon, Jeong Hee; Jang, Jin-Young; Kim, Sun-Whe; Ryu, Ji Kon; Kannengiesser, Stephan; Han, Joon Koo; Choi, Byung Ihn

    2015-01-01

    Objective To investigate the image quality (IQ) and apparent diffusion coefficient (ADC) of reduced field-of-view (FOV) di-ffusion-weighted imaging (DWI) of pancreas in comparison with full FOV DWI. Materials and Methods In this retrospective study, 2 readers independently performed qualitative analysis of full FOV DWI (FOV, 38 × 38 cm; b-value, 0 and 500 s/mm2) and reduced FOV DWI (FOV, 28 × 8.5 cm; b-value, 0 and 400 s/mm2). Both procedures were conducted with a two-dimensional spatially selective radiofrequency excitation pulse, in 102 patients with benign or malignant pancreatic diseases (mean size, 27.5 ± 14.4 mm). The study parameters included 1) anatomic structure visualization, 2) lesion conspicuity, 3) artifacts, 4) IQ score, and 5) subjective clinical utility for confirming or excluding initially considered differential diagnosis on conventional imaging. Another reader performed quantitative ADC measurements of focal pancreatic lesions and parenchyma. Wilcoxon signed-rank test was used to compare qualitative scores and ADCs between DWI sequences. Mann Whitney U-test was used to compare ADCs between the lesions and parenchyma. Results On qualitative analysis, reduced FOV DWI showed better anatomic structure visualization (2.76 ± 0.79 at b = 0 s/mm2 and 2.81 ± 0.64 at b = 400 s/mm2), lesion conspicuity (3.11 ± 0.99 at b = 0 s/mm2 and 3.15 ± 0.79 at b = 400 s/mm2), IQ score (8.51 ± 2.05 at b = 0 s/mm2 and 8.79 ± 1.60 at b = 400 s/mm2), and higher clinical utility (3.41 ± 0.64), as compared to full FOV DWI (anatomic structure, 2.18 ± 0.59 at b = 0 s/mm2 and 2.56 ± 0.47 at b = 500 s/mm2; lesion conspicuity, 2.55 ± 1.07 at b = 0 s/mm2 and 2.89 ± 0.86 at b = 500 s/mm2; IQ score, 7.13 ± 1.83 at b = 0 s/mm2 and 8.17 ± 1.31 at b = 500 s/mm2; clinical utility, 3.14 ± 0.70) (p < 0.05). Artifacts were significantly improved on reduced FOV DWI (2.65 ± 0.68) at b = 0 s/mm2 (full FOV DWI, 2.41 ± 0.63) (p < 0.001). On quantitative analysis, there were

  18. Gutenberg-Richter b-value maximum likelihood estimation and sample size

    NASA Astrophysics Data System (ADS)

    Nava, F. A.; Márquez-Ramírez, V. H.; Zúñiga, F. R.; Ávila-Barrientos, L.; Quinteros, C. B.

    2016-06-01

    The Aki-Utsu maximum likelihood method is widely used for estimation of the Gutenberg-Richter b-value, but not all authors are conscious of the method's limitations and implicit requirements. The Aki/Utsu method requires a representative estimate of the population mean magnitude; a requirement seldom satisfied in b-value studies, particularly in those that use data from small geographic and/or time windows, such as b-mapping and b-vs-time studies. Monte Carlo simulation methods are used to determine how large a sample is necessary to achieve representativity, particularly for rounded magnitudes. The size of a representative sample weakly depends on the actual b-value. It is shown that, for commonly used precisions, small samples give meaningless estimations of b. Our results give estimates on the probabilities of getting correct estimates of b for a given desired precision for samples of different sizes. We submit that all published studies reporting b-value estimations should include information about the size of the samples used.

  19. Quantifying the effect of tissue deformation on diffusion-weighted MRI: a mathematical model and an efficient simulation framework applied to cardiac diffusion imaging.

    PubMed

    Mekkaoui, Imen; Moulin, Kevin; Croisille, Pierre; Pousin, Jerome; Viallon, Magalie

    2016-08-01

    Cardiac motion presents a major challenge in diffusion weighted MRI, often leading to large signal losses that necessitate repeated measurements. The diffusion process in the myocardium is difficult to investigate because of the unqualified sensitivity of diffusion measurements to cardiac motion. A rigorous mathematical formalism is introduced to quantify the effect of tissue motion in diffusion imaging. The presented mathematical model, based on the Bloch-Torrey equations, takes into account deformations according to the laws of continuum mechanics. Approximating this mathematical model by using finite elements method, numerical simulations can predict the sensitivity of the diffusion signal to cardiac motion. Different diffusion encoding schemes are considered and the diffusion weighted MR signals, computed numerically, are compared to available results in literature. Our numerical model can identify the existence of two time points in the cardiac cycle, at which the diffusion is unaffected by myocardial strain and cardiac motion. Of course, these time points depend on the type of diffusion encoding scheme. Our numerical results also show that the motion sensitivity of the diffusion sequence can be reduced by using either spin echo technique with acceleration motion compensation diffusion gradients or stimulated echo acquisition mode with unipolar and bipolar diffusion gradients. PMID:27385441

  20. Quantifying the effect of tissue deformation on diffusion-weighted MRI: a mathematical model and an efficient simulation framework applied to cardiac diffusion imaging

    NASA Astrophysics Data System (ADS)

    Mekkaoui, Imen; Moulin, Kevin; Croisille, Pierre; Pousin, Jerome; Viallon, Magalie

    2016-08-01

    Cardiac motion presents a major challenge in diffusion weighted MRI, often leading to large signal losses that necessitate repeated measurements. The diffusion process in the myocardium is difficult to investigate because of the unqualified sensitivity of diffusion measurements to cardiac motion. A rigorous mathematical formalism is introduced to quantify the effect of tissue motion in diffusion imaging. The presented mathematical model, based on the Bloch–Torrey equations, takes into account deformations according to the laws of continuum mechanics. Approximating this mathematical model by using finite elements method, numerical simulations can predict the sensitivity of the diffusion signal to cardiac motion. Different diffusion encoding schemes are considered and the diffusion weighted MR signals, computed numerically, are compared to available results in literature. Our numerical model can identify the existence of two time points in the cardiac cycle, at which the diffusion is unaffected by myocardial strain and cardiac motion. Of course, these time points depend on the type of diffusion encoding scheme. Our numerical results also show that the motion sensitivity of the diffusion sequence can be reduced by using either spin echo technique with acceleration motion compensation diffusion gradients or stimulated echo acquisition mode with unipolar and bipolar diffusion gradients.

  1. Earthquake swarm and b-value characterization of the Yellowstone volcano-tectonic system

    NASA Astrophysics Data System (ADS)

    Farrell, Jamie; Husen, Stephan; Smith, Robert B.

    2009-11-01

    The Yellowstone volcanic field, Yellowstone National Park, is one of the most seismically active areas of the western U.S., experiencing the deadly 1959 M7.5 Hebgen Lake, MT, earthquake adjacent to the 0.64-Ma caldera, as well as more than 30,000 earthquakes from 1973 to 2007. This well-recorded seismic activity offers the opportunity to study the temporal and spatial occurrence of earthquakes and extensive earthquake swarms and how they relate to active volcanic and tectonic processes. We characterize the distribution of earthquakes by analyzing the rate of occurrence characterized by the b-value. To accurately determine b-values, the earthquake catalog was filtered to identify statistically time- and spatially-dependent related events, defined as swarms, from independent single main and aftershocks. An algorithm was employed that identified 69 swarms for 1984-2006 based on inter-event times and spatial clustering. The swarms varied in duration from 1 to 46 days with the number of events varying from 30 to 722 with magnitudes of - 1.2 to 4.8. All of the swarm events as well as the 597 events triggered by the 2002 Denali fault, AK, earthquake were removed from the catalog for analysis. The catalog data were then filtered for a magnitude of completeness ( MCOMP) of 1.5 and the b-value distribution for the Yellowstone region was determined with the de-swarmed data. b-values ranged from 0.6 ± 0.1 to 1.5 ± 0.05 with the highest values associated with the youthful 150,000-year old Mallard Lake resurgent dome. These variations are interpreted to be related to variations in stresses accompanying the migration of magmatic and hydrothermal fluids. An area of high b-values (up to 1.3 ± 0.1) associated with the Hebgen Lake fault zone west of the Yellowstone caldera could be related to the transport of magmatic fluids out of the Yellowstone volcanic system or could be indicative of a relative low stress regime resulting from the stress release by the Hebgen Lake earthquake

  2. Spatio-temporal variations of b-value in and around north Pakistan

    NASA Astrophysics Data System (ADS)

    Rehman, Khaista; Ali, Asghar; Ahmed, Sajjad; Ali, Wajid; Ali, Aamir; Khan, Muhammad Younis

    2015-10-01

    The seismotectonic structure of north Pakistan has been formed by ongoing collision between the Eurasian and Indian plates. North Pakistan and the adjoining areas experienced many large earthquakes in the past, which resulted in considerable damages and loss of life. A magnitude-homogenous earthquake catalogue for north Pakistan and its surrounding areas for the instrumental period from 1964 to 2007 is used for analysis. We presented seismicity picture of the Hindukush-Pamir-Karakoram (HPK), Kohistan Island Arc (KIA) and Hazara-Kashmir-Himalayas (HKH) using various histograms and time series plots of the dataset. The b-value for each accreted domain is derived separately and investigated through a process of mutual correlation. Our computed temporal variation of b-value in Hazara region shows a significant decrease prior to 2005 Kashmir earthquake.

  3. Serum lipids and apolipoprotein B values, blood pressure and pulse rate in anorexia nervosa.

    PubMed

    Sánchez-Muniz, F J; Marcos, A; Varela, P

    1991-01-01

    Some risk factors associated with coronary heart disease (CHD) were evaluated in patients with different types of anorexia nervosa (AN). Anthropometric parameters, serum cholesterol, triglycerides and apoprotein (apo) B values, blood pressure and pulse rate were tested in 29 young female patients and 16 controls. Cholesterol, triglycerides and apo B were higher at the acute period of the illness (AN1), whereas at the chronic period the values of these parameters tended to normalize. Triglycerides were higher in patients who binge ate (bulimarexia). Systolic blood pressure decreased in all types of AN, while diastolic blood pressure decreased only in AN1; pulse rate was not altered. According to cholesterol and apo B values, AN patients may be at risk of CHD if they remain at low body weight. PMID:1855497

  4. Short-term earthquake risk assessment considering time-dependent b-values

    NASA Astrophysics Data System (ADS)

    Gulia, Laura; Tormann, Thessa; Wiemer, Stefan

    2015-04-01

    Observations from laboratory experiments measuring acoustic emissions during loading cycles in pressurized rock samples have repeatedly suggested that small events in the precursory phase of an impending large event change in their relative size distribution. In particular, they highlight a systematic b-value decrease during the stress increase period before the main event. A number of large natural events, but not all of them, have been shown to have a precursory decrease in the b-value at very different time scales, from months to a few days before the subsequent mainshock. At present short term-forecast models such as STEP and ETAS consider the generic probability that an event can trigger subsequent seismicity in the near field; the rate increasing during the foreshock sequences can offer a probability gain for a significant earthquake to happen. While the probability gain of a stationary Poissonian background is substantial, selected case studies have shown through cost-benefit analysis that the absolute probability remains too low to warrant actions. This was shown for example by van Stiphout et al. (2010, GRL), for the 2009 a Mw 6.3 earthquake that hit the city of L'Aquila (Central Italy) after three months of foreshock activity. We here analyze the probability gain of a novel generation of short term forecast models which considers both the change in the seismicity rates and the temporal changes in the b-value. Changes in earthquake probability are then translated also into time-dependent hazard and risk. Preliminary results suggest that the precursory b-value decrease in the L'Aquila case results in an additional probability increase of a M6.3 event of about a factor of 30-50, which then surpasses the cost-benefit threshold for short-term evacuation in selected cases.

  5. Tectonic implications of spatial variation of b-values and heat flow in the Aegean region

    NASA Astrophysics Data System (ADS)

    Kalyoncuoglu, U. Yalcin; Elitok, Ömer; Dolmaz, M. Nuri

    2013-03-01

    The Aegean region is tectonically a complex area characterized mainly by the subduction of African oceanic lithosphere beneath the Aegean continental lithosphere including extensional subbasins and mantle driven block rotations. In this study, spatial distribution of earthquakes, b-value distribution, and heat flow data have been analyzed to reveal the deep structural features of the Aegean region. b-value distributions show two low NE-SW and NW-SE trending b-anomaly zones in the western and eastern side of the Crete, implying slab tear within the Aegean slab. Earthquake foci distribution indicates that the Aegean slab steepens in the eastern side of the Crete, compared to its western side. Earthquake foci reach maximum depth of 180 km along the Cycladic arc axis, suggesting northward subducted slab geometry. The low seismic activities and high b-value anomalies within Aegean basin, except North Aegean Trough, can be compared to higher heat flow. We concluded that collision-induced westward mantle flow beneath Turkey followed by hard collision between Arabian-Eurasian continental plates played a major role in the evolution of clockwise rotational retreat of the Aegean slab and slab steepening to the east of the Crete.

  6. Variability of the b value in the Gutenberg-Richter distribution

    NASA Astrophysics Data System (ADS)

    Godano, C.; Lippiello, E.; de Arcangelis, L.

    2014-12-01

    The b value of the Gutenberg-Richter (GR) distribution is estimated as a function of a threshold magnitude mth and it is found to depend on mth for magnitudes larger than the completeness magnitude mc. We identify a magnitude interval [mc, mm] where b is a decreasing function of mth followed by a regime of increasing b for large magnitudes. This is a common feature of experimental catalogues for different geographic areas. The increase at large mth is explained in terms of an upper magnitude cut-off in experimental catalogues due to finite size effects. We develop a rigorous mathematical framework to relate the decrease of b in the intermediate regime to the functional form of the distribution of the b values. We propose two hypotheses: The first is that the spatial and temporal variability of b leads to a b distribution peaked around its average value. The second is that main shocks and aftershocks are distributed according to the GR law with different b values, leading to a bimodal distribution of b. Simulated Epidemic Type Aftershock Sequences catalogues, generated according to this hypothesis, exhibit the same magnitude distribution of experimental ones. In alternative, we cannot exclude the b dependence on m caused by magnitudes not homogeneously evaluated in a seismic catalogue. In the latter scenario our results provide the correction terms to the estimated magnitudes.

  7. A Spin Echo Sequence with a Single-Sided Bipolar Diffusion Gradient Pulse to Obtain Snapshot Diffusion Weighted Images in Moving Media

    PubMed Central

    Freidlin, R. Z.; Kakareka, J. W.; Pohida, T. J.; Komlosh, M. E.; Basser, P. J.

    2013-01-01

    In vivo MRI data can be corrupted by motion. Motion artifacts are particularly troublesome in Diffusion Weighted MRI (DWI), since the MR signal attenuation due to Brownian motion can be much less than the signal loss due to dephasing from other types of complex tissue motion, which can significantly degrade the estimation of self-diffusion coefficients, diffusion tensors, etc. This paper describes a snapshot DWI sequence, which utilizes a novel single-sided bipolar diffusion sensitizing gradient pulse within a spin echo sequence. The proposed method shortens the diffusion time by applying a single refocused bipolar diffusion gradient on one side of a refocusing RF pulse, instead of a set of diffusion sensitizing gradients, separated by a refocusing RF pulse, while reducing the impact of magnetic field inhomogeneity by using a spin echo sequence. A novel MRI phantom that can exhibit a range of complex motions was designed to demonstrate the robustness of the proposed DWI sequence. PMID:22743539

  8. Role of Diffusion-weighted Imaging in Acute Stroke Management using Low-field Magnetic Resonance Imaging in Resource-limited Settings

    PubMed Central

    Okorie, Chinonye K; Ogbole, Godwin I; Owolabi, Mayowa O; Ogun, Olufunmilola; Adeyinka, Abiodun; Ogunniyi, Adesola

    2015-01-01

    A variety of imaging modalities exist for the diagnosis of stroke. Several studies have been carried out to ascertain their contribution to the management of acute stroke and to compare the benefits and limitations of each modality. Diffusion-weighted imaging (DWI) has been described as the optimal imaging technique for diagnosing acute ischemic stroke, yet limited evidence is available on the value of DWI in the management of ischemic stroke with low-field magnetic resonance (MR) systems. Although high-field MR imaging (MRI) is desirable for DWI, low-field scanners provide an acceptable clinical compromise which is of importance to developing countries posed with the challenge of limited availability of high-field units. The purpose of this paper was to systematically review the literature on the usefulness of DWI in acute stroke management with low-field MRI scanners and present the experience in Nigeria. PMID:26709342

  9. Magnetic single-walled carbon nanotubes as efficient drug delivery nanocarriers in breast cancer murine model: noninvasive monitoring using diffusion-weighted magnetic resonance imaging as sensitive imaging biomarker

    PubMed Central

    Al Faraj, Achraf; Shaik, Abjal Pasha; Shaik, Asma Sultana

    2015-01-01

    allowed their sensitive noninvasive diagnosis using susceptibility-weighted MRI and their magnetic targeting using an externally applied magnet. Conclusion Enhanced therapeutic efficacy of DOX delivered through antibody-conjugated magnetic SWCNTs was achieved. Further, the superiority of apparent diffusion coefficient measurements using diffusion-weighted MRI was found to be a sensitive imaging biomarker for assessment of treatment-induced changes. PMID:25565811

  10. [Evaluation of diagnostic effectiveness of the method of diffusion-weighted MR-images in diagnosis of pathology of the uterine body].

    PubMed

    Stolyarova, I V; Yakovleva, E K; Sharakova, V V

    2015-01-01

    The purpose of this study was to evaluate diagnostic efficiency of methods of diffusion-weighted imaging (DWI) in the diagnosis of diseases of the body the uterus at the high and ultra high field MRI (1,5T1, 3,OT1). In total we examined 150 patients. In 72 patients (48%) there were histologically verified malignant changes; of these 70 patients (46.7%) had endome- trial cancer (EC), 2 (1.3%)--uterine sarcoma. 40 EC patients (57.2%) had of Stage I, 15 patients (21.4%)--Stage II, 11 patients (15.7%)--Stage III, and 4 patients (5.8%) of--stage IV. 48 patients (32%) had benign processes of the endometrium (uterine fibroids--27 patients, endometrial hyperplasia--12 patients, endometrial polyps--9 patients). The control group consisted of 30 (20%) healthy patients. All patients underwent MRI examination of the pelvic organs into high and ultra-high MRI (1,5T1, 3,0T1). All patients were required performance of SP DWI (diffusion-weighted images) in 2 projections (Ax and Sag) with different diffusion factors (50-500-1100). MRI data using DWI were compared with surgical material. To our opinion modern MRI techniques allow to reliably determine the size of the pathological process, its location, the extent of the parameters for endometrial cancer, as well as the degree of involvement in the pathological process of the bladder and rectum, to assess the condition of the pelvic lymph nodes. MRI, supplemented DWI, allowed differentiating benign and malignant lesions of the uterus. MRI data corresponded to a post mortem conclusion in the case, specificity 86%, sensitivity of 92% and a diagnostic accuracy of 91%, which significantly improved the diagnostic accuracy of a standard MRI. Thus the method DWI MRI using modern software improves the differential diagnosis of diseases of the body uterus, can reliably assess the extent of the pathological process, to fully assess the invasion of parametrial tissue, provide a comprehensive assessment of the status of the lymph nodes. PMID

  11. Reproducibility and optimization of in vivo human diffusion-weighted MRS of the corpus callosum at 3 T and 7 T.

    PubMed

    Wood, Emily T; Ercan, Ayse Ece; Branzoli, Francesca; Webb, Andrew; Sati, Pascal; Reich, Daniel S; Ronen, Itamar

    2015-08-01

    Diffusion-weighted MRS (DWS) of brain metabolites enables the study of cell-specific alterations in tissue microstructure by probing the diffusion of intracellular metabolites. In particular, the diffusion properties of neuronal N-acetylaspartate (NAA), typically co-measured with N-acetylaspartyl glutamate (NAAG) (NAA + NAAG = tNAA), have been shown to be sensitive to intraneuronal/axonal damage in pathologies such as stroke and multiple sclerosis. Lacking, so far, are empirical assessments of the reproducibility of DWS measures across time and subjects, as well as a systematic investigation of the optimal acquisition parameters for DWS experiments, both of which are sorely needed for clinical applications of the method. In this study, we acquired comprehensive single-volume DWS datasets of the human corpus callosum at 3 T and 7 T. We investigated the inter- and intra-subject variability of empirical and modeled diffusion properties of tNAA [D(avg) (tNAA) and D(model) (tNAA), respectively]. Subsequently, we used a jackknife-like resampling approach to explore the variance of these properties in partial data subsets reflecting different total scan durations. The coefficients of variation (C(V)) and repeatability coefficients (C(R)) for D(avg) (tNAA) and D(model) (tNAA) were calculated for both 3 T and 7 T, with overall lower variability in the 7 T results. Although this work is limited to the estimation of the diffusion properties in the corpus callosum, we show that a careful choice of diffusion-weighting conditions at both field strengths allows the accurate measurement of tNAA diffusion properties in clinically relevant experimental time. Based on the resampling results, we suggest optimized acquisition schemes of 13-min duration at 3T and 10-min duration at 7 T, whilst retaining low variability (C(V) ≈ 8%) for the tNAA diffusion measures. Power calculations for the estimation of D(model )(tNAA) and D(avg) (tNAA) based on the suggested schemes show that

  12. Variations in apparent diffusion coefficient values following chemotherapy in pediatric neuroblastoma

    PubMed Central

    Demir, Senay; Altinkaya, Naime; Kocer, Nazim Emrah; Erbay, Ayse; Oguzkurt, Pelin

    2015-01-01

    PURPOSE In children the assessment of solid tumors’ response to chemotherapy is based primarily on size reduction, which can be unreliable and a late marker, in the presence of necrosis. We aimed to establish whether apparent diffusion coefficient (ADC) values of childhood neuroblastomas show proportional changes in relation to chemotherapy response. METHODS We evaluated 15 pediatric patients with abdominopelvic neuroblastomas, who had undergone MRI before and after chemotherapy. Two radiologists retrospectively analyzed all images by drawing a round uniform region-of-interest in the solid/contrast-enhancing portion of the lesions in consensus. The ADC values from pre- and postchemotherapy images were compared. RESULTS Postchemotherapy ADC values were significantly higher than those obtained before treatment (P < 0.05, for minimum, maximum, and median ADC values). CONCLUSION Our results support diffusion-weighted MRI as a promising noninvasive biomarker of therapeutic responses. To the best of our knowledge, this is the first report to compare diffusion-weighted imaging findings before and after chemotherapy in childhood neuroblastic tumors. PMID:25519453

  13. Forecast experiment: do temporal and spatial b value variations along the Calaveras fault portend M ≥ 4.0 earthquakes?

    USGS Publications Warehouse

    Parsons, Tom

    2007-01-01

    The power law distribution of earthquake magnitudes and frequencies is a fundamental scaling relationship used for forecasting. However, can its slope (b value) be used on individual faults as a stress indicator? Some have concluded that b values drop just before large shocks. Others suggested that temporally stable low b value zones identify future large-earthquake locations. This study assesses the frequency of b value anomalies portending M ≥ 4.0 shocks versus how often they do not. I investigated M ≥ 4.0 Calaveras fault earthquakes because there have been 25 over the 37-year duration of the instrumental catalog on the most active southern half of the fault. With that relatively large sample, I conducted retrospective time and space earthquake forecasts. I calculated temporal b value changes in 5-km-radius cylindrical volumes of crust that were significant at 90% confidence, but these changes were poor forecasters of M ≥ 4.0 earthquakes. M ≥ 4.0 events were as likely to happen at times of high b values as they were at low ones. However, I could not rule out a hypothesis that spatial b value anomalies portend M ≥ 4.0 events; of 20 M ≥ 4 shocks that could be studied, 6 to 8 (depending on calculation method) occurred where b values were significantly less than the spatial mean, 1 to 2 happened above the mean, and 10 to 13 occurred within 90% confidence intervals of the mean and were thus inconclusive. Thus spatial b value variation might be a useful forecast tool, but resolution is poor, even on seismically active faults.

  14. Preoperative diagnosis and staging of rectal cancer using diffusion-weighted and water imaging combined with dynamic contrast-enhanced scanning

    PubMed Central

    ZHAO, QILI; LIU, LIJIAN; WANG, QIUYAN; LIANG, ZEXIA; SHI, GAOFENG

    2014-01-01

    The aim of the present study was to evaluate the value of diffusion-weighted imaging (DWI) and water imaging combined with dynamic contrast-enhanced scanning for the preoperative diagnosis and staging of rectal cancer. In total, 72 patients with pathologically confirmed rectal cancer were selected for examination using magnetic resonance imaging (MRI) with phased-array coils, DWI, water imaging and dynamic contrast-enhanced scanning. The patients were divided into two groups, experimental (simple enhanced scanning plus diffusion combined with water imaging) and control (simple enhanced scanning), for the pathological observations. The sensitivity, specificity and accuracy for the T staging of the carcinomas using scan enhancement with DWI and the evaluation of cancer using water imaging were 98.5% (65/66), 66.7% (4/6) and 95.8% (69/72), respectively, and the accuracy for N staging was 89%. Whereas, the sensitivity, specificity and accuracy for the T staging of the carcinomas using simple scan enhancement were 85.7% (42/49), 78.3% (18/23) and 83.3% (60/72), respectively, and the accuracy for N staging was 61%. Therefore, the combination of multiple MRI techniques may be of high value for the early diagnosis and exact staging of rectal cancer. PMID:25360178

  15. High-resolution three-dimensional diffusion-weighted MRI/CT image data fusion for cholesteatoma surgical planning: a feasibility study.

    PubMed

    Yamashita, Koji; Hiwatashi, Akio; Togao, Osamu; Kikuchi, Kazufumi; Matsumoto, Nozomu; Obara, Makoto; Yoshiura, Takashi; Honda, Hiroshi

    2015-12-01

    The aim of the study was to assess the feasibility of high-resolution three-dimensional diffusion-weighted images (HR3D-DWIs)/multi-detector row CT (MDCT) images' data fusion for surgical planning for cholesteatoma. A total of 12 patients (7 male and 5 female; age range 11-72 years; mean 38.1 years) with cholesteatoma underwent preoperative MRI using a 3.0-T clinical unit and an 8-channel array-head coil. For each subject, HR3D-DWIs were obtained using a turbo field-echo with diffusion-sensitized driven-equilibrium preparation with 1.5 mm iso-voxel dimension. These patients also underwent MDCT with a slice thickness of 0.5 mm. Fusion of the HR3D-DWIs and MDCT images was performed using an automated rigid registration and subsequent manual fine-tuning by a board-certified neuroradiologist on a workstation. Fused images were compared to CT and findings confirmed based on operation reports. On the fused images, the extent of the cholesteatoma, which was depicted as a conspicuous high-intensity lesion could be easily evaluated with background bony structures. In all patients, the location and extent of the cholesteatoma on the fused images corresponded well with the intraoperative findings. Image fusion between HR3D-DWIs and MDCT images is feasible, and provides valuable preoperative information for surgical planning to otorhinolaryngologists. PMID:25543305

  16. Staging of Primary Abdominal Lymphomas: Comparison of Whole-Body MRI with Diffusion-Weighted Imaging and 18F-FDG-PET/CT

    PubMed Central

    Stecco, Alessandro; Buemi, Francesco; Quagliozzi, Martina; Lombardi, Mariangela; Santagostino, Alberto; Sacchetti, Gian Mauro; Carriero, Alessandro

    2015-01-01

    Background. The purpose of this study was to compare the accuracy of whole-body MRI with diffusion-weighted sequences (WB-DW-MRI) with that of 18F-FDG-PET/CT in the staging of patients with primary gastrointestinal lymphoma. Methods. This retrospective study involved 17 untreated patients with primary abdominal gastrointestinal lymphoma. All patients underwent 18F-FDG-PET/CT and WB-DW-MRI. Histopathology findings or at least 6 months of clinical and radiological follow-up was the gold standard. The Musshoff-modified Ann Arbor system was used for staging, and diagnostic accuracy was evaluated on a per-node basis. Results. WB-DW-MRI exhibited 100% sensitivity, 96.3% specificity, and 96.1% and 100% positive and negative predictive values (PPV and NPV), respectively. The sensitivity, specificity, and PPV and NPV of PET/CT were 95.9%, 100%, and 100% and 96.4%, respectively. There were no statistically significant differences between the two techniques (p = 0.05). The weighted kappa agreement statistics with a 95% confidence interval were 0.97 (0.95–0.99) between the two MRI readers and 0.87 (0.82–0.92) between the two methods. Conclusions. WB-DW-MRI appears to have a comparable diagnostic value to 18F-FDG-PET/CT in staging patients with gastrointestinal lymphoma. PMID:26798331

  17. The Role of Diffusion-Weighted Imaging (DWI) in Locoregional Therapy Outcome Prediction and Response Assessment for Hepatocellular Carcinoma (HCC): The New Era of Functional Imaging Biomarkers.

    PubMed

    Ludwig, Johannes M; Camacho, Juan C; Kokabi, Nima; Xing, Minzhi; Kim, Hyun S

    2015-01-01

    Reliable response criteria are critical for the evaluation of therapeutic response in hepatocellular carcinoma (HCC). Current response assessment is mainly based on: (1) changes in size, which is at times unreliable and lag behind the result of therapy; and (2) contrast enhancement, which can be difficult to quantify in the presence of benign post-procedural changes and in tumors presenting with a heterogeneous pattern of enhancement. Given these challenges, functional magnetic resonance imaging (MRI) techniques, such as diffusion-weighted imaging (DWI) have been recently investigated, aiding specificity to locoregional therapy response assessment and outcome prediction. Briefly, DWI quantifies diffusion of water occurring naturally at a cellular level (Brownian movement), which is restricted in multiple neoplasms because of high cellularity. Disruption of cellular integrity secondary to therapy results in increased water diffusion across the injured membranes. This review will provide an overview of the current literature on DWI therapy response assessment and outcome prediction in HCC following treatment with locoregional therapies. PMID:26854170

  18. The Role of Diffusion-Weighted Imaging (DWI) in Locoregional Therapy Outcome Prediction and Response Assessment for Hepatocellular Carcinoma (HCC): The New Era of Functional Imaging Biomarkers

    PubMed Central

    Ludwig, Johannes M.; Camacho, Juan C.; Kokabi, Nima; Xing, Minzhi; Kim, Hyun S.

    2015-01-01

    Reliable response criteria are critical for the evaluation of therapeutic response in hepatocellular carcinoma (HCC). Current response assessment is mainly based on: (1) changes in size, which is at times unreliable and lag behind the result of therapy; and (2) contrast enhancement, which can be difficult to quantify in the presence of benign post-procedural changes and in tumors presenting with a heterogeneous pattern of enhancement. Given these challenges, functional magnetic resonance imaging (MRI) techniques, such as diffusion-weighted imaging (DWI) have been recently investigated, aiding specificity to locoregional therapy response assessment and outcome prediction. Briefly, DWI quantifies diffusion of water occurring naturally at a cellular level (Brownian movement), which is restricted in multiple neoplasms because of high cellularity. Disruption of cellular integrity secondary to therapy results in increased water diffusion across the injured membranes. This review will provide an overview of the current literature on DWI therapy response assessment and outcome prediction in HCC following treatment with locoregional therapies. PMID:26854170

  19. Development of Computerized Scheme for Adjustment of Display Grayscale in Brain Diffusion-Weighted Magnetic Resonance Images with Acute Ischemic Stroke

    NASA Astrophysics Data System (ADS)

    Nagashima, Hiroyuki; Harakawa, Tetsumi; Doi, Kunio

    We developed a computerized scheme for proper adjustment of display grayscale in brain diffusion-weighted magnetic resonance images (DWI) with acute ischemic stroke by using thalamic signal intensity on concurrent images (b0 image). In our computerized scheme, the gray level of b0 image was first normalized, and the brain region was segmented using thresholding and labeling techniques. The lateral inclination in b0 image was then corrected semi-automatically by rotating and shifting. Each of the thalamic positions was determined by using the coordinate information in the brain region. The average signal intensity of the thalamus was measured on the region of interest (ROI) selected, and the thalamus in one side with the low signal intensity was selected. The display grayscale in DWI was finally adjusted by using the signal intensity of the selected thalamus. The thalamus positions in all cases were confirmed to be included in the thalamic outline. In 30 training cases, the average error between the thalamic signal intensity obtained from the manual selection and the computerized scheme were 1.8%±1.5, and in 30 testing cases, 1.3%±1.2. Our computerized scheme has a potential in the determination of the display grayscale of brain DWI, and would be useful to radiologists in decision-making for radiological diagnosis.

  20. MR imaging of urinary bladder cancer for T-staging: a review and a pictorial essay of diffusion-weighted imaging.

    PubMed

    Takeuchi, Mitsuru; Sasaki, Shigeru; Naiki, Taku; Kawai, Noriyasu; Kohri, Kenjiro; Hara, Masaki; Shibamoto, Yuta

    2013-12-01

    Treatment decisions for bladder cancer patients are mainly based on the depth of bladder wall invasion by the tumor. In this article, we review the conventional MRI and exhibit a recently emerged diffusion-weighted imaging (DWI) of urinary bladder cancer for T-staging. We discuss limitations of conventional MRI, scanning protocols of DWI, normal pelvic findings on DWI, determination of T-stage using DWI, and pitfalls of DWI. DWI provides high contrast between bladder cancer and background tissue because the cancer shows markedly high SI. DWI has high sensitivity for detecting the stalk seen in stage Ta or T1. An inflammatory change or fibrosis surrounding the tumor mimics the invasion of bladder cancer on T2-weighted imaging or enhanced MRI and could lead to over-staging, but DWI could differentiate them clearly because these benign changes do not show high SI on DWI. DWI is also useful for detecting ureteral, urethral, and prostatic extension by means of the urethra. DWI provides more accurate information on the extent of bladder cancer and contributes to determination of the treatment strategy. PMID:24265260

  1. Diffusion-weighted whole-body imaging with background body signal suppression/T2-weighted image fusion of gastrointestinal cancers

    PubMed Central

    TOMIZAWA, MINORU; SHINOZAKI, FUMINOBU; FUGO, KAZUNORI; SUNAOSHI, TAKAFUMI; KANO, DAISUKE; TANAKA, SATOMI; OZAKI, AIKA; SUGIYAMA, ERIKO; SHITE, MISAKI; HAGA, RYOUTA; BABA, AKIRA; FUKAMIZU, YOSHIYA; FUJITA, TOSHIYUKI; KAGAYAMA, SATOSHI; HASEGAWA, RUMIKO; TOGAWA, AKIRA; SHIRAI, YOSHINORI; ICHIKI, NOBORU; MOTOYOSHI, YASUFUMI; SUGIYAMA, TAKAO; YAMAMOTO, SHIGENORI; KISHIMOTO, TAKASHI; ISHIGE, NAOKI

    2016-01-01

    Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) yields positive results for cancer against the surrounding tissues. The combination of DWIBS and T2-weighted images (DWIBS/T2) in the diagnosis of gastrointestinal tract cancers was retrospectively analyzed in the present study. Patients were subjected to magnetic resonance imaging after cancer was diagnosed through specimens obtained via biopsy or endoscopic mucosal resection. Sixteen patients were assessed between July, 2012 and June, 2013 and the correlation between detection with DWIBS/T2 and T staging was analyzed. Regarding patients who underwent surgery, the correlation between detection with DWIBS/T2 and the diameter or depth of invasion was analyzed. All cancers that had advanced to >T2 stage were detectable by DWIBS/T2, whereas all cancers staged as T2) or invading beyond the muscularis propria. PMID:27330763

  2. Reduced Integration and Differentiation of the Imitation Network in Autism: A Combined Functional Connectivity Magnetic Resonance Imaging and Diffusion-Weighted Imaging Study

    PubMed Central

    Fishman, Inna; Datko, Michael; Cabrera, Yuliana; Carper, Ruth A.; Müller, Ralph-Axel

    2016-01-01

    Objective Converging evidence indicates that brain abnormalities in autism spectrum disorder (ASD) involve atypical network connectivity, but few studies have integrated functional with structural connectivity measures. This multimodal investigation examined functional and structural connectivity of the imitation network in children and adolescents with ASD, and its links with clinical symptoms. Methods Resting state functional magnetic resonance imaging and diffusion-weighted imaging were performed in 35 participants with ASD and 35 typically developing controls, aged 8 to 17 years, matched for age, gender, intelligence quotient, and head motion. Results Within-network analyses revealed overall reduced functional connectivity (FC) between distributed imitation regions in the ASD group. Whole brain analyses showed that underconnectivity in ASD occurred exclusively in regions belonging to the imitation network, whereas overconnectivity was observed between imitation nodes and extraneous regions. Structurally, reduced fractional anisotropy and increased mean diffusivity were found in white matter tracts directly connecting key imitation regions with atypical FC in ASD. These differences in microstructural organization of white matter correlated with weaker FC and greater ASD symptomatology. Interpretation Findings demonstrate atypical connectivity of the brain network supporting imitation in ASD, characterized by a highly specific pattern. This pattern of underconnectivity within, but overconnectivity outside the functional network is in contrast with typical development and suggests reduced network integration and differentiation in ASD. Our findings also indicate that atypical connectivity of the imitation network may contribute to ASD clinical symptoms, highlighting the role of this fundamental social cognition ability in the pathophysiology of ASD. PMID:26418284

  3. Diffusion-weighted MRI in early chemotherapy response evaluation of patients with diffuse large B-cell lymphoma--a pilot study: comparison with 2-deoxy-2-fluoro- D-glucose-positron emission tomography/computed tomography.

    PubMed

    Wu, Xingchen; Kellokumpu-Lehtinen, Pirkko-Liisa; Pertovaara, Hannu; Korkola, Pasi; Soimakallio, Seppo; Eskola, Hannu; Dastidar, Prasun

    2011-12-01

    To determine the feasibility of diffusion-weighted MRI (DWI) in the evaluation of the early chemotherapeutic response in patients with aggressive non-Hodgkin's lymphoma (NHL), eight patients with histologically proven diffuse large B-cell lymphoma were imaged by MRI, including DWI, and positron emission tomography/computed tomography (PET/CT) before treatment (E1), and after 1 week (E2) and two cycles (E3) of chemotherapy. In all patients, whole-body screening using T(1) - and T(2) -weighted images in the coronal plane was performed. To quantitatively evaluate the chemotherapeutic response, axial images including DWI were acquired. Apparent diffusion coefficient (ADC) maps were reconstructed, and the ADC value of the tumor was measured. In addition, the tumor volume was estimated on axial T(2) -weighted images. The maximum standardized uptake value (SUV(max) ) and active tumor volume were measured on fused PET/CT images. Lymphomas showed high signal intensity on DW images and low signal intensity on ADC maps, except for necrotic foci. The mean pre-therapy ADC was 0.71 × 10(-3) mm(2) /s; it increased by 77% at E2 (p < 0.05) and 24% more at E3 (insignificant); the total increase was 106% (p < 0.05). The mean tumor volume by MRI was 276 mL at baseline; it decreased by 58% at E2 (p < 0.05) and 65% more at E3 (p < 0.05), giving a total decrease of 84% (p < 0.05). All the imaged pre-therapy tumors were strongly positive on PET/CT, with a mean SUV(max) of 20. The SUV(max) decreased by 60% at E2 (p < 0.05) and 59% more at E3 (p < 0.05), giving a total decrease of 83% (p < 0.05). The active tumor burden decreased by 66% at E2 (p < 0.05). At baseline, both central and peripheral tumor ADC values correlated inversely with SUV(max) (p < 0.05), and also correlated inversely with active tumor burden on PET/CT and with tumor volume on MRI at E2 (p < 0.05). In conclusion, the results of DWI in combination with whole-body MRI were

  4. Preoperative prediction of neurovascular bundle involvement of localized prostate cancer by combined T2 and diffusion-weighted imaging of magnetic resonance imaging, number of positive biopsy cores, and Gleason score.

    PubMed

    Naiki, Taku; Okamura, Takehiko; Nagata, Daisuke; Mori, Yuji; Kawai, Noriyasu; Ogawa, Kumiko; Akita, Hidetoshi; Hashimoto, Yoshihiro; Tozawa, Keiichi; Kohri, Kenjiro

    2011-01-01

    Because recovery of erectile function and avoidance of positive surgical margins are important but competing outcomes with prostate cancer therapy, the decision to preserve or resect a neurovascular bundle (NVB) during laparoscopic radical prostatectomy (LRP) should be firmly based on information concerning the presence and location of extracapsular extension. In the current retrospective study, the propriety of actual decisions was assessed using preoperative magnetic resonance imaging (MRI), combining T2-weighted imaging (T2WI) with diffusion-weighted imaging (DWI), the apparent diffusion coefficient (ADC), numbers of positive biopsy cores, tumor volume and the Gleason score. MRI before prostate biopsy was performed in 35 patients who underwent LRP for clinically localized prostate cancer. A single radiologist retrospectively assessed whether the tumor localization, capsular penetration, seminal vesicle invasion, NVB involvement, and MRI findings correlated with the postoperative histological results. With the postoperative specimens, 83 lesions demonstrated a Gleason score of 6 or more. Using T2WI with and without DWI and ADC, 39 and 27 of 54 lesions were correctly identified, respectively, the difference being significant. For cancers in the transitional zone, using a threshold Gleason score of 3 or greater, sensitivity was also significantly higher for T2+DWI+ADC than for T2WI alone. Of 35 patients, using all available clinical information (biopsy results including Gleason score, tumor location, percentage of positive biopsy cores, and the percentage of tumor-involved core tissue), we found that the preoperative and postoperative staging were concordant in 25 cases. There is no universal consensus for nerve-sparing LRP; therefore, we performed an additional analysis using simplified clinically defined selection criteria (PSA level >15ng/mL, cT2, less than two positive biopsy scores in the unilateral lobe and less than 30% tumor volume, and a Gleason score of 6

  5. Metabolomics of Breast Cancer Using High-Resolution Magic Angle Spinning Magnetic Resonance Spectroscopy: Correlations with 18F-FDG Positron Emission Tomography-Computed Tomography, Dynamic Contrast-Enhanced and Diffusion-Weighted Imaging MRI

    PubMed Central

    Yoon, Haesung; Yoon, Dahye; Yun, Mijin; Choi, Ji Soo; Park, Vivian Youngjean; Kim, Eun-Kyung; Jeong, Joon; Koo, Ja Seung; Yoon, Jung Hyun; Moon, Hee Jung; Kim, Suhkmann; Kim, Min Jung

    2016-01-01

    Purpose Our goal in this study was to find correlations between breast cancer metabolites and conventional quantitative imaging parameters using high-resolution magic angle spinning (HR-MAS) magnetic resonance spectroscopy (MRS) and to find breast cancer subgroups that show high correlations between metabolites and imaging parameters. Materials and methods Between August 2010 and December 2013, we included 53 female patients (mean age 49.6 years; age range 32–75 years) with a total of 53 breast lesions assessed by the Breast Imaging Reporting and Data System. They were enrolled under the following criteria: breast lesions larger than 1 cm in diameter which 1) were suspicious for malignancy on mammography or ultrasound (US), 2) were pathologically confirmed to be breast cancer with US-guided core-needle biopsy (CNB) 3) underwent 3 Tesla MRI with dynamic contrast-enhanced (DCE) and diffusion-weighted imaging (DWI) and positron emission tomography-computed tomography (PET-CT), and 4) had an attainable immunohistochemistry profile from CNB. We acquired spectral data by HR-MAS MRS with CNB specimens and expressed the data as relative metabolite concentrations. We compared the metabolites with the signal enhancement ratio (SER), maximum standardized FDG uptake value (SUV max), apparent diffusion coefficient (ADC), and histopathologic prognostic factors for correlation. We calculated Spearman correlations and performed a partial least squares-discriminant analysis (PLS-DA) to further classify patient groups into subgroups to find correlation differences between HR-MAS spectroscopic values and conventional imaging parameters. Results In a multivariate analysis, the PLS-DA models built with HR-MAS MRS metabolic profiles showed visible discrimination between high and low SER, SUV, and ADC. In luminal subtype breast cancer, compared to all cases, high SER, ADV, and SUV were more closely clustered by visual assessment. Multiple metabolites were correlated with SER and SUV in

  6. Correlations between the MR Diffusion-weighted Image (DWI) and the bone mineral density (BMD) as a function of the soft tissue thickness-focus on phantom and patient

    NASA Astrophysics Data System (ADS)

    Kim, Myung-Sam; Cho, Jae-Hwan; Lee, Hae-Kag; Lee, Sang-Jeong; Park, Cheol-Soo; Dong, Kyung-Rae; Park, Yong-Soon; Chung, Woon-Kwan; Lee, Jong-Woong; Kim, Ho-Sung; Kim, Eun-Hye; Kweon, Dae Cheol; Yeo, Hwa-Yeon

    2013-02-01

    In this study we used lumbar phantoms to determine if the BMD (bone mineral density) changes when only the thickness of soft tissue is increased. Second, we targeted osteoporosis patients to analyze the dependences of the changes in the SNR (signal-to-noise ratio) and the ADC (apparent diffusion coefficient) on changes in T-score. We used a bone mineral densitometer, phantoms such as an aluminum spine phantom (ASP), a Hologic spine phantom (HSP), and a European spine phantom (ESP), five sheets of acrylic panel, and a water bath to study the effects of changes in the thickness of soft tissue. First, we measured the ASP, the HSP and the ESP. For the measurement of the ASP, we filled it with water to increase the height by 0.5 cm starting from the baseline height. We then did three measurements for each height. For the measurements of the HSP and the ESP, we placed an acrylic panel on the phantom and then did three measurements at each height. We used the ASP to calculate the degree of precision of the standard mode and the thick mode at the maximum height of the water bath. To assess the degree of precision in the measurements of the three types of phantoms, we calculated precision errors and analyzed the correlation between the change in the thickness of soft tissue and the variables of the BMD. Using DWIs (diffusion weighted images), we targeted 30 healthy persons without osteoporosis and 30 patients with a finding of osteoporosis and measured the T-scores for the L1 — L4 (lumbar spine) segments of by the spine using the dual-energy X-ray absorptiometry (DXA) before classifying the measurement at each part of the spine as osteopenia or osteoporosis. We measured the signal intensity on all four parts of L1-L4 in the DWIs obtained using a 1.5T MR scanner and measured the ADC in the ADC map image. We compared changes in the SNR and the ADC for each group. The study results confirmed that an increase in the thickness of the soft tissue had a significant correlation

  7. Clinical Utility of Multimodality Imaging with Dynamic Contrast-Enhanced MRI, Diffusion-Weighted MRI, and 18F-FDG PET/CT for the Prediction of Neck Control in Oropharyngeal or Hypopharyngeal Squamous Cell Carcinoma Treated with Chemoradiation

    PubMed Central

    Chan, Sheng-Chieh; Lin, Yu-Chun; Yen, Tzu-Chen; Liao, Chun-Ta; Chang, Joseph Tung-Chieh; Ko, Sheung-Fat; Wang, Hung- Ming; Chang, Chee-Jen; Wang, Jiun-Jie

    2014-01-01

    The clinical usefulness of pretreatment imaging techniques for predicting neck control in patients with oropharyngeal or hypopharyngeal squamous cell carcinoma (OHSCC) treated with chemoradiation remains unclear. In this prospective study, we investigated the role of pretreatment dynamic contrast-enhanced perfusion MR imaging (DCE-PWI), diffusion-weighted MR imaging (DWI), and [18F]fluorodeoxyglucose-positron emission tomography (18F-FDG PET)/CT derived imaging markers for the prediction of neck control in OHSCC patients treated with chemoradiation. Patients with untreated OHSCC scheduled for chemoradiation between August, 2010 and July, 2012 were eligible for the study. Clinical variables and the following imaging parameters of metastatic neck lymph nodes were examined in relation to neck control: transfer constant, volume of blood plasma, and volume of extracellular extravascular space (Ve) on DCE-PWI; apparent diffusion coefficient (ADC) on DWI; maximum standardized uptake value, metabolic tumor volume, and total lesion glycolysis on 18F-FDG PET/CT. There were 69 patients (37 with oropharynx SCC and 32 with hypopharynx SCC) with successful pretreatment DCE-PWI and DWI available for analysis. After a median follow-up of 31 months, 25 (36.2%) participants had neck failure. Multivariate analysis identified hemoglobin level <14.3 g/dL (P = 0.019), Ve <0.23 (P = 0.040), and ADC >1.14×10−3 mm2/s (P = 0.003) as independent prognostic factors for 3-year neck control. A prognostic scoring system was formulated by summing up the three significant predictors of neck control. Patients with scores of 2–3 had significantly poorer neck control and overall survival rates than patients with scores of 0–1. We conclude that hemoglobin levels, Ve, and ADC are independent pretreatment prognostic factors for neck control in OHSCC treated with chemoradiation. Their combination may identify a subgroup of patients at high risk of developing neck failure. PMID:25531391

  8. Foreshocks and b Value: Bridging Macroscopic Observations to Source Mechanical Considerations

    NASA Astrophysics Data System (ADS)

    Avlonitis, M.; Papadopoulos, G. A.

    2014-10-01

    Spring-block models, such as the Olami-Feder-Christensen (OFC) model, were introduced several years ago to describe earthquake dynamics in the context of self-organized criticality. With the aim to address the dependency of the seismicity style on source's material properties, we present an analytical enrichment of a 2D OFC model. We conclude with an analytical expression which introduces, through an appropriate constitutive equation, an effective dissipation parameter a eff related analytically not only with the elastic properties of the fault plane, but also with stochastic structural heterogeneities and structural processes of the source through a gradient coefficient. Moreover, within the proposed formulation, the low b values experimentally observed in foreshock sequences can be modeled by a process of material softening in the seismogenic volume. To check our analytical findings, a cellular automaton was built-up whereas simulation results have verified the model's predictions for the evolution of b in macroscopic records.

  9. Combined value of apparent diffusion coefficient-standardized uptake value max in evaluation of post-treated locally advanced rectal cancer

    PubMed Central

    Ippolito, Davide; Fior, Davide; Trattenero, Chiara; Ponti, Elena De; Drago, Silvia; Guerra, Luca; Franzesi, Cammillo Talei; Sironi, Sandro

    2015-01-01

    AIM: To assess the clinical diagnostic value of functional imaging, combining quantitative parameters of apparent diffusion coefficient (ADC) and standardized uptake value (SUV)max, before and after chemo-radiation therapy, in prediction of tumor response of patients with rectal cancer, related to tumor regression grade at histology. METHODS: A total of 31 patients with biopsy proven diagnosis of rectal carcinoma were enrolled in our study. All patients underwent a whole body 18FDG positron emission tomography (PET)/computed tomography (CT) scan and a pelvic magnetic resonance (MR) examination including diffusion weighted (DW) imaging for staging (PET1, RM1) and after completion (6.6 wk) of neoadjuvant treatment (PET2, RM2). Subsequently all patients underwent total mesorectal excision and the histological results were compared with imaging findings. The MR scanning, performed on 1.5 T magnet (Philips, Achieva), included T2-weighted multiplanar imaging and in addition DW images with b-value of 0 and 1000 mm²/s. On PET/CT the SUVmax of the rectal lesion were calculated in PET1 and PET2. The percentage decrease of SUVmax (ΔSUV) and ADC (ΔADC) values from baseline to presurgical scan were assessed and correlated with pathologic response classified as tumor regression grade (Mandard’s criteria; TRG1 = complete regression, TRG5 = no regression). RESULTS: After completion of therapy, all the patients were submitted to surgery. According to the Mandard’s criteria, 22 tumors showed complete (TRG1) or subtotal regression (TRG2) and were classified as responders; 9 tumors were classified as non responders (TRG3, 4 and 5). Considering all patients the mean values of SUVmax in PET 1 was higher than the mean value of SUVmax in PET 2 (P < 0.001), whereas the mean ADC values was lower in RM1 than RM2 (P < 0.001), with a ΔSUV and ΔADC respectively of 60.2% and 66.8%. The best predictors for TRG response were SUV2 (threshold of 4.4) and ADC2 (1.29 × 10-3 mm2/s) with high

  10. Decade-scale decrease in b value prior to the M9-class 2011 Tohoku and 2004 Sumatra quakes

    NASA Astrophysics Data System (ADS)

    Nanjo, K. Z.; Hirata, N.; Obara, K.; Kasahara, K.

    2012-10-01

    The Gutenberg-Richter frequency-magnitude distribution of earthquakes has become well established in seismology. The slope of the relation between frequency and magnitude (b value) is typically 1, but it often shows variations around 1. Based on an analysis of seismicity prior to the 2011 Tohoku and 2004 Sumatra earthquakes (both in magnitude (M) 9 class), we show that the pronounced decade-scale decrease in b value was a common precursor to both mega-quakes around their hypocenters. This is the first report on M9-class quakes to confirm a change in b value, which has been predicted based on the results of laboratory experiments. We propose that the b value is an important indicator of an impending great earthquake, and has great potential in terms of predicting a future large quake off the Pacific coast of Hokkaido, Japan.

  11. Intraventricular cerebrospinal fluid temperature analysis using MR diffusion-weighted imaging thermometry in Parkinson's disease patients, multiple system atrophy patients, and healthy subjects

    PubMed Central

    Sumida, Kaoru; Sato, Noriko; Ota, Miho; Sakai, Koji; Nippashi, Yasumasa; Sone, Daichi; Yokoyama, Kota; Ito, Kimiteru; Maikusa, Norihide; Imabayashi, Etsuko; Matsuda, Hiroshi; Yamada, Kei; Murata, Miho; Kunimatsu, Akira; Ohtomo, Kuni

    2015-01-01

    Purpose We examined the temperature of the intraventricular cerebrospinal fluid (Tv) in patients with Parkinson's disease (PD) and those with multiple system atrophy (MSA) in comparison with healthy subjects, and we examined normal changes in this temperature with aging. Methods Tv was estimated by magnetic resonance (MR) diffusion-weighted imaging (DWI) thermometry in 36 PD patients (19 males, 17 females), 34 MSA patients (17 males, 17 females), 64 age-matched controls (27 men, 37 women), and 114 all-age adult controls (47 men, 67 women; 28–89 years old). The volume of lateral ventricles was also estimated using FreeSurfer in all subjects. Tv and ventricular volume data were compared among the PD and MSA patients and age-matched controls. We also evaluated the relationship between Tv and age in the 114 all-age controls, controlling for ventricular volume. Men and women were analyzed separately. Results The male PD and MSA patients had significantly higher Tv values compared to the male controls, with no significant difference in ventricular volume among them. There was no significant difference in Tv between the female patients and controls. In the all-age male controls, there was a significant negative correlation between Tv and age controlling for ventricular volume, and this was not observed in the women. Conclusion DWI thermometry is a useful and easy method for demonstrating an altered intracranial environment in male patients and healthy controls, but not in females. DWI thermometry can thus be used to help to explore the pathophysiology of Parkinsonian syndromes and to differentiate individuals affected by neurodegenerative disease with autonomic dysfunction from those without it. PMID:26085965

  12. Analysis of factors influencing the degree of detectability on diffusion-weighted MRI and diffusion background signals in patients with invasive breast cancer.

    PubMed

    Hahn, Soo Yeon; Ko, Eun Sook; Han, Boo-Kyung; Lim, Yaeji; Gu, Seonhye; Ko, Eun Young

    2016-07-01

    To determine the factors influencing the degree of detectability of lesions and diffusion background signals on magnetic resonance diffusion-weighted imaging (DWI) in invasive breast cancer.Institutional review board approval was obtained and patient consent was waived. Patients with newly diagnosed invasive ductal carcinoma, who underwent preoperative breast magnetic resonance imaging with DWI were included in this study (n = 167). Lesion detectability on DWI and contrast-enhanced subtracted T1-weighted images, the degree of background parenchymal enhancement (BPE), and diffusion background signal were qualitatively rated. Detectability of lesions on DWI was compared with clinicopathological findings including menopausal status, mammographic density, and molecular subtype of breast cancer. Multivariate linear regression analysis was performed to determine variables independently associated with detectability of lesions on DWI and diffusion background signals.Univariate analysis showed that the detectability of lesions on DWI was significantly associated with lesion size (P = 0.001), diffuse background signal (P < 0.0001), and higher detectability scores for contrast-enhanced T1-weighted subtraction images (P = 0.000). The degree of diffusion background signal was significantly affected by age (P < 0.0001), BPE (P < 0.0001), mammographic density (P = 0.002), and menopausal status (P < 0.0001). On multivariate analysis, the diffusion background signal (P < 0.0001) and histologic grade (P < 0.0001) were correlated with the detectability on DWI of invasive breast cancer. Only BPE was correlated with the amount of diffusion background signal on DWI (P < 0.0001).For invasive breast cancers, detectability on DWI was significantly affected by the diffusion background signal. BPE, menopausal status, menstrual cycle, or mammographic density did not show statistically significant correlation with the diffusion detectability of lesions on DWI. PMID

  13. Bone metastases from prostate, breast and multiple myeloma: differences in lesion conspicuity at short-tau inversion recovery and diffusion-weighted MRI

    PubMed Central

    Pearce, T; Philip, S; Brown, J; Koh, D M; Burn, P R

    2012-01-01

    Objectives The objective of this study was to compare the relative conspicuity of bone metastases on short-tau inversion recovery (STIR) and diffusion-weighted MRI (DWI) whole-body MR sequences for breast, prostate and myeloma malignancies. Methods 44 whole-body MRI scans were reviewed retrospectively (coronal T1 weighted, STIR and DWI with b=800). On each scan, up to four of the largest bone lesions were identified on T1 weighting, and the region of interest signal intensity was measured on STIR and DWI, as well as the background signal intensity. The mean lesion signal to background ratio was calculated for each patient and then for each malignancy group. Results In prostate cancer patients, the DWI signal/background ratio was greater than that of STIR in 22 out of 24 patients (mean DWI lesion/background ratio 3.91, mean STIR lesion/background ratio 2.31; p=0.0001). In multiple myeloma, the DWI ratio was higher in 6/7 patients (DWI group mean ratio 7.59, STIR group mean ratio 3.7; p=0.0366). In 13 breast cancer patients, mean STIR and DWI signal/background were similar (DWI group mean ratio 4.13, group mean STIR ratio 4.26; p=0.8587). Conclusion Bone lesion conspicuity measured by lesion/background signal intensity was higher on DWI b=800 than on STIR in patients with prostate cancer and multiple myeloma. DWI should be used in whole-body MR oncology protocols in these conditions to maximise lesion detection. PMID:22457319

  14. Carotid Anatomy Does Not Predict the Risk of New Ischaemic Brain Lesions on Diffusion-Weighted Imaging after Carotid Artery Stenting in the ICSS-MRI Substudy

    PubMed Central

    Doig, D.; Hobson, B.M.; Müller, M.; Jäger, H.R.; Featherstone, R.L.; Brown, M.M.; Bonati, L.H.; Richards, T.

    2016-01-01

    Introduction The International Carotid Stenting Study (ICSS, ISRCTN25337470) randomized patients with recently symptomatic carotid artery stenosis > 50% to carotid artery stenting (CAS) or endarterectomy. CAS increased the risk of new brain lesions visible on diffusion-weighted magnetic resonance imaging (DWI-MRI) more than endarterectomy in the ICSS-MRI Substudy. The predictors of new post-stenting DWI lesions were assessed in these patients. Methods ICSS-MRI Substudy patients allocated to CAS were studied. Baseline or pre-stenting catheter angiograms were rated to determine carotid anatomy. Baseline patient demographics and the influence of plaque length, plaque morphology, internal carotid angulation, and external or common carotid atheroma were examined in negative binomial regression models. Results A total of 115 patients (70% male, average age 70.4) were included; 50.4% had at least one new DWI-MRI-positive lesion following CAS. Independent risk factors increasing the number of new lesions were a left-sided stenosis (incidence risk ratio [IRR] 1.59, 95% CI 1.04–2.44, p = .03), age (IRR 2.10 per 10-year increase in age, 95% CI 1.61–2.74, p < .01), male sex (IRR 2.83, 95% CI 1.72–4.67, p < .01), hypertension (IRR 2.04, 95% CI 1.25–3.33, p < .01) and absence of cardiac failure (IRR 6.58, 95% CI 1.23–35.07, p = .03). None of the carotid anatomical features significantly influenced the number of post-procedure lesions. Conclusion Carotid anatomy seen on pre-stenting catheter angiography did not predict of the number of ischaemic brain lesions following CAS. PMID:26481656

  15. Comparison of [{sup 11}C]choline Positron Emission Tomography With T2- and Diffusion-Weighted Magnetic Resonance Imaging for Delineating Malignant Intraprostatic Lesions

    SciTech Connect

    Chang, Joe H.; Lim Joon, Daryl; Davis, Ian D.; Lee, Sze Ting; Hiew, Chee-Yan; Esler, Stephen; Gong, Sylvia J.; Wada, Morikatsu; Clouston, David; O'Sullivan, Richard; Goh, Yin P.; Bolton, Damien; Scott, Andrew M.; Khoo, Vincent

    2015-06-01

    Purpose: The purpose of this study was to compare the accuracy of [{sup 11}C]choline positron emission tomography (CHOL-PET) with that of the combination of T2-weighted and diffusion-weighted (T2W/DW) magnetic resonance imaging (MRI) for delineating malignant intraprostatic lesions (IPLs) for guiding focal therapies and to investigate factors predicting the accuracy of CHOL-PET. Methods and Materials: This study included 21 patients who underwent CHOL-PET and T2W/DW MRI prior to radical prostatectomy. Two observers manually delineated IPL contours for each scan, and automatic IPL contours were generated on CHOL-PET based on varying proportions of the maximum standardized uptake value (SUV). IPLs identified on prostatectomy specimens defined reference standard contours. The imaging-based contours were compared with the reference standard contours using Dice similarity coefficient (DSC), and sensitivity and specificity values. Factors that could potentially predict the DSC of the best contouring method were analyzed using linear models. Results: The best automatic contouring method, 60% of the maximum SUV (SUV{sub 60}) , had similar correlations (DSC: 0.59) with the manual PET contours (DSC: 0.52, P=.127) and significantly better correlations than the manual MRI contours (DSC: 0.37, P<.001). The sensitivity and specificity values were 72% and 71% for SUV{sub 60}; 53% and 86% for PET manual contouring; and 28% and 92% for MRI manual contouring. The tumor volume and transition zone pattern could independently predict the accuracy of CHOL-PET. Conclusions: CHOL-PET is superior to the combination of T2W/DW MRI for delineating IPLs. The accuracy of CHOL-PET is insufficient for gland-sparing focal therapies but may be accurate enough for focal boost therapies. The transition zone pattern is a new classification that may predict how well CHOL-PET delineates IPLs.

  16. Added value of diffusion-weighted MRI in detection of cervical cancer recurrence: comparison with morphologic and dynamic contrast-enhanced MRI sequences

    PubMed Central

    Lucas, Rita; Dias, João Lopes; Cunha, Teresa Margarida

    2015-01-01

    PURPOSE We aimed to evaluate the added value of diffusion-weighted imaging (DWI) to standard magnetic resonance imaging (MRI) for detecting post-treatment cervical cancer recurrence. The detection accuracy of T2-weighted (T2W) images was compared with that of T2W MRI combined with either dynamic contrast-enhanced (DCE) MRI or DWI. METHODS Thirty-eight women with clinically suspected uterine cervical cancer recurrence more than six months after treatment completion were examined with 1.5 Tesla MRI including T2W, DCE, and DWI sequences. Disease was confirmed histologically and correlated with MRI findings. The diagnostic performance of T2W imaging and its combination with either DCE or DWI were analyzed. Sensitivity, positive predictive value, and accuracy were calculated. RESULTS Thirty-six women had histologically proven recurrence. The accuracy for recurrence detection was 80% with T2W/DCE MRI and 92.1% with T2W/DWI. The addition of DCE sequences did not significantly improve the diagnostic ability of T2W imaging, and this sequence combination misclassified two patients as falsely positive and seven as falsely negative. The T2W/DWI combination revealed a positive predictive value of 100% and only three false negatives. CONCLUSION The addition of DWI to T2W sequences considerably improved the diagnostic ability of MRI. Our results support the inclusion of DWI in the initial MRI protocol for the detection of cervical cancer recurrence, leaving DCE sequences as an option for uncertain cases. PMID:26200480

  17. Improving background suppression in diffusion-weighted imaging of the abdomen and pelvis using STIR with single-axis diffusion encoding.

    PubMed

    Kwee, Thomas C; Takahara, Taro; Niwa, Tetsu; Yamashita, Tomohiro; Van Cauteren, Marc; Nievelstein, Rutger A J; Luijten, Peter R

    2011-07-01

    Bowel contents and peripheral nerves often show high signal intensity at diffusion-weighted imaging (DWI) of the abdomen and pelvis, obscuring or mimicking pathology. This study introduced and compared short tau inversion recovery (STIR) with single-axis DWI to the usual combination of spectral fat suppression (SFS) with trace DWI in the suppression of bowel contents and peripheral nerves. Five volunteers underwent both STIR with single-axis DWI and SFS with trace DWI of the abdomen and pelvis. Images were evaluated by two observers with respect to the suppression of signal of bowel contents and peripheral nerves using four-point grading scales (4=poor suppression; 3=moderate suppression; 2=good suppression; 1=excellent suppression). Mean scores (±S.D.) regarding the suppression of bowel contents were 1.60±0.55 and 1.40±0.89 for STIR with single-axis DWI and 3.40±0.55 and 3.00±1.00 for SFS with trace DWI for observers 1 and 2, respectively. Mean scores regarding the suppression of peripheral nerves were 1.20±0.45 and 1.20±0.45 for STIR with single-axis DWI and 2.40±0.89 and 2.80±0.84 for SFS with trace DWI for observers 1 and 2, respectively. In conclusion, STIR with single-axis DWI is superior to SFS with trace DWI in the suppression of bowel signal and peripheral nerves. PMID:21546187

  18. Diagnostic performance of diffusion-weighted MRI for detection of pelvic metastatic lymph nodes in patients with cervical cancer: a systematic review and meta-analysis

    PubMed Central

    Shen, G; Zhou, H; Deng, H

    2015-01-01

    In recent years, diffusion-weighted (DW) MRI has emerged as a new technique for detecting the pelvic lymph metastases in patients with cervical cancer. The aim of this meta-analysis was to assess the diagnostic value of DW imaging (DWI) for benign/malignant discrimination of pelvic lymph nodes (LNs). Studies about DWI for the detection of metastatic LNs were searched in the PubMed, EMBASE, Web of Science, EBSCO, the Cochrane Library and three Chinese databases. Based on the extracted data, we determined pooled sensitivities, specificities and diagnostic odds ratios (DORs) across studies, calculated positive and negative likelihood ratios (LRs) and constructed summary receiver operating characteristic curves with area under the curve (AUC) and Q* obtained. We also analysed the heterogeneity between studies based on subgroup analysis, threshold effect and publication bias. In total, 15 studies involving 1021 patients met the inclusion criteria. The pooled sensitivity, specificity and DOR of DWI were 0.86 [95% confidence interval (CI), 0.84–0.89], 0.84 (95% CI, 0.83–0.86) and 47.21 (95% CI, 25.67–86.81), respectively. LR syntheses yielded overall positive LR of 6.55 (95% CI, 4.77–9.01) and negative LR of 0.17 (95% CI, 0.12–0.23). The AUC and Q* index were 0.9384 and 0.8754, respectively. The heterogeneity was relatively high between studies; however, there was no evidence for threshold effect and publication bias. DWI is beneficial in the pelvic nodal assessment in patients with cervical cancer. Large-scale, high-quality trials with standard protocols are required to evaluate its clinical value for discrimination of metastatic from non-metastatic pelvic LNs in patients with cervical cancer. Advances in knowledge include providing evidence to assess the role of DWI in nodal staging of cervical cancer. PMID:26111112

  19. Diagnostic performance of diffusion-weighted MRI for detection of pelvic metastatic lymph nodes in patients with cervical cancer: a systematic review and meta-analysis.

    PubMed

    Shen, G; Zhou, H; Jia, Z; Deng, H

    2015-08-01

    In recent years, diffusion-weighted (DW) MRI has emerged as a new technique for detecting the pelvic lymph metastases in patients with cervical cancer. The aim of this meta-analysis was to assess the diagnostic value of DW imaging (DWI) for benign/malignant discrimination of pelvic lymph nodes (LNs). Studies about DWI for the detection of metastatic LNs were searched in the PubMed, EMBASE, Web of Science, EBSCO, the Cochrane Library and three Chinese databases. Based on the extracted data, we determined pooled sensitivities, specificities and diagnostic odds ratios (DORs) across studies, calculated positive and negative likelihood ratios (LRs) and constructed summary receiver operating characteristic curves with area under the curve (AUC) and Q* obtained. We also analysed the heterogeneity between studies based on subgroup analysis, threshold effect and publication bias. In total, 15 studies involving 1021 patients met the inclusion criteria. The pooled sensitivity, specificity and DOR of DWI were 0.86 [95% confidence interval (CI), 0.84-0.89], 0.84 (95% CI, 0.83-0.86) and 47.21 (95% CI, 25.67-86.81), respectively. LR syntheses yielded overall positive LR of 6.55 (95% CI, 4.77-9.01) and negative LR of 0.17 (95% CI, 0.12-0.23). The AUC and Q* index were 0.9384 and 0.8754, respectively. The heterogeneity was relatively high between studies; however, there was no evidence for threshold effect and publication bias. DWI is beneficial in the pelvic nodal assessment in patients with cervical cancer. Large-scale, high-quality trials with standard protocols are required to evaluate its clinical value for discrimination of metastatic from non-metastatic pelvic LNs in patients with cervical cancer. Advances in knowledge include providing evidence to assess the role of DWI in nodal staging of cervical cancer. PMID:26111112

  20. Evaluation of Cranial and Cervical Arteries and Brain Tissue in Transient Ischemic Attack Patients with Magnetic Resonance Angiography and Diffusion-Weighted Imaging

    PubMed Central

    Li, Jian-Long; Li, Chang-Shan; Fu, Jun-Hua; Zhang, Ke; Xu, Rui; Xu, Wen-Jian

    2015-01-01

    Background Magnetic resonance angiography (MRA) and diffusion-weighted imaging (DWI) have been widely used in the prediction of ischemic stroke; however, the differences of the 2 methods in detection the artery lesion differences between transient ischemic attack (TIA) and infarction patients have been long neglected. We performed the present study to investigate the differences between vessel characteristics detected by MRA and DWI in acute stroke and TIA patients. Material/Methods We classified 110 subjects into 2 groups and all the patients underwent both MRA and DWI. The degree of stenosis of cranial and cervical arteries, the distribution of the stenosis, the development and changes of the vessels, and the DWI scanning results of the brain tissue were all analyzed. Results We detected a significant difference in the number and the degree of stenosis of cranial and cervical arteries among the 3 groups (P=0.006). Compared with health controls, patients with TIA and cerebral infraction had much more severe stenosis and occlusive arteries (P<0.05). However, no significant difference was detected between TIA and cerebral infraction patients (P=0.148). Moreover, a higher rate of unilateral vertebral artery dysplasia was found in the vertebrobasilar TIA patients. Higher lesion signals were also observed by DWI in TIA patients of internal carotid artery system (4/8, 50%). Conclusions Vessel characteristics were not significantly different between TIA and infarction patients. Unilateral vertebral artery hypoplasia was a predisposing factor for vertebrobasilar TIA and ischemic focus in DWI detection was always caused by severe artery lesions. PMID:26073092

  1. Joint correction of Nyquist artifact and minuscule motion-induced aliasing artifact in interleaved diffusion weighted EPI data using a composite two-dimensional phase correction procedure.

    PubMed

    Chang, Hing-Chiu; Chen, Nan-Kuei

    2016-09-01

    Diffusion-weighted imaging (DWI) obtained with interleaved echo-planar imaging (EPI) pulse sequence has great potential of characterizing brain tissue properties at high spatial-resolution. However, interleaved EPI based DWI data may be corrupted by various types of aliasing artifacts. First, inconsistencies in k-space data obtained with opposite readout gradient polarities result in Nyquist artifact, which is usually reduced with 1D phase correction in post-processing. When there exist eddy current cross terms (e.g., in oblique-plane EPI), 2D phase correction is needed to effectively reduce Nyquist artifact. Second, minuscule motion induced phase inconsistencies in interleaved DWI scans result in image-domain aliasing artifact, which can be removed with reconstruction procedures that take shot-to-shot phase variations into consideration. In existing interleaved DWI reconstruction procedures, Nyquist artifact and minuscule motion-induced aliasing artifact are typically removed subsequently in two stages. Although the two-stage phase correction generally performs well for non-oblique plane EPI data obtained from well-calibrated system, the residual artifacts may still be pronounced in oblique-plane EPI data or when there exist eddy current cross terms. To address this challenge, here we report a new composite 2D phase correction procedure, which effective removes Nyquist artifact and minuscule motion induced aliasing artifact jointly in a single step. Our experimental results demonstrate that the new 2D phase correction method can much more effectively reduce artifacts in interleaved EPI based DWI data as compared with the existing two-stage artifact correction procedures. The new method robustly enables high-resolution DWI, and should prove highly valuable for clinical uses and research studies of DWI. PMID:27114342

  2. Penrose inequality and apparent horizons

    SciTech Connect

    Ben-Dov, Ishai

    2004-12-15

    A spherically symmetric spacetime is presented with an initial data set that is asymptotically flat, satisfies the dominant energy condition, and such that on this initial data M<{radical}(A/16{pi}), where M is the total mass and A is the area of the apparent horizon. This provides a counterexample to a commonly stated version of the Penrose inequality, though it does not contradict the true Penrose inequality.

  3. Silent cerebral infarct after cardiac catheterization as detected by diffusion weighted Magnetic Resonance Imaging: a randomized comparison of radial and femoral arterial approaches

    PubMed Central

    Hamon, Michèle; Burzotta, Francesco; Oppenheim, Catherine; Morello, Rémy; Viader, Fausto; Hamon, Martial

    2007-01-01

    Background and objective Cerebral microembolism detected by transcranial Doppler (TCD) occurs systematically during cardiac catheterization, but its clinical relevance, remains unknown. Studies suggest that asymptomatic embolic cerebral infarction detectable by diffusion-weighted (DW) MRI might exist after percutaneous cardiac interventions with a frequency as high as 15 to 22% of cases. We have set up, for the first time, a prospective multicenter trial to assess the rate of silent cerebral infarction after cardiac catheterization and to compare the impact of the arterial access site, comparing radial and femoral access, on this phenomenon. Study design This prospective study will be performed in patients with severe aortic valve stenosis. To assess the occurrence of cerebral infarction, all patients will undergo cerebral DW-MRI and neurological assessment within 24 hours before, and 48 hours after cardiac catheterization and retrograde catheterization of the aortic valve. Randomization for the access site will be performed before coronary angiography. A subgroup will be monitored by transcranial power M-mode Doppler during cardiac catheterization to observe cerebral blood flow and track emboli. Neuropsychological tests will also be recorded in a subgroup of patients before and after the interventional procedures to assess the impact of silent brain injury on potential cognitive decline. The primary end-point of the study is a direct comparison of ischemic cerebral lesions as detected by serial cerebral DW-MRI between patients explored by radial access and patients explored by femoral access. Secondary end-points include comparison of neuropsychological test performance and number of microembolism signals observed in the two groups. Implications Using serial DW-MRI, silent cerebral infarction rate will be defined and the potential influence of vascular access site will be evaluated. Silent cerebral infarction might be a major concern during cardiac catheterization

  4. Volume of Bone Metastasis Assessed with Whole-Body Diffusion-weighted Imaging Is Associated with Overall Survival in Metastatic Castration-resistant Prostate Cancer.

    PubMed

    Perez-Lopez, Raquel; Lorente, David; Blackledge, Matthew D; Collins, David J; Mateo, Joaquin; Bianchini, Diletta; Omlin, Aurelius; Zivi, Andrea; Leach, Martin O; de Bono, Johann S; Koh, Dow-Mu; Tunariu, Nina

    2016-07-01

    Purpose To determine the correlation between the volume of bone metastasis as assessed with diffusion-weighted (DW) imaging and established prognostic factors in metastatic castration-resistant prostate cancer (mCRPC) and the association with overall survival (OS). Materials and Methods This retrospective study was approved by the institutional review board; informed consent was obtained from all patients. The authors analyzed whole-body DW images obtained between June 2010 and February 2013 in 53 patients with mCRPC at the time of starting a new line of anticancer therapy. Bone metastases were identified and delineated on whole-body DW images in 43 eligible patients. Total tumor diffusion volume (tDV) was correlated with the bone scan index (BSI) and other prognostic factors by using the Pearson correlation coefficient (r). Survival analysis was performed with Kaplan-Meier analysis and Cox regression. Results The median tDV was 503.1 mL (range, 5.6-2242 mL), and the median OS was 12.9 months (95% confidence interval [CI]: 8.7, 16.1 months). There was a significant correlation between tDV and established prognostic factors, including hemoglobin level (r = -0.521, P < .001), prostate-specific antigen level (r = 0.556, P < .001), lactate dehydrogenase level (r = 0.534, P < .001), alkaline phosphatase level (r = 0.572, P < .001), circulating tumor cell count (r = 0.613, P = .004), and BSI (r = 0.565, P = .001). A higher tDV also showed a significant association with poorer OS (hazard ratio, 1.74; 95% CI: 1.02, 2.96; P = .035). Conclusion Metastatic bone disease from mCRPC can be evaluated and quantified with whole-body DW imaging. Whole-body DW imaging-generated tDV showed correlation with established prognostic biomarkers and is associated with OS in mCRPC. (©) RSNA, 2016 Online supplemental material is available for this article. PMID:26807894

  5. Evaluation of a Simplified Intravoxel Incoherent Motion (IVIM) Analysis of Diffusion-Weighted Imaging for Prediction of Tumor Size Changes and Imaging Response in Breast Cancer Liver Metastases Undergoing Radioembolization: A Retrospective Single Center Analysis.

    PubMed

    Pieper, Claus C; Sprinkart, Alois M; Meyer, Carsten; König, Roy; Schild, Hans H; Kukuk, Guido M; Mürtz, Petra

    2016-04-01

    To investigate the value of a simplified intravoxel incoherent motion (IVIM) analysis for evaluation of therapy-induced tumor changes and response of breast cancer liver metastases (mBRC) undergoing radioembolization.In 21 females (mean age 54 years, range 43-72) with mBRC tumor size changes and response evaluation criteria in solid tumors (RECIST) response to 26 primary radioembolization procedures were analyzed. Standard 1.5-T liver magnetic resonance imaging including respiratory-gated diffusion-weighted imaging (DWI) with b0 = 0 s/mm, b1 = 50 s/mm, b2 = 800 s/mm before and 6 weeks after each treatment was performed. In addition to the apparent diffusion coefficient (ADC)(0,800), the estimated diffusion coefficient D' and the perfusion fraction f' were determined using a simplified IVIM approach. For each radioembolization, the 2 largest treated metastases (if available) were analyzed. Lesions were categorized according to size changes into group A (reduction of longest diameter [LD]) and group B (LD increase) after 3 months. Radioembolization procedures were further categorized into "response" (partial response and stable disease) and "nonresponse" (progressive disease) according to RECIST after 3 months. ADC and D' are given in 10 mm/s.Forty-five metastases were analyzed. Thirty-two lesions were categorized as A; 13 as B. Before therapy, group A lesions showed significantly larger f'-values than B (P = 0.001), but ADC(0,800) and D' did not differ. After therapy, in group A lesions the ADC(0,800)- and D'-values increased and f' decreased (P < 0.0001); in contrast in group B lesions f' increased (P = 0.001). Groups could be differentiated by preinterventional f' and by changes of D' and f' between pre and postinterventional imaging (area under the curve [AUC] of 0.903, 0.747 and 1.0, respectively).Preinterventional parameters did not differ between responders and nonresponders according to RECIST. ADC(0,800)- and D'-values showed a

  6. Evaluation of a Simplified Intravoxel Incoherent Motion (IVIM) Analysis of Diffusion-Weighted Imaging for Prediction of Tumor Size Changes and Imaging Response in Breast Cancer Liver Metastases Undergoing Radioembolization

    PubMed Central

    Pieper, Claus C.; Sprinkart, Alois M.; Meyer, Carsten; König, Roy; Schild, Hans H.; Kukuk, Guido M.; Mürtz, Petra

    2016-01-01

    Abstract To investigate the value of a simplified intravoxel incoherent motion (IVIM) analysis for evaluation of therapy-induced tumor changes and response of breast cancer liver metastases (mBRC) undergoing radioembolization. In 21 females (mean age 54 years, range 43–72) with mBRC tumor size changes and response evaluation criteria in solid tumors (RECIST) response to 26 primary radioembolization procedures were analyzed. Standard 1.5-T liver magnetic resonance imaging including respiratory-gated diffusion-weighted imaging (DWI) with b0 = 0 s/mm2, b1 = 50 s/mm2, b2 = 800 s/mm2 before and 6 weeks after each treatment was performed. In addition to the apparent diffusion coefficient (ADC)(0,800), the estimated diffusion coefficient D′ and the perfusion fraction f′ were determined using a simplified IVIM approach. For each radioembolization, the 2 largest treated metastases (if available) were analyzed. Lesions were categorized according to size changes into group A (reduction of longest diameter [LD]) and group B (LD increase) after 3 months. Radioembolization procedures were further categorized into “response” (partial response and stable disease) and “nonresponse” (progressive disease) according to RECIST after 3 months. ADC and D′ are given in 10−6 mm2/s. Forty-five metastases were analyzed. Thirty-two lesions were categorized as A; 13 as B. Before therapy, group A lesions showed significantly larger f′-values than B (P = 0.001), but ADC(0,800) and D′ did not differ. After therapy, in group A lesions the ADC(0,800)- and D′-values increased and f′ decreased (P < 0.0001); in contrast in group B lesions f′ increased (P = 0.001). Groups could be differentiated by preinterventional f′ and by changes of D′ and f′ between pre and postinterventional imaging (area under the curve [AUC] of 0.903, 0.747 and 1.0, respectively). Preinterventional parameters did not differ between responders and nonresponders

  7. Analysis of spatiotemporal variation in b-value for the Sunda arc using high precision earthquake location

    NASA Astrophysics Data System (ADS)

    Nugraha, Andri Dian; Shiddiqi, Hasbi Ash; Widiyantoro, Sri; Sutiyono, Handayani, Titi

    2016-05-01

    The Sunda arc is one of the most active tectonic regions, which has a complex tectonic setting due to different tectonic regimes and subduction geometry along this arc. We analyzed variation in b-value for this region in order to obtain better information regarding the state of stress in this region. For the first step, we relocated earthquake hypocenters taken from the BMKG catalog for the period 2009 - 2015 by employing a teleseismic double-difference (DD) relocation method and using a 3D velocity model. There are 10,440 earthquakes that were successfully relocated with greatly reduced residual errors. Based on its tectonic feature and earthquake distribution, we divided the study area into 8 regions, i.e. northern Sumatra, central Sumatra, southern Sumatra, Sunda strait, western Java, eastern Java, lesser Sunda islands, and Sunda-Banda transition zone. For b-value analysis we combined the BMKG catalog with the International Seismological Centre (ISC) catalog from 2006 to 2009 to obtain a longer time period. We analyzed the spatial variation in b-value for western sunda arc and found a low b-value that matches well with earthquake locations.

  8. In Acute Stroke, Can CT Perfusion-Derived Cerebral Blood Volume Maps Substitute for Diffusion-Weighted Imaging in Identifying the Ischemic Core?

    PubMed Central

    Copen, William A.; Morais, Livia T.; Wu, Ona; Schwamm, Lee H.; Schaefer, Pamela W.; González, R. Gilberto; Yoo, Albert J.

    2015-01-01

    Background and Purpose In the treatment of patients with suspected acute ischemic stroke, increasing evidence suggests the importance of measuring the volume of the irreversibly injured “ischemic core.” The gold standard method for doing this in the clinical setting is diffusion-weighted magnetic resonance imaging (DWI), but many authors suggest that maps of regional cerebral blood volume (CBV) derived from computed tomography perfusion imaging (CTP) can substitute for DWI. We sought to determine whether DWI and CTP-derived CBV maps are equivalent in measuring core volume. Methods 58 patients with suspected stroke underwent CTP and DWI within 6 hours of symptom onset. We measured low-CBV lesion volumes using three methods: “objective absolute,” i.e. the volume of tissue with CBV below each of six published absolute thresholds (0.9–2.5 mL/100 g), “objective relative,” whose six thresholds (51%-60%) were fractions of mean contralateral CBV, and “subjective,” in which two radiologists (R1, R2) outlined lesions subjectively. We assessed the sensitivity and specificity of each method, threshold, and radiologist in detecting infarction, and the degree to which each over- or underestimated the DWI core volume. Additionally, in the subset of 32 patients for whom follow-up CT or MRI was available, we measured the proportion of CBV- or DWI-defined core lesions that exceeded the follow-up infarct volume, and the maximum amount by which this occurred. Results DWI was positive in 72% (42/58) of patients. CBV maps’ sensitivity/specificity in identifying DWI-positive patients were 100%/0% for both objective methods with all thresholds, 43%/94% for R1, and 83%/44% for R2. Mean core overestimation was 156–699 mL for objective absolute thresholds, and 127–200 mL for objective relative thresholds. For R1 and R2, respectively, mean±SD subjective overestimation were -11±26 mL and -11±23 mL, but subjective volumes differed from DWI volumes by up to 117 and 124

  9. 3D Crustal Structure and 3D-b-value in AbuDabbab Seismogenic Source, Northern Red Sea.

    NASA Astrophysics Data System (ADS)

    Al-Arifi, Nassir; El Kherpy, Sami; Koulakov, Ivan

    2014-05-01

    Abu Dabbab seismogenic source region is of unique seismic activity located on the Egyptian Red Sea coast. It's known as earthquake Cannons where the earthquakes are accompanied by a sound of distinct rumbling similar to the sound of a distant quarry blast which is heard by humans for several generations. Seismic activity of Abu Dabbab becomes very well determined after establishing of the Egyptian National Seismic Network 1997. Joint earthquake tomography inversion of local and regional data has been performed in order to image the crustal heterogeneity and the origin of the cannons earthquakes. Most previous studies suggested that this activity is of magmatic origin. We found the seismicity forms an arc shaped cluster that surrounds an aseismic block. This aseismic block has high velocities and a low Vp/Vs ratio. The origin of this seismic activity is probably due an active fault below the non-deformed block of Precambrian Igneous rock reaching a depth of ~10 km. Spatial mapping of the frequency magnitude distribution of the earthquakes and 3D-b-value indicate a strong variation moreover high b-value (1.4) at depth downward the rigid block. The Combined interpretation of the seismic imaging and 3D b-value in addition to the seismological and the geophysical observations revealed the tectonic origin of the earthquake activity in this area which is related strongly to the evolution of the crust in the Red Sea and its tectonic activity. KEYWARD:Three dimensional Crustal Structure - Seismic activity -Three-D b-value- Red Sea tectonics- Tectonic activity

  10. Data-driven spatial b value estimation with applications to California seismicity: To b or not to b

    NASA Astrophysics Data System (ADS)

    Kamer, Yavor; Hiemer, Stefan

    2015-07-01

    In this paper we present a penalized likelihood-based method for spatial estimation of Gutenberg-Richter's b value. Our method incorporates a nonarbitrary partitioning scheme based on Voronoi tessellation, which allows for the optimal partitioning of space using a minimum number of free parameters. By random placement of an increasing number of Voronoi nodes, we are able to explore the whole solution space in terms of model complexity. We obtain an overall likelihood for each model by estimating the b values in all Voronoi regions and calculating its joint likelihood using Aki's formula. Accounting for the number of free parameters, we then calculate the Bayesian Information Criterion for all random realizations. We investigate the ensemble of the best performing models and demonstrate the robustness and validity of our method through extensive synthetic tests. We apply our method to the seismicity of California using two different time spans of the Advanced National Seismic System catalog (1984-2014 and 2004-2014). The results show that for the last decade, the b value variation in the well-instrumented parts of mainland California is limited to the range of (0.94 ± 0.04-1.15 ± 0.06). Apart from the Geysers region, the observed variation can be explained by network-related discrepancies in the magnitude estimations. Our results suggest that previously reported spatial b value variations obtained using classical fixed radius or nearest neighbor methods are likely to have been overestimated, mainly due to subjective parameter choices. We envision that the likelihood-based model selection criteria used in this study can be a useful tool for generating improved earthquake forecasting models.

  11. Microseismicity and b-values of the Wabash Valley Intraplate Seismic Zone from short-period phased arrays

    NASA Astrophysics Data System (ADS)

    Conder, J. A.; Milliron, K.; Zhu, L.

    2014-12-01

    Two phased arrays of 9 short-period stations each are currently recording in the Wabash Valley Seismic Zone (WVSZ) as part of the EarthScope Wabash FlexArray project. The phased arrays aim to address the level of microseismicity produced by the intraplate seismic zone. Although seismic hazard maps of the U.S. Midwest are dominated by the New Madrid Seismic Zone (NMSZ), the WVSZ has released 40% more seismic energy than the NMSZ over the last half century with four events larger than M5 and only one in the NMSZ reaching that threshold. A comparison of event frequency statistics suggests two markedly different systems. The NMSZ exhibits b-values near unity, but the WVSZ exhibits much smaller b-values in the 0.6-0.7 range. Deviations less than unity may be controlled through crack geometry and/or greater shear stresses possibly indicating a time-dependent, or migrating, behavior in mid-continent. Alternatively, it may be the case that the low b-values are simply a reflection of less complete catalog than the NMSZ. A previous short-term microseismicity study of the WVSZ shows a dearth of non-anthropogenic sources in the Wabash. The phased array near the central portion of the WVSZ largely confirms the previously noted lack of substantial natural seismicity along the central portion of the fault system and the associated low b-values. However, the phased array near the southern termination of the fault system shows significantly more activity. Importantly, the largest events from the Wabash, including the 2008 M5.4 Mt. Carmel and the 1968 M5.5 Harrisburg events occurred near the northern and southern ends of the fault system. The phased arrays seem to indicate different portions of the fault system yielding different levels of activity. As the catalogs become more complete, there is a preliminary suggestion that the anomalously low b-values for the Wabash do not denote a system under significantly larger stresses, but rather a conflation of regions along-strike of the

  12. Advanced MRI increases the diagnostic accuracy of recurrent glioblastoma: Single institution thresholds and validation of MR spectroscopy and diffusion weighted MR imaging.

    PubMed

    Kazda, Tomas; Bulik, Martin; Pospisil, Petr; Lakomy, Radek; Smrcka, Martin; Slampa, Pavel; Jancalek, Radim

    2016-01-01

    The accurate identification of glioblastoma progression remains an unmet clinical need. The aim of this prospective single-institutional study is to determine and validate thresholds for the main metabolite concentrations obtained by MR spectroscopy (MRS) and the values of the apparent diffusion coefficient (ADC) to enable distinguishing tumor recurrence from pseudoprogression. Thirty-nine patients after the standard treatment of a glioblastoma underwent advanced imaging by MRS and ADC at the time of suspected recurrence - median time to progression was 6.7 months. The highest significant sensitivity and specificity to call the glioblastoma recurrence was observed for the total choline (tCho) to total N-acetylaspartate (tNAA) concentration ratio with the threshold ≥ 1.3 (sensitivity 100.0% and specificity 94.7%). The ADCmean value higher than 1313 × 10(- 6) mm(2)/s was associated with the pseudoprogression (sensitivity 98.3%, specificity 100.0%). The combination of MRS focused on the tCho/tNAA concentration ratio and the ADCmean value represents imaging methods applicable to early non-invasive differentiation between a glioblastoma recurrence and a pseudoprogression. However, the institutional definition and validation of thresholds for differential diagnostics is needed for the elimination of setup errors before implementation of these multimodal imaging techniques into clinical practice, as well as into clinical trials. PMID:27298760

  13. Selective neuronal vulnerability of human hippocampal CA1 neurons: lesion evolution, temporal course, and pattern of hippocampal damage in diffusion-weighted MR imaging.

    PubMed

    Bartsch, Thorsten; Döhring, Juliane; Reuter, Sigrid; Finke, Carsten; Rohr, Axel; Brauer, Henriette; Deuschl, Günther; Jansen, Olav

    2015-11-01

    The CA1 (cornu ammonis) region of hippocampus is selectively vulnerable to a variety of metabolic and cytotoxic insults, which is mirrored in a delayed neuronal death of CA1 neurons. The basis and mechanisms of this regional susceptibility of CA1 neurons are poorly understood, and the correlates in human diseases affecting the hippocampus are not clear. Adopting a translational approach, the lesion evolution, temporal course, pattern of diffusion changes, and damage in hippocampal CA1 in acute neurologic disorders were studied using high-resolution magnetic resonance imaging. In patients with hippocampal ischemia (n=50), limbic encephalitis (n=30), after status epilepticus (n=17), and transient global amnesia (n=53), the CA1 region was selectively affected compared with other CA regions of the hippocampus. CA1 neurons exhibited a maximum decrease of apparent diffusion coefficient (ADC) 48 to 72 hours after the insult, irrespective of the nature of the insult. Hypoxic-ischemic insults led to a significant lower ADC suggesting that the ischemic insult results in a stronger impairment of cellular metabolism. The evolution of diffusion changes show that CA1 diffusion lesions mirror the delayed time course of the pathophysiologic cascade typically observed in animal models. Studying the imaging correlates of hippocampal damage in humans provides valuable insight into the pathophysiology and neurobiology of the hippocampus. PMID:26082014

  14. Efficacy of diffusion-weighted magnetic resonance imaging in follow-up patients treated with open partial cystectomy of liver hydatid cysts

    PubMed Central

    Karakas, Ekrem; Uzunköy, Ali; Karakas, Emel Yigit; Gundogan, Mehmet; Karakas, Omer; Boyaci, Fatıma Nurefsan; Seker, Ahmet; Ulas, Turgay; Cece, Hasan; Ozgonul, Abdullah; Cevik, Muazzez; Yucel, Yusuf

    2014-01-01

    Background and Objective: The aim of this study was to evaluate the efficacy of DWI in differentiation of patients with residual cavity and type 1 hydatid cyst (HC) in the liver. Methods: 32 patients were included. 12 of these patients had type 1 HC and the remainders (n = 20) had postoperative residual cavities. In all patients, axial T2-weighted and DWI images were obtained. An apparent diffusion coefficient (ADC) map of the images was automatically generated and the ADC values were measured on this map for all patients. Mann-Whitney U test was used for comparison of continuous variables between two groups. Results: The mean diameters of type 1 hydatid cyst and residual cavity groups were 83.42 mm, 49.30 mm, respectively (P = 0.001). There were no significant differences in gender and age between the groups (both P > 0.05). The mean ADC values of type 1 hydatid cyst and residual cavity groups were 2.58 ± 0.13 × 10-3 s/mm2, 2.58 ± 0.16 × 10-3 s/mm2, respectively (P = 0.953). Conclusion: DWI might not be suitable to differentiate the postoperative residual cavity from the type 1 hydatid cyst in the liver due to similarity of ADC values between postoperative residual cavity and type 1 hydatid cyst. PMID:25664009

  15. Differentiation of Benign Angiomatous and Microcystic Meningiomas with Extensive Peritumoral Edema from High Grade Meningiomas with Aid of Diffusion Weighted MRI

    PubMed Central

    Azizyan, Avetis; Eboli, Paula; Drazin, Doniel; Mirocha, James; Maya, Marcel M.; Bannykh, Serguei

    2014-01-01

    Objective. To determine whether angiomatous and microcystic meningiomas which mimic high grade meningiomas based on extent of peritumoral edema can be reliably differentiated as low grade tumors using normalized apparent diffusion coefficient (ADC) values. Methods. Preoperative magnetic resonance imaging (MRI) of seventy patients with meningiomas was reviewed. Morphologically, the tumors were divided into 3 groups. Group 1 contained 12 pure microcystic, 3 pure angiomatoid and 7 mixed angiomatoid and microcystic tumors. Group 2 included World Health Organization (WHO) grade II and WHO grade III tumors, of which 28 were atypical and 9 were anaplastic meningiomas. Group 3 included WHO grade I tumors of morphology different than angiomatoid and microcystic. Peritumoral edema, normalized ADC, and cerebral blood volume (CBV) were obtained for all meningiomas. Results. Edema index of tumors in group 1 and group 2 was significantly higher than in group 3. Normalized ADC value in group 1 was higher than in group 2, but not statistically significant between groups 1 and 3. CBV values showed no significant group differences. Conclusion. A combination of peritumoral edema index and normalized ADC value is a novel approach to preoperative differentiation between true aggressive meningiomas and mimickers such as angiomatous and microcystic meningiomas. PMID:25478572

  16. ≤ 1 Mining-Induced Earthquakes Around a Mining Front and b Value Invariance with Post-Blast Time

    NASA Astrophysics Data System (ADS)

    Naoi, Makoto; Nakatani, Masao; Horiuchi, Shigeki; Yabe, Yasuo; Philipp, Joachim; Kgarume, Thabang; Morema, Gilbert; Khambule, Sifiso; Masakale, Thabang; Ribeiro, Luiz; Miyakawa, Koji; Watanabe, Atsushi; Otsuki, Kenshiro; Moriya, Hirokazu; Murakami, Osamu; Kawakata, Hironori; Yoshimitsu, Nana; Ward, Anthony; Durrheim, Ray; Ogasawara, Hiroshi

    2014-10-01

    We investigated frequency-magnitude distribution (FMD) of acoustic emissions (AE) occurring near an active mining front in a South African gold mine, using a catalog developed from an AE network, which is capable of detecting AEs down to M W -5. When records of blasts were removed, FMDs of AEs obeyed a Gutenberg-Richter law with similar b values, not depending on post-blasting time from the initial 1-min interval through more than 30 h. This result denies a suggestion in a previous study ( Richardson and Jordan Bull Seismol Soc Am, 92:1766-1782, 2002) that new fractures generated by blasting disturb the size distribution of background events, which they interpreted as slip events on existing weak planes. Our AE catalog showed that the GR law with b ˜ 1.2 was valid between M W -3.7 and 0 for AEs around the mining front. Further, using the mine's seismic catalog, which covers a longer time period of the same area, we could extend the validity range of the GR law with the same b value up to M W 1.

  17. Prediction of Response to Concurrent Chemoradiotherapy with Temozolomide in Glioblastoma: Application of Immediate Post-Operative Dynamic Susceptibility Contrast and Diffusion-Weighted MR Imaging

    PubMed Central

    Lee, Eun Kyoung; Yun, Tae Jin; Kang, Koung Mi; Kim, Tae Min; Lee, Se-Hoon; Park, Chul-Kee; Park, Sung-Hye; Kim, Il Han

    2015-01-01

    Objective To determine whether histogram values of the normalized apparent diffusion coefficient (nADC) and normalized cerebral blood volume (nCBV) maps obtained in contrast-enhancing lesions detected on immediate post-operative MR imaging can be used to predict the patient response to concurrent chemoradiotherapy (CCRT) with temozolomide (TMZ). Materials and Methods Twenty-four patients with GBM who had shown measurable contrast enhancement on immediate post-operative MR imaging and had subsequently undergone CCRT with TMZ were retrospectively analyzed. The corresponding histogram parameters of nCBV and nADC maps for measurable contrast-enhancing lesions were calculated. Patient groups with progression (n = 11) and non-progression (n = 13) at one year after the operation were identified, and the histogram parameters were compared between the two groups. Receiver operating characteristic (ROC) analysis was used to determine the best cutoff value for predicting progression. Progression-free survival (PFS) was determined with the Kaplan-Meier method and the log-rank test. Results The 99th percentile of the cumulative nCBV histogram (nCBV C99) on immediate post-operative MR imaging was a significant predictor of one-year progression (p = 0.033). ROC analysis showed that the best cutoff value for predicting progression after CCRT was 5.537 (sensitivity and specificity were 72.7% and 76.9%, respectively). The patients with an nCBV C99 of < 5.537 had a significantly longer PFS than those with an nCBV C99 of ≥ 5.537 (p = 0.026). Conclusion The nCBV C99 from the cumulative histogram analysis of the nCBV from immediate post-operative MR imaging may be feasible for predicting glioblastoma response to CCRT with TMZ. PMID:26576125

  18. Diffusion-Weighted Imaging for Pretreatment Evaluation and Prediction of Treatment Effect in Patients Undergoing CT-Guided Injection for Lumbar Disc Herniation

    PubMed Central

    Niu, Xiang-Ke; Bhetuwal, Anup

    2015-01-01

    Objective To determine whether a change in apparent diffusion coefficient (ADC) value could predict early response to CT-guided Oxygen-Ozone (O2-O3) injection therapy in patients with unilateral mono-radiculopathy due to lumbar disc herniation. Materials and Methods A total of 52 patients with unilateral mono-radiculopathy received a single intradiscal (3 mL) and periganglionic (5 mL) injection of an O2-O3 mixture. An ADC index of the involved side to the intact side was calculated using the following formula: pre-treatment ADC index = ([ADC involved side - ADC intact side] / ADC intact side) × 100. We analyzed the relationship between the pre-treatment Oswestry Disability Index (ODI) and the ADC index. In addition, the correlation between ODI recovery ratio and ADC index was investigated. The sensitivity and specificity of the ADC index for predicting response in O2-O3 therapy was determined. Results Oswestry Disability Index and the ADC index was not significantly correlated (r = -0.125, p = 0.093). The ADC index and ODI recovery ratio was significantly correlated (r = 0.819, p < 0.001). When using 7.10 as the cut-off value, the ADC index obtained a sensitivity of 86.3% and a specificity of 82.9% for predicting successful response to therapy around the first month of follow-up. Conclusion This preliminary study demonstrates that the patients with decreased ADC index tend to show poor improvement of clinical symptoms. The ADC index may be a useful indicator to predict early response to CT-guided O2-O3 injection therapy in patients with unilateral mono-radiculopathy due to lumbar disc herniation. PMID:26175588

  19. Data for evaluation of fast kurtosis strategies, b-value optimization and exploration of diffusion MRI contrast.

    PubMed

    Hansen, Brian; Jespersen, Sune Nørhøj

    2016-01-01

    Here we describe and provide diffusion magnetic resonance imaging (dMRI) data that was acquired in neural tissue and a physical phantom. Data acquired in biological tissue includes: fixed rat brain (acquired at 9.4 T) and spinal cord (acquired at 16.4 T) and in normal human brain (acquired at 3 T). This data was recently used for evaluation of diffusion kurtosis imaging (DKI) contrasts and for comparison to diffusion tensor imaging (DTI) parameter contrast. The data has also been used to optimize b-values for ex vivo and in vivo fast kurtosis imaging. The remaining data was obtained in a physical phantom with three orthogonal fiber orientations (fresh asparagus stems) for exploration of the kurtosis fractional anisotropy. However, the data may have broader interest and, collectively, may form the basis for image contrast exploration and simulations based on a wide range of dMRI analysis strategies. PMID:27576023

  20. Data for evaluation of fast kurtosis strategies, b-value optimization and exploration of diffusion MRI contrast

    PubMed Central

    Hansen, Brian; Jespersen, Sune Nørhøj

    2016-01-01

    Here we describe and provide diffusion magnetic resonance imaging (dMRI) data that was acquired in neural tissue and a physical phantom. Data acquired in biological tissue includes: fixed rat brain (acquired at 9.4 T) and spinal cord (acquired at 16.4 T) and in normal human brain (acquired at 3 T). This data was recently used for evaluation of diffusion kurtosis imaging (DKI) contrasts and for comparison to diffusion tensor imaging (DTI) parameter contrast. The data has also been used to optimize b-values for ex vivo and in vivo fast kurtosis imaging. The remaining data was obtained in a physical phantom with three orthogonal fiber orientations (fresh asparagus stems) for exploration of the kurtosis fractional anisotropy. However, the data may have broader interest and, collectively, may form the basis for image contrast exploration and simulations based on a wide range of dMRI analysis strategies. PMID:27576023

  1. Relationship Between Choline and Apparent Diffusion Coefficient in Patients With Gliomas

    PubMed Central

    Khayal, Inas S.; Crawford, Forrest W.; Saraswathy, Suja; Lamborn, Kathleen R.; Chang, Susan M.; Cha, Soonmee; McKnight, Tracy R.; Nelson, Sarah J.

    2011-01-01

    Purpose To examine the relationship between apparent diffusion coefficients (ADC) from diffusion weighted imaging (DWI) and choline levels from proton magnetic resonance spectroscopic imaging (MRSI) in newly diagnosed Grade II and IV gliomas within distinct anatomic regions. Materials and Methods A total of 37 patients with Grade II and 28 patients with Grade IV glioma were scanned on a 1.5T system with 3D MRSI and DWI. Region level analysis included Spearman rank correlation between median normalized ADC and choline for each patient per grade within each distinct abnormal anatomical region. Voxel level analysis calculated a Spearman rank correlation per region, per patient. Results Grade II lesions showed no evidence of a correlation between normalized ADC and choline using either the region or voxel level analysis. Region level analysis of Grade IV lesions did not appear to correlate in the contrast enhancement or necrotic core, but did suggest a significant negative correlation in the more heterogeneous nonenhancing and combined regions. Conclusion There appears to be differences in the relationship between ADC and choline levels in Grade II and Grade IV gliomas. Correlation within these regions in Grade IV lesions was strongest when all regions were included, suggesting heterogeneity may be driving the relationship. PMID:18383265

  2. Fat Confounds the Observed Apparent Diffusion Coefficient in Patients with Hepatic Steatosis

    PubMed Central

    Hansmann, Jan; Hernando, Diego; Reeder, Scott B.

    2013-01-01

    Purpose Triglyceride signal contained in peaks near the water peak remain unsuppressed by conventional fat suppression techniques used in diffusion-weighted imaging (DWI). In this work we investigated the dependence of the apparent diffusion coefficient (ADC) on liver fat content and whether it is confounded by fat signal. Methods 43 patients underwent liver DWI (b=0,500s/mm2) and single-voxel MR-spectroscopy (MRS). Proton density fat-fraction (PDFF;range 0.23–34.5%) was measured from MRS. A theoretical model was developed to account for the effects of fat on observed ADC, and used to correct the ADC. Linear correlation analysis was performed to assess the relationship between PDFF and ADC before and after correction. Results Linear correlation analysis showed an inverse dependence between observed ADC and PDFF before correction (r2=0.132;p=0.017), and no dependence after correction (r2=0.033;p=0.24). Conclusion The observed decrease in ADC in patients with fatty liver is, at least in part, artifactual due to residual fat signal near the water peak. PMID:23161434

  3. Effect of imaging parameters on the accuracy of apparent diffusion coefficient and optimization strategies

    PubMed Central

    Celik, Azim

    2016-01-01

    PURPOSE We aimed to investigate the effect of key imaging parameters on the accuracy of apparent diffusion coefficient (ADC) maps using a phantom model combined with ADC calculation simulation and propose strategies to improve the accuracy of ADC quantification. METHODS Diffusion-weighted imaging (DWI) sequences were acquired on a phantom model using single-shot echo-planar imaging DWI at 1.5 T scanner by varying key imaging parameters including number of averages (NEX), repetition time (TR), echo time (TE), and diffusion preparation pulses. DWI signal simulations were performed for varying TR and TE. RESULTS Magnetic resonance diffusion signal and ADC maps were dependent on TR and TE imaging parameters as well as number of diffusion preparation pulses, but not on the NEX. However, the choice of a long TR and short TE could be used to minimize their effects on the resulting DWI sequences and ADC maps. CONCLUSION This study shows that TR and TE imaging parameters affect the diffusion images and ADC maps, but their effect can be minimized by utilizing diffusion preparation pulses. Another key imaging parameter, NEX, is less relevant to DWI and ADC quantification as long as DWI signal-to-noise ratio is above a certain level. Based on the phantom results and data simulations, DWI acquisition protocol can be optimized to obtain accurate ADC maps in routine clinical application for whole body imaging. PMID:26573977

  4. Spatial distribution of the b value under the Popocatepetl volcano and its relation with the structure of the magma chamber

    NASA Astrophysics Data System (ADS)

    Garza-Girón, R.; Zuniga, R. R.

    2014-12-01

    The spatial distribution of the b value under volcanoes and other tectonic environments is not uniform but it rather shows pockets of anomalies related to different phenomena. We analyzed the frequency-magnitude distribution of the 2191 best located volcano-tectonic events with MD ≥ 2.1 under the Popocatepetl volcano and performed 2D and 3D maps using a griding technique. For the 3D mapping we used samples of 100 events within spherical volumes with radii ≤ 3 km. Also, only volumes with σ ≤ 0.3 were taken into account. Three main anomalies with b ≥ 2.2 were detected within a normal crust (b ≤ 1.6). The first anomaly is observed north of the crater summit at depths 4-8 km and comprises a volume of approximately 15 km3. The second lies slightly to the E and SE of the crater at depths between 2 and 5 km, and the third and latter anomaly is located SE of the summit at depths of 6-12 km and spans over a volume of 40 km3 (or greater). In any case, we interpret our high b values anomalies as regions were high pore pressures (low effective stresses), high thermal gradients and/or high heterogeneity take place due to the presence of a magmatic body nearby. Whilst we cannot know with certainty if the source of the anomaly located N of the crater is a dyke complex or a shallow magma chamber, we infer that the shallowest volume mapped is related to Popocatepetl's plumbing system. The greatest anomalous volume located at the SE is thought to represent the main shallow magma chamber, since it is located at depths similar to those found in other volcanoes in the world and correlates with previous geophysical studies carried out at Popocatepetl.

  5. To b or not to b ?? A nonextensive view of b-value in the Gutenberg-Richter law.

    NASA Astrophysics Data System (ADS)

    Vallianatos, Filippos

    2014-05-01

    The Gutenberg-Richter (GR) (Gutenberg and Richter, 1944) law one of the cornerstones of modern seismology has been considered as a paradigm of manifestation of self-organized criticality since the dependence of the cumulative number of earthquakes with energy, i.e., the number of earthquakes with energy greater than E, behaves as a power law with the b value related to the critical exponent. A great number of seismic hazard studies have been originated as a result of this law. The Gutenberg-Richter (GR) law is an empirical relationship, which recent efforts relate it with general physical principles (Kagan and Knopoff, 1981; Wesnousky, 1999; Sarlis et al., 2010; Telesca, 2012; Vallianatos and Sammonds, 2013). Nonextensive statistical mechanics pioneered by Tsallis (Tsallis, 2009) provides a consistent theoretical framework for the studies of complex systems in their nonequilibrium stationary states, systems with multi fractal and self-similar structures, long-range interacting systems, etc. Earth is such system. In the present work we analyze the different pathways (originated in Sotolongo-Costa, A. Posadas , 2004; Silva et al., 2006) to extract the generalization of the G-R law as obtained in the frame of non extensive statistical physics. We estimate the b-value and we discuss its underline physics. This research has been funded by the European Union (European Social Fund) and Greek national resources under the framework of the "THALES Program: SEISMO FEAR HELLARC" project of the "Education & Lifelong Learning" Operational Programme. References Gutenberg, B. and C. F. Richter (1944). Bull. Seismol. Soc. Am. 34, 185-188. Kagan, Y. Y. and L. Knopoff (1981). J. Geophys. Res. 86, 2853-2862. Sarlis, N., E. Skordas and P. Varotsos (2010). Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 82 (2) , 021110. Silva, R., G. Franca, C. Vilar and J. Alcaniz (2006). Phys. Rev. E, 73, 026102 Sotolongo-Costa, O. and A. Posadas (2004). Phys. Rev. Lett., 92

  6. On the Bartnik mass of apparent horizons

    NASA Astrophysics Data System (ADS)

    Mantoulidis, Christos; Schoen, Richard

    2015-10-01

    In this paper we characterize the intrinsic geometry of apparent horizons (outermost marginally outer trapped surfaces) in asymptotically flat spacetimes; that is, the Riemannian metrics on the two sphere which can arise. Furthermore we determine the minimal ADM mass of a spacetime containing such an apparent horizon. The results are conveniently formulated in terms of the quasi-local mass introduced by Bartnik (1989 Phys. Rev. Lett. 62 2346-8). The Hawking mass provides a lower bound for Bartnik’s quasilocal mass on apparent horizons by way of Penrose’s conjecture on time symmetric slices, proven in 1997 by Huisken and Ilmanen (2001 J. Differ. Geom. 59 353-437) and in full generality in 1999 by Bray (2001 J. Differ. Geom. 59 177-267). We compute Bartnik’s mass for all non-degenerate apparent horizons and show that it coincides with the Hawking mass. As a corollary we disprove a conjecture due to Gibbons in the spirit of Thorne’s hoop conjecture (Gibbons 2009 arXiv:0903.1580), and construct a new large class of examples of apparent horizons with the integral of the negative part of the Gauss curvature arbitrarily large.

  7. The spatiotemporal analysis of the minimum magnitude of completeness Mc and the Gutenberg-Richter law b-value parameter using the earthquake catalog of Greece

    NASA Astrophysics Data System (ADS)

    Popandopoulos, G. A.; Baskoutas, I.; Chatziioannou, E.

    2016-03-01

    Spatiotemporal mapping the minimum magnitude of completeness Mc and b-value of the Gutenberg-Richter law is conducted for the earthquake catalog data of Greece. The data were recorded by the seismic network of the Institute of Geodynamics of the National Observatory of Athens (GINOA) in 1970-2010 and by the Hellenic Unified Seismic Network (HUSN) in 2011-2014. It is shown that with the beginning of the measurements at HUSN, the number of the recorded events more than quintupled. The magnitude of completeness Mc of the earthquake catalog for 1970-2010 varies within 2.7 to 3.5, whereas starting from April 2011 it decreases to 1.5-1.8 in the central part of the region and fluctuates around the average of 2.0 in the study region overall. The magnitude of completeness Mc and b-value for the catalogs of the earthquakes recorded by the old (GINOA) and new (HUSN) seismic networks are compared. It is hypothesized that the magnitude of completeness Mc may affect the b-value estimates. The spatial distribution of the b-value determined from the HUSN catalog data generally agrees with the main geotectonic features of the studied territory. It is shown that the b-value is below 1 in the zones of compression and is larger than or equal to 1 in the zones dominated by extension. The established depth dependence of the b-value is pretty much consistent with the hypothesis of a brittle-ductile transition zone existing in the Earth's crust. It is assumed that the source depth of a strong earthquake can probably be estimated from the depth distribution of the b-value, which can be used for seismic hazard assessment.

  8. High temperature strain gage apparent strain compensation

    NASA Technical Reports Server (NTRS)

    Holmes, Harlan K.; Moore, T. C., Sr.

    1992-01-01

    Once an installed strain gage is connected to a strain indicating device and the instrument is balanced, a subsequent change in temperature of the gage installation will generally produce a resistance change in the gage. This purely temperature-induced resistance will be registered by the indicating device as a strain and is referred to as 'apparent strain' to distinguish it from strain due to applied stress. One desirable technique for apparent strain compensation is to employ two identical gages with identical mounting procedures which are connected with a 'half bridge' configuration where gages see the same thermal environment but only one experiences a mechanical strain input. Their connection in adjacent arms of the bridge will then balance the thermally induced apparent strains and, in principle, only the mechanical strain remains. Two approaches that implement this technique are discussed.

  9. Apparent subdiffusion inherent to single particle tracking.

    PubMed Central

    Martin, Douglas S; Forstner, Martin B; Käs, Josef A

    2002-01-01

    Subdiffusion and its causes in both in vivo and in vitro lipid membranes have become the focus of recent research. We report apparent subdiffusion, observed via single particle tracking (SPT), in a homogeneous system that only allows normal diffusion (a DMPC monolayer in the fluid state). The apparent subdiffusion arises from slight errors in finding the actual particle position due to noise inherent in all experimental SPT systems. A model is presented that corrects this artifact, and predicts the time scales after which the effect becomes negligible. The techniques and results presented in this paper should be of use in all SPT experiments studying normal and anomalous diffusion. PMID:12324428

  10. Apparent subdiffusion inherent to single particle tracking.

    PubMed

    Martin, Douglas S; Forstner, Martin B; Käs, Josef A

    2002-10-01

    Subdiffusion and its causes in both in vivo and in vitro lipid membranes have become the focus of recent research. We report apparent subdiffusion, observed via single particle tracking (SPT), in a homogeneous system that only allows normal diffusion (a DMPC monolayer in the fluid state). The apparent subdiffusion arises from slight errors in finding the actual particle position due to noise inherent in all experimental SPT systems. A model is presented that corrects this artifact, and predicts the time scales after which the effect becomes negligible. The techniques and results presented in this paper should be of use in all SPT experiments studying normal and anomalous diffusion. PMID:12324428

  11. Additional Value of Diffusion-weighted MRI to Gd-EOB-DTPA-enhanced Hepatic MRI for the Detection of Liver Metastasis: the Difference Depending on the Experience of the Radiologists.

    PubMed

    Fukumoto, Wataru; Nakamura, Yuko; Higaki, Toru; Tatsugami, Fuminari; Iida, Makoto; Awai, Kazuo

    2015-06-01

    This retrospective study was to investigate whether adding diffusion-weighted imaging (DWI) to Gd-EOB-DTPA-enhanced MRI (EOB-MRI) improved the detection of liver metastasis in radiology resident and board-certified radiologist groups. It was approved by our institutional review board. We selected 18 patients with 35 liver metastases and 12 patients without liver tumors. Five board-certified radiologists and 5 radiology residents participated in the observer performance study. Each observer first interpreted T1- and T2-weighted-, plain-, arterial phase-, and hepatobiliary phase images and specified the location of the liver metastases. The software subsequently displayed the DWI images simultaneously and all participants repeated the reading. We used Jackknife alternative free-response receiver operating characteristic (JAFROC) analysis to compare the observer performance in detecting liver metastases. The mean values for the area under the curve (AUC) for EOB-MRI without and with DWI were 0.78 ± 0.13 [standard deviation: SD] and 0.87 ± 0.09, respectively, for the radiology residents, and the difference was statistically significant (p = 0.045). For the board- certified radiologists these values were 0.92 ± 0.02 and 0.96 ± 0.01, respectively, and the difference was not statistically significant (p = 0.092). EOB-MRI with DWI significantly improved the performance of radiology residents in the identification of liver metastases. PMID:26211220

  12. Central Nervous System Lymphoma in a 3-Year-Old Male Suffering from a Severe Juvenile Xanthogranuloma – the Usefulness of Perfusion Weighted Imaging and Diffusion Weighted Imaging in the Diagnostics of Pediatric Brain Tumors

    PubMed Central

    Neska-Matuszewska, Małgorzata; Zimny, Anna; Kałwak, Krzysztof; Sąsiadek, Marek J.

    2015-01-01

    Summary Background Primary Central Nervous System Lymphomas (PCNSLs) are rare, malignant brain tumors derived from lymphocytes B. Juvenile xanthogranuloma (JXG) is a non-Langerhans histiocytic cell disorder in children which mostly affects the skin. Rare fatalities have been reported in extracutaneous manifestation. Brain magnetic resonance imaging (MRI) is a method of choice in the diagnostics of all neoplastic CNS lesions. Perfusion weighted imaging (PWI) and diffusion weighted imaging (DWI) allow for more detailed analysis of brain tumors including the rate of neoangiogenesis and cellularity. We presented a pediatric patient suffering from JXG with CNS involvement and the role of brain MRI including DWI and PWI in the evaluation of brain focal lesions. Case Report A 3-year-old male with severe JXG underwent two stem cell transplantations with a development of neurological complications. The patient underwent emergency CT and MRI which revealed a non-specific enhancing focal brain lesion. In DWI it showed restricted diffusion while PWI revealed low values of rCBV and the signal intensity curve returning above the baseline level. Advanced MRI techniques such as DWI and PWI suggested PCNSL. Stereotactic biopsy confirmed PCNSL due to Ebstein-Barr virus reactivation. Conclusions The use of advanced MRI sequences is important to differentiate brain lesions in pediatric patients. The use of PWI and DWI facilitated the diagnosis of PCNSL. It is important to remember that PCNSLs show a very typical pattern of changes visualized with MRI such as: usually strong homogenous enhancement, restricted diffusion and low perfusion. PMID:25624957

  13. Modeling the interrelation between asperity distributions and b-values by means of a modified Olami-Feder-Christensen model

    NASA Astrophysics Data System (ADS)

    Avlonitis, Markos; Papadopoulos, Gerassimos

    2013-04-01

    the fault, is estimated through simulation experiments. It is shown that for a wide range of model parameters there is a clear monotonic relationship between the real contact area of asperities and the corresponding power-law exponent b. As a result, based to the proposed model, the different macroscopic b-values can be mapped by different asperity distributions within the fault.

  14. Apparent extended body motions in depth

    NASA Technical Reports Server (NTRS)

    Hecht, Heiko; Proffitt, Dennis R.

    1991-01-01

    Five experiments were designed to investigate the influence of three-dimensional (3-D) orientation change on apparent motion. Projections of an orientation-specific 3-D object were sequentially flashed in different locations and at different orientations. Such an occurrence could be resolved by perceiving a rotational motion in depth around an axis external to the object. Consistent with this proposal, it was found that observers perceived curved paths in depth. Although the magnitude of perceived trajectory curvature often fell short of that required for rotational motions in depth (3-D circularity), judgments of the slant of the virtual plane on which apparent motions occurred were quite close to the predictions of a model that proposes circular paths in depth.

  15. Anomalously high b-values in the South Flank of Kilauea volcano, Hawaii: Evidence for the distribution of magma below Kilauea's East rift zone

    USGS Publications Warehouse

    Wyss, M.; Klein, F.; Nagamine, K.; Wiemer, S.

    2001-01-01

    The pattern of b-value of the frequency-magnitude relation, or mean magnitude, varies little in the Kaoiki-Hilea area of Hawaii, and the b-values are normal, with b = 0.8 in the top 10 km and somewhat lower values below that depth. We interpret the Kaoiki-Hilea area as relatively stable, normal Hawaiian crust. In contrast, the b-values beneath Kilauea's South Flank are anomalously high (b = 1.3-1.7) at depths between 4 and 8 km, with the highest values near the East Rift zone, but extending 5-8 km away from the rift. Also, the anomalously high b-values vary along strike, parallel to the rift zone. The highest b-values are observed near Hiiaka and Pauahi craters at the bend in the rift, the next highest are near Makaopuhi and also near Puu Kaliu. The mildest anomalies occur adjacent to the central section of the rift. The locations of the three major and two minor b-value anomalies correspond to places where shallow magma reservoirs have been proposed based on analyses of seismicity, geodetic data and differentiated lava chemistry. The existence of the magma reservoirs is also supported by magnetic anomalies, which may be areas of dike concentration, and self-potential anomalies, which are areas of thermal upwelling above a hot source. The simplest explanation of these anomalously high b-values is that they are due to the presence of active magma bodies beneath the East Rift zone at depths down to 8 km. In other volcanoes, anomalously high b-values correlate with volumes adjacent to active magma chambers. This supports a model of a magma body beneath the East Rift zone, which may widen and thin along strike, and which may reach 8 km depth and extend from Kilauea's summit to a distance of at least 40 km down rift. The anomalously high b-values at the center of the South Flank, several kilometers away from the rift, may be explained by unusually high pore pressure throughout the South Flank, or by anomalously strong heterogeneity due to extensive cracking, or by both

  16. Comment: An Apparent Controversy in Auroral Physics

    NASA Astrophysics Data System (ADS)

    Haerendel, Gerhard

    2007-03-01

    In his article ``A turning point in auroral physics,'' Bryant argued against what he called the `standard' theory of auroral acceleration, according to which the electrons ``gain their energy from static electric fields,'' and offered wave acceleration as an alternative. Because of the importance of the process, not only for the aurora borealis but also for other cosmic plasmas, a clarification of this apparent controversy seems to be in place.

  17. The Apparent Thermal Conductivity of Pozzolana Concrete

    NASA Astrophysics Data System (ADS)

    Bessenouci, M. Z.; Triki, N. E. Bibi; Khelladi, S.; Draoui, B.; Abene, A.

    The recent development of some lightweight construction materials, such as light concrete, can play an important role as an insulator, while maintaining sufficient levels of mechanical performance. The quality of insulation to provide depends on the climate, the exposure of the walls and also the materials used in the construction. The choice of a material to be used as an insulator, obviously, depends on its availability and its cost. This is a study of natural pozzolanas as basic components in building materials. It is intended to highlight their thermal advantage. It is economically advantageous to use pozzolana in substitution for a portion of the clinker as hydraulically active additions, as well as in compositions of lightweight concretes in the form of pozzolanic aggregate mixtures, which provide mechanical strengths that comply with current standards. A theoretical study is conducted on the apparent thermal conductivity of building materials, namely concrete containing pozzolana. Thermal modeling, apparent to that commonly used for porous materials, has been applied to pozzolana concrete. Experimental results on measurements of the apparent thermal conductivity of pozzolana concrete are reported in this study, using an approach that considers that concrete is composed of two solid ingredients, a binding matrix (hydrated cement paste) and all aggregates. A second comparative theoretical approach is used for the case where concrete consists of a solid phase and a fluid phase (air).

  18. Apparent Solar Tornado-Like Prominences

    NASA Astrophysics Data System (ADS)

    Panasenco, Olga; Martin, Sara F.; Velli, Marco

    2014-02-01

    Recent high-resolution observations from the Solar Dynamics Observatory (SDO) have reawakened interest in the old and fascinating phenomenon of solar tornado-like prominences. This class of prominences was first introduced by Pettit ( Astrophys. J. 76, 9, 1932), who studied them over many years. Observations of tornado prominences similar to the ones seen by SDO had already been documented by Secchi ( Le Soleil, 1877). High-resolution and high-cadence multiwavelength data obtained by SDO reveal that the tornado-like appearance of these prominences is mainly an illusion due to projection effects. We discuss two different cases where prominences on the limb might appear to have a tornado-like behavior. One case of apparent vortical motions in prominence spines and barbs arises from the (mostly) 2D counterstreaming plasma motion along the prominence spine and barbs together with oscillations along individual threads. The other case of apparent rotational motion is observed in a prominence cavity and results from the 3D plasma motion along the writhed magnetic fields inside and along the prominence cavity as seen projected on the limb. Thus, the "tornado" impression results either from counterstreaming and oscillations or from the projection on the plane of the sky of plasma motion along magnetic-field lines, rather than from a true vortical motion around an (apparent) vertical or horizontal axis. We discuss the link between tornado-like prominences, filament barbs, and photospheric vortices at their base.

  19. SU-E-P-33: Critical Role of T2-Weighted Imaging Combined with Diffusion-Weighted Imaging of MRI in Diagnosis of Loco-Regional Recurrent Esophageal Cancer After Radical Surgery

    SciTech Connect

    Deng, G; Qiao, L; Liang, N; Xie, J; Zhang, J; Luo, H; Zhang, J

    2015-06-15

    Purpose: We perform this study to investigate the diagnostic efficacy of T2-weighted MRI (T2WI) and diffusion-weighted MRI (DWI) in confirming local relapses of esophageal cancer in patients highly suspected of recurrence after eradicating surgery. Methods: Forty-two postoperative esophageal cancer patients with clinical suspicions of cancer recurrence underwent 3.0T MRI applying axial, coronal, sagittal T2WI and axial DWI sequences. Two experienced radiologists (R1 and R2) both used two methods (T2WI, T2WI+DWI) to observe the images, and graded the patients ranging from 1 to 5 to represent severity of the disease based on visual signal intensity (patients equal to or more than grade 3 was confirmed as recurrent disease) Results: 27/42patients were verified of recurrent disease by pathologic findings and/or imaging findings during follow-up. The sensitivity, specificity and accuracy of R1 applying T2WI+DWI are 96%, 87% and 93% versus 81%, 80% and 77% on T2WI, these figures by R2 were 96%, 93% and 95% versus 89%, 93% and 90%. The receiver operating curve (ROC) analyses suggest that both of the two readers can obtain better accuracy when adding DWI to T2WI compared with T2WI alone. Kappa test between R1 and R2 indicates excellent inter-observer agreement on T2WI+DWI. Conclusion: Standard T2WI in combination DWI can achieve better accuracy than T2WI alone in diagnosing local recurrence of esophageal cancer, and improve consistency between different readers.

  20. Validity of Acute Stroke Lesion Volume Estimation by Diffusion-Weighted Imaging–Alberta Stroke Program Early Computed Tomographic Score Depends on Lesion Location in 496 Patients With Middle Cerebral Artery Stroke

    PubMed Central

    Schröder, Julian; Cheng, Bastian; Ebinger, Martin; Köhrmann, Martin; Wu, Ona; Kang, Dong-Wha; Liebeskind, David S.; Tourdias, Thomas; Singer, Oliver C.; Christensen, Soren; Campbell, Bruce; Luby, Marie; Warach, Steven; Fiehler, Jens; Fiebach, Jochen B.; Gerloff, Christian; Thomalla, Götz

    2016-01-01

    Background and Purpose Alberta Stroke Program Early Computed Tomographic Score (ASPECTS) has been used to estimate diffusion-weighted imaging (DWI) lesion volume in acute stroke. We aimed to assess correlations of DWI-ASPECTS with lesion volume in different middle cerebral artery (MCA) subregions and reproduce existing ASPECTS thresholds of a malignant profile defined by lesion volume ≥100 mL. Methods We analyzed data of patients with MCA stroke from a prospective observational study of DWI and fluid-attenuated inversion recovery in acute stroke. DWI-ASPECTS and lesion volume were calculated. The population was divided into subgroups based on lesion localization (superficial MCA territory, deep MCA territory, or both). Correlation of ASPECTS and infarct volume was calculated, and receiver-operating characteristics curve analysis was performed to identify the optimal ASPECTS threshold for ≥100-mL lesion volume. Results A total of 496 patients were included. There was a significant negative correlation between ASPECTS and DWI lesion volume (r=−0.78; P<0.0001). With regards to lesion localization, correlation was weaker in deep MCA region (r=−0.19; P=0.038) when compared with superficial (r=−0.72; P<0.001) or combined superficial and deep MCA lesions (r=−0.72; P<0.001). Receiver-operating characteristics analysis revealed ASPECTS≤6 as best cutoff to identify ≥100-mL DWI lesion volume; however, positive predictive value was low (0.35). Conclusions ASPECTS has limitations when lesion location is not considered. Identification of patients with malignant profile by DWI-ASPECTS may be unreliable. ASPECTS may be a useful tool for the evaluation of noncontrast computed tomography. However, if MRI is used, ASPECTS seems dispensable because lesion volume can easily be quantified on DWI maps. PMID:25316278

  1. Diagnosis of lateral pelvic lymph node metastasis of T1 lower rectal cancer using diffusion-weighted magnetic resonance imaging: A case report with lateral pelvic lymph node dissection of lower rectal cancer

    PubMed Central

    OGAWA, SHIMPEI; ITABASHI, MICHIO; HIROSAWA, TOMOICHIRO; HASHIMOTO, TAKUZO; BAMBA, YOSHIKO; OKAMOTO, TAKAHIRO

    2016-01-01

    The present study presented a 35-year-old female patient in whom fecal occult blood was detected in a medical check-up. Colonoscopy revealed a superficial elevated-type tumor with central depression in the lower rectum. The tumor was diagnosed as T1 deep invasive cancer. No swollen lymph nodes or distant metastasis were found on computed tomography or [18F]-fluorodeoxyglucose-positron emission tomography with computed tomography. However, a swollen right lateral pelvic lymph node (LPLN; short axis 4 mm) was revealed on magnetic resonance imaging (MRI). This lymph node exhibited high intensity on diffusion-weighted imaging (DWI), suggesting metastasis. Low anterior resection, regional lymph node dissection and right LPLN dissection (LPLD) were performed. Histological analysis revealed metastasis in the right LPLN, as suggested by the high DWI intensity. The indication for LPLD in the current Japanese guidelines is based on the tumor location and depth of invasion (≥T3), however, not on the status of LPLN metastasis in pre-operative evaluation. The present case was cT1, which is not included in this indication. DWI is sensitive for the diagnosis of lymph node metastasis of colorectal cancer, although inflammation-induced swelling of lymph nodes in advanced rectal cancer may cause a false-positive result, which is uncommon in T1 cases. Therefore, an LPLN with a high intensity DWI signal in T1 cases is likely to be metastasis-positive. Pre-operative DWI-MRI may be useful for identifying LPLN metastasis when planning the treatment strategy in these cases. The present study suggested reinvestigation of the indication for LPLD with inclusion of LPLN status on pre-operative imaging. PMID:27123286

  2. Apparent horizons in binary black hole spacetimes

    NASA Astrophysics Data System (ADS)

    Shoemaker, Deirdre Marie

    Over the last decade, advances in computing technology and numerical techniques have lead to the possible theoretical prediction of astrophysically relevant waveforms in numerical simulations. With the building of gravitational wave detectors such as the Laser Interferometric Gravitational-Wave Observatory, we stand at the epoch that will usher in the first experimental study of strong field general relativity. One candidate source for ground based detection of gravitational waveforms, the orbit and merger of two black holes, is of great interest to the relativity community. The binary black hole problem is the two-body problem in general relativity. It is a stringent dynamical test of the theory. The problem involves the evolution of the Einstein equation, a complex system of non-linear, dynamic, elliptic-hyperbolic equations intractable in closed form. Numerical relativists are now developing the technology to evolve the Einstein equation using numerical simulations. The generation of these numerical I codes is a ``theoretical laboratory'' designed to study strong field phenomena in general relativity. This dissertation reports the successful development and application of the first multiple apparent horizon tracker applied to the generic binary black hole problem. I have developed a method that combines a level set of surfaces with a curvature flow method. This method, which I call the level flow method, locates the surfaces of any apparent horizons in the spacetime. The surface location then is used to remove the singularities from the computational domain in the evolution code. I establish the following set of criteria desired in an apparent horizon tracker: (1)The robustness of the tracker due to its lack of dependence on small changes to the initial guess; (2)The generality of the tracker in its applicability to generic spacetimes including multiple back hole spacetimes; and (3)The efficiency of the tracker algorithm in CPU time. I demonstrate the apparent

  3. The use of MRI apparent diffusion coefficient (ADC) in monitoring the development of brain infarction

    PubMed Central

    2011-01-01

    Background To study the rules that apparent diffusion coefficient (ADC) changes with time and space in cerebral infarction, and to provide the evidence in defining the infarction stages. Methods 117 work-ups in 98 patients with cerebral infarction (12 hyperacute, 43 acute, 29 subacute, 10 steady, and 23 chronic infarctions) were imaged with both conventional MRI and diffusion weighted imaging. The average ADC values, the relative ADC (rADC) values, and the ADC values or rADC values from the center to the periphery of the lesion were calculated. Results The average ADC values and the rADC values of hyperacute and acute infarction lesion depressed obviously. rADC values in hyperacute and acute stage was minimized, and increased progressively as time passed and appeared as "pseudonormal" values in approximately 8 to 14 days. Thereafter, rADC values became greater than normal in chronic stage. There was positive correlation between rADC values and time (P < 0.01). The ADC values and the rADC values in hyperacute and acute lesions had gradient signs that these lesions increased from the center to the periphery. The ADC values and the rADC values in subacute lesions had adverse gradient signs that these lesions decreased from the center to the periphery. Conclusion The ADC values of infarction lesions have evolution rules with time and space. The evolution rules with time and those in space can be helpful to decide the clinical stage, and to provide the evidence in guiding the treatment or judging the prognosis in infarction. PMID:21211049

  4. Value of Apparent Diffusion Coefficient Values in Differentiating Malignant and Benign Breast Lesions

    PubMed Central

    Bozkurt Bostan, Tuğba; Koç, Gonca; Sezgin, Gülten; Altay, Canan; Fazıl Gelal, M.; Oyar, Orhan

    2016-01-01

    Background: Magnetic resonance imaging (MRI) has become a diagnostic and problem solving method for the breast examinations in addition to conventional breast examination methods. Diffusion-weighted imaging (DWI) adds valuable information to conventional MRI. Aims: Our aim was to show the impact of apparent diffusion coefficient (ADC) values acquired with DWI to differentiate benign and malignant breast lesions. Study Design: Diagnostic accuracy study. Methods: Forty-six women with 58 breast masses (35 malignant, 23 benign) were examined on a 1.5 T clinical MRI scanner. The morphologic characteristics of the lesions on conventional MRI sequences and contrast uptake pattern were assessed. ADC values of both lesions and normal breast parenchyma were measured. The ADC values obtained were statistically compared with the histopathologic results using Paired Samples t-Test. Results: Multiple lesions were detected in 12 (26%) of the patients, while only one lesion was detected in 34 (74%). Overall, 35 lesions out of 58 were histopathologically proven to be malignant. In the dynamic contrast-enhanced series, 5 of the malignant lesions were type 1, while 8 benign lesions revealed either type 2 or 3 time signal intensity curves (85% sensitivity, 56% spesifity). Mean ADC values were significantly different in malignant vs. benign lesions. (1.04±0.29×10−3 cm2/sec vs. 1.61±0.50×10−3 cm2/sec for the malignant and benign lesions, respectively, p=0.03). A cut-off value of 1.30×10−3 mm2/sec for ADC detected with receiver operating characteristic analysis yielded 89.1% sensitivity and 100% specificity for the differentiation between benign and malignant lesions. Conclusion: ADC values improve the diagnostic accuracy of solid breast lesions when evaluated with the conventional MRI sequences. Therefore, DWI should be incorporated to routine breast MRI protocol. PMID:27308073

  5. Apparent Diffusion Coefficient analysis of encephalitis: A comparative study with topographic evaluation and conventional MRI findings

    PubMed Central

    Katirag, Ahmet; Beker-Acay, Mehtap; Unlu, Ebru; Demirbas, Hayri; Demirturk, Nese

    2016-01-01

    Objective: Our purpose was to reveal the efficiency of diffusion weighted imaging (DWI) in the diagnosis of encephalitis, and to determine the relation between the apparent diffusion coefficient (ADC) values, the onset of the clinical symptoms, and the lesion extent. Methods: Conventional magnetic resonance imaging (MRI) was performed in 17 patients with encephalitis diagnosed on the basis of laboratory, clinical and radiologic findings during 2009 and 2015. Based on the duration between the onset of the symptoms and the brain MRI findings, the patients were divided into three groups. ADC values of the encephalitis lesion, the lesions’ topographic analysis score, deep gray matter involvement, patients’ clinical situation and the duration of the arrival to the clinic was examined. Results: Mean ADC values were 0,988±0,335 x10-3 mm2/s in group I (0-2 days), 1,045±0,347 x10-3 mm2/s in Group-II (3-7 days), 1,451±0,225 x10-3 mm2/s in Group-III (8 days and over). The relation between the ADC values and the duration of the arrival, topographic analysis score, the relation between the patients’ clinical situation and the deep gray matter involvement were found to be statistically significant. The deep gray matter involvement was demonstrated more clearly by FLAIR images when compared with DWI. Conclusion: Conventional MRI sequences may be insufficient in showing the encephalitis lesion. DWI must be added to the imaging modalities immediately in the cases suspected of having encephalitis. PMID:27375722

  6. Apparent magnitude of earthshine: a simple calculation

    NASA Astrophysics Data System (ADS)

    Agrawal, Dulli Chandra

    2016-05-01

    The Sun illuminates both the Moon and the Earth with practically the same luminous fluxes which are in turn reflected by them. The Moon provides a dim light to the Earth whereas the Earth illuminates the Moon with somewhat brighter light which can be seen from the Earth and is called earthshine. As the amount of light reflected from the Earth depends on part of the Earth and the cloud cover, the strength of earthshine varies throughout the year. The measure of the earthshine light is luminance, which is defined in photometry as the total luminous flux of light hitting or passing through a surface. The expression for the earthshine light in terms of the apparent magnitude has been derived for the first time and evaluated for two extreme cases; firstly, when the Sun’s rays are reflected by the water of the oceans and secondly when the reflector is either thick clouds or snow. The corresponding values are -1.30 and -3.69, respectively. The earthshine value -3.22 reported by Jackson lies within these apparent magnitudes. This paper will motivate the students and teachers of physics to look for the illuminated Moon by earthlight during the waning or waxing crescent phase of the Moon and to reproduce the expressions derived here by making use of the inverse-square law of radiation, Planck’s expression for the power in electromagnetic radiation, photopic spectral luminous efficiency function and expression for the apparent magnitude of a body in terms of luminous fluxes.

  7. Premature Ventricular Complexes in Apparently Normal Hearts.

    PubMed

    Luebbert, Jeffrey; Auberson, Denise; Marchlinski, Francis

    2016-09-01

    Premature ventricular complexes (PVCs) are consistently associated with worse prognosis and higher morbidity and mortality. This article reviews PVCs and their presentation in patients with an apparently normal heart. Patients with PVCs may be completely asymptomatic, whereas others may note severely disabling symptoms. Cardiomyopathy may occur with frequent PVCs. Diagnostic work-up is directed at obtaining 12-lead ECG to characterize QRS morphology, Holter monitor to assess frequency, and echo and advanced imaging to assess for early cardiomyopathy and exclude structural heart disease. Options for management include watchful waiting, medical therapy, or catheter ablation. Malignant variants of PVCs may induce ventricular fibrillation even in a normal heart. PMID:27521085

  8. Osteosarcoma With Apparent Ewing Sarcoma Gene Rearrangement.

    PubMed

    Mathias, Melissa D; Chou, Alexander J; Meyers, Paul; Shukla, Neerav; Hameed, Meera; Agaram, Narasimhan; Wang, Lu; Berger, Michael F; Walsh, Michael; Kentsis, Alex

    2016-07-01

    Poorly differentiated round cell sarcomas present diagnostic challenges because of their variable morphology and lack of specific immunophenotypic markers. We present a case of a 15-year-old female with a tibial tumor that exhibited features of Ewing-like sarcoma, including apparent rearrangement of the EWSR1 gene. Hybridization capture-based next-generation DNA sequencing showed evidence of complex genomic rearrangements, absence of known pathogenic Ewing-like chromosome translocations, and deletions RB1, PTCH1, and ATRX, supporting the diagnosis of osteosarcoma. This illustrates the potential of clinical genomic profiling to improve diagnosis and enable specifically targeted therapies for cancers with complex pathologies. PMID:27352193

  9. Apparent contact angle of an evaporating drop

    NASA Astrophysics Data System (ADS)

    Morris, S. J. S.

    2012-11-01

    In experiments by Poulard et al. (2005), a sessile drop of perfectly wetting liquid evaporates from a non-heated substrate into an under-saturated mixture of vapour with an inert gas; evaporation is limited by vapour diffusion. The system exhibits an apparent contact angle θ that is a flow property. Under certain conditions, the apparent contact line was stationary relative to the substrate; we predict θ for this case. Observed values of θ are small, allowing lubrication analysis of the liquid film. The liquid and vapour flows are coupled through conditions holding at the phase interface; in particular, vapour partial pressure there is related to the local value of liquid pressure through the Kelvin condition. Because the droplet is shallow, the interfacial conditions can be transferred to the solid-liquid interface at y = 0 . We show that the dimensionless partial pressure p (x , y) and the film thickness h (x) are determined by solving ∇2 p = 0 for y > 0 subject to a matching condition at infinity, and the conditions - p = L hxx +h-3 and (h3px) x + 3py = 0 at y = 0 . The parameter L controls the ratio of Laplace to disjoining pressure. We analyse this b.v.p. for the experimentally-relevant case L --> 0 .

  10. Fiber estimation and tractography in diffusion MRI: development of simulated brain images and comparison of multi-fiber analysis methods at clinical b-values.

    PubMed

    Wilkins, Bryce; Lee, Namgyun; Gajawelli, Niharika; Law, Meng; Leporé, Natasha

    2015-04-01

    Advances in diffusion-weighted magnetic resonance imaging (DW-MRI) have led to many alternative diffusion sampling strategies and analysis methodologies. A common objective among methods is estimation of white matter fiber orientations within each voxel, as doing so permits in-vivo fiber-tracking and the ability to study brain connectivity and networks. Knowledge of how DW-MRI sampling schemes affect fiber estimation accuracy, tractography and the ability to recover complex white-matter pathways, differences between results due to choice of analysis method, and which method(s) perform optimally for specific data sets, all remain important problems, especially as tractography-based studies become common. In this work, we begin to address these concerns by developing sets of simulated diffusion-weighted brain images which we then use to quantitatively evaluate the performance of six DW-MRI analysis methods in terms of estimated fiber orientation accuracy, false-positive (spurious) and false-negative (missing) fiber rates, and fiber-tracking. The analysis methods studied are: 1) a two-compartment "ball and stick" model (BSM) (Behrens et al., 2003); 2) a non-negativity constrained spherical deconvolution (CSD) approach (Tournier et al., 2007); 3) analytical q-ball imaging (QBI) (Descoteaux et al., 2007); 4) q-ball imaging with Funk-Radon and Cosine Transform (FRACT) (Haldar and Leahy, 2013); 5) q-ball imaging within constant solid angle (CSA) (Aganj et al., 2010); and 6) a generalized Fourier transform approach known as generalized q-sampling imaging (GQI) (Yeh et al., 2010). We investigate these methods using 20, 30, 40, 60, 90 and 120 evenly distributed q-space samples of a single shell, and focus on a signal-to-noise ratio (SNR = 18) and diffusion-weighting (b = 1000 s/mm(2)) common to clinical studies. We found that the BSM and CSD methods consistently yielded the least fiber orientation error and simultaneously greatest detection rate of fibers. Fiber detection

  11. Fiber estimation and tractography in diffusion MRI: Development of simulated brain images and comparison of multi-fiber analysis methods at clinical b-values

    PubMed Central

    Wilkins, Bryce; Lee, Namgyun; Gajawelli, Niharika; Law, Meng; Leporé, Natasha

    2015-01-01

    Advances in diffusion-weighted magnetic resonance imaging (DW-MRI) have led to many alternative diffusion sampling strategies and analysis methodologies. A common objective among methods is estimation of white matter fiber orientations within each voxel, as doing so permits in-vivo fiber-tracking and the ability to study brain connectivity and networks. Knowledge of how DW-MRI sampling schemes affect fiber estimation accuracy, and consequently tractography and the ability to recover complex white-matter pathways, as well as differences between results due to choice of analysis method and which method(s) perform optimally for specific data sets, all remain important problems, especially as tractography-based studies become common. In this work we begin to address these concerns by developing sets of simulated diffusion-weighted brain images which we then use to quantitatively evaluate the performance of six DW-MRI analysis methods in terms of estimated fiber orientation accuracy, false-positive (spurious) and false-negative (missing) fiber rates, and fiber-tracking. The analysis methods studied are: 1) a two-compartment “ball and stick” model (BSM) (Behrens et al., 2003); 2) a non-negativity constrained spherical deconvolution (CSD) approach (Tournier et al., 2007); 3) analytical q-ball imaging (QBI) (Descoteaux et al., 2007); 4) q-ball imaging with Funk-Radon and Cosine Transform (FRACT) (Haldar and Leahy, 2013); 5) q-ball imaging within constant solid angle (CSA) (Aganj et al., 2010); and 6) a generalized Fourier transform approach known as generalized q-sampling imaging (GQI) (Yeh et al., 2010). We investigate these methods using 20, 30, 40, 60, 90 and 120 evenly distributed q-space samples of a single shell, and focus on a signal-to-noise ratio (SNR = 18) and diffusion-weighting (b = 1000 s/mm2) common to clinical studies. We found the BSM and CSD methods consistently yielded the least fiber orientation error and simultaneously greatest detection rate of

  12. Spatial Distribution of b-value of the Copahue volcano during 2012-2014 eruptive period: Relationship between magmatic and hydrothermal system

    NASA Astrophysics Data System (ADS)

    Lazo, Jonathan; Basualto, Daniel; Bengoa, Cintia; Cardona, Carlos; Franco, Luis; Gil-Cruz, Fernando; Hernández, Erasmo; Lara, Luis; Lundgren, Paul; Medina, Roxana; Morales, Sergio; Peña, Paola; Quijada, Jonathan; Samsonov, Sergey; San Martin, Juan; Valderrama, Oscar

    2015-04-01

    Temporal and spatial variations of b-value have been interpreted as regional stress changes on active tectonic zones or magma ascent and/or hydrothermal fluids mobilization that could affect to active volcanic arc. Increasing of fluids pressure, medium heterogeneities or temperature changes would be the cause of these variations. The Copahue volcano is a shield strato-volcano that has been edified on the western margin of the Caviahue Caldera, located in the international border between Chile and Argentina, which contain an important geothermic field and is located at a horse-tail structure of the Liquiñe-Ofqui Fault Zone. The pre-fracture nature of its basement, as well as an extensive geothermic field, would be producing very complex conditions to fluids movement that could be exploring to use the 'b' value of the recorded seismicity between 2012 and 2014. Based in the database of VT seismic events, we used 2.073 events to calculate the b-value to obtain the 2D and 3D distribution maps. Results showed two anomalous zones: the first one located 9 Km to NE of the active crater, 3-6 Km depth, with high b-values (>1.2) that is associated with a very high production rate of small earthquakes that could suggest a brittle zone, located in the active geothermal field. The second zone, showed a low b-values (~ 0.7), located to east of the volcano edifice at <3 Km depth, associated to a zone where were generated larger magnitude events, suggesting a zone with more stress accumulation that well correlated with the deformation center detected by InSAR measurements. This zone could be interpreted as the magmatic source that interacts with the shallow hydrothermal system. Thus, in a very complex setting as a volcano sitting on top of a geothermal system, the b-value offers a tool to understand the distribution of the seismic sources and hence a physical constrain for the coupled magmatic/hydrothermal system.

  13. Apparent diffusion coefficient and fractional anisotropy of newly diagnosed grade II gliomas†

    PubMed Central

    Khayal, Inas S.; McKnight, Tracy R.; McGue, Colleen; Vandenberg, Scott; Lamborn, Kathleen R.; Chang, Susan M.; Cha, Soonmee; Nelson, Sarah J.

    2013-01-01

    Distinguishing between low-grade oligodendrogliomas (ODs) and astrocytomas (AC) is of interest for defining prognosis and stratifying patients to specific treatment regimens. The purpose of this study was to determine if the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) from diffusion imaging can help to differentiate between newly diagnosed grade II OD and AC subtypes and to evaluate the ADC and FA values for the mixed population of oligoastrocytomas (OA). Fifty-three patients with newly diagnosed grade II gliomas were studied using a 1.5T whole body scanner (23 ODs, 16 ACs, and 14 OAs). The imaging protocol included post-gadolinium T1-weighted images, T2-weighted images, and either three and/or six directional diffusion imaging sequence with b = 1000 s/mm2. Diffusion-weighted images were analyzed using in-house software to calculate maps of ADC and for six directional acquisitions, FA. The intensity values were normalized by values from normal appearing white matter (NAWM) to generate maps of normalized apparent diffusion coefficient (nADC) and normalized fractional anisotropy (nFA). The hyperintense region in the T2 weighted image was defined as the T2All region. A Mann–Whitney rank-sum test was performed on the 25th, median, and 75th nADC and nFA among the three subtypes. Logistic regression was performed to determine how well the nADC and nFA predict subtype. Lesions diagnosed as being OD had significantly lower nADC and significantly higher nFA, compared to AC. The nADC and nFA values individually classified the data with an accuracy of 87%. Combining the two did not enhance the classification. The patients with OA had nADC and nFA values between those of OD and AC. This suggests that ADC and FA may be helpful in directing tissue sampling to the most appropriate regions for taking biopsies in order to make a definitive diagnosis. PMID:19125391

  14. Apparent diffusion coefficient and fractional anisotropy of newly diagnosed grade II gliomas.

    PubMed

    Khayal, Inas S; McKnight, Tracy R; McGue, Colleen; Vandenberg, Scott; Lamborn, Kathleen R; Chang, Susan M; Cha, Soonmee; Nelson, Sarah J

    2009-05-01

    Distinguishing between low-grade oligodendrogliomas (ODs) and astrocytomas (AC) is of interest for defining prognosis and stratifying patients to specific treatment regimens. The purpose of this study was to determine if the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) from diffusion imaging can help to differentiate between newly diagnosed grade II OD and AC subtypes and to evaluate the ADC and FA values for the mixed population of oligoastrocytomas (OA). Fifty-three patients with newly diagnosed grade II gliomas were studied using a 1.5T whole body scanner (23 ODs, 16 ACs, and 14 OAs). The imaging protocol included post-gadolinium T1-weighted images, T2-weighted images, and either three and/or six directional diffusion imaging sequence with b = 1000 s/mm(2). Diffusion-weighted images were analyzed using in-house software to calculate maps of ADC and for six directional acquisitions, FA. The intensity values were normalized by values from normal appearing white matter (NAWM) to generate maps of normalized apparent diffusion coefficient (nADC) and normalized fractional anisotropy (nFA). The hyperintense region in the T2 weighted image was defined as the T2All region. A Mann-Whitney rank-sum test was performed on the 25th, median, and 75th nADC and nFA among the three subtypes. Logistic regression was performed to determine how well the nADC and nFA predict subtype. Lesions diagnosed as being OD had significantly lower nADC and significantly higher nFA, compared to AC. The nADC and nFA values individually classified the data with an accuracy of 87%. Combining the two did not enhance the classification. The patients with OA had nADC and nFA values between those of OD and AC. This suggests that ADC and FA may be helpful in directing tissue sampling to the most appropriate regions for taking biopsies in order to make a definitive diagnosis. PMID:19125391

  15. Computing the apparent centroid of radar targets

    SciTech Connect

    Lee, C.E.

    1996-12-31

    A high-frequency multibounce radar scattering code was used as a simulation platform for demonstrating an algorithm to compute the ARC of specific radar targets. To illustrate this simulation process, several targets models were used. Simulation results for a sphere model were used to determine the errors of approximation associated with the simulation; verifying the process. The severity of glint induced tracking errors was also illustrated using a model of an F-15 aircraft. It was shown, in a deterministic manner, that the ARC of a target can fall well outside its physical extent. Finally, the apparent radar centroid simulation based on a ray casting procedure is well suited for use on most massively parallel computing platforms and could lead to the development of a near real-time radar tracking simulation for applications such as endgame fuzing, survivability, and vulnerability analyses using specific radar targets and fuze algorithms.

  16. Ambiguity in Tactile Apparent Motion Perception

    PubMed Central

    Liaci, Emanuela; Bach, Michael; Tebartz van Elst, Ludger; Heinrich, Sven P.; Kornmeier, Jürgen

    2016-01-01

    Background In von Schiller’s Stroboscopic Alternative Motion (SAM) stimulus two visually presented diagonal dot pairs, located on the corners of an imaginary rectangle, alternate with each other and induce either horizontal, vertical or, rarely, rotational motion percepts. SAM motion perception can be described by a psychometric function of the dot aspect ratio (“AR”, i.e. the relation between vertical and horizontal dot distances). Further, with equal horizontal and vertical dot distances (AR = 1) perception is biased towards vertical motion. In a series of five experiments, we presented tactile SAM versions and studied the role of AR and of different reference frames for the perception of tactile apparent motion. Methods We presented tactile SAM stimuli and varied the ARs, while participants reported the perceived motion directions. Pairs of vibration stimulators were attached to the participants’ forearms and stimulator distances were varied within and between forearms. We compared straight and rotated forearm conditions with each other in order to disentangle the roles of exogenous and endogenous reference frames. Results Increasing the tactile SAM’s AR biased perception towards vertical motion, but the effect was weak compared to the visual modality. We found no horizontal disambiguation, even for very small tactile ARs. A forearm rotation by 90° kept the vertical bias, even though it was now coupled with small ARs. A 45° rotation condition with crossed forearms, however, evoked a strong horizontal motion bias. Discussion Existing approaches to explain the visual SAM bias fail to explain the current tactile results. Particularly puzzling is the strong horizontal bias in the crossed-forearm conditions. In the case of tactile apparent motion, there seem to be no fixed priority rule for perceptual disambiguation. Rather the weighting of available evidence seems to depend on the degree of stimulus ambiguity, the current situation and on the perceptual

  17. Apparent place of Polaris and apparent Sidereal Time at 0 hour UT 1990-1994

    NASA Astrophysics Data System (ADS)

    1990-07-01

    The apparent right ascension and declination of Polaris and the Greenwich Sidereal Time at 0 hour Universal Time for each day is given. Tabulated apparent place coordinates are generated from the Fifth Fundamental Catalogue (FK5). Note that values for 1990 were previously published using the Fourth Fundamental Catalogue (FK4). Although values for apparent right ascension and declination of Polaris and Greenwich Sidereal Time differ between FK4 and FK5, the resulting differences in computed azimuth are small. The publication is prepared for the convenience of the surveyor who observes Polaris for azimuth control to orient a field survey project. The right ascension and declination values can be linearly interpolated directly from the tables using as an argument the decimal part (Universal Time converted to the decimal part of the day) of the Greenwich Civil Day (GCD).

  18. Spatial and temporal patterns of microearthquake frequency-magnitude distributions (b- values) within the axial region of the East Pacific Rise near 9-50 N

    NASA Astrophysics Data System (ADS)

    Bohnenstiehl, D. R.; Waldhauser, F.; Tolstoy, M.

    2007-12-01

    Relocated hypocentral data from a seven-month deployment of ocean bottom seismometers provides an opportunity to map microearthquake frequency-magnitude distributions (FMDs) along the 9 49-52 N region on the East Pacific Rise. These analyses, which incorporate more 9000 earthquakes, represent the first investigation of the 3-D spatial and temporal patterns of FMD's along any mid-ocean ridge spreading center. The data are well described by a Gutenberg-Richter model, indicating a power-law or fractal relationship between earthquake size and frequency. The scaling exponent, or b-value, shows significant spatial variability, exceeding a value of 2.0 at the shallowest depths (less than 0.5 km) on axis and dropping below 1.0 away from the axial trough. This spatial pattern is consistent with an inverse relationship between b-value and effective stress, with the lowest stress levels at shallow depths and relatively high stress levels (or low pore pressures) observed away from the hydrothermal cell. Intermediate b-values are observed in the 0.5-1.5 km depth range above the axial magma chamber; however, within this region significant variability also exists along axis. This heterogeneity suggests that the effective stress may vary at sub-kilometer scales within the hydrothermal reservoir. Although the rate of seismic activity increases by roughly a factor of three throughout the deployment (Oct. 2003-Apr. 2004), the frequency-magnitude distribution shows no temporal trend. As a by-product of this b- value analysis the detection capabilities of the array are assessed empirically in both space and time.

  19. Finding apparent horizons in numerical relativity

    NASA Astrophysics Data System (ADS)

    Thornburg, Jonathan

    1996-10-01

    We review various algorithms for finding apparent horizons in 3+1 numerical relativity. We then focus on one particular algorithm, in which we pose the apparent horizon equation H≡∇ini+Kijninj-K=0 as a nonlinear elliptic (boundary-value) PDE on angular-coordinate space for the horizon shape function r=h(θ,φ), finite difference this PDE, and use Newton's method or a variant to solve the finite difference equations. We describe a method for computing the Jacobian matrix of the finite differenced H(h) sH (sh) function by symbolically differentiating the finite difference equations, giving the Jacobian elements directly in terms of the finite difference molecule coefficients used in computing sH (sh). Assuming the finite differencing scheme commutes with linearization, we show how the Jacobian elements may be computed by first linearizing the continuum H(h) equations, then finite differencing the linearized continuum equations. (This is essentially just the ``Jacobian part'' of the Newton-Kantorovich method for solving nonlinear PDEs.) We tabulate the resulting Jacobian coefficients for a number of different sH (sh) and Jacobian computation schemes. We find this symbolic differentiation method of computing the Jacobian to be much more efficient than the usual numerical-perturbation method, and also much easier to implement than is commonly thought. When solving the discrete sH (sh)=0 equations, we find that Newton's method generally shows robust convergence. However, we find that it has a small (poor) radius of convergence if the initial guess for the horizon position contains significant high-spatial-frequency error components, i.e., angular Fourier components varying as (say) cosmθ with m>~8. (Such components occur naturally if spacetime contains significant amounts of high-frequency gravitational radiation.) We show that this poor convergence behavior is not an artifact of insufficient resolution in the finite difference grid; rather, it appears to be caused

  20. Apparent diamagnetic response of an inhomogeneous ferromagnet

    SciTech Connect

    Claus, H.; Veal, B.W.

    1997-07-01

    We present magnetization measurements on a weakly ferromagnetic Pd 0.5 at.{percent} Fe alloy (T{sub c}=15 K). Due to the preparation technique for the sample, it has a thin surface layer with slightly enhanced T{sub c}. In fields above 200 mG, the magnetization is typical of a ferromagnet. However, when cooling in very small fields ({ital H}{lt}25 mG), the magnetization reverses its direction at low temperatures, apparently becoming diamagnetic. The effect is very similar, but of opposite sign, to that observed in some high-T{sub c} superconducting samples where the magnetization becomes paramagnetic on field cooling (paramagnetic Meissner effect, PME). Whereas the origin of the PME in superconductors is controversial, the effect in our ferromagnetic sample is explained in terms of dipolar polarization of the interior of the sample by the surface layer with enhanced T{sub c}. Removing the surface layer eliminates this anomalous effect and the sample behaves like an ordinary ferromagnet, down to the lowest fields. {copyright} {ital 1997} {ital The American Physical Society}

  1. Apparent speed increases at low luminance

    PubMed Central

    Vaziri-Pashkam, Maryam; Cavanagh, Patrick

    2009-01-01

    To investigate the effect of luminance on apparent speed, subjects adjusted the speed of a low-luminance rotating grating (0.31 cd/m2) to match that of a high-luminance one (1260 cd/m2). Above 4 Hz, subjects overestimated the speed of the low-luminance grating. This overestimation increased as a function of temporal rate and reached 30% around 10 Hz temporal rates. The speed overestimation became significant once the lower luminance was 2.4 log units lower than the high luminance comparison. Next the role of motion smear in speed overestimation was examined. First it was shown that the length of the perceived motion smear increased at low luminances. Second, the length of the visible smear was manipulated by changing the presentation time of the stimuli. Speed overestimation was reduced at shorter presentation times. Third the speed of a blurred stimulus was compared to a stimulus with sharp edges and the blurred stimulus was judged to move faster. These results indicate that the length of motion smear following a target contributes to its perceived speed and that this leads to speed overestimation at low luminance where motion traces lengthen because of increased persistence. PMID:19146275

  2. Temporal changes in coda Q -1 and b value due to the static stress change associated with the 1995 Hyogo-ken Nanbu earthquake

    NASA Astrophysics Data System (ADS)

    Hiramatsu, Yoshihiro; Hayashi, Nobuhiko; Furumoto, Muneyoshi; Katao, Hiroshi

    2000-03-01

    The seismicity in the Tamba region, northeast of the Hyogo-ken Nanbu earthquake in Japan (January 17, 1995; MJMA 7.2), increased significantly following this earthquake. This increase suggests that the static stress change due to a large earthquake causes a change in the crustal condition or dynamics. In order to reveal the changes quantitatively, we investigate the temporal variation in coda Q-l and b value in the Tamba region. We analyze the waveform data of many shallow microearthquakes (M 1.5-3.0) in the region recorded in a period from 1987 to 1996. Coda Q-1 is estimated in 10 frequency bands in a range of 1.5-24 Hz based on the single isotropic scattering model. At frequencies between 1.5 and 4.0 Hz the temporal variation in coda Q-1 shows significant correlation with the occurrence of the Hyogo-ken Nanbu earthquake; coda Q-l increases after the event. A variation in b value whose sign is opposite to that of coda Q-1 is recognized. The fracture dimensions of microearthquakes that contribute to the variation in b value are estimated to be 400 m. This scale length is consistent with the characteristic scale length of scatterer, 300-600 m, which contributes effectively to a temporal variation in coda Q-1. The crustal activity in the Tamba region is possibly controlled by the heterogeneity with dominant scale of 102 m. The stress sensitivity of the coda Q-1 change is estimated to be 10 (MPa)-1. This value is an order of magnitude larger than the stress sensitivity of seismic velocity reported before.

  3. A feasibility study on monitoring the evolution of apparent diffusion coefficient decrease during thermal ablation

    PubMed Central

    Plata, Juan C.; Holbrook, Andrew B.; Marx, Michael; Salgaonkar, Vasant; Jones, Peter; Pascal-Tenorio, Aurea; Bouley, Donna; Diederich, Chris; Sommer, Graham; Pauly, Kim Butts

    2015-01-01

    Purpose: Evaluate whether a decrease in apparent diffusion coefficient (ADC), associated with loss of tissue viability (LOTV), can be observed during the course of thermal ablation of the prostate. Methods: Thermal ablation was performed in a healthy in vivo canine prostate model (N = 2, ages: 5 yr healthy, mixed breed, weights: 13–14 kg) using a transurethral high-intensity ultrasound catheter and was monitored using a strategy that interleaves diffusion weighted images and gradient-echo images. The two sequences were used to measure ADC and changes in temperature during the treatment. Changes in temperature were used to compute expected changes in ADC. The difference between expected and measured ADC, ADCDIFF, was analyzed in regions ranging from moderate hyperthermia to heat fixation. A receiver operator characteristic (ROC) curve analysis was used to select a threshold of detection of LOTV. Time of threshold activation, tLOTV, was compared with time to reach CEM43 = 240, tDOSE. Results: The observed relationship between temperature and ADC in vivo (2.2%/ °C, 1.94%–2.47%/ °C 95% confidence interval) was not significantly different than the previously reported value of 2.4%/ °C in phantom. ADCDIFF changes after correction for temperature showed a mean decrease of 25% in ADC 60 min post-treatment in regions where sufficient thermal dose (CEM43 > 240) was achieved. Following our ROC analysis, a threshold of 2.25% decrease in ADCDIFF for three consecutive time points was chosen as an indicator of LOTV. The ADCDIFF was found to decrease quickly (1–2 min) after reaching CEM43 = 240 in regions associated with heat fixation and more slowly (10–20 min) in regions that received slower heating. Conclusions: Simultaneous monitoring of ADC and temperature during treatment might allow for a more complete tissue viability assessment of ablative thermal treatments in the prostate. ADCDIFF decreases during the course of treatment may be interpreted as loss of

  4. High-frequency spectral falloff of earthquakes, fractal dimension of complex rupture, b value, and the scaling of strength on faults

    USGS Publications Warehouse

    Frankel, A.

    1991-01-01

    The high-frequency falloff ??-y of earthquake displacement spectra and the b value of aftershock sequences are attributed to the character of spatially varying strength along fault zones. I assume that the high frequency energy of a main shock is produced by a self-similar distribution of subevents, where the number of subevents with radii greater than R is proportional to R-D, D being the fractal dimension. In the model, an earthquake is composed of a hierarchical set of smaller earthquakes. The static stress drop is parameterized to be proportional to R??, and strength is assumed to be proportional to static stress drop. I find that a distribution of subevents with D = 2 and stress drop independent of seismic moment (?? = 0) produces a main shock with an ??-2 falloff, if the subevent areas fill the rupture area of the main shock. By equating subevents to "islands' of high stress of a random, self-similar stress field on a fault, I relate D to the scaling of strength on a fault, such that D = 2 - ??. Thus D = 2 corresponds to constant stress drop scaling (?? = 0) and scale-invariant fault strength. A self-similar model of aftershock rupture zones on a fault is used to determine the relationship between the b value, the size distribution of aftershock rupture zones, and the scaling of strength on a fault. -from Author

  5. Apparent lethal concentrations of pyrolysis products of some polymeric materials

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Marcussen, W. H.; Furst, A.; Kourtides, D. A.; Parker, J. A.

    1976-01-01

    Thirty-nine samples of polymeric materials were evaluated to determine the apparent lethal concentrations of their pyrolysis products. The materials were compared on the basis of the apparent lethal concentration for 50 percent of the test animals. Relative toxicity rankings based o apparent lethal concentration values can differ significantly depending on whether they are based on weight of sample charged or weight of sample pyrolyzed. The ranking of polyphenylene sulfide is particularly sensitive to this difference.

  6. Assessment of apparent diffusion coefficient values as predictor of aggressiveness in peripheral zone prostate cancer: comparison with Gleason score.

    PubMed

    Anwar, Shayan Sirat Maheen; Anwar Khan, Zahid; Shoaib Hamid, Rana; Haroon, Fahd; Sayani, Raza; Beg, Madiha; Khattak, Yasir Jamil

    2014-01-01

    Purpose. To determine association between apparent diffusion coefficient value on diffusion-weighted imaging and Gleason score in patients with prostate cancer. Methods. This retrospective case series was conducted at Radiology Department of Aga Khan University between June 2009 and June 2011. 28 patients with biopsy-proven prostate cancer were included who underwent ultrasound guided sextant prostate biopsy and MRI. MRI images were analyzed on diagnostic console and regions of interest were drawn. Data were entered and analyzed on SPSS 20.0. ADC values were compared with Gleason score using one-way ANOVA test. Results. In 28 patients, 168 quadrants were biopsied and 106 quadrants were positive for malignancy. 89 lesions with proven malignancy showed diffusion restriction. The mean ADC value for disease with a Gleason score of 6 was 935 mm(2)/s (SD = 248.4 mm(2)/s); Gleason score of 7 was 837 mm(2)/s (SD = 208.5 mm(2)/s); Gleason score of 8 was 614 mm(2)/s (SD = 108 mm(2)/s); and Gleason score of 9 was 571 mm(2)/s (SD = 82 mm(2)/s). Inverse relationship was observed between Gleason score and mean ADC values. Conclusion. DWI and specifically quantitative ADC values may help differentiate between low-risk (Gleason score, 6), intermediate-risk (Gleason score, 7), and high-risk (Gleason score 8 and 9) prostate cancers, indirectly determining the aggressiveness of the disease. PMID:24967293

  7. High b-Value Diffusion MRI to Differentiate Recurrent Tumors from Posttreatment Changes in Head and Neck Squamous Cell Carcinoma: A Single Center Prospective Study

    PubMed Central

    Acampora, Angela; Manzo, Gaetana; Fenza, Giacomo; Busto, Giuseppina; Serino, Antonietta; Manto, Andrea

    2016-01-01

    Recently DW-MR Imaging has shown promising results in distinguishing between recurrent tumors and posttreatment changes in Head and Neck Squamous Cell Carcinoma (HNSSC). Aim of this study was to evaluate the diagnostic performances of DWI at high b-value (b = 2000 s/mm2) compared to standard b-value (b = 1000 s/mm2) and ADCratio values (ADCratio = ADC2000/ADC1000 × 100) to differentiate recurrent tumors from posttreatment changes after treatment of HSNCC. 20 patients (16 M, 4 F) underwent MR Imaging between 2 and 16 months (mean 7) after treatment. Besides morphological sequences, we performed single-shot echo-planar DWI at b = 1000 s/mm2 and b = 2000 s/mm2, and corresponding ADC maps were generated (ADC1000 and ADC2000, resp.). By considering contrast-enhanced T1-weighted images as references, ROIs were drawn in order to evaluate mean ADC1000, ADC2000, and ADCratio. The mean ADC1000 and ADC2000 in recurrent tumors were significantly lower than those in posttreatment changes (P = 0.001 and P = 0.016, resp.). Moreover, the mean ADCratio between the two groups showed a statistically significant difference (P = 0.002). Sensitivity, specificity, and accuracy of ADCratio were 82.0%, 100%, and 90%, respectively, by considering an optimal cutoff value of 65.5%. ADCratio is a promising value to differentiate between recurrent tumors and posttreatment changes in HNSCC and may be more useful than ADC1000 and ADC2000. PMID:27376081

  8. Damage assessed by wavelet scale bands and b-value in dynamical tests of a reinforced concrete slab monitored with acoustic emission

    NASA Astrophysics Data System (ADS)

    Zitto, Miguel E.; Piotrkowski, Rosa; Gallego, Antolino; Sagasta, Francisco; Benavent-Climent, Amadeo

    2015-08-01

    The complex Morlet Continuous Wavelet Transform (CWT) was applied to acoustic emission (AE) signals from dynamic tests conducted on a reinforced concrete slab with a shaking table. The steel reinforcement bars did not yield during the tests, but a severe loss of bond between reinforcement bars and surrounding concrete was detected. Comparison of the evolution of the scale position of maximum values of CWT coefficients and the histories of response acceleration obtained in different seismic simulations allowed us to identify the (45-64 kHz) frequency band corresponding to the fracture of concrete. The Cumulative Acoustic Emission Energy (CAE) obtained by reconstructing the AE signals in this scale (frequency) band was compared with the Cumulative Dissipated Energy (CDE) of the tested structure. The CDE is accepted as a good parameter for characterizing the mechanical damage in structures. A reasonably good agreement was found between the normalized histories of CAE and CDE. This made it possible to categorize the cracking of concrete as the main source of damage in the reinforced concrete slab. Conversely, the differences between the CAE and CDE curves observed for high levels of peak acceleration applied to the shaking table can be attributed to the deformation of the steel that formed the columns. The AE coming from the plastic deformation of the steel is not detected by CAE due to the threshold amplitude (45 dB) used in the AE monitoring, but the strain energy dissipated by the steel through plastic deformations is included in the CDE. Further, a study of the evolution of the b-value in the successive seismic simulations revealed that the b-value can capture the inception of severe cracking in the concrete, which the tests described in this study attributed mainly to the loss of bond between reinforcing steel and surrounding concrete.

  9. Apparent-Strain Correction for Combined Thermal and Mechanical Testing

    NASA Technical Reports Server (NTRS)

    Johnson, Theodore F.; O'Neil, Teresa L.

    2007-01-01

    Combined thermal and mechanical testing requires that the total strain be corrected for the coefficient of thermal expansion mismatch between the strain gage and the specimen or apparent strain when the temperature varies while a mechanical load is being applied. Collecting data for an apparent strain test becomes problematic as the specimen size increases. If the test specimen cannot be placed in a variable temperature test chamber to generate apparent strain data with no mechanical loads, coupons can be used to generate the required data. The coupons, however, must have the same strain gage type, coefficient of thermal expansion, and constraints as the specimen to be useful. Obtaining apparent-strain data at temperatures lower than -320 F is challenging due to the difficulty to maintain steady-state and uniform temperatures on a given specimen. Equations to correct for apparent strain in a real-time fashion and data from apparent-strain tests for composite and metallic specimens over a temperature range from -450 F to +250 F are presented in this paper. Three approaches to extrapolate apparent-strain data from -320 F to -430 F are presented and compared to the measured apparent-strain data. The first two approaches use a subset of the apparent-strain curves between -320 F and 100 F to extrapolate to -430 F, while the third approach extrapolates the apparent-strain curve over the temperature range of -320 F to +250 F to -430 F. The first two approaches are superior to the third approach but the use of either of the first two approaches is contingent upon the degree of non-linearity of the apparent-strain curve.

  10. Apparent mass and cross-axis apparent mass of standing subjects during exposure to vertical whole-body vibration

    NASA Astrophysics Data System (ADS)

    Subashi, G. H. M. J.; Matsumoto, Y.; Griffin, M. J.

    2006-05-01

    The effects of posture and vibration magnitude on the vertical apparent mass and the fore-and-aft cross-axis apparent mass of the standing human body during exposure to vertical vibration have been investigated. Twelve male subjects were exposed to random vertical vibration over the frequency range 2.0-20 Hz at three vibration magnitudes: 0.125, 0.25 and 0.5 m s -2 rms. Subjects stood in five different postures: upright, lordotic, anterior lean, knees bent and knees more bent. The vertical acceleration at the floor and the forces in the vertical and fore-and-aft directions at the floor were used to obtain the apparent mass and the cross-axis apparent mass. The resonance frequency of the apparent mass was significantly reduced with knees bent and knees more bent postures, but there were only minor effects on the resonance frequency by changing the position of the upper body. Considerable cross-axis apparent mass, up to about 30% of the static mass of subjects, was found. The cross-axis apparent mass was influenced by all postural changes used in the study. In all postures the resonance frequencies of the apparent mass and the cross-axis apparent mass tended to decrease with increasing vibration magnitude. This nonlinear characteristic tended to be less clear in some postures in which subjects increased muscle tension.

  11. "Apparent Weight": A Concept that Is Confusing and Unnecessary

    ERIC Educational Resources Information Center

    Bartlett, Albert A.

    2010-01-01

    Two recent articles make prominent use of the concept of "apparent weight." The concept of "apparent weight" leads to two confusing inconsistencies. We need to know that with very little change in our representations, we can give our students an improved understanding of "weight" without ever having to invent the appealing but confusing concept of…

  12. 48 CFR 14.407-2 - Apparent clerical mistakes.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false Apparent clerical mistakes. 14.407-2 Section 14.407-2 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION CONTRACTING METHODS AND CONTRACT TYPES SEALED BIDDING Opening of Bids and Award of Contract 14.407-2 Apparent clerical mistakes. (a) Any...

  13. Multiple Weather Factors Affect Apparent Survival of European Passerine Birds

    PubMed Central

    Salewski, Volker; Hochachka, Wesley M.; Fiedler, Wolfgang

    2013-01-01

    Weather affects the demography of animals and thus climate change will cause local changes in demographic rates. In birds numerous studies have correlated demographic factors with weather but few of those examined variation in the impacts of weather in different seasons and, in the case of migrants, in different regions. Using capture-recapture models we correlated weather with apparent survival of seven passerine bird species with different migration strategies to assess the importance of selected facets of weather throughout the year on apparent survival. Contrary to our expectations weather experienced during the breeding season did not affect apparent survival of the target species. However, measures for winter severity were associated with apparent survival of a resident species, two short-distance/partial migrants and a long-distance migrant. Apparent survival of two short distance migrants as well as two long-distance migrants was further correlated with conditions experienced during the non-breeding season in Spain. Conditions in Africa had statistically significant but relatively minor effects on the apparent survival of the two long-distance migrants but also of a presumably short-distance migrant and a short-distance/partial migrant. In general several weather effects independently explained similar amounts of variation in apparent survival for the majority of species and single factors explained only relatively low amounts of temporal variation of apparent survival. Although the directions of the effects on apparent survival mostly met our expectations and there are clear predictions for effects of future climate we caution against simple extrapolations of present conditions to predict future population dynamics. Not only did weather explains limited amounts of variation in apparent survival, but future demographics will likely be affected by changing interspecific interactions, opposing effects of weather in different seasons, and the potential for

  14. Seismic imaging of the 2001 Bhuj Mw7.7 earthquake source zone: b-value, fractal dimension and seismic velocity tomography studies

    NASA Astrophysics Data System (ADS)

    Mandal, Prantik; Rodkin, Mikhail V.

    2011-11-01

    We use precisely located aftershocks of the 2001 Mw7.7 Bhuj earthquake (2001-2009) to explore the structure of the Kachchh seismic zone by mapping the 3-D distributions of b-value, fractal dimension (D) and seismic velocities. From frequency-magnitude analysis, we find that the catalog is complete above Mw = 3.0. Thus, we analyze 2159 aftershocks with Mw ≥ 3.0 to estimate the 3-D distribution of b-value and fractal dimensions using maximum-likelihood and spatial correlation dimension approaches, respectively. Our results show an area of high b-, D- and Vp/Vs ratio values at 15-35 km depth in the main rupture zone (MRZ), while relatively low b- and D values characterize the surrounding rigid regions and Gedi fault (GF) zone. We propose that higher material heterogeneities in the vicinity of the MRZ and/or circulation of deep aqueous fluid/volatile CO 2 is the main cause of the increased b-, D- and Vp/Vs ratio values at 15-35 km depth. Seismic velocity images also show some low velocity zones continuing in to the deep lower crust, supporting the existence of circulation of deep aqueous fluid / volatile CO 2 in the region (probably released from the eclogitasation of olivine rich lower crustal rocks). The presence of number of high and low velocity patches further reveals the heterogeneous and fractured nature of the MRZ. Interestingly, we observe that Aki (1981)'s relation (D = 2b) is not valid for the spatial b-D correlation of the events in the GF (D 2 = 1.2b) zone. However, the events in the MRZ (D 2 = 1.7b) show a fair agreement with the D = 2b relationship while the earthquakes associated with the remaining parts of the aftershock zone (D 2 = 1.95b) show a strong correlation with the Aki (1981)'s relationship. Thus, we infer that the remaining parts of the aftershock zone are probably behaving like locked un-ruptured zones, where larger stresses accumulate. We also propose that deep fluid involvement may play a key role in generating seismic activity in the

  15. Evolution of Apparent Diffusion Coefficient and Fractional Anisotropy in the Cerebrum of Asphyxiated Newborns Treated with Hypothermia over the First Month of Life.

    PubMed

    Kwan, Saskia; Boudes, Elodie; Benseler, Anouk; Gilbert, Guillaume; Saint-Martin, Christine; Shevell, Michael; Wintermark, Pia

    2015-01-01

    The objective of this study was to assess the evolution of diffusion-weighted imaging (DWI) and diffusion-tensor imaging (DTI) over the first month of life in asphyxiated newborns treated with hypothermia and to compare it with that of healthy newborns. Asphyxiated newborns treated with hypothermia were enrolled prospectively; and the presence and extent of brain injury were scored on each MRI. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured in the basal ganglia, in the white matter and in the cortical grey matter. Sixty-one asphyxiated newborns treated with hypothermia had a total of 126 ADC and FA maps. Asphyxiated newborns developing brain injury eventually had significantly decreased ADC values on days 2-3 of life and decreased FA values around day 10 and 1 month of life compared with those not developing brain injury. Despite hypothermia treatment, asphyxiated newborns may develop brain injury that still can be detected with advanced neuroimaging techniques such as DWI and DTI as early as days 2-3 of life. A study of ADC and FA values over time may aid in the understanding of how brain injury develops in these newborns despite hypothermia treatment. PMID:26229690

  16. Mapping of b-values, earthquake relocation, and Coulomb stress changes during 1992-2007 in the Murindó seismic zone, Colombia

    NASA Astrophysics Data System (ADS)

    Dionicio, Viviana; Sánchez, John J.

    2012-07-01

    Seismicity in the Murindó seismic zone, Colombia (6° to 8° and - 75.5° to - 78.0°) during 1992-2007 included the occurrence of the M W 6.6 foreshock on October 17, and M W 7.1 mainshock on October 18, 1992, and aftershocks, which caused severe damage throughout the region. We modeled this seismic sequence by means of Coulomb stress changes imparted by slip along two semi-vertical fault planes with left-lateral motion and subdivided slip. Seismicity thereafter (1993-2007) was characterized by earthquakes magnitude in the range 0.7-6.1 for which a magnitude of completeness M C = 2.7 was determined. b-values are relatively high to the south of the study region and relatively low to the north and northwest. The relocation of epicenters indicates that recent seismicity may be occurring on a fault that is yet to be mapped under the Atrato river valley. We conclude that the 1992 seismic sequence was a case of a major earthquake facilitated by the stress changes imparted during a strong rupture the previous day and that the aftershocks and background seismicity in the region can be explained by static Coulomb stress changes up to 50.1 bar. Our results have implications for hazard in Colombia and serve as basis to foster future investigations.

  17. 48 CFR 14.407-2 - Apparent clerical mistakes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... clerical mistakes. (a) Any clerical mistake, apparent on its face in the bid, may be corrected by the... bid and a copy of the verification to the duplicate bid. Correction shall not be made on the face...

  18. Apparent Ionic Charge in Electrolyte and Polyelectrolyte Solutions

    ERIC Educational Resources Information Center

    Magdelenat, H.; And Others

    1978-01-01

    Compares average displacements of charged particles under thermal motion alone with those obtained by the action of an external electric field to develop a concept of "apparent charge" to approximate actual structural charge in an electrolyte solution. (SL)

  19. An Improved Comprehensive Model for the Apparent Viscosity of Blood

    NASA Astrophysics Data System (ADS)

    Jacobitz, Frank; Anderson, Spencer

    2008-11-01

    An improved comprehensive model for the apparent viscosity of blood is developed and used in simulations of the microcirculation in capillary bundles of rat spinotrapezius muscle fascia. In the microcirculation, the apparent viscosity of blood depends on the local vessel diameter, hematocrit, and shear rate. The proposed comprehensive model extends the apparent viscosity model developed by Pries, Secomb, Gaehtgens, and Gross (Circulation Research, 67, 826-834, 1990), which describes the effect of vessel diameter and hematocrit on the apparent viscosity. A shear thinning term is developed using the experimental data of Lipowsky, Usami, and Chien (Microvascular Research, 19, 297-319, 1980). Curve fits of this data can be combined with equations given in the Pries et al. work to create a system of equations that can be used to find the shear thinning factor. The simulations based on the improved apparent viscosity model use realistic vessel topology for the microvasculature, reconstructed from microscope images of tissue samples, and consider passive and active vessel properties. The numerical method is based on a Hagen-Poiseuille balance in the microvessels and a sparse matrix solver is used to obtain the solution. It was found that the inclusion of the shear factor decreases the overall flowrate in the capillary bundle. Many vessel connections in the fascia are characterized by relatively low shear rates and therefore increased apparent viscosity.

  20. Apparent Diffusion Coefficient Predicts Pathology Complete Response of Rectal Cancer Treated with Neoadjuvant Chemoradiotherapy

    PubMed Central

    Chen, Yuan-Gui; Chen, Ming-Qiu; Guo, Yu-Yan; Li, Si-Cong; Wu, Jun-Xin; Xu, Ben-Hua

    2016-01-01

    Objective To evaluate the predictive value of the apparent diffusion coefficient (ADC) for pathologic complete response (pCR) to neoadjuvant chemoradiotherapy (NCRT) in locally advanced rectal cancer. Methods A total of 265 patients with rectal adenocarcinoma, whole Diffusion-Weighted MRI (DWI-MRI) images, clinically stage II to III (cT3-4 and/or cN+) and treated with NCRT followed by TME were screened. Fifty patients with pCR and another 50 patients without pCR with similar clinical charcacters and treatment regimens were selected for statistical analysis. All the patients’ pre-CRT and post-CRT average ADC values were calculated from the coefficient maps created by DWI-MRI and recorded independently. The difference in the ADC values between the pCR and non-pCR was analyzed by the Mann-Whitney U test. The cut-off ADC value of the receiver operating characteristic (ROC) curve with pCR was then established. Results The mean pre- and post-ADC values in all patients, and in pCR patients and non-pCR patients were 0.879±0.06 and 1.383±0.11, 0.859±0.04 and 1.440±0.10, 0.899±0.07 and 1.325±0.09 (×10-3mm2/s), respectively. The difference between the pre- and post-ADC values in all patients, pCR patients, and non-pCR patients were considered to be statistically significant. The pre-ADC value was significantly lower in the pCR patients than in the non-pCR patients (p = 0.003), whereas the post-ADC values were significantly higher in the pCR patients than in the non-pCR patients. The percentage increase of the ADC value (ΔADC%) in the pCR and non-pCR patients were 68% and 48% respectively (p<0.001). The ROC curves of the cut-off value of the pre-CRT patient ADC value was 0.866×10-3mm2/s. The AUC, sensitivity, specificity, PPV, NPV, and accuracy of diagnosing pCR were 0.670 (95% CI 0.563–0.777), 0.600, 0.640, 60%, 60%, and 60%, respectively. The cut-off value of ΔADC% was 58%. The corresponding AUC, sensitivity, specificity, PPV, NPV, and accuracy of diagnosing p

  1. EFFECT OF PRESSURE ON THE APPARENT SPECIFIC VOLUME OF PROTEINS*

    PubMed Central

    Fahey, Paul F.; Kupke, D. W.; Beams, J. W.

    1969-01-01

    The magnetic densimeter has been employed to measure the densities and apparent specific volumes of certain proteins in aqueous solutions as a function of pressure. The method gave values in satisfactory agreement with those found in the literature for aqueous electrolyte solutions. A change in apparent specific volume of the monomeric proteins, ribonuclease and turnip yellow mosaic virus and its capsid protein, at pressures up to 400 atmospheres at 20°C was not observed within the precision of the measurements. Also, no change in the apparent specific volume of tobacco mosaic virus protein was observed as a function of these pressures whether the protein was predominantly in the polymerized or unpolymerized state. The magnetic densimeter was found to be a convenient instrument for measuring compressibilities of very small samples of solutions. PMID:5257142

  2. Apparent Stress and Centroid Time Shift: Oceanic vs Continental Earthquakes

    NASA Astrophysics Data System (ADS)

    Pérez-Campos, X.; McGuire, J. J.; Beroza, G. C.

    2001-12-01

    Seismic energy is a broadband measure of the strength of radiation in an earthquake. Slow earthquakes, for which the rupture velocity and/or the rise time, are longer than usual, are characterized by having anomalously little seismic radiation at high frequencies. Thus, the apparent stress, the ratio of the seismic energy to the seismic moment times the shear modulus, is a natural measure of whether or not an earthquake is slow. Slow events have long been associated with oceanic tranforms. It is unusual then, that in a global study of strike slip earthquakes, Choy and Boatwright (1995) found that oceanic transform events have values of apparent stress approximately an order of magnitude higher than normal and reverse faulting events. Part of this discrepancy appears to be a selection bias in that some slow events that are deficient in high frequency energy are not routinely reported by the NEIC. We find that the average apparent stress for oceanic ridge-ridge transform events is lower than for continental strike-slip events. Another possible measure of whether or not an earthquake is slow is the centroid time shift. We find a population of slow events on oceanic transforms with both a very low apparent stress and a very large centroid time shift, as might be expected. Continental transform events that have similarly low apparent stress do not show the same correlation with centroid time shift. It is not clear why these two populations differ, but by comparing spectra for different events with low apparent stress but different centroid time shift, we should be able to test possible sources of the differences, such as variations in the spectral shape for continental versus oceanic events, that could explain these observations.

  3. On apparent temperature in low-frequency Alfvenic turbulence

    SciTech Connect

    Nariyuki, Yasuhiro

    2012-08-15

    Low-frequency, parallel propagating Alfvenic turbulence in collisionless plasmas is theoretically studied. Alfvenic turbulence is derived as an equilibrium state (Beltrami field) in the magnetohydrodynamic equations with the pressure anisotropy and multi-species of ions. It is shown that the conservation of the total 'apparent temperature' corresponds to the Bernoulli law. A simple model of the radially expanding solar wind including Alfvenic turbulence is also discussed. The conversion of the wave energy in the 'apparent temperature' into the 'real temperature' is facilitated with increasing radial distance.

  4. General theory for apparent energy distribution of sea waves

    NASA Astrophysics Data System (ADS)

    Wu, Ke-Jian; Sun, Fu

    1997-12-01

    This paper presents a general theory for the apparent energy distribution of sea waves. Using the joint distribution of wave periods and heights proposed earlier by the second author, the authors define the generalized apparent energy distribution and derive the analytical form of the so called generalized outer frequency spectrum or nth-order frequency spectrum. Some possible relationships between it and the Fourier frequency spectrum are discussed. It is shown that the widely used Bretschneider spectrum can be easily obtained from the above definition and that generalized outer frequency spectrum has equilibrium range with exponent -( n+3) whose upper limit is -3.

  5. Surgical treatment for apparent early stage endometrial cancer

    PubMed Central

    2014-01-01

    Most experts would agree that the standard surgical treatment for endometrial cancer includes a hysterectomy and bilateral salpingo-oophorectomy; however, the benefit of full surgical staging with lymph node dissection in patients with apparent early stage disease remains a topic of debate. Recent prospective data and advances in laparoscopic techniques have transformed this disease into one that can be successfully managed with minimally invasive surgery. This review will discuss the current surgical management of apparent early stage endometrial cancer and some of the new techniques that are being incorporated. PMID:24596812

  6. Bias of apparent tracer ages in heterogeneous environments.

    PubMed

    McCallum, James L; Cook, Peter G; Simmons, Craig T; Werner, Adrian D

    2014-01-01

    The interpretation of apparent ages often assumes that a water sample is composed of a single age. In heterogeneous aquifers, apparent ages estimated with environmental tracer methods do not reflect mean water ages because of the mixing of waters from many flow paths with different ages. This is due to nonlinear variations in atmospheric concentrations of the tracer with time resulting in biases of mixed concentrations used to determine apparent ages. The bias of these methods is rarely reported and has not been systematically evaluated in heterogeneous settings. We simulate residence time distributions (RTDs) and environmental tracers CFCs, SF6 , (85) Kr, and (39) Ar in synthetic heterogeneous confined aquifers and compare apparent ages to mean ages. Heterogeneity was simulated as both K-field variance (σ(2) ) and structure. We demonstrate that an increase in heterogeneity (increase in σ(2) or structure) results in an increase in the width of the RTD. In low heterogeneity cases, widths were generally on the order of 10 years and biases generally less than 10%. In high heterogeneity cases, widths can reach 100 s of years and biases can reach up to 100%. In cases where the temporal variations of atmospheric concentration of individual tracers vary, different patterns of bias are observed for the same mean age. We show that CFC-12 and CFC-113 ages may be used to correct for the mean age if analytical errors are small. PMID:23550995

  7. 20 CFR 653.113 - Processing apparent violations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false Processing apparent violations. 653.113 Section 653.113 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR SERVICES OF THE EMPLOYMENT SERVICE SYSTEM Services for Migrant and Seasonal Farmworkers (MSFWs) §...

  8. 20 CFR 653.113 - Processing apparent violations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Processing apparent violations. 653.113 Section 653.113 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR SERVICES OF THE EMPLOYMENT SERVICE SYSTEM Services for Migrant and Seasonal Farmworkers (MSFWs) §...

  9. Apparent horizons in D-dimensional Robinson-Trautman spacetime

    SciTech Connect

    Svitek, Otakar

    2009-05-01

    We derive the higher dimensional generalization of Penrose-Tod equation describing apparent horizons in Robinson-Trautman spacetimes. New results concerning the existence and uniqueness of its solutions in four dimensions are proven. Namely, previous results of Tod [1] are generalized to nonvanishing cosmological constant.

  10. The horizontal apparent mass of the standing human body

    NASA Astrophysics Data System (ADS)

    Matsumoto, Y.; Griffin, M. J.

    2011-06-01

    The driving-point dynamic responses of standing people (e.g. their mechanical impedance or apparent mass) influence their dynamic interactions with structures on which they are supported. The apparent mass of the standing body has been reported previously for vertical excitation but not for lateral or fore-and-aft excitation. Twelve standing male subjects were exposed to fore-and-aft and lateral random vibration over the frequency range 0.1-5.0 Hz for 180 s at four vibration magnitudes: 0.016, 0.0315, 0.063, and 0.125 m s -2 rms. With lateral excitation at 0.063 m s -2 rms, subjects also stood with three separations of the feet. The dynamic forces measured at the driving-point in each of the three translational axes (i.e. fore-and-aft, lateral and vertical) showed components not linearly related to the input vibration, and not seen in previous studies with standing subjects exposed to vertical vibration or seated subjects exposed to vertical or horizontal vibration. A principal peak in the lateral apparent mass around 0.5 Hz tended to decrease in both frequency and magnitude with increasing magnitude of vibration and increase with increasing separation of the feet. The fore-and-aft apparent mass appeared to peak at a frequency lower than the lowest frequency used in the study.

  11. Increasing Range Of Apparent Depth In A Stereoscopic Display

    NASA Technical Reports Server (NTRS)

    Busquets, Anthony M.; Parrish, Russell V.; Williams, Steven P.

    1995-01-01

    Optical configuration conceived for increasing range of apparent depth provided by stereoscopic display system, without imposing concomitant reduction in field of view. Observer wears shuttered goggles synchronized with alternating left- and right-eye views on display. However, instead of looking directly at display screen, observer looks at screen via reflection in mirror collimating light emitted by screen.

  12. Discovery of an Apparent Nova in M81

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Alfaro, M. Diaz; Ordonez-Etxeberria, I.; Vaduvescu, O.

    2015-01-01

    We report the discovery of an apparent nova in M81 on a co-added 1600-s narrow-band H-alpha CCD image taken with the 2.5-m Isaac Newton Telescope (INT) + WFC at La Palma under ~2.4" seeing on 2015 Jan. 15.126 UT.

  13. Spatial Attention and Audiovisual Interactions in Apparent Motion

    ERIC Educational Resources Information Center

    Sanabria, Daniel; Soto-Faraco, Salvador; Spence, Charles

    2007-01-01

    In this study, the authors combined the cross-modal dynamic capture task (involving the horizontal apparent movement of visual and auditory stimuli) with spatial cuing in the vertical dimension to investigate the role of spatial attention in cross-modal interactions during motion perception. Spatial attention was manipulated endogenously, either…

  14. Changes in apparent duration follow shifts in perceptual timing.

    PubMed

    Bruno, Aurelio; Ayhan, Inci; Johnston, Alan

    2015-01-01

    It is well established that the apparent duration of moving visual objects is greater at higher as compared to slower speeds. Here we report the effects of acceleration and deceleration on the perceived duration of a drifting grating with average speed kept constant (10°/s).For acceleration, increasing the speed range progressively reduced percei