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Sample records for perfusion weighted mri

  1. 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.

  2. Perfusion MRI: The Five Most Frequently Asked Clinical Questions

    PubMed Central

    Essig, Marco; Nguyen, Thanh Binh; Shiroishi, Mark S.; Saake, Marc; Provenzale, James M.; Enterline, David S.; Anzalone, Nicoletta; Dörfler, Arnd; Rovira, Àlex; Wintermark, Max; Law, Meng

    2013-01-01

    OBJECTIVE This article addresses questions that radiologists frequently ask when planning, performing, processing, and interpreting MRI perfusion studies in CNS imaging. CONCLUSION Perfusion MRI is a promising tool in assessing stroke, brain tumors, and neurodegenerative diseases. Most of the impediments that have limited the use of perfusion MRI can be overcome to allow integration of these methods into modern neuroimaging protocols. PMID:23971482

  3. Perfusion MRI: The Five Most Frequently Asked Technical Questions

    PubMed Central

    Essig, Marco; Shiroishi, Mark S.; Nguyen, Thanh Binh; Saake, Marc; Provenzale, James M.; Enterline, David; Anzalone, Nicoletta; Dörfler, Arnd; Rovira, Àlex; Wintermark, Max; Law, Meng

    2013-01-01

    OBJECTIVE This and its companion article address the 10 most frequently asked questions that radiologists face when planning, performing, processing, and interpreting different MR perfusion studies in CNS imaging. CONCLUSION Perfusion MRI is a promising tool in assessing stroke, brain tumors, and patients with neurodegenerative diseases. Most of the impediments that have limited the use of perfusion MRI can be overcome to allow integration of these methods into modern neuroimaging protocols. PMID:23255738

  4. Technical Pitfalls of Signal Truncation in Perfusion MRI of Glioblastoma.

    PubMed

    Wong, Kelvin K; Fung, Steve H; New, Pamela Z; Wong, Stephen T C

    2016-01-01

    Dynamic susceptibility contrast (DSC) perfusion-weighted imaging (PWI) is widely used in clinical settings for the radiological diagnosis of brain tumor. The signal change in brain tissue in gradient echo-based DSC PWI is much higher than in spin echo-based DSC PWI. Due to its exquisite sensitivity, gradient echo-based sequence is the preferred method for imaging of all tumors except those near the base of the skull. However, high sensitivity also comes with a dynamic range problem. It is not unusual for blood volume to increase in gene-mediated cytotoxic immunotherapy-treated glioblastoma patients. The increase of fractional blood volume sometimes saturates the MRI signal during first-pass contrast bolus arrival and presents signal truncation artifacts of various degrees in the tumor when a significant amount of blood exists in the image pixels. It presents a hidden challenge in PWI, as this signal floor can be either close to noise level or just above and can go no lower. This signal truncation in the signal intensity time course is a significant issue that deserves attention in DSC PWI. In this paper, we demonstrate that relative cerebral blood volume and relative cerebral blood flow (rCBF) are underestimated due to signal truncation in DSC perfusion, in glioblastoma patients. We propose the use of second-pass tissue residue function in rCBF calculation using least-absolute-deviation deconvolution to avoid the underestimation problem.

  5. Technical Pitfalls of Signal Truncation in Perfusion MRI of Glioblastoma

    PubMed Central

    Wong, Kelvin K.; Fung, Steve H.; New, Pamela Z.; Wong, Stephen T. C.

    2016-01-01

    Dynamic susceptibility contrast (DSC) perfusion-weighted imaging (PWI) is widely used in clinical settings for the radiological diagnosis of brain tumor. The signal change in brain tissue in gradient echo-based DSC PWI is much higher than in spin echo-based DSC PWI. Due to its exquisite sensitivity, gradient echo-based sequence is the preferred method for imaging of all tumors except those near the base of the skull. However, high sensitivity also comes with a dynamic range problem. It is not unusual for blood volume to increase in gene-mediated cytotoxic immunotherapy-treated glioblastoma patients. The increase of fractional blood volume sometimes saturates the MRI signal during first-pass contrast bolus arrival and presents signal truncation artifacts of various degrees in the tumor when a significant amount of blood exists in the image pixels. It presents a hidden challenge in PWI, as this signal floor can be either close to noise level or just above and can go no lower. This signal truncation in the signal intensity time course is a significant issue that deserves attention in DSC PWI. In this paper, we demonstrate that relative cerebral blood volume and relative cerebral blood flow (rCBF) are underestimated due to signal truncation in DSC perfusion, in glioblastoma patients. We propose the use of second-pass tissue residue function in rCBF calculation using least-absolute-deviation deconvolution to avoid the underestimation problem. PMID:27531989

  6. UMMPerfusion: an open source software tool towards quantitative MRI perfusion analysis in clinical routine.

    PubMed

    Zöllner, Frank G; Weisser, Gerald; Reich, Marcel; Kaiser, Sven; Schoenberg, Stefan O; Sourbron, Steven P; Schad, Lothar R

    2013-04-01

    To develop a generic Open Source MRI perfusion analysis tool for quantitative parameter mapping to be used in a clinical workflow and methods for quality management of perfusion data. We implemented a classic, pixel-by-pixel deconvolution approach to quantify T1-weighted contrast-enhanced dynamic MR imaging (DCE-MRI) perfusion data as an OsiriX plug-in. It features parallel computing capabilities and an automated reporting scheme for quality management. Furthermore, by our implementation design, it could be easily extendable to other perfusion algorithms. Obtained results are saved as DICOM objects and directly added to the patient study. The plug-in was evaluated on ten MR perfusion data sets of the prostate and a calibration data set by comparing obtained parametric maps (plasma flow, volume of distribution, and mean transit time) to a widely used reference implementation in IDL. For all data, parametric maps could be calculated and the plug-in worked correctly and stable. On average, a deviation of 0.032 ± 0.02 ml/100 ml/min for the plasma flow, 0.004 ± 0.0007 ml/100 ml for the volume of distribution, and 0.037 ± 0.03 s for the mean transit time between our implementation and a reference implementation was observed. By using computer hardware with eight CPU cores, calculation time could be reduced by a factor of 2.5. We developed successfully an Open Source OsiriX plug-in for T1-DCE-MRI perfusion analysis in a routine quality managed clinical environment. Using model-free deconvolution, it allows for perfusion analysis in various clinical applications. By our plug-in, information about measured physiological processes can be obtained and transferred into clinical practice.

  7. Relationship between diffusion parameters derived from intravoxel incoherent motion MRI and perfusion measured by dynamic contrast-enhanced MRI of soft tissue tumors.

    PubMed

    Marzi, Simona; Stefanetti, Linda; Sperati, Francesca; Anelli, Vincenzo

    2016-01-01

    Our aim was to evaluate the link between diffusion parameters measured by intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) and the perfusion metrics obtained with dynamic contrast-enhanced (DCE) MRI in soft tissue tumors (STTs). Twenty-eight patients affected by histopathologically confirmed STT were included in a prospective study. All patients underwent both DCE MRI and IVIM DWI. The perfusion fraction f, diffusion coefficient D and perfusion-related diffusion coefficient D* were estimated using a bi-exponential function to fit the DWI data. DCE MRI was acquired with a temporal resolution of 3-5 s. Maps of the initial area under the gadolinium concentration curve (IAUGC), time to peak (TTP) and maximum slope of increase (MSI) were derived using commercial software. The relationships between the DCE MRI and IVIM DWI measurements were assessed by Spearman's test. To exclude false positive results under multiple testing, the false discovery rate (FDR) procedure was applied. The Mann-Whitney test was used to evaluate the differences between all variables in patients with non-myxoid and myxoid STT. No significant relationship was found between IVIM parameters and any DCE MRI parameters. Higher f and D*f values were found in non-myxoid tumors compared with myxoid tumors (p = 0.004 and p = 0.003, respectively). MSI was significantly higher in non-myxoid tumors than in myxoid tumors (p = 0.029). From the visual assessments of single clinical cases, both f and D*f maps were in satisfactory agreement with DCE maps in the extreme cases of an avascular mass and a highly vascularized mass, whereas, for tumors with slight vascularity or with a highly heterogeneous perfusion pattern, this association was not straightforward. Although IVIM DWI was demonstrated to be feasible in STT, our data did not support evident relationships between perfusion-related IVIM parameters and perfusion measured by DCE MRI.

  8. Diagnostic Performance of Dual-Energy CT Stress Myocardial Perfusion Imaging: Direct Comparison With Cardiovascular MRI

    PubMed Central

    Ko, Sung Min; Song, Meong Gun; Chee, Hyun Kun; Hwang, Hweung Kon; Feuchtner, Gudrun Maria; Min, James K.

    2014-01-01

    OBJECTIVE The purpose of this study was to assess the diagnostic performance of stress perfusion dual-energy CT (DECT) and its incremental value when used with coronary CT angiography (CTA) for identifying hemodynamically significant coronary artery disease. SUBJECTS AND METHODS One hundred patients with suspected or known coronary artery disease without chronic myocardial infarction detected with coronary CTA underwent stress perfusion DECT, stress cardiovascular perfusion MRI, and invasive coronary angiography (ICA). Stress perfusion DECT and cardiovascular stress perfusion MR images were used for detecting perfusion defects. Coronary CTA and ICA were evaluated in the detection of ≥ 50% coronary stenosis. The diagnostic performance of coronary CTA for detecting hemodynamically significant stenosis was assessed before and after stress perfusion DECT on a pervessel basis with ICA and cardiovascular stress perfusion MRI as the reference standard. RESULTS The performance of stress perfusion DECT compared with cardiovascular stress perfusion MRI on a per-vessel basis in the detection of perfusion defects was sensitivity, 89%; specificity, 74%; positive predictive value, 73%; negative predictive value, 90%. Per segment, these values were sensitivity, 76%; specificity, 80%; positive predictive value, 63%; and negative predictive value, 88%. Compared with ICA and cardiovascular stress perfusion MRI per vessel territory the sensitivity, specificity, positive predictive value, and negative predictive value of coronary CTA were 95%, 61%, 61%, and 95%. The values for stress perfusion DECT were 92%, 72%, 68%, and 94%. The values for coronary CTA and stress perfusion DECT were 88%, 79%, 73%, and 91%. The ROC AUC increased from 0.78 to 0.84 (p = 0.02) with the use of coronary CTA and stress perfusion DECT compared with coronary CTA alone. CONCLUSION Stress perfusion DECT plays a complementary role in enhancing the accuracy of coronary CTA for identifying hemodynamically

  9. Tracer kinetic modelling in MRI: estimating perfusion and capillary permeability

    NASA Astrophysics Data System (ADS)

    Sourbron, S. P.; Buckley, D. L.

    2012-01-01

    The tracer-kinetic models developed in the early 1990s for dynamic contrast-enhanced MRI (DCE-MRI) have since become a standard in numerous applications. At the same time, the development of MRI hardware has led to increases in image quality and temporal resolution that reveal the limitations of the early models. This in turn has stimulated an interest in the development and application of a second generation of modelling approaches. They are designed to overcome these limitations and produce additional and more accurate information on tissue status. In particular, models of the second generation enable separate estimates of perfusion and capillary permeability rather than a single parameter Ktrans that represents a combination of the two. A variety of such models has been proposed in the literature, and development in the field has been constrained by a lack of transparency regarding terminology, notations and physiological assumptions. In this review, we provide an overview of these models in a manner that is both physically intuitive and mathematically rigourous. All are derived from common first principles, using concepts and notations from general tracer-kinetic theory. Explicit links to their historical origins are included to allow for a transfer of experience obtained in other fields (PET, SPECT, CT). A classification is presented that reveals the links between all models, and with the models of the first generation. Detailed formulae for all solutions are provided to facilitate implementation. Our aim is to encourage the application of these tools to DCE-MRI by offering researchers a clearer understanding of their assumptions and requirements.

  10. Perfusion weighted imaging in the assessment of the pathology and outcomes of lateral medullary infarction

    PubMed Central

    Zhang, Dao P.; Zhang, Hong T.; Yin, Suo; Yan, Fu L.

    2016-01-01

    This series case report aimed to elucidate the underlying pathology and outcomes of lateral medullary infarction (LMI) using perfusion weighted imaging (PWI). Four patients were diagnosed with LMI based on high-field diffusion-weighted magnetic resonance imaging (MRI-DWI) and PWI. The national institutes of health stroke scale (NIHSS) scores were recorded on days 1, 7, and 30, and the Barthel index was assessed on days 7 and 30. Three patients exhibited relative regional hypoperfusion of medullary lesion in the perfusion maps. Two cases exhibited ipsilateral hypoperfusion in the inferior cerebellum, whereas one patient exhibited a relatively regional hyperperfusion in the medulla oblongata. The LMI patients with a high NIHSS score and low Barthel index on days 7 and 30 exhibited regional hypoperfusion. This report of 4 LMI cases provides preliminary evidence that regional hypoperfusion may contribute to worse outcomes in LMI. PMID:27744467

  11. A study on cerebral hemodynamic analysis of moyamoya disease by using perfusion MRI

    NASA Astrophysics Data System (ADS)

    Dong, Kyung-Rae; Goo, Eun-Hoe; Lee, Jae-Seung; Chung, Woon-Kwan

    2013-10-01

    This study examined the clinical applications of perfusion magnetic resonance imaging (MRI) in patients with moyamoya disease (MMD). Twenty-two patients with moyamoya disease (9 men and 13 women) with a mean age of 9.3 years (range: 4-22 years) were enrolled in this study. Perfusion MRI was performed by scanning the patients7.5 cm upward from the base of the cerebellum before their being process for post-treatment. The scan led to the acquisition of the following four map images: the cerebral blood volume (CBV), the cerebral blood flow (CBF), the mean transit time (MTT) for the contrast medium, and the time to peak (TTP) for the contrast medium. The lesions were assessed using the CBV, the CBF, the MTT and the TTP maps of perfusion MRI; the MTT and the TTP were measured in the lesion areas, as well as in the normal and the symmetric areas. Perfusion defects were recognizable in all four perfusion MRI maps, and the MTT and the TTP showed a conspicuous delay in the parts where perfusion defects were recognized. The MTT and the TTP images of perfusion MRI reflected a significant correlation between the degrees of stenosis and occlusion in the posterior cerebral artery (PCA), as well as the development of collateral vessels. The four perfusion MRI maps could be used to predict the degrees of stenosis and occlusion in the posterior circulation, as well as the development of the collateral vessels, which enabled a hemodynamic evaluation of the parts with perfusion defects. Overall, perfusion MRI is useful for the diagnosis and the treatment of moyamoya disease and can be applied to clinical practice.

  12. [An evaluation of ischemic stroke using dynamic contrast enhanced perfusion MRI].

    PubMed

    Yamaguchi, H; Igarashi, H; Katayama, Y; Terashi, A

    1998-04-01

    Thrombolytic therapy during the hyperacute stage is important for salvaging dying cerebral tissue. To date, however, accurate non-invasive assessment of an ischemic lesion during the hyperacute stage has not been possible. Perfusion MRI may be the key to the quick diagnosis of ischemic lesions. To assess the feasibility of dynamic contrast enhanced perfusion MRI, echo planar imaging was performed in 10 patients with ischemic stroke. The relative cerebral blood volume (rCBV), mean transit time (MTT), and relative cerebral blood flow(rCBF) were measured based on moment analysis and the gamma variate method. These measurements, however, are not suitable for the detection of cerebral ischemia during the hyperacute stage. Therefore, we additionally studied the changes in a concentration curve (time-delta R* curve) of Gd-DTPA, injected into the median vein of the forearm. From the curve the SUM (delta R*) time to peak and the delta R* peak, which may be calculated quickly, were determined and were compared to rCBV, MTT, and rCBF, respectively. The rCBV and the rCBF in the ischemic regions were less than those in the contralateral healthy regions (p < 0.05), and the MTT in the ischemic regions was longer than that in the contralateral healthy regions (p < 0.05). Additionally, SUM (delta R*) and the delta R* peak in the ischemic regions were less, and the time to peak in the ischemic regions was longer than the value in the contralateral healthy regions (p < 0.05), correlating well to the rCBV, rCBF, and MTT measurements. Also, images of these parameters, depicting the ischemic lesion earlier than conventional T2 weighted images, can be easily made by using an MRI console. These results suggest that the SUM (delta R*), time to peak and the delta R* peak images calculated with dynamic contrast enhanced perfusion MRI may be one of the best techniques for the detection of cerebral ischemic lesions during the hyperacute stage.

  13. Optimization of flow-sensitive alternating inversion recovery (FAIR) for perfusion functional MRI of rodent brain.

    PubMed

    Nasrallah, Fatima A; Lee, Eugene L Q; Chuang, Kai-Hsiang

    2012-11-01

    Arterial spin labeling (ASL) MRI provides a noninvasive method to image perfusion, and has been applied to map neural activation in the brain. Although pulsed labeling methods have been widely used in humans, continuous ASL with a dedicated neck labeling coil is still the preferred method in rodent brain functional MRI (fMRI) to maximize the sensitivity and allow multislice acquisition. However, the additional hardware is not readily available and hence its application is limited. In this study, flow-sensitive alternating inversion recovery (FAIR) pulsed ASL was optimized for fMRI of rat brain. A practical challenge of FAIR is the suboptimal global inversion by the transmit coil of limited dimensions, which results in low effective labeling. By using a large volume transmit coil and proper positioning to optimize the body coverage, the perfusion signal was increased by 38.3% compared with positioning the brain at the isocenter. An additional 53.3% gain in signal was achieved using optimized repetition and inversion times compared with a long TR. Under electrical stimulation to the forepaws, a perfusion activation signal change of 63.7 ± 6.3% can be reliably detected in the primary somatosensory cortices using single slice or multislice echo planar imaging at 9.4 T. This demonstrates the potential of using pulsed ASL for multislice perfusion fMRI in functional and pharmacological applications in rat brain.

  14. 3D pulmonary perfusion MRI and MR angiography of pulmonary embolism in pigs after a single injection of a blood pool MR contrast agent.

    PubMed

    Fink, Christian; Ley, Sebastian; Puderbach, Michael; Plathow, Christian; Bock, Michael; Kauczor, Hans-Ulrich

    2004-07-01

    The purpose of this study was to assess the feasibility of contrast-enhanced 3D perfusion MRI and MR angiography (MRA) of pulmonary embolism (PE) in pigs using a single injection of the blood pool contrast Gadomer. PE was induced in five domestic pigs by injection of autologous blood thrombi. Contrast-enhanced first-pass 3D perfusion MRI (TE/TR/FA: 1.0 ms/2.2 ms/40 degrees; voxel size: 1.3 x 2.5 x 4.0 mm3; TA: 1.8 s per data set) and high-resolution 3D MRA (TE/TR/FA: 1.4 ms/3.4 ms/40 degrees; voxel size: 0.8 x 1.0 x 1.6 mm3) was performed during and after a single injection of 0.1 mmol/kg body weight of Gadomer. Image data were compared to pre-embolism Gd-DTPA-enhanced MRI and post-embolism thin-section multislice CT (n = 2). SNR measurements were performed in the pulmonary arteries and lung. One animal died after induction of PE. In all other animals, perfusion MRI and MRA could be acquired after a single injection of Gadomer. At perfusion MRI, PE could be detected by typical wedge-shaped perfusion defects. While the visualization of central PE at MRA correlated well with the CT, peripheral PE were only visualized by CT. Gadomer achieved a higher peak SNR of the lungs compared to Gd-DTPA (21 +/- 8 vs. 13 +/- 3). Contrast-enhanced 3D perfusion MRI and MRA of PE can be combined using a single injection of the blood pool contrast agent Gadomer.

  15. Dynamic contrast-enhanced susceptibility-weighted perfusion MRI (DSC-MRI) in a glioma model of the rat brain using a conventional receive-only surface coil with a inner diameter of 47 mm at a clinical 1.5 T scanner.

    PubMed

    Ulmer, Stephan; Reeh, Matthias; Krause, Joerg; Herdegen, Thomas; Heldt-Feindt, Janka; Jansen, Olav; Rohr, Axel

    2008-07-30

    Magnetic resonance (MR) imaging in animal models is usually performed in expensive dedicated small bore animal scanners of limited availability. In the present study a standard clinical 1.5 T MR scanner was used for morphometric and dynamic contrast-enhanced susceptibility-weighted MR imaging (DSC-MRI) of a glioma model of the rat brain. Ten male Wistar rats were examined with coronal T2-weighted, and T1-weighted images (matrix 128 x 128, FOV 64 mm) after implantation of an intracerebral tumor xenografts (C6) using a conventional surface coil. For DSC-MRI a T2*-weighted sequence (TR/TE=30/14 ms, matrix 64 x 64, FOV 90 mm; slice thickness of 1.5mm) was performed. Regions of interest were defined within the tumor and the non-affected contralateral hemisphere and the mean transit time (MTT) was determined. Tumor dimensions in MR predicted well its real size as proven by histology. The MTT of contrast agent passing through the brain was significantly decelerated in the tumor compared to the unaffected hemisphere (p<0.001, paired t-test), which is most likely due to the leakage of contrast agent through the disrupted blood brain barrier. This setup offers advanced MR imaging of small animals without the need for dedicated animal scanners or dedicated custom-made coils.

  16. The value of resting-state functional MRI in subacute ischemic stroke: comparison with dynamic susceptibility contrast-enhanced perfusion MRI.

    PubMed

    Ni, Ling; Li, Jingwei; Li, Weiping; Zhou, Fei; Wang, Fangfang; Schwarz, Christopher G; Liu, Renyuan; Zhao, Hui; Wu, Wenbo; Zhang, Xin; Li, Ming; Yu, Haiping; Zhu, Bin; Villringer, Arno; Zang, Yufeng; Zhang, Bing; Lv, Yating; Xu, Yun

    2017-01-31

    To evaluate the potential clinical value of the time-shift analysis (TSA) approach for resting-state fMRI (rs-fMRI) blood oxygenation level-dependent (BOLD) data in detecting hypoperfusion of subacute stroke patients through comparison with dynamic susceptibility contrast perfusion weighted imaging (DSC-PWI). Forty patients with subacute stroke (3-14 days after neurological symptom onset) underwent MRI examination. Cohort A: 31 patients had MRA, DSC-PWI and BOLD data. Cohort B: 9 patients had BOLD and MRA data. The time delay between the BOLD time course in each voxel and the mean signal of global and contralateral hemisphere was calculated using TSA. Time to peak (TTP) was employed to detect hypoperfusion. Among cohort A, 14 patients who had intracranial large-vessel occlusion/stenosis with sparse collaterals showed hypoperfusion by both of the two approaches, one with abundant collaterals showed neither TTP nor TSA time delay. The remaining 16 patients without obvious MRA lesions showed neither TTP nor TSA time delay. Among cohort B, eight patients showed time delay areas. The TSA approach was a promising alternative to DSC-PWI for detecting hypoperfusion in subacute stroke patients who had obvious MRA lesions with sparse collaterals, those with abundant collaterals would keep intact local perfusion.

  17. The value of resting-state functional MRI in subacute ischemic stroke: comparison with dynamic susceptibility contrast-enhanced perfusion MRI

    PubMed Central

    Ni, Ling; Li, Jingwei; Li, Weiping; Zhou, Fei; Wang, Fangfang; Schwarz, Christopher G.; Liu, Renyuan; Zhao, Hui; Wu, Wenbo; Zhang, Xin; Li, Ming; Yu, Haiping; Zhu, Bin; Villringer, Arno; Zang, Yufeng; Zhang, Bing; Lv, Yating; Xu, Yun

    2017-01-01

    To evaluate the potential clinical value of the time-shift analysis (TSA) approach for resting-state fMRI (rs-fMRI) blood oxygenation level-dependent (BOLD) data in detecting hypoperfusion of subacute stroke patients through comparison with dynamic susceptibility contrast perfusion weighted imaging (DSC-PWI). Forty patients with subacute stroke (3–14 days after neurological symptom onset) underwent MRI examination. Cohort A: 31 patients had MRA, DSC-PWI and BOLD data. Cohort B: 9 patients had BOLD and MRA data. The time delay between the BOLD time course in each voxel and the mean signal of global and contralateral hemisphere was calculated using TSA. Time to peak (TTP) was employed to detect hypoperfusion. Among cohort A, 14 patients who had intracranial large-vessel occlusion/stenosis with sparse collaterals showed hypoperfusion by both of the two approaches, one with abundant collaterals showed neither TTP nor TSA time delay. The remaining 16 patients without obvious MRA lesions showed neither TTP nor TSA time delay. Among cohort B, eight patients showed time delay areas. The TSA approach was a promising alternative to DSC-PWI for detecting hypoperfusion in subacute stroke patients who had obvious MRA lesions with sparse collaterals, those with abundant collaterals would keep intact local perfusion. PMID:28139701

  18. Interrelations of muscle functional MRI, diffusion-weighted MRI and (31) P-MRS in exercised lower back muscles.

    PubMed

    Hiepe, Patrick; Gussew, Alexander; Rzanny, Reinhard; Anders, Christoph; Walther, Mario; Scholle, Hans-Christoph; Reichenbach, Jürgen R

    2014-08-01

    Exercise-induced changes of transverse proton relaxation time (T2 ), tissue perfusion and metabolic turnover were investigated in the lower back muscles of volunteers by applying muscle functional MRI (mfMRI) and diffusion-weighted imaging (DWI) before and after as well as dynamic (31) P-MRS during the exercise. Inner (M. multifidus, MF) and outer lower back muscles (M. erector spinae, ES) were examined in 14 healthy young men performing a sustained isometric trunk-extension. Significant phosphocreatine (PCr) depletions ranging from 30% (ES) to 34% (MF) and Pi accumulations between 95% (left ES) and 120%-140% (MF muscles and right ES) were observed during the exercise, which were accompanied by significantly decreased pH values in all muscles (∆pH ≈ -0.05). Baseline T2 values were similar across all investigated muscles (approximately 27 ms at 3 T), but revealed right-left asymmetric increases (T2 ,inc ) after the exercise (right ES/MF: T2 ,inc  = 11.8/9.7%; left ES/MF: T2 ,inc  = 4.6/8.9%). Analyzed muscles also showed load-induced increases in molecular diffusion D (p = .007) and perfusion fraction f (p = .002). The latter parameter was significantly higher in the MF than in the ES muscles both at rest and post exercise. Changes in PCr (p = .03), diffusion (p < .01) and perfusion (p = .03) were strongly associated with T2,inc , and linear mixed model analysis revealed that changes in PCr and perfusion both affect T2,inc (p < .001). These findings support previous assumptions that T2 changes are not only an intra-cellular phenomenon resulting from metabolic stress but are also affected by increased perfusion in loaded muscles.

  19. Brain/language relationships identified with diffusion and perfusion MRI: Clinical applications in neurology and neurosurgery.

    PubMed

    Hillis, Argye E

    2005-12-01

    Diffusion and perfusion MRI have contributed to stroke management by identifying patients with tissue "at risk" for further damage in acute stroke. However, the potential usefulness of these imaging modalities, along with diffusion tensor imaging, can be expanded by using these imaging techniques with concurrent assessment of language and other cognitive skills to identify the specific cognitive deficits that are associated with diffusion and perfusion abnormalities in particular brain regions. This paper illustrates how this combined behavioral and imaging methodology can yield information that is useful for predicting specific positive effects of intervention to restore blood flow in hypoperfused regions of brain identified with perfusion MRI, and for predicting negative effects of resection of particular brain regions or fiber bundles. Such data allow decisions about neurological and neurosurgical interventions to be based on specific risks and benefits in terms of functional consequences.

  20. Spiral Perfusion Imaging With Consecutive Echoes (SPICE™) for the Simultaneous Mapping of DSC- and DCE-MRI Parameters in Brain Tumor Patients: Theory and Initial Feasibility.

    PubMed

    Paulson, Eric S; Prah, Douglas E; Schmainda, Kathleen M

    2016-12-01

    Dynamic contrast-enhanced (DCE) and dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) are the perfusion imaging techniques most frequently used to probe the angiogenic character of brain neoplasms. With these methods, T1- and T2/T2*-weighted imaging sequences are used to image the distribution of gadolinium (Gd)-based contrast agents. However, it is well known that Gd exhibits combined T1, T2, and T2* shortening effects in tissue, and therefore, the results of both DCE- and DSC-MRI can be confounded by these opposing effects. In particular, residual susceptibility effects compete with T1 shortening, which can confound DCE-MRI parameters, whereas dipolar T1 and T2 leakage and residual susceptibility effects can confound DSC-MRI parameters. We introduce here a novel perfusion imaging acquisition and postprocessing method termed Spiral Perfusion Imaging with Consecutive Echoes (SPICE) that can be used to simultaneously acquire DCE- and DSC-MRI data, which requires only a single dose of the Gd contrast agent, does not require the collection of a precontrast T1 map for DCE-MRI processing, and eliminates the confounding contrast agent effects due to contrast extravasation. A detailed mathematical description of SPICE is provided here along with a demonstration of its utility in patients with high-grade glioma.

  1. Spiral Perfusion Imaging With Consecutive Echoes (SPICE™) for the Simultaneous Mapping of DSC- and DCE-MRI Parameters in Brain Tumor Patients: Theory and Initial Feasibility

    PubMed Central

    Paulson, Eric S.; Prah, Douglas E.; Schmainda, Kathleen M.

    2017-01-01

    Dynamic contrast-enhanced (DCE) and dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) are the perfusion imaging techniques most frequently used to probe the angiogenic character of brain neoplasms. With these methods, T1- and T2/T2*-weighted imaging sequences are used to image the distribution of gadolinium (Gd)-based contrast agents. However, it is well known that Gd exhibits combined T1, T2, and T2* shortening effects in tissue, and therefore, the results of both DCE- and DSC-MRI can be confounded by these opposing effects. In particular, residual susceptibility effects compete with T1 shortening, which can confound DCE-MRI parameters, whereas dipolar T1 and T2 leakage and residual susceptibility effects can confound DSC-MRI parameters. We introduce here a novel perfusion imaging acquisition and postprocessing method termed Spiral Perfusion Imaging with Consecutive Echoes (SPICE) that can be used to simultaneously acquire DCE- and DSC-MRI data, which requires only a single dose of the Gd contrast agent, does not require the collection of a precontrast T1 map for DCE-MRI processing, and eliminates the confounding contrast agent effects due to contrast extravasation. A detailed mathematical description of SPICE is provided here along with a demonstration of its utility in patients with high-grade glioma. PMID:28090589

  2. Functional Cardiac Magnetic Resonance Imaging (MRI) in the Assessment of Myocardial Viability and Perfusion

    PubMed Central

    2003-01-01

    Executive Summary Objective The objective of this health technology policy assessment was to determine the effectiveness safety and cost-effectiveness of using functional cardiac magnetic resonance imaging (MRI) for the assessment of myocardial viability and perfusion in patients with coronary artery disease and left ventricular dysfunction. Results Functional MRI has become increasingly investigated as a noninvasive method for assessing myocardial viability and perfusion. Most patients in the published literature have mild to moderate impaired LV function. It is possible that the severity of LV dysfunction may be an important factor that can alter the diagnostic accuracy of imaging techniques. There is some evidence of comparable or better performance of functional cardiac MRI for the assessment of myocardial viability and perfusion compared with other imaging techniques. However limitations to most of the studies included: Functional cardiac MRI studies that assess myocardial viability and perfusion have had small sample sizes. Some studies assessed myocardial viability/perfusion in patients who had already undergone revascularization, or excluded patients with a prior MI (Schwitter et al., 2001). Lack of explicit detail of patient recruitment. Patients with LVEF >35%. Interstudy variability in post MI imaging time(including acute or chronic MI), when patients with a prior MI were included. Poor interobserver agreement (kappa statistic) in the interpretation of the results. Traditionally, 0.80 is considered “good”. Cardiac MRI measurement of myocardial perfusion to as an adjunct tool to help diagnose CAD (prior to a definitive coronary angiography) has also been examined in some studies, with methodological limitations, yielding comparable results. Many studies examining myocardial viability and perfusion report on the accuracy of imaging methods with limited data on long-term patient outcome and management. Kim et al. (2000) revealed that the transmural

  3. Cerebral perfusion alterations in epileptic patients during peri-ictal and post-ictal phase: PASL vs DSC-MRI.

    PubMed

    Pizzini, Francesca B; Farace, Paolo; Manganotti, Paolo; Zoccatelli, Giada; Bongiovanni, Luigi G; Golay, Xavier; Beltramello, Alberto; Osculati, Antonio; Bertini, Giuseppe; Fabene, Paolo F

    2013-07-01

    Non-invasive pulsed arterial spin labeling (PASL) MRI is a method to study brain perfusion that does not require the administration of a contrast agent, which makes it a valuable diagnostic tool as it reduces cost and side effects. The purpose of the present study was to establish the viability of PASL as an alternative to dynamic susceptibility contrast (DSC-MRI) and other perfusion imaging methods in characterizing changes in perfusion patterns caused by seizures in epileptic patients. We evaluated 19 patients with PASL. Of these, the 9 affected by high-frequency seizures were observed during the peri-ictal period (within 5hours since the last seizure), while the 10 patients affected by low-frequency seizures were observed in the post-ictal period. For comparison, 17/19 patients were also evaluated with DSC-MRI and CBF/CBV. PASL imaging showed focal vascular changes, which allowed the classification of patients in three categories: 8 patients characterized by increased perfusion, 4 patients with normal perfusion and 7 patients with decreased perfusion. PASL perfusion imaging findings were comparable to those obtained by DSC-MRI. Since PASL is a) sensitive to vascular alterations induced by epileptic seizures, b) comparable to DSC-MRI for detecting perfusion asymmetries, c) potentially capable of detecting time-related perfusion changes, it can be recommended for repeated evaluations, to identify the epileptic focus, and in follow-up and/or therapy-response assessment.

  4. Non-ECG-Gated Myocardial Perfusion MRI Using Continuous Magnetization-Driven Radial Sampling

    PubMed Central

    Sharif, Behzad; Dharmakumar, Rohan; Arsanjani, Reza; Thomson, Louise; Merz, C. Noel Bairey; Berman, Daniel S.; Li, Debiao

    2014-01-01

    Purpose Establishing a high-resolution non-ECG-gated first-pass perfusion (FPP) cardiac MRI technique may improve accessibility and diagnostic capability of FPP imaging. We propose a non-ECG-gated FPP imaging technique using continuous magnetization-driven golden-angle radial acquisition. The main purpose of this preliminary study is to evaluate whether, in the simple case of single-slice 2D imaging, adequate myocardial contrast can be obtained for accurate visualization of hypoperfused territories in the setting of myocardial ischemia. Methods A T1-weighted pulse sequence with continuous golden-angle radial sampling was developed for non-ECG-gated FPP imaging. A sliding-window scheme with no temporal acceleration was used to reconstruct 8 frames/second. Canines were imaged at 3T with and without coronary stenosis using the proposed scheme and a conventional magnetization-prepared ECG-gated FPP method. Results Our studies showed that the proposed non-ECG-gated method is capable of generating high-resolution (1.7×1.7×6 mm3) artifact-free FPP images of a single slice at high heart rates (92±21 beats/minute), while matching the performance of conventional FPP imaging in terms of hypoperfused-to-normal myocardial contrast-to-noise ratio (proposed: 5.18±0.70, conventional: 4.88±0.43). Furthermore, the detected perfusion defect areas were consistent with the conventional FPP images. Conclusion Non-ECG-gated FPP imaging using optimized continuous golden-angle radial acquisition achieves desirable image quality (i.e., adequate myocardial contrast, high spatial resolution, and minimal artifacts) in the setting of ischemia. PMID:24443160

  5. A methodology for generating normal and pathological brain perfusion SPECT images for evaluation of MRI/SPECT fusion methods: application in epilepsy

    NASA Astrophysics Data System (ADS)

    Grova, C.; Jannin, P.; Biraben, A.; Buvat, I.; Benali, H.; Bernard, A. M.; Scarabin, J. M.; Gibaud, B.

    2003-12-01

    Quantitative evaluation of brain MRI/SPECT fusion methods for normal and in particular pathological datasets is difficult, due to the frequent lack of relevant ground truth. We propose a methodology to generate MRI and SPECT datasets dedicated to the evaluation of MRI/SPECT fusion methods and illustrate the method when dealing with ictal SPECT. The method consists in generating normal or pathological SPECT data perfectly aligned with a high-resolution 3D T1-weighted MRI using realistic Monte Carlo simulations that closely reproduce the response of a SPECT imaging system. Anatomical input data for the SPECT simulations are obtained from this 3D T1-weighted MRI, while functional input data result from an inter-individual analysis of anatomically standardized SPECT data. The method makes it possible to control the 'brain perfusion' function by proposing a theoretical model of brain perfusion from measurements performed on real SPECT images. Our method provides an absolute gold standard for assessing MRI/SPECT registration method accuracy since, by construction, the SPECT data are perfectly registered with the MRI data. The proposed methodology has been applied to create a theoretical model of normal brain perfusion and ictal brain perfusion characteristic of mesial temporal lobe epilepsy. To approach realistic and unbiased perfusion models, real SPECT data were corrected for uniform attenuation, scatter and partial volume effect. An anatomic standardization was used to account for anatomic variability between subjects. Realistic simulations of normal and ictal SPECT deduced from these perfusion models are presented. The comparison of real and simulated SPECT images showed relative differences in regional activity concentration of less than 20% in most anatomical structures, for both normal and ictal data, suggesting realistic models of perfusion distributions for evaluation purposes. Inter-hemispheric asymmetry coefficients measured on simulated data were found within

  6. A methodology for generating normal and pathological brain perfusion SPECT images for evaluation of MRI/SPECT fusion methods: application in epilepsy.

    PubMed

    Grova, C; Jannin, P; Biraben, A; Buvat, I; Benali, H; Bernard, A M; Scarabin, J M; Gibaud, B

    2003-12-21

    Quantitative evaluation of brain MRI/SPECT fusion methods for normal and in particular pathological datasets is difficult, due to the frequent lack of relevant ground truth. We propose a methodology to generate MRI and SPECT datasets dedicated to the evaluation of MRI/SPECT fusion methods and illustrate the method when dealing with ictal SPECT. The method consists in generating normal or pathological SPECT data perfectly aligned with a high-resolution 3D T1-weighted MRI using realistic Monte Carlo simulations that closely reproduce the response of a SPECT imaging system. Anatomical input data for the SPECT simulations are obtained from this 3D T1-weighted MRI, while functional input data result from an inter-individual analysis of anatomically standardized SPECT data. The method makes it possible to control the 'brain perfusion' function by proposing a theoretical model of brain perfusion from measurements performed on real SPECT images. Our method provides an absolute gold standard for assessing MRI/SPECT registration method accuracy since, by construction, the SPECT data are perfectly registered with the MRI data. The proposed methodology has been applied to create a theoretical model of normal brain perfusion and ictal brain perfusion characteristic of mesial temporal lobe epilepsy. To approach realistic and unbiased perfusion models, real SPECT data were corrected for uniform attenuation, scatter and partial volume effect. An anatomic standardization was used to account for anatomic variability between subjects. Realistic simulations of normal and ictal SPECT deduced from these perfusion models are presented. The comparison of real and simulated SPECT images showed relative differences in regional activity concentration of less than 20% in most anatomical structures, for both normal and ictal data, suggesting realistic models of perfusion distributions for evaluation purposes. Inter-hemispheric asymmetry coefficients measured on simulated data were found within

  7. Resting State Brain Function Analysis Using Concurrent BOLD in ASL Perfusion fMRI

    PubMed Central

    Zhu, Senhua; Fang, Zhuo; Hu, Siyuan; Wang, Ze; Rao, Hengyi

    2013-01-01

    The past decade has seen astounding discoveries about resting-state brain activity patterns in normal brain as well as their alterations in brain diseases. While the vast majority of resting-state studies are based on the blood-oxygen-level-dependent (BOLD) functional MRI (fMRI), arterial spin labeling (ASL) perfusion fMRI can simultaneously capture BOLD and cerebral blood flow (CBF) signals, providing a unique opportunity for assessing resting brain functions with concurrent BOLD (ccBOLD) and CBF signals. Before taking that benefit, it is necessary to validate the utility of ccBOLD signal for resting-state analysis using conventional BOLD (cvBOLD) signal acquired without ASL modulations. To address this technical issue, resting cvBOLD and ASL perfusion MRI were acquired from a large cohort (n = 89) of healthy subjects. Four widely used resting-state brain function analyses were conducted and compared between the two types of BOLD signal, including the posterior cingulate cortex (PCC) seed-based functional connectivity (FC) analysis, independent component analysis (ICA), analysis of amplitude of low frequency fluctuation (ALFF), and analysis of regional homogeneity (ReHo). Consistent default mode network (DMN) as well as other resting-state networks (RSNs) were observed from cvBOLD and ccBOLD using PCC-FC analysis and ICA. ALFF from both modalities were the same for most of brain regions but were different in peripheral regions suffering from the susceptibility gradients induced signal drop. ReHo showed difference in many brain regions, likely reflecting the SNR and resolution differences between the two BOLD modalities. The DMN and auditory networks showed highest CBF values among all RSNs. These results demonstrated the feasibility of ASL perfusion MRI for assessing resting brain functions using its concurrent BOLD in addition to CBF signal, which provides a potentially useful way to maximize the utility of ASL perfusion MRI. PMID:23750275

  8. Dynamic Contrast-Enhanced MRI Perfusion Parameters as Imaging Biomarkers of Angiogenesis

    PubMed Central

    2016-01-01

    Hypoxia in the tumor microenvironment is the leading factor in angiogenesis. Angiogenesis can be identified by dynamic contrast-enhanced breast MRI (DCE MRI). Here we investigate the relationship between perfusion parameters on DCE MRI and angiogenic and prognostic factors in patients with invasive ductal carcinoma (IDC). Perfusion parameters (Ktrans, kep and ve) of 81 IDC were obtained using histogram analysis. Twenty-fifth, 50th and 75th percentile values were calculated and were analyzed for association with microvessel density (MVD), vascular endothelial growth factor (VEGF) and conventional prognostic factors. Correlation between MVD and ve50 was positive (r = 0.33). Ktrans50 was higher in tumors larger than 2 cm than in tumors smaller than 2 cm. In multivariate analysis, Ktrans50 was affected by tumor size and MVD with 12.8% explanation. There was significant association between Ktrans50 and tumor size and MVD. Therefore we conclude that DCE MRI perfusion parameters are potential imaging biomarkers for prediction of tumor angiogenesis and aggressiveness. PMID:28036342

  9. The correlation of contrast-enhanced ultrasound and MRI perfusion quantitative analysis in rabbit VX2 liver cancer.

    PubMed

    Xiang, Zhiming; Liang, Qianwen; Liang, Changhong; Zhong, Guimian

    2014-12-01

    Our objective is to explore the value of liver cancer contrast-enhanced ultrasound (CEUS) and MRI perfusion quantitative analysis in liver cancer and the correlation between these two analysis methods. Rabbit VX2 liver cancer model was established in this study. CEUS was applied. Sono Vue was applied in rabbits by ear vein to dynamically observe and record the blood perfusion and changes in the process of VX2 liver cancer and surrounding tissue. MRI perfusion quantitative analysis was used to analyze the mean enhancement time and change law of maximal slope increasing, which were further compared with the pathological examination results. Quantitative indicators of liver cancer CEUS and MRI perfusion quantitative analysis were compared, and the correlation between them was analyzed by correlation analysis. Rabbit VX2 liver cancer model was successfully established. CEUS showed that time-intensity curve of rabbit VX2 liver cancer showed "fast in, fast out" model while MRI perfusion quantitative analysis showed that quantitative parameter MTE of tumor tissue increased and MSI decreased: the difference was statistically significant (P < 0.01). The diagnostic results of CEUS and MRI perfusion quantitative analysis were not significantly different (P > 0.05). However, the quantitative parameter of them were significantly positively correlated (P < 0.05). CEUS and MRI perfusion quantitative analysis can both dynamically monitor the liver cancer lesion and surrounding liver parenchyma, and the quantitative parameters of them are correlated. The combined application of both is of importance in early diagnosis of liver cancer.

  10. Quantitative Perfusion Analysis of First-Pass Contrast Enhancement Kinetics: Application to MRI of Myocardial Perfusion in Coronary Artery Disease

    PubMed Central

    Shah, Binita; Storey, Pippa; Iqbal, Sohah; Slater, James; Axel, Leon

    2016-01-01

    Purpose Perfusion analysis from first-pass contrast enhancement kinetics requires modeling tissue contrast exchange. This study presents a new approach for numerical implementation of the tissue homogeneity model, incorporating flexible distance steps along the capillary (NTHf). Methods The proposed NTHf model considers contrast exchange in fluid packets flowing along the capillary, incorporating flexible distance steps, thus allowing more efficient and stable calculations of the transit of tracer through the tissue. We prospectively studied 8 patients (62 ± 13 years old) with suspected CAD, who underwent first-pass perfusion CMR imaging at rest and stress prior to angiography. Myocardial blood flow (MBF) and myocardial perfusion reserve index (MPRI) were estimated using both the NTHf and the conventional adiabatic approximation of the TH models. Coronary artery lesions detected at angiography were clinically assigned to one of three categories of stenosis severity (‘insignificant’, ‘mild to moderate’ and ‘severe’) and related to corresponding myocardial territories. Results The mean MBF (ml/g/min) at rest/stress and MPRI were 0.80 ± 0.33/1.25 ± 0.45 and 1.68 ± 0.54 in the insignificant regions, 0.74 ± 0.21/1.09 ± 0.28 and 1.54 ± 0.46 in the mild to moderate regions, and 0.79 ± 0.28/0.63 ± 0.34 and 0.85 ± 0.48 in the severe regions, respectively. The correlation coefficients of MBFs at rest/stress and MPRI between the NTHf and AATH models were r = 0.97/0.93 and r = 0.91, respectively. Conclusions The proposed NTHf model allows efficient quantitative analysis of the transit of tracer through tissue, particularly at higher flow. Results of initial application to MRI of myocardial perfusion in CAD are encouraging. PMID:27583385

  11. Non-contrast-enhanced perfusion and ventilation assessment of the human lung by means of fourier decomposition in proton MRI.

    PubMed

    Bauman, Grzegorz; Puderbach, Michael; Deimling, Michael; Jellus, Vladimir; Chefd'hotel, Christophe; Dinkel, Julien; Hintze, Christian; Kauczor, Hans-Ulrich; Schad, Lothar R

    2009-09-01

    Assessment of regional lung perfusion and ventilation has significant clinical value for the diagnosis and follow-up of pulmonary diseases. In this work a new method of non-contrast-enhanced functional lung MRI (not dependent on intravenous or inhalative contrast agents) is proposed. A two-dimensional (2D) true fast imaging with steady precession (TrueFISP) pulse sequence (TR/TE = 1.9 ms/0.8 ms, acquisition time [TA] = 112 ms/image) was implemented on a 1.5T whole-body MR scanner. The imaging protocol comprised sets of 198 lung images acquired with an imaging rate of 3.33 images/s in coronal and sagittal view. No electrocardiogram (ECG) or respiratory triggering was used. A nonrigid image registration algorithm was applied to compensate for respiratory motion. Rapid data acquisition allowed observing intensity changes in corresponding lung areas with respect to the cardiac and respiratory frequencies. After a Fourier analysis along the time domain, two spectral lines corresponding to both frequencies were used to calculate the perfusion- and ventilation-weighted images. The described method was applied in preliminary studies on volunteers and patients showing clinical relevance to obtain non-contrast-enhanced perfusion and ventilation data.

  12. The diagnostic performance of perfusion MRI for differentiating glioma recurrence from pseudoprogression

    PubMed Central

    Wan, Bing; Wang, Siqi; Tu, Mengqi; Wu, Bo; Han, Ping; Xu, Haibo

    2017-01-01

    Abstract Background: The purpose of this meta-analysis was to evaluate the diagnostic accuracy of perfusion magnetic resonance imaging (MRI) as a method for differentiating glioma recurrence from pseudoprogression. Methods: The PubMed, Embase, Cochrane Library, and Chinese Biomedical databases were searched comprehensively for relevant studies up to August 3, 2016 according to specific inclusion and exclusion criteria. The quality of the included studies was assessed according to the quality assessment of diagnostic accuracy studies (QUADAS-2). After performing heterogeneity and threshold effect tests, pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were calculated. Publication bias was evaluated visually by a funnel plot and quantitatively using Deek funnel plot asymmetry test. The area under the summary receiver operating characteristic curve was calculated to demonstrate the diagnostic performance of perfusion MRI. Results: Eleven studies covering 416 patients and 418 lesions were included in this meta-analysis. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 0.88 (95% confidence interval [CI] 0.84–0.92), 0.77 (95% CI 0.69–0.84), 3.93 (95% CI 2.83–5.46), 0.16 (95% CI 0.11–0.22), and 27.17 (95% CI 14.96–49.35), respectively. The area under the summary receiver operating characteristic curve was 0.8899. There was no notable publication bias. Sensitivity analysis showed that the meta-analysis results were stable and credible. Conclusion: While perfusion MRI is not the ideal diagnostic method for differentiating glioma recurrence from pseudoprogression, it could improve diagnostic accuracy. Therefore, further research on combining perfusion MRI with other imaging modalities is warranted. PMID:28296759

  13. Perfusion deconvolution in DSC-MRI with dispersion-compliant bases.

    PubMed

    Pizzolato, Marco; Boutelier, Timothé; Deriche, Rachid

    2017-02-01

    Perfusion imaging of the brain via Dynamic Susceptibility Contrast MRI (DSC-MRI) allows tissue perfusion characterization by recovering the tissue impulse response function and scalar parameters such as the cerebral blood flow (CBF), blood volume (CBV), and mean transit time (MTT). However, the presence of bolus dispersion causes the data to reflect macrovascular properties, in addition to tissue perfusion. In this case, when performing deconvolution of the measured arterial and tissue concentration time-curves it is only possible to recover the effective, i.e. dispersed, response function and parameters. We introduce Dispersion-Compliant Bases (DCB) to represent the response function in the presence and absence of dispersion. We perform in silico and in vivo experiments, and show that DCB deconvolution outperforms oSVD and the state-of-the-art CPI+VTF techniques in the estimation of effective perfusion parameters, regardless of the presence and amount of dispersion. We also show that DCB deconvolution can be used as a pre-processing step to improve the estimation of dispersion-free parameters computed with CPI+VTF, which employs a model of the vascular transport function to characterize dispersion. Indeed, in silico results show a reduction of relative errors up to 50% for dispersion-free CBF and MTT. Moreover, the DCB method recovers effective response functions that comply with healthy and pathological scenarios, and offers the advantage of making no assumptions about the presence, amount, and nature of dispersion.

  14. Perfusion and diffusion MRI of glioblastoma progression in a four-year prospective temozolomide clinical trial

    SciTech Connect

    Leimgruber, Antoine; Ostermann, Sandrine; Yeon, Eun Jo; Buff, Evelyn; Maeder, Philippe P.; Stupp, Roger; Meuli, Reto A. . E-mail: Reto.Meuli@chuv.ch

    2006-03-01

    Purpose: This study was performed to determine the impact of perfusion and diffusion magnetic resonance imaging (MRI) sequences on patients during treatment of newly diagnosed glioblastoma. Special emphasis has been given to these imaging technologies as tools to potentially anticipate disease progression, as progression-free survival is frequently used as a surrogate endpoint. Methods and Materials: Forty-one patients from a phase II temolozomide clinical trial were included. During follow-up, images were integrated 21 to 28 days after radiochemotherapy and every 2 months thereafter. Assessment of scans included measurement of size of lesion on T1 contrast-enhanced, T2, diffusion, and perfusion images, as well as mass effect. Classical criteria on tumor size variation and clinical parameters were used to set disease progression date. Results: A total of 311 MRI examinations were reviewed. At disease progression (32 patients), a multivariate Cox regression determined 2 significant survival parameters: T1 largest diameter (p < 0.02) and T2 size variation (p < 0.05), whereas perfusion and diffusion were not significant. Conclusion: Perfusion and diffusion techniques cannot be used to anticipate tumor progression. Decision making at disease progression is critical, and classical T1 and T2 imaging remain the gold standard. Specifically, a T1 contrast enhancement over 3 cm in largest diameter together with an increased T2 hypersignal is a marker of inferior prognosis.

  15. 3.0T MR investigation of CLIPPERS: role of susceptibility weighted and perfusion weighted imaging.

    PubMed

    Pesaresi, Ilaria; Sabato, Mario; Desideri, Ilaria; Puglioli, Michele; Moretti, Policarpo; Cosottini, Mirco

    2013-11-01

    For the first time we describe and interpret Susceptibility Weighted Imaging (SWI) and Perfusion Weighted Imaging (PWI) findings in a case of Chronic Lymphocytic Inflammation with Perivascular Pontine Enhancement Responsive to Steroids (CLIPPERS). The diagnosis of the disease was formulated on the basis of typical Magnetic Resonance (MR) findings and its responsiveness to steroids in a 40-year-old man with acute onset of dizziness, ataxia and diplopia. The patient underwent a 3 tesla (T) MR examination including SWI and PWI sequences. SWI revealed prominent veins and multiple hypointense lesions of different size widely distributed in brainstem and cerebellum, which could be expression of iron deposition or cellular infiltrates. PWI demonstrated global infratentorial hypoperfusion. SWI and PWI provide new information on CLIPPERS that might be helpful to understand the physiopathology of the disease. Further observations are needed to evaluate if these findings are peculiar for CLIPPERS and if they might have a role in a non-invasive diagnosis of the disease.

  16. Contrast-enhanced CT- and MRI-based perfusion assessment for pulmonary diseases: basics and clinical applications

    PubMed Central

    Ohno, Yoshiharu; Koyama, Hisanobu; Lee, Ho Yun; Miura, Sachiko; Yoshikawa, Takeshi; Sugimura, Kazuro

    2016-01-01

    Assessment of regional pulmonary perfusion as well as nodule and tumor perfusions in various pulmonary diseases are currently performed by means of nuclear medicine studies requiring radioactive macroaggregates, dual-energy computed tomography (CT), and dynamic first-pass contrast-enhanced perfusion CT techniques and unenhanced and dynamic first-pass contrast enhanced perfusion magnetic resonance imaging (MRI), as well as time-resolved three-dimensional or four-dimensional contrast-enhanced magnetic resonance angiography (MRA). Perfusion scintigraphy, single-photon emission tomography (SPECT) and SPECT fused with CT have been established as clinically available scintigraphic methods; however, they are limited by perfusion information with poor spatial resolution and other shortcomings. Although positron emission tomography with 15O water can measure absolute pulmonary perfusion, it requires a cyclotron for generation of a tracer with an extremely short half-life (2 min), and can only be performed for academic purposes. Therefore, clinicians are concentrating their efforts on the application of CT-based and MRI-based quantitative and qualitative perfusion assessment to various pulmonary diseases. This review article covers 1) the basics of dual-energy CT and dynamic first-pass contrast-enhanced perfusion CT techniques, 2) the basics of time-resolved contrast-enhanced MRA and dynamic first-pass contrast-enhanced perfusion MRI, and 3) clinical applications of contrast-enhanced CT- and MRI-based perfusion assessment for patients with pulmonary nodule, lung cancer, and pulmonary vascular diseases. We believe that these new techniques can be useful in routine clinical practice for not only thoracic oncology patients, but also patients with different pulmonary vascular diseases. PMID:27523813

  17. Repeatability of Cerebral Perfusion Using Dynamic Susceptibility Contrast MRI in Glioblastoma Patients12

    PubMed Central

    Jafari-Khouzani, Kourosh; Emblem, Kyrre E.; Kalpathy-Cramer, Jayashree; Bjørnerud, Atle; Vangel, Mark G.; Gerstner, Elizabeth R.; Schmainda, Kathleen M.; Paynabar, Kamran; Wu, Ona; Wen, Patrick Y.; Batchelor, Tracy; Rosen, Bruce; Stufflebeam, Steven M.

    2015-01-01

    OBJECTIVES This study evaluates the repeatability of brain perfusion using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) with a variety of post-processing methods. METHODS Thirty-two patients with newly diagnosed glioblastoma were recruited. On a 3-T MRI using a dual-echo, gradient-echo spin-echo DSC-MRI protocol, the patients were scanned twice 1 to 5 days apart. Perfusion maps including cerebral blood volume (CBV) and cerebral blood flow (CBF) were generated using two contrast agent leakage correction methods, along with testing normalization to reference tissue, and application of arterial input function (AIF). Repeatability of CBV and CBF within tumor regions and healthy tissues, identified by structural images, was assessed with intra-class correlation coefficients (ICCs) and repeatability coefficients (RCs). Coefficients of variation (CVs) were reported for selected methods. RESULTS CBV and CBF were highly repeatable within tumor with ICC values up to 0.97. However, both CBV and CBF showed lower ICCs for healthy cortical tissues (up to 0.83), healthy gray matter (up to 0.95), and healthy white matter (WM; up to 0.93). The values of CV ranged from 6% to 10% in tumor and 3% to 11% in healthy tissues. The values of RC relative to the mean value of measurement within healthy WM ranged from 22% to 42% in tumor and 7% to 43% in healthy tissues. These percentages show how much variation in perfusion parameter, relative to that in healthy WM, we expect to observe to consider it statistically significant. We also found that normalization improved repeatability, but AIF deconvolution did not. CONCLUSIONS DSC-MRI is highly repeatable in high-grade glioma patients. PMID:26055170

  18. Automated scoring of regional lung perfusion in children from contrast enhanced 3D MRI

    NASA Astrophysics Data System (ADS)

    Heimann, Tobias; Eichinger, Monika; Bauman, Grzegorz; Bischoff, Arved; Puderbach, Michael; Meinzer, Hans-Peter

    2012-03-01

    MRI perfusion images give information about regional lung function and can be used to detect pulmonary pathologies in cystic fibrosis (CF) children. However, manual assessment of the percentage of pathologic tissue in defined lung subvolumes features large inter- and intra-observer variation, making it difficult to determine disease progression consistently. We present an automated method to calculate a regional score for this purpose. First, lungs are located based on thresholding and morphological operations. Second, statistical shape models of left and right children's lungs are initialized at the determined locations and used to precisely segment morphological images. Segmentation results are transferred to perfusion maps and employed as masks to calculate perfusion statistics. An automated threshold to determine pathologic tissue is calculated and used to determine accurate regional scores. We evaluated the method on 10 MRI images and achieved an average surface distance of less than 1.5 mm compared to manual reference segmentations. Pathologic tissue was detected correctly in 9 cases. The approach seems suitable for detecting early signs of CF and monitoring response to therapy.

  19. Combination of Compressed Sensing and Parallel Imaging for Highly Accelerated First-Pass Cardiac Perfusion MRI

    PubMed Central

    Otazo, Ricardo; Kim, Daniel; Axel, Leon; Sodickson, Daniel K.

    2010-01-01

    First-pass cardiac perfusion MRI is a natural candidate for compressed sensing acceleration since its representation in the combined temporal Fourier and spatial domain is sparse and the required incoherence can be effectively accomplished by k-t random undersampling. However, the required number of samples in practice (three to five times the number of sparse coefficients) limits the acceleration for compressed sensing alone. Parallel imaging may also be used to accelerate cardiac perfusion MRI, with acceleration factors ultimately limited by noise amplification. In this work, compressed sensing and parallel imaging are combined by merging the k-t SPARSE technique with SENSE reconstruction to substantially increase the acceleration rate for perfusion imaging. We also present a new theoretical framework for understanding the combination of k-t SPARSE with SENSE based on distributed compressed sensing theory. This framework, which identifies parallel imaging as a distributed multisensor implementation of compressed sensing, enables an estimate of feasible acceleration for the combined approach. We demonstrate feasibility of 8-fold acceleration in vivo with whole-heart coverage and high spatial and temporal resolution using standard coil arrays. The method is relatively insensitive to respiratory motion artifacts and presents similar temporal fidelity and image quality when compared to GRAPPA with 2-fold acceleration. PMID:20535813

  20. Uncertainty in the analysis of tracer kinetics using dynamic contrast-enhanced T1-weighted MRI.

    PubMed

    Buckley, David L

    2002-03-01

    In recent years a number of physiological models have gained prominence in the analysis of dynamic contrast-enhanced T1-weighted MRI data. However, there remains little evidence to support their use in estimating the absolute values of tissue physiological parameters such as perfusion, capillary permeability, and blood volume. In an attempt to address this issue, data were simulated using a distributed pathway model of tracer kinetics, and three published models were fitted to the resultant concentration-time curves. Parameter estimates obtained from these fits were compared with the parameters used for the simulations. The results indicate that the use of commonly accepted models leads to systematic overestimation of the transfer constant, Ktrans, and potentially large underestimates of the blood plasma volume fraction, Vp. In summary, proposals for a practical approach to physiological modeling using MRI data are outlined.

  1. Study on the cerebrovascular reserve capacity by MR perfusion weighted imaging in SHR

    NASA Astrophysics Data System (ADS)

    Zhou, Quan; Dong, Yang; Chen, WenLi; Lin, Xueying; Xing, Da; Huang, Li

    2007-05-01

    Cerebrovascular disease is one of the leading causes of death, and approximately 50% of survivors have a residual neurologic deficit and greater than 25% require chronic care. Cerebrovascular reserve capacity (CVRC) describes how far cerebral perfusion can increase from a baseline value after stimulation. High blood pressure is the most important independent risk factor for stroke and other vascular diseases. The incidence of stroke in the hypertensive is six times higher than in the patient with normal blood pressure. CVRC in the hypertensive was even lower than in control patients. MR perfusion weighted imaging (MR PWI) with the well-established acetazolamide (ACZ) stimulation test has been used for assessing brain function. The aim of this work is to assess the cerebrovascular reserve capacity by MR PWI with "ACZ" tolerance test in spontaneous hypertensive rat (SHR) and to identify its value in evaluating the CVRC. Experimental animal including 3 groups: Wistar-Kyoto rats (WKY) (12-week-old) as control group, SHR (12-week-old and 20-week-old) as experimental group. MR PWI was performed respectively before and after acetazolamide administrated orally in 3 groups on a clinical 1.5 Tesla GE Signa MR fx/i whole-body MR system. The ROI was chosen in the bilateral frontal lobe to measure the value of rCBV, rCBF and MTT. The results showed that before ACZ-test, there was statistic differences between the WKY and SHR(12-week-old), and between SHR(12-week-old) and SHR(20-week-old) in the values of rCBV and rCBF (P>0.05), and after ACZ-test, there were statistic differences between WKY and SHR (20-week-old), and between SHR(12-week-old) and SHR(20-week-old) in the rCBV value (P<0.05). It is concluded that the method of MRI PWI combined with the "ACZ stress test" can provide more qualitative and half-quantitative information on the cerebral perfusion to evaluate the CVRC in SHR.

  2. Stepwise heterogeneity analysis of breast tumors in perfusion DCE-MRI datasets

    NASA Astrophysics Data System (ADS)

    Mohajer, Mojgan; Schmid, Volker J.; Engels, Nina A.; Noel, Peter B.; Rummeny, Ernst; Englmeier, Karl-Hans

    2012-03-01

    The signal curves in perfusion dynamic contrast enhanced MRI (DCE-MRI) of cancerous breast tissue reveal valuable information about tumor angiogenesis. Pathological studies have illustrated that breast tumors consist of different subregions, especially with more homogeneous properties during their growth. Differences should be identifiable in DCEMRI signal curves if the characteristics of these sub-regions are related to the perfusion and angiogenesis. We introduce a stepwise clustering method which in a first step uses a new similarity measure. The new similarity measure (PM) compares how parallel washout phases of two curves are. To distinguish the starting point of the washout phase, a linear regression method is partially fitted to the curves. In the next step, the minimum signal value of the washout phase is normalized to zero. Finally, PM is calculated according to maximal variation among the point wise differences during washout phases. In the second step of clustering the groups of signal curves with parallel washout are clustered using Euclidean distance. The introduced method is evaluated on 15 DCE-MRI breast datasets with different types of breast tumors. The use of our new heterogeneity analysis is feasible in single patient examination and improves breast MR diagnostics.

  3. Semi-quantitative assessment of pulmonary perfusion in children using dynamic contrast-enhanced MRI

    NASA Astrophysics Data System (ADS)

    Fetita, Catalin; Thong, William E.; Ou, Phalla

    2013-03-01

    This paper addresses the study of semi-quantitative assessment of pulmonary perfusion acquired from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in a study population mainly composed of children with pulmonary malformations. The automatic analysis approach proposed is based on the indicator-dilution theory introduced in 1954. First, a robust method is developed to segment the pulmonary artery and the lungs from anatomical MRI data, exploiting 2D and 3D mathematical morphology operators. Second, the time-dependent contrast signal of the lung regions is deconvolved by the arterial input function for the assessment of the local hemodynamic system parameters, ie. mean transit time, pulmonary blood volume and pulmonary blood flow. The discrete deconvolution method implements here a truncated singular value decomposition (tSVD) method. Parametric images for the entire lungs are generated as additional elements for diagnosis and quantitative follow-up. The preliminary results attest the feasibility of perfusion quantification in pulmonary DCE-MRI and open an interesting alternative to scintigraphy for this type of evaluation, to be considered at least as a preliminary decision in the diagnostic due to the large availability of the technique and to the non-invasive aspects.

  4. Free-breathing myocardial perfusion MRI using SW-CG-HYPR and motion correction.

    PubMed

    Ge, Lan; Kino, Aya; Griswold, Mark; Carr, James C; Li, Debiao

    2010-10-01

    First-pass perfusion MRI is a promising technique to detect ischemic heart disease. Sliding window (SW) conjugate-gradient (CG) highly constrained back-projection reconstruction (HYPR) (SW-CG-HYPR) has been proposed to increase spatial coverage, spatial resolution, and SNR. However, this method is sensitive to respiratory motion and thus requires breath-hold. This work presents a non-model-based motion correction method combined with SW-CG-HYPR to perform free-breathing myocardial MR imaging. Simulation studies were first performed to show the effectiveness of the proposed motion correction method and its independence from the pattern of the respiratory motion. After that, in vivo studies were performed in six healthy volunteers. From all of the volunteer studies, the image quality score of free breathing perfusion images with motion correction (3.11 ± 0.34) is improved compared with that of images without motion correction (2.27 ± 0.32), and is comparable with that of successful breath-hold images (3.12 ± 0.38). This result was further validated by a quantitative sharpness analysis. The left ventricle and myocardium signal changes in motion corrected free-breathing perfusion images were closely correlated to those observed in breath-hold images. The correlation coefficient is 0.9764 for myocardial signals. Bland-Altman analysis confirmed the agreement between the free-breathing SW-CG-HYPR method with motion correction and the breath-hold SW-CG-HYPR. This technique may allow myocardial perfusion MRI during free breathing.

  5. Can Dynamic Contrast-Enhanced MRI (DCE-MRI) and Diffusion-Weighted MRI (DW-MRI) Evaluate Inflammation Disease

    PubMed Central

    Zhu, Jianguo; Zhang, Faming; Luan, Yun; Cao, Peng; Liu, Fei; He, Wenwen; Wang, Dehang

    2016-01-01

    Abstract The aim of the study was to investigate diagnosis efficacy of dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted MRI (DW-MRI) in Crohn's disease (CD). To find out the correlations between functional MRI parameters including Ktrans, Kep, Ve, Vp, and apparent diffusion coefficient (ADC) with a serologic biomarker. The relationships between pharmacokinetic parameters and ADC were also studied. Thirty-two patients with CD (22 men, 10 women; mean age: 30.5 years) and 18 healthy volunteers without any inflammatory disease (10 men, 8 women; mean age, 34.11 years) were enrolled into this approved prospective study. Pearson analysis was used to evaluate the correlation between Ktrans, Kep, Ve, Vp, and C-reactive protein (CRP), ADC, and CRP respectively. The diagnostic efficacy of the functional MRI parameters in terms of sensitivity and specificity were analyzed by receiver operating characteristic (ROC) curve analyses. Optimal cut-off values of each functional MRI parameters for differentiation of inflammatory from normal bowel were determined according to the Youden criterion. Mean value of Ktrans in the CD group was significantly higher than that of normal control group. Similar results were observed for Kep and Ve. On the contrary, the ADC value was lower in the CD group than that in the control group. Ktrans and Ve were shown to be correlated with CRP (r = 0.725, P < 0.001; r = 0.533, P = 0.002), meanwhile ADC showed negative correlation with CRP (r = −0.630, P < 0.001). There were negative correlations between the pharmacokinetic parameters and ADC, such as Ktrans to ADC (r = −0.856, P < 0.001), and Ve to ADC (r = −0.451, P = 0.01). The area under the curve (AUC) was 0.994 for Ktrans (P < 0.001), 0.905 for ADC (P < 0.001), 0.806 for Ve (P < 0.001), and 0.764 for Kep (P = 0.002). The cut-off point of the Ktrans was found to be 0.931 min–1. This value provided the best trade-off between

  6. Correlation of oxygenation and perfusion sensitive MRI with invasive micro probe measurements in healthy mice brain.

    PubMed

    Sedlacik, Jan; Reitz, Matthias; Bolar, Divya S; Adalsteinsson, Elfar; Schmidt, Nils O; Fiehler, Jens

    2015-03-01

    The non-invasive assessment of (patho-)physiological parameters such as, perfusion and oxygenation, is of great importance for the characterization of pathologies e.g., tumors, which may be helpful to better predict treatment response and potential outcome. To better understand the influence of physiological parameters on the investigated oxygenation and perfusion sensitive MRI methods, MRI measurements were correlated with subsequent invasive micro probe measurements during free breathing conditions of air, air+10% CO2 and 100% O2 in healthy mice brain. MRI parameters were the irreversible (R2), reversible (R2') and effective (R2*) transverse relaxation rates, venous blood oxygenation level assessed by quantitative blood oxygenation level dependent (qBOLD) method and cerebral blood flow (CBF) assessed by arterial spin labeling (ASL) using a 7 T small animal MRI scanner. One to two days after MRI, tissue perfusion and pO2 were measured by Laser-Doppler flowmetry and fluorescence quenching micro probes, respectively. The tissue pO2 values were converted to blood oxygen saturation by using the Hill equation. The animals were anesthetized by intra peritoneal injection of ketamine-xylazine-acepromazine (10-2-0.3 mg/ml · kg). Results for normal/hypercapnia/hyperoxia conditions were: R2[s(∧)-1] = 20.7/20.4/20.1, R2*[s(∧)-1] = 31.6/29.6/25.9, R2'[s-(∧)1] = 10.9/9.2/5.7, qBOLD venous blood oxygenation level = 0.43/0.51/0.56, CBF[ml · min(∧)-1 · 100 g(∧)-1] = 70.6/105.5/81.8, Laser-Doppler flowmetry[a.u.] = 89.2/120.2/90.6 and pO2[mmHg] = 6.3/32.3/46.7. All parameters were statistically significantly different with P < 0.001 between all breathing conditions. All MRI and the corresponding micro probe measurements were also statistically significantly (P ≤ 0.03) correlated with each other. However, converting the tissue pO2 to blood oxygen saturation = 0.02/0.34/0.63, showed only very limited agreement with the qBOLD venous blood oxygenation level. We found

  7. Minimum Field Strength Simulator for Proton Density Weighted MRI

    PubMed Central

    Chen, Weiyi; Nayak, Krishna S.

    2016-01-01

    Objective To develop and evaluate a framework for simulating low-field proton-density weighted MRI acquisitions based on high-field acquisitions, which could be used to predict the minimum B0 field strength requirements for MRI techniques. This framework would be particularly useful in the evaluation of de-noising and constrained reconstruction techniques. Materials and Methods Given MRI raw data, lower field MRI acquisitions can be simulated based on the signal and noise scaling with field strength. Certain assumptions are imposed for the simulation and their validity is discussed. A validation experiment was performed using a standard resolution phantom imaged at 0.35 T, 1.5 T, 3 T, and 7 T. This framework was then applied to two sample proton-density weighted MRI applications that demonstrated estimation of minimum field strength requirements: real-time upper airway imaging and liver proton-density fat fraction measurement. Results The phantom experiment showed good agreement between simulated and measured images. The SNR difference between simulated and measured was ≤ 8% for the 1.5T, 3T, and 7T cases which utilized scanners with the same geometry and from the same vendor. The measured SNR at 0.35T was 1.8- to 2.5-fold less than predicted likely due to unaccounted differences in the RF receive chain. The predicted minimum field strength requirements for the two sample applications were 0.2 T and 0.3 T, respectively. Conclusions Under certain assumptions, low-field MRI acquisitions can be simulated from high-field MRI data. This enables prediction of the minimum field strength requirements for a broad range of MRI techniques. PMID:27136334

  8. Parkinson's disease-related perfusion and glucose metabolic brain patterns identified with PCASL-MRI and FDG-PET imaging

    PubMed Central

    Teune, Laura K.; Renken, Remco J.; de Jong, Bauke M.; Willemsen, Antoon T.; van Osch, Matthias J.; Roerdink, Jos B.T.M.; Dierckx, Rudi A.; Leenders, Klaus L.

    2014-01-01

    Introduction Under normal conditions, the spatial distribution of resting cerebral blood flow and cerebral metabolic rate of glucose are closely related. A relatively new magnetic resonance (MR) technique, pseudo-continuous arterial spin labeling (PCASL), can be used to measure regional brain perfusion. We identified a Parkinson's disease (PD)-related perfusion and metabolic covariance pattern in the same patients using PCASL and FDG-PET imaging and assessed (dis)similarities in the disease-related pattern between perfusion and metabolism in PD patients. Methods Nineteen PD patients and seventeen healthy controls underwent [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging. Of 14 PD patients and all healthy controls PCASL-MRI could be obtained. Data were analyzed using scaled subprofile model/principal component analysis (SSM/PCA). Results Unique Parkinson's disease-related perfusion and metabolic covariance patterns were identified using PCASL and FDG-PET in the same patients. The PD-related metabolic covariance brain pattern is in high accordance with previously reports. Also our disease-related perfusion pattern is comparable to the earlier described perfusion pattern. The most marked difference between our perfusion and metabolic patterns is the larger perfusion decrease in cortical regions including the insula. Conclusion We identified PD-related perfusion and metabolic brain patterns using PCASL and FDG-PET in the same patients which were comparable with results of existing research. In this respect, PCASL appears to be a promising addition in the early diagnosis of individual parkinsonian patients. PMID:25068113

  9. Resolution of NASH with weight loss documented by hepatic MRI.

    PubMed

    Singh, Vasvi; Luthra, Saurav; Elajami, Tarec K; Welty, Francine K

    2015-01-06

    A 57-year-old Asian woman with type 2 diabetes mellitus, hypertension, obesity, dyslipidaemia and history of breast cancer, was referred to the cardiovascular health and lipid centre for evaluation and management of dyslipidaemia and NASH (Non-alcoholic steatohepatitis) in 2010. She originally had a detailed work up at the liver clinic for elevated liver enzymes, with no associated symptoms. Initial hepatic MRI on 22 January 2007 showed diffuse fatty infiltration quantitated at 15%. We counselled her on lifestyle modifications, including dietary measures and exercise, geared toward weight loss. Over the next 2 years, she lost 24.5 lbs; repeat hepatic MRI on 22 December 2011 showed 6% hepatic fat, which is within the normal range. This case demonstrates the efficacy of significant weight loss in the improvement and resolution of NASH. We believe that this is the first case report documenting this through liver MRI.

  10. Resolution of NASH with weight loss documented by hepatic MRI

    PubMed Central

    Singh, Vasvi; Luthra, Saurav; Elajami, Tarec K; Welty, Francine K

    2015-01-01

    A 57-year-old Asian woman with type 2 diabetes mellitus, hypertension, obesity, dyslipidaemia and history of breast cancer, was referred to the cardiovascular health and lipid centre for evaluation and management of dyslipidaemia and NASH (Non-alcoholic steatohepatitis) in 2010. She originally had a detailed work up at the liver clinic for elevated liver enzymes, with no associated symptoms. Initial hepatic MRI on 22 January 2007 showed diffuse fatty infiltration quantitated at 15%. We counselled her on lifestyle modifications, including dietary measures and exercise, geared toward weight loss. Over the next 2 years, she lost 24.5 lbs; repeat hepatic MRI on 22 December 2011 showed 6% hepatic fat, which is within the normal range. This case demonstrates the efficacy of significant weight loss in the improvement and resolution of NASH. We believe that this is the first case report documenting this through liver MRI. PMID:25564638

  11. Accelerating free breathing myocardial perfusion MRI using multi coil radial k-t SLR

    PubMed Central

    Lingala, Sajan Goud; DiBella, Edward; Adluru, Ganesh; McGann, Christopher; Jacob, Mathews

    2013-01-01

    The clinical utility of myocardial perfusion MR imaging (MPI) is often restricted by the inability of current acquisition schemes to simultaneously achieve high spatio-temporal resolution, good volume coverage, and high signal to noise ratio. Moreover, many subjects often find it difficult to hold their breath for sufficiently long durations making it difficult to obtain reliable MPI data. Accelerated acquisition of free breathing MPI data can overcome some of these challenges. Recently, an algorithm termed as k − t SLR has been proposed to accelerate dynamic MRI by exploiting sparsity and low rank properties of dynamic MRI data. The main focus of this paper is to further improve k − t SLR and demonstrate its utility in considerably accelerating free breathing MPI. We extend its previous implementation to account for multi-coil radial MPI acquisitions. We perform k − t sampling experiments to compare different radial trajectories and determine the best sampling pattern. We also introduce a novel augmented Lagrangian framework to considerably improve the algorithm's convergence rate. The proposed algorithm is validated using free breathing rest and stress radial perfusion data sets from two normal subjects and one patient with ischemia. k − t SLR was observed to provide faithful reconstructions at high acceleration levels with minimal artifacts compared to existing MPI acceleration schemes such as spatio-temporal constrained reconstruction (STCR) and k − t SPARSE/SENSE. PMID:24077063

  12. Diagnosis of pseudoprogression using MRI perfusion in patients with glioblastoma multiforme may predict improved survival

    PubMed Central

    Gahramanov, Seymur; Varallyay, Csanad; Tyson, Rose Marie; Lacy, Cynthia; Fu, Rongwei; Netto, Joao Prola; Nasseri, Morad; White, Tricia; Woltjer, Randy L; Gultekin, Sakir Humayun; Neuwelt, Edward A

    2015-01-01

    SUMMARY Aims This retrospective study determined the survival of glioblastoma patients with or without pseudoprogression. Methods A total of 68 patients were included. Overall survival was compared between patients showing pseudoprogression (in most cases diagnosed using perfusion MRI with ferumoxytol) and in patients without pseudoprogession. MGMT methylation status was also analyzed in the pseudoprogression cases. Results Median survival in 24 (35.3%) patients with pseudoprogression was 34.7 months (95% CI: 20.3–54.1), and 13.4 months (95% CI: 11.1–19.5) in 44 (64.7%) patients without pseudoprogression (p < 0.0001). The longest survival was a median of 54.1 months in patients with combination of pseudoprogression and (MGMT) promoter methylation. Conclusion Pseudoprogression is associated with better outcome, especially if concurring with MGMT promoter methylation. Patients never diagnosed with pseudoprogression had poor survival. This study emphasizes the importance of differentiating tumor progression and pseudoprogression using perfusion MRI. PMID:25438810

  13. Cardiac function and myocardial perfusion immediately following maximal treadmill exercise inside the MRI room

    PubMed Central

    Jekic, Mihaela; Foster, Eric L; Ballinger, Michelle R; Raman, Subha V; Simonetti, Orlando P

    2008-01-01

    Treadmill exercise stress testing is an essential tool in the prevention, detection, and treatment of a broad spectrum of cardiovascular disease. After maximal exercise, cardiac images at peak stress are typically acquired using nuclear scintigraphy or echocardiography, both of which have inherent limitations. Although CMR offers superior image quality, the lack of MRI-compatible exercise and monitoring equipment has prevented the realization of treadmill exercise CMR. It is critical to commence imaging as quickly as possible after exercise to capture exercise-induced cardiac wall motion abnormalities. We modified a commercial treadmill such that it could be safely positioned inside the MRI room to minimize the distance between the treadmill and the scan table. We optimized the treadmill exercise CMR protocol in 20 healthy volunteers and successfully imaged cardiac function and myocardial perfusion at peak stress, followed by viability imaging at rest. Imaging commenced an average of 30 seconds after maximal exercise. Real-time cine of seven slices with no breath-hold and no ECG-gating was completed within 45 seconds of exercise, immediately followed by stress perfusion imaging of three short-axis slices which showed an average time to peak enhancement within 57 seconds of exercise. We observed a 3.1-fold increase in cardiac output and a myocardial perfusion reserve index of 1.9, which agree with reported values for healthy subjects at peak stress. This study successfully demonstrates in-room treadmill exercise CMR in healthy volunteers, but confirmation of feasibility in patients with heart disease is still needed. PMID:18272005

  14. Perfusion MRI Indexes Variability in the Functional Brain Effects of Theta-Burst Transcranial Magnetic Stimulation

    PubMed Central

    Gratton, Caterina; Lee, Taraz G.; Nomura, Emi M.; D’Esposito, Mark

    2014-01-01

    Transcranial Magnetic Stimulation (TMS) is an important tool for testing causal relationships in cognitive neuroscience research. However, the efficacy of TMS can be variable across individuals and difficult to measure. This variability is especially a challenge when TMS is applied to regions without well-characterized behavioral effects, such as in studies using TMS on multi-modal areas in intrinsic networks. Here, we examined whether perfusion fMRI recordings of Cerebral Blood Flow (CBF), a quantitative measure sensitive to slow functional changes, reliably index variability in the effects of stimulation. Twenty-seven participants each completed four combined TMS-fMRI sessions during which both resting state Blood Oxygen Level Dependent (BOLD) and perfusion Arterial Spin Labeling (ASL) scans were recorded. In each session after the first baseline day, continuous theta-burst TMS (TBS) was applied to one of three locations: left dorsolateral prefrontal cortex (L dlPFC), left anterior insula/frontal operculum (L aI/fO), or left primary somatosensory cortex (L S1). The two frontal targets are components of intrinsic networks and L S1 was used as an experimental control. CBF changes were measured both before and after TMS on each day from a series of interleaved resting state and perfusion scans. Although TBS led to weak selective increases under the coil in CBF measurements across the group, individual subjects showed wide variability in their responses. TBS-induced changes in rCBF were related to TBS-induced changes in functional connectivity of the relevant intrinsic networks measured during separate resting-state BOLD scans. This relationship was selective: CBF and functional connectivity of these networks were not related before TBS or after TBS to the experimental control region (S1). Furthermore, subject groups with different directions of CBF change after TBS showed distinct modulations in the functional interactions of targeted networks. These results suggest

  15. Effects of cerebral ischemic and reperfusion on T2*-weighted MRI responses to brief oxygen challenge.

    PubMed

    Shen, Qiang; Du, Fang; Huang, Shiliang; Duong, Timothy Q

    2014-01-01

    This study characterized the effects of cerebral ischemia and reperfusion on T2*-weighted magnetic resonance image (MRI) responses to brief oxygen challenge (OC) in transient (60 minutes) cerebral ischemia in rats. During occlusion, the ischemic core tissue showed no significant OC response, whereas the perfusion-diffusion mismatch tissue showed markedly higher percent changes relative to normal tissue. After reperfusion, much of the pixels with initial exaggerated OC responses showed normal OC responses, and the majority of these tissues were salvaged as defined by endpoint T2 MRI. The initial core pixels showed exaggerated OC responses after reperfusion, but the majority of the core pixels eventually became infarct, suggesting exaggerated OC responses do not necessarily reflect salvageable tissue. Twenty-four hours after stroke, basal T1 increased in the ischemic core. Oxygen challenge decreased T1 significantly in the core, indicative of the substantial increases in dissolved oxygen in the core as the result of hyperperfusion. We concluded that exaggerated T2*-weighted MRI responses to OC offer useful insight in ischemic tissue fates. However, exaggerated OC pixels are not all salvageable, and they exhibited complex dynamics depending on reperfusion status, hyperperfusion, and edema effects.

  16. Quantitative Myocardial Perfusion with Dynamic Contrast-Enhanced Imaging in MRI and CT: Theoretical Models and Current Implementation

    PubMed Central

    Handayani, A.; Dijkstra, H.; Prakken, N. H. J.; Slart, R. H. J. A.; Oudkerk, M.; Van Ooijen, P. M. A.; Vliegenthart, R.; Sijens, P. E.

    2016-01-01

    Technological advances in magnetic resonance imaging (MRI) and computed tomography (CT), including higher spatial and temporal resolution, have made the prospect of performing absolute myocardial perfusion quantification possible, previously only achievable with positron emission tomography (PET). This could facilitate integration of myocardial perfusion biomarkers into the current workup for coronary artery disease (CAD), as MRI and CT systems are more widely available than PET scanners. Cardiac PET scanning remains expensive and is restricted by the requirement of a nearby cyclotron. Clinical evidence is needed to demonstrate that MRI and CT have similar accuracy for myocardial perfusion quantification as PET. However, lack of standardization of acquisition protocols and tracer kinetic model selection complicates comparison between different studies and modalities. The aim of this overview is to provide insight into the different tracer kinetic models for quantitative myocardial perfusion analysis and to address typical implementation issues in MRI and CT. We compare different models based on their theoretical derivations and present the respective consequences for MRI and CT acquisition parameters, highlighting the interplay between tracer kinetic modeling and acquisition settings. PMID:27088083

  17. Dynamic contrast-enhanced MRI perfusion for differentiating between melanoma and lung cancer brain metastases.

    PubMed

    Hatzoglou, Vaios; Tisnado, Jamie; Mehta, Alpesh; Peck, Kyung K; Daras, Mariza; Omuro, Antonio M; Beal, Kathryn; Holodny, Andrei I

    2017-04-01

    Brain metastases originating from different primary sites overlap in appearance and are difficult to differentiate with conventional MRI. Dynamic contrast-enhanced (DCE)-MRI can assess tumor microvasculature and has demonstrated utility in characterizing primary brain tumors. Our aim was to evaluate the performance of plasma volume (Vp) and volume transfer coefficient (K(trans) ) derived from DCE-MRI in distinguishing between melanoma and nonsmall cell lung cancer (NSCLC) brain metastases. Forty-seven NSCLC and 23 melanoma brain metastases were retrospectively assessed with DCE-MRI. Regions of interest were manually drawn around the metastases to calculate Vpmean and Kmeantrans. The Mann-Whitney U test and receiver operating characteristic analysis (ROC) were performed to compare perfusion parameters between the two groups. The Vpmean of melanoma brain metastases (4.35, standard deviation [SD] = 1.31) was significantly higher (P = 0.03) than Vpmean of NSCLC brain metastases (2.27, SD = 0.96). The Kmeantrans values were higher in melanoma brain metastases, but the difference between the two groups was not significant (P = 0.12). Based on ROC analysis, a cut-off value of 3.02 for Vpmean (area under curve = 0.659 with SD = 0.074) distinguished between melanoma brain metastases and NSCLC brain metastases (P < 0.01) with 72% specificity. Our data show the DCE-MRI parameter Vpmean can differentiate between melanoma and NSCLC brain metastases. The ability to noninvasively predict tumor histology of brain metastases in patients with multiple malignancies can have important clinical implications.

  18. Diffusion-weighted MRI in neuro-oncology.

    PubMed

    Baehring, Joachim M; Fulbright, Robert K

    2012-11-01

    Diffusion-weighted MRI (DW-MRI) provides image contrast dependent on the molecular movement of water. It has been most widely used in the diagnosis of cytotoxic edema secondary to acute cerebral ischemia, but has also proven useful in assessing tumor cellularity and grade, abscess formation, cysts and various forms of white matter disorders. Furthermore, DW-MRI is used to generate maps of subcortical white matter tracts and their relationship to structural brain lesions that may serve for preoperative planning and intraoperative guidance. We provide a comprehensive review of current practical applications of DW-MRI in the diagnosis and treatment of primary brain tumors, metastases and nonmetastatic neurologic complications of cancer. A detailed description of diffusion tensor imaging is beyond the scope of this review. We performed a comprehensive search of the PubMed database of the USA National Library of Medicine with use of various combinations of the following search terms: diffusion-weighted imaging, apparent diffusion coefficient, diffusion tensor imaging, diffusion tensor, brain, tumor, glioblastoma, lymphoma, primary CNS lymphoma, stroke, cancer, abscess, leukoencephalopathy, methotrexate, fluorouracil, capecitabine. We identified original articles and well-documented case reports of DW-MRI applications in patients with primary brain neoplasms, metastases and nonmetastatic neurologic complications that we judged to be of high impact on the field. We largely selected publications from the past 10 years, but did not exclude commonly referenced and highly regarded older publications. We also searched the reference lists of articles identified by this search strategy and selected those we judged relevant. Review articles are cited to provide readers with more details and more references than can be covered here.

  19. The role of susceptibility weighted imaging in functional MRI.

    PubMed

    Haacke, E Mark; Ye, Yongquan

    2012-08-15

    The development of functional brain magnetic resonance imaging (fMRI) has been a boon for neuroscientists and radiologists alike. It provides for fundamental information on brain function and better diagnostic tools to study disease. In this paper, we will review some of the early concepts in high resolution gradient echo imaging with a particular emphasis on susceptibility weighted imaging (SWI) and MR angiography (MRA). We begin with the history of our own experience in this area, followed by a discussion of the role of high resolution in studying the vasculature of the brain and how this relates to the BOLD (blood oxygenation level dependent) signal. We introduce the role of SWI and susceptibility mapping (SWIM) in fMRI and close with recommendations for future high resolution experiments.

  20. Comparison of Arterial Spin Labeling and Bolus Perfusion-Weighted Imaging for Detecting Mismatch in Acute Stroke

    PubMed Central

    Zaharchuk, Greg; El Mogy, Ibraheem S.; Fischbein, Nancy J.; Albers, Gregory W.

    2012-01-01

    PURPOSE The perfusion-weighted imaging (PWI) – diffusion-weighted imaging (DWI) mismatch paradigm is widely used in stroke imaging studies. Arterial spin labeling (ASL) is an alternative perfusion method that does not require contrast. This study compares the agreement of ASL-DWI and PWI-DWI mismatch classification in stroke patients. MATERIALS AND METHODS This was a retrospective study drawn from all 1.5T MRI studies performed in 2010 at a single institution. Inclusion criteria were: symptom onset<5 days, DWI lesion>10 ml, acquisition of both PWI and ASL. DWI and PWI-Tmax>6 sec lesion volumes were determined using automated software. Patients were classified into reperfused, matched, or mismatch groups. Two radiologists classified ASL-DWI qualitatively into the same categories, blinded to DWI-PWI. Agreement between both individual readers and methods was assessed. RESULTS 51 studies met the inclusion criteria. Seven cases were excluded (1 due to PWI susceptibility artifact, 2 due to motion, and 4 due to severe ASL borderzone sign), resulting in 44 studies for comparison. Inter-rater agreement for ASL–DWI mismatch status was high (κ =0.92, 95% CI 0.80–1.00). ASL-DWI and PWI-DWI mismatch categories agreed in 25/44 cases (57%). In the 16 of 19 discrepant cases (84%), ASL overestimated the PWI lesion size. In 34/44 cases (77%), they agreed regarding the presence of mismatch versus no mismatch. CONCLUSION Mismatch classification based on ASL and PWI agree frequently but not perfectly. ASL tends to overestimate the PWI-Tmax lesion volume. Improved ASL methodologies and/or higher field strength are necessary before ASL can be recommended for routine use in acute stroke. PMID:22539548

  1. Perfusion and vascular permeability: basic concepts and measurement in DCE-CT and DCE-MRI.

    PubMed

    Cuenod, C A; Balvay, D

    2013-12-01

    The microvascular network formed by the capillaries supplies the tissues and permits their function. It provides a considerable surface area for exchanges between blood and tissues. All pathological conditions cause changes in the microcirculation. These changes can be used as imaging biomarkers for the diagnosis of lesions and optimisation of treatment. Among the many imaging techniques developed to study the microcirculation, the analysis of the tissue kinetics of intravenously injected contrast agents is the most widely used, either as positive enhancement for CT, T1-weighted MRI and ultrasound - dynamic contrast-enhanced-imaging (DCE-imaging) - or negative enhancement in T2*-weighted brain MRI - dynamic susceptibility contrast-MRI (DSC-MRI) -. Acquisition involves an injection of contrast agent during the acquisition of a dynamic series of images on a zone of interest. These kinetics may be analyzed visually, to define qualitative criteria, or with software using mathematical modelling, to extract quantitative physiological parameters. The results depend on the acquisition conditions (type of imaging device, imaging mode, frequency and total duration of acquisition), the type of contrast agent, the data pre-processing (motion correction, conversion of the signal into concentration) and the data analysis method. Because of these multiple choices it is necessary to understand the physiological processes involved and understand the advantages and limits of each strategy.

  2. Dissociative Part-Dependent Resting-State Activity in Dissociative Identity Disorder: A Controlled fMRI Perfusion Study

    PubMed Central

    Schlumpf, Yolanda R.; Reinders, Antje A. T. S.; Nijenhuis, Ellert R. S.; Luechinger, Roger; van Osch, Matthias J. P.; Jäncke, Lutz

    2014-01-01

    Background In accordance with the Theory of Structural Dissociation of the Personality (TSDP), studies of dissociative identity disorder (DID) have documented that two prototypical dissociative subsystems of the personality, the “Emotional Part” (EP) and the “Apparently Normal Part” (ANP), have different biopsychosocial reactions to supraliminal and subliminal trauma-related cues and that these reactions cannot be mimicked by fantasy prone healthy controls nor by actors. Methods Arterial spin labeling perfusion MRI was used to test the hypotheses that ANP and EP in DID have different perfusion patterns in response to rest instructions, and that perfusion is different in actors who were instructed to simulate ANP and EP. In a follow-up study, regional cerebral blood flow of DID patients was compared with the activation pattern of healthy non-simulating controls. Results Compared to EP, ANP showed elevated perfusion in bilateral thalamus. Compared to ANP, EP had increased perfusion in the dorsomedial prefrontal cortex, primary somatosensory cortex, and motor-related areas. Perfusion patterns for simulated ANP and EP were different. Fitting their reported role-play strategies, the actors activated brain structures involved in visual mental imagery and empathizing feelings. The follow-up study demonstrated elevated perfusion in the left temporal lobe in DID patients, whereas non-simulating healthy controls had increased activity in areas which mediate the mental construction of past and future episodic events. Conclusion DID involves dissociative part-dependent resting-state differences. Compared to ANP, EP activated brain structures involved in self-referencing and sensorimotor actions more. Actors had different perfusion patterns compared to genuine ANP and EP. Comparisons of neural activity for individuals with DID and non-DID simulating controls suggest that the resting-state features of ANP and EP in DID are not due to imagination. The findings are

  3. MO-G-18C-05: Real-Time Prediction in Free-Breathing Perfusion MRI

    SciTech Connect

    Song, H; Liu, W; Ruan, D; Jung, S; Gach, M

    2014-06-15

    Purpose: The aim is to minimize frame-wise difference errors caused by respiratory motion and eliminate the need for breath-holds in magnetic resonance imaging (MRI) sequences with long acquisitions and repeat times (TRs). The technique is being applied to perfusion MRI using arterial spin labeling (ASL). Methods: Respiratory motion prediction (RMP) using navigator echoes was implemented in ASL. A least-square method was used to extract the respiratory motion information from the 1D navigator. A generalized artificial neutral network (ANN) with three layers was developed to simultaneously predict 10 time points forward in time and correct for respiratory motion during MRI acquisition. During the training phase, the parameters of the ANN were optimized to minimize the aggregated prediction error based on acquired navigator data. During realtime prediction, the trained ANN was applied to the most recent estimated displacement trajectory to determine in real-time the amount of spatial Results: The respiratory motion information extracted from the least-square method can accurately represent the navigator profiles, with a normalized chi-square value of 0.037±0.015 across the training phase. During the 60-second training phase, the ANN successfully learned the respiratory motion pattern from the navigator training data. During real-time prediction, the ANN received displacement estimates and predicted the motion in the continuum of a 1.0 s prediction window. The ANN prediction was able to provide corrections for different respiratory states (i.e., inhalation/exhalation) during real-time scanning with a mean absolute error of < 1.8 mm. Conclusion: A new technique enabling free-breathing acquisition during MRI is being developed. A generalized ANN development has demonstrated its efficacy in predicting a continuum of motion profile for volumetric imaging based on navigator inputs. Future work will enhance the robustness of ANN and verify its effectiveness with human

  4. Quantification of pulmonary blood flow (PBF): validation of perfusion MRI and nonlinear contrast agent (CA) dose correction with H(2)15O positron emission tomography (PET).

    PubMed

    Neeb, Daniel; Kunz, Rainer Peter; Ley, Sebastian; Szábo, Gábor; Strauss, Ludwig G; Kauczor, Hans-Ulrich; Kreitner, Karl-Friedrich; Schreiber, Laura Maria

    2009-08-01

    Validation of quantification of pulmonary blood flow (PBF) with dynamic, contrast-enhanced MRI is still missing. A possible reason certainly lies in difficulties based on the nonlinear dependence of signal intensity (SI) from contrast agent (CA) concentration. Both aspects were addressed in this study. Nine healthy pigs were examined by first-pass perfusion MRI using gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) and H(2)(15)O positron emission tomography (PET) imaging. Calculations of hemodynamic parameters were based on a one-compartment model (MR) and a two-compartment model (PET). Simulations showed a significant error when assuming a linear relation between MR SI and CA dose in the arterial input function (AIF), even at low doses of 0.025 mmol/kg body weight (BW). To correct for nonlinearity, a calibration curve was calculated on the basis of the signal equation. The required accuracy of equation parameters (like longitudinal relaxation time) was evaluated. Error analysis estimates <5% over-/underestimation of the corrected SI. Comparison of PET and MR flow values yielded a significant correlation (P < 0.001) in dorsal regions where signal-to-noise ratio (SNR) was sufficient. Changes in PBF due to the correction method were significant (P < 0.001) and resulted in a better agreement: mean values (standard deviation) in units of ml/min/100 ml lung tissue were 59 (15) for PET, 112 (28) for uncorrected MRI, and 80 (21) for corrected MRI.

  5. Alterations of the Blood-Brain Barrier and Regional Perfusion in Tumor Development: MRI Insights from a Rat C6 Glioma Model

    PubMed Central

    Huhndorf, Monika; Moussavi, Amir; Kramann, Nadine; Will, Olga; Hattermann, Kirsten; Stadelmann, Christine; Jansen, Olav

    2016-01-01

    Objectives Angiogenesis and anti-angiogenetic medications play an important role in progression and therapy of glioblastoma. In this context, in vivo characterization of the blood-brain-barrier and tumor vascularization may be important for individual prognosis and therapy optimization. Methods We analyzed perfusion and capillary permeability of C6-gliomas in rats at different stages of tumor-growth by contrast enhanced MRI and dynamic susceptibility contrast (DSC) MRI at 7 Tesla. The analyses included maps of relative cerebral blood volume (CBV) and signal recovery derived from DSC data over a time period of up to 35 days after tumor cell injections. Results In all rats tumor progression was accompanied by temporal and spatial changes in CBV and capillary permeability. A leakage of the blood-brain barrier (slow contrast enhancement) was observed as soon as the tumor became detectable on T2-weighted images. Interestingly, areas of strong capillary permeability (fast signal enhancement) were predominantly localized in the center of the tumor. In contrast, the tumor rim was dominated by an increased CBV and showed the highest vessel density compared to the tumor center and the contralateral hemisphere as confirmed by histology. Conclusion Substantial regional differences in the tumor highlight the importance of parameter maps in contrast or in addition to region-of-interest analyses. The data vividly illustrate how MRI including contrast-enhanced and DSC-MRI may contribute to a better understanding of tumor development. PMID:28005983

  6. Functional MRI for characterization of renal perfusion impairment and edema formation due to acute kidney injury in different mouse strains

    PubMed Central

    Chen, Rongjun; Gutberlet, Marcel; Jang, Mi-Sun; Meier, Martin; Mengel, Michael; Hartung, Dagmar; Wacker, Frank; Rong, Song; Hueper, Katja

    2017-01-01

    Purpose The purpose was to characterize acute kidney injury (AKI) in C57BL/6 (B6)- and 129/Sv (Sv)-mice by noninvasive measurement of renal perfusion and tissue edema using functional MRI. Methods Different severities of AKI were induced in B6- and Sv-mice by renal ischemia reperfusion injury (IRI). Unilateral clamping of the renal pedicle for 35 min (moderate AKI) or 45 min (severe AKI) was done. MRI (7-Tesla) was performed 1, 7 and 28 days after surgery using a flow alternating inversion recovery (FAIR) arterial spin labeling (ASL) sequence. Maps of perfusion and T1-relaxation time were calculated. Relative MRI-parameters of the IRI kidney compared to the contralateral not-clipped kidney were compared between AKI severities and between mouse strains using unpaired t-tests. In addition, fibrosis was assessed by Masson Trichrome and collagen IV staining. Results After moderate AKI relative perfusion impairment was significantly higher in B6- than in Sv-mice at d7 (55±7% vs. 82±8%, p<0.05) and d28 (76±7% vs. 102±3%, p<0.01). T1-values increased in the early phase after AKI in both mouse strains. T1-increase was more severe after prolonged ischemia times of 45 min compared to 35 min in both mouse strains, measured in the renal cortex and outer stripe of outer medulla. Kidney volume loss (compared to the contralateral kidney) occurred already after 7 days but proceeded markedly towards 4 weeks in severe AKI. Early renal perfusion impairment was predictive for later kidney volume loss. The progression to chronic kidney disease (CKD) in the severe AKI model was similar in both mouse strains as revealed by histology. Conclusion Quantification of renal perfusion and tissue edema by functional MRI allows characterization of strain differences upon AKI. Renal perfusion impairment was stronger in B6- compared to Sv-animals following moderate AKI. Prolonged ischemia times were associated with more severe perfusion impairment and edema formation in the early phase and

  7. Differentiation of recurrent spinal ependymoma from postradiation treatment necrosis through multiparametric PET-MR and perfusion MRI.

    PubMed

    Hojjati, Mojgan; Garg, Vasant; Badve, Chaitra A; Abboud, Salim E; Sloan, Andrew E; Wolansky, Leo J

    A 67-year-old male presented with papilledema and back pain localized to the T10 level. Initial workup revealed multifocal spinal ependymoma which was resected and treated with external beam radiotherapy. Nine years after treatment, the patient had a relapse of back pain, and MRI was inconclusive in distinguishing posttreatment radiation necrosis from recurrent tumor. We present the first described report with the utilization of multiparametric positron emission tomography-magnetic resonance imaging and perfusion MRI to distinguish recurrent spinal ependymoma from radiation necrosis.

  8. A component based noise correction method (CompCor) for BOLD and perfusion based fMRI.

    PubMed

    Behzadi, Yashar; Restom, Khaled; Liau, Joy; Liu, Thomas T

    2007-08-01

    A component based method (CompCor) for the reduction of noise in both blood oxygenation level-dependent (BOLD) and perfusion-based functional magnetic resonance imaging (fMRI) data is presented. In the proposed method, significant principal components are derived from noise regions-of-interest (ROI) in which the time series data are unlikely to be modulated by neural activity. These components are then included as nuisance parameters within general linear models for BOLD and perfusion-based fMRI time series data. Two approaches for the determination of the noise ROI are considered. The first method uses high-resolution anatomical data to define a region of interest composed primarily of white matter and cerebrospinal fluid, while the second method defines a region based upon the temporal standard deviation of the time series data. With the application of CompCor, the temporal standard deviation of resting-state perfusion and BOLD data in gray matter regions was significantly reduced as compared to either no correction or the application of a previously described retrospective image based correction scheme (RETROICOR). For both functional perfusion and BOLD data, the application of CompCor significantly increased the number of activated voxels as compared to no correction. In addition, for functional BOLD data, there were significantly more activated voxels detected with CompCor as compared to RETROICOR. In comparison to RETROICOR, CompCor has the advantage of not requiring external monitoring of physiological fluctuations.

  9. Neural Substrates Associated with Weather-Induced Mood Variability: An Exploratory Study Using ASL Perfusion fMRI

    PubMed Central

    Gillihan, Seth J.; Detre, John A.; Farah, Martha J.; Rao, Hengyi

    2013-01-01

    Daily variations in weather are known to be associated with variations in mood. However, little is known about the specific brain regions that instantiate weather-related mood changes. We used a data-driven approach and ASL perfusion fMRI to assess the neural substrates associated with weather-induced mood variability. The data-driven approach was conducted with mood ratings under various weather conditions (N = 464). Forward stepwise regression was conducted to develop a statistical model of mood as a function of weather conditions. The model results were used to calculate the mood-relevant weather index which served as the covariate in the regression analysis of the resting CBF (N = 42) measured by ASL perfusion fMRI under various weather conditions. The resting CBF activities in the left insula-prefrontal cortex and left superior parietal lobe were negatively correlated (corrected p<0.05) with the weather index, indicating that better mood-relevant weather conditions were associated with lower CBF in these regions within the brain’s emotional network. The present study represents a first step toward the investigation of the effect of natural environment on baseline human brain function, and suggests the feasibility of ASL perfusion fMRI for such study. PMID:24834022

  10. 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.

  11. Perfusion functional MRI reveals cerebral blood flow pattern under psychological stress

    NASA Astrophysics Data System (ADS)

    Wang, Jiongjiong; Rao, Hengyi; Wetmore, Gabriel S.; Furlan, Patricia M.; Korczykowski, Marc; Dinges, David F.; Detre, John A.

    2005-12-01

    Despite the prevalence of stress in everyday life and its impact on happiness, health, and cognition, little is known about the neural substrate of the experience of everyday stress in humans. We use a quantitative and noninvasive neuroimaging technique, arterial spin-labeling perfusion MRI, to measure cerebral blood flow (CBF) changes associated with mild to moderate stress induced by a mental arithmetic task with performance monitoring. Elicitation of stress was verified by self-report of stress and emotional state and measures of heart rate and salivary-cortisol level. The change in CBF induced by the stress task was positively correlated with subjective stress rating in the ventral right prefrontal cortex (RPFC) and left insula/putamen area. The ventral RPFC along with right insula/putamen and anterior cingulate showed sustained activation after task completion in subjects reporting a high stress level during arithmetic tasks. Additionally, variations of baseline CBF in the ventral RPFC and right orbitofrontal cortex were found to correlate with changes in salivary-cortisol level and heart rate caused by undergoing stress tasks. We further demonstrated that the observed right prefrontal activation could not be attributed to increased cognitive demand accompanying stress tasks and extended beyond neural pathways associated with negative emotions. Our results provide neuroimaging evidence that psychological stress induces negative emotion and vigilance and that the ventral RPFC plays a key role in the central stress response. anterior cingulate cortex | arterial spin labeling | right prefrontal cortex

  12. Perfusion MRI in hips with metal-on-metal and metal-on-polyethylene total hip arthroplasty

    PubMed Central

    Anwander, H.; Cron, G. O.; Rakhra, K.

    2016-01-01

    Objectives Hips with metal-on-metal total hip arthroplasty (MoM THA) have a high rate of adverse local tissue reactions (ALTR), often associated with hypersensitivity reactions. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) measures tissue perfusion with the parameter Ktrans (volume transfer constant of contrast agent). Our purpose was 1) to evaluate the feasibility of DCE-MRI in patients with THA and 2) to compare DCE-MRI in patients with MoM bearings with metal-on-polyethylene (MoP) bearings, hypothesising that the perfusion index Ktrans in hips with MoM THA is higher than in hips with MoP THA. Methods In this pilot study, 16 patients with primary THA were recruited (eight MoM, eight MoP). DCE-MRI of the hip was performed at 1.5 Tesla (T). For each patient, Ktrans was computed voxel-by-voxel in all tissue lateral to the bladder. The mean Ktrans for all voxels was then calculated. These values were compared with respect to implant type and gender, and further correlated with clinical parameters. Results There was no significant difference between the two bearing types with both genders combined. However, dividing patients by THA bearing and gender, women with MoM bearings had the highest Ktrans values, exceeding those of women with MoP bearings (0.067 min−1 versus 0.053 min−1; p-value < 0.05) and men with MoM bearings (0.067 min−1 versus 0.034 min−1; p-value < 0.001). Considering only the men, patients with MoM bearings had lower Ktrans than those with MoP bearings (0.034 min−1 versus 0.046 min−1; p < 0.05). Conclusion DCE-MRI is feasible to perform in tissues surrounding THA. Females with MoM THA show high Ktrans values in DCE-MRI, suggesting altered tissue perfusion kinematics which may reflect relatively greater inflammation. Cite this article: Dr P. E. Beaule. Perfusion MRI in hips with metal-on-metal and metal-on-polyethylene total hip arthroplasty: A pilot stud. Bone Joint Res 2016;5:73–79. DOI: 10

  13. Simultaneous myocardial strain and dark-blood perfusion imaging using a displacement-encoded MRI pulse sequence.

    PubMed

    Le, Yuan; Stein, Ashley; Berry, Colin; Kellman, Peter; Bennett, Eric E; Taylor, Joni; Lucas, Katherine; Kopace, Rael; Chefd'Hotel, Christophe; Lorenz, Christine H; Croisille, Pierre; Wen, Han

    2010-09-01

    The purpose of this study is to develop and evaluate a displacement-encoded pulse sequence for simultaneous perfusion and strain imaging. Displacement-encoded images in two to three myocardial slices were repeatedly acquired using a single-shot pulse sequence for 3 to 4 min, which covers a bolus infusion of Gadolinium contrast. The magnitudes of the images were T(1) weighted and provided quantitative measures of perfusion, while the phase maps yielded strain measurements. In an acute coronary occlusion swine protocol (n = 9), segmental perfusion measurements were validated against microsphere reference standard with a linear regression (slope 0.986, R(2) = 0.765, Bland-Altman standard deviation = 0.15 mL/min/g). In a group of ST-elevation myocardial infarction patients (n = 11), the scan success rate was 76%. Short-term contrast washout rate and perfusion are highly correlated (R(2) = 0.72), and the pixelwise relationship between circumferential strain and perfusion was better described with a sigmoidal Hill curve than linear functions. This study demonstrates the feasibility of measuring strain and perfusion from a single set of images.

  14. Simultaneous Myocardial Strain and Dark-Blood Perfusion Imaging Using a Displacement-Encoded MRI Pulse Sequence

    PubMed Central

    Le, Yuan; Stein, Ashley; Berry, Colin; Kellman, Peter; Bennett, Eric E.; Taylor, Joni; Lucas, Katherine; Kopace, Rael; Chefd’Hotel, Christophe; Lorenz, Christine H.; Croisille, Pierre; Wen, Han

    2010-01-01

    The purpose of this study is to develop and evaluate a displacement-encoded pulse sequence for simultaneous perfusion and strain imaging. Displacement-encoded images in 2–3 myocardial slices were repeatedly acquired using a single shot pulse sequence for 3 to 4 minutes, which covers a bolus infusion of Gd. The magnitudes of the images were T1 weighted and provided quantitative measures of perfusion, while the phase maps yielded strain measurements. In an acute coronary occlusion swine protocol (n=9), segmental perfusion measurements were validated against microsphere reference standard with a linear regression (slope 0.986, R2 = 0.765, Bland-Altman standard deviation = 0.15 ml/min/g). In a group of ST-elevation myocardial infarction(STEMI) patients (n=11), the scan success rate was 76%. Short-term contrast washout rate and perfusion are highly correlated (R2=0.72), and the pixel-wise relationship between circumferential strain and perfusion was better described with a sigmoidal Hill curve than linear functions. This study demonstrates the feasibility of measuring strain and perfusion from a single set of images. PMID:20544714

  15. DCE-MRI Perfusion and Permeability Parameters as predictors of tumor response to CCRT in Patients with locally advanced NSCLC

    PubMed Central

    Tao, Xiuli; Wang, Lvhua; Hui, Zhouguang; Liu, Li; Ye, Feng; Song, Ying; Tang, Yu; Men, Yu; Lambrou, Tryphon; Su, Zihua; Xu, Xiao; Ouyang, Han; Wu, Ning

    2016-01-01

    In this prospective study, 36 patients with stage III non-small cell lung cancers (NSCLC), who underwent dynamic contrast-enhanced MRI (DCE-MRI) before concurrent chemo-radiotherapy (CCRT) were enrolled. Pharmacokinetic analysis was carried out after non-rigid motion registration. The perfusion parameters [including Blood Flow (BF), Blood Volume (BV), Mean Transit Time (MTT)] and permeability parameters [including endothelial transfer constant (Ktrans), reflux rate (Kep), fractional extravascular extracellular space volume (Ve), fractional plasma volume (Vp)] were calculated, and their relationship with tumor regression was evaluated. The value of these parameters on predicting responders were calculated by receiver operating characteristic (ROC) curve. Multivariate logistic regression analysis was conducted to find the independent variables. Tumor regression rate is negatively correlated with Ve and its standard variation Ve_SD and positively correlated with Ktrans and Kep. Significant differences between responders and non-responders existed in Ktrans, Kep, Ve, Ve_SD, MTT, BV_SD and MTT_SD (P < 0.05). ROC indicated that Ve < 0.24 gave the largest area under curve of 0.865 to predict responders. Multivariate logistic regression analysis also showed Ve was a significant predictor. Baseline perfusion and permeability parameters calculated from DCE-MRI were seen to be a viable tool for predicting the early treatment response after CCRT of NSCLC. PMID:27762331

  16. Using Perfusion fMRI to Measure Continuous Changes in Neural Activity with Learning

    ERIC Educational Resources Information Center

    Olson, Ingrid R.; Rao, Hengyi; Moore, Katherine Sledge; Wang, Jiongjiong; Detre, John A.; Aguirre, Geoffrey K.

    2006-01-01

    In this study, we examine the suitability of a relatively new imaging technique, "arterial spin labeled perfusion imaging," for the study of continuous, gradual changes in neural activity. Unlike BOLD imaging, the perfusion signal is stable over long time-scales, allowing for accurate assessment of continuous performance. In addition, perfusion…

  17. Dynamic contrast-enhanced MRI as a valuable non-invasive tool to evaluate tissue perfusion of free flaps: Preliminary results.

    PubMed

    Fellner, Claudia; Jung, Ernst M; Prantl, Lukas

    2010-01-01

    Early detection of a compromised circulation of free flaps and an immediate revision may lead to higher rates of flap salvage. The aim of this study was to evaluate the perfusion of the entire flap using dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). DCE was performed in 11 patients after flap transplantation using an optimized 3D gradient echo sequence to cover the whole flap. The percentage increase of signal intensity over time was evaluated for the free flap as well as for a reference tissue. Furthermore, normalized signal increase was calculated as the ratio of signal increase within the flaps to the signal increase in the reference tissue. Signal increase in free flaps and reference tissue was compared using the Wilcoxon-test (p < 0.05), normalized signal increase in normally perfused (n = 9) and in flaps with compromised perfusion (n = 2) using Mann-Whitney-test (p < 0.05). Signal increase within normally perfused flaps was similar to the reference tissue. In flaps with compromised perfusion the increase was significantly lower than in reference tissue. Normalized signal increase in adequately perfused flaps and flaps with compromised perfusion also showed a significant difference. DCE MRI may be a valuable non-invasive tool to evaluate tissue perfusion of the complete free flap.

  18. Longitudinal assessment of renal perfusion and oxygenation in transplant donor-recipient pairs using ASL and BOLD MRI

    PubMed Central

    Niles, David J; Artz, Nathan S; Djamali, Arjang; Sadowski, Elizabeth A; Grist, Thomas M; Fain, Sean B

    2015-01-01

    Objectives To assess renal function in kidney transplant recipients and their respective donors over two years using arterial spin labeling (ASL) and blood oxygen level-dependent (BOLD) MRI, and to prospectively evaluate the effect of losartan on functional MRI measures in recipients. Materials and Methods The study included 15 matched pairs of renal transplant donors and recipients. ASL and BOLD MRI of the kidneys were performed on donors prior to transplant surgery (baseline) and on both donors and recipients at 3 months, 1 year and 2 years post-transplant. After 3 months, seven of the 15 recipients were prescribed 25–50 mg/day losartan for the remainder of the study. A linear mixed-effects model was used to evaluate perfusion, R2*, estimated glomerular filtration rate (eGFR), and fractional excretion of sodium (FENa) for changes across time or associated with losartan treatment. Results In donors, cortical perfusion in the remaining kidney decreased by 50 ± 19 ml/min/100g (11.8%) between baseline and 2 years (P < 0.05), while cortical R2* declined modestly by 0.7 ± 0.3 s−1 (5.6%; P < 0.05). In transplanted kidneys, cortical perfusion decreased markedly by 141 ± 21 ml/min/100g (34.2%) between baseline and 2 years (P < 0.001), while medullary R2* declined by 1.5 ± 0.8 s−1 (8.3%; P = 0.06). Single-kidney eGFR increased between baseline and 2 years by 17.7 ± 2.7 ml/min/1.73m2 (40.3%; P < 0.0001) in donors and to 14.6 ± 4.3 ml/min/1.73m2 (33.3%; P < 0.01) in recipients. Cortical perfusion at 1 and 2 years in recipients receiving 25–50 mg/day losartan was 62 ± 24 ml/min/100g higher than recipients not receiving the drug (P < 0.05). No significant effects of losartan were observed for any other markers of renal function. Conclusions The results suggest an important role for non-invasive functional monitoring with ASL and BOLD MRI in kidney transplant recipients and donors, and they indicate a potentially beneficial effect of losartan in recipients. PMID

  19. Robust dynamic myocardial perfusion CT deconvolution using adaptive-weighted tensor total variation regularization

    NASA Astrophysics Data System (ADS)

    Gong, Changfei; Zeng, Dong; Bian, Zhaoying; Huang, Jing; Zhang, Xinyu; Zhang, Hua; Lu, Lijun; Feng, Qianjin; Liang, Zhengrong; Ma, Jianhua

    2016-03-01

    Dynamic myocardial perfusion computed tomography (MPCT) is a promising technique for diagnosis and risk stratification of coronary artery disease by assessing the myocardial perfusion hemodynamic maps (MPHM). Meanwhile, the repeated scanning of the same region results in a relatively large radiation dose to patients potentially. In this work, we present a robust MPCT deconvolution algorithm with adaptive-weighted tensor total variation regularization to estimate residue function accurately under the low-dose context, which is termed `MPD-AwTTV'. More specifically, the AwTTV regularization takes into account the anisotropic edge property of the MPCT images compared with the conventional total variation (TV) regularization, which can mitigate the drawbacks of TV regularization. Subsequently, an effective iterative algorithm was adopted to minimize the associative objective function. Experimental results on a modified XCAT phantom demonstrated that the present MPD-AwTTV algorithm outperforms and is superior to other existing deconvolution algorithms in terms of noise-induced artifacts suppression, edge details preservation and accurate MPHM estimation.

  20. Influence of perfusion on high-intensity focused ultrasound prostate ablation: a first-pass MRI study.

    PubMed

    Wiart, Marlène; Curiel, Laura; Gelet, Albert; Lyonnet, Denis; Chapelon, Jean-Yves; Rouvière, Olivier

    2007-07-01

    Our aim was to evaluate the influence of regional prostate blood flow (rPBF) on high-intensity focused ultrasound (HIFU) treatment outcome. A total of 48 patients with clinically localized prostate cancer were examined by dynamic contrast-enhanced (DCE)-MRI prior to HIFU therapy. A prostate-specific antigen (PSA) nadir threshold of 0.2 ng/ml was used to define the populations of responders and nonresponders. A dedicated tracer kinetic model, namely "monoexponential plus constant" (MPC) deconvolution, was implemented to provide quantitative estimates of rPBF. The results were compared with those obtained by semiquantitative (steepest slope, mean gradient) and quantitative (Fermi deconvolution) approaches. Of the four methods studied, quantitative rPBF obtained by MPC deconvolution proved the most sensitive to the perfusion changes encountered in this study. Furthermore, blood-flow values obtained with MPC deconvolution in the prostate and muscle (12 +/- 8 and 5 +/- 3 ml/min/100 g, respectively) were in good agreement with literature data. The mean pretreatment rPBF obtained with MPC deconvolution was significantly higher in nonresponders compared to responders (16 +/- 9 vs. 10 +/- 6 ml/min/100 g), suggesting a correlation between baseline perfusion and treatment outcome. The present work describes and validates the use of dynamic MRI to estimate rPBF in patients, which in the future may help to refine the conduct of HIFU therapy.

  1. Quantification of myocardial perfusion based on signal intensity of flow sensitized MRI

    NASA Astrophysics Data System (ADS)

    Abeykoon, Sumeda B.

    The quantitative assessment of perfusion is important for early recognition of a variety of heart diseases, determination of disease severity and their cure. In conventional approach of measuring cardiac perfusion by arterial spin labeling, the relative difference in the apparent T1 relaxation times in response to selective and non-selective inversion of blood entering the region of interest is related to perfusion via a two-compartment tissue model. But accurate determination of T1 in small animal hearts is difficult and prone to errors due to long scan times. The purpose of this study is to develop a fast, robust and simple method to quantitatively assess myocardial perfusion using arterial spin labeling. The proposed method is based on signal intensities (SI) of inversion recovery slice-select, non-select and steady-state images. Especially in this method data are acquired at a single inversion time and at short repetition times. This study began by investigating the accuracy of assessment of perfusion using a two compartment system. First, determination of perfusion by T1 and SI were implemented to a simple, two-compartment phantom model. Mathematical model developed for full spin exchange models (in-vivo experiments) by solving a modified Bloch equation was modified to develop mathematical models (T1 and SI) for a phantom (zero spin exchange). The phantom result at different flow rates shows remarkable evidence of accuracy of the two-compartment model and SI, T1 methods: the SI method has less propagation error and less scan time. Next, twelve healthy C57BL/6 mice were scanned for quantitative perfusion assessment and three of them were repeatedly scanned at three different time points for a reproducibility test. The myocardial perfusion of healthy mice obtained by the SI-method, 5.7+/-1.6 ml/g/min, was similar (p=0.38) to that obtained by the conventional T1 method, 5.6+/- 2.3 ml/g/min. The reproducibility of the SI method shows acceptable results: the

  2. Comparison of dynamic susceptibility contrast-MRI perfusion quantification methods in the presence of delay and dispersion

    NASA Astrophysics Data System (ADS)

    Maan, Bianca; Simões, Rita Lopes; Meijer, Frederick J. A.; Klaas Jan Renema, W.; Slump, Cornelis H.

    2011-03-01

    The perfusion of the brain is essential to maintain brain function. Stroke is an example of a decrease in blood flow and reduced perfusion. During ischemic stroke the blood flow to tissue is hampered due to a clot inside a vessel. To investigate the recovery of stroke patients, follow up studies are necessary. MRI is the preferred imaging modality for follow up because of the absence of radiation dose concerns, contrary to CT. Dynamic Susceptibility Contrast (DSC) MRI is an imaging technique used for measuring perfusion of the brain, however, is not standard applied in the clinical routine due to lack of immediate patient benefit. Several post processing algorithms are described in the literature to obtain cerebral blood flow (CBF). The quantification of CBF relies on the deconvolution of a tracer concentration-time curve in an arterial and a tissue voxel. There are several methods to obtain this deconvolution based on singular-value decomposition (SVD). This contribution describes a comparison between the different approaches as currently there is no best practice for (all) clinical relevant situations. We investigate the influence of tracer delay, dispersion and recirculation on the performance of the methods. In the presence of negative delays, the truncated SVD approach overestimates the CBF. Block-circulant and reformulated SVD are delay-independent. Due to its delay dependent behavior, the truncated SVD approach performs worse in the presence of dispersion as well. However all SVD approaches are dependent on the amount of dispersion. Moreover, we observe that the optimal truncation parameter varies when recirculation is added to noisy data, suggesting that, in practice, these methods are not immune to tracer recirculation. Finally, applying the methods to clinical data resulted in a large variability of the CBF estimates. Block-circulant SVD will work in all situations and is the method with the highest potential.

  3. A patient-specific visualization tool for comprehensive analysis of coronary CTA and perfusion MRI data

    NASA Astrophysics Data System (ADS)

    Kirisli, H. A.; Gupta, V.; Kirschbaum, S.; Neefjes, L.; van Geuns, R. J.; Mollet, N.; Lelieveldt, B. P. F.; Reiber, J. H. C.; van Walsum, T.; Niessen, W. J.

    2011-03-01

    Cardiac magnetic resonance perfusion imaging (CMR) and computed tomography angiography (CTA) are widely used to assess heart disease. CMR is used to measure the global and regional myocardial function and to evaluate the presence of ischemia; CTA is used for diagnosing coronary artery disease, such as coronary stenoses. Nowadays, the hemodynamic significance of coronary artery stenoses is determined subjectively by combining information on myocardial function with assumptions on coronary artery territories. As the anatomy of coronary arteries varies greatly between individuals, we developed a patient-specific tool for relating CTA and perfusion CMR data. The anatomical and functional information extracted from CTA and CMR data are combined into a single frame of reference. Our graphical user interface provides various options for visualization. In addition to the standard perfusion Bull's Eye Plot (BEP), it is possible to overlay a 2D projection of the coronary tree on the BEP, to add a 3D coronary tree model and to add a 3D heart model. The perfusion BEP, the 3D-models and the CTA data are also interactively linked. Using the CMR and CTA data of 14 patients, our tool directly established a spatial correspondence between diseased coronary artery segments and myocardial regions with abnormal perfusion. The location of coronary stenoses and perfusion abnormalities were visualized jointly in 3D, thereby facilitating the study of the relationship between the anatomic causes of a blocked artery and the physiological effects on the myocardial perfusion. This tool is expected to improve diagnosis and therapy planning of early-stage coronary artery disease.

  4. Pyogenic abscess from Providencia stuartii mimicking necrotic tumour at perfusion-weighted imaging.

    PubMed

    Muccio, Carmine Franco; Leonini, Sara; Esposito, Gennaro; Cerase, Alfonso

    2011-10-01

    The purpose of this case report is to increase the knowledge about magnetic resonance spectrum of pyogenic abscesses of the brain. A 74-year-old woman presented with a left frontal lobe cystic mass, developed in the site of post-traumatic contusions after surgical evacuation of a subdural hematoma. MR imaging showed an ipsilateral mass lesion with a thin, regular rim of T1 high-intensity signal, T2 low-intensity signal, and gadolinium-enhancement. Diffusion-weighted imaging with measure of apparent diffusion coefficient value showed inhomogenous diffusion restriction in the lesion core. Perfusion-weighted imaging (PWI) demonstrated high relative cerebral blood volume (rCBV) in both the lesion wall and perilesional area, with a maximal rCBV ratio (rCBV of the lesion/rCBV of the normal contralateral white matter) of 5.65 and 0.58, respectively. As a result, surgery and pathology showed a pyogenic abscess. Cultures grew were Providencia stuartii species. In conclusion, a pyogenic brain abscess from P. stuartii may show high rCBV at PWI, thus mimicking a necrotic tumour.

  5. Decreased Cerebral Blood Flow in Chronic Pediatric Mild TBI: An MRI Perfusion Study

    PubMed Central

    Wang, Yang; West, John D.; Bailey, Jessica N.; Westfall, Daniel R.; Xiao, Hui; Arnold, Todd W.; Kersey, Patrick A.; Saykin, Andrew J.; McDonald, Brenna C.

    2015-01-01

    We evaluated cerebral blood flow (CBF) in chronic pediatric mild traumatic brain injury (mTBI) using arterial spin labeling (ASL) magnetic resonance imaging perfusion. mTBI patients showed lower CBF than controls in bilateral frontotemporal regions, with no between-group cognitive differences. Findings suggest ASL may be useful to assess functional abnormalities in pediatric mTBI. PMID:25649779

  6. Perfusion MRI as the predictive/prognostic and pharmacodynamic biomarkers in recurrent malignant glioma treated with bevacizumab: a systematic review and a time-to-event meta-analysis.

    PubMed

    Choi, Sang Hyun; Jung, Seung Chai; Kim, Kyung Won; Lee, Ja Youn; Choi, Yoonseok; Park, Seong Ho; Kim, Ho Sung

    2016-06-01

    This study aims to evaluate the value of perfusion MRI as a predictive/prognostic biomarker and a pharmacodynamic biomarker in patients with recurrent glioma treated with a bevacizumab-based regimen. We identified thirteen literature reports that investigated dynamic susceptibility-contrast (DSC) MRI or dynamic contrast-enhanced (DCE) MRI for predicting the patient outcome and analyzing the anti-angiogenic effect of bevacizumab by performing a systematic search of MEDLINE and EMBASE. The relative cerebral volume (rCBV) of DSC-MRI is currently the most common perfusion MRI parameter used as a predictive/prognostic biomarker. Pooled hazard ratios between responders and non-responders, as determined by rCBV, were 0.46 (95 % CI 0.28-0.76) for progression-free survival from five articles with a total 226 patients and 0.47 (95 % CI 0.29-0.76) for overall survival from six articles with a total 247 patients, and thus indicating that rCBV is helpful for predicting disease progression and the eventual outcome after treatment. Regarding the pharmacodynamic value of perfusion MRI parameters derived from either DSC-MRI or DCE-MRI, most perfusion MRI parameters (rCBV, Ktrans, CBVmax, Kpsmax, fpv, Ve and Kep) demonstrated a consistent decrease on the follow-up MRI after treatment, indicating that perfusion MRI may be helpful for evaluating the anti-angiogenic effect of a bevacizumab-based treatment regimen. However, the lack of standardization of imaging acquisition and analysis techniques for various perfusion MRI parameters needs to be resolved in the future. Despite these unsolved issues, the current evidence favoring the use of perfusion MRI as a predictive/prognostic or pharmacodynamic biomarker should be considered in patients with glioma treated using a bevacizumab-based regimen.

  7. Quantification of in vivo pH-weighted amide proton transfer (APT) MRI in acute ischemic stroke

    NASA Astrophysics Data System (ADS)

    Zhou, Iris Y.; Igarashi, Takahiro; Guo, Yingkun; Sun, Phillip Z.

    2015-03-01

    Amide proton transfer (APT) imaging is a specific form of chemical exchange saturation transfer (CEST) MRI that probes the pH-dependent amide proton exchange.The endogenous APT MRI is sensitive to tissue acidosis, which may complement the commonly used perfusion and diffusion scans for characterizing heterogeneous ischemic tissue damage. Whereas the saturation transfer asymmetry analysis (MTRasym) may reasonably compensate for direct RF saturation, in vivo MTRasym is however, susceptible to an intrinsically asymmetric shift (MTR'asym). Specifically, the reference scan for the endogenous APT MRI is 7 ppm upfield from that of the label scan, and subjects to concomitant RF irradiation effects, including nuclear overhauser effect (NOE)-mediated saturation transfer and semisolid macromolecular magnetization transfer. As such, the commonly used asymmetry analysis could not fully compensate for such slightly asymmetric concomitant RF irradiation effects, and MTRasym has to be delineated in order to properly characterize the pH-weighted APT MRI contrast. Given that there is very little change in relaxation time immediately after ischemia and the concomitant RF irradiation effects only minimally depends on pH, the APT contrast can be obtained as the difference of MTRasym between the normal and ischemic regions. Thereby, the endogenous amide proton concentration and exchange rate can be solved using a dual 2-pool model, and the in vivo MTR'asym can be calculated by subtracting the solved APT contrast from asymmetry analysis (i.e., MTR'asym =MTRasym-APTR). In addition, MTR'asym can be quantified using the classical 2-pool exchange model. In sum, our study delineated the conventional in vivo pH-sensitive MTRasym contrast so that pHspecific contrast can be obtained for imaging ischemic tissue acidosis.

  8. On the Dark Rim Artifact in Dynamic Contrast-Enhanced MRI Myocardial Perfusion Studies

    PubMed Central

    Di Bella, E.V.R.; Parker, D.L.; Sinusas, A.J.

    2008-01-01

    A dark band or rim along parts of the subendocardial border of the left ventricle (LV) and the myocardium has been noticed in some dynamic contrast-enhanced MR perfusion studies. The artifact is thought to be due to susceptibility effects from the gadolinium bolus, motion, or resolution, or a combination of these. Here motionless ex vivo hearts in which the cavity was filled with gadolinium are used to show that dark rim artifacts can be consistent with resolution effects alone. PMID:16200553

  9. Perfusion-weighted imaging and dynamic 4D angiograms for the estimation of collateral blood flow in lacunar infarction.

    PubMed

    Förster, Alex; Mürle, Bettina; Böhme, Johannes; Al-Zghloul, Mansour; Kerl, Hans U; Wenz, Holger; Groden, Christoph

    2016-10-01

    Although lacunar infarction accounts for approximately 25% of ischemic strokes, collateral blood flow through anastomoses is not well evaluated in lacunar infarction. In 111 lacunar infarction patients, we analyzed diffusion-weighted images, perfusion-weighted images, and blood flow on dynamic four-dimensional angiograms generated by use of Signal Processing In NMR-Software. Blood flow was classified as absent (type 1), from periphery to center (type 2), from center to periphery (type 3), and combination of type 2 and 3 (type 4). On diffusion-weighted images, lacunar infarction was found in the basal ganglia (11.7%), internal capsule (24.3%), corona radiata (30.6%), thalamus (24.3%), and brainstem (9.0%). In 58 (52.2%) patients, perfusion-weighted image showed a circumscribed hypoperfusion, in one (0.9%) a circumscribed hyperperfusion, whereas the remainder was normal. In 36 (62.1%) patients, a larger perfusion deficit (>7 mm) was observed. In these, blood flow was classified type 1 in four (11.1%), 2 in 17 (47.2%), 3 in 9 (25.0%), and 4 in six (16.7%) patients. Patients with lacunar infarction in the posterior circulation more often demonstrated blood flow type 2 and less often type 3 (p = 0.01). Detailed examination and graduation of blood flow in lacunar infarction by use of dynamic four-dimensional angiograms is feasible and may serve for a better characterization of this stroke subtype.

  10. Improving cerebral blood flow quantification for arterial spin labeled perfusion MRI by removing residual motion artifacts and global signal fluctuations.

    PubMed

    Wang, Ze

    2012-12-01

    Denoising is critical to improving the quality and stability of cerebral blood flow (CBF) quantification in arterial spin labeled (ASL) perfusion magnetic resonance imaging (MRI) due to the intrinsic low signal-to-noise-ratio (SNR) of ASL data. Previous studies have been focused on reducing the spatial or temporal noise using standard filtering techniques, and less attention has been paid to two global nuisance effects, the residual motion artifacts and the global signal fluctuations. Since both nuisances affect the whole brain, removing them in advance should enhance the CBF quantification quality for ASL MRI. The purpose of this paper was to assess this potential benefit. Three methods were proposed to suppress each or both of the two global nuisances. Their performances for CBF quantification were validated using ASL data acquired from 13 subjects. Evaluation results showed that covarying out both global nuisances significantly improved temporal SNR and test-retest stability of CBF measurement. Although the concept of removing both nuisances is not technically novel per se, this paper clearly showed the benefits for ASL CBF quantification. Dissemination of the proposed methods in a free ASL data processing toolbox should be of interest to a broad range of ASL users.

  11. Complete Separation of Intracellular and Extracellular Information in NMR Spectra of Perfused Cells by Diffusion-Weighted Spectroscopy

    NASA Astrophysics Data System (ADS)

    van Zijl, Peter C. M.; Moonen, Chrit T. W.; Faustino, Patrick; Pekar, James; Kaplan, Ofer; Cohen, Jack S.

    1991-04-01

    A method is outlined that completely separates intracellular and extracellular information in NMR spectra of perfused cells. The technique uses diffusion weighting to exploit differences in motional properties between intra- and extracellular constituents. This allows monitoring of intracellular metabolism, and of transport of small drugs and nutrients through the cell membrane, under controlled physiological conditions. As a first example, proton spectra of drug-resistant MCF-7 human breast cancer cells are studied, and uptake of phenylalanine is monitored.

  12. The Efficiency of Diffusion Weighted MRI and MR Spectroscopy On Breast MR Imaging

    PubMed Central

    Altay, Canan; Balcı, Pınar

    2014-01-01

    The main purpose of breast magnetic resonance imaging (MRI) in radiologically routine is to establish an imaging protocol that will create high quality images with a short period of time. Fort this purpose, an imaging protocol should include a conventional breast MRI and contrast enhanced sequences. Proton MR spectroscopy (MRS) and diffusion weighted imaging (DWI) are important MR techniques for evaluation to complicated breast lesions. In this article, we will evaluate that technical properties of the MRS and DWI as additional MR imaging.

  13. Real Diffusion-Weighted MRI Enabling True Signal Averaging and Increased Diffusion Contrast

    PubMed Central

    Eichner, Cornelius; Cauley, Stephen F; Cohen-Adad, Julien; Möller, Harald E; Turner, Robert; Setsompop, Kawin; Wald, Lawrence L

    2015-01-01

    This project aims to characterize the impact of underlying noise distributions on diffusion-weighted imaging. The noise floor is a well-known problem for traditional magnitude-based diffusion-weighted MRI (dMRI) data, leading to biased diffusion model fits and inaccurate signal averaging. Here, we introduce a total-variation-based algorithm to eliminate shot-to-shot phase variations of complex-valued diffusion data with the intention to extract real-valued dMRI datasets. The obtained real-valued diffusion data are no longer superimposed by a noise floor but instead by a zero-mean Gaussian noise distribution, yielding dMRI data without signal bias. We acquired high-resolution dMRI data with strong diffusion weighting and, thus, low signal-to-noise ratio. Both the extracted real-valued and traditional magnitude data were compared regarding signal averaging, diffusion model fitting and accuracy in resolving crossing fibers. Our results clearly indicate that real-valued diffusion data enables idealized conditions for signal averaging. Furthermore, the proposed method enables unbiased use of widely employed linear least squares estimators for model fitting and demonstrates an increased sensitivity to detect secondary fiber directions with reduced angular error. The use of phase-corrected, real-valued data for dMRI will therefore help to clear the way for more detailed and accurate studies of white matter microstructure and structural connectivity on a fine scale. PMID:26241680

  14. Real diffusion-weighted MRI enabling true signal averaging and increased diffusion contrast.

    PubMed

    Eichner, Cornelius; Cauley, Stephen F; Cohen-Adad, Julien; Möller, Harald E; Turner, Robert; Setsompop, Kawin; Wald, Lawrence L

    2015-11-15

    This project aims to characterize the impact of underlying noise distributions on diffusion-weighted imaging. The noise floor is a well-known problem for traditional magnitude-based diffusion-weighted MRI (dMRI) data, leading to biased diffusion model fits and inaccurate signal averaging. Here, we introduce a total-variation-based algorithm to eliminate shot-to-shot phase variations of complex-valued diffusion data with the intention to extract real-valued dMRI datasets. The obtained real-valued diffusion data are no longer superimposed by a noise floor but instead by a zero-mean Gaussian noise distribution, yielding dMRI data without signal bias. We acquired high-resolution dMRI data with strong diffusion weighting and, thus, low signal-to-noise ratio. Both the extracted real-valued and traditional magnitude data were compared regarding signal averaging, diffusion model fitting and accuracy in resolving crossing fibers. Our results clearly indicate that real-valued diffusion data enables idealized conditions for signal averaging. Furthermore, the proposed method enables unbiased use of widely employed linear least squares estimators for model fitting and demonstrates an increased sensitivity to detect secondary fiber directions with reduced angular error. The use of phase-corrected, real-valued data for dMRI will therefore help to clear the way for more detailed and accurate studies of white matter microstructure and structural connectivity on a fine scale.

  15. Semi-automatic delineation using weighted CT-MRI registered images for radiotherapy of nasopharyngeal cancer

    SciTech Connect

    Fitton, I.; Cornelissen, S. A. P.; Duppen, J. C.; Rasch, C. R. N.; Herk, M. van; Steenbakkers, R. J. H. M.; Peeters, S. T. H.; Hoebers, F. J. P.; Kaanders, J. H. A. M.; Nowak, P. J. C. M.

    2011-08-15

    Purpose: To develop a delineation tool that refines physician-drawn contours of the gross tumor volume (GTV) in nasopharynx cancer, using combined pixel value information from x-ray computed tomography (CT) and magnetic resonance imaging (MRI) during delineation. Methods: Operator-guided delineation assisted by a so-called ''snake'' algorithm was applied on weighted CT-MRI registered images. The physician delineates a rough tumor contour that is continuously adjusted by the snake algorithm using the underlying image characteristics. The algorithm was evaluated on five nasopharyngeal cancer patients. Different linear weightings CT and MRI were tested as input for the snake algorithm and compared according to contrast and tumor to noise ratio (TNR). The semi-automatic delineation was compared with manual contouring by seven experienced radiation oncologists. Results: A good compromise for TNR and contrast was obtained by weighing CT twice as strong as MRI. The new algorithm did not notably reduce interobserver variability, it did however, reduce the average delineation time by 6 min per case. Conclusions: The authors developed a user-driven tool for delineation and correction based a snake algorithm and registered weighted CT image and MRI. The algorithm adds morphological information from CT during the delineation on MRI and accelerates the delineation task.

  16. Altered resting-state functional connectivity in post-traumatic stress disorder: a perfusion MRI study

    NASA Astrophysics Data System (ADS)

    Li, Baojuan; Liu, Jian; Liu, Yang; Lu, Hong-Bing; Yin, Hong

    2013-03-01

    The majority of studies on posttraumatic stress disorder (PTSD) so far have focused on delineating patterns of activations during cognitive processes. Recently, more and more researches have started to investigate functional connectivity in PTSD subjects using BOLD-fMRI. Functional connectivity analysis has been demonstrated as a powerful approach to identify biomarkers of different brain diseases. This study aimed to detect resting-state functional connectivity abnormities in patients with PTSD using arterial spin labeling (ASL) fMRI. As a completely non-invasive technique, ASL allows quantitative estimates of cerebral blood flow (CBF). Compared with BOLD-fMRI, ASL fMRI has many advantages, including less low-frequency signal drifts, superior functional localization, etc. In the current study, ASL images were collected from 10 survivors in mining disaster with recent onset PTSD and 10 survivors without PTSD. Decreased regional CBF in the right middle temporal gyrus, lingual gyrus, and postcentral gyrus was detected in the PTSD patients. Seed-based resting-state functional connectivity analysis was performed using an area in the right middle temporal gyrus as region of interest. Compared with the non-PTSD group, the PTSD subjects demonstrated increased functional connectivity between the right middle temporal gyrus and the right superior temporal gyrus, the left middle temporal gyrus. Meanwhile, decreased functional connectivity between the right middle temporal gyrus and the right postcentral gyrus, the right superior parietal lobule was also found in the PTSD patients. This is the first study which investigated resting-state functional connectivity in PTSD using ASL images. The results may provide new insight into the neural substrates of PTSD.

  17. Increased cortical capillary transit time heterogeneity in Alzheimer's disease: a DSC-MRI perfusion study.

    PubMed

    Eskildsen, Simon F; Gyldensted, Louise; Nagenthiraja, Kartheeban; Nielsen, Rune B; Hansen, Mikkel Bo; Dalby, Rikke B; Frandsen, Jesper; Rodell, Anders; Gyldensted, Carsten; Jespersen, Sune N; Lund, Torben E; Mouridsen, Kim; Brændgaard, Hans; Østergaard, Leif

    2017-02-01

    Alzheimer's disease (AD) is characterized by the accumulation of hyperphosphorylated tau and neurotoxic Aβ in the brain parenchyma. Hypoxia caused by microvascular changes and disturbed capillary flows could stimulate this build-up of AD-specific proteins in the brain. In this study, we compared cerebral microcirculation in a cohort of AD and mild cognitive impairment (MCI) patients with that of age-matched controls, all without a history of diabetes or of hypertension for more than 2 years, using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI). Vascular flow disturbances were quantified using a parametric model and mapped to the mid-cortical surface for group-wise statistical analysis. We found widespread hypoperfusion in patients compared with controls and identified areas of increased relative capillary transit time heterogeneity (RTH), consistent with low tissue oxygen tension. Notably, RTH was positively correlated with white matter hyperintensities and positively correlated with symptom severity in the patient cohort. These correlations extended over large parts of the temporal, parietal, and frontal cortices. The results support the hypothesis of disturbed capillary flow patterns in AD and suggest that DSC-MRI may provide imaging biomarkers of impaired cerebral microcirculation in AD.

  18. Structural and Perfusion Abnormalities of Brain on MRI and Technetium-99m-ECD SPECT in Children With Cerebral Palsy: A Comparative Study.

    PubMed

    Rana, Kamer Singh; Narwal, Varun; Chauhan, Lokesh; Singh, Giriraj; Sharma, Monica; Chauhan, Suneel

    2016-04-01

    Cerebral palsy has traditionally been associated with hypoxic ischemic brain damage. This study was undertaken to demonstrate structural and perfusion brain abnormalities. Fifty-six children diagnosed clinically as having cerebral palsy were studied between 1 to 14 years of age and were subjected to 3 Tesla magnetic resonance imaging (MRI). Brain and Technetium-99m-ECD brain single-photon emission computed tomography (SPECT) scan. Male to female ratio was 1.8:1 with a mean age of 4.16 ± 2.274 years. Spastic cerebral palsy was the most common type, observed in 91%. Birth asphyxia was the most common etiology (69.6%). White matter changes (73.2%) such as periventricular leukomalacia and corpus callosal thinning were the most common findings on MRI. On SPECT all cases except one revealed perfusion impairments in different regions of brain. MRI is more sensitive in detecting white matter changes, whereas SPECT is better in detecting cortical and subcortical gray matter abnormalities of perfusion.

  19. Non-local means variants for denoising of diffusion-weighted and diffusion tensor MRI.

    PubMed

    Wiest-Daesslé, Nicolas; Prima, Sylvain; Coupé, Pierrick; Morrissey, Sean Patrick; Barillot, Christian

    2007-01-01

    Diffusion tensor imaging (DT-MRI) is very sensitive to corrupting noise due to the non linear relationship between the diffusion-weighted image intensities (DW-MRI) and the resulting diffusion tensor. Denoising is a crucial step to increase the quality of the estimated tensor field. This enhanced quality allows for a better quantification and a better image interpretation. The methods proposed in this paper are based on the Non-Local (NL) means algorithm. This approach uses the natural redundancy of information in images to remove the noise. We introduce three variations of the NL-means algorithms adapted to DW-MRI and to DT-MRI. Experiments were carried out on a set of 12 diffusion-weighted images (DW-MRI) of the same subject. The results show that the intensity based NL-means approaches give better results in the context of DT-MRI than other classical denoising methods, such as Gaussian Smoothing, Anisotropic Diffusion and Total Variation.

  20. DCE-MRI of hepatocellular carcinoma: perfusion quantification with Tofts model versus shutter-speed model—initial experience

    PubMed Central

    Jajamovich, Guido H.; Huang, Wei; Besa, Cecilia; Li, Xin; Afzal, Aneela; Dyvorne, Hadrien A.; Taouli, Bachir

    2016-01-01

    Objective To quantify hepatocellular carcinoma (HCC) perfusion and flow with the fast exchange regime-allowed Shutter-Speed model (SSM) compared to the Tofts model (TM). Materials and methods In this prospective study, 25 patients with HCC underwent DCE-MRI. ROIs were placed in liver parenchyma, portal vein, aorta and HCC lesions. Signal intensities were analyzed employing dual-input TM and SSM models. ART (arterial fraction), Ktrans (contrast agent transfer rate constant from plasma to extravascular extracellular space), ve (extravascular extracellular volume fraction), kep (contrast agent intravasation rate constant), and τi (mean intracellular water molecule lifetime) were compared between liver parenchyma and HCC, and ART, Ktrans, ve and kep were compared between models using Wilcoxon tests and limits of agreement. Test–retest reproducibility was assessed in 10 patients. Results ART and ve obtained with TM; ART, ve, ke and τi obtained with SSM were significantly different between liver parenchyma and HCC (p < 0.04). Parameters showed variable reproducibility (CV range 14.7–66.5 % for both models). Liver Ktrans and ve; HCC ve and kep were significantly different when estimated with the two models (p < 0.03). Conclusion Our results show differences when computed between the TM and the SSM. However, these differences are smaller than parameter reproducibilities and may be of limited clinical significance. PMID:26646522

  1. Current concepts on magnetic resonance imaging (MRI) perfusion-diffusion assessment in acute ischaemic stroke: a review & an update for the clinicians

    PubMed Central

    Roldan-Valadez, Ernesto; Lopez-Mejia, Mariana

    2014-01-01

    Recently, several medical societies published joint statements about imaging recommendations for acute stroke and transient ischaemic attack patients. In following with these published guidelines, we considered it appropriate to present a brief, practical and updated review of the most relevant concepts on the MRI assessment of acute stroke. Basic principles of the clinical interpretation of diffusion, perfusion, and MRI angiography (as part of a global MRI protocol) are discussed with accompanying images for each sequence. Brief comments on incidence and differential diagnosis are also included, together with limitations of the techniques and levels of evidence. The purpose of this article is to present knowledge that can be applied in day-to-day clinical practice in specialized stroke units or emergency rooms to attend patients with acute ischaemic stroke or transient ischaemic attack according to international standards. PMID:25758570

  2. Reproducibility of BOLD, Perfusion, and CMRO2 Measurements with Calibrated-BOLD fMRI

    PubMed Central

    Leontiev, Oleg; Buxton, Richard B.

    2007-01-01

    The coupling of changes in cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) during brain activation can be characterized by an empirical index, n, defined as the ratio between fractional CBF change and fractional CMRO2 change. The combination of blood oxygenation level dependent (BOLD) imaging with CBF measurements from arterial spin labeling (ASL) provides a potentially powerful experimental approach for measuring n, but the reproducibility of the technique previously has not been assessed. In this study, inter-subject variance and intra-subject reproducibility of the method were determined. Block design %BOLD and %CBF responses to visual stimulation and mild hypercapnia (5% CO2) were measured, and these data were used to compute the BOLD scaling factor M, %CMRO2 change with activation, and the coupling index n. Reproducibility was determined for three approaches to defining regions-of-interest (ROIs): 1) Visual area V1 determined from prior retinotopic maps, 2) BOLD-activated voxels from a separate functional localizer, and 3) CBF–activated voxels from a separate functional localizer. For estimates of %BOLD, %CMRO2 and n, intra-subject reproducibility was found to be best for regions selected according to CBF activation. Among all fMRI measurements, estimates of n were the most robust and were substantially more stable within individual subjects (coefficient of variation, CV=7.4%) than across the subject pool (CV=36.9%). The stability of n across days, despite wider variability of CBF and CMRO2 responses, suggests that the reproducibility of blood flow changes is limited by variation in the oxidative metabolic demand. We conclude that the calibrated BOLD approach provides a highly reproducible measurement of n that can serve as a useful quantitative probe of the coupling of blood flow and energy metabolism in the brain. PMID:17208013

  3. Reproducibility of BOLD, perfusion, and CMRO2 measurements with calibrated-BOLD fMRI.

    PubMed

    Leontiev, Oleg; Buxton, Richard B

    2007-03-01

    The coupling of changes in cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO(2)) during brain activation can be characterized by an empirical index, n, defined as the ratio between fractional CBF change and fractional CMRO(2) change. The combination of blood oxygenation level dependent (BOLD) imaging with CBF measurements from arterial spin labeling (ASL) provides a potentially powerful experimental approach for measuring n, but the reproducibility of the technique previously has not been assessed. In this study, inter-subject variance and intra-subject reproducibility of the method were determined. Block design %BOLD and %CBF responses to visual stimulation and mild hypercapnia (5% CO(2)) were measured, and these data were used to compute the BOLD scaling factor M, %CMRO(2) change with activation, and the coupling index n. Reproducibility was determined for three approaches to defining regions-of-interest (ROIs): 1) Visual area V1 determined from prior retinotopic maps, 2) BOLD-activated voxels from a separate functional localizer, and 3) CBF-activated voxels from a separate functional localizer. For estimates of %BOLD, %CMRO(2) and n, intra-subject reproducibility was found to be best for regions selected according to CBF activation. Among all fMRI measurements, estimates of n were the most robust and were substantially more stable within individual subjects (coefficient of variation, CV=7.4%) than across the subject pool (CV=36.9%). The stability of n across days, despite wider variability of CBF and CMRO(2) responses, suggests that the reproducibility of blood flow changes is limited by variation in the oxidative metabolic demand. We conclude that the calibrated BOLD approach provides a highly reproducible measurement of n that can serve as a useful quantitative probe of the coupling of blood flow and energy metabolism in the brain.

  4. Postischemic hyperperfusion on arterial spin labeled perfusion MRI is linked to hemorrhagic transformation in stroke

    PubMed Central

    Yu, Songlin; Liebeskind, David S; Dua, Sumit; Wilhalme, Holly; Elashoff, David; Qiao, Xin J; Alger, Jeffry R; Sanossian, Nerses; Starkman, Sidney; Ali, Latisha K; Scalzo, Fabien; Lou, Xin; Yoo, Bryan; Saver, Jeffrey L; Salamon, Noriko; Wang, Danny JJ

    2015-01-01

    The purpose of this study was to investigate the relationship between hyperperfusion and hemorrhagic transformation (HT) in acute ischemic stroke (AIS). Pseudo-continuous arterial spin labeling (ASL) with background suppressed 3D GRASE was performed during routine clinical magnetic resonance imaging (MRI) on AIS patients at various time points. Arterial spin labeling cerebral blood flow (CBF) maps were visually inspected for the presence of hyperperfusion. Hemorrhagic transformation was followed during hospitalization and was graded on gradient recalled echo (GRE) scans into hemorrhagic infarction (HI) and parenchymal hematoma (PH). A total of 361 ASL scans were collected from 221 consecutive patients with middle cerebral artery stroke from May 2010 to September 2013. Hyperperfusion was more frequently detected posttreatment (odds ratio (OR)=4.8, 95% confidence interval (CI) 2.5 to 8.9, P<0.001) and with high National Institutes of Health Stroke Scale (NIHSS) scores at admission (P<0.001). There was a significant association between having hyperperfusion at any time point and HT (OR=3.5, 95% CI 2.0 to 6.3, P<0.001). There was a positive relationship between the grade of HT and time–hyperperfusion with the Spearman's rank correlation of 0.44 (P=0.003). Arterial spin labeling hyperperfusion may provide an imaging marker of HT, which may guide the management of AIS patients post tissue-type plasminogen activator (tPA) and/or endovascular treatments. Late hyperperfusion should be given more attention to prevent high-grade HT. PMID:25564233

  5. Diffusion Weighted MRI by Spatiotemporal Encoding: Analytical Description and In Vivo Validations

    PubMed Central

    Solomon, Eddy; Shemesh, Noam; Frydman, Lucio

    2016-01-01

    Diffusion-Weighted (DW) MRI is a powerful modality for studying microstructure in normal and pathological tissues. DW MRI, however, is of limited use in regions suffering from large magnetic field or chemical shift heterogeneities. Spatio-temporal encoding (SPEN) is a single-scan imaging technique that can deliver its information with a remarkable insensitivity to field inhomogeneities; this study explores the use of diffusion-weighted SPEN (dSPEN) MRI as an alternative for acquiring this kind of information. Owing to SPEN’s combined use of gradients and radiofrequency-swept pulses, spatially-dependent diffusion weightings arise in these sequences that are not present in conventional k-space DW MRI. In order to account for these phenomena an analytical formalism is presented that extends Stejskal & Tanner’s and Karlicek & Lowe’s work, to derive the b-values arising upon taking into account the effects of adiabatic pulses, of imaging as well as diffusion gradients, and of cross-terms between them. Excellent agreement is found between the new features predicted by these analytical and numerical derivations, and SPEN diffusion experiments in phantoms and in anisotropic ex vivo systems. Examinations of apparent diffusion coefficients in human breast volunteers also verify the advantages of the new methods in vivo, which exhibit substantial robustness vis-à-vis comparable DW echo planar imaging. PMID:23562003

  6. Gd-doped BNNTs as T2-weighted MRI contrast agents

    NASA Astrophysics Data System (ADS)

    Ciofani, Gianni; Boni, Adriano; Calucci, Lucia; Forte, Claudia; Gozzi, Alessandro; Mazzolai, Barbara; Mattoli, Virgilio

    2013-08-01

    This work describes, for the first time, doping of boron nitride nanotubes (BNNTs) with gadolinium (Gd@BNNTs), a stable functionalization that permits non-invasive BNNT tracking via magnetic resonance imaging (MRI). We report the structure, Gd loading, and relaxometric properties in water suspension at 7 T of Gd@BNNTs, and show the behaviour of these nanostructures as promising T2-weighted contrast agents. Finally, we demonstrate their complete biocompatibility in vitro on human neuroblastoma cells, together with their ability to effectively label and affect contrast in MRI images at 7 T.

  7. Focal and Generalized Patterns of Cerebral Cortical Veins Due to Non-Convulsive Status Epilepticus or Prolonged Seizure Episode after Convulsive Status Epilepticus – A MRI Study Using Susceptibility Weighted Imaging

    PubMed Central

    Verma, Rajeev Kumar; Abela, Eugenio; Schindler, Kaspar; Krestel, Heinz; Springer, Elisabeth; Huber, Adrian; Weisstanner, Christian; Hauf, Martinus; Gralla, Jan; Wiest, Roland

    2016-01-01

    Objective The aim of this study was to investigate variant patterns of cortical venous oxygenation during status epilepticus (SE) using susceptibility-weighted imaging (SWI). Methods We analyzed magnetic resonance imaging (MRI) scans of 26 patients with clinically witnessed prolonged seizures and/or EEG-confirmed SE. All MRI exams encompassed SWI, dynamic susceptibility contrast perfusion MRI (MRI-DSC) and diffusion-weighted imaging (DWI). We aimed to identify distinct patterns of SWI signal alterations that revealed regional or global increases of cerebral blood flow (CBF) and DWI restrictions. We hypothesized that SWI-related oxygenation patterns reflect ictal or postictal patterns that resemble SE or sequelae of seizures. Results Sixteen patients were examined during nonconvulsive status epilepticus (NCSE) as confirmed by EEG, a further ten patients suffered from witnessed and prolonged seizure episode ahead of imaging without initial EEG. MRI patterns of 15 of the 26 patients revealed generalized hyperoxygenation by SWI in keeping with either global or multifocal cortical hyperperfusion. Eight patients revealed a focal hyperoxygenation pattern related to focal CBF increase and three patients showed a focal deoxygenation pattern related to focal CBF decrease. Conclusions SWI-related hyper- and deoxygenation patterns resemble ictal and postictal CBF changes within a range from globally increased to focally decreased perfusion. In all 26 patients the SWI patterns were in keeping with ictal hyperperfusion (hyperoxygenation patterns) or postictal hypoperfusion (deoxygenation patterns) respectively. A new finding of this study is that cortical venous patterns in SWI can be not only focally, but globally attenuated. SWI may thus be considered as an alternative contrast-free MR sequence to identify perfusion changes related to ictal or postictal conditions. PMID:27486662

  8. Methanol-induced toxic optic neuropathy with diffusion weighted MRI findings.

    PubMed

    Tanrivermis Sayit, Asli; Aslan, Kerim; Elmali, Muzaffer; Gungor, Inci

    2016-12-01

    We report a 52-year-old man with methanol intoxication who showed optic nerve damage as assessed by magnetic resonance imaging (MRI). He was admitted to the hospital with blurred vision after the consumption of alcohol (600-700 ml of cologne). He was treated with intravenous ethanol, NaHCO3 and hemodialysis. On admission, a brain and orbital MRI was performed. Bilateral mild contrast enhancement was detected on the contrast-enhanced images in the retrobulbar segment of the optic nerves (RBONs). Also, diffusion-weighted images showed restricted diffusion in the RBONs. Diagnosis was considered as methanol-induced optic neuropathy based on the MRI findings of the optic nerves.

  9. FAIR exempting separate T (1) measurement (FAIREST): a novel technique for online quantitative perfusion imaging and multi-contrast fMRI.

    PubMed

    Lai, S; Wang, J; Jahng, G H

    2001-01-01

    A new pulse sequence, dubbed FAIR exempting separate T(1) measurement (FAIREST) in which a slice-selective saturation recovery acquisition is added in addition to the standard FAIR (flow-sensitive alternating inversion recovery) scheme, was developed for quantitative perfusion imaging and multi-contrast fMRI. The technique allows for clean separation between and thus simultaneous assessment of BOLD and perfusion effects, whereas quantitative cerebral blood flow (CBF) and tissue T(1) values are monitored online. Online CBF maps were obtained using the FAIREST technique and the measured CBF values were consistent with the off-line CBF maps obtained from using the FAIR technique in combination with a separate sequence for T(1) measurement. Finger tapping activation studies were carried out to demonstrate the applicability of the FAIREST technique in a typical fMRI setting for multi-contrast fMRI. The relative CBF and BOLD changes induced by finger-tapping were 75.1 +/- 18.3 and 1.8 +/- 0.4%, respectively, and the relative oxygen consumption rate change was 2.5 +/- 7.7%. The results from correlation of the T(1) maps with the activation images on a pixel-by-pixel basis show that the mean T(1) value of the CBF activation pixels is close to the T(1) of gray matter while the mean T(1) value of the BOLD activation pixels is close to the T(1) range of blood and cerebrospinal fluid.

  10. Fast and Quantitative T1ρ-weighted Dynamic Glucose Enhanced MRI

    PubMed Central

    Schuenke, Patrick; Paech, Daniel; Koehler, Christina; Windschuh, Johannes; Bachert, Peter; Ladd, Mark E.; Schlemmer, Heinz-Peter; Radbruch, Alexander; Zaiss, Moritz

    2017-01-01

    Common medical imaging techniques usually employ contrast agents that are chemically labeled, e.g. with radioisotopes in the case of PET, iodine in the case of CT or paramagnetic metals in the case of MRI to visualize the heterogeneity of the tumor microenvironment. Recently, it was shown that natural unlabeled D-glucose can be used as a nontoxic biodegradable contrast agent in Chemical Exchange sensitive Spin-Lock (CESL) magnetic resonance imaging (MRI) to detect the glucose uptake and potentially the metabolism of tumors. As an important step to fulfill the clinical needs for practicability, reproducibility and imaging speed we present here a robust and quantitative T1ρ-weighted technique for dynamic glucose enhanced MRI (DGE-MRI) with a temporal resolution of less than 7 seconds. Applied to a brain tumor patient, the new technique provided a distinct DGE contrast between tumor and healthy brain tissue and showed the detailed dynamics of the glucose enhancement after intravenous injection. Development of this fast and quantitative DGE-MRI technique allows for a more detailed analysis of DGE correlations in the future and potentially enables non-invasive diagnosis, staging and monitoring of tumor response to therapy. PMID:28169369

  11. 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

  12. Realistic microwave breast models through T1-weighted 3-D MRI data.

    PubMed

    Tunçay, Ahmet Hakan; Akduman, Ibrahim

    2015-02-01

    In this paper we present an effective method for developing realistic numerical three-dimensional (3-D) microwave breast models of different shape, size, and tissue density. These models are especially convenient for microwave breast cancer imaging applications and numerical analysis of human breast-microwave interactions. As in the recent studies on this area, anatomical information of the breast tissue is collected from T1-weighted 3-D MRI data of different patients' in prone position. The method presented in this paper offers significant improvements including efficient noise reduction and tissue segmentation, nonlinear mapping of electromagnetic properties, realistically asymmetric phantom shape, and a realistic classification of breast phantoms. Our method contains a five-step approach where each MRI voxel is classified and mapped to the appropriate dielectric properties. In the first step, the MRI data are denoised by estimating and removing the bias field from each slice, after which the voxels are segmented into two main tissues as fibro-glandular and adipose. Using the distribution of the voxel intensities in MRI histogram, two nonlinear mapping functions are generated for dielectric permittivity and conductivity profiles, which allow each MRI voxel to map to its proper dielectric properties. Obtained dielectric profiles are then converted into 3-D numerical breast phantoms using several image processing techniques, including morphologic operations, filtering. Resultant phantoms are classified according to their adipose content, which is a critical parameter that affects penetration depth during microwave breast imaging.

  13. Motion Compensated Abdominal Diffusion Weighted MRI by Simultaneous Image Registration and Model Estimation (SIR-ME).

    PubMed

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

    2015-01-01

    Non-invasive characterization of water molecule's mobility variations by quantitative analysis of diffusion-weighted MRI (DW-MRI) signal decay in the abdomen has the potential to serve as a biomarker in gastrointestinal and oncological applications. Accurate and reproducible estimation of the signal decay model parameters is challenging due to the presence of respiratory, cardiac, and peristalsis motion. Independent registration of each b-value image to the b-value=0 s/mm(2) image prior to parameter estimation might be sub-optimal because of the low SNR and contrast difference between images of varying b-value. In this work, we introduce a motion-compensated parameter estimation framework that simultaneously solves image registration and model estimation (SIR-ME) problems by utilizing the interdependence of acquired volumes along the diffusion weighting dimension. We evaluated the improvement in model parameters estimation accuracy using 16 in-vivo DW-MRI data sets of Crohn's disease patients by comparing parameter estimates obtained using the SIR-ME model to the parameter estimates obtained by fitting the signal decay model to the acquired DW-MRI images. The proposed SIR-ME model reduced the average root-mean-square error between the observed signal and the fitted model by more than 50%. Moreover, the SIR-ME model estimates discriminate between normal and abnormal bowel loops better than the standard parameter estimates.

  14. Chemotherapy response evaluation in a mouse model of gastric cancer using intravoxel incoherent motion diffusion-weighted MRI and histopathology

    PubMed Central

    Cheng, Jin; Wang, Yi; Zhang, Chun-Fang; Wang, He; Wu, Wei-Zhen; Pan, Feng; Hong, Nan; Deng, Jie

    2017-01-01

    AIM To determine the role of intravoxel incoherent motion (IVIM) diffusion-weighted (DW) magnetic resonance imaging (MRI) using a bi-exponential model in chemotherapy response evaluation in a gastric cancer mouse model. METHODS Mice bearing MKN-45 human gastric adenocarcinoma xenografts were divided into four treated groups (TG1, 2, 3 and 4, n = 5 in each group) which received Fluorouracil and Calcium Folinate and a control group (CG, n = 7). DW-MRI scans with 14 b-values (0-1500 s/mm2) were performed before and after treatment on days 3, 7, 14 and 21. Fast diffusion component (presumably pseudo-perfusion) parameters including the fast diffusion coefficient (D*) and fraction volume (fp), slow diffusion coefficient (D) and the conventional apparent diffusion coefficients (ADC) were calculated by fitting the IVIM model to the measured DW signals. The median changes from the baseline to each post-treatment time point for each measurement (ΔADC, ΔD* and Δfp) were calculated. The differences in the median changes between the two groups were compared using the mixed linear regression model by the restricted maximum likelihood method shown as z values. Histopathological analyses including Ki-67, CD31, TUNEL and H&E were conducted in conjunction with the MRI scans. The median percentage changes were compared with the histopathological analyses between the pre- and post-treatment for each measurement. RESULTS Compared with the control group, D* in the treated group decreased significantly (ΔD*treated% = -30%, -34% and -20%, with z = -5.40, -4.18 and -1.95. P = 0.0001, 0.0001 and 0.0244) and fp increased significantly (Δfptreated% = 93%, 113% and 181%, with z = 4.63, 5.52, and 2.12, P = 0.001, 0.0001 and 0.0336) on day 3, 7 and 14, respectively. Increases in ADC in the treated group were higher than those in the control group on days 3 and 14 (z = 2.44 and 2.40, P = 0.0147 and P = 0.0164). CONCLUSION Fast diffusion measurements derived from the bi-exponential IVIM model

  15. The role of diffusion and perfusion weighted imaging in the differential diagnosis of cerebral tumors: a review and future perspectives

    PubMed Central

    2014-01-01

    The role of conventional Magnetic Resonance Imaging (MRI) in the detection of cerebral tumors has been well established. However its excellent soft tissue visualization and variety of imaging sequences are in many cases non-specific for the assessment of brain tumor grading. Hence, advanced MRI techniques, like Diffusion-Weighted Imaging (DWI), Diffusion Tensor Imaging (DTI) and Dynamic-Susceptibility Contrast Imaging (DSCI), which are based on different contrast principles, have been used in the clinical routine to improve diagnostic accuracy. The variety of quantitative information derived from these techniques provides significant structural and functional information in a cellular level, highlighting aspects of the underlying brain pathophysiology. The present work, reviews physical principles and recent results obtained using DWI/DTI and DSCI, in tumor characterization and grading of the most common cerebral neoplasms, and discusses how the available MR quantitative data can be utilized through advanced methods of analysis, in order to optimize clinical decision making. PMID:25609475

  16. Determining Functional Connectivity using fMRI Data with Diffusion-Based Anatomical Weighting

    PubMed Central

    Bowman, F. DuBois; Zhang, Lijun; Derado, Gordana; Chen, Shuo

    2012-01-01

    There is strong interest in investigating both functional connectivity (FC) using functional magnetic resonance imaging (fMRI) and structural connectivity (SC) using diffusion tensor imaging (DTI). There is also emerging evidence of correspondence between functional and structural pathways within many networks (Skudlarski et al., 2008; van den Heuvel et al., 2009; Greicius, et al., 2009), although some regions without SC exhibit strong FC (Honey et al., 2009). These findings suggest that FC may be mediated by (direct or indirect) anatomical connections, offering an opportunity to supplement fMRI data with DTI data when determining FC. We develop a novel statistical method for determining FC, called anatomically-weighted FC (awFC), which combines fMRI and DTI data. Our awFC approach implements a hierarchical clustering algorithm that establishes neural processing networks using a new distance measure consisting of two components, a primary functional component that captures correlations between fMRI signals from different regions and a secondary anatomical weight reflecting probabilities of SC. The awFC approach defaults to conventional unweighted clustering for specific parameter settings. We optimize awFC parameters using a strictly functional criterion, therefore our approach will generally perform at least as well as an unweighted analysis, with respect to intracluster coherence or autocorrelation. AwFC also yields more informative results since it provides structural properties associated with identified functional networks. We apply awFC to two fMRI data sets: resting-state data from 6 healthy subjects and data from 17 subjects performing an auditory task. In these examples, awFC leads to more highly autocorrelated networks than a conventional analysis. We also conduct a simulation study, which demonstrates accurate performance of awFC and confirms that awFC generally yields comparable, if not superior, accuracy relative to a standard approach. PMID:22634220

  17. PCLR: Phase-Constrained Low-Rank Model for Compressive Diffusion-Weighted MRI

    PubMed Central

    Zhang, Kai; Zhou, Weifeng; Hu, Xiaoping

    2015-01-01

    Purpose This work develops a compressive sensing approach for diffusion-weighted (DW) MRI. Methods A phase-constrained low-rank (PCLR) approach was developed using the image coherence across the DW directions for efficient compressive DW MRI, while accounting for drastic phase changes across the DW directions, possibly as a result of eddy current, and rigid and non-rigid motions. In PCLR, a low-resolution phase estimation was used for removing phase inconsistency between DW directions. In our implementation, GRAPPA was incorporated for better phase estimation while allowing higher undersampling factor. An efficient and easy-to-implement image reconstruction algorithm, consisting mainly of partial Fourier update and singular value decomposition, was developed for solving PCLR. Results The error measures based on diffusion-tensor-derived metrics and tractography indicated that PCLR, with its joint reconstruction of all DW images using the image coherence, outperformed the frame-independent reconstruction through zero-padding FFT. Furthermore, using GRAPPA for phase estimation, PCLR readily achieved a 4-fold undersampling. Conclusion The PCLR is developed and demonstrated for compressive DW MRI. A 4-fold reduction in k-space sampling could be readily achieved without substantial degradation of reconstructed images and diffusion tensor measures, making it possible to significantly reduce the data acquisition in DW MRI and/or improve spatial and angular resolutions. PMID:24327553

  18. 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.

  19. Perfusion patterns in postictal 99mTc-HMPAO SPECT after coregistration with MRI in patients with mesial temporal lobe epilepsy

    PubMed Central

    Hogan, R; Cook, M.; Binns, D.; Desmond, P.; Kilpatrick, C.; Murrie, V.; Morris, K.

    1997-01-01

    OBJECTIVES—To assess patterns of postictal cerebral blood flow in the mesial temporal lobe by coregistration of postictal 99mTc-HMPAO SPECT with MRI in patients with confirmed mesial temporal lobe epilepsy.
METHODS—Ten postictal and interictal 99mTc-HMPAO SPECT scans were coregistered with MRI in 10 patients with confirmed mesial temporal lobe epilepsy. Volumetric tracings of the hippocampus and amygdala from the MRI were superimposed on the postictal and interictal SPECT. Asymmetries in hippocampal and amygdala SPECT signal were then calculated using the equation:
 % Asymmetry =100 × (right − left) / (right + left)/2.
RESULTS—In the postictal studies, quantitative measurements of amygdala SPECT intensities were greatest on the side of seizure onset in all cases, with an average % asymmetry of 11.1, range 5.2-21.9.Hippocampal intensities were greatest on the side of seizure onset in six studies, with an average % asymmetry of 9.6, range 4.7-12.0.In four scans the hippocampal intensities were less on the side of seizure onset, with an average % asymmetry of 10.2, range 5.7-15.5.There was no localising quantitative pattern in interictal studies.
CONCLUSIONS—Postictal SPECT shows distinctive perfusion patterns when coregistered with MRI, which assist in lateralisation of temporal lobe seizures. Hyperperfusion in the region of the amygdala is more consistently lateralising than hyperperfusion in the region of the hippocampus in postictal studies.

 PMID:9285464

  20. 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

  1. Organic Nitrate Maintains Bone Marrow Blood Perfusion in Ovariectomized Female Rats: A Dynamic, Contrast-Enhanced Magnetic Resonance Imaging (MRI) Study

    PubMed Central

    Wang, Yi-Xiang J.; Ko, Chun Hay; Griffith, James F.; Deng, Min; Wong, Hing Lok; Gu, Tao; Huang, Yu

    2012-01-01

    This study investigated the effects of nitrate on bone mineral density (BMD) and bone marrow perfusion in ovariectomized (OVX) female rats, and also the effects of nitrate on in vitro osteoblastic activity and osteoclastic differentiation of murine monocyte/macrophage RAW 264.7 cells. Female Sprague–Dawley rats were divided into OVX + nitrate group (isosorbide-5-mononitrate, ISM, 150 mg/kg/ day b.i.d), OVX + vehicle group, and control group. Lumbar spine CT bone densitometry and perfusion MRI were performed on the rats at baseline and week 8 post-OVX. The OVX rats’ BMD decreased by 22.5% ± 5.7% at week 8 (p < 0.001); while the OVX + ISM rats’ BMD decreased by 13.1% ± 2.7% (p < 0.001). The BMD loss difference between the two groups of rats was significant (p = 0.018). The OVX rats’ lumbar vertebral perfusion MRI maximum enhancement (Emax) decreased by 10.3% ± 5.0% at week 8 (p < 0.005), while in OVX + ISM rats, the Emax increased by 5.5% ± 6.9% (p > 0.05). The proliferation of osteoblast-like UMR-106 cells increased significantly with ISM treatment at 0.78 µM to 50 μM. Treatment of UMR-106 cells with ISM also stimulated the BrdU uptake. After the RAW 264.7 cells were co-treated with osteoclastogenesis inducer RANKL and 6.25 μM ~ 100 μM of ISM for 3 days, a trend of dose-dependent increase of osteoclast number was noted. PMID:24300395

  2. Recommended implementation of arterial spin-labeled perfusion MRI for clinical applications: A consensus of the ISMRM perfusion study group and the European consortium for ASL in dementia.

    PubMed

    Alsop, David C; Detre, John A; Golay, Xavier; Günther, Matthias; Hendrikse, Jeroen; Hernandez-Garcia, Luis; Lu, Hanzhang; MacIntosh, Bradley J; Parkes, Laura M; Smits, Marion; van Osch, Matthias J P; Wang, Danny J J; Wong, Eric C; Zaharchuk, Greg

    2015-01-01

    This review provides a summary statement of recommended implementations of arterial spin labeling (ASL) for clinical applications. It is a consensus of the ISMRM Perfusion Study Group and the European ASL in Dementia consortium, both of whom met to reach this consensus in October 2012 in Amsterdam. Although ASL continues to undergo rapid technical development, we believe that current ASL methods are robust and ready to provide useful clinical information, and that a consensus statement on recommended implementations will help the clinical community to adopt a standardized approach. In this review, we describe the major considerations and trade-offs in implementing an ASL protocol and provide specific recommendations for a standard approach. Our conclusion is that as an optimal default implementation, we recommend pseudo-continuous labeling, background suppression, a segmented three-dimensional readout without vascular crushing gradients, and calculation and presentation of both label/control difference images and cerebral blood flow in absolute units using a simplified model.

  3. A new look at the fetus: thick-slab T2-weighted sequences in fetal MRI.

    PubMed

    Brugger, Peter C; Mittermayer, Christoph; Prayer, Daniela

    2006-02-01

    Although magnetic resonance imaging (MRI) of the fetus is considered an established adjunct to fetal ultrasound, stacks of images alone cannot provide an overall impression of the fetus. The present study evaluates the use of thick-slab T2-weighted MR images to obtain a three-dimensional impression of the fetus using MRI. A thick-slab T2-weighted sequence was added to the routine protocol in 100 fetal MRIs obtained for various indications (19th to 37th gestational weeks) on a 1.5 T magnet using a five-element phased-array surface coil. Slice thickness adapted to fetal size and uterine geometry varied between 25 and 50mm, as did the field of view (250-350 mm). Acquisition of one image took less than 1s. The pictorial essay shows that these images visualize fetal anatomy in a more comprehensive way than is possible with a series of 3-4mm thick slices. These thick-slab images facilitate the assessment of the whole fetus, fetal proportions, surface structures, and extremities. Fetal pathology may be captured in one image. Thick-slab T2-weighted images provide additional information that cannot be gathered from a series of images and are considered a valuable adjunct to conventional 2D MR images.

  4. Clinical investigation survival prediction in high-grade gliomas by MRI perfusion before and during early stage of RT

    SciTech Connect

    Cao Yue . E-mail: yuecao@med.umich.edu; Tsien, Christina I.; Nagesh, Vijaya; Junck, Larry; Haken, Randall ten; Ross, Brian D.; Chenevert, Thomas L.; Lawrence, Theodore S.

    2006-03-01

    Purpose: To determine whether cerebral blood volume (CBV) and cerebral blood flow can predict the response of high-grade gliomas to radiotherapy (RT) by taking into account spatial heterogeneity and temporal changes in perfusion. Methods and Materials: Twenty-three patients with high-grade gliomas underwent conformal RT, with magnetic resonance imaging perfusion before and at Weeks 1-2 and 3-4 during RT. Tumor perfusion was classified as high, medium, or low. The prognostic values of pre-RT perfusion and the changes during RT for early prediction of tumor response to RT were evaluated. Results: The fractional high-CBV tumor volume before RT and the fluid-attenuated inversion recovery imaging tumor volume were identified as predictors for survival (p = 0.01). Changes in tumor CBV during the early treatment course also predicted for survival. Better survival was predicted by a decrease in the fractional low-CBV tumor volume at Week 1 of RT vs. before RT, a decrease in the fractional high-CBV tumor volume at Week 3 vs. Week 1 of RT, and a smaller pre-RT fluid-attenuated inversion recovery imaging tumor volume (p = 0.01). Conclusion: Early temporal changes during RT in heterogeneous regions of high and low perfusion in gliomas might predict for different physiologic responses to RT. This might also open the opportunity to identify tumor subvolumes that are radioresistant and might benefit from intensified RT.

  5. Implementation and evaluation of a new workflow for registration and segmentation of pulmonary MRI data for regional lung perfusion assessment.

    PubMed

    Böttger, T; Grunewald, K; Schöbinger, M; Fink, C; Risse, F; Kauczor, H U; Meinzer, H P; Wolf, Ivo

    2007-03-07

    Recently it has been shown that regional lung perfusion can be assessed using time-resolved contrast-enhanced magnetic resonance (MR) imaging. Quantification of the perfusion images has been attempted, based on definition of small regions of interest (ROIs). Use of complete lung segmentations instead of ROIs could possibly increase quantification accuracy. Due to the low signal-to-noise ratio, automatic segmentation algorithms cannot be applied. On the other hand, manual segmentation of the lung tissue is very time consuming and can become inaccurate, as the borders of the lung to adjacent tissues are not always clearly visible. We propose a new workflow for semi-automatic segmentation of the lung from additionally acquired morphological HASTE MR images. First the lung is delineated semi-automatically in the HASTE image. Next the HASTE image is automatically registered with the perfusion images. Finally, the transformation resulting from the registration is used to align the lung segmentation from the morphological dataset with the perfusion images. We evaluated rigid, affine and locally elastic transformations, suitable optimizers and different implementations of mutual information (MI) metrics to determine the best possible registration algorithm. We located the shortcomings of the registration procedure and under which conditions automatic registration will succeed or fail. Segmentation results were evaluated using overlap and distance measures. Integration of the new workflow reduces the time needed for post-processing of the data, simplifies the perfusion quantification and reduces interobserver variability in the segmentation process. In addition, the matched morphological data set can be used to identify morphologic changes as the source for the perfusion abnormalities.

  6. 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.

  7. Whole-body MRI including diffusion-weighted MRI compared with 5-HTP PET/CT in the detection of neuroendocrine tumors

    PubMed Central

    Carlbom, Lina; Caballero-Corbalán, José; Granberg, Dan; Sörensen, Jens; Eriksson, Barbro; Ahlström, Håkan

    2017-01-01

    Aim We wanted to explore if whole-body magnetic resonance imaging (MRI) including diffusion-weighted (DW) and liver-specific contrast agent-enhanced imaging could be valuable in lesion detection of neuroendocrine tumors (NET). [11C]-5-Hydroxytryptophan positron emission tomography/computed tomography (5-HTP PET/CT) was used for comparison. Materials and methods Twenty-one patients with NET were investigated with whole-body MRI, including DW imaging (DWI) and contrast-enhanced imaging of the liver, and whole-body 5-HTP PET/CT. Seven additional patients underwent upper abdomen MRI including DWI, liver-specific contrast agent-enhanced imaging, and 5-HTP PET/CT. Results There was a patient-based concordance of 61% and a lesion-based concordance of 53% between the modalities. MRI showed good concordance with PET in detecting bone metastases but was less sensitive in detecting metastases in mediastinal lymph nodes. MRI detected more liver metastases than 5-HTP PET/CT. Conclusion Whole-body MRI with DWI did not detect all NET lesions found with whole-body 5-HTP PET/CT. Our findings indicate that MRI of the liver including liver-specific contrast agent-enhanced imaging and DWI could be a useful complement to whole-body 5-HTP PET/CT. PMID:27894208

  8. Detection of Lesions Underlying Intractable Epilepsy on T1-Weighted MRI as an Outlier Detection Problem.

    PubMed

    El Azami, Meriem; Hammers, Alexander; Jung, Julien; Costes, Nicolas; Bouet, Romain; Lartizien, Carole

    2016-01-01

    Pattern recognition methods, such as computer aided diagnosis (CAD) systems, can help clinicians in their diagnosis by marking abnormal regions in an image. We propose a machine learning system based on a one-class support vector machine (OC-SVM) classifier for the detection of abnormalities in magnetic resonance images (MRI) applied to patients with intractable epilepsy. The system learns the features associated with healthy control subjects, allowing a voxelwise assessment of the deviation of a test subject pattern from the learned patterns. While any number of various features can be chosen and learned, here we focus on two texture parameters capturing image patterns associated with epileptogenic lesions on T1-weighted brain MRI e.g. heterotopia and blurred junction between the grey and white matter. The CAD output consists of patient specific 3D maps locating clusters of suspicious voxels ranked by size and degree of deviation from control patterns. System performance was evaluated using realistic simulations of challenging detection tasks as well as clinical data of 77 healthy control subjects and of eleven patients (13 lesions). It was compared to that of a mass univariate statistical parametric mapping (SPM) single subject analysis based on the same set of features. For all simulations, OC-SVM yielded significantly higher values of the area under the ROC curve (AUC) and higher sensitivity at low false positive rate. For the clinical data, both OC-SVM and SPM successfully detected 100% of the lesions in the MRI positive cases (3/13). For the MRI negative cases (10/13), OC-SVM detected 7/10 lesions and SPM analysis detected 5/10 lesions. In all experiments, OC-SVM produced fewer false positive detections than SPM. OC-SVM may be a versatile system for unbiased lesion detection.

  9. Detection of Lesions Underlying Intractable Epilepsy on T1-Weighted MRI as an Outlier Detection Problem

    PubMed Central

    El Azami, Meriem; Hammers, Alexander; Jung, Julien; Costes, Nicolas; Bouet, Romain; Lartizien, Carole

    2016-01-01

    Pattern recognition methods, such as computer aided diagnosis (CAD) systems, can help clinicians in their diagnosis by marking abnormal regions in an image. We propose a machine learning system based on a one-class support vector machine (OC-SVM) classifier for the detection of abnormalities in magnetic resonance images (MRI) applied to patients with intractable epilepsy. The system learns the features associated with healthy control subjects, allowing a voxelwise assessment of the deviation of a test subject pattern from the learned patterns. While any number of various features can be chosen and learned, here we focus on two texture parameters capturing image patterns associated with epileptogenic lesions on T1-weighted brain MRI e.g. heterotopia and blurred junction between the grey and white matter. The CAD output consists of patient specific 3D maps locating clusters of suspicious voxels ranked by size and degree of deviation from control patterns. System performance was evaluated using realistic simulations of challenging detection tasks as well as clinical data of 77 healthy control subjects and of eleven patients (13 lesions). It was compared to that of a mass univariate statistical parametric mapping (SPM) single subject analysis based on the same set of features. For all simulations, OC-SVM yielded significantly higher values of the area under the ROC curve (AUC) and higher sensitivity at low false positive rate. For the clinical data, both OC-SVM and SPM successfully detected 100% of the lesions in the MRI positive cases (3/13). For the MRI negative cases (10/13), OC-SVM detected 7/10 lesions and SPM analysis detected 5/10 lesions. In all experiments, OC-SVM produced fewer false positive detections than SPM. OC-SVM may be a versatile system for unbiased lesion detection. PMID:27603778

  10. Prioritizing spatial accuracy in high-resolution fMRI data using multivariate feature weight mapping

    PubMed Central

    Buschmann, Tilo; Lohmann, Gabriele; Margulies, Daniel S.; Trampel, Robert; Turner, Robert

    2014-01-01

    Although ultra-high-field fMRI at field strengths of 7T or above provides substantial gains in BOLD contrast-to-noise ratio, when very high-resolution fMRI is required such gains are inevitably reduced. The improvement in sensitivity provided by multivariate analysis techniques, as compared with univariate methods, then becomes especially welcome. Information mapping approaches are commonly used, such as the searchlight technique, which take into account the spatially distributed patterns of activation in order to predict stimulus conditions. However, the popular searchlight decoding technique, in particular, has been found to be prone to spatial inaccuracies. For instance, the spatial extent of informative areas is generally exaggerated, and their spatial configuration is distorted. We propose the combination of a non-parametric and permutation-based statistical framework with linear classifiers. We term this new combined method Feature Weight Mapping (FWM). The main goal of the proposed method is to map the specific contribution of each voxel to the classification decision while including a correction for the multiple comparisons problem. Next, we compare this new method to the searchlight approach using a simulation and ultra-high-field 7T experimental data. We found that the searchlight method led to spatial inaccuracies that are especially noticeable in high-resolution fMRI data. In contrast, FWM was more spatially precise, revealing both informative anatomical structures as well as the direction by which voxels contribute to the classification. By maximizing the spatial accuracy of ultra-high-field fMRI results, global multivariate methods provide a substantial improvement for characterizing structure-function relationships. PMID:24795548

  11. Multimodal MRI of experimental stroke

    PubMed Central

    Duong, Timothy Q

    2014-01-01

    Stroke is the fourth leading cause of death and the leading cause of long-term disability in the United States. Brain imaging data from experimental stroke models and stroke patients have shown that there is often a gradual progression of potentially reversible ischemic injury toward infarction. Reestablishing tissue perfusion and/or treating with neuroprotective drugs in a timely fashion are expected to salvage some ischemic tissues. Diffusion-weighted imaging based on magnetic resonance imaging (MRI) in which contrast is based on water motion can detect ischemic injury within minutes after onsets, whereas computed tomography and other imaging modalities fail to detect stroke injury for at least a few hours. Along with quantitative perfusion imaging, the perfusion-diffusion mismatch which approximates the ischemic penumbra could be imaged non-invasively. This review describes recent progresses in the development and application of multimodal MRI and image analysis techniques to study ischemic tissue at risk in experimental stroke in rats. PMID:24323751

  12. Arterial Spin-Labeling MRI Can Identify the Presence and Intensity of Collateral Perfusion in Patients With Moyamoya Disease

    PubMed Central

    Zaharchuk, Greg; Do, Huy M.; Marks, Michael P.; Rosenberg, Jarrett; Moseley, Michael E.; Steinberg, Gary K.

    2011-01-01

    Background and Purpose Determining the presence and adequacy of collateral blood flow is important in cerebrovascular disease. Therefore, we explored whether a noninvasive imaging modality, arterial spin labeling (ASL) MRI, could be used to detect the presence and intensity of collateral flow using digital subtraction angiography (DSA) and stable xenon CT cerebral blood flow as gold standards for collaterals and cerebral blood flow, respectively. Methods ASL and DSA were obtained within 4 days of each other in 18 patients with Moyamoya disease. Two neurointerventionalists scored DSA images using a collateral grading scale in regions of interest corresponding to ASPECTS methodology. Two neuroradiologists similarly scored ASL images based on the presence of arterial transit artifact. Agreement of ASL and DSA consensus scores was determined, including kappa statistics. In 15 patients, additional quantitative xenon CT cerebral blood flow measurements were performed and compared with collateral grades. Results The agreement between ASL and DSA consensus readings was moderate to strong, with a weighted kappa value of 0.58 (95% confidence interval, 0.52–0.64), but there was better agreement between readers for ASL compared with DSA. Sensitivity and specificity for identifying collaterals with ASL were 0.83 (95% confidence interval, 0.77–0.88) and 0.82 (95% confidence interval, 0.76–0.87), respectively. Xenon CT cerebral blood flow increased with increasing DSA and ASL collateral grade (P<0.05). Conclusions ASL can noninvasively predict the presence and intensity of collateral flow in patients with Moyamoya disease using DSA as a gold standard. Further study of other cerebrovascular diseases, including acute ischemic stroke, is warranted. PMID:21799169

  13. [Effect of vibration caused by time-varying magnetic fields on diffusion-weighted MRI].

    PubMed

    Ogura, Akio; Maeda, Fumie; Miyai, Akira; Hayashi, Kohji; Hongoh, Takaharu

    2006-04-20

    Diffusion-weighted images (DWIs) with high b-factor in the body are often used to detect and diagnose cancer at MRI. The echo planar imaging (EPI) sequence and high motion probing gradient pulse are used at diffusion weighted imaging, causing high table vibration. The purpose of this study was to assess whether the diffusion signal and apparent diffusion coefficient (ADC) values are influenced by this vibration because of time-varying magnetic fields. Two DWIs were compared. In one, phantoms were fixed on the MRI unit's table transmitting the vibration. In the other, phantoms were supported in air, in the absence of vibration. The phantoms called "solution phantoms" were made from agarose of a particular density. The phantoms called "jelly phantoms" were made from agarose that was heated. The diffusion signal and ADC value of each image were compared. The results showed that the signal of DWI units using the solution phantom was not affected by vibration. However, the signal of DWI and ADC were increased in the low-density jelly phantom as a result of vibration, causing the jelly phantom to vibrate. The DWIs of vibrating regions such as the breast maybe be subject to error. A countermeasure seems to be to support the region adequately.

  14. Computer-aided detection of prostate cancer in T2-weighted MRI within the peripheral zone

    NASA Astrophysics Data System (ADS)

    Rampun, Andrik; Zheng, Ling; Malcolm, Paul; Tiddeman, Bernie; Zwiggelaar, Reyer

    2016-07-01

    In this paper we propose a prostate cancer computer-aided diagnosis (CAD) system and suggest a set of discriminant texture descriptors extracted from T2-weighted MRI data which can be used as a good basis for a multimodality system. For this purpose, 215 texture descriptors were extracted and eleven different classifiers were employed to achieve the best possible results. The proposed method was tested based on 418 T2-weighted MR images taken from 45 patients and evaluated using 9-fold cross validation with five patients in each fold. The results demonstrated comparable results to existing CAD systems using multimodality MRI. We achieved an area under the receiver operating curve (A z ) values equal to 90.0%+/- 7.6% , 89.5%+/- 8.9% , 87.9%+/- 9.3% and 87.4%+/- 9.2% for Bayesian networks, ADTree, random forest and multilayer perceptron classifiers, respectively, while a meta-voting classifier using average probability as a combination rule achieved 92.7%+/- 7.4% .

  15. Diffusion Weighted MRI and MRS to Differentiate Radiation Necrosis and Recurrent Disease in Gliomas

    NASA Astrophysics Data System (ADS)

    Ewell, Lars

    2006-03-01

    A difficulty encountered in the diagnosis of patients with gliomas is the differentiation between recurrent disease and Radiation Induced Necrosis (RIN). Both can appear as ‘enhancing lesions’ on a typical T2 weighted MRI scan. Magnetic Resonance Spectroscopy (MRS) and Diffusion Weighted MRI (DWMRI) have the potential to be helpful regarding this differentiation. MRS has the ability to measure the concentration of brain metabolites, such as Choline, Creatin and N- Acetyl Aspartate, the ratios of which have been shown to discriminate between RIN and recurrent disease. DWMRI has been linked via a rise in the Apparent Diffusion Coefficient (ADC) to successful treatment of disease. Using both of these complimentary non-invasive imaging modalities, we intend to initiate an imaging protocol whereby we will study how best to combine metabolite ratios and ADC values to obtain the most useful information in the least amount of scan time. We will look for correlations over time between ADC values, and MRS, among different sized voxels.

  16. Comparison of TTP and Tmax estimation techniques in perfusion-weighted MR datasets for tissue-at-risk definition

    NASA Astrophysics Data System (ADS)

    Forkert, Nils Daniel; Kaesemann, Philipp; Fiehler, Jens; Thomalla, Götz

    2012-03-01

    Acute stroke is a major cause for death and disability among adults in the western hemisphere. Time-resolved perfusion-weighted (PWI) and diffusion-weighted (DWI) MR datasets are typically used for the estimation of tissue-at-risk, which is an important variable for acute stroke therapy decision-making. Although several parameters, which can be estimated based on PWI concentration curves, have been proposed for tissue-at-risk definition in the past, the time-to-peak (TTP) or time-to-max (Tmax) parameter is used most frequently in recent trials. Unfortunately, there is no clear consensus which method should be used for estimation of Tmax or TTP maps. Consequently, tissue-at-risk estimations and following treatment decision might vary considerably with the method used. In this work, 5 PWI datasets of acute stroke patients were used to calculate TTP or Tmax maps using 10 different estimation techniques. The resulting maps were segmented using a typical threshold of +4s and the corresponding PWI-lesions were calculated. The first results suggest that the TTP or Tmax method used has a major impact on the resulting tissue-at-risk volume. Numerically, the calculated volumes differed up to a factor of 3. In general, the deconvolution-based Tmax techniques estimate the ischemic penumbra rather smaller compared to direct TTP based techniques. In conclusion, the comparison of different methods for TTP or Tmax estimation revealed high variations regarding the resulting tissue-at-risk volume, which might lead to different therapy decisions. Therefore, a consensus how TTP or Tmax maps should be calculated seems necessary.

  17. Acute caffeine administration impact on working memory-related brain activation and functional connectivity in the elderly: a BOLD and perfusion MRI study.

    PubMed

    Haller, S; Rodriguez, C; Moser, D; Toma, S; Hofmeister, J; Sinanaj, I; Van De Ville, D; Giannakopoulos, P; Lovblad, K-O

    2013-10-10

    In young individuals, caffeine-mediated blockade of adenosine receptors and vasoconstriction has direct repercussions on task-related activations, changes in functional connectivity, as well as global vascular effects. To date, no study has explored the effect of caffeine on brain activation patterns during highly demanding cognitive tasks in the elderly. This prospective, placebo-controlled crossover design comprises 24 healthy elderly individuals (mean age 68.8 ± 4.0 years, 17 females) performing a 2-back working memory (WM) task in functional magnetic resonance imaging (fMRI). Analyses include complimentary assessment of task-related activations (general linear model, GLM), functional connectivity (tensorial independent component analysis, TICA), and baseline perfusion (arterial spin labeling). Despite a reduction in whole-brain global perfusion (-22.7%), caffeine-enhanced task-related GLM activation in a local and distributed network is most pronounced in the bilateral striatum and to a lesser degree in the right middle and inferior frontal gyrus, bilateral insula, left superior and inferior parietal lobule as well as in the cerebellum bilaterally. TICA was significantly enhanced (+8.2%) in caffeine versus placebo in a distributed and task-relevant network including the pre-frontal cortex, the supplementary motor area, the ventral premotor cortex and the parietal cortex as well as the occipital cortex (visual stimuli) and basal ganglia. The inverse comparison of placebo versus caffeine had no significant difference. Activation strength of the task-relevant-network component correlated with response accuracy for caffeine yet not for placebo, indicating a selective cognitive effect of caffeine. The present findings suggest that acute caffeine intake enhances WM-related brain activation as well as functional connectivity of blood oxygen level-dependent fMRI in elderly individuals.

  18. Predictive values of diffusion-weighted imaging and perfusion-weighted imaging in evaluating the efficacy of transcatheter arterial chemoembolization for hepatocellular carcinoma

    PubMed Central

    Lin, Min; Tian, Man-Man; Zhang, Wei-Ping; Xu, Li; Jin, Ping

    2016-01-01

    This study explored the predictive values of diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) in evaluating the efficacy of transcatheter arterial chemoembolization (TACE) for patients with hepatocellular carcinoma (HCC). A total of 118 HCC patients treated with TACE were selected from April 2013 to November 2015. T1-weighted imaging (T1WI)/T2-weighted imaging (T2WI), DWI, and PWI were performed on all patients before and after TACE. Efficacy was evaluated according to modified Response Evaluation Criteria in Solid Tumors 1.1. Receiver operating characteristic curve was used to evaluate the diagnostic power of quantitative DWI and PWI parameters in evaluating the efficacy of TACE for HCC patients. Among the 118 HCC patients, there were 17 cases (14.4%) with complete response, 50 cases (42.4%) with partial response, 28 cases (23.7%) with stable disease, and 23 cases (19.5%) with progressive disease. There were 67 patients in the effective group (complete response + partial response) and 51 patients in the ineffective group (stable disease + progressive disease). Before TACE, there were significant differences in maximum tumor diameter (MTD), apparent diffusion coefficient (ADC), slow ADC (Dslow), fast ADC (Dfast), transfer constant of vessel at the maximum level (Ktrans), and rate constant of backflux (Kep) between the effective and ineffective groups (all P<0.05). After TACE, the effective group exhibited lower MTD, Dfast, and Kep and higher ADC and Dslow than the ineffective group (all P<0.05). Tumor regression rate negatively correlated with MTD, Ktrans, Kep, and Dfast but positively correlated with ADC and Dslow. Receiver operating characteristic curve analysis suggested that the area under the curve of ADC, Dslow, Dfast, Ktrans, and Kep were 0.869, 0.833, 0.812, 0.802, and 0.809, respectively. In conclusion, these results suggest that quantitative DWI and PWI parameters might be useful in evaluating the efficacy of TACE in the treatment of

  19. 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

    Purpose: This work describes a spatially variant mixture model constrained by a Markov random field to model high angular resolution diffusion imaging (HARDI) data. Mixture models suit HARDI well because the attenuation by diffusion is inherently a mixture. The goal is to create a general model that can be used in different applications. This study focuses on image denoising and segmentation (primarily the former). Methods: HARDI signal attenuation data are used to train a Gaussian mixture model in which the mean vectors and covariance matrices are assumed to be independent of spatial locations, whereas the mixture weights are allowed to vary at different lattice positions. Spatial smoothness of the data is ensured by imposing a Markov random field prior on the mixture weights. The model is trained in an unsupervised fashion using the expectation maximization algorithm. The number of mixture components is determined using the minimum message length criterion from information theory. Once the model has been trained, it can be fitted to a noisy diffusion MRI volume by maximizing the posterior probability of the underlying noiseless data in a Bayesian framework, recovering a denoised version of the image. Moreover, the fitted probability maps of the mixture components can be used as features for posterior image segmentation. Results: The model-based denoising algorithm proposed here was compared on real data with three other approaches that are commonly used in the literature: Gaussian filtering, anisotropic diffusion, and Rician-adapted nonlocal means. The comparison shows that, at low signal-to-noise ratio, when these methods falter, our algorithm considerably outperforms them. When tractography is performed on the model-fitted data rather than on the noisy measurements, the quality of the output improves substantially. Finally, ventricle and caudate nucleus segmentation experiments also show the potential usefulness of the mixture probability maps for

  20. 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

  1. 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.

  2. Temporal and spatial profile of brain diffusion-weighted MRI after cardiac arrest

    PubMed Central

    Mlynash, M.; Campbell, D.M.; Leproust, E.M.; Fischbein, N.J.; Bammer, R.; Eyngorn, I.; Hsia, A.W.; Moseley, M.; Wijman, C.A.C.

    2010-01-01

    Background and Purpose Diffusion-weighted MRI (DWI) of the brain is a promising technique to help predict functional outcome in comatose survivors of cardiac arrest. We aimed to evaluate prospectively the temporal-spatial profile of brain apparent diffusion coefficient (ADC) changes in comatose survivors during the first 8 days after cardiac arrest. Methods ADC values were measured by two independent and blinded investigators in predefined brain regions in 18 good and 15 poor outcome patients with 38 brain MRIs, and compared with 14 normal controls. The same brain regions were also assessed qualitatively by two other independent and blinded investigators. Results In poor outcome patients, cortical structures, in particular the occipital and temporal lobes, and the putamen exhibited the most profound ADC reductions, which were noted as early as 1.5 days and reached nadir between 3 to 5 days after the arrest. Conversely, when compared to normal controls, good outcome patients exhibited increased diffusivity, in particular in the hippocampus, temporal and occipital lobes, and corona radiata. By the qualitative MRI readings, one or more cortical gray matter structures were read as moderately-to-severely abnormal in all poor outcome patients imaged beyond 54 hours after the arrest, but not in the three patients imaged earlier. Conclusions Brain DWI changes in comatose post-cardiac arrest survivors in the first week after the arrest are region- and time-dependent and differ between good and poor outcome patients. With the increasing use of MRI in this context, it is important to be aware of these relationships. PMID:20595666

  3. Crossed cerebellar diaschisis after stroke identified noninvasively with cerebral blood flow-weighted arterial spin labeling MRI

    PubMed Central

    Strother, Megan K.; Buckingham, Cari; Faraco, Carlos C.; Arteaga, Daniel; Lu, Pengcheng; Xu, Yaomin; Donahue, Manus J.

    2015-01-01

    Background and Purpose Crossed cerebellar diaschisis (CCD) is most commonly investigated using hemodynamic PET and SPECT imaging. However, noninvasive MRI offers advantages of improved spatial resolution, allowing hemodynamic changes to be compared directly with structural findings and without concerns related to ionizing radiation exposure. The aim of this study was to evaluate relationships between CCD identified from cerebral blood flow (CBF)-weighted arterial spin labeling (ASL) MRI with cerebrovascular reactivity (CVR)-weighted blood oxygenation level dependent (BOLD) MRI, Wallerian degeneration, clinical motor impairment, and corticospinal tract involvement. Methods Subjects (n=74) enrolled in an ongoing observational stroke trial underwent CBF-weighted ASL and hypercapnic CVR-weighted BOLD MRI. Hemispheric asymmetry indices for basal cerebellar CBF, cerebellar CVR, and cerebral peduncular area were compared between subjects with unilateral supratentorial infarcts (n=18) and control subjects without infarcts (n=16). CCD required (1) supratentorial infarct and (2) asymmetric cerebellar CBF (>95% confidence interval relative to controls). Results In CCD subjects (n=9), CVR (p=0.04) and cerebral peduncular area (p < 0.01) were significantly asymmetric compared to controls. Compared to infarct subjects not meeting CCD criteria (n=9), CCD subjects had no difference in corticospinal tract location for infarct (p=1.0) or motor impairment (p=0.08). Conclusions CCD correlated with cerebellar CVR asymmetry and Wallerian degeneration. These findings suggest that noninvasive MRI may be a useful alternative to PET or SPECT to study structural correlates and clinical consequences of CCD following supratentorial stroke. PMID:26724658

  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. Susceptibility-weighted MRI of extrapyramidal brain structures in Parkinsonian disorders

    PubMed Central

    Schneider, Eva; Ng, Kia-Min; Yeoh, Chooi-Sum; Rumpel, Helmut; Fook-Chong, Stephanie; Li, Hui-Hua; Tan, Eng-King; Chan, Ling-Ling

    2016-01-01

    Abstract Susceptibility-weighted MRI (SWI) is sensitive to T2∗ effects and mineralization. We investigated differences in the extrapyramidal brain structures on SWI between Parkinson disease (PD) and postural instability gait disorder (PIGD) patients and correlated the SWI values with the degree of gait dysfunction. Forty patients diagnosed with PD and PIGD underwent 3 Tesla magnetic resonance imaging (MRI) brain study. An SWI sequence (TE/TR/FA 20/33/15) was used. Ten regions of interest were placed in the midbrain and basal ganglia by 2 independent raters blinded to subject data and quantitatively evaluated. The inter-rater reliability between the raters was excellent (interclass correlation coefficient >0.8). The SWI intensity values in all regions were on average lower in PIGD than in PD patients, with the lowest results found in globus pallidus. Multivariate analysis showed a lower SWI hypointensity in the putamen and globus pallidus in PIGD compared with PD patients, with a similar trend for the other basal ganglia nuclei. Pearson correlation analysis showed a statistically significant positive correlation between SWI putaminal hypointensity and the Tinetti total score (r = 0.39, P = 0.01) in both PD and PIGD. SWI putaminal hypointensity may be a useful imaging marker in prospective evaluation for clinical progression for Parkinsonian disorders. PMID:27367979

  6. Amide proton transfer-weighted MRI detection of traumatic brain injury in rats.

    PubMed

    Zhang, Hong; Wang, Wenzhu; Jiang, Shanshan; Zhang, Yi; Heo, Hye-Young; Wang, Xianlong; Peng, Yun; Wang, Jian; Zhou, Jinyuan

    2017-01-01

    The purpose of this study was to explore the capability and uniqueness of amide proton transfer-weighted (APTw) imaging in the detection of primary and secondary injury after controlled cortical impact (CCI)-induced traumatic brain injury (TBI) in rats. Eleven adult rats had craniotomy plus CCI surgery under isoflurane anesthesia. Multi-parameter MRI data were acquired at 4.7 T, at eight time points (1, 6 h, and 1, 2, 3, 7, 14, and 28 days after TBI). At one and six hours post-injury, average APTw signal intensities decreased significantly in the impacted and peri-lesional areas due to tissue acidosis. A slightly high APTw signal was seen in the core lesion area with respect to the peri-lesional area, which was due to hemorrhage, as shown by T2*w. After the initial drop, the APTw signals dramatically increased in some peri-lesional areas at two and three days post-injury, likely due to the secondary inflammatory response. The use of APTw MRI has the potential to introduce a novel molecular neuroimaging approach for the simultaneous detection of ischemia, hemorrhage, and neuroinflammation in TBI.

  7. GRE T2∗-Weighted MRI: Principles and Clinical Applications

    PubMed Central

    Tang, Meng Yue; Chen, Tian Wu; Zhang, Xiao Ming; Huang, Xiao Hua

    2014-01-01

    The sequence of a multiecho gradient recalled echo (GRE) T2*-weighted imaging (T2*WI) is a relatively new magnetic resonance imaging (MRI) technique. In contrast to T2 relaxation, which acquires a spin echo signal, T2* relaxation acquires a gradient echo signal. The sequence of a GRE T2*WI requires high uniformity of the magnetic field. GRE T2*WI can detect the smallest changes in uniformity in the magnetic field and can improve the rate of small lesion detection. In addition, the T2* value can indirectly reflect changes in tissue biochemical components. Moreover, it can be used for the early diagnosis and quantitative diagnosis of some diseases. This paper reviews the principles and clinical applications as well as the advantages and disadvantages of GRE T2*WI. PMID:24987676

  8. Asymptomatic choroid plexus cysts in the lateral ventricles: an incidental finding on diffusion-weighted MRI.

    PubMed

    Cakir, B; Karakas, H M; Unlu, E; Tuncbilek, N

    2002-10-01

    We assessed the role of diffusion-weighted imaging (DWI) in the detection of choroid plexus cysts. We reviewed more than 1000 patients who had undergone MRI in a 1-year period. We reviewed echo-planar DWI with b=1000 s/mm(2), acquired at 1.0 tesla, for any difference in signal intensity which might indicate choroid plexus cysts. On conventional images, all cystic lesions were isointense with cerebrospinal fluid, and 72 cysts could not be identified. On DWI, 90 rounded high-signal foci were detected in 58 patients; 64 cysts were bilateral. Focal ventricular expansion due to large cysts was observed in nine cases. DWI were found to show choroid plexus cysts undetected within the cerebrospinal fluid on conventional images.

  9. Correlation of diffusion-weighted MRI with whole mount radical prostatectomy specimens.

    PubMed

    Van As, N; Charles-Edwards, E; Jackson, A; Jhavar, S; Reinsberg, S; Desouza, N; Dearnaley, D; Bailey, M; Thompson, A; Christmas, T; Fisher, C; Corbishley, C; Sohaib, S

    2008-06-01

    The purpose of this study was to compare the apparent diffusion coefficient (ADC) of benign central gland (bCG), benign peripheral zone (bPZ) and cancer using diffusion-weighted MRI and whole mount specimens. 11 patients with biopsy-proven prostate cancer underwent diffusion-weighted MRI prior to radical prostatectomy. A single-shot echo planar image technique was used with b-values of 0 s mm(-2), 300 s mm(-2), 500 s mm(-2) and 800 s mm(-2). Whole mount specimens were compared with ADC maps. Areas of cancer, bCG and bPZ were identified, and regions of interest were drawn on ADC maps. Mean ADC values were recorded for all regions of interest, and paired t-tests were performed to compare mean values. Cancer was outlined in nine patients. In two patients, the tumours were too small to correlate with images; bCG was identified in 11 patients and bPZ was identified in 10 patients. Mean ADC values for bCG, bPZ and cancer were, 1.5 x 10(-3) mm(2) s(-1) (standard error (SE) = 0.04), 1.7 x 10(-3) mm(2) s(-1) (SE = 0.1), and 1.3 x 10(-3) mm(2) s(-1) (SE = 0.09), respectively. The most significant difference between benign tissue and cancer existed at b-values of 0-300 s mm(-2) (bCG vs cancer: mean difference = 0. 29, p = 0.001, 95% confidence interval (CI) = 0.17-0.41; bPZ vs cancer: mean difference = 0.34, p = 0.003, 95% CI = 0.18-0.61). In conclusion, we have confirmed, using whole mount verification, a significant difference in the ADC between benign tissue and cancer.

  10. Evolution of Cerebral Ischemia Assessed by Amide Proton Transfer-Weighted MRI

    PubMed Central

    Song, Guodong; Li, Chunmei; Luo, Xiaojie; Zhao, Xuna; Zhang, Shuai; Zhang, Yi; Jiang, Shanshan; Wang, Xianlong; Chen, Yuhui; Chen, Haibo; Gong, Tao; Zhou, Jinyuan; Chen, Min

    2017-01-01

    Amide proton transfer-weighted (APTW) magnetic resonance imaging (MRI) has recently become a potentially important tool for evaluating acidosis in ischemic stroke. The purpose of this study was to evaluate the dynamic pH-related changes in the lesions in patients with ischemia. Thirty-nine patients with ischemic stroke (symptom onset to imaging time ranging 2 h–7 days) were examined with a 3.0-T MRI system. Patients were divided into four groups: at the hyperacute stage (onset time ≤ 6 h), at the acute stage (6 h < onset time ≤ 48 h), at the early subacute stage (48 h < onset time ≤ 96 h), and at the late subacute stage (96 h < onset time ≤ 168 h). The APTW signal intensities were quantitatively measured in multiple ischemic regions for each patient. Compared with the contralateral normal white matter, APTW signals were significantly lower in ischemic tissue for all four stages (P < 0.05). The APTW signal intensities (APTWave and APTWmin) increased consistently with onset time (R2 = 0.11, P = 0.040; R2 = 0.13, P = 0.022, respectively). APTWmax–min showed a continued reduction with onset time (R2 = 0.44, P < 0.001). Our results suggest that persistent tissue acidification could occur after ischemia, and as the time from stroke onset increases, the acidotic environment would alleviate. APTW signal intensities could reflect pH-weighted properties in ischemic tissue at different stages and time points. PMID:28303115

  11. Impairments in Brain Perfusion, Metabolites, Functional Connectivity, and Cognition in Severe Asymptomatic Carotid Stenosis Patients: An Integrated MRI Study

    PubMed Central

    Wang, Tao

    2017-01-01

    Carotid artery stenosis without transient ischemic attack (TIA) or stroke is considered as “asymptomatic.” However, recent studies have demonstrated that these asymptomatic carotid artery stenosis (aCAS) patients had cognitive impairment in tests of executive function, psychomotor speed, and memory, indicating that “asymptomatic” carotid stenosis may not be truly asymptomatic. In this study, when 19 aCAS patients compared with 24 healthy controls, aCAS patients showed significantly poorer performance on global cognition, memory, and executive function. By utilizing an integrated MRI including pulsed arterial spin labeling (pASL) MRI, Proton MR Spectroscopy (MRS), and resting-state functional MRI (R-fMRI), we also found that aCAS patients suffered decreased cerebral blood flow (CBF) mainly in the Left Frontal Gyrus and had decreased NAA/Cr ratio in the left hippocampus and decreased connectivity to the posterior cingulate cortex (PCC) in the anterior part of default mode network (DMN). PMID:28255464

  12. Nearly Automatic Segmentation of Hippocampal Subfields in In Vivo Focal T2-Weighted MRI

    PubMed Central

    Yushkevich, Paul A.; Wang, Hongzhi; Pluta, John; Das, Sandhitsu R.; Craige, Caryne; Avants, Brian B.; Weiner, Michael W.; Mueller, Susanne

    2010-01-01

    We present and evaluate a new method for automatically labeling the subfields of the hippocampal formation in focal 0.4×0.5×2.0mm3 resolution T2-weighted magnetic resonance images that can be acquired in the routine clinical setting with under 5 min scan time. The method combines multi-atlas segmentation, similarity-weighted voting, and a novel learning-based bias correction technique to achieve excellent agreement with manual segmentation. Initial partitioning of MRI slices into hippocampal ‘head’, ‘body’ and ‘tail’ slices is the only input required from the user, necessitated by the nature of the underlying segmentation protocol. Dice overlap between manual and automatic segmentation is above 0.87 for the larger subfields, CA1 and dentate gyrus, and is competitive with the best results for whole-hippocampus segmentation in the literature. Intraclass correlation of volume measurements in CA1 and dentate gyrus is above 0.89. Overlap in smaller hippocampal subfields is lower in magnitude (0.54 for CA2, 0.62 for CA3, 0.77 for subiculum and 0.79 for entorhinal cortex) but comparable to overlap between manual segmentations by trained human raters. These results support the feasibility of subfield-specific hippocampal morphometry in clinical studies of memory and neurodegenerative disease. PMID:20600984

  13. Accuracy of percentage of signal intensity recovery and relative cerebral blood volume derived from dynamic susceptibility-weighted, contrast-enhanced MRI in the preoperative diagnosis of cerebral tumours

    PubMed Central

    Steel, Timothy; Chaganti, Joga

    2015-01-01

    Conventional magnetic resonance imaging (MRI) is the technique of choice for diagnosis of cerebral tumours, and has become an increasingly powerful tool for their evaluation; however, the diagnosis of common contrast-enhancing lesions can be challenging, as it is sometimes impossible to differentiate them using conventional imaging. Histopathological analysis of biopsy specimens is the gold standard for diagnosis; however, there are significant risks associated with the invasive procedure and definitive diagnosis is not always achieved. Early accurate diagnosis is important, as management differs accordingly. Advanced MRI techniques have increasing utility for aiding diagnosis in a variety of clinical scenarios. Dynamic susceptibility-weighted contrast-enhanced (DSC) MRI is a perfusion imaging technique and a potentially important tool for the characterisation of cerebral tumours. The percentage of signal intensity recovery (PSR) and relative cerebral blood volume (rCBV) derived from DSC MRI provide information about tumour capillary permeability and neoangiogenesis, which can be used to characterise tumour type and grade, and distinguish tumour recurrence from treatment-related effects. Therefore, PSR and rCBV potentially represent a non-invasive means of diagnosis; however, the clinical utility of these parameters has yet to be established. We present a review of the literature to date. PMID:26475485

  14. The adverse effects of reduced cerebral perfusion on cognition and brain structure in older adults with cardiovascular disease

    PubMed Central

    Alosco, Michael L; Gunstad, John; Jerskey, Beth A; Xu, Xiaomeng; Clark, Uraina S; Hassenstab, Jason; Cote, Denise M; Walsh, Edward G; Labbe, Donald R; Hoge, Richard; Cohen, Ronald A; Sweet, Lawrence H

    2013-01-01

    Background It is well established that aging and vascular processes interact to disrupt cerebral hemodynamics in older adults. However, the independent effects of cerebral perfusion on neurocognitive function among older adults remain poorly understood. We examined the associations among cerebral perfusion, cognitive function, and brain structure in older adults with varying degrees of vascular disease using perfusion magnetic resonance imaging (MRI) arterial spin labeling (ASL). Materials and methods 52 older adults underwent neuroimaging and were administered the Mini Mental State Examination (MMSE), the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and measures of attention/executive function. ASL and T1-weighted MRI were used to quantify total brain perfusion, total brain volume (TBV), and cortical thickness. Results Regression analyses showed reduced total brain perfusion was associated with poorer performance on the MMSE, RBANS total index, immediate and delayed memory composites, and Trail Making Test B. Reduced frontal lobe perfusion was associated with worse executive and memory function. A similar pattern emerged between temporal lobe perfusion and immediate memory. Regression analyses revealed that decreased total brain perfusion was associated with smaller TBV and mean cortical thickness. Regional effects of reduced total cerebral perfusion were found on temporal and parietal lobe volumes and frontal and temporal cortical thickness. Discussion Reduced cerebral perfusion is independently associated with poorer cognition, smaller TBV, and reduced cortical thickness in older adults. Conclusion Prospective studies are needed to clarify patterns of cognitive decline and brain atrophy associated with cerebral hypoperfusion. PMID:24363966

  15. On the fallacy of quantitative segmentation for T1-weighted MRI

    NASA Astrophysics Data System (ADS)

    Plassard, Andrew J.; Harrigan, Robert L.; Newton, Allen T.; Rane, Swati; Pallavaram, Srivatsan; D'Haese, Pierre F.; Dawant, Benoit M.; Claassen, Daniel O.; Landman, Bennett A.

    2016-03-01

    T1-weighted magnetic resonance imaging (MRI) generates contrasts with primary sensitivity to local T1 properties (with lesser T2 and PD contributions). The observed signal intensity is determined by these local properties and the sequence parameters of the acquisition. In common practice, a range of acceptable parameters is used to ensure "similar" contrast across scanners used for any particular study (e.g., the ADNI standard MPRAGE). However, different studies may use different ranges of parameters and report the derived data as simply "T1-weighted". Physics and imaging authors pay strong heed to the specifics of the imaging sequences, but image processing authors have historically been more lax. Herein, we consider three T1-weighted sequences acquired the same underlying protocol (MPRAGE) and vendor (Philips), but "normal study-to-study variation" in parameters. We show that the gray matter/white matter/cerebrospinal fluid contrast is subtly but systemically different between these images and yields systemically different measurements of brain volume. The problem derives from the visually apparent boundary shifts, which would also be seen by a human rater. We present and evaluate two solutions to produce consistent segmentation results across imaging protocols. First, we propose to acquire multiple sequences on a subset of the data and use the multi-modal imaging as atlases to segment target images any of the available sequences. Second (if additional imaging is not available), we propose to synthesize atlases of the target imaging sequence and use the synthesized atlases in place of atlas imaging data. Both approaches significantly improve consistency of target labeling.

  16. Diffusion, Perfusion, and Histopathologic Characteristics of Desmoplastic Infantile Ganglioglioma

    PubMed Central

    Ho, Chang Y; Gener, Melissa; Bonnin, Jose; Kralik, Stephen F

    2016-01-01

    We present a case series of a rare tumor, the desmoplastic infantile ganglioglioma (DIG) with MRI diffusion and perfusion imaging quantification as well as histopathologic characterization. Four cases with pathologically-proven DIG had diffusion weighted imaging (DWI) and two of the four had dynamic susceptibility contrast imaging. All four tumors demonstrate DWI findings compatible with low-grade pediatric tumors. For the two cases with perfusion imaging, a higher relative cerebral blood volume was associated with higher proliferation index on histopathology for one of the cases. Our results are discussed in conjunction with a literature review. PMID:27761184

  17. In vivo T2* weighted MRI visualizes cardiac lesions in murine models of acute and chronic viral myocarditis

    PubMed Central

    Helluy, Xavier; Sauter, Martina; Ye, Yu-Xiang; Lykowsky, Gunthard; Kreutner, Jakob; Yilmaz, Ali; Jahns, Roland; Boivin, Valerie; Kandolf, Reinhard; Jakob, Peter M.; Hiller, Karl-Heinz; Klingel, Karin

    2017-01-01

    Objective Acute and chronic forms of myocarditis are mainly induced by virus infections. As a consequence of myocardial damage and inflammation dilated cardiomyopathy and chronic heart failure may develop. The gold standard for the diagnosis of myocarditis is endomyocardial biopsies which are required to determine the etiopathogenesis of cardiac inflammatory processes. However, new non-invasive MRI techniques hold great potential in visualizing cardiac non-ischemic inflammatory lesions at high spatial resolution, which could improve the investigation of the pathophysiology of viral myocarditis. Results Here we present the discovery of a novel endogenous T2* MRI contrast of myocardial lesions in murine models of acute and chronic CVB3 myocarditis. The evaluation of infected hearts ex vivo and in vivo by 3D T2w and T2*w MRI allowed direct localization of virus-induced myocardial lesions without any MRI tracer or contrast agent. T2*w weighted MRI is able to detect both small cardiac lesions of acute myocarditis and larger necrotic areas at later stages of chronic myocarditis, which was confirmed by spatial correlation of MRI hypointensity in myocardium with myocardial lesions histologically. Additional in vivo and ex vivo MRI analysis proved that the contrast mechanism was due to a strong paramagnetic tissue alteration in the vicinity of myocardial lesions, effectively pointing towards iron deposits as the primary contributor of contrast. The evaluation of the biological origin of the MR contrast by specific histological staining and transmission electron microscopy revealed that impaired iron metabolism primarily in mitochondria caused iron deposits within necrotic myocytes, which induces strong magnetic susceptibility in myocardial lesions and results in strong T2* contrast. Conclusion This T2*w MRI technique provides a fast and sensitive diagnostic tool to determine the patterns and the severity of acute and chronic enteroviral myocarditis and the precise

  18. Fast pseudo-CT synthesis from MRI T1-weighted images using a patch-based approach

    NASA Astrophysics Data System (ADS)

    Torrado-Carvajal, A.; Alcain, E.; Montemayor, A. S.; Herraiz, J. L.; Rozenholc, Y.; Hernandez-Tamames, J. A.; Adalsteinsson, E.; Wald, L. L.; Malpica, N.

    2015-12-01

    MRI-based bone segmentation is a challenging task because bone tissue and air both present low signal intensity on MR images, making it difficult to accurately delimit the bone boundaries. However, estimating bone from MRI images may allow decreasing patient ionization by removing the need of patient-specific CT acquisition in several applications. In this work, we propose a fast GPU-based pseudo-CT generation from a patient-specific MRI T1-weighted image using a group-wise patch-based approach and a limited MRI and CT atlas dictionary. For every voxel in the input MR image, we compute the similarity of the patch containing that voxel with the patches of all MR images in the database, which lie in a certain anatomical neighborhood. The pseudo-CT is obtained as a local weighted linear combination of the CT values of the corresponding patches. The algorithm was implemented in a GPU. The use of patch-based techniques allows a fast and accurate estimation of the pseudo-CT from MR T1-weighted images, with a similar accuracy as the patient-specific CT. The experimental normalized cross correlation reaches 0.9324±0.0048 for an atlas with 10 datasets. The high NCC values indicate how our method can accurately approximate the patient-specific CT. The GPU implementation led to a substantial decrease in computational time making the approach suitable for real applications.

  19. Prostate cancer transrectal HIFU ablation: detection of local recurrences using T2-weighted and dynamic contrast-enhanced MRI.

    PubMed

    Rouvière, Olivier; Girouin, Nicolas; Glas, Ludivine; Ben Cheikh, Alexandre; Gelet, Albert; Mège-Lechevallier, Florence; Rabilloud, Muriel; Chapelon, Jean-Yves; Lyonnet, Denis

    2010-01-01

    The objective was to evaluate T2-weighted (T2w) and dynamic contrast-enhanced (DCE) MRI in detecting local cancer recurrences after prostate high-intensity focused ultrasound (HIFU) ablation. Fifty-nine patients with biochemical recurrence after prostate HIFU ablation underwent T2-weighted and DCE MRI before transrectal biopsy. For each patient, biopsies were performed by two operators: operator 1 (blinded to MR results) performed random and colour Doppler-guided biopsies ("routine biopsies"); operator 2 obtained up to three cores per suspicious lesion on MRI ("targeted biopsies"). Seventy-seven suspicious lesions were detected on DCE images (n = 52), T2w images (n = 2) or both (n = 23). Forty patients and 41 MR lesions were positive at biopsy. Of the 36 remaining MR lesions, 20 contained viable benign glands. Targeted biopsy detected more cancers than routine biopsy (36 versus 27 patients, p = 0.0523). The mean percentages of positive cores per patient and of tumour invasion of the cores were significantly higher for targeted biopsies (p < 0.0001). The odds ratios of the probability of finding viable cancer and viable prostate tissue (benign or malignant) at targeted versus routine biopsy were respectively 3.35 (95% CI 3.05-3.64) and 1.38 (95% CI 1.13-1.63). MRI combining T2-weighted and DCE images is a promising method for guiding post-HIFU biopsy towards areas containing recurrent cancer and viable prostate tissue.

  20. On the Fallacy of Quantitative Segmentation for T1-Weighted MRI

    PubMed Central

    Harrigan, Robert L.; Newton, Allen T.; Rane, Swati; Pallavaram, Srivatsan; D'Haese, Pierre F.; Dawant, Benoit M.; Claassen, Daniel O.; Landman, Bennett A.

    2016-01-01

    T1-weighted magnetic resonance imaging (MRI) generates contrasts with primary sensitivity to local T1 properties (with lesser T2 and PD contributions). The observed signal intensity is determined by these local properties and the sequence parameters of the acquisition. In common practice, a range of acceptable parameters is used to ensure “similar” contrast across scanners used for any particular study (e.g., the ADNI standard MPRAGE). However, different studies may use different ranges of parameters and report the derived data as simply “T1-weighted”. Physics and imaging authors pay strong heed to the specifics of the imaging sequences, but image processing authors have historically been more lax. Herein, we consider three T1-weighted sequences acquired the same underlying protocol (MPRAGE) and vendor (Philips), but “normal study-to-study variation” in parameters. We show that the gray matter/white matter/cerebrospinal fluid contrast is subtly but systemically different between these images and yields systemically different measurements of brain volume. The problem derives from the visually apparent boundary shifts, which would also be seen by a human rater. We present and evaluate two solutions to produce consistent segmentation results across imaging protocols. First, we propose to acquire multiple sequences on a subset of the data and use the multi-modal imaging as atlases to segment target images any of the available sequences. Second (if additional imaging is not available), we propose to synthesize atlases of the target imaging sequence and use the synthesized atlases in place of atlas imaging data. Both approaches significantly improve consistency of target labeling. PMID:27127328

  1. MR Susceptibility Weighted Imaging (SWI) Complements Conventional Contrast Enhanced T1 Weighted MRI in Characterizing Brain Abnormalities of Sturge-Weber Syndrome

    PubMed Central

    Hu, Jiani; Yu, Yingjian; Juhasz, Csaba; Kou, Zhifeng; Xuan, Yang; Latif, Zahid; Kudo, Kohsuke; Chugani, Harry T.; Haacke, E. Mark

    2009-01-01

    PURPOSE To evaluate the efficacy of susceptibility weighted imaging (SWI) in comparison to standard T1 weighted post gadolinium contrast (T1-Gd) MRI in patients with Sturge-Weber Syndrome (SWS). MATERIALS AND METHODS Twelve children (mean age 5.6 years) with the diagnosis of SWS and unilateral hemispheric involvement were recruited prospectively and examined with high resolution 3D SWI and conventional T1-Gd. Both SWI and T1-Gd images were evaluated using a four-grade scoring system according to six types of imaging findings (enlargement of transmedullary veins, periventricular veins and choroid plexus, as well as leptomeningeal abnormality, cortical gyriform abnormality, and gray matter/white matter junctional abnormality). The scores of SWI vs. T1-Gd images were then compared for each type of abnormality. RESULTS SWI was superior to T1-Gd in identifying the enlarged transmedullary veins (p=0.0020), abnormal periventricular veins (p=0.0078), cortical gyriform abnormalities (p=0.0020), and grey matter/white matter junction abnormalities (p=0.0078). Conversely, T1-Gd was better than SWI in identifying enlarged choroid plexus (p=0.0050) and leptomeningeal abnormalities (p=0.0050). CONCLUSION SWI can provide useful and unique information complementary to conventional contrast enhanced T1 weighted MRI for characterizing SWS. Therefore, SWI should be integrated into routine clinical MRI protocols for suspected SWS. PMID:18666142

  2. Usefulness of T2*-weighted MRI in the detection of adnexal torsion

    PubMed Central

    Kawai, Nobuyuki; Kanematsu, Masayuki; Kawaguchi, Shimpei; Kojima, Toshihisa; Furui, Tatsuro; Morishige, Ken-ichirou; Matsuo, Masayuki

    2016-01-01

    Background The usefulness of T2*-weighted (T2*W) imaging for the detection of adnexal torsion has yet to be determined. Purpose To assess the usefulness of T2*W imaging for detecting and differentiating adnexal torsion. Material and Methods Eight patients with eight ovaries with torsion and 44 patients with 72 ovaries without torsion were included in this study. All patients underwent 1.5-T magnetic resonance imaging (MRI) including T2*W images. The frequency and distribution of hypointensity on T2*W images were compared between ovaries with torsion and ovaries without torsion. Results Hypointensity on T2*W images was significantly more frequent in ovaries with torsion than in ovaries without torsion (75% vs. 36%; P < 0.05). Among patients with hypointensity on T2*W images, the frequency of diffuse hypointensity was significantly higher in ovaries with torsion than in ovaries without torsion (83% vs. 0%; P < 0.01); whereas the frequency of focal hypointensity was significantly lower in ovaries with torsion than in ovaries without torsion (17% vs. 100%; P < 0.01). Conclusion The presence and distribution of hypointensity on T2*W images may play a supplementary role in the detection of adnexal torsion. PMID:27478621

  3. Probabilistic atlas-based segmentation of combined T1-weighted and DUTE MRI for calculation of head attenuation maps in integrated PET/MRI scanners

    PubMed Central

    Poynton, Clare B; Chen, Kevin T; Chonde, Daniel B; Izquierdo-Garcia, David; Gollub, Randy L; Gerstner, Elizabeth R; Batchelor, Tracy T; Catana, Ciprian

    2014-01-01

    We present a new MRI-based attenuation correction (AC) approach for integrated PET/MRI systems that combines both segmentation- and atlas-based methods by incorporating dual-echo ultra-short echo-time (DUTE) and T1-weighted (T1w) MRI data and a probabilistic atlas. Segmented atlases were constructed from CT training data using a leave-one-out framework and combined with T1w, DUTE, and CT data to train a classifier that computes the probability of air/soft tissue/bone at each voxel. This classifier was applied to segment the MRI of the subject of interest and attenuation maps (μ-maps) were generated by assigning specific linear attenuation coefficients (LACs) to each tissue class. The μ-maps generated with this “Atlas-T1w-DUTE” approach were compared to those obtained from DUTE data using a previously proposed method. For validation of the segmentation results, segmented CT μ-maps were considered to the “silver standard”; the segmentation accuracy was assessed qualitatively and quantitatively through calculation of the Dice similarity coefficient (DSC). Relative change (RC) maps between the CT and MRI-based attenuation corrected PET volumes were also calculated for a global voxel-wise assessment of the reconstruction results. The μ-maps obtained using the Atlas-T1w-DUTE classifier agreed well with those derived from CT; the mean DSCs for the Atlas-T1w-DUTE-based μ-maps across all subjects were higher than those for DUTE-based μ-maps; the atlas-based μ-maps also showed a lower percentage of misclassified voxels across all subjects. RC maps from the atlas-based technique also demonstrated improvement in the PET data compared to the DUTE method, both globally as well as regionally. PMID:24753982

  4. Probabilistic atlas-based segmentation of combined T1-weighted and DUTE MRI for calculation of head attenuation maps in integrated PET/MRI scanners.

    PubMed

    Poynton, Clare B; Chen, Kevin T; Chonde, Daniel B; Izquierdo-Garcia, David; Gollub, Randy L; Gerstner, Elizabeth R; Batchelor, Tracy T; Catana, Ciprian

    2014-01-01

    We present a new MRI-based attenuation correction (AC) approach for integrated PET/MRI systems that combines both segmentation- and atlas-based methods by incorporating dual-echo ultra-short echo-time (DUTE) and T1-weighted (T1w) MRI data and a probabilistic atlas. Segmented atlases were constructed from CT training data using a leave-one-out framework and combined with T1w, DUTE, and CT data to train a classifier that computes the probability of air/soft tissue/bone at each voxel. This classifier was applied to segment the MRI of the subject of interest and attenuation maps (μ-maps) were generated by assigning specific linear attenuation coefficients (LACs) to each tissue class. The μ-maps generated with this "Atlas-T1w-DUTE" approach were compared to those obtained from DUTE data using a previously proposed method. For validation of the segmentation results, segmented CT μ-maps were considered to the "silver standard"; the segmentation accuracy was assessed qualitatively and quantitatively through calculation of the Dice similarity coefficient (DSC). Relative change (RC) maps between the CT and MRI-based attenuation corrected PET volumes were also calculated for a global voxel-wise assessment of the reconstruction results. The μ-maps obtained using the Atlas-T1w-DUTE classifier agreed well with those derived from CT; the mean DSCs for the Atlas-T1w-DUTE-based μ-maps across all subjects were higher than those for DUTE-based μ-maps; the atlas-based μ-maps also showed a lower percentage of misclassified voxels across all subjects. RC maps from the atlas-based technique also demonstrated improvement in the PET data compared to the DUTE method, both globally as well as regionally.

  5. T1-weighted MRI as a substitute to CT for refocusing planning in MR-guided focused ultrasound

    NASA Astrophysics Data System (ADS)

    Wintermark, Max; Tustison, Nicholas J.; Elias, William J.; Patrie, James T.; Xin, Wenjun; Demartini, Nicholas; Eames, Matt; Sumer, Suna; Lau, Benison; Cupino, Alan; Snell, John; Hananel, Arik; Kassell, Neal; Aubry, Jean-Francois

    2014-07-01

    Precise focusing is essential for transcranial MRI-guided focused ultrasound (TcMRgFUS) to minimize collateral damage to non-diseased tissues and to achieve temperatures capable of inducing coagulative necrosis at acceptable power deposition levels. CT is usually used for this refocusing but requires a separate study (CT) ahead of the TcMRgFUS procedure. The goal of this study was to determine whether MRI using an appropriate sequence would be a viable alternative to CT for planning ultrasound refocusing in TcMRgFUS. We tested three MRI pulse sequences (3D T1 weighted 3D volume interpolated breath hold examination (VIBE), proton density weighted 3D sampling perfection with applications optimized contrasts using different flip angle evolution and 3D true fast imaging with steady state precision T2-weighted imaging) on patients who have already had a CT scan performed. We made detailed measurements of the calvarial structure based on the MRI data and compared those so-called ‘virtual CT’ to detailed measurements of the calvarial structure based on the CT data, used as a reference standard. We then loaded both standard and virtual CT in a TcMRgFUS device and compared the calculated phase correction values, as well as the temperature elevation in a phantom. A series of Bland-Altman measurement agreement analyses showed T1 3D VIBE as the optimal MRI sequence, with respect to minimizing the measurement discrepancy between the MRI derived total skull thickness measurement and the CT derived total skull thickness measurement (mean measurement discrepancy: 0.025; 95% CL (-0.22-0.27) p = 0.825). The T1-weighted sequence was also optimal in estimating skull CT density and skull layer thickness. The mean difference between the phase shifts calculated with the standard CT and the virtual CT reconstructed from the T1 dataset was 0.08 ± 1.2 rad on patients and 0.1 ± 0.9 rad on phantom. Compared to the real CT, the MR-based correction showed a 1 °C drop on the maximum

  6. T1-weighted MRI as a substitute to CT for refocusing planning in MR-guided focused ultrasound.

    PubMed

    Wintermark, Max; Tustison, Nicholas J; Elias, William J; Patrie, James T; Xin, Wenjun; Demartini, Nicholas; Eames, Matt; Sumer, Suna; Lau, Benison; Cupino, Alan; Snell, John; Hananel, Arik; Kassell, Neal; Aubry, Jean-Francois

    2014-07-07

    Precise focusing is essential for transcranial MRI-guided focused ultrasound (TcMRgFUS) to minimize collateral damage to non-diseased tissues and to achieve temperatures capable of inducing coagulative necrosis at acceptable power deposition levels. CT is usually used for this refocusing but requires a separate study (CT) ahead of the TcMRgFUS procedure. The goal of this study was to determine whether MRI using an appropriate sequence would be a viable alternative to CT for planning ultrasound refocusing in TcMRgFUS. We tested three MRI pulse sequences (3D T1 weighted 3D volume interpolated breath hold examination (VIBE), proton density weighted 3D sampling perfection with applications optimized contrasts using different flip angle evolution and 3D true fast imaging with steady state precision T2-weighted imaging) on patients who have already had a CT scan performed. We made detailed measurements of the calvarial structure based on the MRI data and compared those so-called 'virtual CT' to detailed measurements of the calvarial structure based on the CT data, used as a reference standard. We then loaded both standard and virtual CT in a TcMRgFUS device and compared the calculated phase correction values, as well as the temperature elevation in a phantom. A series of Bland-Altman measurement agreement analyses showed T1 3D VIBE as the optimal MRI sequence, with respect to minimizing the measurement discrepancy between the MRI derived total skull thickness measurement and the CT derived total skull thickness measurement (mean measurement discrepancy: 0.025; 95% CL (-0.22-0.27); p = 0.825). The T1-weighted sequence was also optimal in estimating skull CT density and skull layer thickness. The mean difference between the phase shifts calculated with the standard CT and the virtual CT reconstructed from the T1 dataset was 0.08 ± 1.2 rad on patients and 0.1 ± 0.9 rad on phantom. Compared to the real CT, the MR-based correction showed a 1 °C drop on the maximum

  7. 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.

  8. Dynamic contrast-enhanced MRI in mouse tumors at 11.7 T: comparison of three contrast agents with different molecular weights to assess the early effects of combretastatin A4.

    PubMed

    Fruytier, A-C; Magat, J; Neveu, M-A; Karroum, O; Bouzin, C; Feron, O; Jordan, B; Cron, G O; Gallez, B

    2014-11-01

    Dynamic contrast-enhanced (DCE)-MRI is useful to assess the early effects of drugs acting on tumor vasculature, namely anti-angiogenic and vascular disrupting agents. Ultra-high-field MRI allows higher-resolution scanning for DCE-MRI while maintaining an adequate signal-to-noise ratio. However, increases in susceptibility effects, combined with decreases in longitudinal relaxivity of gadolinium-based contrast agents (GdCAs), make DCE-MRI more challenging at high field. The aim of this work was to explore the feasibility of using DCE-MRI at 11.7 T to assess the tumor hemodynamics of mice. Three GdCAs possessing different molecular weights (gadoterate: 560 Da, 0.29 mmol Gd/kg; p846: 3.5 kDa, 0.10 mmol Gd/kg; and p792: 6.47 kDa, 0.15 mmol Gd/kg) were compared to see the influence of the molecular weight in the highlight of the biologic effects induced by combretastatin A4 (CA4). Mice bearing transplantable liver tumor (TLT) hepatocarcinoma were divided into two groups (n = 5-6 per group and per GdCA): a treated group receiving 100 mg/kg CA4, and a control group receiving vehicle. The mice were imaged at 11.7 T with a T1 -weighted FLASH sequence 2 h after the treatment. Individual arterial input functions (AIFs) were computed using phase imaging. These AIFs were used in the Extended Tofts Model to determine K(trans) and vp values. A separate immunohistochemistry study was performed to assess the vascular perfusion and the vascular density. Phase imaging was used successfully to measure the AIF for the three GdCAs. In control groups, an inverse relationship between the molecular weight of the GdCA and K(trans) and vp values was observed. K(trans) was significantly decreased in the treated group compared with the control group for each GdCA. DCE-MRI at 11.7 T is feasible to assess tumor hemodynamics in mice. With K(trans) , the three GdCAs were able to track the early vascular effects induced by CA4 treatment.

  9. 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

  10. Theoretical considerations in measurement of time discrepancies between input and myocardial time-signal intensity curves in estimates of regional myocardial perfusion with first-pass contrast-enhanced MRI.

    PubMed

    Natsume, Takahiro; Ishida, Masaki; Kitagawa, Kakuya; Nagata, Motonori; Sakuma, Hajime; Ichihara, Takashi

    2015-11-01

    The purpose of this study was to develop a method to determine time discrepancies between input and myocardial time-signal intensity (TSI) curves for accurate estimation of myocardial perfusion with first-pass contrast-enhanced MRI. Estimation of myocardial perfusion with contrast-enhanced MRI using kinetic models requires faithful recording of contrast content in the blood and myocardium. Typically, the arterial input function (AIF) is obtained by setting a region of interest in the left ventricular cavity. However, there is a small delay between the AIF and the myocardial curves, and such time discrepancies can lead to errors in flow estimation using Patlak plot analysis. In this study, the time discrepancies between the arterial TSI curve and the myocardial tissue TSI curve were estimated based on the compartment model. In the early phase after the arrival of the contrast agent in the myocardium, the relationship between rate constant K1 and the concentrations of Gd-DTPA contrast agent in the myocardium and arterial blood (LV blood) can be described by the equation K1={dCmyo(tpeak)/dt}/Ca(tpeak), where Cmyo(t) and Ca(t) are the relative concentrations of Gd-DTPA contrast agent in the myocardium and in the LV blood, respectively, and tpeak is the time corresponding to the peak of Ca(t). In the ideal case, the time corresponding to the maximum upslope of Cmyo(t), tmax, is equal to tpeak. In practice, however, there is a small difference in the arrival times of the contrast agent into the LV and into the myocardium. This difference was estimated to correspond to the difference between tpeak and tmax. The magnitudes of such time discrepancies and the effectiveness of the correction for these time discrepancies were measured in 18 subjects who underwent myocardial perfusion MRI under rest and stress conditions. The effects of the time discrepancies could be corrected effectively in the myocardial perfusion estimates.

  11. Intravoxel incoherent motion diffusion‐weighted MRI during chemoradiation therapy to characterize and monitor treatment response in human papillomavirus head and neck squamous cell carcinoma

    PubMed Central

    Paudyal, Ramesh; Oh, Jung Hun; Riaz, Nadeem; Venigalla, Praveen; Li, Jingao; Hatzoglou, Vaios; Leeman, Jonathan; Nunez, David Aramburu; Lu, Yonggang; Deasy, Joseph O.; Lee, Nancy

    2016-01-01

    Purpose Characterize and monitor treatment response in human papillomavirus (HPV) head and neck squamous cell carcinoma (HNSCC) using intra‐treatment (intra‐TX) imaging metrics derived from intravoxel incoherent motion (IVIM) diffusion‐weighted magnetic resonance imaging (DW‐MRI). Materials and Methods Thirty‐four (30 HPV positive [+] and 4 HPV negative [‐]) HNSCC patients underwent a total of 136 MRI including multi‐b value DW‐MRI (pretreatment [pre‐TX] and intra‐TX weeks 1, 2, and 3) at 3.0 Tesla. All patients were treated with chemo‐radiation therapy. Monoexponential (yielding apparent diffusion coefficient [ADC]) and bi‐exponential (yielding perfusion fraction [f], diffusion [D], and pseudo‐diffusion [D*] coefficients) fits were performed on a region of interest and voxel‐by‐voxel basis, on metastatic neck nodes. Response was assessed using RECISTv1.1. The relative percentage change in D, f, and D* between the pre‐ and intra‐TX weeks were used for hierarchical clustering. A Wilcoxon rank‐sum test was performed to assess the difference in metrics within and between the complete response (CR) and non‐CR groups. Results The delta (Δ) change in volume (V)1wk‐0wk for the CR group differed significantly (P = 0.016) from the non‐CR group, while not for V2wk‐0wk and V3wk‐0wk (P > 0.05). The mean increase in ΔD3wk‐0wk for the CR group was significantly higher (P = 0.017) than the non‐CR group. ADC and D showed an increasing trend at each intra‐TX week when compared with pre‐TX in CR group (P < 0.003). Hierarchical clustering demonstrated the existence of clusters in HPV + patients. Conclusion After appropriate validation in a larger population, these IVIM imaging metrics may be useful for individualized treatment in HNSCC patients. Level of Evidence: 2 J. Magn. Reson. Imaging 2017;45:1013–1023 PMID:27862553

  12. Automatic brain tumor extraction from T1-weighted coronal MRI using fast bounding box and dynamic snake.

    PubMed

    Xu, Tao; Mandal, Mrinal

    2012-01-01

    Brain tumor segmentation from MRI data is an important but challenging task. This paper presents an efficient and fully automatic brain tumor segmentation technique. The proposed technique includes a fuzzy C-means (FCM) based preprocessing to enhance the quality of T1-weighted coronal MR images, a fast bounding box (FBB) detection algorithm to locate a rectangle around tumor, and a new dynamic snake using modified Hausdorff distance (MHD) for the final tumor extraction.

  13. M2 occlusions as targets for endovascular therapy: comprehensive analysis of diffusion/perfusion MRI, angiography, and clinical outcomes

    PubMed Central

    Sheth, Sunil A; Yoo, Bryan; Saver, Jeffrey L; Starkman, Sidney; Ali, Latisha K; Kim, Doojin; Gonzalez, Nestor R; Jahan, Reza; Tateshima, Satoshi; Duckwiler, Gary; Vinuela, Fernando; Liebeskind, David S

    2014-01-01

    Background The ideal population of patients for endovascular therapy (ET) in acute ischemic stroke remains undefined. Recent ET trials have moved towards selecting patients with proximal middle cerebral artery (MCA) or internal carotid artery occlusions, which will likely leave a gap in our understanding of the treatment outcomes of M2 occlusions. Objective and methods To examine the presentation, treatment, and outcomes of M2 compared with M1 MCA occlusions in patients undergoing ET by assessing comprehensive MRI, angiography, and clinical data. Results We found that M2 occlusions can lead to massive strokes defined by hypoperfused and infarcted volumes as well as death or moderate to severe disability in nearly 50% of patients at discharge. Compared with M1 occlusions, M2 occlusions achieved similar Thrombolysis in Cerebral Infarction (TICI) 2b/3 recanalization rates, with significantly less hemorrhage. M2 occlusions presented with smaller infarct and hypoperfused volumes and had smaller final infarct volumes regardless of recanalization. TICI 2b/3 recanalization of M2 occlusions was associated with smaller infarct volumes compared with TICI 0–2a recanalization, as well as less infarct expansion, in patients who received IV tissue plasminogen activator as well as those that did not. Successful reperfusion of M2 occlusions was associated with improved discharge modified Rankin scale. Conclusions If suitable as targets of ET, M2 occlusions should be given the same consideration as M1 occlusions. PMID:24821842

  14. No evidence of perfusion abnormalities in the basal ganglia of a patient with generalized chorea-ballism and polycythaemia vera: analysis using subtraction SPECT co-registered to MRI.

    PubMed

    Kim, Woojun; Kim, Joong-Seok; Lee, Kwang-Soo; Kim, Yeong-In; Park, Chong-Won; Chung, Yong-An

    2008-10-01

    Polycythaemia vera is a well-known cause of symptomatic chorea, however, the pathophysiology of this correlation remains unclear. We report on a patient with generalized chorea-ballism associated with polycythaemia vera, and we present the findings of 99mTc-hexamethylpropylene amine oxime (HMPAO) SPECT done in both the choreic state and the non-choreic state. The SPECT during both the choreic and the non-choreic states did not reveal any definite perfusion changes in specific regions of the brain, as compared with 6 age-matched controls. In addition, the subtraction SPECT co-registered to MRI (SISCOM) analysis did not show any difference in cerebral blood flow during the choreic and non-choreic states. This result suggests that the basic mechanism of chorea associated with polycythaemia vera does not appear to be associated with a reduction in cerebral perfusion to a specific cerebral area, such as the basal ganglia or its thalamocortical connections.

  15. Using longitudinal metamorphosis to examine ischemic stroke lesion dynamics on perfusion-weighted images and in relation to final outcome on T2-w images

    PubMed Central

    Rekik, Islem; Allassonnière, Stéphanie; Carpenter, Trevor K.; Wardlaw, Joanna M.

    2014-01-01

    We extend the image-to-image metamorphosis into constrained longitudinal metamorphosis. We apply it to estimate an evolution scenario, in patients with acute ischemic stroke, of both scattered and solitary ischemic lesions visible on serial MR perfusion weighted imaging from acute to subacute stages. We then estimate a patient-specific residual map that enables us to capture the most relevant shape and intensity changes, continuously, as the lesion evolves from acute through subacute to chronic timepoints until merging into the final image. We detect areas with high residuals (i.e., high dynamics) and identify areas that became part of the final T2-w lesion obtained at ≥ 1 month after stroke. This allows the investigation of the dynamic influence of perfusion values on the final lesion outcome as seen on T2-w imaging. The model provides detailed insights into stroke lesion dynamic evolution in space and time that will help identify factors that determine final outcome and identify targets for interventions to improve outcome. PMID:25161899

  16. Comparison of Diffuse Weighted Imaging and Fluid Attenuation Inversion Recovery Sequences of MRI in Brain Multiple Sclerosis Plaques Detection

    PubMed Central

    NAFISI-MOGHADAM, Reza; RAHIMDEL, Abolghasem; SHANBEHZADEH, Tahereh; FALLAH, Razieh

    2017-01-01

    Objective Suitable magnetic resonance imaging (MRI) techniques from conventional to new devices can help physicians in diagnosis and follow up of Multiple Sclerosis (MS) patients. The aim of present research was to compare effectiveness of Fluid Attenuation Inversion Recovery (FLAIR) sequence of conventional MRI and Diffuse Weighted Imaging (DWI) sequence as a new technique in detection of brain MS plaques. Materials & Methods In this analytic cross sectional study, sample size was assessed as 40 people to detect any significant difference between two sequences with a level of 0.05. DWI and FLAIR sequences of without contrast brain MRI of consecutive MS patients referred to MRI center of Shahid Sadoughi Hospital, Yazd, Iran from January to May 2012, were evaluated. Results Thirty-two females and 8 males with mean age of 35.20±9.80 yr (range = 11-66 yr) were evaluated and finally 340 plaques including 127(37.2%) in T2WI, 127(37.2%) in FLAIR, 63(18.5%) in DWI and 24(7.1%) in T1WI were detected. FLAIR sequence was more efficient than DWI in detection of brain MS plaques, oval, round, amorphous plaque shapes, frontal and occipital lobes, periventricular, intracapsular, corpus callosum, centrum semiovale, subcortical, basal ganglia plaques and diameter of detected MS plaques in DWI sequence was smaller than in FLAIR. Conclusion Old lesion can be detected by conventional MRI and new techniques might be more useful in early inflammatory phase of MS and assessment of experimental treatments. PMID:28277551

  17. Evaluating the Role of Reduced Oxygen Saturation and Vascular Damage in Traumatic Brain Injury Using Magnetic Resonance Perfusion-Weighted Imaging and Susceptibility-Weighted Imaging and Mapping.

    PubMed

    Kou, Zhifeng; Ye, Yongquan; Haacke, Ewart Mark

    2015-10-01

    The cerebral vasculature, along with neurons and axons, is vulnerable to biomechanical insult during traumatic brain injury (TBI). Trauma-induced vascular injury is still an underinvestigated area in TBI research. Cerebral blood flow and metabolism could be important future treatment targets in neural critical care. Magnetic resonance imaging offers a number of key methods to probe vascular injury and its relationship with traumatic hemorrhage, perfusion deficits, venous blood oxygen saturation changes, and resultant tissue damage. They make it possible to image the hemodynamics of the brain, monitor regional damage, and potentially show changes induced in the brain's function not only acutely but also longitudinally following treatment. These methods have recently been used to show that even mild TBI (mTBI) subjects can have vascular abnormalities, and thus they provide a major step forward in better diagnosing mTBI patients.

  18. Detection of ischaemic myocardial lesions with coronary CT angiography and adenosine-stress dynamic perfusion imaging using a 128-slice dual-source CT: diagnostic performance in comparison with cardiac MRI

    PubMed Central

    Kim, S M; Choi, J-H; Chang, S-A

    2013-01-01

    Objective: We assessed the diagnostic performance of adenosine-stress dynamic CT perfusion (ASDCTP) imaging and coronary CT angiography (CCTA) for the detection of ischaemic myocardial lesions using 128-slice dual-source CT compared with that of 1.5 T cardiac MRI. Methods: This prospective study included 33 patients (61±8 years, 82% male) with suspected coronary artery diseases who underwent ASDCTP imaging and adenosine-stress cardiac MRI. Two investigators independently evaluated ASDCTP images in correlation with significant coronary stenosis on CCTA using two different thresholds of 50% and 70% diameter stenosis. Hypoattenuated myocardial lesions on ASDCTP associated with significant coronary stenoses on CCTA were regarded as true perfusion defects. All estimates of diagnostic performance were calculated and compared with those of cardiac MRI. Results: With use of a threshold of 50% diameter stenosis on CCTA, the diagnostic estimates per-myocardial segment were as follows: sensitivity, 81% [95% confidence interval (CI): 70–92%]; specificity, 94% (95% CI: 92–96%); and accuracy 93% (95% CI: 91–95%). With use of a threshold of 70%, the diagnostic estimates were as follows: sensitivity, 48% (95% CI: 34–62%); specificity, 99% (95% CI: 98–100%); and accuracy, 94% (95% CI: 92–96%). Conclusion: Dynamic CTP using 128-slice dual-source CT enables the assessment of the physiological significance of coronary artery lesions with high diagnostic accuracy in patients with clinically suspected coronary artery disease. Advances in knowledge: Combined CCTA and ASDCTP yielded high accuracy in the detection of perfusion defects regardless of the threshold of significant coronary stenosis. PMID:24096592

  19. Evaluation of T2-weighted and dynamic contrast-enhanced MRI in localizing prostate cancer before repeat biopsy.

    PubMed

    Cheikh, Alexandre Ben; Girouin, Nicolas; Colombel, Marc; Maréchal, Jean-Marie; Gelet, Albert; Bissery, Alvine; Rabilloud, Muriel; Lyonnet, Denis; Rouvière, Olivier

    2009-03-01

    We assessed the accuracy of T2-weighted (T2w) and dynamic contrast-enhanced (DCE) 1.5-T magnetic resonance imaging (MRI) in localizing prostate cancer before transrectal ultrasound-guided repeat biopsy. Ninety-three patients with abnormal PSA level and negative prostate biopsy underwent T2w and DCE prostate MRI using pelvic coil before repeat biopsy. T2w and DCE images were interpreted using visual criteria only. MR results were correlated with repeat biopsy findings in ten prostate sectors. Repeat biopsy found prostate cancer in 23 patients (24.7%) and 44 sectors (6.6%). At per patient analysis, the sensitivity, specificity, positive and negative predictive values were 47.8%, 44.3%, 20.4% and 79.5% for T2w imaging and 82.6%, 20%, 24.4% and 93.3% for DCE imaging. When all suspicious areas (on T2w or DCE imaging) were taken into account, a sensitivity of 82.6% and a negative predictive value of 100% could be achieved. At per sector analysis, DCE imaging was significantly less specific (83.5% vs. 89.7%, p < 0.002) than T2w imaging; it was more sensitive (52.4% vs. 32.1%), but the difference was hardly significant (p = 0.09). T2w and DCE MRI using pelvic coil and visual diagnostic criteria can guide prostate repeat biopsy, with a good sensitivity and NPV.

  20. Evaluation of Fat Suppression of Diffusion-weighted Imaging Using Section Select Gradient Reversal Technique on 3 T Breast MRI.

    PubMed

    Takemori, Daichi; Kimura, Daisuke; Yamada, Eiji; Higashida, Mitsuji

    2016-07-01

    This study evaluates fat suppression of diffusion-weighted imaging (DWI) using section select gradient reversal (SSGR) technique in clinical images on 3 T breast MRI. A total of 20 patients with breast cancer were examined at a Philips Ingenia 3 T MRI. We acquired DWI with SPAIR, SSGR-SPAIR, STIR, and SSGR-STIR. We evaluated contrast between the fat region and lesion, the coefficient of variance (CV) of the fat region and the apparent diffusion coefficient (ADC) of normal breast tissue and lesion. The contrast between the fat region and lesion was improved with SSGR technique. The CV of the fattest region did not have any significant difference in SPAIR technique (p>0.05), but it was significantly decreased in the STIR technique using SSGR technique (p<0.05). Positive correlation was observed in ADC value between SPAIR and other fat suppression techniques (SSGR-SPAIR, STIR, SSGR-STIR). DWI using SSGR technique was suggested to be effective on 3 T breast MRI.

  1. Brain Tissue Compartment Density Estimated Using Diffusion-Weighted MRI Yields Tissue Parameters Consistent With Histology

    PubMed Central

    Sepehrband, Farshid; Clark, Kristi A.; Ullmann, Jeremy F.P.; Kurniawan, Nyoman D.; Leanage, Gayeshika; Reutens, David C.; Yang, Zhengyi

    2015-01-01

    We examined whether quantitative density measures of cerebral tissue consistent with histology can be obtained from diffusion magnetic resonance imaging (MRI). By incorporating prior knowledge of myelin and cell membrane densities, absolute tissue density values were estimated from relative intra-cellular and intra-neurite density values obtained from diffusion MRI. The NODDI (neurite orientation distribution and density imaging) technique, which can be applied clinically, was used. Myelin density estimates were compared with the results of electron and light microscopy in ex vivo mouse brain and with published density estimates in a healthy human brain. In ex vivo mouse brain, estimated myelin densities in different sub-regions of the mouse corpus callosum were almost identical to values obtained from electron microscopy (Diffusion MRI: 42±6%, 36±4% and 43±5%; electron microscopy: 41±10%, 36±8% and 44±12% in genu, body and splenium, respectively). In the human brain, good agreement was observed between estimated fiber density measurements and previously reported values based on electron microscopy. Estimated density values were unaffected by crossing fibers. PMID:26096639

  2. 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

  3. Comparative study of microelectrode recording-based STN location and MRI-based STN location in low to ultra-high field (7.0 T) T2-weighted MRI images

    NASA Astrophysics Data System (ADS)

    Verhagen, Rens; Schuurman, P. Richard; van den Munckhof, Pepijn; Fiorella Contarino, M.; de Bie, Rob M. A.; Bour, Lo J.

    2016-12-01

    Objective. The correspondence between the anatomical STN and the STN observed in T2-weighted MRI images used for deep brain stimulation (DBS) targeting remains unclear. Using a new method, we compared the STN borders seen on MRI images with those estimated by intraoperative microelectrode recordings (MER). Approach. We developed a method to automatically generate a detailed estimation of STN shape and the location of its borders, based on multiple-channel MER measurements. In 33 STNs of 19 Parkinson patients, we quantitatively compared the dorsal and lateral borders of this MER-based STN model with the STN borders visualized by 1.5 T (n = 14), 3.0 T (n = 10) and 7.0 T (n = 9) T2-weighted MRI. Main results. The dorsal border was identified more dorsally on coronal T2 MRI than by the MER-based STN model, with a significant difference in the 3.0 T (range 0.97-1.19 mm) and 7.0 T (range 1.23-1.25 mm) groups. The lateral border was significantly more medial on 1.5 T (mean: 1.97 mm) and 3.0 T (mean: 2.49 mm) MRI than in the MER-based STN; a difference that was not found in the 7.0 T group. Significance. The STN extends further in the dorsal direction on coronal T2 MRI images than is measured by MER. Increasing MRI field strength to 3.0 T or 7.0 T yields similar discrepancies between MER and MRI at the dorsal STN border. In contrast, increasing MRI field strength to 7.0 T may be useful for identification of the lateral STN border and thereby improve DBS targeting.

  4. Advanced MR imaging techniques in the evaluation of nonenhancing gliomas: perfusion-weighted imaging compared with proton magnetic resonance spectroscopy and tumor grade.

    PubMed

    Sahin, Neslin; Melhem, Elias R; Wang, Sumei; Krejza, Jaroslaw; Poptani, Harish; Chawla, Sanjeev; Verma, Gaurav

    2013-10-01

    A significant number of nonenhancing (NE) gliomas are reported to be malignant. The purpose of this study was to compare the value of advanced MR imaging techniques, including T2*-dynamic susceptibility contrast PWI (DSC-PWI) and proton magnetic resonance spectroscopy ((1)HMRS) in the evaluation of NE gliomas. Twenty patients with NE gliomas underwent MRI including DSC-PWI and (1)HMRS. The relative CBV (rCBV) measurements were obtained from regions of maximum perfusion. The peak ratios of choline/creatine (Cho/Cr) and myo-inositol/creatine (mIns/Cr) were measured at a TE of 30 ms. Demographic features, tumor volumes, and PWI- and (1)HMRS-derived measures were compared between low-grade gliomas (LGGs) and high-grade gliomas (HGGs). In addition, the association of initial rCBV ratio with tumor progression was evaluated in LGGs. No significant difference was noted in age, sex or tumor size between LGGs and HGGs. Cho/Cr ratios were significantly higher in HGGs (1.7±0.63) than in LGGs (1.2±0.38). The receiver operating characteristic analysis demonstrated that a Cho/Cr ratio with a cutoff value of 1.3 could differentiate between LGG and HGG with a specificity of 100% and a sensitivity of 71.4%. There was no significant difference in the rCBV ratio and the mIns/Cr ratio between LGG and HGG. However, higher rCBV ratios were observed with more rapid progressions in LGGs. The results imply that Cho/Cr ratios are useful in distinguishing NE LGG from HGG and can be helpful in preoperative grading and biopsy guidance. On the other hand, rCBV ratios do not help in the distinction.

  5. Immunochemotherapy with Intensive Consolidation for Primary CNS Lymphoma: A Pilot Study and Prognostic Assessment by Diffusion-Weighted MRI

    PubMed Central

    Wieduwilt, Matthew J.; Valles, Francisco; Issa, Samar; Behler, Caroline M.; Hwang, James; McDermott, Michael; Treseler, Patrick; O’Brien, Joan; Shuman, Marc A.; Cha, Soonmee; Damon, Lloyd E.; Rubenstein, James L.

    2012-01-01

    Purpose We evaluated a novel therapy for primary central nervous system (CNS) lymphoma (PCNSL) using induction immunochemotherapy with high-dose methotrexate, temozolomide and rituximab (MT-R) followed by intensive consolidation with infusional etoposide and high-dose cytarabine (EA). In addition, we evaluated the prognostic value of the minimum apparent diffusion coefficient (ADCmin) derived from diffusion-weighted magnetic resonance imaging (DW-MRI) in patients treated with this regimen. Experimental Design Thirty-one patients (median age, 61; median KPS, 60) received induction with methotrexate every 14 days for 8 planned cycles. Rituximab was administered the first 6 cycles and temozolomide administered on odd-numbered cycles. Patients with responsive or stable CNS disease received EA consolidation. Pretreatment DW-MRI was used to calculate the ADCmin of contrast-enhancing lesions. Results The complete response rate for MT-R induction was 52%. At a median follow-up of 79 months, the 2-year progression-free and overall survival were 45% and 58%, respectively. For patients receiving EA consolidation, the 2-year progression-free and overall survival were 78% and 93%, respectively. EA consolidation was also effective in an additional 3 patients who presented with synchronous CNS and systemic lymphoma. Tumor ADCmin <384 × 10−6 mm2/s was significantly associated with shorter progression-free and overall survival. Conclusions MT-R induction was effective and well-tolerated. MT-R followed by EA consolidation yielded progression-free and overall survival outcomes comparable to regimens using chemotherapy followed by whole-brain radiotherapy consolidation but without evidence of neurotoxicity. Tumor ADCmin derived from DW-MRI provided better prognostic information for PCNSL patients treated with the MTR-EA regimen than established clinical risk scores. PMID:22228634

  6. Advanced MRI for Pediatric Brain Tumors with Emphasis on Clinical Benefits

    PubMed Central

    Ra, Young-Shin

    2017-01-01

    Conventional anatomic brain MRI is often limited in evaluating pediatric brain tumors, the most common solid tumors and a leading cause of death in children. Advanced brain MRI techniques have great potential to improve diagnostic performance in children with brain tumors and overcome diagnostic pitfalls resulting from diverse tumor pathologies as well as nonspecific or overlapped imaging findings. Advanced MRI techniques used for evaluating pediatric brain tumors include diffusion-weighted imaging, diffusion tensor imaging, functional MRI, perfusion imaging, spectroscopy, susceptibility-weighted imaging, and chemical exchange saturation transfer imaging. Because pediatric brain tumors differ from adult counterparts in various aspects, MRI protocols should be designed to achieve maximal clinical benefits in pediatric brain tumors. In this study, we review advanced MRI techniques and interpretation algorithms for pediatric brain tumors. PMID:28096729

  7. Reproducibility of Kidney Perfusion Measurements With Arterial Spin Labeling at 1.5 Tesla MRI Combined With Semiautomatic Segmentation for Differential Cortical and Medullary Assessment

    PubMed Central

    Hammon, Matthias; Janka, Rolf; Siegl, Christian; Seuss, Hannes; Grosso, Roberto; Martirosian, Petros; Schmieder, Roland E.; Uder, Michael; Kistner, Iris

    2016-01-01

    Abstract Magnetic resonance imaging with arterial spin labeling (ASL) is a noninvasive approach to measure organ perfusion. The purpose of this study was to evaluate the reproducibility of ASL kidney perfusion measurements with semiautomatic segmentation, which allows separate quantification of cortical and medullary perfusion. The right kidneys of 14 healthy volunteers were examined 6 times on 2 occasions (3 times at each occasion). There was a 10-minute pause between each examination and a 14-day interval between the 2 occasions. Cortical, medullary, and whole kidney parenchymal perfusion was determined with customized semiautomatic segmentation software. Coefficient of variances (CVs) and intraclass correlations (ICCs) were calculated. Mean whole, cortical, and medullary kidney perfusion was 307.26 ± 25.65, 337.10 ± 34.83, and 279.61 ± 26.73 mL/min/100 g, respectively. On session 1, mean perfusion for the whole kidney, cortex, and medulla was 307.08 ± 26.91, 336.79 ± 36.54, and 279.60 ± 27.81 mL/min/100 g, respectively, and on session 2, 307.45 ± 24.65, 337.41 ± 33.48, and 279.61 ± 25.94 mL/min/100 g, respectively (P > 0.05; R2 = 0.60/0.59/0.54). For whole, cortical, and medullary kidney perfusion, the total ICC/CV were 0.97/3.43 ± 0.86%, 0.97/4.19 ± 1.33%, and 0.96/4.12 ± 1.36%, respectively. Measurements did not differ significantly and showed a very good correlation (P > 0.05; R2 = 0.75/0.76/0.65). ASL kidney measurements combined with operator-independent semiautomatic segmentation revealed high correlation and low variance of cortical, medullary, and whole kidney perfusion. PMID:26986143

  8. Resource atlases for multi-atlas brain segmentations with multiple ontology levels based on T1-weighted MRI.

    PubMed

    Wu, Dan; Ma, Ting; Ceritoglu, Can; Li, Yue; Chotiyanonta, Jill; Hou, Zhipeng; Hsu, John; Xu, Xin; Brown, Timothy; Miller, Michael I; Mori, Susumu

    2016-01-15

    Technologies for multi-atlas brain segmentation of T1-weighted MRI images have rapidly progressed in recent years, with highly promising results. This approach, however, relies on a large number of atlases with accurate and consistent structural identifications. Here, we introduce our atlas inventories (n=90), which cover ages 4-82years with unique hierarchical structural definitions (286 structures at the finest level). This multi-atlas library resource provides the flexibility to choose appropriate atlases for various studies with different age ranges and structure-definition criteria. In this paper, we describe the details of the atlas resources and demonstrate the improved accuracy achievable with a dynamic age-matching approach, in which atlases that most closely match the subject's age are dynamically selected. The advanced atlas creation strategy, together with atlas pre-selection principles, is expected to support the further development of multi-atlas image segmentation.

  9. Relationship between pretreatment FDG-PET and diffusion-weighted MRI biomarkers in diffuse large B-cell lymphoma

    PubMed Central

    de Jong, Antoinette; Kwee, Thomas C; de Klerk, John MH; Adam, Judit A; de Keizer, Bart; Fijnheer, Rob; Kersten, Marie José; Ludwig, Inge; Jauw, Yvonne WS; Zijlstra, Josée M; den Bos, Indra C Pieters - Van; Stoker, Jaap; Hoekstra, Otto S; Nievelstein, Rutger AJ

    2014-01-01

    The purpose of this study was to determine the correlation between the 18F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) standardized uptake value (SUV) and the diffusion-weighted magnetic resonance imaging (MRI) apparent diffusion coefficient (ADC) in newly diagnosed diffuse large B-cell lymphoma (DLBCL). Pretreatment FDG-PET and diffusion-weighted MRI of 21 patients with histologically proven DLBCL were prospectively analyzed. In each patient, maximum, mean and peak standardized uptake value (SUV) was measured in the lesion with visually highest FDG uptake and in the largest lesion. Mean ADC (ADCmean, calculated with b-values of 0 and 1000 s/mm2) was measured in the same lesions. Correlations between FDG-PET metrics (SUVmax, SUVmean, SUVpeak) and ADCmean were assessed using Pearson’s correlation coefficients. In the lesions with visually highest FDG uptake, no significant correlations were found between the SUVmax, SUVmean, SUVpeak and the ADCmean (P=0.498, P=0.609 and P=0.595, respectively). In the largest lesions, there were no significant correlations either between the SUVmax, SUVmean, SUVpeak and the ADCmean (P=0.992, P=0.843 and P=0.894, respectively). The results of this study indicate that the glycolytic rate as measured by FDG-PET and changes in water compartmentalization and water diffusion as measured by the ADC are independent biological phenomena in newly diagnosed DLBCL. Further studies are warranted to assess the complementary roles of these different imaging biomarkers in the evaluation and follow-up of DLBCL. PMID:24795837

  10. Clinically silent choroid plexus cyst: evaluation by diffusion-weighted MRI.

    PubMed

    Kinoshita, Toshibumi; Moritani, Toshio; Hiwatashi, Akio; Numaguchi, Yuji; Wang, Henry Z; Westesson, Per-Lennart A; Sugihara, Shuji; Matsusue, Eiji; Fujii, Shinya; Ohama, Eisaku; Ogawa, Toshihide

    2005-04-01

    We retrospectively reviewed diffusion-weighted magnetic resonance images of 57 patients with a choroid plexus cyst diagnosed by contrast-enhanced T1-weighted imaging. All the cysts appeared to represent incidental findings. Thirty-eight of 57 patients had bilateral cysts and 19 had unilateral ones. On diffusion-weighted images, 78 of 95 cysts showed homogeneously high signal intensity, 12 showed focal high signal areas, and 5 had no portion with a high signal. The apparent diffusion coefficient of the high signal areas in the cysts was (1.46+/-0.14) x10(-3) mm(2)/s, intermediate between the apparent diffusion coefficients of cerebrospinal fluid and cerebral white matter, (3.15+/-0.67) x10(-3) and (0.79+/-0.22) x10(-3) mm(2)/s, respectively. Pathological correlation was available in one case, showing high signal intensity areas in the glomera of the choroid plexuses in the lateral ventricles on diffusion-weighted images corresponding to gelatinous cysts with highly proteinaceous content.

  11. Predicting Cerebral Hyperperfusion Syndrome Following Superficial Temporal Artery to Middle Cerebral Artery Bypass based on Intraoperative Perfusion-Weighted Magnetic Resonance Imaging.

    PubMed

    Wang, Defeng; Zhu, Fengping; Fung, Ka Ming; Zhu, Wei; Luo, Yishan; Chu, Winnie Chiu Wing; Mok, Vincent Chung Tong; Wu, Jinsong; Shi, Lin; Ahuja, Anil T; Mao, Ying

    2015-09-14

    Moyamoya disease leads to the formation of stenosis in the cerebrovasculature. A superficial temporal artery to middle cerebral artery (STA-MCA) bypass is an effective treatment for the disease, yet it is usually associated with postoperative cerebral hyperperfusion syndrome (CHS). This study aimed to evaluate cerebral hemodynamic changes immediately after surgery and assess whether a semiquantitative analysis of an intraoperative magnetic resonance perfusion-weighted image (PWI) is useful for predicting postoperative CHS. Fourteen patients who underwent the STA-MCA bypass surgery were included in this study. An atlas-based registration method was employed for studying hemodynamics in different cerebral regions. Pre- versus intraoperative and group-wise comparisons were conducted to evaluate the hemodynamic changes. A postoperative increase in relative cerebral blood flow (CBF) at the terminal MCA territory (P = 0.035) and drop in relative mean-time-transit at the central MCA territory (P = 0.012) were observed in all patients. However, a significant raise in the increasing ratio of relative-CBF at the terminal MCA territory was only found in CHS patients (P = 0.023). The cerebrovascular changes of the patients after revascularization treatment were confirmed. Intraoperative PWI might be helpful in predicting the change in relative-CBF at MCA terminal territory which might indicate a risk of CHS.

  12. Robust dynamic myocardial perfusion CT deconvolution for accurate residue function estimation via adaptive-weighted tensor total variation regularization: a preclinical study

    NASA Astrophysics Data System (ADS)

    Zeng, Dong; Gong, Changfei; Bian, Zhaoying; Huang, Jing; Zhang, Xinyu; Zhang, Hua; Lu, Lijun; Niu, Shanzhou; Zhang, Zhang; Liang, Zhengrong; Feng, Qianjin; Chen, Wufan; Ma, Jianhua

    2016-11-01

    Dynamic myocardial perfusion computed tomography (MPCT) is a promising technique for quick diagnosis and risk stratification of coronary artery disease. However, one major drawback of dynamic MPCT imaging is the heavy radiation dose to patients due to its dynamic image acquisition protocol. In this work, to address this issue, we present a robust dynamic MPCT deconvolution algorithm via adaptive-weighted tensor total variation (AwTTV) regularization for accurate residue function estimation with low-mA s data acquisitions. For simplicity, the presented method is termed ‘MPD-AwTTV’. More specifically, the gains of the AwTTV regularization over the original tensor total variation regularization are from the anisotropic edge property of the sequential MPCT images. To minimize the associative objective function we propose an efficient iterative optimization strategy with fast convergence rate in the framework of an iterative shrinkage/thresholding algorithm. We validate and evaluate the presented algorithm using both digital XCAT phantom and preclinical porcine data. The preliminary experimental results have demonstrated that the presented MPD-AwTTV deconvolution algorithm can achieve remarkable gains in noise-induced artifact suppression, edge detail preservation, and accurate flow-scaled residue function and MPHM estimation as compared with the other existing deconvolution algorithms in digital phantom studies, and similar gains can be obtained in the porcine data experiment.

  13. Interictal diffusion and perfusion magnetic resonance imaging features of cats with familial spontaneous epilepsy.

    PubMed

    Mizoguchi, Shunta; Hasegawa, Daisuke; Hamamoto, Yuji; Yu, Yoshihiko; Kuwabara, Takayuki; Fujiwara-Igarashi, Aki; Fujita, Michio

    2017-03-01

    OBJECTIVE To evaluate the usefulness of diffusion and perfusion MRI of the cerebrum in cats with familial spontaneous epilepsy (FSECs) and identify microstructural and functional deficit zones in affected cats. ANIMALS 19 FSECs and 12 healthy cats. PROCEDURES Diffusion-weighted, diffusion tensor, and perfusion-weighted MRI of the cerebrum were performed during interictal periods in FSECs. Imaging findings were compared between FSECs and control cats. Diffusion (apparent diffusion coefficient and fractional anisotropy) and perfusion (relative cerebral blood volume [rCBV], relative cerebral blood flow [rCBF], and mean transit time) variables were measured bilaterally in the hippocampus, amygdala, thalamus, parietal cortex gray matter, and subcortical white matter. Asymmetry of these variables in each region was also evaluated and compared between FSECs and control cats. RESULTS The apparent diffusion coefficient of the total amygdala of FSECs was significantly higher, compared with that of control cats. The fractional anisotropy of the right side and total hippocampus of FSECs was significantly lower, compared with that of control cats. The left and right sides and total hippocampal rCBV and rCBF were significantly lower in FSECs than in control cats. The rCBV and rCBF of the parietal cortex gray matter in FSECs were significantly lower than in control cats. CONCLUSIONS AND CLINICAL RELEVANCE In FSECs, diffusion and perfusion MRI detected microstructural changes and hypoperfusion (lowered function) in the cerebrum during interictal periods from that of healthy cats. These findings indicated that diffusion and perfusion MRI may be useful for noninvasive evaluation of epileptogenic foci in cats.

  14. 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

  15. Can T2-weighted 3-T breast MRI predict clinically occult inflammatory breast cancer before pathological examination? A single-center experience.

    PubMed

    Uematsu, Takayoshi; Kasami, Masako; Watanabe, Junichiro

    2014-01-01

    Occult inflammatory breast cancer (IBC) is defined as an invasive cancer without any clinical inflammatory signs but with pathologically proven dermal lymphovascular invasion. The purpose of this study is to evaluate the ability of 3-T breast MRI to predict occult IBC before pathological examination and compare its effectiveness with that of mammography (MMG) and ultrasound (US). A retrospective review of clinical, radiological, and pathological records of 460 consecutive breast cancers revealed five proved occult IBCs. We analyzed the findings of 3-T MRI, MMG, and US for these five occult IBCs. Primary breast lesions were detected by 3-T MRI, MMG, and US in all five breasts with occult IBCs. 3-T MRI revealed 40% mass type lesions and 60% non-mass-like type lesions. Kinetic curve analysis of the primary breast lesions showed a rapid initial kinetic phase in 80% of lesions and a delayed washout pattern in 60% of lesions. 3-T MRI showed slight skin thickness in 60% of breasts, whereas MMG and US showed slight skin thickness in 40 and 20% of breasts, respectively. Subcutaneous and prepectoral edema, as evaluated on T2-weighted images, was present in all five breasts with occult IBCs. The presence of subcutaneous and prepectoral edema on T2-weighted 3-T breast MRI is an important finding that should suggest the diagnosis of occult IBC before pathological examination.

  16. Euclidian distance-weighted smoothing for quantitative MRI: application to intervoxel anisotropy index mapping with DTI

    NASA Astrophysics Data System (ADS)

    Bonny, Jean-Marie; Renou, Jean-Pierre

    2002-12-01

    During the computation of intervoxel anisotropy features, the inclusion of both eigenvalues and eigenvectors reduces the effect of noise, but spatial averaging blurs the resulting maps. We propose a new adaptive technique that uses data-dependent weights in the averaging process so that the influence of each neighbor in the local window is proportional to the similarity of characteristics of the neighbor considered to those of the reference central voxel. This likeness criterion is based on the multidimensional Euclidian distance using the entire available multispectral information contained in the diffusion-weighted images. This solution is controlled by a single parameter β that results from a compromise between edge-preserving and noise-smoothing abilities. This Euclidian distance-weighted technique is a generic solution for filtering noise during parametric reconstruction. It was applied to map anisotropy using an intervoxel lattice index (LI) from experimental images of mouse brain in vivo and achieves noise reduction without distorting small anatomical structures. We also show how to employ in the discrimination scheme the images not used in the estimation of the considered feature.

  17. Changes in T2-weighted MRI of supinator muscle, pronator teres muscle, and extensor indicis muscle with manual muscle testing

    PubMed Central

    Yoshida, Kazuya; Akiyama, Sumikazu; Takamori, Masayoshi; Otsuka, D. Eng, Hiroshi; Seo, Yoshiteru

    2017-01-01

    [Purpose] In order to detect muscle activity with manual muscle testing, T2-weighted magnetic resonance (T2w-MR) images were detected by a 0.2 T compact MRI system. [Subjects and Methods] The subjects were 3 adult males. Transverse T2-weighted multi-slice spin-echo images of the left forearm were measured by a 39 ms echo-time with a 2,000 ms repetition time, a 9.5 mm slice thickness, 1 accumulation and a total image acquisition time of 4 min 16 s. First, T2w-MR images in the resting condition were measured. Then, manipulative isometric contraction exercise (5 sec duration) to the supinator muscle, the pronator teres muscle or the extensor indicis muscle was performed using Borg’s rating of perceived exertion (RPE) scale of 15–17. The T2w-MR images were measured immediately after the exercise. [Results] T2w-MR image intensities increased significantly in the supinator muscle, the pronator teres muscle and the extensor indicis muscle after the exercise. However, the image intensities in the rest of the muscle did not change. [Conclusion] Using T2w-MR images, we could detect muscle activity in a deep muscle, the supinator muscle, and a small muscle, the extensor indicis muscle. These results also support the reliability of the manual muscle testing method. PMID:28356621

  18. Prostate segmentation in MRI using fused T2-weighted and elastography images

    NASA Astrophysics Data System (ADS)

    Nir, Guy; Sahebjavaher, Ramin S.; Baghani, Ali; Sinkus, Ralph; Salcudean, Septimiu E.

    2014-03-01

    Segmentation of the prostate in medical imaging is a challenging and important task for surgical planning and delivery of prostate cancer treatment. Automatic prostate segmentation can improve speed, reproducibility and consistency of the process. In this work, we propose a method for automatic segmentation of the prostate in magnetic resonance elastography (MRE) images. The method utilizes the complementary property of the elastogram and the corresponding T2-weighted image, which are obtained from the phase and magnitude components of the imaging signal, respectively. It follows a variational approach to propagate an active contour model based on the combination of region statistics in the elastogram and the edge map of the T2-weighted image. The method is fast and does not require prior shape information. The proposed algorithm is tested on 35 clinical image pairs from five MRE data sets, and is evaluated in comparison with manual contouring. The mean absolute distance between the automatic and manual contours is 1.8mm, with a maximum distance of 5.6mm. The relative area error is 7.6%, and the duration of the segmentation process is 2s per slice.

  19. Evaluation of Treatment Associated Inflammatory Response on Diffusion Weighted-MRI and FDG-PET Imaging Biomarkers

    PubMed Central

    Galbán, Craig J.; Bhojani, Mahaveer S; Lee, Kuei C.; Meyer, Charles R.; Van Dort, Marcian; Kuszpit, Kyle; Koeppe, Robert A.; Ranga, Rajesh; Moffat, Bradford A.; Johnson, Timothy D.; Chenevert, Thomas L.; Rehemtulla, Alnawaz; Ross, Brian D.

    2010-01-01

    Purpose Functional imaging biomarkers of cancer treatment response offer the potential for early determination of outcome through assessment of biochemical, physiological, and micro-environmental readouts. Cell death may result in an immunological response thus complicating interpretation of biomarker readouts. This study evaluated the temporal impact of treatment-associated inflammatory activity on diffusion-MRI and FDG-PET imaging biomarkers to delineate the effects of the inflammatory response on imaging readouts. Experimental Design Rats with intracerebral 9L gliosarcomas were separated into four groups consisting of control, an immunosuppressive agent dexamethasone (Dex), 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), and BCNU+Dex (BCNU+Dex). Animals were imaged using diffusion-weighted MRI and FDG-PET at 0, 3 and 7 days post-treatment. Results In the BCNU and BCNU+Dex treated animal groups, diffusion values increased progressively over the 7 day study period to about 23% over baseline. FDG %SUV decreased at day 3 (−30.9%) but increased over baseline levels at day 7 (+20.1%). FDG-PET of BCNU+Dex treated animals were found to have %SUV reductions of −31.4% and −24.7% at days 3 and 7, respectively following treatment. Activated macrophages were observed on day 7 in the BCNU treatment group with much fewer found in the BCNU+Dex group. Conclusions Results revealed treatment-associated inflammatory response following tumor therapy resulted in accentuation of tumor diffusion response along with a corresponding increase in tumor FDG uptake due to the presence of glucose-consuming activated macrophages. The dynamics and magnitude of potential inflammatory response should be considered when interpreting imaging biomarker results. PMID:20160061

  20. 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

  1. 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

  2. Cardiovascular magnetic resonance in patients with magnetic resonance conditional pacemaker systems at 1.5 T: influence of pacemaker related artifacts on image quality including first pass perfusion, aortic and mitral valve assessment, flow measurement, short tau inversion recovery and T1-weighted imaging.

    PubMed

    Klein-Wiele, Oliver; Garmer, Marietta; Busch, Martin; Mateiescu, Serban; Urbien, Rhyan; Barbone, Gianluca; Kara, Kaffer; Schulte-Hermes, Michael; Metz, Frauke; Hailer, Birgit; Grönemeyer, Dietrich

    2017-03-01

    There are only limited data on the impact of device-related artifacts on image quality in cardiovascular magnetic resonance imaging (CMR) in patients with pacemakers (PM). Adenosine stress perfusion, T1-weighted imaging and flow measurement as well as valve characterization have not been evaluated previously concerning artifact burden. We aimed to assess image quality in all routinely used CMR sequences. We analyzed 2623 myocardial segments in CMR scans of 61 patients with MR conditional PM (mean age 72.1 ± 11.5 years), 23 (37.7%) with right sided, 38 (62.3%) with left-sided devices. There were no relevant artifacts in patients with right-sided devices irrespective of the imaging sequence. In left-sided implants no PM-induced artifacts were found in first pass perfusion sequence, flow analysis and T1 weighted imaging. Only few patients with left-sided devices showed significant PM-artifacts in aortic (3/38, 7.9%)/mitral (n = 2/38, 5.3%) valve imaging and STIR (n = 3/35, 8.6%). In STIR only 14/805 (1.7%) segments were involved. In left-sided PM SSFP cine sequences had more artifact burden than LGE with 377/1505 (25.0%) vs. 162/1505 (10.8%) myocardial segments involved by relevant artifacts respectively (p < 0.001). Apart from cine and LGE imaging in anterior myocardial segments with left-sided implants presence of MRI conditional pacemakers does not affect CMR image quality in multimodal CMR examinations to a significant extent. Our data supports evidence that reduced image quality does not need to be a major concern in PM patients undergoing CMR.

  3. A review of technical aspects of T1-weighted dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in human brain tumors.

    PubMed

    Bergamino, M; Bonzano, L; Levrero, F; Mancardi, G L; Roccatagliata, L

    2014-09-01

    In the last few years, several imaging methods, such as magnetic resonance imaging (MRI) and computed tomography, have been used to investigate the degree of blood-brain barrier (BBB) permeability in patients with neurological diseases including multiple sclerosis, ischemic stroke, and brain tumors. One promising MRI method for assessing the BBB permeability of patients with neurological diseases in vivo is T1-weighted dynamic contrast-enhanced (DCE)-MRI. Here we review the technical issues involved in DCE-MRI in the study of human brain tumors. In the first part of this paper, theoretical models for the DCE-MRI analysis will be described, including the Toft-Kety models, the adiabatic approximation to the tissue homogeneity model and the two-compartment exchange model. These models can be used to estimate important kinetic parameters related to BBB permeability. In the second part of this paper, details of the data acquisition, issues related to the arterial input function, and procedures for DCE-MRI image analysis are illustrated.

  4. Visualising inter-subject variability in fMRI using threshold-weighted overlap maps

    NASA Astrophysics Data System (ADS)

    Seghier, Mohamed L.; Price, Cathy J.

    2016-02-01

    Functional neuroimaging studies are revealing the neural systems sustaining many sensory, motor and cognitive abilities. A proper understanding of these systems requires an appreciation of the degree to which they vary across subjects. Some sources of inter-subject variability might be easy to measure (demographics, behavioural scores, or experimental factors), while others are more difficult (cognitive strategies, learning effects, and other hidden sources). Here, we introduce a simple way of visualising whole-brain consistency and variability in brain responses across subjects using threshold-weighted voxel-based overlap maps. The output quantifies the proportion of subjects activating a particular voxel or region over a wide range of statistical thresholds. The sensitivity of our approach was assessed in 30 healthy adults performing a matching task with their dominant hand. We show how overlap maps revealed many effects that were only present in a subsample of our group; we discuss how overlap maps can provide information that may be missed or misrepresented by standard group analysis, and how this information can help users to understand their data. In particular, we emphasize that functional overlap maps can be particularly useful when it comes to explaining typical (or atypical) compensatory mechanisms used by patients following brain damage.

  5. Visualising inter-subject variability in fMRI using threshold-weighted overlap maps

    PubMed Central

    Seghier, Mohamed L.; Price, Cathy J.

    2016-01-01

    Functional neuroimaging studies are revealing the neural systems sustaining many sensory, motor and cognitive abilities. A proper understanding of these systems requires an appreciation of the degree to which they vary across subjects. Some sources of inter-subject variability might be easy to measure (demographics, behavioural scores, or experimental factors), while others are more difficult (cognitive strategies, learning effects, and other hidden sources). Here, we introduce a simple way of visualising whole-brain consistency and variability in brain responses across subjects using threshold-weighted voxel-based overlap maps. The output quantifies the proportion of subjects activating a particular voxel or region over a wide range of statistical thresholds. The sensitivity of our approach was assessed in 30 healthy adults performing a matching task with their dominant hand. We show how overlap maps revealed many effects that were only present in a subsample of our group; we discuss how overlap maps can provide information that may be missed or misrepresented by standard group analysis, and how this information can help users to understand their data. In particular, we emphasize that functional overlap maps can be particularly useful when it comes to explaining typical (or atypical) compensatory mechanisms used by patients following brain damage. PMID:26846561

  6. 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

  7. Arterial spin labeling perfusion predicts longitudinal decline in semantic variant primary progressive aphasia.

    PubMed

    Olm, Christopher A; Kandel, Benjamin M; Avants, Brian B; Detre, John A; Gee, James C; Grossman, Murray; McMillan, Corey T

    2016-10-01

    The objective of the study was to evaluate the prognostic value of regional cerebral blood flow (CBF) measured by arterial spin labeled (ASL) perfusion MRI in patients with semantic variant primary progressive aphasia (svPPA). We acquired pseudo-continuous ASL (pCASL) MRI and whole-brain T1-weighted structural MRI in svPPA patients (N = 13) with cerebrospinal fluid biomarkers consistent with frontotemporal lobar degeneration pathology. Follow-up T1-weighted MRI was available in a subset of patients (N = 8). We performed whole-brain comparisons of partial volume-corrected CBF and cortical thickness between svPPA and controls, and compared baseline and follow-up cortical thickness in regions of significant hypoperfusion and hyperperfusion. Patients with svPPA showed partial volume-corrected hypoperfusion relative to controls in left temporal lobe and insula. svPPA patients also had typical cortical thinning in anterior temporal, insula, and inferior frontal regions at baseline. Volume-corrected hypoperfusion was seen in areas of significant cortical thinning such as the left temporal lobe and insula. Additional regions of hypoperfusion corresponded to areas without cortical thinning. We also observed regions of hyperperfusion, some associated with cortical thinning and others without cortical thinning, including right superior temporal, inferior parietal, and orbitofrontal cortices. Regions of hypoperfusion and hyperperfusion near cortical thinning at baseline had significant longitudinal thinning between baseline and follow-up scans, but perfusion changes in distant areas did not show progressive thinning. Our findings suggest ASL MRI may be sensitive to functional changes not readily apparent in structural MRI, and specific changes in perfusion may be prognostic markers of disease progression in a manner consistent with cell-to-cell spreading pathology.

  8. Mapping Human Cortical Areas in vivo Based on Myelin Content as Revealed by T1- and T2-weighted MRI

    PubMed Central

    Glasser, Matthew F.; Van Essen, David C.

    2011-01-01

    Non-invasively mapping the layout of cortical areas in humans is a continuing challenge for neuroscience. We present a new method of mapping cortical areas based on myelin content as revealed by T1-weighted (T1w) and T2-weighted (T2w) MRI. The method is generalizable across different 3T scanners and pulse sequences. We use the ratio of T1w/T2w image intensities to eliminate the MR-related image intensity bias and enhance the contrast to noise ratio for myelin. Data from each subject was mapped to the cortical surface and aligned across individuals using surface-based registration. The spatial gradient of the group average myelin map provides an observer-independent measure of sharp transitions in myelin content across the surface—i.e. putative cortical areal borders. We found excellent agreement between the gradients of the myelin maps and the gradients of published probabilistic cytoarchitectonically defined cortical areas that were registered to the same surface-based atlas. For other cortical regions, we used published anatomical and functional information to make putative identifications of dozens of cortical areas or candidate areas. In general, primary and early unimodal association cortices are heavily myelinated and higher, multi-modal, association cortices are more lightly myelinated, but there are notable exceptions in the literature that are confirmed by our results. The overall pattern in the myelin maps also has important correlations with the developmental onset of subcortical white matter myelination, evolutionary cortical areal expansion in humans compared to macaques, postnatal cortical expansion in humans, and maps of neuronal density in non-human primates. PMID:21832190

  9. Multimodality Functional Imaging in Radiation Therapy Planning: Relationships between Dynamic Contrast-Enhanced MRI, Diffusion-Weighted MRI, and 18F-FDG PET

    PubMed Central

    Mera Iglesias, Moisés; Aramburu Núñez, David; del Olmo Claudio, José Luis; Salvador Gómez, Francisco; Driscoll, Brandon; Coolens, Catherine; Alba Castro, José L.; Muñoz, Victor

    2015-01-01

    Objectives. Biologically guided radiotherapy needs an understanding of how different functional imaging techniques interact and link together. We analyse three functional imaging techniques that can be useful tools for achieving this objective. Materials and Methods. The three different imaging modalities from one selected patient are ADC maps, DCE-MRI, and 18F-FDG PET/CT, because they are widely used and give a great amount of complementary information. We show the relationship between these three datasets and evaluate them as markers for tumour response or hypoxia marker. Thus, vascularization measured using DCE-MRI parameters can determine tumour hypoxia, and ADC maps can be used for evaluating tumour response. Results. ADC and DCE-MRI include information from 18F-FDG, as glucose metabolism is associated with hypoxia and tumour cell density, although 18F-FDG includes more information about the malignancy of the tumour. The main disadvantage of ADC maps is the distortion, and we used only low distorted regions, and extracellular volume calculated from DCE-MRI can be considered equivalent to ADC in well-vascularized areas. Conclusion. A dataset for achieving the biologically guided radiotherapy must include a tumour density study and a hypoxia marker. This information can be achieved using only MRI data or only PET/CT studies or mixing both datasets. PMID:25788972

  10. T1-weighted in vivo human whole brain MRI dataset with an ultrahigh isotropic resolution of 250 μm

    PubMed Central

    Lüsebrink, Falk; Sciarra, Alessandro; Mattern, Hendrik; Yakupov, Renat; Speck, Oliver

    2017-01-01

    We present an ultrahigh resolution in vivo human brain magnetic resonance imaging (MRI) dataset. It consists of T1-weighted whole brain anatomical data acquired at 7 Tesla with a nominal isotropic resolution of 250 μm of a single young healthy Caucasian subject and was recorded using prospective motion correction. The raw data amounts to approximately 1.2 TB and was acquired in eight hours total scan time. The resolution of this dataset is far beyond any previously published in vivo structural whole brain dataset. Its potential use is to build an in vivo MR brain atlas. Methods for image reconstruction and image restoration can be improved as the raw data is made available. Pre-processing and segmentation procedures can possibly be enhanced for high magnetic field strength and ultrahigh resolution data. Furthermore, potential resolution induced changes in quantitative data analysis can be assessed, e.g., cortical thickness or volumetric measures, as high quality images with an isotropic resolution of 1 and 0.5 mm of the same subject are included in the repository as well. PMID:28291265

  11. Applicable apparent diffusion coefficient of an orthotopic mouse model of gastric cancer by improved clinical MRI diffusion weighted imaging

    PubMed Central

    Sun, Jia; Zhang, Xiao-Peng; Li, Xiao-Ting; Tang, Lei; Cui, Yong; Zhang, Xiao-Yan; Sun, Ying-Shi

    2014-01-01

    In vivo imaging studies in animal models are hindered by variables that contribute to poor image quality and measurement reliability. As such we sought to improve the diffusion coefficient (ADC) of an orthotopic mouse model of gastric cancer in diffusion-weighted images (DWI) using alginate moulding and Ultrasonic coupling medium. BGC-823 human gastric cancer cells were subcutaneously injected into the abdomen of nude mice and 1 mm3 primary tumour was orthotopically transplanted. Alginate and coupling medium were applied to the mice and MRI (T2 and DWI) was performed for 6 weeks. Regions of interest (ROI) were drawn and liver and tumour ADC were evaluated. Using alginate moulding, the mean quality total score of DW imaging was 8.53; however, in control animals this value was 5.20 (p < 0.001). The coefficient of variation of ADC of liver in experimental and control groups were 0.071 and 0.270 (p < 0.001), respectively, suggesting this method may be helpful for DWI studies of important human diseases such as gastric cancer. PMID:25123166

  12. Case Report of False-Negative Diffusion-Weighted Image of Brain Magnetic Resonance Imaging (MRI) in Acute Ischemic Stroke

    PubMed Central

    Chang, Wei-Lun; Lai, Ji-Ching; Chen, Rong-Fu; Hu, Han-Hwa; Pan, Chau-Shiung

    2017-01-01

    Patient: Male, 75 Final Diagnosis: Acute ischemic stroke Symptoms: Dizziness • unsteady gait Medication: — Clinical Procedure: None Specialty: Radiology Objective: Challenging differential diagnosis Background: Acute ischemic stroke is a major cause of mortality and morbidity in Taiwan. Diffusion-weighted image (DWI) is a sensitive and common strategy used for imaging acute ischemic stroke. Case report: We present a case of a negative DWI MRI for detecting acute ischemic stroke in a clinical setting. A 75-year-old male had a DWI performed after onset of symptoms suggesting acute ischemic stroke. The initial DWI result was negative at 72 hours of presentation. The neurological symptoms of the patient persisted and DWI was repeated. After 14 days, the DWI data confirmed and demonstrated an acute ischemic stroke. The delay in DWI confirmation, from symptom onset until DWI diagnosis, was 336 hours. Conclusions: DWI may not have 100% sensitivity and accuracy in early stages of acute ischemic stroke. The time course to the development of abnormalities detected by DWI may be longer than anticipated. PMID:28111452

  13. Value of Perfusion-Weighted MR Imaging in the Assessment of Early Cerebral Alterations in Neurologically Asymptomatic HIV-1-Positive and HCV-Positive Patients

    PubMed Central

    Bladowska, Joanna; Knysz, Brygida; Zimny, Anna; Małyszczak, Krzysztof; Kołtowska, Anna; Szewczyk, Paweł; Gąsiorowski, Jacek; Furdal, Michał; Sąsiadek, Marek J.

    2014-01-01

    Background and Purpose Asymptomatic central nervous system (CNS) involvement occurs in the early stage of the human immunodeficiency virus (HIV) infection. It has been documented that the hepatitis C virus (HCV) can replicate in the CNS. The aim of the study was to evaluate early disturbances in cerebral microcirculation using magnetic resonance (MR) perfusion-weighted imaging (PWI) in asymptomatic HIV-1-positive and HCV-positive patients, as well as to assess the correlation between PWI measurements and the clinical data. Materials and Methods Fifty-six patients: 17 HIV-1-positive non-treated, 18 HIV-1-positive treated with combination antiretroviral therapy (cART), 7 HIV-1/HCV-positive non-treated, 14 HCV-positive before antiviral therapy and 18 control subjects were enrolled in the study. PWI was performed with a 1.5T MR unit using dynamic susceptibility contrast (DSC) method. Cerebral blood volume (CBV) measurements relative to cerebellum (rCBV) were evaluated in the posterior cingulated region (PCG), basal ganglia (BG), temporoparietal (TPC) and frontal cortices (FC), as well as in white matter of frontoparietal areas. Correlations of rCBV values with immunologic data and liver histology activity index (HAI) were analyzed. Results Significantly lower rCBV values were found in the right TPC and left FC as well as in PCG in HIV-1-positive naïve (p = 0.009; p = 0.020; p = 0.012), HIV-1 cART treated (p = 0.007; p = 0.009; p = 0.033), HIV-1/HCV-positive (p = 0.007; p = 0.027; p = 0.045) and HCV-positive patients (p = 0.010; p = 0.005; p = 0.045) compared to controls. HIV-1-positive cART treated and HIV-1/HCV-positive patients demonstrated lower rCBV values in the right FC (p = 0.009; p = 0.032, respectively) and the left TPC (p = 0.036; p = 0.005, respectively), while HCV-positive subjects revealed lower rCBV values in the left TPC region (p = 0.003). We found significantly elevated rCBV values in

  14. TU-F-CAMPUS-J-02: Evaluation of Textural Feature Extraction for Radiotherapy Response Assessment of Early Stage Breast Cancer Patients Using Diffusion Weighted MRI and Dynamic Contrast Enhanced MRI

    SciTech Connect

    Xie, Y; Wang, C; Horton, J; Chang, Z

    2015-06-15

    Purpose: To investigate the feasibility of using classic textural feature extraction in radiotherapy response assessment, we studied a unique cohort of early stage breast cancer patients with paired pre - and post-radiation Diffusion Weighted MRI (DWI-MRI) and Dynamic Contrast Enhanced MRI (DCE-MRI). Methods: 15 female patients from our prospective phase I trial evaluating preoperative radiotherapy were included in this retrospective study. Each patient received a single-fraction radiation treatment, and DWI and DCE scans were conducted before and after the radiotherapy. DWI scans were acquired using a spin-echo EPI sequence with diffusion weighting factors of b = 0 and b = 500 mm{sup 2} /s, and the apparent diffusion coefficient (ADC) maps were calculated. DCE-MRI scans were acquired using a T{sub 1}-weighted 3D SPGR sequence with a temporal resolution of about 1 minute. The contrast agent (CA) was intravenously injected with a 0.1 mmol/kg bodyweight dose at 2 ml/s. Two parameters, volume transfer constant (K{sup trans} ) and k{sub ep} were analyzed using the two-compartment Tofts kinetic model. For DCE parametric maps and ADC maps, 33 textural features were generated from the clinical target volume (CTV) in a 3D fashion using the classic gray level co-occurrence matrix (GLCOM) and gray level run length matrix (GLRLM). Wilcoxon signed-rank test was used to determine the significance of each texture feature’s change after the radiotherapy. The significance was set to 0.05 with Bonferroni correction. Results: For ADC maps calculated from DWI-MRI, 24 out of 33 CTV features changed significantly after the radiotherapy. For DCE-MRI pharmacokinetic parameters, all 33 CTV features of K{sup trans} and 33 features of k{sub ep} changed significantly. Conclusion: Initial results indicate that those significantly changed classic texture features are sensitive to radiation-induced changes and can be used for assessment of radiotherapy response in breast cancer.

  15. Detection of head and neck squamous cell carcinoma with diffusion weighted MRI after (chemo)radiotherapy: Correlation between radiologic and histopathologic findings

    SciTech Connect

    Vandecaveye, Vincent; Keyzer, Frederik de; Nuyts, Sandra; Deraedt, Karen; Dirix, Piet; Hamaekers, Pascal; Vander Poorten, Vincent; Delaere, Pierre; Hermans, Robert . E-mail: Robert.Hermans@uzleuven.be

    2007-03-15

    Purpose: To investigate the value of diffusion weighted magnetic resonance imaging (DW-MRI) in differentiating persistent or recurrent head and neck squamous cell carcinoma (HNSCC) from nontumoral postradiotherapeutic alterations. Methods and Materials: In 26 patients with suspicion of persistent or recurrent HNSCC, MRI of the head and neck was performed, including routine turbo spin-echo (TSE) sequences and an additional echo-planar DW-MRI sequence, using a large range of b-values (0-1000 s/mm{sup 2}). Apparent diffusion coefficient (ADC) maps were calculated. In the suspect areas at the primary site and in the suspect lymph nodes, signal intensity was measured on the native b0 and b1000 images and ADC values were calculated for these tissues. The same was done for surrounding irradiated normal tissue. Imaging results were correlated to histopathology. Results: Signal intensity on native b0 images was significantly lower for HNSCC than for nontumoral postradiotherapeutic tissue (p < 0.0001), resulting in a sensitivity of 66.2%, specificity of 60.8%, and accuracy of 62.4%. Signal intensity on native b1000 images was significantly higher for HNSCC than for nontumoral tissue (p < 0.0001), resulting in a sensitivity of 71.6%, specificity of 71.3%, and accuracy of 71.4%. ADC values were significantly lower for HNSCC than for nontumoral tissue (p < 0.0001), resulting in a sensitivity of 94.6%, specificity of 95.9%, and accuracy of 95.5%. When compared with computed tomography, TSE-MRI and fluorodeoxyglucose-positron emission tomography, DW-MRI yielded fewer false-positive results in persistent primary site abnormalities and in persistent adenopathies, and aided in the detection of subcentimetric nodal metastases. Conclusions: Diffusion weighted-MRI accurately differentiates persistent or recurrent HNSCC from nontumoral tissue changes after (chemo)radiotherapy.

  16. Renal perfusion scintiscan

    MedlinePlus

    Renal perfusion scintigraphy; Radionuclide renal perfusion scan; Perfusion scintiscan - renal; Scintiscan - renal perfusion ... supply the kidneys. This is a condition called renal artery stenosis. Significant renal artery stenosis may be ...

  17. Temporal Feature Extraction from DCE-MRI to Identify Poorly Perfused Subvolumes of Tumors Related to Outcomes of Radiation Therapy in Head and Neck Cancer

    PubMed Central

    You, Daekeun; Aryal, Madhava; Samuels, Stuart E.; Eisbruch, Avraham; Cao, Yue

    2017-01-01

    This study aimed to develop an automated model to extract temporal features from DCE-MRI in head-and-neck (HN) cancers to localize significant tumor subvolumes having low blood volume (LBV) for predicting local and regional failure after chemoradiation therapy. Temporal features were extracted from time-intensity curves to build classification model for differentiating voxels with LBV from those with high BV. Support vector machine (SVM) classification was trained on the extracted features for voxel classification. Subvolumes with LBV were then assembled from the classified voxels with LBV. The model was trained and validated on independent datasets created from 456 873 DCE curves. The resultant subvolumes were compared to ones derived by a 2-step method via pharmacokinetic modeling of blood volume, and evaluated for classification accuracy and volumetric similarity by DSC. The proposed model achieved an average voxel-level classification accuracy and DSC of 82% and 0.72, respectively. Also, the model showed tolerance on different acquisition parameters of DCE-MRI. The model could be directly used for outcome prediction and therapy assessment in radiation therapy of HN cancers, or even supporting boost target definition in adaptive clinical trials with further validation. The model is fully automatable, extendable, and scalable to extract temporal features of DCE-MRI in other tumors. PMID:28111634

  18. 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

  19. Comparison of unsupervised classification methods for brain tumor segmentation using multi-parametric MRI.

    PubMed

    Sauwen, N; Acou, M; Van Cauter, S; Sima, D M; Veraart, J; Maes, F; Himmelreich, U; Achten, E; Van Huffel, S

    2016-01-01

    Tumor segmentation is a particularly challenging task in high-grade gliomas (HGGs), as they are among the most heterogeneous tumors in oncology. An accurate delineation of the lesion and its main subcomponents contributes to optimal treatment planning, prognosis and follow-up. Conventional MRI (cMRI) is the imaging modality of choice for manual segmentation, and is also considered in the vast majority of automated segmentation studies. Advanced MRI modalities such as perfusion-weighted imaging (PWI), diffusion-weighted imaging (DWI) and magnetic resonance spectroscopic imaging (MRSI) have already shown their added value in tumor tissue characterization, hence there have been recent suggestions of combining different MRI modalities into a multi-parametric MRI (MP-MRI) approach for brain tumor segmentation. In this paper, we compare the performance of several unsupervised classification methods for HGG segmentation based on MP-MRI data including cMRI, DWI, MRSI and PWI. Two independent MP-MRI datasets with a different acquisition protocol were available from different hospitals. We demonstrate that a hierarchical non-negative matrix factorization variant which was previously introduced for MP-MRI tumor segmentation gives the best performance in terms of mean Dice-scores for the pathologic tissue classes on both datasets.

  20. Differentiation of pancreatic carcinoma and mass-forming focal pancreatitis: qualitative and quantitative assessment by dynamic contrast-enhanced MRI combined with diffusion-weighted imaging

    PubMed Central

    Zhang, Ting-Ting; Wang, Li; Liu, Huan-huan; Zhang, Cai-yuan; Li, Xiao-ming; Lu, Jian-ping; Wang, Deng-bin

    2017-01-01

    Differentiation between pancreatic carcinoma (PC) and mass-forming focal pancreatitis (FP) is invariably difficult. For the differential diagnosis, we qualitatively and quantitatively assessed the value of dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted imaging (DWI) in PC and FP in the present study. This study included 32 PC and 18 FP patients with histological confirmation who underwent DCE-MRI and DWI. The time-signal intensity curve (TIC) of PC and FP were classified into 5 types according to the time of reaching the peak, namely, type I, II, III, IV, and V, respectively, and two subtypes, namely, subtype-a (washout type) and subtype-b (plateau type) according to the part of the TIC profile after the peak. Moreover, the mean and relative apparent diffusion coefficient (ADC) value between PC and FP on DWI were compared. The type V TIC was only recognized in PC group (P < 0.01). Type IV b were more frequently observed in PC (P = 0.036), while type- IIa (P < 0.01), type- Ia (P = 0.037) in FP. We also found a significant difference in the mean and relative ADC value between PC and FP. The combined image set of DCE-MRI and DWI yielded an excellent sensitivity, specificity, and diagnostic accuracy (96.9%, 94.4%, and 96.0%). The TIC of DCE-MRI and ADC value of DWI for pancreatic mass were found to provide reliable information in differentiating PC from FP, and the combination of DCE-MRI and DWI can achieve a higher sensitivity, specificity, and diagnostic accuracy. PMID:27661003

  1. Critical Care Needs in Patients with Diffusion-Weighted Imaging Negative MRI after tPA - Does One Size Fit All?

    PubMed Central

    Faigle, Roland; Marsh, Elisabeth B.; Llinas, Rafael H.; Urrutia, Victor C.

    2015-01-01

    Background and Purpose Patients who receive intravenous (IV) tissue plasminogen activator (tPA) for ischemic stroke are currently monitored in an intensive care unit (ICU) or a comparable stroke unit for at least 24 hours due to the high frequency of neurological exams and vital sign checks. The present study evaluates ICU needs in patients with diffusion-weighted imaging (DWI) negative MRI after IV tPA. Methods A retrospective chart review was performed for 209 patients who received IV tPA for acute stroke. Data on stroke risk factors, physiologic parameters, stroke severity, MRI characteristics, and final diagnosis were collected. The timing and nature of ICU interventions, if needed, was recorded. Multivariable logistic regression was used to determine factors associated with subsequent ICU needs. Results Patients with cerebral infarct on MRI after tPA had over 9 times higher odds of requiring ICU care compared to patients with DWI negative MRI (OR 9.2, 95% CI 2.49–34.15). All DWI negative patients requiring ICU care did so by the end of tPA infusion (p = 0.006). Among patients with DWI negative MRI, need for ICU interventions was associated with higher NIH Stroke Scale (NIHSS) scores (p<0.001), uncontrolled hypertension (p<0.001), seizure at onset (p = 0.002), and reduced estimated glomerular filtration rate (eGFR) (p = 0.010). Conclusions Only a small number of DWI negative patients required ICU care. In patients without critical care needs by the end of thrombolysis, post-tPA MRI may be considered for triaging DWI negative patients to a less resource intense monitoring environment. PMID:26517543

  2. [Evaluation by statistical brain perfusion SPECT analysis on MRI findings, kana pick-out test and Mini-Mental State Examination results in patients with forgetfulness].

    PubMed

    Nakatsuka, Hiroki; Matsubara, Ichirou; Ohtani, Haruhiko

    2003-04-01

    The aim of this single photon emission computed tomography(SPECT) study was to determine the abnormality of the regional cerebral blood flow(rCBF) using a three-dimensional stereotactic surface projection (3 D-SSP) in 18 patients who were referred to the hospital because of forgetfulness. Two intergroup comparison by 3 D-SSP analysis was conducted based on MRI, kana pick-out test and Mini-Mental State Examination (MMSE) results. Of the MRI findings, in the brain atrophy group, rCBF was decreased in the posterior cingulate gyrus, medial temporal structure and parieto-temporal association cortex; these rCBF-decreased areas are similar to the Alzheimer disease pattern. In the group where the MMSE was normal but the kana pick-out test was abnormal, rCBF was decreased in the posterior cingulate gyrus and cinguloparietal transitional area. In the group where both the MMSE and kana pick-out test were abnormal, rCBF was decreased in the parieto-temporal association cortex, temporal cortex and medial temporal structure. These results suggest that 3 D-SSP analysis of the SPECT with MMSE and the kana pick-out test provides the possibility of early diagnosis of initial stage of Alzheimer's disease.

  3. Fetal MRI: A Technical Update with Educational Aspirations

    PubMed Central

    Gholipour, Ali; Estroff, Judith A.; Barnewolt, Carol E.; Robertson, Richard L.; Grant, P. Ellen; Gagoski, Borjan; Warfield, Simon K.; Afacan, Onur; Connolly, Susan A.; Neil, Jeffrey J.; Wolfberg, Adam; Mulkern, Robert V.

    2015-01-01

    Fetal magnetic resonance imaging (MRI) examinations have become well-established procedures at many institutions and can serve as useful adjuncts to ultrasound (US) exams when diagnostic doubts remain after US. Due to fetal motion, however, fetal MRI exams are challenging and require the MR scanner to be used in a somewhat different mode than that employed for more routine clinical studies. Herein we review the techniques most commonly used, and those that are available, for fetal MRI with an emphasis on the physics of the techniques and how to deploy them to improve success rates for fetal MRI exams. By far the most common technique employed is single-shot T2-weighted imaging due to its excellent tissue contrast and relative immunity to fetal motion. Despite the significant challenges involved, however, many of the other techniques commonly employed in conventional neuro- and body MRI such as T1 and T2*-weighted imaging, diffusion and perfusion weighted imaging, as well as spectroscopic methods remain of interest for fetal MR applications. An effort to understand the strengths and limitations of these basic methods within the context of fetal MRI is made in order to optimize their use and facilitate implementation of technical improvements for the further development of fetal MR imaging, both in acquisition and post-processing strategies. PMID:26225129

  4. Computed tomography perfusion imaging in spectacular shrinking deficit.

    PubMed

    Lee, Vivien H; John, Sayona; Mohammad, Yousef; Prabhakaran, Shyam

    2012-02-01

    Spectacular shrinking deficit (SSD) is characterized by abrupt onset of a major hemispheric stroke syndrome, followed by dramatic and rapid improvement. We retrospectively identified patients with SSD diagnosed at our institution between December 1, 2007, and June 30, 2009. We reviewed computed tomography perfusion (CTP) imaging to determine perfusion defect as a measure of initial ischemic penumbra, and magnetic resonance imaging diffusion-weighted imaging (DWI) to determine the final infarct core. Among the 472 consecutive ischemic stroke patients, 126 (27%) presented with major hemispheric ischemic stroke syndrome, defined as National Institutes of Health Stroke Scale score (NIHSS) ≥8 in the territory of the middle cerebral artery (MCA) or internal carotid artery (ICA). Out of these patients, we identified 8 SSD patients with available CTP data. In these 8 patients, the mean time to dramatic recovery was 3.4 hours (range, 0.75-7 hours), and the mean time from onset to CTP was 12.7 hours (range, 3-30 hours). All 8 patients had perfusion abnormalities in portions of the MCA territory (partial MCA territory in 5 patients and complete MCA territory in 3 patients). The mean time from onset to MRI DWI was 15.5 hours (range, 7.9-34 hours). Restricted diffusion was present in all patients in the corresponding MCA distribution. Vascular imaging revealed MCA occlusion in 2 patients. Cervical vascular imaging revealed carotid occlusion in 2 patients and high-grade carotid stenosis in 2 patients. The stroke mechanisms were cardioembolism in 2 patients, large artery in 4 patients, and unknown in 2 patients. Four patients had repeat CTP imaging available that demonstrated eventual resolution of the perfusion defect. SSD is associated with a "shrinking" clinical syndrome and a "shrinking" perfusion pattern on CTP that lags behind clinical recovery. CTP imaging corroborates that a larger territory is at risk in SSD and contributes to better understanding of SSD.

  5. Voxel-based Gaussian naïve Bayes classification of ischemic stroke lesions in individual T1-weighted MRI scans

    PubMed Central

    Griffis, Joseph C.; Allendorfer, Jane B.; Szaflarski, Jerzy P.

    2015-01-01

    Background Manual lesion delineation by an expert is the standard for lesion identification in MRI scans, but is time-consuming and can introduce subjective bias. Alternative methods often require multi-modal MRI data, user interaction, scans from a control population, and/or arbitrary statistical thresholding. New Method We present an approach for automatically identifying stroke lesions in individual T1-weighted MRI scans using naïve Bayes classification. Probabilistic tissue segmentation and image algebra were used to create feature maps encoding information about missing and abnormal tissue. Leave-one-case-out training and cross-validation was used to obtain out-of-sample predictions for each of 30 cases with left hemisphere stroke lesions. Results Our method correctly predicted lesion locations for 30/30 un-trained cases. Post-processing with smoothing (8mm FWHM) and cluster-extent thresholding (100 voxels) was found to improve performance. Comparison with Existing Method Quantitative evaluations of post-processed out-of-sample predictions on 30 cases revealed high spatial overlap (mean Dice similarity coefficient = 0.66) and volume agreement (mean percent volume difference = 28.91; Pearson’s r = 0.97) with manual lesion delineations. Conclusions Our automated approach agrees with manual tracing. It provides an alternative to automated methods that require multi-modal MRI data, additional control scans, or user interaction to achieve optimal performance. Our fully trained classifier has applications in neuroimaging and clinical contexts. PMID:26432931

  6. Is There an Additional Value of {sup 11}C-Choline PET-CT to T2-weighted MRI Images in the Localization of Intraprostatic Tumor Nodules?

    SciTech Connect

    Van den Bergh, Laura; Koole, Michel; Isebaert, Sofie; Joniau, Steven; Deroose, Christophe M.; Oyen, Raymond; Lerut, Evelyne; Budiharto, Tom; Mottaghy, Felix; Bormans, Guy; Van Poppel, Hendrik; Haustermans, Karin

    2012-08-01

    Purpose: To investigate the additional value of {sup 11}C-choline positron emission tomography (PET)-computed tomography (CT) to T2-weighted (T2w) magnetic resonance imaging (MRI) for localization of intraprostatic tumor nodules. Methods and Materials: Forty-nine prostate cancer patients underwent T2w MRI and {sup 11}C-choline PET-CT before radical prostatectomy and extended lymphadenectomy. Tumor regions were outlined on the whole-mount histopathology sections and on the T2w MR images. Tumor localization was recorded in the basal, middle, and apical part of the prostate by means of an octant grid. To analyze {sup 11}C-choline PET-CT images, the same grid was used to calculate the standardized uptake values (SUV) per octant, after rigid registration with the T2w MR images for anatomic reference. Results: In total, 1,176 octants were analyzed. Sensitivity, specificity, and accuracy of T2w MRI were 33.5%, 94.6%, and 70.2%, respectively. For {sup 11}C-choline PET-CT, the mean SUV{sub max} of malignant octants was significantly higher than the mean SUV{sub max} of benign octants (3.69 {+-} 1.29 vs. 3.06 {+-} 0.97, p < 0.0001) which was also true for mean SUV{sub mean} values (2.39 {+-} 0.77 vs. 1.94 {+-} 0.61, p < 0.0001). A positive correlation was observed between SUV{sub mean} and absolute tumor volume (Spearman r = 0.3003, p = 0.0362). No correlation was found between SUVs and prostate-specific antigen, T-stage or Gleason score. The highest accuracy (61.1%) was obtained with a SUV{sub max} cutoff of 2.70, resulting in a sensitivity of 77.4% and a specificity of 44.9%. When both modalities were combined (PET-CT or MRI positive), sensitivity levels increased as a function of SUV{sub max} but at the cost of specificity. When only considering suspect octants on {sup 11}C-choline PET-CT (SUV{sub max} {>=} 2.70) and T2w MRI, 84.7% of these segments were in agreement with the gold standard, compared with 80.5% for T2w MRI alone. Conclusions: The additional value of {sup

  7. MRI findings in aphasic status epilepticus.

    PubMed

    Toledo, Manuel; Munuera, Josep; Sueiras, Maria; Rovira, Rosa; Alvarez-Sabín, José; Rovira, Alex

    2008-08-01

    Ictal-MRI studies including diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI), and MR-angiography (MRA) in patients with aphasic status epilepticus (ASE) are lacking. In this report, we aim to describe the consequences of the ASE on DWIs and its impact on cerebral circulation. We retrospectively studied eight patients with ASE confirmed by ictal-EEG, who underwent ictal-MRI shortly after well-documented onset (mean time delay 3 h). ASE consisted in fluctuating aphasia, mostly associated with other subtle contralateral neurological signs such as hemiparesia, hemianopia, or slight clonic jerks. In MRI, six patients showed cortical temporoparietal hyperintensity in DWI and four of them had also ipsilateral pulvinar lesions. Five patients showed close spatial hyperperfusion areas matching the DWI lesions and an enhanced blow flow in the middle cerebral artery. Parenchymal lesions and hemodynamic abnormalities were not associated with seizure duration or severity in any case. The resolution of DWI lesions at follow-up MRI depended on the length of the MRIs interval. In patients with ASE, lesions on DWI in the temporo-parietal cortex and pulvinar nucleus combined with local hyperperfusion can be observed, even when they appear distant from the epileptic focus or the language areas.

  8. Three-dimensional T2-weighted MRI of the Human Femoral Arterial Vessel Wall at 3.0Tesla

    PubMed Central

    Zhang, Zhuoli; Fan, Zhaoyang; Carroll, Timothy J.; Chung, YiuCho; Weale, Peter; Jerecic, Renate; Li, Debiao

    2010-01-01

    OBJECTIVES To evaluate the potential use of a novel 3D turbo spin-echo (TSE) T2-weighted (T2w) technique for assessing the vessel wall in the superficial femoral artery at 3.0T. BACKGROUND Magnetic resonance imaging (MRI) can be used for the noninvasive assessment of atherosclerotic plaque burden in the peripheral circulation. While black-blood 2D TSE techniques have been used for femoral arterial wall imaging, these techniques require prolonged imaging time to cover a large field of view required to cover the leg. Recently, variable-flip-angle 3D TSE T2w (SPACE) has been introduced as a fast vessel wall imaging technique with submillimeter spatial resolution. A systematic investigation of the application of this technique to femoral arterial wall imaging has yet to be performed. METHODS Fifteen healthy volunteers and 3 patients with peripheral arterial disease (PAD) underwent 3D SPACE imaging of the superficial femoral artery at 3.0T, with the conventional 2D TSE T2w imaging as a reference. Muscle-lumen contrast to noise ratio (CNR) and wall/lumen volumes (WV, LV) were measured at the matched locations on the 3D and 2D image sets. Statistical comparison on a per-subject basis was conducted to determine the difference and agreement between 3D SPACE and the 2D TSE techniques. RESULTS The 3D SPACE data sets enabled vessel visualization from arbitrary orientation through multi-planar reformation (MPR) technique. Muscle-lumen CNR was significantly higher with 3D SPACE than with the 2D TSE (3.12 ± 0.84 vs. 2.17 ± 0.34, p < 0.01). This trend was confirmed when CNR efficiency (CNReff) values were further compared. A similar trend was observed in PAD patients (SPACE vs. 2D TSE T2w: CNR 2.35 ± 0.13 vs. 1.77 ± 0.25; CNReff 15.35 ± 0.61 vs. 3.59 ± 2.62. all p < 0.05). Measurements of WV and LV from the 3D and 2D techniques were highly correlated in volunteers and PAD patients (volunteers, WV: linear regression r2 = 0.98, LV: r2 = 0.98, p < 0.001 for both; patients, WV

  9. Stroke mimic: Perfusion magnetic resonance imaging of a patient with ictal paralysis

    PubMed Central

    Sanghvi, D; Goyal, C; Mani, J

    2016-01-01

    We present an uncommon case of clinically diagnosed window period stroke subsequently recognised on diffusion – perfusion MRI as ictal paralysis due to focal inhibitory seizures or negative motor seizures. This case highlights the importance of MRI with perfusion imaging in establishing the diagnosis of stroke mimics and avoiding unnecessary thrombolysis. PMID:27763486

  10. Non-parametric representation and prediction of single- and multi-shell diffusion-weighted MRI data using Gaussian processes.

    PubMed

    Andersson, Jesper L R; Sotiropoulos, Stamatios N

    2015-11-15

    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.

  11. fMRI reactivity to high-calorie food pictures predicts short- and long-term outcome in a weight-loss program.

    PubMed

    Murdaugh, Donna L; Cox, James E; Cook, Edwin W; Weller, Rosalyn E

    2012-02-01

    Behavioral studies have suggested that food cues have stronger motivating effects in obese than in normal-weight individuals, which may be a risk factor underlying obesity. Previous cross-sectional neuroimaging studies have suggested that this difference is mediated by increased reactivity to food cues in parts of the reward system in obese individuals. To date, however, only a few prospective neuroimaging studies have been conducted to examine whether individual differences in brain activation elicited by food cues can predict differences in weight change. We used functional magnetic resonance imaging (fMRI) to investigate activation in reward-system as well as other brain regions in response to viewing high-calorie food vs. control pictures in 25 obese individuals before and after a 12-week psychosocial weight-loss treatment and at 9-mo follow-up. In those obese individuals who were least successful in losing weight during the treatment, we found greater pre-treatment activation to high-calorie food vs. control pictures in brain regions implicated in reward-system processes, such as the nucleus accumbens, anterior cingulate, and insula. We found similar correlations with weight loss in brain regions implicated by other studies in vision and attention, such as superior occipital cortex, inferior and superior parietal lobule, and prefrontal cortex. Furthermore, less successful weight maintenance at 9-mo follow-up was predicted by greater post-treatment activation in such brain regions as insula, ventral tegmental area, putamen, and fusiform gyrus. In summary, we found that greater activation in brain regions mediating motivational and attentional salience of food cues in obese individuals at the start of a weight-loss program was predictive of less success in the program and that such activation following the program predicted poorer weight control over a 9-mo follow-up period.

  12. Multicentre multiobserver study of diffusion-weighted and fluid-attenuated inversion recovery MRI for the diagnosis of sporadic Creutzfeldt-Jakob disease: a reliability and agreement study.

    PubMed

    Fujita, Koji; Harada, Masafumi; Sasaki, Makoto; Yuasa, Tatsuhiko; Sakai, Kenji; Hamaguchi, Tsuyoshi; Sanjo, Nobuo; Shiga, Yusei; Satoh, Katsuya; Atarashi, Ryuichiro; Shirabe, Susumu; Nagata, Ken; Maeda, Tetsuya; Murayama, Shigeo; Izumi, Yuishin; Kaji, Ryuji; Yamada, Masahito; Mizusawa, Hidehiro

    2012-01-01

    Objectives To assess the utility of the display standardisation of diffusion-weighted MRI (DWI) and to compare the effectiveness of DWI and fluid-attenuated inversion recovery (FLAIR) MRI for the diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD). Design A reliability and agreement study. Setting Thirteen MRI observers comprising eight neurologists and five radiologists at two universities in Japan. Participants Data of 1.5-Tesla DWI and FLAIR were obtained from 29 patients with sCJD and 13 controls. Outcome measures Standardisation of DWI display was performed utilising b0 imaging. The observers participated in standardised DWI, variable DWI (the display adjustment was observer dependent) and FLAIR sessions. The observers independently assessed each MRI for CJD-related lesions, that is, hyperintensity in the cerebral cortex or striatum, using a continuous rating scale. Performance was evaluated by the area under the receiver operating characteristics curve (AUC). Results The mean AUC values were 0.84 (95% CI 0.81 to 0.87) for standardised DWI, 0.85 (95% CI 0.82 to 0.88) for variable DWI and 0.68 (95% CI 0.63 to 0.72) for FLAIR, demonstrating the superiority of DWI (p<0.05). There was a trend for higher intraclass correlations of standardised DWI (0.74, 95% CI 0.66 to 0.83) and variable DWI (0.72, 95% CI 0.62 to 0.81) than that of FLAIR (0.63, 95% CI 0.53 to 0.74), although the differences were not statistically significant. Conclusions Standardised DWI is as reliable as variable DWI, and the two DWI displays are superior to FLAIR for the diagnosis of sCJD. The authors propose that hyperintensity in the cerebral cortex or striatum on 1.5-Tesla DWI but not FLAIR can be a reliable diagnostic marker for sCJD.

  13. MRI-based quantification of Duchenne muscular dystrophy in a canine model

    NASA Astrophysics Data System (ADS)

    Wang, Jiahui; Fan, Zheng; Kornegay, Joe N.; Styner, Martin A.

    2011-03-01

    Duchenne muscular dystrophy (DMD) is a progressive and fatal X-linked disease caused by mutations in the DMD gene. Magnetic resonance imaging (MRI) has shown potential to provide non-invasive and objective biomarkers for monitoring disease progression and therapeutic effect in DMD. In this paper, we propose a semi-automated scheme to quantify MRI features of golden retriever muscular dystrophy (GRMD), a canine model of DMD. Our method was applied to a natural history data set and a hydrodynamic limb perfusion data set. The scheme is composed of three modules: pre-processing, muscle segmentation, and feature analysis. The pre-processing module includes: calculation of T2 maps, spatial registration of T2 weighted (T2WI) images, T2 weighted fat suppressed (T2FS) images, and T2 maps, and intensity calibration of T2WI and T2FS images. We then manually segment six pelvic limb muscles. For each of the segmented muscles, we finally automatically measure volume and intensity statistics of the T2FS images and T2 maps. For the natural history study, our results showed that four of six muscles in affected dogs had smaller volumes and all had higher mean intensities in T2 maps as compared to normal dogs. For the perfusion study, the muscle volumes and mean intensities in T2FS were increased in the post-perfusion MRI scans as compared to pre-perfusion MRI scans, as predicted. We conclude that our scheme successfully performs quantitative analysis of muscle MRI features of GRMD.

  14. Measurement of blood-brain barrier permeability with t1-weighted dynamic contrast-enhanced MRI in brain tumors: a comparative study with two different algorithms.

    PubMed

    Bergamino, Maurizio; Saitta, Laura; Barletta, Laura; Bonzano, Laura; Mancardi, Giovanni Luigi; Castellan, Lucio; Ravetti, Jean Louis; Roccatagliata, Luca

    2013-01-01

    The purpose of this study was to assess the feasibility of measuring different permeability parameters with T1-weighted dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in order to investigate the blood brain-barrier permeability associated with different brain tumors. The Patlak algorithm and the extended Tofts-Kety model were used to this aim. Twenty-five adult patients with tumors of different histological grades were enrolled in this study. MRI examinations were performed at 1.5 T. Multiflip angle, fast low-angle shot, and axial 3D T1-weighted images were acquired to calculate T1 maps, followed by a DCE acquisition. A region of interest was placed within the tumor of each patient to calculate the mean value of different permeability parameters. Differences in permeability measurements were found between different tumor grades, with higher histological grades characterized by higher permeability values. A significant difference in transfer constant (K (trans)) values was found between the two methods on high-grade tumors; however, both techniques revealed a significant correlation between the histological grade of tumors and their K (trans) values. Our results suggest that DCE acquisition is feasible in patients with brain tumors and that K (trans) maps can be easily obtained by these two algorithms, even if the theoretical model adopted could affect the final results.

  15. Partial volume correction of brain perfusion estimates using the inherent signal data of time-resolved arterial spin labeling.

    PubMed

    Ahlgren, André; Wirestam, Ronnie; Petersen, Esben Thade; Ståhlberg, Freddy; Knutsson, Linda

    2014-09-01

    Quantitative perfusion MRI based on arterial spin labeling (ASL) is hampered by partial volume effects (PVEs), arising due to voxel signal cross-contamination between different compartments. To address this issue, several partial volume correction (PVC) methods have been presented. Most previous methods rely on segmentation of a high-resolution T1 -weighted morphological image volume that is coregistered to the low-resolution ASL data, making the result sensitive to errors in the segmentation and coregistration. In this work, we present a methodology for partial volume estimation and correction, using only low-resolution ASL data acquired with the QUASAR sequence. The methodology consists of a T1 -based segmentation method, with no spatial priors, and a modified PVC method based on linear regression. The presented approach thus avoids prior assumptions about the spatial distribution of brain compartments, while also avoiding coregistration between different image volumes. Simulations based on a digital phantom as well as in vivo measurements in 10 volunteers were used to assess the performance of the proposed segmentation approach. The simulation results indicated that QUASAR data can be used for robust partial volume estimation, and this was confirmed by the in vivo experiments. The proposed PVC method yielded probable perfusion maps, comparable to a reference method based on segmentation of a high-resolution morphological scan. Corrected gray matter (GM) perfusion was 47% higher than uncorrected values, suggesting a significant amount of PVEs in the data. Whereas the reference method failed to completely eliminate the dependence of perfusion estimates on the volume fraction, the novel approach produced GM perfusion values independent of GM volume fraction. The intra-subject coefficient of variation of corrected perfusion values was lowest for the proposed PVC method. As shown in this work, low-resolution partial volume estimation in connection with ASL perfusion

  16. Using Dynamic Contrast Enhanced MRI to Quantitatively Characterize Maternal Vascular Organization in the Primate Placenta

    PubMed Central

    Frias, A.E.; Schabel, M.C.; Roberts, V.H.J.; Tudorica, A.; Grigsby, P.L.; Oh, K.Y.; Kroenke, C. D.

    2015-01-01

    Purpose The maternal microvasculature of the primate placenta is organized into 10-20 perfusion domains that are functionally optimized to facilitate nutrient exchange to support fetal growth. This study describes a dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) method for identifying vascular domains, and quantifying maternal blood flow in them. Methods A rhesus macaque on the 133rd day of pregnancy (G133, term=165 days) underwent Doppler ultrasound (US) procedures, DCE-MRI, and Cesarean-section delivery. Serial T1-weighted images acquired throughout intravenous injection of a contrast reagent (CR) bolus were analyzed to obtain CR arrival time maps of the placenta. Results Watershed segmentation of the arrival time map identified 16 perfusion domains. The number and location of these domains corresponded to anatomical cotyledonary units observed following delivery. Analysis of the CR wave front through each perfusion domain enabled determination of volumetric flow, which ranged from 9.03 to 44.9 mL/sec (25.2 ± 10.3 mL/sec). These estimates are supported by Doppler US results. Conclusions The DCE-MRI analysis described here provides quantitative estimates of the number of maternal perfusion domains in a primate placenta, and estimates flow within each domain. Anticipated extensions of this technique are to the study placental function in nonhuman primate models of obstetric complications. PMID:24753177

  17. 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.

  18. [CT perfusion for assessment of brain stem ischemic lesions].

    PubMed

    Saifullina, E I; Iksanova, G R

    2007-01-01

    Modern neurovisualization modalities - CT and MRI with cerebral circulation assessment was used for diagnosis of cerebrovascular disturbances in patients admitted to the Emergency Care Hospital of Ufa. CT and MRI perfusion methods appeared to be highly effective both in diagnosis and treatment efficacy monitoring of acute stroke.

  19. Comparing consistency of R2* and T2*-weighted BOLD analysis of resting state fetal fMRI

    NASA Astrophysics Data System (ADS)

    Seshamani, Sharmishtaa; Blazejewska, Anna I.; Gatenby, Christopher; Mckown, Susan; Caucutt, Jason; Dighe, Manjiri; Studholme, Colin

    2015-03-01

    Understanding when and how resting state brain functional activity begins in the human brain is an increasing area of interest in both basic neuroscience and in the clinical evaluation of the brain during pregnancy and after premature birth. Although fMRI studies have been carried out on pregnant women since the 1990's, reliable mapping of brain function in utero is an extremely challenging problem due to the unconstrained fetal head motion. Recent studies have employed scrubbing to exclude parts of the time series and whole subjects from studies in order to control the confounds of motion. Fundamentally, even after correction of the location of signals due to motion, signal intensity variations are a fundamental limitation, due to coil sensitivity and spin history effects. An alternative technique is to use a more parametric MRI signal derived from multiple echoes that provides a level of independence from basic MRI signal variation. Here we examine the use of R2* mapping combined with slice based multi echo geometric distortion correction for in-utero studies. The challenges for R2* mapping arise from the relatively low signal strength of in-utero data. In this paper we focus on comparing activation detection in-utero using T2W and R2* approaches. We make use a subset of studies with relatively limited motion to compare the activation patterns without the additional confound of significant motion. Results at different gestational ages indicate comparable agreement in many activation patterns when limited motion is present, and the detection of some additional networks in the R2* data, not seen in the T2W results.

  20. Imaging features in conventional MRI, spectroscopy and diffusion weighted images of hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS).

    PubMed

    Bender, Benjamin; Klose, Uwe; Lindig, Tobias; Biskup, Saskia; Nägele, Thomas; Schöls, Ludger; Karle, Kathrin N

    2014-12-01

    Hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) is a rare autosomal dominant disease caused by mutations within the colony stimulating factor 1 receptor (CSF1R) gene. While a small number of reports on imaging findings in routine MRI exist, reported imaging findings in DWI and spectroscopy are scarce, and limited to not genetically proven case reports. We assessed MRI including DWI and MR spectroscopy in six patients with HDLS and two asymptomatic mutation carriers. A total of 13 MRIs were evaluated and a score of the white-matter lesion (WML) load was calculated. The course of MR abnormalities was followed for 6-19 months in four patients and 95 months in one carrier. MRI revealed widespread white-matter lesions of patchy or confluent pattern especially in the frontal and occipital lobe. The pyramidal tract was less affected than the surrounding tissue in all symptomatic patients on conventional T2WI. Three of four cases with DWI showed small dots of diffusion restriction within WML. Spectroscopy showed increased levels of mIns, Cho and lactate while NAA was decreased. Asymptomatic mutation carriers had, for the age of the patients, unusually pronounced unspecific WMLs. No diffusion restriction or alterations in metabolite levels could be detected in asymptomatic mutation carriers. Microbleeds were not found in any patient. Diffusion restriction seems to be a typical imaging pattern visible in patients with active disease progression in HDLS. Spectroscopic findings and the absence of microbleeds differ clearly from reported findings in CADASIL and subcortical arteriosclerotic encephalopathy. While the distribution and character of WMLs in asymptomatic cases remain unspecific they are likely to represent subclinical markers of HDLS.

  1. Mastication induces long-term increases in blood perfusion of the trigeminal principal nucleus.

    PubMed

    Viggiano, A; Manara, R; Conforti, R; Paccone, A; Secondulfo, C; Lorusso, L; Sbordone, L; Di Salle, F; Monda, M; Tedeschi, G; Esposito, F

    2015-12-17

    Understanding mechanisms for vessel tone regulation within the trigeminal nuclei is of great interest because some headache syndromes are due to dysregulation of such mechanisms. Previous experiments on animal models suggest that mastication may alter neuron metabolism and blood supply in these nuclei. To investigate this hypothesis in humans, arterial spin-labeling magnetic resonance imaging (MRI) was used to measure blood perfusion within the principal trigeminal nucleus (Vp) and in the dorsolateral-midbrain (DM, including the mesencephalic trigeminal nucleus) in healthy volunteers, before and immediately after a mastication exercise consisting of chewing a gum on one side of the mouth for 1 h at 1 bite/s. The side preference for masticating was evaluated with a chewing test and the volume of the masseter muscle was measured on T1-weighted MRI scans. The results demonstrated that the mastication exercise caused a perfusion increase within the Vp, but not in the DM. This change was correlated to the preference score for the side where the exercise took place. Moreover, the basal Vp perfusion was correlated to the masseter volume. These results indicate that the local vascular tone of the trigeminal nuclei can be constitutively altered by the chewing practice and by strong or sustained chewing.

  2. Heart MRI

    MedlinePlus

    Magnetic resonance imaging - cardiac; Magnetic resonance imaging - heart; Nuclear magnetic resonance - cardiac; NMR - cardiac; MRI of the heart; Cardiomyopathy - MRI; Heart failure - MRI; Congenital heart disease - MRI

  3. Sub-millimeter T2 weighted fMRI at 7 T: comparison of 3D-GRASE and 2D SE-EPI.

    PubMed

    Kemper, Valentin G; De Martino, Federico; Vu, An T; Poser, Benedikt A; Feinberg, David A; Goebel, Rainer; Yacoub, Essa

    2015-01-01

    Functional magnetic resonance imaging (fMRI) allows studying human brain function non-invasively up to the spatial resolution of cortical columns and layers. Most fMRI acquisitions rely on the blood oxygenation level dependent (BOLD) contrast employing T(*) 2 weighted 2D multi-slice echo-planar imaging (EPI). At ultra-high magnetic field (i.e., 7 T and above), it has been shown experimentally and by simulation, that T2 weighted acquisitions yield a signal that is spatially more specific to the site of neuronal activity at the cost of functional sensitivity. This study compared two T2 weighted imaging sequences, inner-volume 3D Gradient-and-Spin-Echo (3D-GRASE) and 2D Spin-Echo EPI (SE-EPI), with evaluation of their imaging point-spread function (PSF), functional specificity, and functional sensitivity at sub-millimeter resolution. Simulations and measurements of the imaging PSF revealed that the strongest anisotropic blurring in 3D-GRASE (along the second phase-encoding direction) was about 60% higher than the strongest anisotropic blurring in 2D SE-EPI (along the phase-encoding direction). In a visual paradigm, the BOLD sensitivity of 3D-GRASE was found to be superior due to its higher temporal signal-to-noise ratio (tSNR). High resolution cortical depth profiles suggested that the contrast mechanisms are similar between the two sequences, however, 2D SE-EPI had a higher surface bias owing to the higher T(*) 2 contribution of the longer in-plane EPI echo-train for full field of view compared to the reduced field of view of zoomed 3D-GRASE.

  4. Magnetic resonance imaging of luxury perfusion of the optic nerve head in anterior ischemic optic neuropathy.

    PubMed

    Yovel, Oren S; Katz, Miriam; Leiba, Hana

    2012-09-01

    A 49-year-old woman with painless reduction in visual acuity in her left eye was found to have nonarteritic anterior ischemic optic neuropathy (NAION). Fluorescein angiography revealed optic disc capillary leakage consistent with "luxury perfusion." Contrast-enhanced FLAIR magnetic resonance imaging (MRI) showed marked enhancement of the left optic disc. Resolution of the optic disc edema and the MRI abnormalities followed a similar time course. This report appears unique in documenting the MRI findings of luxury perfusion in NAION.

  5. MRI Evaluation and Safety in the Developing Brain

    PubMed Central

    Tocchio, Shannon; Kline-Fath, Beth; Kanal, Emanuel; Schmithorst, Vincent J.; Panigrahy, Ashok

    2015-01-01

    Magnetic resonance imaging (MRI) evaluation of the developing brain has dramatically increased over the last decade. Faster acquisitions and the development of advanced MRI sequences such as magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI), perfusion imaging, functional MR imaging (fMRI), and susceptibility weighted imaging (SWI), as well as the use of higher magnetic field strengths has made MRI an invaluable tool for detailed evaluation of the developing brain. This article will provide an overview of the use and challenges associated with 1.5T and 3T static magnetic fields for evaluation of the developing brain. This review will also summarize the advantages, clinical challenges and safety concerns specifically related to MRI in the fetus and newborn, including the implications of increased magnetic field strength, logistics related to transporting and monitoring of neonates during scanning, sedation considerations and a discussion of current technologies such as MRI-conditional neonatal incubators and dedicated small-foot print neonatal intensive care unit (NICU) scanners. PMID:25743582

  6. Comparison of non-Gaussian and Gaussian diffusion models of diffusion weighted imaging of rectal cancer at 3.0 T MRI

    PubMed Central

    Zhang, Guangwen; Wang, Shuangshuang; Wen, Didi; Zhang, Jing; Wei, Xiaocheng; Ma, Wanling; Zhao, Weiwei; Wang, Mian; Wu, Guosheng; Zhang, Jinsong

    2016-01-01

    Water molecular diffusion in vivo tissue is much more complicated. We aimed to compare non-Gaussian diffusion models of diffusion-weighted imaging (DWI) including intra-voxel incoherent motion (IVIM), stretched-exponential model (SEM) and Gaussian diffusion model at 3.0 T MRI in patients with rectal cancer, and to determine the optimal model for investigating the water diffusion properties and characterization of rectal carcinoma. Fifty-nine consecutive patients with pathologically confirmed rectal adenocarcinoma underwent DWI with 16 b-values at a 3.0 T MRI system. DWI signals were fitted to the mono-exponential and non-Gaussian diffusion models (IVIM-mono, IVIM-bi and SEM) on primary tumor and adjacent normal rectal tissue. Parameters of standard apparent diffusion coefficient (ADC), slow- and fast-ADC, fraction of fast ADC (f), α value and distributed diffusion coefficient (DDC) were generated and compared between the tumor and normal tissues. The SEM exhibited the best fitting results of actual DWI signal in rectal cancer and the normal rectal wall (R2 = 0.998, 0.999 respectively). The DDC achieved relatively high area under the curve (AUC = 0.980) in differentiating tumor from normal rectal wall. Non-Gaussian diffusion models could assess tissue properties more accurately than the ADC derived Gaussian diffusion model. SEM may be used as a potential optimal model for characterization of rectal cancer. PMID:27934928

  7. Evaluation of efficacy of transcatheter arterial chemoembolization combined with computed tomography-guided radiofrequency ablation for hepatocellular carcinoma using magnetic resonance diffusion weighted imaging and computed tomography perfusion imaging

    PubMed Central

    Shao, Guo-Liang; Zheng, Jia-Ping; Guo, Li-Wen; Chen, Yu-Tang; Zeng, Hui; Yao, Zheng

    2017-01-01

    Abstract Background: The purpose of this study is to evaluate the efficacy of transcatheter arterial chemoembolization (TACE) combined with computed tomography-guided radiofrequency ablation (CT-RFA) in the treatment of hepatocellular carcinoma (HCC) using magnetic resonance diffusion weighted imaging (MR-DWI) and CT perfusion imaging (CT-PI). Methods: From January 2008 to January 2014, a total of 522 HCC patients receiving TACE combined with CT-RFA were included in this study. All patients underwent TACE followed by CT-RFA, and 1 day before treatment and 1 month after treatment they received MR-DWI and CT-PI. Enzyme-linked immunosorbent assay (ELISA) was performed to detect the concentration of alpha-fetoprotein (AFP). Tumor response was evaluated using the revised RECIST criteria. One-year follow-up was conducted on all patients. Receiver-operating characteristic (ROC) curve was drawn to evaluate the efficacy of TACE combined with CT-RFA for HCC using MR-DWI and CT-PI. Results: Total effective rate (complete remission [CR] + partial remission [PR]) of TACE combined with CT-RFA for HCC was 82.95%. HCC patients of CR + PR had lower hepatic blood flow (HBF), hepatic blood volume (HBV), permeability surface (PS), hepatic arterial perfusion (HAP), and hepatic perfusion index (HPI) levels than those of SD + PD, but HCC patients of CR + PR had higher mean transit time (MTT) level than those of SD + PD. The patients of PR + CR had higher apparent diffusion coefficient (ADC) values than those of SD + PD. The patients of PR + CR showed lower AFP concentration than those of SD + PD. ROC curve analysis indicated that the area under the curve (AUC) of AFP, HBV, PS, HAP, HPI, and ADC was more than 0.7, but the AUC of HBF, MTT, and PVP were less than 0.7. After treatment, the AFP, HBF, HBV, PS, HAP, and HPI in the HCC patients with recurrence were higher than those in the HCC patients without, but MTT and ADC in the HCC patients with

  8. Application of contrast-enhanced T1-weighted MRI-based 3D reconstruction of the dural tail sign in meningioma resection.

    PubMed

    You, Binsheng; Cheng, Yanhao; Zhang, Jian; Song, Qimin; Dai, Chao; Heng, Xueyuan; Fei, Chang

    2016-07-01

    OBJECT The goal of this study was to investigate the significance of contrast-enhanced T1-weighted (T1W) MRI-based 3D reconstruction of dural tail sign (DTS) in meningioma resection. METHODS Between May 2013 and August 2014, 18 cases of convexity and parasagittal meningiomas showing DTS on contrast-enhanced T1W MRI were selected. Contrast-enhanced T1W MRI-based 3D reconstruction of DTS was conducted before surgical treatment. The vertical and anteroposterior diameters of DTS on the contrast-enhanced T1W MR images and 3D reconstruction images were measured and compared. Surgical incisions were designed by referring to the 3D reconstruction and MR images, and then the efficiency of the 2 methods was evaluated with assistance of neuronavigation. RESULTS Three-dimensional reconstruction of DTS can reveal its overall picture. In most cases, the DTS around the tumor is uneven, whereas the DTS around the dural vessels presents longer extensions. There was no significant difference (p > 0.05) between the vertical and anteroposterior diameters of DTS measured on the contrast-enhanced T1W MR and 3D reconstruction images. The 3D images of DTS were more intuitive, and the overall picture of DTS could be revealed in 1 image, which made it easier to design the incision than by using the MR images. Meanwhile, assessment showed that the incisions designed using 3D images were more accurate than those designed using MR images (ridit analysis by SAS, F = 7.95; p = 0.008). Pathological examination showed that 34 dural specimens (except 2 specimens from 1 tumor) displayed tumor invasion. The distance of tumor cell invasion was 1.0-21.6 mm (5.4 ± 4.41 mm [mean ± SD]). Tumor cell invasion was not observed at the dural resection margin in all 36 specimens. CONCLUSIONS Contrast-enhanced T1W MRI-based 3D reconstruction can intuitively and accurately reveal the size and shape of DTS, and thus provides guidance for designing meningioma incisions.

  9. Imaging of myocardial perfusion with magnetic resonance.

    PubMed

    Barkhausen, Jörg; Hunold, Peter; Jochims, Markus; Debatin, Jörg F

    2004-06-01

    Coronary artery disease (CAD) is currently the leading cause of death in developed nations. Reflecting the complexity of cardiac function and morphology, noninvasive diagnosis of CAD represents a major challenge for medical imaging. Although coronary artery stenoses can be depicted with magnetic resonance (MR) and computed tomography (CT) techniques, its functional or hemodynamic impact frequently remains elusive. Therefore, there is growing interest in other, target organ-specific parameters such as myocardial function at stress and first-pass myocardial perfusion imaging to assess myocardial blood flow. This review explores the pathophysiologic background, recent technical developments, and current clinical status of first-pass MR imaging (MRI) of myocardial perfusion.

  10. Functional Imaging: CT and MRI

    PubMed Central

    van Beek, Edwin JR; Hoffman, Eric A

    2008-01-01

    Synopsis Numerous imaging techniques permit evaluation of regional pulmonary function. Contrast-enhanced CT methods now allow assessment of vasculature and lung perfusion. Techniques using spirometric controlled MDCT allow for quantification of presence and distribution of parenchymal and airway pathology, Xenon gas can be employed to assess regional ventilation of the lungs and rapid bolus injections of iodinated contrast agent can provide quantitative measure of regional parenchymal perfusion. Advances in magnetic resonance imaging (MRI) of the lung include gadolinium-enhanced perfusion imaging and hyperpolarized helium imaging, which can allow imaging of pulmonary ventilation and .measurement of the size of emphysematous spaces. PMID:18267192

  11. Head MRI

    MedlinePlus

    ... the head; MRI - cranial; NMR - cranial; Cranial MRI; Brain MRI; MRI - brain; MRI - head ... the test, tell your provider if you have: Brain aneurysm clips An artificial heart valves Heart defibrillator ...

  12. 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

    Ng, Shu-Hang; Lin, Chien-Yu; 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.

  13. 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.

  14. 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

    2016-08-07

    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.

  15. The Predictive Value of Early Assessment After 1 Cycle of Induction Chemotherapy with 18F-FDG PET/CT and Diffusion-Weighted MRI for Response to Radical Chemoradiotherapy in Head and Neck Squamous Cell Carcinoma.

    PubMed

    Wong, Kee H; Panek, Rafal; Welsh, Liam; Mcquaid, Dualta; Dunlop, Alex; Riddell, Angela; Murray, Iain; Du, Yong; Chua, Sue; Koh, Dow-Mu; Bhide, Shreerang; Nutting, Chris; Oyen, Wim J G; Harrington, Kevin; Newbold, Kate L

    2016-12-01

    The objective of this study was to assess the predictive value of early assessment (after 1 cycle of induction chemotherapy [IC]) with (18)F-FDG PET/CT and diffusion-weighted (DW) MRI for subsequent response to radical chemoradiotherapy in locally advanced head and neck squamous cell carcinoma (HNSCC).

  16. Breast MRI at Very Short TE (minTE): Image Analysis of minTE Sequences on Non-Fat-Saturated, Subtracted T1-Weighted Images.

    PubMed

    Wenkel, Evelyn; Janka, Rolf; Geppert, Christian; Kaemmerer, Nadine; Hartmann, Arndt; Uder, Michael; Hammon, Matthias; Brand, Michael

    2017-02-01

    resolution for a better in-flow curve.. · Dynamic breast MRI with a shorter TE time is possible without relevant loss of information.. · Possible decrease of the overall scan time.. Citation Format · Wenkel E, Janka R, Geppert C et al. Breast MRI at Very Short TE (minTE): Image Analysis of minTE Sequences on Non-Fat-Saturated, Subtracted T1-Weighted Images. Fortschr Röntgenstr 2017; 189: 137 - 145.

  17. A case of mass-forming splenic tuberculosis: MRI findings with emphasis of diffusion-weighted imaging characteristics.

    PubMed

    Lim, Jihe; Yu, Jeong-Sik; Hong, Soon Won; Chung, Jae-Joon; Kim, Joo Hee; Kim, Ki Whang

    2011-03-01

    Tuberculosis remains one of the most prevalent and fatal infectious diseases in spite of considerable improvements in medical science. The diagnosis and treatment of extrapulmonary tuberculosis involving the abdomen is still complicated owing to vague or non-specific clinical features. Although rare, isolated splenic involvement is one of the important manifestations of extrapulmonary tuberculosis, and imaging suspicion of the disease is essential. We report a case of surgically confirmed mass-forming splenic tuberculosis showing a layered pattern consisting of caseous necrosis with profound restriction of water molecules surrounded by an irregular rind of granulation tissue with less diffusion restriction on diffusion-weighted magnetic resonance imaging (DWI). In the differential diagnosis of neoplastic or non-neoplastic mass-forming lesions involving the spleen, this unique DWI feature could be helpful in characterizing splenic tuberculosis. The patient has been in clinically disease free status for nearly 20 months after splenectomy.

  18. Is there more valuable information in PWI datasets for a voxel-wise acute ischemic stroke tissue outcome prediction than what is represented by typical perfusion maps?

    NASA Astrophysics Data System (ADS)

    Forkert, Nils Daniel; Siemonsen, Susanne; Dalski, Michael; Verleger, Tobias; Kemmling, Andre; Fiehler, Jens

    2014-03-01

    The acute ischemic stroke is a leading cause for death and disability in the industry nations. In case of a present acute ischemic stroke, the prediction of the future tissue outcome is of high interest for the clinicians as it can be used to support therapy decision making. Within this context, it has already been shown that the voxel-wise multi-parametric tissue outcome prediction leads to more promising results compared to single channel perfusion map thresholding. Most previously published multi-parametric predictions employ information from perfusion maps derived from perfusion-weighted MRI together with other image sequences such as diffusion-weighted MRI. However, it remains unclear if the typically calculated perfusion maps used for this purpose really include all valuable information from the PWI dataset for an optimal tissue outcome prediction. To investigate this problem in more detail, two different methods to predict tissue outcome using a k-nearest-neighbor approach were developed in this work and evaluated based on 18 datasets of acute stroke patients with known tissue outcome. The first method integrates apparent diffusion coefficient and perfusion parameter (Tmax, MTT, CBV, CBF) information for the voxel-wise prediction, while the second method employs also apparent diffusion coefficient information but the complete perfusion information in terms of the voxel-wise residue functions instead of the perfusion parameter maps for the voxel-wise prediction. Overall, the comparison of the results of the two prediction methods for the 18 patients using a leave-one-out cross validation revealed no considerable differences. Quantitatively, the parameter-based prediction of tissue outcome led to a mean Dice coefficient of 0.474, while the prediction using the residue functions led to a mean Dice coefficient of 0.461. Thus, it may be concluded from the results of this study that the perfusion parameter maps typically derived from PWI datasets include all

  19. The performance of MR perfusion-weighted imaging for the differentiation of high-grade glioma from primary central nervous system lymphoma: A systematic review and meta-analysis

    PubMed Central

    Xu, Bainan

    2017-01-01

    It is always a great challenge to distinguish high-grade glioma (HGG) from primary central nervous system lymphoma (PCNSL). We conducted a meta-analysis to assess the performance of MR perfusion-weighted imaging (PWI) in differentiating HGG from PCNSL. The heterogeneity and threshold effect were evaluated, and the sensitivity (SEN), specificity (SPE) and areas under summary receiver operating characteristic curve (SROC) were calculated. Fourteen studies with a total of 598 participants were included in this meta-analysis. The results indicated that PWI had a high level of accuracy (area under the curve (AUC) = 0.9415) for differentiating HGG from PCNSL by using the best parameter from each study. The dynamic susceptibility-contrast (DSC) technique might be an optimal index for distinguishing HGGs from PCNSLs (AUC = 0.9812). Furthermore, the DSC had the best sensitivity 0.963 (95%CI: 0.924, 0.986), whereas the arterial spin-labeling (ASL) displayed the best specificity 0.896 (95% CI: 0.781, 0.963) among those techniques. However, the variability of the optimal thresholds from the included studies suggests that further evaluation and standardization are needed before the techniques can be extensively clinically used. PMID:28301491

  20. Contribution of diffusion weighted MRI to diagnosis and staging in gastric tumors and comparison with multi-detector computed tomography

    PubMed Central

    Fatih Özbay, Mehmet; Çallı, İskan; Doğan, Erkan; Çelik, Sebahattin; Batur, Abdussamet; Bora, Aydın; Yavuz, Alpaslan; Bulut, Mehmet Deniz; Özgökçe, Mesut; Çetin Kotan, Mehmet

    2017-01-01

    Abstract Background Diagnostic performance of Diffusion-Weighted magnetic resonance Imaging (DWI) and Multi-Detector Computed Tomography (MDCT) for TNM (Tumor, Lymph node, Metastasis) staging of gastric cancer was compared. Patients and methods We used axial T2-weighted images and DWI (b-0,400 and b-800 s/mm2) protocol on 51 pre-operative patients who had been diagnosed with gastric cancer. We also conducted MDCT examinations on them. We looked for a signal increase in the series of DWI images. The depth of tumor invasion in the stomach wall (tumor (T) staging), the involvement of lymph nodes (nodal (N) staging), and the presence or absence of metastases (metastatic staging) in DWI and CT images according to the TNM staging system were evaluated. In each diagnosis of the tumors, sensitivity, specificity, positive and negative accuracy rates of DWI and MDCT examinations were found through a comparison with the results of the surgical pathology, which is the gold standard method. In addition to the compatibilities of each examination with surgical pathology, kappa statistics were used. Results Sensitivity and specificity of DWI and MDCT in lymph node staging were as follows: N1: DWI: 75.0%, 84.6%; MDCT: 66.7%, 82%;N2: DWI: 79.3%, 77.3%; MDCT: 69.0%, 68.2%; N3: DWI: 60.0%, 97.6%; MDCT: 50.0%, 90.2%. The diagnostic tool DWI seemed more compatible with the gold standard method (surgical pathology), especially in the staging of lymph node, when compared to MDCT. On the other hand, in T staging, the results of DWI and MDCT were better than the gold standard when the T stage increased. However, DWI did not demonstrate superiority to MDCT. The sensitivity and specificity of both imaging techniques for detecting distant metastasis were 100%. Conclusions The diagnostic accuracy of DWI for TNM staging in gastric cancer before surgery is at a comparable level with MDCT and adding DWI to routine protocol of evaluating lymph nodes metastasis might increase diagnostic accuracy

  1. 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

  2. The Impact of Diffusion-Weighted MRI on the Definition of Gross Tumor Volume in Radiotherapy of Non-Small-Cell Lung Cancer

    PubMed Central

    Fleckenstein, Jochen; Jelden, Michael; Kremp, Stephanie; Jagoda, Philippe; Stroeder, Jonas; Khreish, Fadi; Ezziddin, Samer; Buecker, Arno; Rübe, Christian; Schneider, Guenther K.

    2016-01-01

    Objective The study was designed to evaluate diffusion-weighted magnetic resonance imaging (DWI) vs. PET-CT of the thorax in the determination of gross tumor volume (GTV) in radiotherapy planning of non-small-cell lung cancer (NSCLC). Materials and Methods Eligible patients with NSCLC who were supposed to receive definitive radio(chemo)therapy were prospectively recruited. For MRI, a respiratory gated T2-weighted sequence in axial orientation and non-gated DWI (b = 0, 800, 1,400 and apparent diffusion coefficient map [ADC]) were acquired on a 1.5 Tesla scanner. Primary tumors were delineated on FDG-PET/CT (stGTV) and DWI images (dwGTV). The definition of stGTV was based on the CT and visually adapted to the FDG-PET component if indicated (e.g., in atelectasis). For DWI, dwGTV was visually determined and adjusted for anatomical plausibility on T2w sequences. Beside a statistical comparison of stGTV and dwGTB, spatial agreement was determined with the “Hausdorff-Distance” (HD) and the “Dice Similarity Coefficient” (DSC). Results Fifteen patients (one patient with two synchronous NSCLC) were evaluated. For 16 primary tumors with UICC stages I (n = 4), II (n = 3), IIIA (n = 2) and IIIB (n = 7) mean values for dwGTV were significantly larger than those of stGTV (76.6 ± 84.5 ml vs. 66.6 ± 75.2 ml, p<0.01). The correlation of stGTV and dwGTV was highly significant (r = 0.995, p<0.001). Yet, some considerable volume deviations between these two methods were observed (median 27.5%, range 0.4–52.1%). An acceptable agreement between dwGTV and stGTV regarding the spatial extent of primary tumors was found (average HD: 2.25 ± 0.7 mm; DC 0.68 ± 0.09). Conclusion The overall level of agreement between PET-CT and MRI based GTV definition is acceptable. Tumor volumes may differ considerably in single cases. DWI-derived GTVs are significantly, yet modestly, larger than their PET-CT based counterparts. Prospective studies to assess the safety and efficacy of DWI

  3. 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

  4. Task-based evaluation of segmentation algorithms for diffusion-weighted MRI without using a gold standard.

    PubMed

    Jha, Abhinav K; Kupinski, Matthew A; Rodríguez, Jeffrey J; Stephen, Renu M; Stopeck, Alison T

    2012-07-07

    In many studies, the estimation of the apparent diffusion coefficient (ADC) of lesions in visceral organs in diffusion-weighted (DW) magnetic resonance images requires an accurate lesion-segmentation algorithm. To evaluate these lesion-segmentation algorithms, region-overlap measures are used currently. However, the end task from the DW images is accurate ADC estimation, and the region-overlap measures do not evaluate the segmentation algorithms on this task. Moreover, these measures rely on the existence of gold-standard segmentation of the lesion, which is typically unavailable. In this paper, we study the problem of task-based evaluation of segmentation algorithms in DW imaging in the absence of a gold standard. We first show that using manual segmentations instead of gold-standard segmentations for this task-based evaluation is unreliable. We then propose a method to compare the segmentation algorithms that does not require gold-standard or manual segmentation results. The no-gold-standard method estimates the bias and the variance of the error between the true ADC values and the ADC values estimated using the automated segmentation algorithm. The method can be used to rank the segmentation algorithms on the basis of both the ensemble mean square error and precision. We also propose consistency checks for this evaluation technique.

  5. [Examination of upper abdominal region in high spatial resolution diffusion-weighted imaging using 3-Tesla MRI].

    PubMed

    Terada, Masaki; Matsushita, Hiroki; Oosugi, Masanori; Inoue, Kazuyasu; Yaegashi, Taku; Anma, Takeshi

    2009-03-20

    The advantage of the higher signal-to-noise ratio (SNR) of 3-Tesla magnetic resonance imaging (3-Tesla) has the possibility of contributing to the improvement of high spatial resolution without causing image deterioration. In this study, we compared SNR and the apparent diffusion coefficient (ADC) value with 3-Tesla as the condition in the diffusion-weighted image (DWI) parameter of the 1.5-Tesla magnetic resonance imaging (1.5-Tesla) and we examined the high spatial resolution images in the imaging method [respiratory-triggering (RT) method and breath free (BF) method] and artifact (motion and zebra) in the upper abdominal region of DWI at 3-Tesla. We have optimized scan parameters based on phantom and in vivo study. As a result, 3-Tesla was able to obtain about 1.5 times SNR in comparison with the 1.5-Tesla, ADC value had few differences. Moreover, the RT method was effective in correcting the influence of respiratory movement in comparison with the BF method, and image improvement by the effective acquisition of SNR and reduction of the artifact were provided. Thus, DWI of upper abdominal region was a useful sequence for the high spatial resolution in 3-Tesla.

  6. Modern imaging of the infarct core and the ischemic penumbra in acute stroke patients: CT versus MRI.

    PubMed

    Ledezma, Carlos J; Fiebach, Jochen B; Wintermark, Max

    2009-04-01

    Thrombolysis has become an approved therapy for acute stroke. However, many stroke patients do not benefit from such treatment, since the presently used criteria are very restrictive, notably with respect to the accepted time window. Even so, a significant rate of intracranial hemorrhage still occurs. Conventional cerebral computed tomography (CT) without contrast has been proposed as a selection tool for acute stroke patients. However, more-modern MRI and CT techniques, referred to as diffusion- and perfusion-weighted imaging and perfusion-CT, have been introduced, which afford a comprehensive noninvasive survey of acute stroke patients as soon as their emergency admission, with accurate demonstration of the site of arterial occlusion and its hemodynamic and pathophysiological repercussions for the brain parenchyma. The objective of this article is to present the advantages and drawbacks of CT and MRI in the evaluation of acute stroke patients.

  7. Basic concepts of advanced MRI techniques.

    PubMed

    Pagani, Elisabetta; Bizzi, Alberto; Di Salle, Francesco; De Stefano, Nicola; Filippi, Massimo

    2008-10-01

    An overview is given of magnetic resonance (MR) techniques sensitized to diffusion, flow, magnetization transfer effect, and local field inhomogeneities induced by physiological changes, that can be viewed, in the clinical practice, as advanced because of their challenging implementation and interpretation. These techniques are known as diffusion-weighted, perfusion, magnetization transfer, functional MRI and MR spectroscopy. An important issue is that they can provide quantitative estimates of structural and functional characteristics that are below the voxel resolution. This review does not deal with the basic concepts of the MR physics and the description of the available acquisition and postprocessing methods, but hopefully provides an adequate background to readers and hence facilitate the understanding of the following clinical contributions.

  8. Short-term reproducibility of apparent diffusion coefficient estimated from diffusion-weighted MRI of the prostate

    PubMed Central

    Sadinski, Meredith; Medved, Milica; Karademir, Ibrahim; Wang, Shiyang; Peng, Yahui; Jiang, Yulei; Sammet, Steffen; Karczmar, Gregory; Oto, Aytekin

    2015-01-01

    Purpose The purpose of the study is to determine short-term reproducibility of apparent diffusion coefficient (ADC) estimated from diffusion-weighted magnetic resonance (DW-MR) imaging of the prostate. Methods Fourteen patients with biopsy-proven prostate cancer were studied under an Institutional Review Board-approved protocol. Each patient underwent two, consecutive and identical DW-MR scans on a 3T system. ADC values were calculated from each scan and a deformable registration was performed to align corresponding images. The prostate and cancerous regions of interest (ROIs) were independently analyzed by two radiologists. The prostate volume was analyzed by sextant. Per-voxel absolute and relative percentage variations in ADC were compared between sextants. Per-voxel and per-ROI variations in ADC were calculated for cancerous ROIs. Results Per-voxel absolute difference in ADC in the prostate ranged from 0 to 1.60 × 10−3 mm2/s (per-voxel relative difference 0% to 200%, mean 10.5%). Variation in ADC was largest in the posterior apex (0% to 200%, mean 11.6%). Difference in ADC variation between sextants was not statistically significant. Cancer ROIs’ per-voxel variation in ADC ranged from 0.001 × 10−3 to 0.841 × 10−3 mm2/s (0% to 67.4%, mean 11.2%) and per-ROI variation ranged from 0 to 0.463 × 10−3 mm2/s (mean 0.122 × 10−3 mm2/s). Conclusions Variation in ADC within the human prostate is reasonably small, and is on the order of 10%. PMID:25805558

  9. SU-E-I-36: A KWIC and Dirty Look at Dose Savings and Perfusion Metrics in Simulated CT Neuro Perfusion Exams

    SciTech Connect

    Hoffman, J; Martin, T; Young, S; McNitt-Gray, M; Wang, D

    2015-06-15

    Purpose: CT neuro perfusion scans are one of the highest dose exams. Methods to reduce dose include decreasing the number of projections acquired per gantry rotation, however conventional reconstruction of such scans leads to sampling artifacts. In this study we investigated a projection view-sharing reconstruction algorithm used in dynamic MRI – “K-space Weighted Image Contrast” (KWIC) – applied to simulated perfusion exams and evaluated dose savings and impacts on perfusion metrics. Methods: A FORBILD head phantom containing simulated time-varying objects was developed and a set of parallel-beam CT projection data was created. The simulated scans were 60 seconds long, 1152 projections per turn, with a rotation time of one second. No noise was simulated. 5mm, 10mm, and 50mm objects were modeled in the brain. A baseline, “full dose” simulation used all projections and reduced dose cases were simulated by downsampling the number of projections per turn from 1152 to 576 (50% dose), 288 (25% dose), and 144 (12.5% dose). KWIC was further evaluated at 72 projections per rotation (6.25%). One image per second was reconstructed using filtered backprojection (FBP) and KWIC. KWIC reconstructions utilized view cores of 36, 72, 144, and 288 views and 16, 8, 4, and 2 subapertures respectively. From the reconstructed images, time-to-peak (TTP), cerebral blood flow (CBF) and the FWHM of the perfusion curve were calculated and compared against reference values from the full-dose FBP data. Results: TTP, CBF, and the FWHM were unaffected by dose reduction (to 12.5%) and reconstruction method, however image quality was improved when using KWIC. Conclusion: This pilot study suggests that KWIC preserves image quality and perfusion metrics when under-sampling projections and that the unique contrast weighting of KWIC could provided substantial dose-savings for perfusion CT scans. Evaluation of KWIC in clinical CT data will be performed in the near future. R01 EB014922, NCI

  10. T2-weighted MRI of the uterus: fast spin echo vs. breath-hold fast spin echo.

    PubMed

    Ascher, S M; O'Malley, J; Semelka, R C; Patt, R H; Rajan, S; Thomasson, D

    1999-03-01

    This study compared one routine T2-weighted fast spin echo (T2FSE) sequence with a breath-hold T2FSE (BH T2FSE) sequence of the female pelvis for image quality, uterine anatomy, lesion detection, and signal intensity measurements. Thirty-two consecutive women (mean age 41.7 years) were imaged at 1.5 T with one high-resolution routine T2FSE sequence and one BH T2FSE sequence in the sagittal plane as part of comprehensive pelvic magnetic resonance imaging. The different image sets were rated separately for imaging characteristics (overall image quality, uterine anatomy definition, lesion detection, and free fluid conspicuity) and then compared side by side. The image sets were also compared for artifacts (ghosting, blurring, pulsatility, and chemical shift misregistration). Signal-to-noise (S/N) and signal difference-to-noise (SD/N) ratios were calculated for the different uterine zones, uterine abnormalities, free fluid, rectus abdominis muscle, and bladder. Contrast-to-noise ratios (CNRs) were calculated for uterine abnormalities. Twenty-eight uterine abnormalities were detected in 20 patients and included leiomyomata (13 patients), adenomyosis (7 patients), benign endometrial polyps (6 patients), endometrial carcinoma (1 patient), and pregnancy (1 patient). BH T2FSE was superior or equivalent to T2FSE for overall image quality in 23/32 patients (71.8%), uterine anatomy definition in 19/32 patients (59.3%), and lesion detection in 13/20 patients (65%). BH T2FSE performed less well than T2FSE for free fluid conspicuity in 5/5 (100%) patients. BH T2FSE was equivalent to or less affected than T2FSE for ghosting artifact in 24/32 patients (75%) and blurring artifact in 29/32 patients (90.6%). Pulsatility and chemical shift artifacts were not problematic for either image set. S/N and SD/N were higher for all BH T2FSE determinations compared with T2FSE. For the endometrium, junctional zone, myometrium, and bladder, these differences were statistically significant. There

  11. Feasibility study on energy prediction of microwave ablation upon uterine adenomyosis and leiomyomas by MRI

    PubMed Central

    Xia, M; Zhi-yu, H; Jian-ming, C; Hong-yu, Z; Rui-fang, X; Yu, Y; Yan-li, H; Bao-wei, D

    2014-01-01

    Objective: To evaluate the feasibility of energy prediction of percutaneous microwave ablation (PMWA) upon uterine leiomyomas and adenomyosis by MRI. Methods: 63 patients (49 patients with 49 uterine leiomyomas and 14 patients with adenomyosis) who underwent ultrasound-guided PMWA treatment were studied during the period from June 2011 to December 2012. Before PMWA, contrast-enhanced MRI (ceMRI) was performed for all of the patients. Based on the signal intensity (SI) of T2 weighted MRI, uterine leiomyomas were classified as hypointense, isointense and hyperintense. During ablation, the output energy of the microwave was set at 50 W, and T11a microwave antennas were used. ceMRI was performed within 7 days after PMWA treatment. Non-perfused volume and energy required per unit volume were analysed statistically. Results: When unit volume of lesions was ablated, uterine adenomyosis needed more energy than did uterine leiomyomas, and hyperintense uterine leiomyomas needed more energy than did hypointense pattern. Conclusions: MRI SI of uterine leiomyomas and uterine adenomyosis can be used to predict PMWA energy. Advances in knowledge: The conclusions indicate that MRI SI can be used to perform pre-treatment planning, which will make the treatment more precise. PMID:24947033

  12. Is quantitative diffusion-weighted MRI a valuable technique for the detection of changes in kidneys after extracorporeal shock wave lithotripsy?

    PubMed Central

    Hocaoglu, Elif; Inci, Ercan; Aydin, Sibel; Cesme, Dilek Hacer; Kalfazade, Nadir

    2015-01-01

    Objective The aim of this study was to evaluate the capability and the reliability of diffusion-weighted imaging (DWI) in the changes of kidneys occurring after extracorporeal shock wave lithotripsy (ESWL) treatment for renal stones. Materials and Methods A total of 32 patients who underwent ESWL treatment for renal stone disease between June and December 2011 were enrolled in this prospective study. Color Doppler ultrasonography (CDUS) and DWI were performed before and within 24 hours after ESWL. DWI was obtained with b factors of 0, 500 and 1000 s/mm2 at 1.5 T MRI. Each of Resistive index (RI) and ADC values were calculated from the three regions of renal upper, middle and lower zones for both of the affected and contralateral kidneys. Paired sample t test was used for statistical analyses. Results After ESWL, the treated kidneys had statistically significant lower ADC values in all different regions compared with previous renal images. The best discriminative parameter was signal intensity with a b value of 1000 s/mm2. The changes of DWI after ESWL were noteworthy in the middle of the treated kidney (p<0.01). There were no significant difference between RI values in all regions of treated and contralateral kidneys before and after treatment with ESWL (p>0.05). Conclusion DWI is a valuable technique enables the detection of changes in DWI after ESWL treatment that may provide useful information in prediction of renal damage by shock waves, even CDUS is normal. PMID:25928520

  13. Assessment of non-Gaussian diffusion with singly and doubly stretched biexponential models of diffusion-weighted MRI (DWI) signal attenuation in prostate tissue.

    PubMed

    Hall, Matt G; Bongers, Andre; Sved, Paul; Watson, Geoffrey; Bourne, Roger M

    2015-04-01

    Non-Gaussian diffusion dynamics was investigated in the two distinct water populations identified by a biexponential model of diffusion in prostate tissue. Diffusion-weighted MRI (DWI) signal attenuation was measured ex vivo in two formalin-fixed prostates at 9.4 T with diffusion times Δ = 10, 20 and 40 ms, and b values in the range 0.017-8.2 ms/µm(2) . A conventional biexponential model was compared with models in which either the lower diffusivity component or both of the components of the biexponential were stretched. Models were compared using Akaike's Information Criterion (AIC) and a leave-one-out (LOO) test of model prediction accuracy. The doubly stretched (SS) model had the highest LOO prediction accuracy and lowest AIC (highest information content) in the majority of voxels at Δ = 10 and 20 ms. The lower diffusivity stretching factor (α2 ) of the SS model was consistently lower (range ~0.3-0.9) than the higher diffusivity stretching factor (α1 , range ~0.7-1.1), indicating a high degree of diffusion heterogeneity in the lower diffusivity environment, and nearly Gaussian diffusion in the higher diffusivity environment. Stretched biexponential models demonstrate that, in prostate tissue, the two distinct water populations identified by the simple biexponential model individually exhibit non-Gaussian diffusion dynamics.

  14. A robust multi-shot scan strategy for high-resolution diffusion weighted MRI enabled by multiplexed sensitivity-encoding (MUSE).

    PubMed

    Chen, Nan-Kuei; Guidon, Arnaud; Chang, Hing-Chiu; Song, Allen W

    2013-05-15

    Diffusion weighted magnetic resonance imaging (DWI) data have been mostly acquired with single-shot echo-planar imaging (EPI) to minimize motion induced artifacts. The spatial resolution, however, is inherently limited in single-shot EPI, even when the parallel imaging (usually at an acceleration factor of 2) is incorporated. Multi-shot acquisition strategies could potentially achieve higher spatial resolution and fidelity, but they are generally susceptible to motion-induced phase errors among excitations that are exacerbated by diffusion sensitizing gradients, rendering the reconstructed images unusable. It has been shown that shot-to-shot phase variations may be corrected using navigator echoes, but at the cost of imaging throughput. To address these challenges, a novel and robust multi-shot DWI technique, termed multiplexed sensitivity-encoding (MUSE), is developed here to reliably and inherently correct nonlinear shot-to-shot phase variations without the use of navigator echoes. The performance of the MUSE technique is confirmed experimentally in healthy adult volunteers on 3Tesla MRI systems. This newly developed technique should prove highly valuable for mapping brain structures and connectivities at high spatial resolution for neuroscience studies.

  15. A robust multi-shot scan strategy for high-resolution diffusion weighted MRI enabled by multiplexed sensitivity-encoding (MUSE)

    PubMed Central

    Chen, Nan-kuei; Guidon, Arnaud; Chang, Hing-Chiu; Song, Allen W.

    2013-01-01

    Diffusion weighted magnetic resonance imaging (DWI) data have been mostly acquired with single-shot echo-planar imaging (EPI) to minimize motion induced artifacts. The spatial resolution, however, is inherently limited in single-shot EPI, even when the parallel imaging (usually at an acceleration factor of 2) is incorporated. Multi-shot acquisition strategies could potentially achieve higher spatial resolution and fidelity, but they are generally susceptible to motion-induced phase errors among excitations that are exacerbated by diffusion sensitizing gradients, rendering the reconstructed images unusable. It has been shown that shot-to-shot phase variations may be corrected using navigator echoes, but at the cost of imaging throughput. To address these challenges, a novel and robust multi-shot DWI technique, termed multiplexed sensitivity-encoding (MUSE), is developed here to reliably and inherently correct nonlinear shot-to-shot phase variations without the use of navigator echoes. The performance of the MUSE technique is confirmed experimentally in healthy adult volunteers on 3 Tesla MRI systems. This newly developed technique should prove highly valuable for mapping brain structures and connectivities at high spatial resolution for neuroscience studies. PMID:23370063

  16. Evaluation of head and neck tumors with functional MRI

    PubMed Central

    Jansen, Jacobus F.A.; Parra, Carlos; Lu, Yonggang; Shukla-Dave, Amita

    2015-01-01

    Synopsys Head and neck (HN) cancer is one of the most common cancers worldwide. Magnetic Resonance Imaging (MRI) based diffusion and perfusion techniques enable the non-invasive assessment of tumor biology and physiology, which supplement information obtained from standard structural scans. Diffusion and perfusion MRI techniques provide novel biomarkers that can aid the monitoring pre-, during, and post-treatment stages to improve patient selection for therapeutic strategies, provide evidence for change of therapy regime, and evaluation of treatment response. This review discusses pertinent aspects of the role of diffusion and perfusion MRI and computational analysis methods in studying HN cancer. PMID:26613878

  17. Physiologic MRI for assessment of response to therapy and prognosis in glioblastoma

    PubMed Central

    Shiroishi, Mark S.; Boxerman, Jerrold L.; Pope, Whitney B.

    2016-01-01

    Aside from bidimensional measurements from conventional contrast-enhanced MRI, there are no validated or FDA-qualified imaging biomarkers for high-grade gliomas. However, advanced functional MRI techniques, including perfusion- and diffusion-weighted MRI, have demonstrated much potential for determining prognosis, predicting therapeutic response, and assessing early treatment response. They may also prove useful for differentiating pseudoprogression from true progression after temozolomide chemoradiation and pseudoresponse from true response after anti-angiogenic therapy. This review will highlight recent developments using these techniques and emphasize the need for technical standardization and validation in prospective studies in order for these methods to become incorporated into standard-of-care imaging for brain tumor patients. PMID:26364321

  18. Schizophrenia patients differentiation based on MR vascular perfusion and volumetric imaging

    NASA Astrophysics Data System (ADS)

    Spanier, A. B.; Joskowicz, L.; Moshel, S.; Israeli, D.

    2015-03-01

    Candecomp/Parafac Decomposition (CPD) has emerged as a framework for modeling N-way arrays (higher-order matrices). CPD is naturally well suited for the analysis of data sets comprised of observations of a function of multiple discrete indices. In this study we evaluate the prospects of using CPD for modeling MRI brain properties (i.e. brain volume and gray-level) for schizophrenia diagnosis. Taking into account that 3D imaging data consists of millions of pixels per patient, the diagnosis of a schizophrenia patient based on pixel analysis constitutes a methodological challenge (e.g. multiple comparison problem). We show that the CPD could potentially be used as a dimensionality redaction method and as a discriminator between schizophrenia patients and match control, using the gradient of pre- and post Gd-T1-weighted MRI data, which is strongly correlated with cerebral blood perfusion. Our approach was tested on 68 MRI scans: 40 first-episode schizophrenia patients and 28 matched controls. The CPD subject's scores exhibit statistically significant result (P < 0.001). In the context of diagnosing schizophrenia with MRI, the results suggest that the CPD could potentially be used to discriminate between schizophrenia patients and matched control. In addition, the CPD model suggests for brain regions that might exhibit abnormalities in schizophrenia patients for future research.

  19. Diffusion-Weighted Imaging in 3.0 Tesla Breast MRI: Diagnostic Performance and Tumor Characterization Using Small Subregions vs. Whole Tumor Regions of Interest

    PubMed Central

    Arponent, Otso; Sudah, Mazen; Masarwah, Amro; Taina, Mikko; Rautiainen, Suvi; Könönen, Mervi; Sironen, Reijo; Kosma, Veli-Matti; Sutela, Anna; Hakumäki, Juhana; Vanninen, Ritva

    2015-01-01

    Introduction Apparent diffusion coefficient (ADC) values are increasingly reported in breast MRI. As there is no standardized method for ADC measurements, we evaluated the effect of the size of region of interest (ROI) to diagnostic utility and correlation to prognostic markers of breast cancer. Methods This prospective study was approved by the Institutional Ethics Board; the need for written informed consent for the retrospective analyses of the breast MRIs was waived by the Chair of the Hospital District. We compared diagnostic accuracy of ADC measurements from whole-lesion ROIs (WL-ROIs) to small subregions (S-ROIs) showing the most restricted diffusion and evaluated correlations with prognostic factors in 112 consecutive patients (mean age 56.2±11.6 years, 137 lesions) who underwent 3.0-T breast MRI. Results Intra- and interobserver reproducibility were substantial (κ = 0.616–0.784; Intra-Class Correlation 0.589–0.831). In receiver operating characteristics analysis, differentiation between malignant and benign lesions was excellent (area under curve 0.957–0.962, cut-off ADC values for WL-ROIs: 0.87×10−3 mm2s-1; S-ROIs: 0.69×10−3 mm2s-1, P<0.001). WL-ROIs/S-ROIs achieved sensitivities of 95.7%/91.3%, specificities of 89.5%/94.7%, and overall accuracies of 89.8%/94.2%. In S-ROIs, lower ADC values correlated with presence of axillary metastases (P = 0.03), high histological grade (P = 0.006), and worsened Nottingham Prognostic Index Score (P<0.05). In both ROIs, ADC values correlated with progesterone receptors and advanced stage (P<0.01), but not with HER2, estrogen receptors, or Ki-67. Conclusions ADC values assist in breast tumor characterization. Small ROIs were more accurate than whole-lesion ROIs and more frequently associated with prognostic factors. Cut-off values differed significantly depending on measurement procedure, which should be recognized when comparing results from the literature. Instead of using a whole lesion covering ROI, a

  20. Reversible changes in diffusion- and perfusion-based imaging in cerebral venous sinus thrombosis.

    PubMed

    Lin, Ning; Wong, Andrew K; Lipinski, Lindsay J; Mokin, Maxim; Siddiqui, Adnan H

    2016-02-01

    Diffusion- and perfusion-based imaging studies are regularly used in patients with ischemic stroke. Cerebral venous sinus thrombosis (CVST) is a rare cause of stroke and is primarily treated by systemic anticoagulation. Endovascular intervention can be considered in cases of failed medical therapy, yet the prognostic value of diffusion- and perfusion-based imaging for CVST has not been clearly established. We present a patient with CVST whose abnormal findings on MRI and CT perfusion images were largely reversed after endovascular treatment.

  1. Magnetic resonance perfusion imaging in neuro-oncology

    PubMed Central

    O’Connor, James; Thompson, Gerard; Mills, Samantha

    2008-01-01

    Abstract Recent advances in magnetic resonance imaging (MRI) have seen the development of techniques that allow quantitative imaging of a number of anatomical and physiological descriptors. These techniques have been increasingly applied to cancer imaging where they can provide some insight into tumour microvascular structure and physiology. This review details technical approaches and application of quantitative MRI, focusing particularly on perfusion imaging and its role in neuro-oncology. PMID:18980870

  2. Magnetic resonance perfusion imaging in neuro-oncology.

    PubMed

    Jackson, Alan; O'Connor, James; Thompson, Gerard; Mills, Samantha

    2008-10-13

    Recent advances in magnetic resonance imaging (MRI) have seen the development of techniques that allow quantitative imaging of a number of anatomical and physiological descriptors. These techniques have been increasingly applied to cancer imaging where they can provide some insight into tumour microvascular structure and physiology. This review details technical approaches and application of quantitative MRI, focusing particularly on perfusion imaging and its role in neuro-oncology.

  3. Prediction of Liver Function by Using Magnetic Resonance-based Portal Venous Perfusion Imaging

    PubMed Central

    Cao, Yue; Wang, Hesheng; Johnson, Timothy D.; Pan, Charlie; Hussain, Hero; Balter, James M.; Normolle, Daniel; Ben-Josef, Edgar; Ten Haken, Randall K.; Lawrence, Theodore S.; Feng, Mary

    2013-01-01

    Purpose To evaluate whether liver function can be assessed globally and spatially by using volumetric dynamic contrast-enhanced magnetic resonance imaging MRI (DCE-MRI) to potentially aid in adaptive treatment planning. Methods and Materials Seventeen patients with intrahepatic cancer undergoing focal radiation therapy (RT) were enrolled in institution review board-approved prospective studies to obtain DCE-MRI (to measure regional perfusion) and indocyanine green (ICG) clearance rates (to measure overall liver function) prior to, during, and at 1 and 2 months after treatment. The volumetric distribution of portal venous perfusion in the whole liver was estimated for each scan. We assessed the correlation between mean portal venous perfusion in the nontumor volume of the liver and overall liver function measured by ICG before, during, and after RT. The dose response for regional portal venous perfusion to RT was determined using a linear mixed effects model. Results There was a significant correlation between the ICG clearance rate and mean portal venous perfusion in the functioning liver parenchyma, suggesting that portal venous perfusion could be used as a surrogate for function. Reduction in regional venous perfusion 1 month after RT was predicted by the locally accumulated biologically corrected dose at the end of RT (P<.0007). Regional portal venous perfusion measured during RT was a significant predictor for regional venous perfusion assessed 1 month after RT (P<.00001). Global hypovenous perfusion pre-RT was observed in 4 patients (3 patients with hepatocellular carcinoma and cirrhosis), 3 of whom had recovered from hypoperfusion, except in the highest dose regions, post-RT. In addition, 3 patients who had normal perfusion pre-RT had marked hypervenous perfusion or reperfusion in low-dose regions post-RT. Conclusions This study suggests that MR-based volumetric hepatic perfusion imaging may be a biomarker for spatial distribution of liver function, which

  4. Prediction of Liver Function by Using Magnetic Resonance-based Portal Venous Perfusion Imaging

    SciTech Connect

    Cao Yue; Wang Hesheng; Johnson, Timothy D.; Pan, Charlie; Hussain, Hero; Balter, James M.; Normolle, Daniel; Ben-Josef, Edgar; Ten Haken, Randall K.; Lawrence, Theodore S.; Feng, Mary

    2013-01-01

    Purpose: To evaluate whether liver function can be assessed globally and spatially by using volumetric dynamic contrast-enhanced magnetic resonance imaging MRI (DCE-MRI) to potentially aid in adaptive treatment planning. Methods and Materials: Seventeen patients with intrahepatic cancer undergoing focal radiation therapy (RT) were enrolled in institution review board-approved prospective studies to obtain DCE-MRI (to measure regional perfusion) and indocyanine green (ICG) clearance rates (to measure overall liver function) prior to, during, and at 1 and 2 months after treatment. The volumetric distribution of portal venous perfusion in the whole liver was estimated for each scan. We assessed the correlation between mean portal venous perfusion in the nontumor volume of the liver and overall liver function measured by ICG before, during, and after RT. The dose response for regional portal venous perfusion to RT was determined using a linear mixed effects model. Results: There was a significant correlation between the ICG clearance rate and mean portal venous perfusion in the functioning liver parenchyma, suggesting that portal venous perfusion could be used as a surrogate for function. Reduction in regional venous perfusion 1 month after RT was predicted by the locally accumulated biologically corrected dose at the end of RT (P<.0007). Regional portal venous perfusion measured during RT was a significant predictor for regional venous perfusion assessed 1 month after RT (P<.00001). Global hypovenous perfusion pre-RT was observed in 4 patients (3 patients with hepatocellular carcinoma and cirrhosis), 3 of whom had recovered from hypoperfusion, except in the highest dose regions, post-RT. In addition, 3 patients who had normal perfusion pre-RT had marked hypervenous perfusion or reperfusion in low-dose regions post-RT. Conclusions: This study suggests that MR-based volumetric hepatic perfusion imaging may be a biomarker for spatial distribution of liver function, which

  5. Brain Tissue Volumes and Perfusion Change with the Number of Optic Neuritis Attacks in Relapsing Neuromyelitis Optica: A Voxel-Based Correlation Study.

    PubMed

    Sánchez-Catasús, Carlos A; Cabrera-Gomez, José; Almaguer Melián, William; Giroud Benítez, José Luis; Rodríguez Rojas, Rafael; Bayard, Jorge Bosch; Galán, Lídice; Sánchez, Reinaldo Galvizu; Fuentes, Nancy Pavón; Valdes-Sosa, Pedro

    2013-01-01

    Recent neuroimaging studies show that brain abnormalities in neuromyelitis optica (NMO) are more frequent than earlier described. Yet, more research considering multiple aspects of NMO is necessary to better understand these abnormalities. A clinical feature of relapsing NMO (RNMO) is that the incremental disability is attack-related. Therefore, association between the attack-related process and neuroimaging might be expected. On the other hand, the immunopathological analysis of NMO lesions has suggested that CNS microvasculature could be an early disease target, which could alter brain perfusion. Brain tissue volume changes accompanying perfusion alteration could also be expected throughout the attack-related process. The aim of this study was to investigate in RNMO patients, by voxel-based correlation analysis, the assumed associations between regional brain white (WMV) and grey matter volumes (GMV) and/or perfusion on one side, and the number of optic neuritis (ON) attacks, myelitis attacks and/or total attacks on the other side. For this purpose, high resolution T1-weighted MRI and perfusion SPECT imaging were obtained in 15 RNMO patients. The results showed negative regional correlations of WMV, GMV and perfusion with the number of ON attacks, involving important components of the visual system, which could be relevant for the comprehension of incremental visual disability in RNMO. We also found positive regional correlation of perfusion with the number of ON attacks, mostly overlapping the brain area where the WMV showed negative correlation. This provides evidence that brain microvasculature is an early disease target and suggests that perfusion alteration could be important in the development of brain structural abnormalities in RNMO.

  6. Diffusion-weighted 19F-MRI of lung periphery: Influence of pressure and air-SF6 composition on apparent diffusion coefficients.

    PubMed

    Ruiz-Cabello, Jesús; Pérez-Sánchez, José Manuel; Pérez de Alejo, Rigoberto; Rodríguez, Ignacio; González-Mangado, Nicolás; Peces-Barba, Germán; Cortijo, Manuel

    2005-08-25

    Lung functional magnetic resonance imaging (MRI) has become a reality using different inert hyperpolarized gases, such as 3He and 129Xe, which have provided an extraordinary boost in lung imaging and has also attracted interest to other chemically inert gaseous contrast agents. In this context, we have recently demonstrated the first diffusion-weighted images using thermally polarized inhaled sulfur hexafluoride (SF6) in small animals. The aim of this study was to evaluate whether or not the diffusion coefficient of this fluorinated gas is sensitive to pulmonary structure, gas concentration and air pressure in the airways. Diffusion coefficients of SF6 (both pure and in air mixtures) measured in vitro at different pressures and 20 degrees C showed an excellent agreement with theoretical values. Measurements of diffusion coefficients were also performed in vivo and post-mortem on healthy rats, achieving satisfactory signal-to-noise ratios (SNRs), and SF6 gas was found to be in an almost completely restricted diffusion regime in the lung, i.e., the transport by molecular diffusion is delayed by collisions with barriers such as the alveolar septa. This observed low diffusivity means that this gas will be less sensitive to structural changes in the lungs than other magnetic resonance sensitive gas such as 3He, particularly at human scale. However, it is still possible that SF6 plays a role since it opens a new structural window. Thus, the interest of researchers in delimiting the important limiting technical factors that makes this process very challenging is obvious. Among them, T2 relaxation is very fast, so gradient systems with very fast switching rate and probably large radiofrequency (RF) power and high field systems will be needed for hexafluoride to be used in human studies.

  7. Coupling between resting cerebral perfusion and EEG.

    PubMed

    O'Gorman, R L; Poil, S-S; Brandeis, D; Klaver, P; Bollmann, S; Ghisleni, C; Lüchinger, R; Martin, E; Shankaranarayanan, A; Alsop, D C; Michels, L

    2013-07-01

    While several studies have investigated interactions between the electroencephalography (EEG) and functional magnetic resonance imaging BOLD signal fluctuations, less is known about the associations between EEG oscillations and baseline brain haemodynamics, and few studies have examined the link between EEG power outside the alpha band and baseline perfusion. Here we compare whole-brain arterial spin labelling perfusion MRI and EEG in a group of healthy adults (n = 16, ten females, median age: 27 years, range 21-48) during an eyes closed rest condition. Correlations emerged between perfusion and global average EEG power in low (delta: 2-4 Hz and theta: 4-7 Hz), middle (alpha: 8-13 Hz), and high (beta: 13-30 Hz and gamma: 30-45 Hz) frequency bands in both cortical and sub-cortical regions. The correlations were predominately positive in middle and high-frequency bands, and negative in delta. In addition, central alpha frequency positively correlated with perfusion in a network of brain regions associated with the modulation of attention and preparedness for external input, and central theta frequency correlated negatively with a widespread network of cortical regions. These results indicate that the coupling between average EEG power/frequency and local cerebral blood flow varies in a frequency specific manner. Our results are consistent with longstanding concepts that decreasing EEG frequencies which in general map onto decreasing levels of activation.

  8. Abdominal perfusion computed tomography.

    PubMed

    Ogul, Hayri; Bayraktutan, Ummugulsum; Kizrak, Yesim; Pirimoglu, Berhan; Yuceler, Zeynep; Sagsoz, M Erdem; Yilmaz, Omer; Aydinli, Bulent; Ozturk, Gurkan; Kantarci, Mecit

    2013-02-01

    The purpose of this article is to provide an up to date review on the spectrum of applications of perfusion computed tomography (CT) in the abdomen. New imaging techniques have been developed with the objective of obtaining a structural and functional analysis of different organs. Recently, perfusion CT has aroused the interest of many researchers who are studying the applicability of imaging modalities in the evaluation of abdominal organs and diseases. Per-fusion CT enables fast, non-invasive imaging of the tumor vascular physiology. Moreover, it can act as an in vivo biomarker of tumor-related angiogenesis.

  9. Abdominal Perfusion Computed Tomography

    PubMed Central

    Ogul, Hayri; Bayraktutan, Ummugulsum; Kizrak, Yesim; Pirimoglu, Berhan; Yuceler, Zeynep; Sagsoz, M. Erdem; Yilmaz, Omer; Aydinli, Bulent; Ozturk, Gurkan; Kantarci, Mecit

    2013-01-01

    The purpose of this article is to provide an up to date review on the spectrum of applications of perfusion computed tomography (CT) in the abdomen. New imaging techniques have been developed with the objective of obtaining a structural and functional analysis of different organs. Recently, perfusion CT has aroused the interest of many researchers who are studying the applicability of imaging modalities in the evaluation of abdominal organs and diseases. Per-fusion CT enables fast, non-invasive imaging of the tumor vascular physiology. Moreover, it can act as an in vivo biomarker of tumor-related angiogenesis. PMID:25610249

  10. Improved measurement of labile proton concentration-weighted chemical exchange rate (k(ws)) with experimental factor-compensated and T(1) -normalized quantitative chemical exchange saturation transfer (CEST) MRI.

    PubMed

    Wu, Renhua; Liu, Charng-Ming; Liu, Philip K; Sun, Phillip Zhe

    2012-01-01

    Chemical exchange saturation transfer (CEST) MRI enables measurement of dilute CEST agents and microenvironment properties such as pH and temperature, holding great promise for in vivo applications. However, because of confounding concomitant radio frequency (RF) irradiation and relaxation effects, the CEST-weighted MRI contrast may not fully characterize the underlying CEST phenomenon. We postulated that the accuracy of quantitative CEST MRI could be improved if the experimental factors (labeling efficiency and RF spillover effect) were estimated and taken into account. Specifically, the experimental factor was evaluated as a function of exchange rate and CEST agent concentration ratio, which remained relatively constant for intermediate RF irradiation power levels. Hence, the experimental factors can be calculated based on the reasonably estimated exchange rate and labile proton concentration ratio, which significantly improved quantification. The simulation was confirmed with creatine phantoms of serially varied concentration titrated to the same pH, whose reverse exchange rate (k(ws)) was found to be linearly correlated with the concentration. In summary, the proposed solution provides simplified yet reasonably accurate quantification of the underlying CEST system, which may help guide the ongoing development of quantitative CEST MRI.

  11. Perfusion Magnetic Resonance Imaging: A Comprehensive Update on Principles and Techniques

    PubMed Central

    Li, Ka-Loh; Ostergaard, Leif; Calamante, Fernando

    2014-01-01

    Perfusion is a fundamental biological function that refers to the delivery of oxygen and nutrients to tissue by means of blood flow. Perfusion MRI is sensitive to microvasculature and has been applied in a wide variety of clinical applications, including the classification of tumors, identification of stroke regions, and characterization of other diseases. Perfusion MRI techniques are classified with or without using an exogenous contrast agent. Bolus methods, with injections of a contrast agent, provide better sensitivity with higher spatial resolution, and are therefore more widely used in clinical applications. However, arterial spin-labeling methods provide a unique opportunity to measure cerebral blood flow without requiring an exogenous contrast agent and have better accuracy for quantification. Importantly, MRI-based perfusion measurements are minimally invasive overall, and do not use any radiation and radioisotopes. In this review, we describe the principles and techniques of perfusion MRI. This review summarizes comprehensive updated knowledge on the physical principles and techniques of perfusion MRI. PMID:25246817

  12. MRI and low back pain

    MedlinePlus

    Backache - MRI; Low back pain - MRI; Lumbar pain - MRI; Back strain - MRI; Lumbar radiculopathy - MRI; Herniated intervertebral disk - MRI; Prolapsed intervertebral disk - MRI; Slipped disk - MRI; Ruptured ...

  13. 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.

  14. Tumor Metabolism and Perfusion in Head and Neck Squamous Cell Carcinoma: Pretreatment Multimodality Imaging With {sup 1}H Magnetic Resonance Spectroscopy, Dynamic Contrast-Enhanced MRI, and [{sup 18}F]FDG-PET

    SciTech Connect

    Jansen, Jacobus F.A.; Schoeder, Heiko; Lee, Nancy Y.; Stambuk, Hilda E.; Wang Ya; Fury, Matthew G.; Patel, Senehal G.; Pfister, David G.; Shah, Jatin P.; Koutcher, Jason A.; Shukla-Dave, Amita

    2012-01-01

    Purpose: To correlate proton magnetic resonance spectroscopy ({sup 1}H-MRS), dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), and {sup 18}F-labeled fluorodeoxyglucose positron emission tomography ([{sup 18}F]FDG PET) of nodal metastases in patients with head and neck squamous cell carcinoma (HNSCC) for assessment of tumor biology. Additionally, pretreatment multimodality imaging was evaluated for its efficacy in predicting short-term response to treatment. Methods and Materials: Metastatic neck nodes were imaged with {sup 1}H-MRS, DCE-MRI, and [{sup 18}F]FDG PET in 16 patients with newly diagnosed HNSCC, before treatment. Short-term patient radiological response was evaluated at 3 to 4 months. Correlations among {sup 1}H-MRS (choline concentration relative to water [Cho/W]), DCE-MRI (volume transfer constant [K{sup trans}]; volume fraction of the extravascular extracellular space [v{sub e}]; and redistribution rate constant [k{sub ep}]), and [{sup 18}F]FDG PET (standard uptake value [SUV] and total lesion glycolysis [TLG]) were calculated using nonparametric Spearman rank correlation. To predict short-term responses, logistic regression analysis was performed. Results: A significant positive correlation was found between Cho/W and TLG ({rho} = 0.599; p = 0.031). Cho/W correlated negatively with heterogeneity measures of standard deviation std(v{sub e}) ({rho} = -0.691; p = 0.004) and std(k{sub ep}) ({rho} = -0.704; p = 0.003). Maximum SUV (SUVmax) values correlated strongly with MRI tumor volume ({rho} = 0.643; p = 0.007). Logistic regression indicated that std(K{sup trans}) and SUVmean were significant predictors of short-term response (p < 0.07). Conclusion: Pretreatment multimodality imaging using {sup 1}H-MRS, DCE-MRI, and [{sup 18}F]FDG PET is feasible in HNSCC patients with nodal metastases. Additionally, combined DCE-MRI and [{sup 18}F]FDG PET parameters were predictive of short-term response to treatment.

  15. Unsupervised nonlinear dimensionality reduction machine learning methods applied to multiparametric MRI in cerebral ischemia: preliminary results

    NASA Astrophysics Data System (ADS)

    Parekh, Vishwa S.; Jacobs, Jeremy R.; Jacobs, Michael A.

    2014-03-01

    The evaluation and treatment of acute cerebral ischemia requires a technique that can determine the total area of tissue at risk for infarction using diagnostic magnetic resonance imaging (MRI) sequences. Typical MRI data sets consist of T1- and T2-weighted imaging (T1WI, T2WI) along with advanced MRI parameters of diffusion-weighted imaging (DWI) and perfusion weighted imaging (PWI) methods. Each of these parameters has distinct radiological-pathological meaning. For example, DWI interrogates the movement of water in the tissue and PWI gives an estimate of the blood flow, both are critical measures during the evolution of stroke. In order to integrate these data and give an estimate of the tissue at risk or damaged; we have developed advanced machine learning methods based on unsupervised non-linear dimensionality reduction (NLDR) techniques. NLDR methods are a class of algorithms that uses mathematically defined manifolds for statistical sampling of multidimensional classes to generate a discrimination rule of guaranteed statistical accuracy and they can generate a two- or three-dimensional map, which represents the prominent structures of the data and provides an embedded image of meaningful low-dimensional structures hidden in their high-dimensional observations. In this manuscript, we develop NLDR methods on high dimensional MRI data sets of preclinical animals and clinical patients with stroke. On analyzing the performance of these methods, we observed that there was a high of similarity between multiparametric embedded images from NLDR methods and the ADC map and perfusion map. It was also observed that embedded scattergram of abnormal (infarcted or at risk) tissue can be visualized and provides a mechanism for automatic methods to delineate potential stroke volumes and early tissue at risk.

  16. [The clinical application of diffusion weighted magnetic resonance imaging to acute cerebrovascular disorders].

    PubMed

    Chu, B C; Miyasaka, K

    1998-09-01

    Diffusion is a measure of motion freedom and is a sensitive parameter to characterize the tissue at the microscopic level. The methods of measuring in vivo diffusion by magnetic resonance imaging (MRI) have been based mainly on the addition of two motion-probing gradients (MPG) to the spin echo sequence to produce signal attenuation for the spins moving at random. The resultant MR images reflect the intravoxel incoherent motions (IVIM), which contain both water molecule diffusion and perfusion in the capillary network, and can be quantified by an apparent diffusion coefficient (ADC). Diffusion weighted MRI, acquired from IVIM MR imaging by the addition of the very strong MPG predicate water diffusion and anisotropy. High signal or reduced ADC can be observed in case of the slower diffusion. The anisotropy depends upon the orientation of the subjects and the gradients. Greater signal attenuation (faster diffusion) can be observed when the relative orientation of white matter tracts to the MPG is parallel as compared to that obtained with a perpendicular alignment. This anisotropy may preclude the detection or delineation of an ischemic lesion. Diffusion tensor trace has been designated to eliminate this anisotropy effect. In ischemic animal models, low signal (fast diffusion) and high signal (slow diffusion) have been noted in the vasogenic edema and cytotoxic edema, respectively. High signal appears only in case of cerebral blood flow below 15-20 ml/100 g per minute, a value identical to the threshold of tissue at high energetic metabolism and ion homeostasis. ADC value decreases following the cerebral vessel occlusion, or remains unchanged when collateral circulation develops. It has been speculated that reduction in ADC reflects the water shift from extracellular space to intracellular space due to the membrane permeability and/or intracellular osmolality increase. These results suggest that diffusion weighted MRI correlates well with the cell metabolism, and

  17. Classifying Glioblastoma Multiforme Follow-Up Progressive vs. Responsive Forms Using Multi-Parametric MRI Features

    PubMed Central

    Ion-Mărgineanu, Adrian; Van Cauter, Sofie; Sima, Diana M.; Maes, Frederik; Sunaert, Stefan; Himmelreich, Uwe; Van Huffel, Sabine

    2017-01-01

    Purpose: The purpose of this paper is discriminating between tumor progression and response to treatment based on follow-up multi-parametric magnetic resonance imaging (MRI) data retrieved from glioblastoma multiforme (GBM) patients. Materials and Methods: Multi-parametric MRI data consisting of conventional MRI (cMRI) and advanced MRI [i.e., perfusion weighted MRI (PWI) and diffusion kurtosis MRI (DKI)] were acquired from 29 GBM patients treated with adjuvant therapy after surgery. We propose an automatic pipeline for processing advanced MRI data and extracting intensity-based histogram features and 3-D texture features using manually and semi-manually delineated regions of interest (ROIs). Classifiers are trained using a leave-one-patient-out cross validation scheme on complete MRI data. Balanced accuracy rate (BAR)–values are computed and compared between different ROIs, MR modalities, and classifiers, using non-parametric multiple comparison tests. Results: Maximum BAR–values using manual delineations are 0.956, 0.85, 0.879, and 0.932, for cMRI, PWI, DKI, and all three MRI modalities combined, respectively. Maximum BAR–values using semi-manual delineations are 0.932, 0.894, 0.885, and 0.947, for cMRI, PWI, DKI, and all three MR modalities combined, respectively. After statistical testing using Kruskal-Wallis and post-hoc Dunn-Šidák analysis we conclude that training a RUSBoost classifier on features extracted using semi-manual delineations on cMRI or on all MRI modalities combined performs best. Conclusions: We present two main conclusions: (1) using T1 post-contrast (T1pc) features extracted from manual total delineations, AdaBoost achieves the highest BAR–value, 0.956; (2) using T1pc-average, T1pc-90th percentile, and Cerebral Blood Volume (CBV) 90th percentile extracted from semi-manually delineated contrast enhancing ROIs, SVM-rbf, and RUSBoost achieve BAR–values of 0.947 and 0.932, respectively. Our findings show that AdaBoost, SVM-rbf, and

  18. 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.

  19. Use of susceptibility-weighted imaging in assessing ischemic penumbra

    PubMed Central

    Wu, Xiujuan; Luo, Song; Wang, Ying; Chen, Yang; Liu, Jun; Bai, Jing; Feng, Jiachun; Zhang, Hongliang

    2017-01-01

    Abstract Rationale: The ischemic penumbra assessment is essential for the subsequent therapy and prediction of evolution in patients with acute ischemic infraction. Although controversial as a perfect equivalence to penumbra, perfusion-weighted imaging (PWI)-diffusion-weighted imaging (DWI) mismatch may predict the response to thrombolysis. Due to the reliance of PWI on contrast agents, noninvasive alternatives remain an unmet need. Patient concerns: We reported a 65-year-old man complained of paroxysmal hemiplegia of his right limbs and anepia for 2 days, whereas the symptoms lasted for about 12 hours when he admitted to the hospital. Diagnosis: We diagnosed it as acute ischemic stroke caused by the left middle cerebral artery stenosis. Interventions: Susceptibility-weighted imaging (SWI), multimodal magnetic resonance imaging (MRI) work-up which includes conventional MRI sequences (T1WI, T2WI, and FLAIR), DWI, PWI. Outcomes: His DWI-SWI mismatch was comparable to that of DWI-PWI at admission, suggesting that DWI-SWI could predict ischemic penumbra in patient with acute infarction. He refused the digital subtraction angiography examination or stenting, and he was treated with aspirin, atorvastain, and supportive treatment. The patient received a reexamination of the conventional MRI and SWI 11 days later. Expansion of the infarction in the affected MCA territory resulted from the penumbra indicated by the mismatch between DWI-SWI. Lessons: SWI can be used as a noninvasive alternative to evaluate the ischemic penumbra. Besides, SWI can provide perfusion information comparable to PWI and SWI is sufficient to identify occlusive arteries. PMID:28178170

  20. SU-F-303-13: Initial Evaluation of Four Dimensional Diffusion- Weighted MRI (4D-DWI) and Its Effect On Apparent Diffusion Coefficient (ADC) Measurement

    SciTech Connect

    Liu, Y; Yin, F; Czito, B; Bashir, M; Palta, M; Cai, J; Zhong, X; Dale, B

    2015-06-15

    Purpose: Diffusion-weighted imaging(DWI) has been shown to have superior tumor-to-tissue contrast for cancer detection.This study aims at developing and evaluating a four dimensional DWI(4D-DWI) technique using retrospective sorting method for imaging respiratory motion for radiotherapy planning,and evaluate its effect on Apparent Diffusion Coefficient(ADC) measurement. Materials/Methods: Image acquisition was performed by repeatedly imaging a volume of interest using a multi-slice single-shot 2D-DWI sequence in the axial planes and cine MRI(served as reference) using FIESTA sequence.Each 2D-DWI image were acquired in xyz-diffusion-directions with a high b-value(b=500s/mm2).The respiratory motion was simultaneously recorded using bellows.Retrospective sorting was applied in each direction to reconstruct 4D-DWI.The technique was evaluated using a computer simulated 4D-digital human phantom(XCAT),a motion phantom and a healthy volunteer under an IRB-approved study.Motion trajectories of regions-of-interests(ROI) were extracted from 4D-DWI and compared with reference.The mean motion trajectory amplitude differences(D) between the two was calculated.To quantitatively analyze the motion artifacts,XCAT were controlled to simulate regular motion and the motions of 10 liver cancer patients.4D-DWI,free-breathing DWI(FB- DWI) were reconstructed.Tumor volume difference(VD) of each phase of 4D-DWI and FB-DWI from the input static tumor were calculated.Furthermore, ADC was measured for each phase of 4D-DWI and FB-DWI data,and mean tumor ADC values(M-ADC) were calculated.Mean M-ADC over all 4D-DWI phases was compared with M-ADC calculated from FB-DWI. Results: 4D-DWI of XCAT,the motion phantom and the healthy volunteer demonstrated the respiratory motion clearly.ROI D values were 1.9mm,1.7mm and 2.0mm,respectively.For motion artifacts analysis,XCAT 4D-DWI images show much less motion artifacts compare to FB-DWI.Mean VD for 4D-WDI and FB-DWI were 8.5±1.4% and 108±15

  1. Quantitative myocardial perfusion SPECT.

    PubMed

    Tsui, B M; Frey, E C; LaCroix, K J; Lalush, D S; McCartney, W H; King, M A; Gullberg, G T

    1998-01-01

    In recent years, there has been much interest in the clinical application of attenuation compensation to myocardial perfusion single photon emission computed tomography (SPECT) with the promise that accurate quantitative images can be obtained to improve clinical diagnoses. The different attenuation compensation methods that are available create confusion and some misconceptions. Also, attenuation-compensated images reveal other image-degrading effects including collimator-detector blurring and scatter that are not apparent in uncompensated images. This article presents basic concepts of the major factors that degrade the quality and quantitative accuracy of myocardial perfusion SPECT images, and includes a discussion of the various image reconstruction and compensation methods and misconceptions and pitfalls in implementation. The differences between the various compensation methods and their performance are demonstrated. Particular emphasis is directed to an approach that promises to provide quantitative myocardial perfusion SPECT images by accurately compensating for the 3-dimensional (3-D) attenuation, collimator-detector response, and scatter effects. With advances in the computer hardware and optimized implementation techniques, quantitatively accurate and high-quality myocardial perfusion SPECT images can be obtained in clinically acceptable processing time. Examples from simulation, phantom, and patient studies are used to demonstrate the various aspects of the investigation. We conclude that quantitative myocardial perfusion SPECT, which holds great promise to improve clinical diagnosis, is an achievable goal in the near future.

  2. Medial tibial pain: a dynamic contrast-enhanced MRI study.

    PubMed

    Mattila, K T; Komu, M E; Dahlström, S; Koskinen, S K; Heikkilä, J

    1999-09-01

    The purpose of this study was to compare the sensitivity of different magnetic resonance imaging (MRI) sequences to depict periosteal edema in patients with medial tibial pain. Additionally, we evaluated the ability of dynamic contrast-enhanced imaging (DCES) to depict possible temporal alterations in muscular perfusion within compartments of the leg. Fifteen patients with medial tibial pain were examined with MRI. T1-, T2-weighted, proton density axial images and dynamic and static phase post-contrast images were compared in ability to depict periosteal edema. STIR was used in seven cases to depict bone marrow edema. Images were analyzed to detect signs of compartment edema. Region-of-interest measurements in compartments were performed during DCES and compared with controls. In detecting periosteal edema, post-contrast T1-weighted images were better than spin echo T2-weighted and proton density images or STIR images, but STIR depicted the bone marrow edema best. DCES best demonstrated the gradually enhancing periostitis. Four subjects with severe periosteal edema had visually detectable pathologic enhancement during DCES in the deep posterior compartment of the leg. Percentage enhancement in the deep posterior compartment of the leg was greater in patients than in controls. The fast enhancement phase in the deep posterior compartment began slightly slower in patients than in controls, but it continued longer. We believe that periosteal edema in bone stress reaction can cause impairment of venous flow in the deep posterior compartment. MRI can depict both these conditions. In patients with medial tibial pain, MR imaging protocol should include axial STIR images (to depict bone pathology) with T1-weighted axial pre and post-contrast images, and dynamic contrast enhanced imaging to show periosteal edema and abnormal contrast enhancement within a compartment.

  3. Measuring blood delivery to solitary pulmonary nodules using perfusion magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Zheng, Wei; Wang, Zhifeng; Shen, Li; Gao, Ling; Ford, James C.; Makedon, Fillia S.; Pearlman, Justin D.

    2006-03-01

    With perfusion magnetic resonance imaging (pMRI), perfusion describes the amount of blood passing through a block of tissue in a certain period of time. In pMRI, the tissue having more blood passing through will show higher intensity value as more contrast-labeled blood arrives. Perfusion reflects the delivery of essential nutrients to a block of tissue, and is an important parameter for the tissue status. Considering solitary pulmonary nodules (SPN), perfusion differences between malignant and benign nodules have been studied by different techniques. Much effort has been put into its characterization. In this paper, we proposed and implemented extraction of the SPN time intensity profile to measure blood delivery to solitary pulmonary nodules, describing their perfusion effects. In this method, a SPN time intensity profile is created based on intensity values of the solitary pulmonary nodule in lung pMRI images over time. This method has two steps: nodule tracking and profile clustering. Nodule tracking aligns the solitary pulmonary nodule in pMRI images taken at different time points, dealing with nodule movement resulted from breathing and body movement. Profile clustering implements segmentation of the nodule region and extraction of the time intensity profile of a solitary pulmonary nodule. SPN time intensity profiles reflect patterns of blood delivery to solitary pulmonary nodules, giving us a description of perfusion effect and indirect evidence of tumor angiogenesis. Analysis on SPN time intensity profiles will help the diagnosis of malignant nodules for early lung cancer detection.

  4. Mapping of cerebral perfusion territories using territorial arterial spin labeling: techniques and clinical application.

    PubMed

    Hartkamp, Nolan S; Petersen, Esben T; De Vis, Jill B; Bokkers, Reinoud P H; Hendrikse, Jeroen

    2013-08-01

    A knowledge of the exact cerebral perfusion territory which is supplied by any artery is of great importance in the understanding and diagnosis of cerebrovascular disease. The development and optimization of territorial arterial spin labeling (T-ASL) MRI techniques in the past two decades have made it possible to visualize and determine the cerebral perfusion territories in individual patients and, more importantly, to do so without contrast agents or otherwise invasive procedures. This review provides an overview of the development of ASL techniques that aim to visualize the general cerebral perfusion territories or the territory of a specific artery of interest. The first efforts of T-ASL with pulsed, continuous and pseudo-continuous techniques are summarized and subsequent clinical studies using T-ASL are highlighted. In the healthy population, the perfusion territories of the brain-feeding arteries are highly variable. This high variability requires special consideration in specific patient groups, such as patients with cerebrovascular disease, stroke, steno-occlusive disease of the large arteries and arteriovenous malformations. In the past, catheter angiography with selective contrast injection was the only available method to visualize the cerebral perfusion territories in vivo. Several T-ASL methods, sometimes referred to as regional perfusion imaging, are now available that can easily be combined with conventional brain MRI examinations to show the relationship between the cerebral perfusion territories, vascular anatomy and brain infarcts or other pathology. Increased availability of T-ASL techniques on clinical MRI scanners will allow radiologists and other clinicians to gain further knowledge of the relationship between vasculature and patient diagnosis and prognosis. Treatment decisions, such as surgical revascularization, may, in the near future, be guided by information provided by T-ASL MRI in close correlation with structural MRI and quantitative

  5. Ex vivo lung perfusion.

    PubMed

    Reeb, Jeremie; Cypel, Marcelo

    2016-03-01

    Lung transplantation is an established life-saving therapy for patients with end-stage lung disease. Unfortunately, greater success in lung transplantation is hindered by a shortage of lung donors and the relatively poor early-, mid-, and long-term outcomes associated with severe primary graft dysfunction. Ex vivo lung perfusion has emerged as a modern preservation technique that allows for a more accurate lung assessment and improvement in lung quality. This review outlines the: (i) rationale behind the method; (ii) techniques and protocols; (iii) Toronto ex vivo lung perfusion method; (iv) devices available; and (v) clinical experience worldwide. We also highlight the potential of ex vivo lung perfusion in leading a new era of lung preservation.

  6. Pediatric cerebral stroke: susceptibility-weighted imaging may predict post-ischemic malignant edema.

    PubMed

    Bosemani, Thangamadhan; Poretti, Andrea; Orman, Gunes; Meoded, Avner; Huisman, Thierry A G M

    2013-10-01

    Susceptibility-weighted imaging (SWI) is an advanced MRI technique providing information on the blood oxygenation level. Deoxyhemoglobin is increased in hypoperfused tissue characterized by SWI-hypointensity, while high oxyhemoglobin concentration within hyperperfused tissue results in a SWI iso- or hyperintensity compared to healthy brain tissue. We describe a child with a stroke, where SWI in addition to excluding hemorrhage and delineating the thrombus proved invaluable in determining regions of hyperperfusion or luxury perfusion, which contributed further to the prognosis including an increased risk of developing post-ischemic malignant edema.

  7. Pediatric Cerebral Stroke: Susceptibility-Weighted Imaging May Predict Post-Ischemic Malignant Edema

    PubMed Central

    Bosemani, Thangamadhan; Poretti, Andrea; Orman, Gunes; Meoded, Avner; Huisman, Thierry A.G.M.

    2013-01-01

    Summary Susceptibility-weighted imaging (SWI) is an advanced MRI technique providing information on the blood oxygenation level. Deoxyhemoglobin is increased in hypoperfused tissue characterized by SWI-hypointensity, while high oxyhemoglobin concentration within hyperperfused tissue results in a SWI iso- or hyperintensity compared to healthy brain tissue. We describe a child with a stroke, where SWI in addition to excluding hemorrhage and delineating the thrombus proved invaluable in determining regions of hyperperfusion or luxury perfusion, which contributed further to the prognosis including an increased risk of developing post-ischemic malignant edema. PMID:24199819

  8. Quantitative measurement of tissue perfusion and diffusion in vivo.

    PubMed

    Chenevert, T L; Pipe, J G; Williams, D M; Brunberg, J A

    1991-01-01

    Magnetic resonance imaging techniques designed for sensitivity to microscopic motions of water diffusion and blood flow in the capillary network are also exceptionally sensitive to bulk motion properties of the tissue, which may lead to contrast artifact and large quantitative errors. The magnitude of bulk motion error that exists in human brain perfusion/diffusion imaging and the inability of cardiac gating to adequately control this motion are demonstrated by direct measurement of phase stability of voxels localized in the brain. Two methods are introduced to reduce bulk motion phase error. The first, a postprocessing phase correction algorithm, reduces coarse phase error but is inadequate by itself for quantitative perfusion/diffusion MRI. The second method employs orthogonal slice selection gradients to define a column of tissue in the object, from which echoes may be combined in a phase-insensitive manner to measure more reliably the targeted signal attenuation. Applying this acquisition technique and a simplistic model of perfusion and diffusion signal attenuations yields an estimated perfusion fraction of 3.4 +/- 1.1% and diffusion coefficient of 1.1 +/- 0.2 x 10(-5) cm2/s in the white matter of one normal volunteer. Successful separation of perfusion and diffusion effects by this technique is supported in a dynamic study of calf muscle. Periods of normal blood flow, low flow, and reactive hyperemia are clearly distinguished in the quantitative perfusion results, whereas measured diffusion remained nearly constant.

  9. [Portable peristaltic perfusion pumps].

    PubMed

    Magallón Pedrera, I; Soto Torres, I

    1999-11-01

    Portable peristaltic perfusion pumps allow one to administer pharmaceuticals in hospitals as well as in primary health care centers and furthermore these pumps present multiple advantages for patients and their families since they make it possible to carry out treatment in a patient's home while at the same time lowering the costs involved. The authors analyze the most out standing aspects of portable peristaltic perfusion pumps along with their characteristics, installation, programming, and how to turn them on; in addition, the authors list the maintenance care which these pumps require.

  10. Visualization, Quantification and Characterization of Caerulein-Induced Acute Pancreatitis in Rats by 3.0T Clinical MRI, Biochemistry and Histomorphology.

    PubMed

    Yin, Ting; Peeters, Ronald; Liu, Yewei; Feng, Yuanbo; Zhang, Xinyuan; Jiang, Yansheng; Yu, Jie; Dymarkowski, Steven; Himmelreich, Uwe; Oyen, Raymond; Ni, Yicheng

    2017-01-01

    Purpose: To investigate whether Caerulein-induced acute pancreatitis (AP) in rats could be noninvasively studied by clinical magnetic resonance imaging (MRI) techniques and validated by enzymatic biochemistry and histomorphology. Materials and Methods: The study was approved by the institutional animal ethical committee. The AP was induced in 26 rats by intraperitoneal injections of Caerulein, as compared to 6 normal rats. T2-weighted 3D MRI, T2 relaxation measurement and contrast enhanced T1-weighted MRI were performed at 3 Tesla. Pancreatic volume and contrast ratio of pancreas against surrounding tissues were measured by MRI. Animals were scarified at 3, 8, 24 and 48-hr respectively for analyses of serum lipase and amylase levels, and biliopancreatic perfusion-assisted histomorphology. Results: The AP could be observed on MRI 3-hr onwards after Caerulein-administration. T2 relaxation within the pancreas was prolonged due to high water content or edema. Increase of vascular permeability was indicated by T1 contrast enhancement. Both edema and vascular permeability gradually recovered afterwards (p<0.05/0.01), paralleled by declining serum enzyme levels (p<0.05). Microscopy revealed cell vacuolization and edema for early stage, and increased inflammatory cell infiltration and acinar cell loss after 24 and 48-hr. Conclusion: Multiparametric MRI techniques at 3.0T could facilitate noninvasive diagnosis and characterization of Caerulein induced AP in rats, as validated by a novel ex vivo method.

  11. Visualization, Quantification and Characterization of Caerulein-Induced Acute Pancreatitis in Rats by 3.0T Clinical MRI, Biochemistry and Histomorphology

    PubMed Central

    Yin, Ting; Peeters, Ronald; Liu, Yewei; Feng, Yuanbo; Zhang, Xinyuan; Jiang, Yansheng; Yu, Jie; Dymarkowski, Steven; Himmelreich, Uwe; Oyen, Raymond; Ni, Yicheng

    2017-01-01

    Purpose: To investigate whether Caerulein-induced acute pancreatitis (AP) in rats could be noninvasively studied by clinical magnetic resonance imaging (MRI) techniques and validated by enzymatic biochemistry and histomorphology. Materials and Methods: The study was approved by the institutional animal ethical committee. The AP was induced in 26 rats by intraperitoneal injections of Caerulein, as compared to 6 normal rats. T2-weighted 3D MRI, T2 relaxation measurement and contrast enhanced T1-weighted MRI were performed at 3 Tesla. Pancreatic volume and contrast ratio of pancreas against surrounding tissues were measured by MRI. Animals were scarified at 3, 8, 24 and 48-hr respectively for analyses of serum lipase and amylase levels, and biliopancreatic perfusion-assisted histomorphology. Results: The AP could be observed on MRI 3-hr onwards after Caerulein-administration. T2 relaxation within the pancreas was prolonged due to high water content or edema. Increase of vascular permeability was indicated by T1 contrast enhancement. Both edema and vascular permeability gradually recovered afterwards (p<0.05/0.01), paralleled by declining serum enzyme levels (p<0.05). Microscopy revealed cell vacuolization and edema for early stage, and increased inflammatory cell infiltration and acinar cell loss after 24 and 48-hr. Conclusion: Multiparametric MRI techniques at 3.0T could facilitate noninvasive diagnosis and characterization of Caerulein induced AP in rats, as validated by a novel ex vivo method. PMID:28042334

  12. The pediatric template of brain perfusion

    PubMed Central

    Avants, Brian B; Duda, Jeffrey T; Kilroy, Emily; Krasileva, Kate; Jann, Kay; Kandel, Benjamin T; Tustison, Nicholas J; Yan, Lirong; Jog, Mayank; Smith, Robert; Wang, Yi; Dapretto, Mirella; Wang, Danny J J

    2015-01-01

    Magnetic resonance imaging (MRI) captures the dynamics of brain development with multiple modalities that quantify both structure and function. These measurements may yield valuable insights into the neural patterns that mark healthy maturation or that identify early risk for psychiatric disorder. The Pediatric Template of Brain Perfusion (PTBP) is a free and public neuroimaging resource that will help accelerate the understanding of childhood brain development as seen through the lens of multiple modality neuroimaging and in relation to cognitive and environmental factors. The PTBP uses cross-sectional and longitudinal MRI to quantify cortex, white matter, resting state functional connectivity and brain perfusion, as measured by Arterial Spin Labeling (ASL), in 120 children 7–18 years of age. We describe the PTBP and show, as a demonstration of validity, that global summary measurements capture the trajectories that demarcate critical turning points in brain maturation. This novel resource will allow a more detailed understanding of the network-level, structural and functional landmarks that are obtained during normal adolescent brain development. PMID:25977810

  13. The pediatric template of brain perfusion.

    PubMed

    Avants, Brian B; Duda, Jeffrey T; Kilroy, Emily; Krasileva, Kate; Jann, Kay; Kandel, Benjamin T; Tustison, Nicholas J; Yan, Lirong; Jog, Mayank; Smith, Robert; Wang, Yi; Dapretto, Mirella; Wang, Danny J J

    2015-01-01

    Magnetic resonance imaging (MRI) captures the dynamics of brain development with multiple modalities that quantify both structure and function. These measurements may yield valuable insights into the neural patterns that mark healthy maturation or that identify early risk for psychiatric disorder. The Pediatric Template of Brain Perfusion (PTBP) is a free and public neuroimaging resource that will help accelerate the understanding of childhood brain development as seen through the lens of multiple modality neuroimaging and in relation to cognitive and environmental factors. The PTBP uses cross-sectional and longitudinal MRI to quantify cortex, white matter, resting state functional connectivity and brain perfusion, as measured by Arterial Spin Labeling (ASL), in 120 children 7-18 years of age. We describe the PTBP and show, as a demonstration of validity, that global summary measurements capture the trajectories that demarcate critical turning points in brain maturation. This novel resource will allow a more detailed understanding of the network-level, structural and functional landmarks that are obtained during normal adolescent brain development.

  14. A study on the flip angle for an optimal T1-weighted image based on the 3D-THRIVE MRI technique: Focusing on the detection of a hepatocellular carcinoma (HCC)

    NASA Astrophysics Data System (ADS)

    Dong, Kyung-Rae; Goo, Eun-Hoe; Lee, Jae-Seung; Chung, Woon-Kwan; Kim, Young-Jae

    2014-04-01

    This study examined the optimal flip angle (FA) for a T1-weighted image in the detection of a hepatocellular carcinoma (HCC). A 3D-T1-weighted high-resolution isotropic volume examination (THRIVE) technique was used to determine the dependence of the signal to noise ratio (SNR) and the contrast-to-noise ratio (CNR) on the change in FA. This study targeted 40 liver cancer patients (25 men and 15 women aged 50 to 70 years with a mean age of 60.32 ± 6.2 years) who visited this hospital to undergo an abdominal MRI examination from January to June 2013. A 3.0 Tesla MRI machine (Philips, Medical System, Achieva) and a MRI receiver coil for data reception with a 16-channel multicoil were used in this study. The THRIVE (repetition time (TR): 8.1 ms, echo time (TE): 3.7 ms, matrix: 172 × 172, slice thickness: 4 mm, gap: 2 mm, field of view (FOV): 350 mm, and band width (BW): 380.1 Hz) technique was applied as a pulse sequence. The time required for the examination was 19 seconds, and the breath-hold technique was used. Axial images were obtained at five FAs: 5, 10, 15, 20 and 25°. The signal intensities of the liver, the lesion and the background noise were measured based on the acquired images before the SNR and the CNR were calculated. To evaluate the image at the FA, we used SPSS for Windows ver. 17.0 to conduct a one-way ANOVA test. A Bonferroni test was conducted as a post-hoc test. The SNRs of the hemorrhagic HCC in the 3D-THRIVE technique were 35.50 ± 4.12, 97.00 ± 10.24, 66.09 ± 7.29, 53.84 ± 5.43, and 42.92 ± 5.11 for FAs of 5, 10, 15, 20, and 25°, respectively (p = 0.0430), whereas the corresponding CNRs were 30.50 ± 3.84, 43.00 ± 5.42, 36.54 ± 4.09, 32.30 ± 2.79, and 31.69 ± 3.21 (p = 0.0003). At a small FA of 10, the SNR and the CNR showed the highest values. As the FA was increased, the SNR and the CNR values showed a decreasing tendency. In conclusion, the optimal T1-weighted image FA should be set to 10° to detect a HCC by using the 3D

  15. The measurement of diffusion and perfusion in biological systems using magnetic resonance imaging.

    PubMed

    Thomas, D L; Lythgoe, M F; Pell, G S; Calamante, F; Ordidge, R J

    2000-08-01

    The aim of this review is to describe two recent developments in the use of magnetic resonance imaging (MRI) in the study of biological systems: diffusion and perfusion MRI. Diffusion MRI measures the molecular mobility of water in tissue, while perfusion MRI measures the rate at which blood is delivered to tissue. Therefore, both these techniques measure quantities which have direct physiological relevance. It is shown that diffusion in biological systems is a complex phenomenon, influenced directly by tissue microstructure, and that its measurement can provide a large amount of information about the organization of this structure in normal and diseased tissue. Perfusion reflects the delivery of essential nutrients to tissue, and so is directly related to its status. The concepts behind the techniques are explained, and the theoretical models that are used to convert MRI data to quantitative physical parameters are outlined. Examples of current applications of diffusion and perfusion MRI are given. In particular, the use of the techniques to study the pathophysiology of cerebral ischaemia/stroke is described. It is hoped that the biophysical insights provided by this approach will help to define the mechanisms of cell damage and allow evaluation of therapies aimed at reducing this damage.

  16. Clinical Use of CT Perfusion For Diagnosis and Prediction of Lesion Growth in Acute Ischemic Stroke

    PubMed Central

    Huisa, Branko N; Neil, William P; Schrader, Ronald; Maya, Marcel; Pereira, Benedict; Bruce, Nhu T; Lyden, Patrick D

    2012-01-01

    Background and Purpose CT perfusion (CTP) mapping in research centers correlates well with diffusion weighted imaging (DWI) lesions and may accurately differentiate the infarct core from ischemic penumbra. The value of CTP in real-world clinical practice has not been fully established. We investigated the yield of CTP– derived cerebral blood volume (CBV) and mean transient time (MTT) for the detection of cerebral ischemia and ischemic penumbra in a sample of acute ischemic stroke (AIS) patients. Methods We studied 165 patients with initial clinical symptoms suggestive of AIS. All patients had an initial non-contrast head CT, CT Perfusion (CTP), CT angiogram (CTA) and follow up brain MRI. The obtained perfusion images were used for image processing. CBV, MTT and DWI lesion volumes were visually estimated and manually traced. Statistical analysis was done using R-2.14.and SAS 9.1. Results All normal DWI sequences had normal CBV and MTT studies (N=89). Seventy-three patients had acute DWI lesions. CBV was abnormal in 23.3% and MTT was abnormal in 42.5% of these patients. There was a high specificity (91.8%)but poor sensitivity (40.0%) for MTT maps predicting positive DWI. Spearman correlation was significant between MTT and DWI lesions (ρ=0.66, p>0.0001) only for abnormal MTT and DWI lesions>0cc. CBV lesions did not correlate with final DWI. Conclusions In real-world use, acute imaging with CTP did not predict stroke or DWI lesions with sufficient accuracy. Our findings argue against the use of CTP for screening AIS patients until real-world implementations match the accuracy reported from specialized research centers. PMID:23253533

  17. Three-dimensional whole-brain perfusion quantification using pseudo-continuous arterial spin labeling MRI at multiple post-labeling delays: accounting for both arterial transit time and impulse response function.

    PubMed

    Qin, Qin; Huang, Alan J; Hua, Jun; Desmond, John E; Stevens, Robert D; van Zijl, Peter C M

    2014-02-01

    Measurement of the cerebral blood flow (CBF) with whole-brain coverage is challenging in terms of both acquisition and quantitative analysis. In order to fit arterial spin labeling-based perfusion kinetic curves, an empirical three-parameter model which characterizes the effective impulse response function (IRF) is introduced, which allows the determination of CBF, the arterial transit time (ATT) and T(1,eff). The accuracy and precision of the proposed model were compared with those of more complicated models with four or five parameters through Monte Carlo simulations. Pseudo-continuous arterial spin labeling images were acquired on a clinical 3-T scanner in 10 normal volunteers using a three-dimensional multi-shot gradient and spin echo scheme at multiple post-labeling delays to sample the kinetic curves. Voxel-wise fitting was performed using the three-parameter model and other models that contain two, four or five unknown parameters. For the two-parameter model, T(1,eff) values close to tissue and blood were assumed separately. Standard statistical analysis was conducted to compare these fitting models in various brain regions. The fitted results indicated that: (i) the estimated CBF values using the two-parameter model show appreciable dependence on the assumed T(1,eff) values; (ii) the proposed three-parameter model achieves the optimal balance between the goodness of fit and model complexity when compared among the models with explicit IRF fitting; (iii) both the two-parameter model using fixed blood T1 values for T(1,eff) and the three-parameter model provide reasonable fitting results. Using the proposed three-parameter model, the estimated CBF (46 ± 14 mL/100 g/min) and ATT (1.4 ± 0.3 s) values averaged from different brain regions are close to the literature reports; the estimated T(1,eff) values (1.9 ± 0.4 s) are higher than the tissue T1 values, possibly reflecting a contribution from the microvascular arterial blood compartment.

  18. Investigation of cyano-bridged coordination nanoparticles Gd3+/[Fe(CN)6]3-/d-mannitol as T1-weighted MRI contrast agents

    NASA Astrophysics Data System (ADS)

    Perrier, M.; Gallud, A.; Ayadi, A.; Kennouche, S.; Porredon, C.; Gary-Bobo, M.; Larionova, J.; Goze-Bac, Ch.; Zanca, M.; Garcia, M.; Basile, I.; Long, J.; de Lapuente, J.; Borras, M.; Guari, Y.

    2015-07-01

    Cyano-bridged Gd3+/[Fe(CN)6]3- coordination polymer nanoparticles of 3-4 nm stabilized with d-mannitol presenting a high r1 relaxivity value of 11.4 mM-1 s-1 were investigated in vivo as contrast agents (CA) for Magnetic Resonance Imaging (MRI). They allow an increase of the MR image contrast and can act as an efficient intravascular T1 CA with a relatively long blood-circulation lifetime (60 min) without specific toxicity.Cyano-bridged Gd3+/[Fe(CN)6]3- coordination polymer nanoparticles of 3-4 nm stabilized with d-mannitol presenting a high r1 relaxivity value of 11.4 mM-1 s-1 were investigated in vivo as contrast agents (CA) for Magnetic Resonance Imaging (MRI). They allow an increase of the MR image contrast and can act as an efficient intravascular T1 CA with a relatively long blood-circulation lifetime (60 min) without specific toxicity. Electronic supplementary information (ESI) available: Experimental details and procedures, toxicological data, physical characterization. See DOI: 10.1039/c5nr01557j

  19. Measurement of the weighted peak level for occupational exposure to gradient magnetic fields for 1.5 and 3 Tesla MRI body scanners.

    PubMed

    Bonutti, F; Tecchio, M; Maieron, M; Trevisan, D; Negro, C; Calligaris, F

    2016-03-01

    The purpose of this work is to give a contribution to the construction of a comprehensive knowledge of the exposure levels to gradient magnetic fields (GMF) in terms of the weighed peak (WP), especially for 3 Tesla scanners for which there are still few works available in the literature. A new generation probe for the measurement of electromagnetic fields in the range of 1 Hz-400 kHz was used to assess the occupational exposure levels to the GMF for 1.5 and 3.0 Tesla MRI body scanners, using the method of the WP according to the International Commission on Non-Ionizing Radiation Protection (ICNIRP) approach. The probe was placed at a height of 1.1 m, close to the MRI scanners, where operators could stay during some medical procedures with particular issues. The measurements were performed for a set of typical acquisition sequences for body (liver) and head exams. The measured values of WP were in compliance with ICNIRP 2010 reference levels for occupational exposures.

  20. Arterial Perfusion Imaging-Defined Subvolume of Intrahepatic Cancer

    PubMed Central

    Wang, Hesheng; Farjam, Reza; Feng, Mary; Hussain, Hero; Ten Haken, Randall K.; Lawrence, Theodore S.; Cao, Yue

    2014-01-01

    Purpose To assess whether an increase in a subvolume of intrahepatic tumor with elevated arterial perfusion during radiation therapy (RT) predicts tumor progression post RT. Methods and Materials Twenty patients with unresectable intrahepatic cancers undergoing RT were enrolled in a prospective IRB-approved study. Dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) were performed prior to RT (pre-RT), after delivering ~60% of the planned dose (mid-RT) and one month after completion of RT to quantify hepatic arterial perfusion. The arterial perfusions of the tumors at pre-RT were clustered into low-normal and elevated perfusion by a fuzzy clustering-based method, and the tumor subvolumes with elevated arterial perfusion were extracted from the hepatic arterial perfusion images. The percentage changes in the tumor subvolumes and means of arterial perfusion over the tumors from pre-RT to mid-RT were evaluated for predicting tumor progression post-RT. Results Of the 24 tumors, 6 tumors in 5 patients progressed 5–21 months after RT completion. Neither tumor volumes nor means of tumor arterial perfusion at pre-RT were predictive of treatment outcome. The mean arterial perfusion over the tumors increased significantly at mid-RT in progressive tumors comparing to the responsive ones (p=0.006). From pre-RT to mid-RT, the responsive tumors had a decrease in the tumor subvolumes with elevated arterial perfusion (median: −14%, range: −75% – 65%), while the progressing tumors had an increase of the subvolumes (median: 57%, range: −7% – 165%) (p=0.003). Receiver operating characteristic (ROC) analysis of the percentage change in the subvolume for predicting tumor progression post-RT had an area under the curve (AUC) of 0.90. Conclusion The increase in the subvolume of the intrahepatic tumor with elevated arterial perfusion during RT has the potential to be a predictor for tumor progression post-RT. The tumor subvolume could be a radiation boost candidate

  1. Kinetic assessment of manganese using magnetic resonance imaging in the dually perfused human placenta in vitro

    SciTech Connect

    Miller, R.K.; Mattison, D.R.; Panigel, M.; Ceckler, T.; Bryant, R.; Thomford, P.

    1987-10-01

    The transfer and distribution of paramagnetic manganese was investigated in the dually perfused human placenta in vitro (using 10, 20, 100 ..mu..M Mn with and without /sup 54/Mn) using magnetic resonance imaging (MRI) and conventional radiochemical techniques. The human placenta concentrated /sup 54/Mn rapidly during the first 15 min of perfusion and by 4 hr was four times greater than the concentrations of Mn in the maternal perfusate, while the concentration of Mn in the fetal perfusate was 25% of the maternal perfusate levels. Within placentae, 45% of the /sup 54/Mn was free in the 100,000g supernatant, with 45% in the 1000g pellet. The magnetic field dependence of proton nuclear spin-lattice relaxation time (T/sub 1/) in placental tissue supports this Mn binding. Mn primarily affected the MRI partial saturation rather than spin-echo images of the human placenta, which provided for the separation of perfusate contributions from those produced by Mn. The washout of the Mn from the placenta was slow compared with its uptake, as determined by MRI. Thus, Mn was concentrated by the human placenta, but transfer of Mn across the placenta was limited in either direction. These studies also illustrate the opportunity for studies of human placental function using magnetic resonance imaging as a noninvasive biomarker.

  2. Ventilation and perfusion magnetic resonance imaging of the lung

    PubMed Central

    Bauman, Grzegorz; Eichinger, Monika

    2012-01-01

    Summary A close interaction between the respiratory pump, pulmonary parenchyma and blood circulation is essential for a normal lung function. Many pulmonary diseases present, especially in their initial phase, a variable regional impairment of ventilation and perfusion. In the last decades various techniques have been established to measure the lung function. Besides the global pulmonary function tests (PFTs) imaging techniques gained increasing importance to detect local variations in lung function, especially for ventilation and perfusion assessment. Imaging modalities allow for a deeper regional insight into pathophysiological processes and enable improved planning of invasive procedures. In contrast to computed tomography (CT) and the nuclear medicine techniques, magnetic resonance imaging (MRI), as a radiation free imaging modality gained increasing importance since the early 1990 for the assessment of pulmonary function. The major inherent problems of lung tissue, namely the low proton density and the pulmonary and cardiac motion, were overcome in the last years by a constant progress in MR technology. Some MR techniques are still under development, a process which is driven by scientific questions regarding the physiology and pathophysiology of pulmonary diseases, as well as by the need for fast and robust clinically applicable imaging techniques as safe therapy monitoring tools. MRI can be considered a promising ionizing-free alternative to techniques like CT or nuclear medicine techniques for the evaluation of lung function. The goal of this article is to provide an overview on selected MRI techniques for the assessment of pulmonary ventilation and perfusion. PMID:22802864

  3. Qualitative Perfusion Cardiac Magnetic Resonance Imaging Lacks Sensitivity in Detecting Cardiac Allograft Vasculopathy

    PubMed Central

    Colvin-Adams, Monica; Petros, Salam; Raveendran, Ganesh; Missov, Emil; Medina, Eduardo; Wilson, Robert

    2011-01-01

    Background Cardiac allograft vasculopathy (CAV) is a major complication after heart transplantation, requiring frequent surveillance angiography. Though cardiac angiography is the gold standard, it is insensitive in detecting transplant vasculopathy and invasive. Perfusion MRI provides a noninvasive alternative and possibly a useful modality for studying CAV. We sought to compare the accuracy of qualitative perfusion MRI to coronary angiography in detecting CAV. Methods A retrospective analysis was performed in 68 heart transplant recipients who had simultaneous surveillance cardiac MRI and coronary angiogram and who underwent transplantation between 2000 and 2007. We compared results of qualitative MRI to those of the cardiac angiogram. Sensitivity and specificity of MR were calculated. Results Sixty-eight patients underwent both cardiac MRI and coronary angiogram. 73.5% were male; mean age was 45.37 ± 14 years. Mean duration of heart transplantation was 7.9 ± 5.2 years. The mean ejection fraction was 55% in the patients without CAV and 57.4% in those with CAV. There were 48 normal and 24 abnormal MRI studies. The overall sensitivity was 41% and specificity was 74%. Conclusions Qualitative assessment of perfusion cardiac MR has low sensitivity and moderate specificity for detecting CAV. The sensitivity of MRI was slightly improved with severity of disease.

  4. Influence of 100% and 40% oxygen on penumbral blood flow, oxygen level, and T2*-weighted MRI in a rat stroke model.

    PubMed

    Baskerville, Tracey A; Deuchar, Graeme A; McCabe, Christopher; Robertson, Craig A; Holmes, William M; Santosh, Celestine; Macrae, I Mhairi

    2011-08-01

    Accurate imaging of the ischemic penumbra is a prerequisite for acute clinical stroke research. T(2)(*) magnetic resonance imaging (MRI) combined with an oxygen challenge (OC) is being developed to detect penumbra based on changes in blood deoxyhemoglobin. However, inducing OC with 100% O(2) induces sinus artefacts on human scans and influences cerebral blood flow (CBF), which can affect T(2)(*) signal. Therefore, we investigated replacing 100% O(2) OC with 40% O(2) OC (5 minutes 40% O(2) versus 100% O(2)) and determined the effects on blood pressure (BP), CBF, tissue pO(2), and T(2)(*) signal change in presumed penumbra in a rat stroke model. Probes implanted into penumbra and contralateral cortex simultaneously recorded pO(2) and CBF during 40% O(2) (n=6) or 100% O(2) (n=8) OC. In a separate MRI study, T(2)(*) signal change to 40% O(2) (n=6) and 100% O(2) (n=5) OC was compared. Oxygen challenge (40% and 100% O(2)) increased BP by 8.2% and 18.1%, penumbra CBF by 5% and 15%, and penumbra pO(2) levels by 80% and 144%, respectively. T(2)(*) signal significantly increased by 4.56% ± 1.61% and 8.65% ± 3.66% in penumbra compared with 2.98% ± 1.56% and 2.79% ± 0.66% in contralateral cortex and 1.09% ± 0.82% and -0.32% ± 0.67% in ischemic core, respectively. For diagnostic imaging, 40% O(2) OC could provide sufficient T(2)(*) signal change to detect penumbra with limited influence in BP and CBF.

  5. Influence of 100% and 40% oxygen on penumbral blood flow, oxygen level, and T2*-weighted MRI in a rat stroke model

    PubMed Central

    Baskerville, Tracey A; Deuchar, Graeme A; McCabe, Christopher; Robertson, Craig A; Holmes, William M; Santosh, Celestine; Macrae, I Mhairi

    2011-01-01

    Accurate imaging of the ischemic penumbra is a prerequisite for acute clinical stroke research. T2* magnetic resonance imaging (MRI) combined with an oxygen challenge (OC) is being developed to detect penumbra based on changes in blood deoxyhemoglobin. However, inducing OC with 100% O2 induces sinus artefacts on human scans and influences cerebral blood flow (CBF), which can affect T2* signal. Therefore, we investigated replacing 100% O2 OC with 40% O2 OC (5 minutes 40% O2 versus 100% O2) and determined the effects on blood pressure (BP), CBF, tissue p2, and T2* signal change in presumed penumbra in a rat stroke model. Probes implanted into penumbra and contralateral cortex simultaneously recorded p2 and CBF during 40% O2 (n=6) or 100% O2 (n=8) OC. In a separate MRI study, T2* signal change to 40% O2 (n=6) and 100% O2 (n=5) OC was compared. Oxygen challenge (40% and 100% O2) increased BP by 8.2% and 18.1%, penumbra CBF by 5% and 15%, and penumbra p2 levels by 80% and 144%, respectively. T2* signal significantly increased by 4.56%±1.61% and 8.65%±3.66% in penumbra compared with 2.98%±1.56% and 2.79%±0.66% in contralateral cortex and 1.09%±0.82% and −0.32%±0.67% in ischemic core, respectively. For diagnostic imaging, 40% O2 OC could provide sufficient T2* signal change to detect penumbra with limited influence in BP and CBF. PMID:21559031

  6. Inverse Z-spectrum analysis for spillover-, MT-, and T1 -corrected steady-state pulsed CEST-MRI--application to pH-weighted MRI of acute stroke.

    PubMed

    Zaiss, Moritz; Xu, Junzhong; Goerke, Steffen; Khan, Imad S; Singer, Robert J; Gore, John C; Gochberg, Daniel F; Bachert, Peter

    2014-03-01

    Endogenous chemical exchange saturation transfer (CEST) effects are always diluted by competing effects, such as direct water proton saturation (spillover) and semi-solid macromolecular magnetization transfer (MT). This leads to unwanted T2 and MT signal contributions that lessen the CEST signal specificity to the underlying biochemical exchange processes. A spillover correction is of special interest for clinical static field strengths and protons resonating near the water peak. This is the case for all endogenous CEST agents, such as amide proton transfer, -OH-CEST of glycosaminoglycans, glucose or myo-inositol, and amine exchange of creatine or glutamate. All CEST effects also appear to be scaled by the T1 relaxation time of water, as they are mediated by the water pool. This forms the motivation for simple metrics that correct the CEST signal. Based on eigenspace theory, we propose a novel magnetization transfer ratio (MTRRex ), employing the inverse Z-spectrum, which eliminates spillover and semi-solid MT effects. This metric can be simply related to Rex , the exchange-dependent relaxation rate in the rotating frame, and ka , the inherent exchange rate. Furthermore, it can be scaled by the duty cycle, allowing for simple translation to clinical protocols. For verification, the amine proton exchange of creatine in solutions with different agar concentrations was studied experimentally at a clinical field strength of 3 T, where spillover effects are large. We demonstrate that spillover can be properly corrected and that quantitative evaluation of pH and creatine concentration is possible. This proves that MTRRex is a quantitative and biophysically specific CEST-MRI metric. Applied to acute stroke induced in rat brain, the corrected CEST signal shows significantly higher contrast between the stroke area and normal tissue, as well as less B1 dependence, than conventional approaches.

  7. Effect of combined VEGF165/ SDF-1 gene therapy on vascular remodeling and blood perfusion in cerebral ischemia.

    PubMed

    Hu, Guo-Jie; Feng, Yu-Gong; Lu, Wen-Peng; Li, Huan-Ting; Xie, Hong-Wei; Li, Shi-Fang

    2016-12-16

    OBJECTIVE Therapeutic neovascularization is a promising strategy for treating patients after an ischemic stroke; however, single-factor therapy has limitations. Stromal cell-derived factor 1 (SDF-1) and vascular endothelial growth factor (VEGF) proteins synergistically promote angiogenesis. In this study, the authors assessed the effect of combined gene therapy with VEGF165 and SDF-1 in a rat model of cerebral infarction. METHODS An adenoviral vector expressing VEGF165 and SDF-1 connected via an internal ribosome entry site was constructed (Ad- VEGF165-SDF-1). A rat model of middle cerebral artery occlusion (MCAO) was established; either Ad- VEGF165-SDF-1 or control adenovirus Ad- LacZ was stereotactically microinjected into the lateral ventricle of 80 rats 24 hours after MCAO. Coexpression and distribution of VEGF165 and SDF-1 were examined by reverse-transcription polymerase chain reaction, Western blotting, and immunofluorescence. The neurological severity score of each rat was measured on Days 3, 7, 14, 21, and 28 after MCAO. Angiogenesis and vascular remodeling were evaluated via bromodeoxyuridine and CD34 immunofluorescence labeling. Relative cerebral infarction volumes were determined by T2-weighted MRI and triphenyltetrazolium chloride staining. Cerebral blood flow, relative cerebral blood volume, and relative mean transmit time were assessed using perfusion-weighted MRI. RESULTS The Ad- VEGF165-SDF-1 vector mediated coexpression of VEGF165 and SDF-1 in multiple sites around the ischemic core, including the cortex, corpus striatum, and hippocampal granular layer. Coexpression of VEGF165 and SDF-1 improved neural function, reduced cerebral infarction volume, increased microvascular density and promoted angiogenesis in the ischemic penumbra, and improved cerebral blood flow and perfusion. CONCLUSIONS Combined VEGF165 and SDF-1 gene therapy represents a potential strategy for improving vascular remodeling and recovery of neural function after cerebral

  8. Thrombolysis, Complete Recanalization, Diffusion Reversal, and Luxury Perfusion in Hyperacute Stroke.

    PubMed

    Sakamoto, Yuki; Ouchi, Takahiro; Okubo, Seiji; Abe, Arata; Aoki, Junya; Nogami, Akane; Sato, Takahiro; Hokama, Hiroyuki; Ogawa, Yutaro; Suzuki, Shizuka; Mishina, Masahiro; Kimura, Kazumi

    2016-01-01

    A 59-year old man was admitted to our stroke care unit 1.8 hours after onset of cardioembolic stroke. Administration of issue-plasminogen activator achieved complete recanalization, and his lesion on diffusion-weighted imaging (DWI) disappeared and single photon emission computed tomography showed luxury perfusion. DWI reversal and luxury perfusion were sometimes observed in hyperacute stroke patients, especially timely reperfusion was achieved. However, the relationships between DWI reversal and luxury perfusion were not well known. Transient DWI reversal may be associated with luxury perfusion in patients treated with t-PA, via early complete recanalization achieved by thrombolysis.

  9. Harmonic analysis of perfusion pumps.

    PubMed

    Dougherty, F Carroll; Donovan, F M; Townsley, Mary I

    2003-12-01

    The controversy over the use of nonpulsatile versus pulsatile pumps for maintenance of normal organ function during ex vivo perfusion has continued for many years, but resolution has been limited by lack of a congruent mathematical definition of pulsatility. We hypothesized that the waveform frequency and amplitude, as well as the underlying mean distending pressure are all key parameters controlling vascular function. Using discrete Fourier Analysis, our data demonstrate the complexity of the pulmonary arterial pressure waveform in vivo and the failure of commonly available perfusion pumps to mimic in vivo dynamics. In addition, our data show that the key harmonic signatures are intrinsic to the perfusion pumps, are similar for flow and pressure waveforms, and are unchanged by characteristics of the downstream perfusion circuit or perfusate viscosity.

  10. Functional lung imaging using hyperpolarized gas MRI.

    PubMed

    Fain, Sean B; Korosec, Frank R; Holmes, James H; O'Halloran, Rafael; Sorkness, Ronald L; Grist, Thomas M

    2007-05-01

    The noninvasive assessment of lung function using imaging is increasingly of interest for the study of lung diseases, including chronic obstructive pulmonary disease (COPD) and asthma. Hyperpolarized gas MRI (HP MRI) has demonstrated the ability to detect changes in ventilation, perfusion, and lung microstructure that appear to be associated with both normal lung development and disease progression. The physical characteristics of HP gases and their application to MRI are presented with an emphasis on current applications. Clinical investigations using HP MRI to study asthma, COPD, cystic fibrosis, pediatric chronic lung disease, and lung transplant are reviewed. Recent advances in polarization, pulse sequence development for imaging with Xe-129, and prototype low magnetic field systems dedicated to lung imaging are highlighted as areas of future development for this rapidly evolving technology.

  11. Relative indexes of cutaneous blood perfusion measured by real-time laser Doppler imaging (LDI) in healthy volunteers.

    PubMed

    Seyed Jafari, S Morteza; Schawkat, Megir; Van De Ville, Dimitri; Shafighi, Maziar

    2014-07-01

    We used real-time LDI to study regional variations in microcirculatory perfusion in healthy candidates to establish a new methodology for global perfusion body mapping that is based on intra-individual perfusion index ratios. Our study included 74 (37 female) healthy volunteers aged between 22 and 30 years (mean 24.49). Imaging was performed using a recent microcirculation-imaging camera (EasyLDI) for different body regions of each volunteer. The perfusion values were reported in Arbitrary Perfusion Units (APU). The relative perfusion indexes for each candidate's body region were then obtained by normalization with the perfusion value of the forehead. Basic parameters such as weight, height, and blood pressure were also measured and analyzed. The highest mean perfusion value was reported in the forehead area (259.21APU). Mean perfusion in the measured parts of the body correlated positively with mean forehead value, while there was no significant correlation between forehead blood perfusion values and room temperature, BMI, systolic blood pressure and diastolic blood pressure (p=0.420, 0.623, 0.488, 0.099, respectively). Analysis of the data showed that perfusion indexes were not significantly different between male and female volunteers except for the ventral upper arm area (p=.001). LDI is a non-invasive, fast technique that opens several avenues for clinical applications. The mean perfusion indexes are useful in clinical practice for monitoring patients before and after surgical interventions. Perfusion values can be predicted for different body parts for patients only by taking the forehead perfusion value and using the perfusion index ratios to obtain expected normative perfusion values.

  12. Shoulder MRI

    MedlinePlus

    ... magnetic field of the MRI unit, metal and electronic items are not allowed in the exam room. ... tell the technologist if you have medical or electronic devices in your body. These objects may interfere ...

  13. Knee MRI

    MedlinePlus

    ... magnetic field of the MRI unit, metal and electronic items are not allowed in the exam room. ... tell the technologist if you have medical or electronic devices in your body. These objects may interfere ...

  14. Shoulder MRI

    MedlinePlus

    ... of the shoulder uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of ... scans, MRI does not utilize ionizing radiation. Instead, radio waves redirect alignment of hydrogen atoms that naturally exist ...

  15. Knee MRI

    MedlinePlus

    ... of the knee uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of ... scans, MRI does not utilize ionizing radiation. Instead, radio waves redirect alignment of hydrogen atoms that naturally exist ...

  16. MRI renaissance.

    PubMed

    Hensley, S

    1997-12-01

    A few years ago, magnetic resonance imaging was healthcare's version of a foreign sports car-flashy, expensive and impractical. Now, after years in the doldrums, sales of MRI systems are roaring back. An aging fleet of MRI scanners due for replacement and a hearty increase in doctors' use of the versatile imaging tools are combining to fuel the surge in demand, vendors and customers say.

  17. Ex vivo lung perfusion

    PubMed Central

    Machuca, Tiago N.

    2014-01-01

    Lung transplantation (LTx) is an established treatment option for eligible patients with end-stage lung disease. Nevertheless, the imbalance between suitable donor lungs available and the increasing number of patients considered for LTx reflects in considerable waitlist mortality. Among potential alternatives to address this issue, ex vivo lung perfusion (EVLP) has emerged as a modern preservation technique that allows for more accurate lung assessment and also improvement of lung function. Its application in high-risk donor lungs has been successful and resulted in safe expansion of the donor pool. This article will: (I) review the technical details of EVLP; (II) the rationale behind the method; (III) report the worldwide clinical experience with the EVLP, including the Toronto technique and others; (IV) finally, discuss the growing literature on EVLP application for donation after cardiac death (DCD) lungs. PMID:25132972

  18. Application of intravoxel incoherent motion perfusion imaging to shoulder muscles after a lift-off test of varying duration.

    PubMed

    Nguyen, Audrey; Ledoux, Jean-Baptiste; Omoumi, Patrick; Becce, Fabio; Forget, Joachim; Federau, Christian

    2016-01-01

    Intravoxel incoherent motion (IVIM) MRI is a method to extract microvascular blood flow information out of diffusion-weighted images acquired at multiple b-values. We hypothesized that IVIM can identify the muscles selectively involved in a specific task, by measuring changes in activity-induced local muscular perfusion after exercise. We tested this hypothesis using a widely used clinical maneuver, the lift-off test, which is known to assess specifically the subscapularis muscle functional integrity. Twelve shoulders from six healthy male volunteers were imaged at 3 T, at rest, as well as after a lift-off test hold against resistance for 30 s, 1 and 2 min respectively, in three independent sessions. IVIM parameters, consisting of perfusion fraction (f), diffusion coefficient (D), pseudo-diffusion coefficient D* and blood flow-related fD*, were estimated within outlined muscles of the rotator cuff and the deltoid bundles. The mean values at rest and after the lift-off tests were compared in each muscle using a one-way ANOVA. A statistically significant increase in fD* was measured in the subscapularis, after a lift-off test of any duration, as well as in D. A fD* increase was the most marked (30 s, +103%; 1 min, +130%; 2 min, +156%) and was gradual with the duration of the test (in 10(-3) mm(2) /s: rest, 1.41 ± 0.50; 30 s, 2.86 ± 1.17; 1 min, 3.23 ± 1.22; 2 min, 3.60 ± 1.21). A significant increase in fD* and D was also visible in the posterior bundle of the deltoid. No significant change was consistently visible in the other investigated muscles of the rotator cuff and the other bundles of the deltoid. In conclusion, IVIM fD* allows the demonstration of a task-related microvascular perfusion increase after a specific task and suggests a direct relationship between microvascular perfusion and the duration of the effort. It is a promising method to investigate non-invasively skeletal muscle physiology and clinical perfusion

  19. Modelling Brain Temperature and Perfusion for Cerebral Cooling

    NASA Astrophysics Data System (ADS)

    Blowers, Stephen; Valluri, Prashant; Marshall, Ian; Andrews, Peter; Harris, Bridget; Thrippleton, Michael

    2015-11-01

    Brain temperature relies heavily on two aspects: i) blood perfusion and porous heat transport through tissue and ii) blood flow and heat transfer through embedded arterial and venous vasculature. Moreover brain temperature cannot be measured directly unless highly invasive surgical procedures are used. A 3D two-phase fluid-porous model for mapping flow and temperature in brain is presented with arterial and venous vessels extracted from MRI scans. Heat generation through metabolism is also included. The model is robust and reveals flow and temperature maps in unprecedented 3D detail. However, the Karmen-Kozeny parameters of the porous (tissue) phase need to be optimised for expected perfusion profiles. In order to optimise the K-K parameters a reduced order two-phase model is developed where 1D vessels are created with a tree generation algorithm embedded inside a 3D porous domain. Results reveal that blood perfusion is a strong function of the porosity distribution in the tissue. We present a qualitative comparison between the simulated perfusion maps and those obtained clinically. We also present results studying the effect of scalp cooling on core brain temperature and preliminary results agree with those observed clinically.

  20. Intrahemispheric Perfusion in Chronic Stroke-Induced Aphasia

    PubMed Central

    Walenski, Matthew; Chen, YuFen; Caplan, David; Rapp, Brenda; Grunewald, Kristin; Nunez, Mia; Zinbarg, Richard; Parrish, Todd B.

    2017-01-01

    Stroke-induced alterations in cerebral blood flow (perfusion) may contribute to functional language impairments and recovery in chronic aphasia. Using MRI, we examined perfusion in the right and left hemispheres of 35 aphasic and 16 healthy control participants. Across 76 regions (38 per hemisphere), no significant between-subjects differences were found in the left, whereas blood flow in the right was increased in the aphasic compared to the control participants. Region-of-interest (ROI) analyses showed a varied pattern of hypo- and hyperperfused regions across hemispheres in the aphasic participants; however, there were no significant correlations between perfusion values and language abilities in these regions. These patterns may reflect autoregulatory changes in blood flow following stroke and/or increases in general cognitive effort, rather than maladaptive language processing. We also examined blood flow in perilesional tissue, finding the greatest hypoperfusion close to the lesion (within 0–6 mm), with greater hypoperfusion in this region compared to more distal regions. In addition, hypoperfusion in this region was significantly correlated with language impairment. These findings underscore the need to consider cerebral perfusion as a factor contributing to language deficits in chronic aphasia as well as recovery of language function. PMID:28357141

  1. Uptake of Free Choline by Isolated Perfused Rat Liver

    NASA Astrophysics Data System (ADS)

    Zeisel, Steven H.; Story, David L.; Wurtman, Richard J.; Brunengraber, Henri

    1980-08-01

    The uptake of free choline by isolated perfused rat liver was characterized. A saturable uptake mechanism [Ka=0.17± 0.07 mM (SD); Vmax=0.84± 0.16\\ μ mol/min × g dry weight] and a nonsaturable mechanism (through which uptake is proportional to choline concentration in the perfusate) were identified. Most of the choline transported into hepatocytes was converted to betaine, phosphorylcholine, or lecithin. Free choline also accumulated within the intracellular space, suggesting that choline oxidase activity does not always limit choline's uptake by the liver.

  2. WE-B-BRD-00: MRI for Radiation Oncology

    SciTech Connect

    2015-06-15

    The use of MRI in radiation therapy is rapidly increasing. Applications vary from the MRI simulator, to the MRI fused with CT, and to the integrated MRI+RT system. Compared with the standard MRI QA, a broader scope of QA features has to be defined in order to maximize the benefits of using MRI in radiation therapy. These QA features include geometric fidelity, image registration, motion management, cross-system alignment, and hardware interference. Advanced MRI techniques require a specific type of QA, as they are being widely used in radiation therapy planning, dose calculations, post-implant dosimetry, and prognoses. A vigorous and adaptive QA program is crucial to defining the responsibility of the entire radiation therapy group and detecting deviations from the performance of high-quality treatment. As a drastic departure from CT simulation, MRI simulation requires changes in the work flow of treatment planning and image guidance. MRI guided radiotherapy platforms are being developed and commercialized to take the advantage of the advance in knowledge, technology and clinical experience. This symposium will from an educational perspective discuss the scope and specific issues related to MRI guided radiotherapy. Learning Objectives: Understand the difference between a standard and a radiotherapy-specific MRI QA program. Understand the effects of MRI artifacts (geometric distortion and motion) on radiotherapy. Understand advanced MRI techniques (ultrashort echo, fast MRI including dynamic MRI and 4DMRI, diffusion, perfusion, and MRS) and related QA. Understand the methods to prepare MRI for treatment planning (electron density assignment, multimodality image registration, segmentation and motion management). Current status of MRI guided treatment platforms. Dr. Jihong Wang has a research grant with Elekta-MRL project. Dr. Ke Sheng receives research grants from Varian Medical systems.

  3. Cerebral-Body Perfusion Model

    DTIC Science & Technology

    1990-07-01

    compared to the 0.5g curve) fall in flow. Fig. 9b, showing the 5g case, strongly suggests a possible, so-called, " luxury perfusion ", in which natural...as the luxury perfusion situation which bypasses the flow with the nutrients it carries (through newly opened collaterals) and result in a "blackout...89-0054 CEREBRAL-BODY PERFUSION MODEL S. Sorek’, J. Bear2, and M., Feinsod3 in Collaboration with K. Allen4, L. Bunt5 and S. Ben-IHaiM6 July 1990

  4. Integration of DCE-MRI and DW-MRI Quantitative Parameters for Breast Lesion Classification

    PubMed Central

    Fusco, Roberta; Sansone, Mario; Filice, Salvatore; Granata, Vincenza; Catalano, Orlando; Amato, Daniela Maria; Di Bonito, Maurizio; D'Aiuto, Massimiliano; Capasso, Immacolata; Rinaldo, Massimo; Petrillo, Antonella

    2015-01-01

    Objective. The purpose of our study was to evaluate the diagnostic value of an imaging protocol combining dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted MRI (DW-MRI) in patients with suspicious breast lesions. Materials and Methods. A total of 31 breast lesions (15 malignant and 16 benign proved by histological examination) in 26 female patients were included in this study. For both DCE-MRI and DW-MRI model free and model based parameters were computed pixel by pixel on manually segmented ROIs. Statistical procedures included conventional linear analysis and more advanced techniques for classification of lesions in benign and malignant. Results. Our findings indicated no strong correlation between DCE-MRI and DW-MRI parameters. Results of classification analysis show that combining of DCE parameters or DW-MRI parameter, in comparison of single feature, does not yield a dramatic improvement of sensitivity and specificity of the two techniques alone. The best performance was obtained considering a full combination of all features. Moreover, the classification results combining all features are dominated by DCE-MRI features alone. Conclusion. The combination of DWI and DCE-MRI does not show a potential to dramatically increase the sensitivity and specificity of breast MRI. DCE-MRI alone gave the same performance as in combination with DW-MRI. PMID:26339597

  5. The interplay of T1- and T2-relaxation on T1-weighted MRI of hMSCs induced by Gd-DOTA-peptides.

    PubMed

    Cao, Limin; Li, Binbin; Yi, Peiwei; Zhang, Hailu; Dai, Jianwu; Tan, Bo; Deng, Zongwu

    2014-04-01

    Three Gd-DOTA-peptide complexes with different peptide sequence are synthesized and used as T1 contrast agent to label human mesenchymal stem cells (hMSCs) for magnetic resonance imaging study. The peptides include a universal cell penetrating peptide TAT, a linear MSC-specific peptide EM7, and a cyclic MSC-specific peptide CC9. A significant difference in labeling efficacy is observed between the Gd-DOTA-peptides as well as a control Dotarem. All Gd-DOTA-peptides as well as Dotarem induce significant increase in T1 relaxation rate which is in favor of T1-weighted MR imaging. Gd-DOTA-CC9 yields the maximum labeling efficacy but poor T1 contrast enhancement. Gd-DOTA-EM7 yields the minimum labeling efficacy but better T1 contrast enhancement. Gd-DOTA-TAT yields a similar labeling efficacy as Gd-DOTA-CC9 and similar T1 contrast enhancement as Gd-DOTA-EM7. The underlying mechanism that governs T1 contrast enhancement effect is discussed. Our results suggest that T1 contrast enhancement induced by Gd-DOTA-peptides depends not only on the introduced cellular Gd content, but more importantly on the effect that Gd-DOTA-peptides exert on the T1-relaxation and T2-relaxation processes/rates. Both T1 and particularly T2 relaxation rate have to be taken into account to interpret T1 contrast enhancement. In addition, the interpretation has to be based on cellular instead of aqueous longitudinal and transverse relaxivities of Gd-DOTA-peptides.

  6. Precise Characterization of the Penumbra Revealed by MRI: A Modified Photothrombotic Stroke Model Study

    PubMed Central

    Jiao, Yun; Yao, Hong-Hong; Chen, Yu-Chen; Yang, Jian; Ding, Jie; Yang, Xiang-Yu; Teng, Gao-Jun

    2016-01-01

    Aims To precisely characterize the penumbra by MRI based on a modified photothrombotic stroke mouse model. Methods The proximal middle cerebral artery was occluded by a convenient laser system in conjunction with an intravenous injection of Rose Bengal in mice. And the suture MCAO model was performed in seven mice as a comparison of the reproducibility. One hour after occlusion, the penumbra was defined in six random photothrombotic stroke mice by mismatch between perfusion-weighted imaging and the apparent diffusion coefficient map on a home-made workstation. After imaging, three random mice of them were chosen to perform the reperfusion surgery. And the other three mice were sacrificed to stain for several potential penumbra markers, such as c-fos and heart shock protein 90. In the remaining mice, the evolution of the lesions was detected on the apparent diffusion coefficient map, diffusion-weighted imaging and T2-weighted imaging at 1, 3, 6, 12 and 24 hours. After evaluating the neurological deficit scores, the brains were sectioned and stained by triphenyltetrazolium chloride and Nissl. Results The mice subjected to photothrombosis showed significant behavioral deficits. One hour after occlusion, the low perfusion areas on the perfusion-weighted imaging interlaced with the hypointense areas on the apparent diffusion coefficient map, demonstrating that the penumbra was located both surrounding and inside the lesions. This phenomenon was subsequently confirmed by the c-fos and heart shock protein 90 staining. The final T2-weighted images of the mice subjected to the reperfusion surgery were also consistent with the penumbra images at one hour. At early stages, the lesions were clearly identified on the apparent diffusion coefficient map; the volumes of the lesions on the diffusion-weighted imaging and T2-weighted imaging did not reach a maximum until 12 hours. The coefficient of variation (CV) of the final lesions in the photothrombotic stroke mice was 21.7% (0

  7. Multiparametric MRI-based differentiation of WHO grade II/III glioma and WHO grade IV glioblastoma

    PubMed Central

    Wiestler, Benedikt; Kluge, Anne; Lukas, Mathias; Gempt, Jens; Ringel, Florian; Schlegel, Jürgen; Meyer, Bernhard; Zimmer, Claus; Förster, Stefan; Pyka, Thomas; Preibisch, Christine

    2016-01-01

    Non-invasive, imaging-based examination of glioma biology has received increasing attention in the past couple of years. To this end, the development and refinement of novel MRI techniques, reflecting underlying oncogenic processes such as hypoxia or angiogenesis, has greatly benefitted this research area. We have recently established a novel BOLD (blood oxygenation level dependent) based MRI method for the measurement of relative oxygen extraction fraction (rOEF) in glioma patients. In a set of 37 patients with newly diagnosed glioma, we assessed the performance of a machine learning model based on multiple MRI modalities including rOEF and perfusion imaging to predict WHO grade. An oblique random forest machine learning classifier using the entire feature vector as input yielded a five-fold cross-validated area under the curve of 0.944, with 34/37 patients correctly classified (accuracy 91.8%). The most important features in this classifier as per bootstrapped feature importance scores consisted of standard deviation of T1-weighted contrast enhanced signal, maximum rOEF value and cerebral blood volume (CBV) standard deviation. This study suggests that multimodal MRI information reflects underlying tumor biology, which is non-invasively detectable through integrative data analysis, and thus highlights the potential of such integrative approaches in the field of radiogenomics. PMID:27739434

  8. A New Coronary Model for MRI Perfusion Studies

    DTIC Science & Technology

    2007-11-02

    heart. The first results are obtained for low and high input flows in a normal heart. The last one is a simulation of an ischemic heart behavior. The...sectional area of the vessel. And, we assume that the resistance R to flow is given approximately by the Poiseuille law. The compliance C of a...description of the blood flow is used. The compartments taken into account are the arteries, capillaries, lymphatic and venous systems, extravascular

  9. Localized Spatio-Temporal Constraints for Accelerated CMR Perfusion

    PubMed Central

    Akçakaya, Mehmet; Basha, Tamer A.; Pflugi, Silvio; Foppa, Murilo; Kissinger, Kraig V.; Hauser, Thomas H.; Nezafat, Reza

    2013-01-01

    Purpose To develop and evaluate an image reconstruction technique for cardiac MRI (CMR)perfusion that utilizes localized spatio-temporal constraints. Methods CMR perfusion plays an important role in detecting myocardial ischemia in patients with coronary artery disease. Breath-hold k-t based image acceleration techniques are typically used in CMR perfusion for superior spatial/temporal resolution, and improved coverage. In this study, we propose a novel compressed sensing based image reconstruction technique for CMR perfusion, with applicability to free-breathing examinations. This technique uses local spatio-temporal constraints by regularizing image patches across a small number of dynamics. The technique is compared to conventional dynamic-by-dynamic reconstruction, and sparsity regularization using a temporal principal-component (pc) basis, as well as zerofilled data in multi-slice 2D and 3D CMR perfusion. Qualitative image scores are used (1=poor, 4=excellent) to evaluate the technique in 3D perfusion in 10 patients and 5 healthy subjects. On 4 healthy subjects, the proposed technique was also compared to a breath-hold multi-slice 2D acquisition with parallel imaging in terms of signal intensity curves. Results The proposed technique results in images that are superior in terms of spatial and temporal blurring compared to the other techniques, even in free-breathing datasets. The image scores indicate a significant improvement compared to other techniques in 3D perfusion (2.8±0.5 vs. 2.3±0.5 for x-pc regularization, 1.7±0.5 for dynamic-by-dynamic, 1.1±0.2 for zerofilled). Signal intensity curves indicate similar dynamics of uptake between the proposed method with a 3D acquisition and the breath-hold multi-slice 2D acquisition with parallel imaging. Conclusion The proposed reconstruction utilizes sparsity regularization based on localized information in both spatial and temporal domains for highly-accelerated CMR perfusion with potential utility in free

  10. Pulmonary ventilation/perfusion scan

    MedlinePlus

    ... JavaScript. A pulmonary ventilation/perfusion scan involves two nuclear scan tests to measure breathing (ventilation) and circulation ( ... In: Mettler FA, Guiberteau MJ, eds. Essentials of Nuclear Medicine Imaging . 6th ed. Philadelphia, PA: Elsevier Saunders; ...

  11. Portable MRI

    SciTech Connect

    Espy, Michelle A.

    2012-06-29

    This project proposes to: (1) provide the power of MRI to situations where it presently isn't available; (2) perform the engineering required to move from lab to a functional prototype; and (3) leverage significant existing infrastructure and capability in ultra-low field MRI. The reasons for doing this: (1) MRI is the most powerful tool for imaging soft-tissue (e.g. brain); (2) Billions don't have access due to cost or safety issues; (3) metal will heat/move in high magnetic fields; (4) Millions of cases of traumatic brain injury in US alone; (5) even more of non-traumatic brain injury; (6) (e.g. stroke, infection, chemical exposure); (7) Need for early diagnostic; (8) 'Signature' wound of recent conflicts; (9) 22% of injuries; (10) Implications for post-traumatic stress disorder; and (11) chronic traumatic encephalopathy.

  12. MRI (Magnetic Resonance Imaging)

    MedlinePlus

    ... and Procedures Medical Imaging MRI (Magnetic Resonance Imaging) MRI (Magnetic Resonance Imaging) Share Tweet Linkedin Pin it More sharing options ... usually given through an IV in the arm. MRI Research Programs at FDA Magnetic Resonance Imaging (MRI) ...

  13. MRI Safety during Pregnancy

    MedlinePlus

    ... News Physician Resources Professions Site Index A-Z MRI Safety During Pregnancy Magnetic resonance imaging (MRI) Illness ... during the exam? Contrast material MRI during pregnancy Magnetic resonance imaging (MRI) If you are pregnant and your doctor ...

  14. CAD of myocardial perfusion

    NASA Astrophysics Data System (ADS)

    Storm, Corstiaan J.; Slump, Cornelis H.

    2007-03-01

    Our purpose is in the automated evaluation of the physiological relevance of lesions in coronary angiograms. We aim to extract as much as possible quantitative information about the physiological condition of the heart from standard angiographic image sequences. Coronary angiography is still the gold standard for evaluating and diagnosing coronary abnormalities as it is able to locate precisely the coronary artery lesions. The dimensions of the stenosis can be assessed nowadays successfully with image processing based Quantitative Coronary Angiography (QCA) techniques. Our purpose is to assess the clinical relevance of the pertinent stenosis. We therefore analyze the myocardial perfusion as revealed in standard angiographic image sequences. In a Region-of-Interest (ROI) on the angiogram (without an overlaying major blood vessel) the contrast is measured as a function of time (the so-called time-density curve). The required hyperemic state of exercise is induced artificially by the injection of a vasodilator drug e.g. papaverine. In order to minimize motion artifacts we select based on the recorded ECG signal end-diastolic images in both a basal and a hyperemic run in the same projection to position the ROI. We present the development of the algorithms together with results of a small study of 20 patients which have been catheterized following the standard protocol.

  15. [MRI in subacromial pathology. Report of 20 cases].

    PubMed

    Poey, C; Fajadet, P; Pages, M; Chaffai, M A; Lassoued, S; Maquin, P; Fournie, A; Mansat, M; Railhac, J J

    1990-01-01

    The authors report the results of MRI performed in 20 patients presenting clinical symptoms of subacromial pathology. The MRI results are correlated to the results of arthrography or arthro CT scan and also to surgical results. MRI is an excellent technique if a precise protocol with T2 weighted images is respected in order to visualize tears or minor perforations of the supraspinatus muscle.

  16. Repeated diffusion MRI reveals earliest time point for stratification of radiotherapy response in brain metastases

    NASA Astrophysics Data System (ADS)

    Mahmood, Faisal; Johannesen, Helle H.; Geertsen, Poul; Hansen, Rasmus H.

    2017-04-01

    An imaging biomarker for early prediction of treatment response potentially provides a non-invasive tool for better prognostics and individualized management of the disease. Radiotherapy (RT) response is generally related to changes in gross tumor volume manifesting months later. In this prospective study we investigated the apparent diffusion coefficient (ADC), perfusion fraction and pseudo diffusion coefficient derived from diffusion weighted MRI as potential early biomarkers for radiotherapy response of brain metastases. It was a particular aim to assess the optimal time point for acquiring the DW-MRI scan during the course of treatment, since to our knowledge this important question has not been addressed directly in previous studies. Twenty-nine metastases (N  =  29) from twenty-one patients, treated with whole-brain fractionated external beam RT were analyzed. Patients were scanned with a 1 T MRI system to acquire DW-, T2*W-, T2W- and T1W scans, before start of RT, at each fraction and at follow up two to three months after RT. The DW-MRI parameters were derived using regions of interest based on high b-value images (b  =  800 s mm‑2). Both volumetric and RECIST criteria were applied for response evaluation. It was found that in non-responding metastases the mean ADC decreased and in responding metastases it increased. The volume based response proved to be far more consistently predictable by the ADC change found at fraction number 7 and later, compared to the linear response (RECIST). The perfusion fraction and pseudo diffusion coefficient did not show sufficient prognostic value with either response assessment criteria. In conclusion this study shows that the ADC derived using high b-values may be a reliable biomarker for early assessment of radiotherapy response for brain metastases patients. The earliest response stratification can be achieved using two DW-MRI scans, one pre-treatment and one at treatment day 7–9 (equivalent to 21

  17. Multiparametric Functional MRI: A Tool to Uncover Subtle Changes following Allogeneic Renal Transplantation

    PubMed Central

    Notohamiprodjo, Mike; Kalnins, Aivars; Andrassy, Martin; Kolb, Manuel; Ehle, Benjamin; Mueller, Susanna; Thomas, Michael N.; Werner, Jens; Guba, Markus; Nikolaou, Konstantin; Andrassy, Joachim

    2016-01-01

    Purpose To investigate multiparametric functional MRI to characterize acute rejection in a murine allogeneic renal transplant model and evaluate the effect of novel therapeutics. Material and Methods We performed allogeneic and syngeneic orthotopic transplantations (Balb/c to C57Bl/6 and C57Bl/6 to C57Bl/6). Allogeneic Groups (n = 5) were either treated with the anti-CCL2-Spiegelmer (mNOX-E36) in monotherapy or in combination with low doses of Ciclosporin-A (10mg/kgBW/d) for 10 days. Controls received equivalent doses of a non-functional spiegelmer (revmNOX-E36) or low dose Ciclosporin-A. Diffusion-weighted (DWI) and Dynamic-contrast-enhanced (DCE-) MRI-scans were performed using a clinical 3T-scanner. DWI analysis (b-values from 0–800 s/mm2) was performed mono- and biexponentially, while DCE-MRI was assessed with deconvolution analysis. Therapy effects were assessed ex vivo with histopathology, immunohistochemistry and RT-PCR. Statistical analysis was performed with unpaired t-tests and Spearman´s correlation coefficient. Results DWI showed a significant diffusion restriction in allogeneic compared to syngeneic transplants (ADC: 0.63±0.08 vs. 1.29±0.12 mm2/s*103) with decreasing diffusion restriction under therapy. DCE-MRI showed restored organ perfusion under Ciclosporin A alone and combination therapy (Plasma Flow: 43.43±12.49; 38.75±7.53ml/100ml/min) compared to syngeneic controls (51.03±12.49ml/100ml/min). Ex vivo analysis showed reduced monocytic infiltrates, attenuated levels of inflammatory cytokines under mNOX-E36 monotherapy with an additive effect of low dose Ciclosporin A. There was a significant (p<0.05) negative correlation between ADC and interstitial inflammation (r = -0.73) or macrophage infiltration (r = -0.81) and between organ perfusion and intimal arteritis (r = -0.63). Conclusion Multiparametric functional MRI is suited to detect renal allograft rejection in an experimental murine model and allows to characterize effects of

  18. Gross morphology and morphometric sequelae in the hippocampus, fornix, and corpus callosum of patients with severe non-missile traumatic brain injury without macroscopically detectable lesions: a T1 weighted MRI study

    PubMed Central

    Tomaiuolo, F; Carlesimo, G; Di, P; Petrides, M; Fera, F; Bonanni, R; Formisano, R; Pasqualetti, P; Caltagirone, C

    2004-01-01

    Objective: The gross morphology and morphometry of the hippocampus, fornix, and corpus callosum in patients with severe non-missile traumatic brain injury (nmTBI) without obvious neuroradiological lesions was examined and the volumes of these structures were correlated with performance on memory tests. In addition, the predictability of the length of coma from the selected anatomical volumes was examined. Method: High spatial resolution T1 weighted MRI scans of the brain (1 mm3) and neuropsychological evaluations with standardised tests were performed at least 3 months after trauma in 19 patients. Results: In comparison with control subjects matched in terms of gender and age, volume reduction in the hippocampus, fornix, and corpus callosum of the nmTBI patients was quantitatively significant. The length of coma correlated with the volume reduction in the corpus callosum. Immediate free recall of word lists correlated with the volume of the fornix and the corpus callosum. Delayed recall of word lists and immediate recall of the Rey figure both correlated with the volume of the fornix. Delayed recall of the Rey figure correlated with the volume of the fornix and the right hippocampus. Conclusion: These findings demonstrate that in severe nmTBI without obvious neuroradiological lesions there is a clear hippocampal, fornix, and callosal volume reduction. The length of coma predicts the callosal volume reduction, which could be considered a marker of the severity of axonal loss. A few memory test scores correlated with the volumes of the selected anatomical structures. This relationship with memory performance may reflect the diffuse nature of the damage, leading to the disruption of neural circuits at multiple levels and the progressive neural degeneration occurring in TBI. PMID:15314123

  19. Synergistic Effects of Hemoglobin and Tumor Perfusion on Tumor Control and Survival in Cervical Cancer

    SciTech Connect

    Mayr, Nina A. Wang, Jian Z.; Zhang Dongqing; Montebello, Joseph F.; Grecula, John C.; Lo, Simon S.; Fowler, Jeffery M.; Yuh, William T.C.

    2009-08-01

    Purpose: The tumor oxygenation status is likely influenced by two major factors: local tumor blood supply (tumor perfusion) and its systemic oxygen carrier, hemoglobin (Hgb). Each has been independently shown to affect the radiotherapy (RT) outcome in cervical cancer. This study assessed the effect of local tumor perfusion, systemic Hgb levels, and their combination on the treatment outcome in cervical cancer. Methods and Materials: A total of 88 patients with cervical cancer, Stage IB2-IVA, who were treated with RT/chemotherapy, underwent serial dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) before RT, at 20-22 Gy, and at 45-50 Gy. The DCE-MRI perfusion parameters, mean and lowest 10th percentile of the signal intensity distribution in the tumor pixels, and the Hgb levels, including pre-RT, nadir, and mean Hgb (average of weekly Hgb during RT), were correlated with local control and disease-specific survival. The median follow-up was 4.6 years. Results: Local recurrence predominated in the group with both a low mean Hgb (<11.2 g/dL) and low perfusion (lowest 10th percentile of signal intensity <2.0 at 20-22 Gy), with a 5-year local control rate of 60% vs. 90% for all other groups (p = .001) and a disease-specific survival rate of 41% vs. 72% (p = .008), respectively. In the group with both high mean Hgb and high perfusion, the 5-year local control rate and disease-specific survival rate was 100% and 78%, respectively. Conclusion: These results suggest that the compounded effects of Hgb level and tumor perfusion during RT influence the radioresponsiveness and survival in cervical cancer patients. The outcome was worst when both were impaired. The management of Hgb may be particularly important in patients with low tumor perfusion.

  20. Battlefield MRI

    DOE PAGES

    Espy, Michelle

    2015-06-01

    Magnetic Resonance Imaging is the best method for non-invasive imaging of soft tissue anatomy, saving countless lives each year. It is regarded as the gold standard for diagnosis of mild to moderate traumatic brain injuries. Furthermore, conventional MRI relies on very high, fixed strength magnetic fields (> 1.5 T) with parts-per-million homogeneity, which requires very large and expensive magnets.

  1. Multiparametric Breast MRI of Breast Cancer

    PubMed Central

    Rahbar, Habib; Partridge, Savannah C.

    2015-01-01

    Synopsis Breast MRI has increased in popularity over the past two decades due to evidence for its high sensitivity for cancer detection. Current clinical MRI approaches rely on the use of a dynamic contrast enhanced (DCE-MRI) acquisition that facilitates morphologic and semi-quantitative kinetic assessments of breast lesions. The use of more functional and quantitative parameters, such as pharmacokinetic features from high temporal resolution DCE-MRI, apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM) on diffusion weighted MRI, and choline concentrations on MR spectroscopy, hold promise to broaden the utility of MRI and improve its specificity. However, due to wide variations in approach among centers for measuring these parameters and the considerable technical challenges, robust multicenter data supporting their routine use is not yet available, limiting current applications of many of these tools to research purposes. PMID:26613883

  2. Sodium MRI.

    PubMed

    Ouwerkerk, Ronald

    2011-01-01

    Sodium ((23)Na) imaging has a place somewhere between (1)H-MRI and MR spectroscopy (MRS). Like MRS it potentially provides information on metabolic processes, but only one single resonance of ionic (23)Na is observed. Therefore pulse sequences do not need to code for a chemical shift dimension, allowing (23)Na images to be obtained at high resolutions as compared to MRS. In this chapter the biological significance of sodium in the brain will be discussed, as well as methods for observing it with (23)Na-MRI. Many vital cellular processes and interactions in excitable tissues depend on the maintenance of a low intracellular and high extracellular sodium concentration. Healthy cells maintain this concentration gradient at the cost of energy. Leaky cell membranes or an impaired energy metabolism immediately leads to an increase in cytosolic total tissue sodium. This makes sodium a biomarker for ischemia, cancer, excessive tissue activation, or tissue damage as might be caused by ablation therapy. Special techniques allow quantification of tissue sodium for the monitoring of disease or therapy in longitudinal studies or preferential observation of the intracellular component of the tissue sodium. New methods and high-field magnet technology provide new opportunities for (23)Na-MRI in clinical and biomedical research.

  3. Viable neurons with luxury perfusion in hydrocephalus.

    PubMed

    Wong, C Y; Luciano, M G; MacIntyre, W J; Brunken, R C; Hahn, J F; Go, R T

    1997-09-01

    A woman with hydrocephalus due to aqueductal stenosis had functional imaging of cerebral perfusion and metabolism to demonstrate the effects of endoscopic third ventriculostomy--a new form of internal surgical shunting. Technetium-99m-ECD SPECT and 18F-FDG PET showed regional luxury perfusion at the left frontal region. Three months after a successful third ventriculostomy, a repeated imaging of cerebral perfusion and metabolism showed resolution of luxury perfusion and global improvement of both perfusion and metabolism. This concurred with postoperative clinical improvement. The paired imaging of cerebral perfusion and metabolism provides more information than just imaging perfusion or metabolism. Thus, the detection of perfusion and metabolism mismatch may open a new window of opportunity for surgical intervention.

  4. Diffusion MRI in the heart

    PubMed Central

    Mekkaoui, Choukri; Reese, Timothy G.; Jackowski, Marcel P.; Bhat, Himanshu

    2015-01-01

    Diffusion MRI provides unique information on the structure, organization, and integrity of the myocardium without the need for exogenous contrast agents. Diffusion MRI in the heart, however, has proven technically challenging because of the intrinsic non‐rigid deformation during the cardiac cycle, displacement of the myocardium due to respiratory motion, signal inhomogeneity within the thorax, and short transverse relaxation times. Recently developed accelerated diffusion‐weighted MR acquisition sequences combined with advanced post‐processing techniques have improved the accuracy and efficiency of diffusion MRI in the myocardium. In this review, we describe the solutions and approaches that have been developed to enable diffusion MRI of the heart in vivo, including a dual‐gated stimulated echo approach, a velocity‐ (M 1) or an acceleration‐ (M 2) compensated pulsed gradient spin echo approach, and the use of principal component analysis filtering. The structure of the myocardium and the application of these techniques in ischemic heart disease are also briefly reviewed. The advent of clinical MR systems with stronger gradients will likely facilitate the translation of cardiac diffusion MRI into clinical use. The addition of diffusion MRI to the well‐established set of cardiovascular imaging techniques should lead to new and complementary approaches for the diagnosis and evaluation of patients with heart disease. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd. PMID:26484848

  5. MRI Biomarkers in Oncology Clinical Trials

    PubMed Central

    Abramson, Richard G.; Arlinghaus, Lori; Dula, Adrienne; Quarles, C. Chad; Stokes, Ashley; Weis, Jared; Whisenant, Jennifer; Chekmenev, Eduard Y.; Zhukov, Igor; Williams, Jason; Yankeelov, Thomas

    2015-01-01

    Quantitative magnetic resonance imaging (MRI) techniques have the ability to quantitatively report various pathophysiological processes associated with cancer. These measures have been shown to provide complementary information to that typically obtained from standard morphologically based criteria (e.g., size) and, furthermore, have been shown to outperform sized based measures in certain applications. In this review, we discuss eight areas of quantitative MRI that are either currently employed in clinical trials, or are emerging as promising techniques for both diagnosing cancer as well as assessing—or even predicting—the response of cancer to various therapies. The currently employed methods include the response evaluation criteria in solid tumors (RECIST), dynamic susceptibility MRI (DSC-MRI), dynamic contrast enhanced MRI (DCE-MRI), and diffusion weighted imaging (DWI). The emerging techniques covered are chemical exchange saturation transfer MRI (CEST-MRI), elastography, hyperpolarized MRI, and multi-parameter MRI. After a brief introduction to each technique, we present a small number of illustrative applications before noting the existing limitations of each method and what must be done to move each to more routine clinical application. PMID:26613873

  6. Dopaminergic Therapy Modulates Cortical Perfusion in Parkinson Disease With and Without Dementia According to Arterial Spin Labeled Perfusion Magnetic Resonance Imaging.

    PubMed

    Lin, Wei-Che; Chen, Pei-Chin; Huang, Yung-Cheng; Tsai, Nai-Wen; Chen, Hsiu-Ling; Wang, Hung-Chen; Lin, Tsu-Kung; Chou, Kun-Hsien; Chen, Meng-Hsiang; Chen, Yi-Wen; Lu, Cheng-Hsien

    2016-02-01

    Arterial spin labeling (ASL) magnetic resonance imaging analyses allow for the quantification of altered cerebral blood flow, and provide a novel means of examining the impact of dopaminergic treatments. The authors examined the cerebral perfusion differences among 17 Parkinson disease (PD) patients, 17 PD with dementia (PDD) patients, and 17 healthy controls and used ASL-MRI to assess the effects of dopaminergic therapies on perfusion in the patients. The authors demonstrated progressive widespread cortical hypoperfusion in PD and PDD and robust effects for the dopaminergic therapies. Specifically, dopaminergic medications further decreased frontal lobe and cerebellum perfusion in the PD and PDD groups, respectively. These patterns of hypoperfusion could be related to cognitive dysfunctions and disease severity. Furthermore, desensitization to dopaminergic therapies in terms of cortical perfusion was found as the disease progressed, supporting the concept that long-term therapies are associated with the therapeutic window narrowing. The highly sensitive pharmaceutical response of ASL allows clinicians and researchers to easily and effectively quantify the absolute perfusion status, which might prove helpful for therapeutic planning.

  7. Tracer kinetic analysis of dynamic contrast-enhanced MRI and CT bladder cancer data: A preliminary comparison to assess the magnitude of water exchange effects.

    PubMed

    Bains, Lauren J; McGrath, Deirdre M; Naish, Josephine H; Cheung, Susan; Watson, Yvonne; Taylor, M Ben; Logue, John P; Parker, Geoffrey J M; Waterton, John C; Buckley, David L

    2010-08-01

    The purpose of this study was to determine the impact of water exchange on tracer kinetic parameter estimates derived from T(1)-weighted dynamic contrast-enhanced (DCE)-MRI data using a direct quantitative comparison with DCE-CT. Data were acquired from 12 patients with bladder cancer who underwent DCE-CT followed by DCE-MRI within a week. A two-compartment tracer kinetic model was fitted to the CT data, and two versions of the same model with modifications to account for the fast exchange and no exchange limits of water exchange were fitted to the MR data. The two-compartment tracer kinetic model provided estimates of the fractional plasma volume (v(p)), the extravascular extracellular space fraction (v(e)), plasma perfusion (F(p)), and the microvascular permeability surface area product. Our findings suggest that DCE-CT is an appropriate reference for DCE-MRI in bladder cancers as the only significant difference found between CT and MR parameter estimates were the no exchange limit estimates of v(p) (P = 0.002). These results suggest that although water exchange between the intracellular and extravascular-extracellular space has a negligible effect on DCE-MRI, vascular-extravascular-extracellular space water exchange may be more important.

  8. Perfusion decellularization of whole organs.

    PubMed

    Guyette, Jacques P; Gilpin, Sarah E; Charest, Jonathan M; Tapias, Luis F; Ren, Xi; Ott, Harald C

    2014-01-01

    The native extracellular matrix (ECM) outlines the architecture of organs and tissues. It provides a unique niche of composition and form, which serves as a foundational scaffold that supports organ-specific cell types and enables normal organ function. Here we describe a standard process for pressure-controlled perfusion decellularization of whole organs for generating acellular 3D scaffolds with preserved ECM protein content, architecture and perfusable vascular conduits. By applying antegrade perfusion of detergents and subsequent washes to arterial vasculature at low physiological pressures, successful decellularization of complex organs (i.e., hearts, lungs and kidneys) can be performed. By using appropriate modifications, pressure-controlled perfusion decellularization can be achieved in small-animal experimental models (rat organs, 4-5 d) and scaled to clinically relevant models (porcine and human organs, 12-14 d). Combining the unique structural and biochemical properties of native acellular scaffolds with subsequent recellularization techniques offers a novel platform for organ engineering and regeneration, for experimentation ex vivo and potential clinical application in vivo.

  9. 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

  10. Activity-induced manganese-dependent MRI (AIM-MRI) and functional MRI in awake rabbits during somatosensory stimulation

    PubMed Central

    Schroeder, Matthew P.; Weiss, Craig; Procissi, Daniel; Wang, Lei; Disterhoft, John F.

    2015-01-01

    Activity-induced manganese-dependent MRI (AIM-MRI) is a powerful tool to track system-wide neural activity using high resolution, quantitative T1-weighted MRI in animal models and has significant advantages for investigating neural activity over other modalities including BOLD fMRI. With AIM-MRI, Mn2+ ions enter neurons via voltage-gated calcium channels preferentially active during the time of experimental exposure. A broad range of AIM-MRI studies using different species studying different phenomena have been performed, but few of these studies provide a systematic evaluation of the factors influencing the detection of Mn2+ such as dosage and the temporal characteristics of Mn2+ uptake. We identified an optimal dose of Mn2+ (25 mg/kg, s.c.) in order to characterize the time-course of Mn2+ accumulation in active neural regions in the rabbit. T1-weighted MRI and functional MRI were collected 0–3, 6–9, and 24–27 h post-Mn2+ injection while the vibrissae on the right side were vibrated. Significant BOLD activation in the left somatosensory (SS) cortex and left ventral posteromedial (VPM) thalamic nucleus was detected during whisker vibration. T1-weighted signal intensities were extracted from these regions, their corresponding contralateral regions and the visual cortex (to serve as controls). A significant elevation in T1-weighted signal intensity in the left SS cortex (relative to right)was evident 6–9 and 24–27 h post-Mn2+ injection while the left VPM thalamus showed a significant enhancement (relative to the right) only during the 24–27 h session. Visual cortex showed no hemispheric difference at any timepoint. Our results suggest that studies employing AIM-MRI would benefit by conducting experimental manipulations 6–24 h after subcutaneous MnCl2 injections to optimize the concentration of contrast agent in the regions active during the exposure. PMID:26589332

  11. MRI of the lung: state of the art.

    PubMed

    Wielpütz, Mark; Kauczor, Hans-Ulrich

    2012-01-01

    Magnetic resonance imaging (MRI) of the lung is technically challenging due to the low proton density and fast signal decay of the lung parenchyma itself. Additional challenges consist of tissue loss, hyperinflation, and hypoxic hypoperfusion, e.g., in emphysema, a so-called "minus-pathology". However, pathological changes resulting in an increase of tissue ("plus-pathology"), such as atelectases, nodules, infiltrates, mucus, or pleural effusion, are easily depicted with high diagnostic accuracy. Although MRI is inferior or at best equal to multi-detector computed tomography (MDCT) for the detection of subtle morphological features, MRI now offers an increasing spectrum of functional imaging techniques such as perfusion assessment and measurement of ventilation and respiratory mechanics that are superior to what is possible with MDCT. Without putting patients at risk with ionizing radiation, repeated examinations allow for the evaluation of the course of lung disease and monitoring of the therapeutic response through quantitative imaging, providing a level of functional detail that cannot be obtained by any other single imaging modality. As such, MRI will likely be used for clinical applications beyond morphological imaging for many lung diseases. In this article, we review the technical aspects and protocol suggestions for chest MRI and discuss the role of MRI in the evaluation of nodules and masses, airway disease, respiratory mechanics, ventilation, perfusion and hemodynamics, and pulmonary vasculature.

  12. Dependence of Brain Intravoxel Incoherent Motion Perfusion Parameters on the Cardiac Cycle

    PubMed Central

    Federau, Christian; Hagmann, Patric; Maeder, Philippe; Müller, Markus; Meuli, Reto; Stuber, Matthias; O’Brien, Kieran

    2013-01-01

    Measurement of microvascular perfusion with Intravoxel Incoherent Motion (IVIM) MRI is gaining interest. Yet, the physiological influences on the IVIM perfusion parameters (“pseudo-diffusion” coefficient D*, perfusion fraction f, and flow related parameter fD*) remain insufficiently characterized. In this article, we hypothesize that D* and fD*, which depend on blood speed, should vary during the cardiac cycle. We extended the IVIM model to include time dependence of D* = D*(t), and demonstrate in the healthy human brain that both parameters D* and fD* are significantly larger during systole than diastole, while the diffusion coefficient D and f do not vary significantly. The results non-invasively demonstrate the pulsatility of the brain’s microvasculature. PMID:24023649

  13. Thallium-201 myocardial perfusion imaging in myocarditis

    SciTech Connect

    Tamaki, N.; Yonekura, Y.; Kadota, K.; Kambara, H.; Torizuka, K.

    1985-08-01

    TI-201 myocardial perfusion imaging was performed in six patients with clinically documented myocarditis. Each case manifested electrocardiographic abnormalities with elevation of serum cardiac enzymes and no significant stenosis of the coronary arteries observed on angiogram. Resting TI-201 images were visually assessed by three observers. Focal perfusion defects were observed in three cases (50%), among which two showed multiple perfusion defects. Emission computed tomography using TI-201 clearly delineated multifocal lesions in the first case. On the other hand, no significant perfusion defects were noted in the remaining three cases. Thus, myocarditis should be considered as one of the disease entities that may produce perfusion defects on TI-201 myocardial imaging.

  14. Imaging acute ischemic tissue acidosis with pH-sensitive endogenous amide proton transfer (APT) MRI - Correction of tissue relaxation and concomitant RF irradiation effects toward mapping quantitative cerebral tissue pH

    PubMed Central

    Sun, Phillip Zhe; Wang, Enfeng; Cheung, Jerry S

    2011-01-01

    Amide proton transfer (APT) MRI is sensitive to ischemic tissue acidosis and has been increasingly used as a research tool to investigate disrupted tissue metabolism during acute stroke. However, magnetization transfer asymmetry (MTRasym) analysis is often used for calculating APT contrast, which only provides pH-weighted images. In addition to pH- dependent APT contrast, in vivo MTRasym is subject to a baseline shift (ΔMTR′asym) attributable to the slightly asymmetric magnetization transfer (MT) effect. Additionally, APT contrast approximately scales with T1 relaxation time. Tissue relaxation time may also affect the experimentally obtainable APT contrast via saturation efficiency and RF spillover effects. In this study, we acquired perfusion, diffusion, relaxation and pH-weighted APT MRI data, and spectroscopy (MRS) in an animal model of acute ischemic stroke. We modeled in vivo MTRasym as a superposition of pH-dependent APT contrast and a baseline shift ΔMTR′asym (i.e., MTRasym=APTR(pH) + ΔMTR′asym), and quantified tissue pH. We found pH of the contralateral normal tissue to be 7.03 ± 0.05 and the ipsilateral ischemic tissue pH was 6.44 ± 0.24, which correlated with tissue perfusion and diffusion rates. In summary, our study established an endogenous and quantitative pH imaging technique for improved characterization of ischemic tissue acidification and metabolism disruption. PMID:22178815

  15. Does machine perfusion decrease ischemia reperfusion injury?

    PubMed

    Bon, D; Delpech, P-O; Chatauret, N; Hauet, T; Badet, L; Barrou, B

    2014-06-01

    In 1990's, use of machine perfusion for organ preservation has been abandoned because of improvement of preservation solutions, efficient without perfusion, easy to use and cheaper. Since the last 15 years, a renewed interest for machine perfusion emerged based on studies performed on preclinical model and seems to make consensus in case of expanded criteria donors or deceased after cardiac death donations. We present relevant studies highlighted the efficiency of preservation with hypothermic machine perfusion compared to static cold storage. Machines for organ preservation being in constant evolution, we also summarized recent developments included direct oxygenation of the perfusat. Machine perfusion technology also enables organ reconditioning during the last hours of preservation through a short period of perfusion on hypothermia, subnormothermia or normothermia. We present significant or low advantages for machine perfusion against ischemia reperfusion injuries regarding at least one primary parameter: risk of DFG, organ function or graft survival.

  16. Use of Cationized Ferritin Nanoparticles to Measure Renal Glomerular Microstructure with MRI.

    PubMed

    Bennett, Kevin M; Beeman, Scott C; Baldelomar, Edwin J; Zhang, Min; Wu, Teresa; Hann, Bradley D; Bertram, John F; Charlton, Jennifer R

    2016-01-01

    Magnetic resonance imaging (MRI) is becoming important for whole-kidney assessment of glomerular morphology, both in vivo and ex vivo. MRI-based renal morphological measurements can be made in intact organs and allow direct measurements of every perfused glomerulus. Cationic ferritin (CF) is used as a superparamagnetic contrast agent for MRI. CF binds to the glomerular basement membrane after intravenous injection, allowing direct, whole-kidney measurements of glomerular number, volume, and volume distribution. Here we describe the production, testing, and use of CF as an MRI contrast agent for quantitative glomerular morphology in intact mouse, rat, and human kidneys.

  17. A brief report on MRI investigation of experimental traumatic brain injury

    PubMed Central

    Duong, Timothy Q.; Watts, Lora T.

    2016-01-01

    Traumatic brain injury is a major cause of death and disability. This is a brief report based on a symposium presentation to the 2014 Chinese Neurotrauma Association Meeting in San Francisco, USA. It covers the work from our laboratory in applying multimodal MRI to study experimental traumatic brain injury in rats with comparisons made to behavioral tests and histology. MRI protocols include structural, perfusion, manganese-enhanced, diffusion-tensor MRI, and MRI of blood-brain barrier integrity and cerebrovascular reactivity. PMID:26981069

  18. Fragile X syndrome and cerebral perfusion abnormalities: single-photon emission computed tomographic study.

    PubMed

    Kabakus, Nimet; Aydin, Mustafa; Akin, Haluk; Balci, Tansel Ansal; Kurt, Abdullah; Kekilli, Ersoy

    2006-12-01

    Fragile X syndrome is an inherited disorder caused by a defective gene on the X chromosome. It is associated with developmental or behavioral symptoms and various degrees of mental retardation. Morphologic abnormalities and altered perfusion of various brain areas can underlie these functional disturbances. The aim of this study was to investigate the cerebral perfusion state in patients with fragile X syndrome using single-photon emission computed tomography (SPECT). Structural and functional assessment was also performed by magnetic resonance imaging (MRI) and electroencephalography (EEG). Eight boys with cytogenetically confirmed fragile X syndrome (mean age 8.8 +/- 4.4 years, range 5-18 years), were included. All patients had mental retardation, with a mean IQ of 58.9 +/- 8.8 (range 40-68), and additional neurobehavioral symptoms. SPECT revealed cerebral perfusion abnormalities in six patients (75%), most commonly in the frontoparietotemporal area and prominent in the right hemisphere. The SPECT and EEG findings were concordant: hypoperfused areas in SPECT corresponded to regions of persistent slow-wave paroxysms on EEG. On the other hand, cranial MRI was abnormal qualitatively only in two patients (25%) showing cerebellar and vermal hypoplasia and cerebral hemispheric asymmetry. Our results indicate that cerebral perfusion abnormalities, which are correlated with electrophysiologic findings but not necessarily with anatomic abnormalities, can underlie the pathogenesis of the clinical findings observed in fragile X syndrome.

  19. A New Apparatus and Surgical Technique for the Dual Perfusion of Human Tumor Xenografts in Situ in Nude Rats

    PubMed Central

    Dauchy, Robert T; Dauchy, Erin M; Mao, Lulu; Belancio, Victoria P; Hill, Steven M; Blask, David E

    2012-01-01

    We present a new perfusion system and surgical technique for simultaneous perfusion of 2 tissue-isolated human cancer xenografts in nude rats by using donor blood that preserves a continuous flow. Adult, athymic nude rats (Hsd:RH-Foxn1rnu) were implanted with HeLa human cervical or HT29 colon adenocarcinomas and grown as tissue-isolated xenografts. When tumors reached an estimated weight of 5 to 6 g, rats were prepared for perfusion with donor blood and arteriovenous measurements. The surgical procedure required approximately 20 min to complete for each tumor, and tumors were perfused for a period of 150 min. Results showed that tumor venous blood flow, glucose uptake, lactic acid release, O2 uptake and CO2 production, uptake of total fatty acid and linoleic acid and conversion to the mitogen 13-HODE, cAMP levels, and activation of several marker kinases were all well within the normal physiologic, metabolic, and signaling parameters characteristic of individually perfused xenografts. This new perfusion system and technique reduced procedure time by more than 50%. These findings demonstrate that 2 human tumors can be perfused simultaneously in situ or ex vivo by using either rodent or human blood and suggest that the system may also be adapted for use in the dual perfusion of other organs. Advantages of this dual perfusion technique include decreased anesthesia time, decreased surgical manipulation, and increased efficiency, thereby potentially reducing the numbers of laboratory animals required for scientific investigations. PMID:22546915

  20. Longitudinal MRI Evaluation of Intracranial Development and Vascular Characteristics of Breast Cancer Brain Metastases in a Mouse Model

    PubMed Central

    Zhou, Heling; Chen, Min; Zhao, Dawen

    2013-01-01

    Longitudinal MRI was applied to monitor intracranial initiation and development of brain metastases and assess tumor vascular volume and permeability in a mouse model of breast cancer brain metastases. Using a 9.4T system, high resolution anatomic MRI and dynamic susceptibility contrast (DSC) perfusion MRI were acquired at different time points after an intracardiac injection of brain-tropic breast cancer MDA-MB231BR-EGFP cells. Three weeks post injection, multifocal brain metastases were first observed with hyperintensity on T2-weighted images, but isointensity on T1-weighted post contrast images, indicating that blood-tumor-barrier (BTB) at early stage of brain metastases was impermeable. Follow-up MRI revealed intracranial tumor growth and increased number of metastases that distributed throughout the whole brain. At the last scan on week 5, T1-weighted post contrast images detected BTB disruption in 160 (34%) of a total of 464 brain metastases. Enhancement in some of the metastases was only seen in partial regions of the tumor, suggesting intratumoral heterogeneity of BTB disruption. DSC MRI measurements of relative cerebral blood volume (rCBV) showed that rCBV of brain metastases was significantly lower (mean  = 0.89±0.03) than that of contralateral normal brain (mean  = 1.00±0.03; p<0.005). Intriguingly, longitudinal measurements revealed that rCBV of individual metastases at early stage was similar to, but became significantly lower than that of contralateral normal brain with tumor growth (p<0.05). The rCBV data were concordant with histological analysis of microvascular density (MVD). Moreover, comprehensive analysis suggested no significant correlation among tumor size, rCBV and BTB permeability. In conclusion, longitudinal MRI provides non-invasive in vivo assessments of spatial and temporal development of brain metastases and their vascular volume and permeability. The characteristic rCBV of brain metastases may have a diagnostic value. PMID

  1. Competitive advantage of PET/MRI.

    PubMed

    Jadvar, Hossein; Colletti, Patrick M

    2014-01-01

    Multimodality imaging has made great strides in the imaging evaluation of patients with a variety of diseases. Positron emission tomography/computed tomography (PET/CT) is now established as the imaging modality of choice in many clinical conditions, particularly in oncology. While the initial development of combined PET/magnetic resonance imaging (PET/MRI) was in the preclinical arena, hybrid PET/MR scanners are now available for clinical use. PET/MRI combines the unique features of MRI including excellent soft tissue contrast, diffusion-weighted imaging, dynamic contrast-enhanced imaging, fMRI and other specialized sequences as well as MR spectroscopy with the quantitative physiologic information that is provided by PET. Most evidence for the potential clinical utility of PET/MRI is based on studies performed with side-by-side comparison or software-fused MRI and PET images. Data on distinctive utility of hybrid PET/MRI are rapidly emerging. There are potential competitive advantages of PET/MRI over PET/CT. In general, PET/MRI may be preferred over PET/CT where the unique features of MRI provide more robust imaging evaluation in certain clinical settings. The exact role and potential utility of simultaneous data acquisition in specific research and clinical settings will need to be defined. It may be that simultaneous PET/MRI will be best suited for clinical situations that are disease-specific, organ-specific, related to diseases of the children or in those patients undergoing repeated imaging for whom cumulative radiation dose must be kept as low as reasonably achievable. PET/MRI also offers interesting opportunities for use of dual modality probes. Upon clear definition of clinical utility, other important and practical issues related to business operational model, clinical workflow and reimbursement will also be resolved.

  2. Automatic quantitative analysis of cardiac MR perfusion images

    NASA Astrophysics Data System (ADS)

    Breeuwer, Marcel M.; Spreeuwers, Luuk J.; Quist, Marcel J.

    2001-07-01

    Magnetic Resonance Imaging (MRI) is a powerful technique for imaging cardiovascular diseases. The introduction of cardiovascular MRI into clinical practice is however hampered by the lack of efficient and accurate image analysis methods. This paper focuses on the evaluation of blood perfusion in the myocardium (the heart muscle) from MR images, using contrast-enhanced ECG-triggered MRI. We have developed an automatic quantitative analysis method, which works as follows. First, image registration is used to compensate for translation and rotation of the myocardium over time. Next, the boundaries of the myocardium are detected and for each position within the myocardium a time-intensity profile is constructed. The time interval during which the contrast agent passes for the first time through the left ventricle and the myocardium is detected and various parameters are measured from the time-intensity profiles in this interval. The measured parameters are visualized as color overlays on the original images. Analysis results are stored, so that they can later on be compared for different stress levels of the heart. The method is described in detail in this paper and preliminary validation results are presented.

  3. Early Support of Intracranial Perfusion

    DTIC Science & Technology

    2013-10-01

    automated real-time vital signs monitoring data” was funded by USAF (MSA); UM PI: Deborah Stein  The project, titled “Noninvasive intracranial pressure ...scoring of cerebral perfusion pressure and intracranial pressure provides a Brain Trauma Index that predicts outcome in patients with severe TBI... intracranial pressure dose index: Dynamic 3-D scoring in the assessment of Traumatic Brain Injury Proceedings of American Association for the Surgery of

  4. Neonatal aortic arch hemodynamics and perfusion during cardiopulmonary bypass.

    PubMed

    Pekkan, Kerem; Dur, Onur; Sundareswaran, Kartik; Kanter, Kirk; Fogel, Mark; Yoganathan, Ajit; Undar, Akif

    2008-12-01

    The objective of this study is to quantify the detailed three-dimensional (3D) pulsatile hemodynamics, mechanical loading, and perfusion characteristics of a patient-specific neonatal aortic arch during cardiopulmonary bypass (CPB). The 3D cardiac magnetic resonance imaging (MRI) reconstruction of a pediatric patient with a normal aortic arch is modified based on clinical literature to represent the neonatal morphology and flow conditions. The anatomical dimensions are verified from several literature sources. The CPB is created virtually in the computer by clamping the ascending aorta and inserting the computer-aided design model of the 10 Fr tapered generic cannula. Pulsatile (130 bpm) 3D blood flow velocities and pressures are computed using the commercial computational fluid dynamics (CFD) software. Second order accurate CFD settings are validated against particle image velocimetry experiments in an earlier study with a complex cardiovascular unsteady benchmark. CFD results in this manuscript are further compared with the in vivo physiological CPB pressure waveforms and demonstrated excellent agreement. Cannula inlet flow waveforms are measured from in vivo PC-MRI and 3 kg piglet neonatal animal model physiological experiments, distributed equally between the head-neck vessels and the descending aorta. Neonatal 3D aortic hemodynamics is also compared with that of the pediatric and fetal aortic stages. Detailed 3D flow fields, blood damage, wall shear stress (WSS), pressure drop, perfusion, and hemodynamic parameters describing the pulsatile energetics are calculated for both the physiological neonatal aorta and for the CPB aorta assembly. The primary flow structure is the high-speed canulla jet flow (approximately 3.0 m/s at peak flow), which eventually stagnates at the anterior aortic arch wall and low velocity flow in the cross-clamp pouch. These structures contributed to the reduced flow pulsatility (85%), increased WSS (50%), power loss (28%), and blood

  5. 12-tetradecanoyl-phorbol-13-acetate (PMA) produces injury to isolated rat lungs in the presence and absence of perfused neutrophils

    SciTech Connect

    Carpenter, L.J.; Roth, R.A.

    1986-03-01

    PMA produced injury to isolated, perfused rat lungs when eutrophils were added to or omitted from the buffer/albumin perfusion medium. When a high dose of PMA (57 ng/ml) was added to medium devoid of added neutrophils, perfusion pressure and lung weight increased. Together, superoxide dismutase (500 U/ml) and catalase (400 U/ml) had no effect on the increases in lung weight or perfusion pressure. However, papaverine (0.5 mM) prevented both the increase in perfusion pressure and fluid accumulation. When a concentration of PMA (14 ng/ml) that did not by itself cause lungs to accumulate fluid was added to perfusion medium containing neutrophils (1 x 10/sup 8/), perfusion pressures increased and lungs accumulated fluid. This concentration of PMA stimulated neutrophils (1 x 10/sup 8/) to release superoxide. Addition of superoxide dismutase (500 U/ml) and catalase (400 U/ml) to this medium prevented the increase in lung weight, but not the increase in perfusion pressure. Papaverine (0.5 mM) attenuated the increase in perfusion pressure and prevented fluid accumulation in these lungs. In summary, high concentrations of PMA produce lung injury which is independent of oxygen radicals; at lower concentrations it produces injury which is neutrophil-dependent and mediated by oxygen radicals.

  6. Intestinal perfusion monitoring using photoplethysmography

    NASA Astrophysics Data System (ADS)

    Akl, Tony J.; Wilson, Mark A.; Ericson, M. Nance; Coté, Gerard L.

    2013-08-01

    In abdominal trauma patients, monitoring intestinal perfusion and oxygen consumption is essential during the resuscitation period. Photoplethysmography is an optical technique potentially capable of monitoring these changes in real time to provide the medical staff with a timely and quantitative measure of the adequacy of resuscitation. The challenges for using optical techniques in monitoring hemodynamics in intestinal tissue are discussed, and the solutions to these challenges are presented using a combination of Monte Carlo modeling and theoretical analysis of light propagation in tissue. In particular, it is shown that by using visible wavelengths (i.e., 470 and 525 nm), the perfusion signal is enhanced and the background contribution is decreased compared with using traditional near-infrared wavelengths leading to an order of magnitude enhancement in the signal-to-background ratio. It was further shown that, using the visible wavelengths, similar sensitivity to oxygenation changes could be obtained (over 50% compared with that of near-infrared wavelengths). This is mainly due to the increased contrast between tissue and blood in that spectral region and the confinement of the photons to the thickness of the small intestine. Moreover, the modeling results show that the source to detector separation should be limited to roughly 6 mm while using traditional near-infrared light, with a few centimeters source to detector separation leads to poor signal-to-background ratio. Finally, a visible wavelength system is tested in an in vivo porcine study, and the possibility of monitoring intestinal perfusion changes is showed.

  7. Advanced Techniques in Musculoskeletal Oncology: Perfusion, Diffusion, and Spectroscopy.

    PubMed

    Teixeira, Pedro A Gondim; Beaumont, Marine; Gabriela, Hossu; Bailiang, Chen; Verhaeghe, Jean-luc; Sirveaux, François; Blum, Alain

    2015-12-01

    The imaging characterization of musculoskeletal tumors can be challenging, and a significant number of lesions remain indeterminate when conventional imaging protocols are used. In recent years, clinical availability of functional imaging methods has increased. Functional imaging has the potential to improve tumor detection, characterization, and follow-up. The most frequently used functional methods are perfusion imaging, diffusion-weighted imaging (DWI), and MR proton spectroscopy (MRS). Each of these techniques has specific protocol requirements and diagnostic pitfalls that need to be acknowledged to avoid misdiagnoses. Additionally, the application of functional methods in the MSK system has various technical issues that need to be addressed to ensure data quality and comparability. In this article, the application of contrast-enhanced perfusion imaging, DWI, and MRS for the evaluation of bone and soft tissue tumors is discussed, with emphasis on acquisition protocols, technical difficulties, and current clinical indications.

  8. Comparison Between Perfusion Computed Tomography and Dynamic Contrast-Enhanced Magnetic Resonance Imaging in Rectal Cancer

    SciTech Connect

    Kierkels, Roel G.J.; Backes, Walter H.; Janssen, Marco H.M.; Buijsen, Jeroen; Beets-Tan, Regina G.H.; Lambin, Philippe; Lammering, Guido; Oellers, Michel C.; Aerts, Hugo J.W.L.

    2010-06-01

    Purpose: To compare pretreatment scans with perfusion computed tomography (pCT) vs. dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in rectal tumors. Methods and Materials: Nineteen patients diagnosed with rectal cancer were included in this prospective study. All patients underwent both pCT and DCE-MRI. Imaging was performed on a dedicated 40-slice CT-positron emission tomography system and a 3-T MRI system. Dynamic contrast enhancement was measured in tumor tissue and the external iliac artery. Tumor perfusion was quantified in terms of pharmacokinetic parameters: transfer constant K{sup trans}, fractional extravascular-extracellular space v{sub e}, and fractional plasma volume v{sub p}. Pharmacokinetic parameter values and their heterogeneity (by 80% quantile value) were compared between pCT and DCE-MRI. Results: Tumor K{sup trans} values correlated significantly for the voxel-by-voxel-derived median (Kendall's tau correlation, tau = 0.81, p < 0.001) and 80% quantile (tau = 0.54, p = 0.04), as well as for the averaged uptake (tau = 0.58, p = 0.03). However, no significant correlations were found for v{sub e} and v{sub p} derived from the voxel-by-voxel-derived median and 80% quantile and derived from the averaged uptake curves. Conclusions: This study demonstrated for the first time that pCT provides K{sup trans} values comparable to those of DCE-MRI. However, no correlation was found for the v{sub e} and v{sub p} parameters between CT and MRI. Computed tomography can serve as an alternative modality to MRI for the in vivo evaluation of tumor angiogenesis in terms of the transfer constant K{sup trans}.

  9. TU-CD-BRB-12: Radiogenomics of MRI-Guided Prostate Cancer Biopsy Habitats

    SciTech Connect

    Stoyanova, R; Lynne, C; Abraham, S; Patel, M; Jorda, M; Kryvenko, O; Ishkanian, A; Abramowitz, M; Pollack, A; Tachar, M; Erho, N; Buerki, C; Lam, L; Davicioni, E

    2015-06-15

    Purpose: Diagnostic prostate biopsies are subject to sampling bias. We hypothesize that quantitative imaging with multiparametric (MP)-MRI can more accurately direct targeted biopsies to index lesions associated with highest risk clinical and genomic features. Methods: Regionally distinct prostate habitats were delineated on MP-MRI (T2-weighted, perfusion and diffusion imaging). Directed biopsies were performed on 17 habitats from 6 patients using MRI-ultrasound fusion. Biopsy location was characterized with 52 radiographic features. Transcriptome-wide analysis of 1.4 million RNA probes was performed on RNA from each habitat. Genomics features with insignificant expression values (<0.25) and interquartile range <0.5 were filtered, leaving total of 212 genes. Correlation between imaging features, genes and a 22 feature genomic classifier (GC), developed as a prognostic assay for metastasis after radical prostatectomy was investigated. Results: High quality genomic data was derived from 17 (100%) biopsies. Using the 212 ‘unbiased’ genes, the samples clustered by patient origin in unsupervised analysis. When only prostate cancer related genomic features were used, hierarchical clustering revealed samples clustered by needle-biopsy Gleason score (GS). Similarly, principal component analysis of the imaging features, found the primary source of variance segregated the samples into high (≥7) and low (6) GS. Pearson’s correlation analysis of genes with significant expression showed two main patterns of gene expression clustering prostate peripheral and transitional zone MRI features. Two-way hierarchical clustering of GC with radiomics features resulted in the expected groupings of high and low expressed genes in this metastasis signature. Conclusions: MP-MRI-targeted diagnostic biopsies can potentially improve risk stratification by directing pathological and genomic analysis to clinically significant index lesions. As determinant lesions are more reliably

  10. Diffusion MRI

    NASA Astrophysics Data System (ADS)

    Fukuyama, Hidenao

    Recent advances of magnetic resonance imaging have been described, especially stressed on the diffusion sequences. We have recently applied the diffusion sequence to functional brain imaging, and found the appropriate results. In addition to the neurosciences fields, diffusion weighted images have improved the accuracies of clinical diagnosis depending upon magnetic resonance images in stroke as well as inflammations.

  11. MRI visualisation by digitally reconstructed radiographs

    NASA Astrophysics Data System (ADS)

    Serrurier, Antoine; Bönsch, Andrea; Lau, Robert; Deserno, Thomas M.

    2015-03-01

    Visualising volumetric medical images such as computed tomography and magnetic resonance imaging (MRI) on picture archiving and communication systems (PACS) clients is often achieved by image browsing in sagittal, coronal or axial views or three-dimensional (3D) rendering. This latter technique requires fine thresholding for MRI. On the other hand, computing virtual radiograph images, also referred to as digitally reconstructed radiographs (DRR), provides in a single two-dimensional (2D) image a complete overview of the 3D data. It appears therefore as a powerful alternative for MRI visualisation and preview in PACS. This study describes a method to compute DRR from T1-weighted MRI. After segmentation of the background, a histogram distribution analysis is performed and each foreground MRI voxel is labeled as one of three tissues: cortical bone, also known as principal absorber of the X-rays, muscle and fat. An intensity level is attributed to each voxel according to the Hounsfield scale, linearly related to the X-ray attenuation coefficient. Each DRR pixel is computed as the accumulation of the new intensities of the MRI dataset along the corresponding X-ray. The method has been tested on 16 T1-weighted MRI sets. Anterior-posterior and lateral DRR have been computed with reasonable qualities and avoiding any manual tissue segmentations. This proof-of-concept holds for research application for use in clinical PACS.

  12. Ultrasound perfusion signal processing for tumor detection

    NASA Astrophysics Data System (ADS)

    Kim, MinWoo; Abbey, Craig K.; Insana, Michael F.

    2016-04-01

    Enhanced blood perfusion in a tissue mass is an indication of neo-vascularity and a sign of a potential malignancy. Ultrasonic pulsed-Doppler imaging is a preferred modality for noninvasive monitoring of blood flow. However, the weak blood echoes and disorganized slow flow make it difficult to detect perfusion using standard methods without the expense and risk of contrast enhancement. Our research measures the efficiency of conventional power-Doppler (PD) methods at discriminating flow states by comparing measurement performance to that of an ideal discriminator. ROC analysis applied to the experimental results shows that power Doppler methods are just 30-50 % efficient at perfusion flows less than 1ml/min, suggesting an opportunity to improve perfusion assessment through signal processing. A new perfusion estimator is proposed by extending the statistical discriminator approach. We show that 2-D perfusion color imaging may be enhanced using this approach.

  13. Emerging MRI methods in rheumatoid arthritis.

    PubMed

    Borrero, Camilo G; Mountz, James M; Mountz, John D

    2011-02-01

    New MRI techniques have been developed to assess not only the static anatomy of synovial hyperplasia, bone changes and cartilage degradation in patients with rheumatoid arthritis (RA), but also the activity of the physiological events that cause these changes. This enables an estimation of the rate of change in the synovium, bone and cartilage as a result of disease activity or in response to therapy. Typical MRI signs of RA in the pre-erosive phase include synovitis, bone marrow edema and subchondral cyst formation. Synovitis can be assessed by T2-weighted imaging, dynamic contrast-enhanced MRI or diffusion tensor imaging. Bone marrow edema can be detected on fluid-sensitive sequences such as short-tau inversion recovery or T2-weighted fast-spin echo sequences. Detection of small bone erosions in the early erosive phase using T1-weighted MRI has sensitivity comparable to CT. Numerous MRI techniques have been developed for quantitative assessment of potentially pathologic changes in cartilage composition that occur before frank morphologic changes. In this Review, we summarize the advances and new directions in the field of MRI, with an emphasis on their current state of development and application in RA.

  14. New insights on COPD imaging via CT and MRI

    PubMed Central

    Sverzellati, N; Molinari, F; Pirronti, T; Bonomo, L; Spagnolo, P; Zompatori, M

    2007-01-01

    Multidetector-row computed tomography (MDCT) can be used to quantify morphological features and investigate structure/function relationship in COPD. This approach allows a phenotypical definition of COPD patients, and might improve our understanding of disease pathogenesis and suggest new therapeutical options. In recent years, magnetic resonance imaging (MRI) has also become potentially suitable for the assessment of ventilation, perfusion and respiratory mechanics. This review focuses on the established clinical applications of CT, and novel CT and MRI techniques, which may prove valuable in evaluating the structural and functional damage in COPD. PMID:18229568

  15. Insulin resistance is associated with lower arterial blood flow and reduced cortical perfusion in cognitively asymptomatic middle-aged adults.

    PubMed

    Hoscheidt, Siobhan M; Kellawan, J Mikhail; Berman, Sara E; Rivera-Rivera, Leonardo A; Krause, Rachel A; Oh, Jennifer M; Beeri, Michal S; Rowley, Howard A; Wieben, Oliver; Carlsson, Cynthia M; Asthana, Sanjay; Johnson, Sterling C; Schrage, William G; Bendlin, Barbara B

    2016-01-01

    Insulin resistance (IR) is associated with poor cerebrovascular health and increased risk for dementia. Little is known about the unique effect of IR on both micro- and macrovascular flow particularly in midlife when interventions against dementia may be most effective. We examined the effect of IR as indexed by the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) on cerebral blood flow in macro- and microvessels utilizing magnetic resonance imaging (MRI) among cognitively asymptomatic middle-aged individuals. We hypothesized that higher HOMA-IR would be associated with reduced flow in macrovessels and lower cortical perfusion. One hundred and twenty cognitively asymptomatic middle-aged adults (57 ± 5 yrs) underwent fasting blood draw, phase contrast-vastly undersampled isotropic projection reconstruction (PC VIPR) MRI, and arterial spin labeling (ASL) perfusion. Higher HOMA-IR was associated with lower arterial blood flow, particularly within the internal carotid arteries (ICAs), and lower cerebral perfusion in several brain regions including frontal and temporal lobe regions. Higher blood flow in bilateral ICAs predicted greater cortical perfusion in individuals with lower HOMA-IR, a relationship not observed among those with higher HOMA-IR. Findings provide novel evidence for an uncoupling of macrovascular blood flow and microvascular perfusion among individuals with higher IR in midlife.

  16. Continuous plant cell perfusion culture: bioreactor characterization and secreted enzyme production.

    PubMed

    Su, Wei Wen; Arias, Renee

    2003-01-01

    Culture perfusion is widely practiced in mammalian cell processes to enhance secreted antibody production. Here, we report the development of an efficient continuous perfusion process for the cultivation of plant cell suspensions. The key to this process is a perfusion bioreactor that incorporates an annular settling zone into a stirred-tank bioreactor to achieve continuous cell/medium separation via gravitational sedimentation. From washout experiments, we found that under typical operating conditions (e.g., 200 rpm and 0.3 vvm) the liquid phase in the entire perfusion bioreactor was homogeneous despite the presence of the cylindrical baffle. Using secreted acid phosphatase (APase) produced in Anchusa officinalis cell culture as a model we have studied the perfusion cultures under complete or partial cell retention. The perfusion culture was operated under phosphate limitation to stimulate APase production. Successful operation of the perfusion process over four weeks has been achieved in this work. When A. officinalis cells were grown in the perfusion reactor and perfused at up to 0.4 vvd with complete cell retention, a cell dry weight exceeding 20 g/l could be achieved while secreted APase productivity leveled off at approximately 300 units/l/d. The culture became extremely dense with the maximum packed cell volume (PCV) surpassing 70%. In comparison, the maximum cell dry weight and overall secreted APase productivity in a typical batch culture were 10-12 g/l and 100-150 units/l/d, respectively. Operation of the perfusion culture under extremely high PCV for a prolonged period, however, led to declined oxygen uptake and reduced viability. Subsequently, cell removal via a bleed stream at up to 0.11 vvd was tested and shown to stabilize the culture at a PCV below 60%. With culture bleeding, both specific oxygen uptake rate and viability were shown to increase. This also led to a higher cell dry weight exceeding 25 g/l, and further improvement of secreted APase

  17. Value of intravoxel incoherent motion and dynamic contrast-enhanced MRI for predicting the early and short-term responses to chemoradiotherapy in nasopharyngeal carcinoma

    PubMed Central

    Hou, Jing; Yu, Xiaoping; Hu, Yin; Li, Feiping; Xiang, Wang; Wang, Lanlan; Wang, Hui; Lu, Qiang; Zhang, Zhongping; Zeng, Wenbin

    2016-01-01

    Abstract The aim of the study was to investigate the value of intravoxel incoherent motion diffusion-weighted magnetic resonance imaging (IVIM-DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in predicting the early and short-term responses to chemoradiotherapy (CRT) in patients with nasopharyngeal carcinoma (NPC). Forty-three NPC patients underwent IVIM-DWI and DCE-MRI at baseline (pretreatment) and after the first cycle of induction chemotherapy (posttreatment). Based on whether locoregional lesions were identified, patients were divided into the residual and nonresidual groups at the end of CRT and into the good-responder and poor-responder groups 6 months after the end of CRT. The pretreatment and posttreatment IVIM-DWI parameters (ADC, D, D∗, and f) and DCE-MRI parameters (Ktrans, Kep, and Ve) values and their percentage changes (Δ%) were compared between the residual and nonresidual groups and between the good-responder and poor-responder groups. None of perfusion-related parametric values derived from either DCE-MRI or IVIM-DWI showed significant differences either between the residual and nonresidual groups or between the good-responder and poor-responder groups. The nonresidual group exhibited lower pre-ADC, lower pre-D, and higher Δ%D values than did the residual group (all P <0.05). The good-responder group had lower pre-D and pre-ADC values than did the poor-responder group (both P <0.05). Based on receiver operating characteristic (ROC) curve analysis, pre-D had the highest area under the curve in predicting both the early and short-term responses to CRT for NPC patients (0.817 and 0.854, respectively). IVIM-DWI is more valuable than DCE-MRI in predicting the early and short-term response to CRT for NPC, and furthermore diffusion-related IVIM-DWI parameters (pre-ADC, pre-D, and Δ%D) are more powerful than perfusion-related parameters derived from both IVIM-DWI and DCE-MRI. PMID:27583847

  18. Perfusion-diffusion mismatch: does it identify who will benefit from reperfusion therapy?

    PubMed

    Powers, William J

    2012-06-01

    A method to determine which patients would benefit from reperfusion therapies after 4.5 h would greatly add to our ability to reduce the disability caused by stroke. The goal of magnetic resonance perfusion-diffusion imaging in hyperacute ischemic stroke is to identify regions of the brain that will die if untreated and will live and regain function if quickly reperfused. The clinical value of perfusion-diffusion imaging in hyperacute ischemic stroke can be proven only by demonstrating empirically in a randomized controlled trial (RCT) that there is an improvement in patient outcome that depends on the use of the neuroimaging modality to guide therapy. To date, there have been only a few RCTs that have evaluated whether perfusion-diffusion imaging can identify a subgroup of patients with ischemic stroke more than 4.5 h from onset in whom the overall benefit from reperfusion therapy outweighs the risk. None have met the rigorous design requirements of the three-group study necessary to adequately test this hypothesis, and none have even met their own criteria for demonstrating a clinical benefit. While studies are not sufficient to conclusively disprove the hypothesis there are no RCT data to support it, and thus, the clinical value of MRI perfusion-diffusion imaging in this setting remains unproven. It is worthy of further investigation in rigorously designed RCTs. However, the risks of symptomatic intracerebral hemorrhage with reperfusion therapies in acute ischemic stroke are proven. Unless RCT data are forthcoming to demonstrate that MRI perfusion-diffusion mismatch improves clinical outcome, it should not be used to guide delayed reperfusion therapy.

  19. Efficient method for calculating kinetic parameters using T1-weighted dynamic contrast-enhanced magnetic resonance imaging.

    PubMed

    Murase, Kenya

    2004-04-01

    It has become increasingly important to quantitatively estimate tissue physiological parameters such as perfusion, capillary permeability, and the volume of extravascular-extracellular space (EES) using T(1)-weighted dynamic contrast-enhanced MRI (DCE-MRI). A linear equation was derived by integrating the differential equation describing the kinetic behavior of contrast agent (CA) in tissue, from which K(1) (rate constant for the transfer of CA from plasma to EES), k(2) (rate constant for the transfer from EES to plasma), and V(p) (plasma volume) can be easily obtained by the linear least-squares (LLSQ) method. The usefulness of this method was investigated by means of computer simulations, in comparison with the nonlinear least-squares (NLSQ) method. The new method calculated the above parameters faster than the NLSQ method by a factor of approximately 6, and estimated them more accurately than the NLSQ method at a signal-to-noise ratio (SNR) of < approximately 10. This method will be useful for generating functional images of K(1), k(2), and V(p) from DCE-MRI data.

  20. Simplified quantification of labile proton concentration-weighted chemical exchange rate (k(ws) ) with RF saturation time dependent ratiometric analysis (QUESTRA): normalization of relaxation and RF irradiation spillover effects for improved quantitative chemical exchange saturation transfer (CEST) MRI.

    PubMed

    Sun, Phillip Zhe

    2012-04-01

    Chemical exchange saturation transfer MRI is an emerging imaging technique capable of detecting dilute proteins/peptides and microenvironmental properties, with promising in vivo applications. However, chemical exchange saturation transfer MRI contrast is complex, varying not only with the labile proton concentration and exchange rate, but also with experimental conditions such as field strength and radiofrequency (RF) irradiation scheme. Furthermore, the optimal RF irradiation power depends on the exchange rate, which must be estimated in order to optimize the chemical exchange saturation transfer MRI experiments. Although methods including numerical fitting with modified Bloch-McConnell equations, quantification of exchange rate with RF saturation time and power (QUEST and QUESP), have been proposed to address this relationship, they require multiple-parameter non-linear fitting and accurate relaxation measurement. Our work extended the QUEST algorithm with ratiometric analysis (QUESTRA) that normalizes the magnetization transfer ratio at labile and reference frequencies, which effectively eliminates the confounding relaxation and RF spillover effects. Specifically, the QUESTRA contrast approaches its steady state mono-exponentially at a rate determined by the reverse exchange rate (k(ws) ), with little dependence on bulk water T(1) , T(2) , RF power and chemical shift. The proposed algorithm was confirmed numerically, and validated experimentally using a tissue-like phantom of serially titrated pH compartments.

  1. A Novel MRI Marker for Prostate Brachytherapy

    SciTech Connect

    Frank, Steven J. Stafford, R. Jason; Bankson, James A.; Li Chun; Swanson, David A.; Kudchadker, Rajat J.; Martirosyan, Karen S.

    2008-05-01

    Purpose: Magnetic resonance imaging (MRI) is the optimal imaging modality for the prostate and surrounding critical organ structures. However, on MRI, the titanium radioactive seeds used for brachytherapy appear as black holes (negative contrast) and cannot be accurately localized. We sought to develop an encapsulated contrast agent marker (ECAM) with high-signal intensity on MRI to permit accurate localization of radioactive seeds with MRI during and after prostate brachytherapy. Methods and Materials: We investigated several agents with paramagnetic and superparamagnetic properties. The agents were injected into titanium, acrylic, and glass seeds, which were linked together in various combinations and imaged with MRI. The agent with the greatest T1-weighted signal was tested further in a canine prostate and agarose phantom. Studies were performed on a 1.5-T clinical MRI scanner. Results: The cobalt-chloride complex contrast (C4) agent with stoichiometry (CoCl{sub 2}){sub 0.8}(C{sub 2}H{sub 5}NO{sub 2}){sub 0.2} had the greatest T1-weighted signal (positive contrast) with a relaxivity ratio >1 (r{sub 2}/r{sub 1} = 1.21 {+-} 0.29). Acrylic-titanium and glass-titanium seed strands were clearly visualized with the encapsulated contrast agent marker. Conclusion: We have developed a novel ECAM that permits positive identification of the radioactive seeds used for prostate brachytherapy on MRI. Preclinical in vitro phantom studies and in vivo canine studies are needed to further optimize MRI sequencing techniques to facilitate MRI-based dosimetry.

  2. Synthetic quantitative MRI through relaxometry modelling

    PubMed Central

    Mohammadi, Siawoosh; Weiskopf, Nikolaus

    2016-01-01

    Abstract Quantitative MRI (qMRI) provides standardized measures of specific physical parameters that are sensitive to the underlying tissue microstructure and are a first step towards achieving maps of biologically relevant metrics through in vivo histology using MRI. Recently proposed models have described the interdependence of qMRI parameters. Combining such models with the concept of image synthesis points towards a novel approach to synthetic qMRI, in which maps of fundamentally different physical properties are constructed through the use of biophysical models. In this study, the utility of synthetic qMRI is investigated within the context of a recently proposed linear relaxometry model. Two neuroimaging applications are considered. In the first, artefact‐free quantitative maps are synthesized from motion‐corrupted data by exploiting the over‐determined nature of the relaxometry model and the fact that the artefact is inconsistent across the data. In the second application, a map of magnetization transfer (MT) saturation is synthesized without the need to acquire an MT‐weighted volume, which directly leads to a reduction in the specific absorption rate of the acquisition. This feature would be particularly important for ultra‐high field applications. The synthetic MT map is shown to provide improved segmentation of deep grey matter structures, relative to segmentation using T 1‐weighted images or R 1 maps. The proposed approach of synthetic qMRI shows promise for maximizing the extraction of high quality information related to tissue microstructure from qMRI protocols and furthering our understanding of the interrelation of these qMRI parameters. PMID:27753154

  3. INTRAVENOUS REGIONAL ANTIBIOTIC PERFUSION THERAPY AS AN ADJUNCTIVE TREATMENT FOR DIGITAL LESIONS IN SEABIRDS.

    PubMed

    Fiorello, Christine V

    2017-03-01

    Foot infections are a common problem among seabirds in wildlife rehabilitation. Pododermatitis and digital infections are often challenging to treat because of the presence of suboptimal substrates, abnormal weight-bearing due to injuries, and suboptimal nutritional or health status. Seabirds represent the majority of animals requiring rehabilitation after oil spills, and foot problems are a common reason for euthanasia among these birds. Antibiotic intravenous regional perfusion therapy is frequently used in humans and other species to treat infections of the distal extremities, but it has not been evaluated in seabirds. During the 2015 Refugio oil spill response, four birds with foot lesions (pododermatitis, osteomyelitis, or both) were treated with ampicillin/sulbactam administered intravenously to the affected limb(s) in addition to systemic antibiotics and anti-inflammatories. Three of the birds, all brown pelicans ( Pelecanus occidentalis ) recovered rapidly and were released. Two of these birds had acute pododermatitis and were treated once with intravenous regional perfusion. They were released approximately 3 wk after the perfusion therapy. The third pelican had osteomyelitis of a digit. It was treated twice with intravenous regional perfusion and was released about 1 mo after the initial perfusion therapy. The fourth bird, a Pacific loon ( Gavia pacifica ), was treated once with perfusion therapy but did not respond to treatment and was euthanatized. No serious adverse effects were observed. This technique should be explored further in avian species.

  4. Perfusion Angiography of the Foot in Patients with Critical Limb Ischemia: Description of the Technique

    SciTech Connect

    Jens, Sjoerd Marquering, Henk A.; Koelemay, Mark J. W.; Reekers, Jim A.

    2015-02-15

    ObjectiveTo study the feasibility of 2D perfusion imaging in critical limb ischemia (CLI).Methods/ResultsPerfusion angiography is a new technology which was tested in 18 patients with CLI of the foot. A standardized protocol was used with a catheter placed at the mid-part of the popliteal artery, and a total of 9 cc of non-ionic iodinated contrast material was injected at a rate of 3 cc/sec. The technology is based on early cardiology research where iodinated contrast agents were used for imaging of cardiac perfusion. During the first pass of the contrast, there is a significant diffusion of the contrast agents into the interstitial space, particularly for non-ionic and low-molecular-weight compounds.DiscussionThe original angiography data can be used to make a time–density curve, which represents the actual perfusion of the foot in time. Angiographic perfusion imaging is a post-processing modality for which no extra contrast or radiation is needed. With this technique, it is possible to get more information about the perfusion status and microcirculation of the foot. This is a step toward functional imaging in CLI patients.

  5. PERFUSION FOR MYOCARDIAL REVASCULARIZATION WITHOUT AN ARTIFICIAL OXYGENATOR (New Method to Reduce Surgical Morbidity)

    PubMed Central

    De Moraes, Domingos Junqueira; Abilio, Fued Michel; Cunha, Marcos; Feitosa, Lionicio A.; Aragão, Esmeraldino; Cysne, Eumenes; Vieira, Roberto; Glavam, Haroldo C. C.; Zaniolo, Waldomiro; Netto, Mario Salles; Villela, Ronaldo De A.; Labrunie, Pierre

    1979-01-01

    Thirteen patients were submitted to direct myocardial revascularization (saphenous vein graft) without the use of an artificial oxygenator. The perfusion was done by a left ventricle-to-aorta bypass and autogenous oxygenation. Most patients had three grafts implanted plus endarterectomy of the distal right coronary artery. There was one hospital death that was apparently not related to the method used. Perfusion time ranged from 45 minutes to 4 hours. Body temperature during perfusion was kept between 25 and 30° C. Perfusion flow was maintained between 25 to 50 ml per kg of body weight per minute. Ischemic, hypothermic cardiac arrest was employed. We demonstrated for the first time that perfusion for this kind of heart surgery could be done with no artificial oxygenators and, apparently, is safer for the patients. There were no bleeding problems even in perfusions as long as 4 hours. There was no respiratory dysfunction, and artificial respiration was used for only 6 to 12 hours. The patients awoke at the end of surgery with no signs or symptoms of central nervous system damage, and vasopressor drugs were rarely used after surgery. Although the experience is very small, it suggests that many postoperative problems, especially those related to bleeding and respiratory dysfunction may be reduced or eliminated by this new method. PMID:15216319

  6. Identification of cerebral perfusion using arterial spin labeling in patients with seizures in acute settings

    PubMed Central

    Yoo, Roh-Eul; Yoon, Byung-Woo; Lee, Sang Kun; Lee, Soon-Tae; Kang, Koung Mi; Choi, Seung Hong; Kim, Ji-hoon; Sohn, Chul-Ho; Park, Sun-Won; Han, Moon Hee

    2017-01-01

    This study aimed to explore the utility of arterial spin labeling perfusion-weighted imaging (ASL-PWI) in patients with suspected seizures in acute settings. A total of 164 patients who underwent ASL-PWI for suspected seizures in acute settings (with final diagnoses of seizure [n = 129], poststroke seizure [n = 18], and seizure mimickers [n = 17]), were included in this retrospective study. Perfusion abnormality was analyzed for: (1) pattern, (2) multifocality, and (3) atypical distribution against vascular territories. Perfusion abnormality was detected in 39% (50/129) of the seizure patients, most (94%, 47/50) being the hyperperfusion pattern. Of the patients with perfusion abnormality, multifocality or hemispheric involvement and atypical distribution against vascular territory were revealed in 46% (23/50) and 98% (49/50), respectively. In addition, seizures showed characteristic features including hyperperfusion (with or without non-territorial distribution) on ASL-PWI, thus differentiating them from poststroke seizures or seizure mimickers. In patients in whom seizure focus could be localized on both EEG and ASL-PWI, the concordance rate was 77%. The present study demonstrates that ASL-PWI can provide information regarding cerebral perfusion status in patients with seizures in acute settings and has the potential to be used as a non-invasive imaging tool to identify the cerebral perfusion in patients with seizures. PMID:28291816

  7. Usefulness of cardiac MRI in the prognosis and follow-up of ischemic heart disease.

    PubMed

    Hidalgo, A; Pons-Lladó, G

    2015-01-01

    Cardiac magnetic resonance imaging (MRI) is an important tool that makes it possible to evaluate patients with cardiovascular disease; in addition to infarction and alterations in myocardial perfusion, cardiac MRI is useful for evaluating other phenomena such as microvascular obstruction and ischemia. The main prognostic factors in cardiac MRI are ventricular dysfunction, necrosis in late enhancement sequences, and ischemia in stress sequences. In acute myocardial infarction, cardiac MRI can evaluate the peri-infarct zone and quantify the size of the infarct. Furthermore, cardiac MRI's ability to detect and evaluate microvascular obstruction makes it a fundamental tool for establishing the prognosis of ischemic heart disease. In patients with chronic ischemic heart disease, cardiac MRI can detect ischemia induced by pharmacological stress and can diagnose infarcts that can be missed on other techniques.

  8. Machine Perfusion Enhances Hepatocyte Isolation Yields From Ischemic Livers

    PubMed Central

    Izamis, Maria-Louisa; Perk, Sinem; Calhoun, Candice; Uygun, Korkut; Yarmush, Martin L.; Berthiaume, François

    2015-01-01

    Background High-quality human hepatocytes form the basis of drug safety and efficacy tests, cell-based therapies, and bridge-to-transplantation devices. Presently the only supply of cells derives from an inadequate pool of suboptimal disqualified donor livers. Here we evaluated whether machine perfusion could ameliorate ischemic injury that many of these livers experience prior to hepatocyte isolation. Methods Non-heparinized female Lewis rat livers were exposed to an hour of warm ischemia (34°C) and then perfused for 3 hours. Five different perfusion conditions that utilized the cell isolation apparatus were investigated, namely: (1) modified Williams Medium E and (2) Lifor, both with active oxygenation (95%O2/5%CO2), as well as (3) Lifor passively oxygenated with ambient air (21%O2/0.04%CO2), all at ambient temperatures (20±2°C). At hypothermic temperatures (5±1°C) and under passive oxygenation were (4) University of Wisconsin solution (UW) and (5) Vasosol. Negative and positive control groups comprised livers that had ischemia (WI) and livers that did not (Fresh) prior to cell isolation, respectively. Results Fresh livers yielded 32±9 million cells/g liver while an hour of ischemia reduced the cell yield to 1.6±0.6 million cells/g liver. Oxygenated Williams medium E and Lifor recovered yields of 39±11 and 31±2.3 million cells/g liver, respectively. The passively oxygenated groups produced 15±7 (Lifor), 13±7 (Vasosol), and 10±6 (UW) million cells/g liver. Oxygenated Williams Medium E was most effective at sustaining pH values, avoiding the accumulation of lactate, minimizing edematous weight gain and producing bile during perfusion. Conclusions Machine perfusion results in a dramatic increase in cell yields from livers that have had up to an hour of warm ischemia, but perfusate choice significantly impacts the extent of recovery. Oxygenated Williams Medium E at room temperature is superior to Lifor, UW and Vasosol, largely facilitated by its high

  9. MR mapping of temperature and perfusion for hyperthermia therapy

    NASA Astrophysics Data System (ADS)

    Wlodarczyk, Waldemar; Vlad, Julia; Lange, Thomas; Wust, Peter; Felix, Roland

    2001-05-01

    The promising results, recently obtained in phantom experiments employing the MR-based proton resonance frequency (PRF) method as a non-invasive tool for the temperature monitoring of hyperthermia therapy, are not easily reproduced in vivo. One of the reasons is the impact of perfusion changes on the PRF-measured temperature. In our experiments in vivo, heat was supplied on one side of the volunteers knee or pelvis by a rubber hose with circulating warm water (50iC). The PRF method was calibrated by the constant temperature sensitivity of pure water of 0.011 ppm/iC. MR mapping of perfusion changes was based on T2*-weighted tracking of the first-pass kinetics of contrast agent. The hemodynamic parameters of regional blood volume (rBV) and mean transit time (MTT) were extracted by fitting pixel-by-pixel the first- pass kinetics to the gamma-variate model. Special attention was directed to improve a quality of the automatic non-linear fit at low signal-to-noise values. The distributions of PRF- based temperature changes show large areas of apparently high temperature elevations (exceeding 10iC) in regions close to the heat source, and others with just as large temperature decays in more distant regions. Areas of apparently high temperature elevations correlate with areas of blood flow increase and vice versa. In conclusion, the visible heat- induced PRF changes in vivo are primarily perfusion changes, which mask the much smaller true temperature changes.

  10. Near-Infrared Spectroscopy versus Magnetic Resonance Imaging To Study Brain Perfusion in Newborns with Hypoxic-Ischemic Encephalopathy Treated with Hypothermia

    PubMed Central

    Wintermark, P.; Hansen, A.; Warfield, SK.; Dukhovny, D.; Soul, JS.

    2014-01-01

    Background The measurement of brain perfusion may provide valuable information for assessment and treatment of newborns with hypoxic-ischemic encephalopathy (HIE). While arterial spin labeled perfusion (ASL) magnetic resonance imaging (MRI) provides noninvasive and direct measurements of regional cerebral blood flow (CBF) values, it is logistically challenging to obtain. Near-infrared spectroscopy (NIRS) might be an alternative, as it permits noninvasive and continuous monitoring of cerebral hemodynamics and oxygenation at the bedside. Objective The purpose of this study is to determine the correlation between measurements of brain perfusion by NIRS and by MRI in term newborns with HIE treated with hypothermia. Design/Methods In this prospective cohort study, ASL-MRI and NIRS performed during hypothermia were used to assess brain perfusion in these newborns. Regional cerebral blood flow values (CBF), measured from 1–2 MRI scans for each patient, were compared to mixed venous saturation values (SctO2) recorded by NIRS just before and after each MRI. Analysis included groupings into moderate versus severe HIE based on their initial background pattern of amplitude-integrated electroencephalogram. Results Twelve concomitant recordings were obtained of seven neonates. Strong correlation was found between SctO2 and CBF in asphyxiated newborns with severe HIE (r = 0.88; p value = 0.0085). Moreover, newborns with severe HIE had lower CBF (likely lower oxygen supply) and extracted less oxygen (likely lower oxygen demand or utilization) when comparing SctO2 and CBF to those with moderate HIE. Conclusions NIRS is an effective bedside tool to monitor and understand brain perfusion changes in term asphyxiated newborns, which in conjunction with precise measurements of CBF obtained by MRI at particular times, may help tailor neuroprotective strategies in term newborns with HIE. PMID:23631990

  11. Cysticercosis of the masseter: MRI and sonographic correlation

    PubMed Central

    Nagarjuna, M; Belaval, V; Shetty, S; Salins, P C

    2015-01-01

    Cysticercal involvement of the masseter is an uncommon manifestation of a relatively common parasitic infestation. Sonographic evaluation of many isolated cases of cysticercosis has been extensively described. However, there are scanty reports on MRI appearance of cysticercal involvement of the masseter. This report presents classical imaging appearance of cysticercal involvement of the masseter on sonography and MRI. The pattern of the disease and MRI appearance of lesions in the masseter, highlighting the role of diffusion-weighted images, are described. PMID:25734242

  12. A brain stress test: Cerebral perfusion during memory encoding in mild cognitive impairment

    PubMed Central

    Xie, Long; Dolui, Sudipto; Das, Sandhitsu R.; Stockbower, Grace E.; Daffner, Molly; Rao, Hengyi; Yushkevich, Paul A.; Detre, John A.; Wolk, David A.

    2016-01-01

    Arterial spin labeled perfusion magnetic resonance imaging (ASL MRI) provides non-invasive quantification of cerebral blood flow, which can be used as a biomarker of brain function due to the tight coupling between cerebral blood flow (CBF) and brain metabolism. A growing body of literature suggests that regional CBF is altered in neurodegenerative diseases. Here we examined ASL MRI CBF in subjects with amnestic mild cognitive impairment (n = 65) and cognitively normal healthy controls (n = 62), both at rest and during performance of a memory-encoding task. As compared to rest, task-enhanced ASL MRI improved group discrimination, which supports the notion that physiologic measures during a cognitive challenge, or “stress test”, may increase the ability to detect subtle functional changes in early disease stages. Further, logistic regression analysis demonstrated that ASL MRI and concomitantly acquired structural MRI provide complementary information of disease status. The current findings support the potential utility of task-enhanced ASL MRI as a biomarker in early Alzheimer's disease. PMID:27222794

  13. Technetium myocardial perfusion agents: an introduction

    SciTech Connect

    English, R.J.; Kozlowski, J.; Tumeh, S.S.; Holman, B.L.

    1987-09-01

    This is the third in a series of four Continuing Education articles on developing radiopharmaceuticals. After reading this article, the reader should be able to: 1) understand the basic concepts of myocardial perfusion imaging; and 2) discuss the advantages of the technetium myocardial perfusion complexes over thallium-201.

  14. Luxury perfusion following anterior ischemic optic neuropathy.

    PubMed

    Friedland, S; Winterkorn, J M; Burde, R M

    1996-09-01

    We present five patients who developed luxury perfusion following anterior ischemic optic neuropathy in whom fluorescein angiography was misinterpreted as "capillary hemangioma" or neovascularization of the disc. In each case, the segment of disc hyperemia corresponded to a spared region of visual field. Luxury perfusion represents a reparative autoregulatory reaction to ischemia.

  15. Long term perfusion system supporting adipogenesis

    PubMed Central

    Abbott, Rosalyn D.; Raja, Waseem K.; Wang, Rebecca Y.; Stinson, Jordan A.; Glettig, Dean L.; Burke, Kelly A.; Kaplan, David L.

    2015-01-01

    Adipose tissue engineered models are needed to enhance our understanding of disease mechanisms and for soft tissue regenerative strategies. Perfusion systems generate more physiologically relevant and sustainable adipose tissue models, however adipocytes have unique properties that make culturing them in a perfusion environment challenging. In this paper we describe the methods involved in the development of two perfusion culture systems (2D and 3D) to test their applicability for long term in vitro adipogenic cultures. It was hypothesized that a silk protein biomaterial scaffold would provide a 3D framework, in combination with perfusion flow, to generate a more physiologically relevant sustainable adipose tissue engineered model than 2D cell culture. Consistent with other studies evaluating 2D and 3D culture systems for adipogenesis we found that both systems successfully model adipogensis, however 3D culture systems were more robust, providing the mechanical structure required to contain the large, fragile adipocytes that were lost in 2D perfused culture systems. 3D perfusion also stimulated greater lipogenesis and lipolysis and resulted in decreased secretion of LDH compared to 2D perfusion. Regardless of culture configuration (2D or 3D) greater glycerol was secreted with the increased nutritional supply provided by perfusion of fresh media. These results are promising for adipose tissue engineering applications including long term cultures for studying disease mechanisms and regenerative approaches, where both acute (days to weeks) and chronic (weeks to months) cultivation are critical for useful insight. PMID:25843606

  16. Myocardial perfusion with rubidium-82. III. Theory relating severity of coronary stenosis to perfusion deficit

    SciTech Connect

    Mullani, N.A.

    1984-11-01

    The relation between the quantitative perfusion deficit, as measured by emission computerized tomography, and the severity of coronary artery stenosis is important for the noninvasive clinical evaluation of coronary artery disease in man. Positron emission tomography allows direct noninvasive measurement of myocardial perfusion and quantification of the size of the perfusion defect. Given this important imformation, a mathematical model has been derived to gauge the severity of a coronary stenosis from quantitative perfusion measurements in the normal and poststenotic regions of the heart. The theoretical basis is presented for relating regional myocardial perfusion and regional perfusion resistance to total, coronary blood flow and resistance at normal resting flow and during maximal coronary vasodilation. The concept of perfusion reserve is presented as a clinical measure of the severity of a stenosis.

  17. High resolution 3D MRI of mouse mammary glands with intra-ductal injection of contrast media.

    PubMed

    Markiewicz, Erica; Fan, Xiaobing; Mustafi, Devkumar; Zamora, Marta; Roman, Brian B; Jansen, Sanaz A; Macleod, Kay; Conzen, Suzanne D; Karczmar, Gregory S

    2015-01-01

    The purpose of this study was to use high resolution three-dimensional (3D) magnetic resonance imaging (MRI) to study mouse mammary gland ductal architecture based on intra-ductal injection of contrast agents. Female FVB/N mice age 12-20 weeks (n=12), were used in this study. A 34G, 45° tip Hamilton needle with a 25μL Hamilton syringe was inserted into the tip of the nipple. Approximately 20-25μL of a Gadodiamide/Trypan blue/saline solution was injected slowly over one minute into the nipple and duct. To prevent washout of contrast media from ducts due to perfusion, and maximize the conspicuity of ducts on MRI, mice were sacrificed one minute after injection. High resolution 3D T1-weighted images were acquired on a 9.4T Bruker scanner after sacrifice to eliminate motion artifacts and reduce contrast media leakage from ducts. Trypan blue staining was well distributed throughout the ductal tree. MRI showed the mammary gland ductal structure clearly. In spoiled gradient echo T1-weighted images, the signal-to-noise ratio of regions identified as enhancing mammary ducts following contrast injection was significantly higher than that of muscle (p<0.02) and significantly higher than that of contralateral mammary ducts that were not injected with contrast media (p<0.0001). The methods described here could be adapted for injection of specialized contrast agents to measure metabolism or target receptors in normal ducts and ducts with in situ cancers.

  18. [Compromized myocardial perfusion in arrhythmias (author's transl)].

    PubMed

    Simon, H; Neumann, G; Felix, R; Hedde, H; Schaede, A; Thurn, P; Winkler, C

    1977-09-15

    In 7 patients with arrhythmias of various origin the myocardial scintigram displayed either a diffuse or circumscript defect of the perfusion. The coronary arteriogram was normal in all patients. The localized defect of the perfusion in 2 patients was in the region of the upper part of the interventricular septum. Both had a left bundle brunch block. A correlation between the perfusion defect and the electrophysiological abnormality seems probable. The perfusion defect in one of the patients is most probably caused by a previous myocarditis followed by fibrous changes. In the other 6 patients the cause for the perfusion defect is not obvious. A history of myocarditis is missing. The presence of "small vessel disease" in those patients has however to be considered. Our results point to the relation between an abnormality of the microcirculation and arrhythmias in younger patients.

  19. The PRESTO technique for fMRI

    PubMed Central

    van Gelderen, P.; Duyn, J.H.; Ramsey, N.F.; Liu, G.; Moonen, C.T.W.

    2012-01-01

    In the early days of BOLD fMRI, the acquisition of T2* weighted data was greatly facilitated by rapid scan techniques such as EPI. The latter, however, was only available on a few MRI systems that were equipped with specialized hardware that allowed rapid switching of the imaging gradients. For this reason, soon after the invention of fMRI, the scan technique PRESTO was developed to make rapid T2* weighted scanning available on standard clinical scanning. This method combined echo shifting, which allows for echo times longer than the sequence repetition time, with acquisition of multiple k-space lines per excitation. These two concepts were combined in order to achieve a method fast enough for fMRI, while maintaining a sufficiently long echo time for optimal contrast. PRESTO has been primarily used for 3D scanning, which minimized the contribution of large vessels due to inflow effects. Although PRESTO is still being used today, its appeal has lessened somewhat due to increased gradient performance of modern MRI scanners. Compared to 2D EPI, PRESTO may have somewhat reduced temporal stability, which is a disadvantage for fMRI that may not outweigh the advantage of reduced inflow effects provided by 3D scanning. In this overview, the history of the development of the PRESTO is presented, followed by a qualitative comparison with EPI. PMID:22245350

  20. Sinus MRI scan

    MedlinePlus

    ... sinuses. The test is noninvasive. MRI uses powerful magnets and radio waves instead of radiation. Signals from ... in the eyes. Because the MRI contains a magnet, metal-containing objects such as pens, pocketknives, and ...

  1. Arm MRI scan

    MedlinePlus

    ... arm MRI (magnetic resonance imaging) scan uses strong magnets to create pictures of the upper and lower ... in your eyes) Because the MRI contains strong magnets, metal objects are not allowed into the room ...

  2. MRI Safety during Pregnancy

    MedlinePlus

    ... 20 to 40 minutes. top of page Contrast material For some MRI exams, a contrast material called gadolinium will need to be injected into a vein in the arm. While contrast material sometimes improves the MRI images, during pregnancy the ...

  3. Weight Management

    MedlinePlus

    ... Weight share What It Takes to Lose Weight: Calorie Basics When you’re trying to lose weight... ... wcdapps.hhs.gov/Badges/Handlers/Badge.ashx?js=0&widgetname=betobaccofreew200short</NOFRAMES& ...

  4. First in vivo magnetic particle imaging of lung perfusion in rats.

    PubMed

    Zhou, Xinyi Yedda; Jeffris, Kenneth; Yu, Elaine; Zheng, Bo; Goodwill, Patrick; Nahid, Payam; Conolly, Steven

    2017-02-20

    Pulmonary embolism (PE), along with the closely related condition of deep vein thrombosis, affect an estimated 600,000 patients in the US per year. Untreated, PE carries a mortality rate of 30%. Because many patients experience mild or non-specific symptoms, imaging studies are necessary for definitive diagnosis of PE. Iodinated CT pulmonary angiography (CTPA) is recommended for most patients, while nuclear medicine-based ventilation/perfusion (V/Q) scans are reserved for patients in whom the use of iodine is contraindicated. Magnetic particle imaging (MPI) is an emerging tracer imaging modality with high image contrast (no tissue background signal) and sensitivity (200 nM Fe) to superparamagnetic iron oxide (SPIO) tracer. Importantly, unlike CT or nuclear medicine, MPI uses no ionizing radiation. Further, MPI is not derived from magnetic resonance imaging (MRI); MPI directly images SPIO tracers via their strong electronic magnetization, enabling deep imaging of anatomy including within the lungs, which is very challenging with MRI. Here, the first high-contrast in vivo MPI lung perfusion images of rats are shown using a novel lung perfusion agent, MAA-SPIOs.

  5. Reduction in cerebral perfusion after heroin administration: a resting state arterial spin labeling study.

    PubMed

    Denier, Niklaus; Gerber, Hana; Vogel, Marc; Klarhöfer, Markus; Riecher-Rossler, Anita; Wiesbeck, Gerhard A; Lang, Undine E; Borgwardt, Stefan; Walter, Marc

    2013-01-01

    Heroin dependence is a chronic relapsing brain disorder, characterized by the compulsion to seek and use heroin. Heroin itself has a strong potential to produce subjective experiences characterized by intense euphoria, relaxation and release from craving. The neurofunctional foundations of these perceived effects are not well known. In this study, we have used pharmacological magnetic resonance imaging (phMRI) in 15 heroin-dependent patients from a stable heroin-assisted treatment program to observe the steady state effects of heroin (60 min after administration). Patients were scanned in a cross-over and placebo controlled design. They received an injection of their regular dose of heroin or saline (placebo) before or after the scan. As phMRI method, we used a pulsed arterial spin labeling (ASL) sequence based on a flow-sensitive alternating inversion recovery (FAIR) spin labeling scheme combined with a single-shot 3D GRASE (gradient-spin echo) readout on a 3 Tesla scanner. Analysis was performed with Statistical Parametric Mapping (SPM 8), using a general linear model for whole brain comparison between the heroin and placebo conditions. We found that compared to placebo, heroin was associated with reduced perfusion in the left anterior cingulate cortex (ACC), the left medial prefrontal cortex (mPFC) and in the insula (both hemispheres). Analysis of extracted perfusion values indicate strong effect sizes and no gender related differences. Reduced perfusion in these brain areas may indicate self- and emotional regulation effects of heroin in maintenance treatment.

  6. Rank-One and Transformed Sparse Decomposition for Dynamic Cardiac MRI

    PubMed Central

    Xiu, Xianchao; Kong, Lingchen

    2015-01-01

    It is challenging and inspiring for us to achieve high spatiotemporal resolutions in dynamic cardiac magnetic resonance imaging (MRI). In this paper, we introduce two novel models and algorithms to reconstruct dynamic cardiac MRI data from under-sampled k − t space data. In contrast to classical low-rank and sparse model, we use rank-one and transformed sparse model to exploit the correlations in the dataset. In addition, we propose projected alternative direction method (PADM) and alternative hard thresholding method (AHTM) to solve our proposed models. Numerical experiments of cardiac perfusion and cardiac cine MRI data demonstrate improvement in performance. PMID:26247010

  7. Assessment of ischemic penumbra in patients with hyperacute stroke using amide proton transfer (APT) chemical exchange saturation transfer (CEST) MRI.

    PubMed

    Tietze, Anna; Blicher, Jakob; Mikkelsen, Irene Klaerke; Østergaard, Leif; Strother, Megan K; Smith, Seth A; Donahue, Manus J

    2014-02-01

    Chemical exchange saturation transfer (CEST)-derived, pH-weighted, amide proton transfer (APT) MRI has shown promise in animal studies for the prediction of infarction risk in ischemic tissue. Here, APT MRI was translated to patients with acute stroke (1-24 h post-symptom onset), and assessments of APT contrast, perfusion, diffusion, disability and final infarct volume (23-92 days post-stroke) are reported. Healthy volunteers (n = 5) and patients (n = 10) with acute onset of symptoms (0-4 h, n = 7; uncertain onset <24 h, n = 3) were scanned with diffusion- and perfusion-weighted MRI, fluid-attenuated inversion recovery (FLAIR) and CEST. Traditional asymmetry and a Lorentzian-based APT index were calculated in the infarct core, at-risk tissue (time-to-peak, TTP; lengthening) and final infarct volume. On average (mean ± standard deviation), control white matter APT values (asymmetry, 0.019 ± 0.005; Lorentzian, 0.045 ± 0.006) were not significantly different (p > 0.05) from APT values in normal-appearing white matter (NAWM) of patients (asymmetry, 0.022 ± 0.003; Lorentzian, 0.048 ± 0.003); however, ischemic regions in patients showed reduced (p = 0.03) APT effects compared with NAWM. Representative cases are presented, whereby the APT contrast is compared quantitatively with contrast from other imaging modalities. The findings vary between patients; in some patients, a trend for a reduction in the APT signal in the final infarct region compared with at-risk tissue was observed, consistent with tissue acidosis. However, in other patients, no relationship was observed in the infarct core and final infarct volume. Larger clinical studies, in combination with focused efforts on sequence development at clinically available field strengths (e.g. 3.0 T), are necessary to fully understand the potential of APT imaging for guiding the hyperacute management of patients.

  8. Uterine cirsoid aneurysm: MRI and MRA

    SciTech Connect

    Joja, Ikuo; Asakawa, Mari; Motoyama, Kazumi

    1996-03-01

    Uterine cirsoid aneurysm is uncommon. It is important to make a diagnosis of this disease preoperatively, because repeated curettages may induce life-threatening massive genital bleeding. We present a case of a 51-year-old woman with uterine cirsoid aneurysm in whom MRI and MRA were very useful for the preoperative diagnosis. The radiologic appearances on ultrasonography, CT, conventional SE MRI, MRA, dynamic MRI, and pelvic angiography are presented. Conventional SE T1-weighted and T2-weighted images demonstrated multiple flow voids in the uterus and bilateral adnexal regions. MRA demonstrated a cluster of distinct, tortuous, and coiled vascular channels in the pelvis. MRA could obtain images almost equal to angiography and was considered to be an excellent noninvasive imaging technique for the diagnosis of uterine cirsoid aneurysm. 28 refs., 7 figs

  9. The Mouse Isolated Perfused Kidney Technique.

    PubMed

    Czogalla, Jan; Schweda, Frank; Loffing, Johannes

    2016-11-17

    The mouse isolated perfused kidney (MIPK) is a technique for keeping a mouse kidney under ex vivo conditions perfused and functional for 1 hr. This is a prerequisite for studying the physiology of the isolated organ and for many innovative applications that may be possible in the future, including perfusion decellularization for kidney bioengineering or the administration of anti-rejection or genome-editing drugs in high doses to prime the kidney for transplantation. During the time of the perfusion, the kidney can be manipulated, renal function can be assessed, and various pharmaceuticals administered. After the procedure, the kidney can be transplanted or processed for molecular biology, biochemical analysis, or microscopy. This paper describes the perfusate and the surgical technique needed for the ex vivo perfusion of mouse kidneys. Details of the perfusion apparatus are given and data are presented showing the viability of the kidney's preparation: renal blood flow, vascular resistance, and urine data as functional, transmission electron micrographs of different nephron segments as morphological readouts, and western blots of transport proteins of different nephron segments as molecular readout.

  10. Extended Anatomical Grading in Diffuse Axonal Injury Using MRI: Hemorrhagic Lesions in the Substantia Nigra and Mesencephalic Tegmentum Indicate Poor Long-Term Outcome

    PubMed Central

    Marklund, Niklas; Lannsjö, Marianne; Howells, Tim; Raininko, Raili; Wikström, Johan; Enblad, Per

    2017-01-01

    Abstract Clinical outcome after traumatic diffuse axonal injury (DAI) is difficult to predict. In this study, three magnetic resonance imaging (MRI) sequences were used to quantify the anatomical distribution of lesions, to grade DAI according to the Adams grading system, and to evaluate the value of lesion localization in combination with clinical prognostic factors to improve outcome prediction. Thirty patients (mean 31.2 years ±14.3 standard deviation) with severe DAI (Glasgow Motor Score [GMS] <6) examined with MRI within 1 week post-injury were included. Diffusion-weighted (DW), T2*-weighted gradient echo and susceptibility-weighted (SWI) sequences were used. Extended Glasgow outcome score was assessed after 6 months. Number of DW lesions in the thalamus, basal ganglia, and internal capsule and number of SWI lesions in the mesencephalon correlated significantly with outcome in univariate analysis. Age, GMS at admission, GMS at discharge, and low proportion of good monitoring time with cerebral perfusion pressure <60 mm Hg correlated significantly with outcome in univariate analysis. Multivariate analysis revealed an independent relation with poor outcome for age (p = 0.005) and lesions in the mesencephalic region corresponding to substantia nigra and tegmentum on SWI (p = 0.008). We conclude that higher age and lesions in substantia nigra and mesencephalic tegmentum indicate poor long-term outcome in DAI. We propose an extended MRI classification system based on four stages (stage I—hemispheric lesions, stage II—corpus callosum lesions, stage III—brainstem lesions, and stage IV—substantia nigra or mesencephalic tegmentum lesions); all are subdivided by age (≥/<30 years). PMID:27356857

  11. MRI findings of benign monomelic amyotrophy of lower limb.

    PubMed

    Hamano, T; Mutoh, T; Hirayama, M; Ito, K; Kimura, M; Aita, T; Kiyosawa, K; Ohtaki, T; Kuriyama, M

    1999-06-01

    We report here magnetic resonance imaging (MRI) findings of two patients with benign monomelic amyotrophy of lower limb. Both subjects showed unilateral amyotrophy of the lower limb with a benign clinical course, and the affected muscles demonstrated neurogenic changes. On T1- and T2-weighted MRI, marked atrophy and increased signal intensity were found mainly in gastrocnemius and soleus muscles. Moreover, MRI examination also revealed that thigh muscles including semitendinosus, semimembranosus, and vastus intermedius and lateralis muscles were involved in one of the patients. We concluded that muscle MRI is very useful for detecting affected muscles, especially deep skeletal muscles in patients with benign monomelic amyotrophy of lower limb.

  12. Ventilation-perfusion imaging in pulmonary papillomatosis

    SciTech Connect

    Espinola, D.; Rupani, H.; Camargo, E.E.; Wagner, H.N. Jr.

    1981-11-01

    Three children with laryngeal papillomas involving the lungs had serial ventilation-perfusion scintigrams to assess results of therapy designed to reduce the bronchial involvement. Different imaging patterns were observed depending on size, number, and location of lesions. In early parenchymal involvement a ventilation-perfusion mismatch was seen. The initial and follow-up studies correlated well with clinical and radiographic findings. This noninvasive procedure is helpful in evaluating ventilatory and perfusion impairment in these patients as well as their response to treatment.

  13. Cochlear perfusion with a viscous fluid.

    PubMed

    Wang, Yi; Olson, Elizabeth S

    2016-07-01

    The flow of viscous fluid in the cochlea induces shear forces, which could provide benefit in clinical practice, for example to guide cochlear implant insertion or produce static pressure to the cochlear partition or wall. From a research standpoint, studying the effects of a viscous fluid in the cochlea provides data for better understanding cochlear fluid mechanics. However, cochlear perfusion with a viscous fluid may damage the cochlea. In this work we studied the physiological and anatomical effects of perfusing the cochlea with a viscous fluid. Gerbil cochleae were perfused at a rate of 2.4 μL/min with artificial perilymph (AP) and sodium hyaluronate (Healon, HA) in four different concentrations (0.0625%, 0.125%, 0.25%, 0.5%). The different HA concentrations were applied either sequentially in the same cochlea or individually in different cochleae. The perfusion fluid entered from the round window and was withdrawn from basal scala vestibuli, in order to perfuse the entire perilymphatic space. Compound action potentials (CAP) were measured after each perfusion. After perfusion with increasing concentrations of HA in the order of increasing viscosity, the CAP thresholds generally increased. The threshold elevation after AP and 0.0625% HA perfusion was small or almost zero, and the 0.125% HA was a borderline case, while the higher concentrations significantly elevated CAP thresholds. Histology of the cochleae perfused with the 0.0625% HA showed an intact Reissner's membrane (RM), while in cochleae perfused with 0.125% and 0.25% HA RM was torn. Thus, the CAP threshold elevation was likely due to the broken RM, likely caused by the shear stress produced by the flow of the viscous fluid. Our results and analysis indicate that the cochlea can sustain, without a significant CAP threshold shift, up to a 1.5 Pa shear stress. Beside these finding, in the 0.125% and 0.25% HA perfusion cases, a temporary CAP threshold shift was observed, perhaps due to the presence and

  14. [MRI evaluation of cervicothoracic CSF hypotension].

    PubMed

    Maraval, A; Brugieres, P; Combes, C; Thomas, P; Blanc, R; Gaston, A

    2006-06-01

    We propose studying signs of cervicothoracic CSF hypotension by MRI. Axial T1-weighted GRE sequence with and without saturation bands positioned above and below the selected image plane, MR venography and MR Angiography with contrast administration are helpful to confirm the venous nature of the epidural thickening and to make the differential diagnosis with infectious or neoplastic epiduritis.

  15. Computed tomography perfusion imaging denoising using Gaussian process regression

    NASA Astrophysics Data System (ADS)

    Zhu, Fan; Carpenter, Trevor; Rodriguez Gonzalez, David; Atkinson, Malcolm; Wardlaw, Joanna

    2012-06-01

    Brain perfusion weighted images acquired using dynamic contrast studies have an important clinical role in acute stroke diagnosis and treatment decisions. However, computed tomography (CT) images suffer from low contrast-to-noise ratios (CNR) as a consequence of the limitation of the exposure to radiation of the patient. As a consequence, the developments of methods for improving the CNR are valuable. The majority of existing approaches for denoising CT images are optimized for 3D (spatial) information, including spatial decimation (spatially weighted mean filters) and techniques based on wavelet and curvelet transforms. However, perfusion imaging data is 4D as it also contains temporal information. Our approach using Gaussian process regression (GPR), which takes advantage of the temporal information, to reduce the noise level. Over the entire image, GPR gains a 99% CNR improvement over the raw images and also improves the quality of haemodynamic maps allowing a better identification of edges and detailed information. At the level of individual voxel, GPR provides a stable baseline, helps us to identify key parameters from tissue time-concentration curves and reduces the oscillations in the curve. GPR is superior to the comparable techniques used in this study.

  16. Myocardial perfusion distribution and coronary arterial pressure and flow signals: clinical relevance in relation to multiscale modeling, a review.

    PubMed

    Nolte, Froukje; Hyde, Eoin R; Rolandi, Cristina; Lee, Jack; van Horssen, Pepijn; Asrress, Kal; van den Wijngaard, Jeroen P H M; Cookson, Andrew N; van de Hoef, Tim; Chabiniok, Radomir; Razavi, Reza; Michler, Christian; Hautvast, Gilion L T F; Piek, Jan J; Breeuwer, Marcel; Siebes, Maria; Nagel, Eike; Smith, Nic P; Spaan, Jos A E

    2013-11-01

    Coronary artery disease, CAD, is associated with both narrowing of the epicardial coronary arteries and microvascular disease, thereby limiting coronary flow and myocardial perfusion. CAD accounts for almost 2 million deaths within the European Union on an annual basis. In this paper, we review the physiological and pathophysiological processes underlying clinical decision making in coronary disease as well as the models for interpretation of the underlying physiological mechanisms. Presently, clinical decision making is based on non-invasive magnetic resonance imaging, MRI, of myocardial perfusion and invasive coronary hemodynamic measurements of coronary pressure and Doppler flow velocity signals obtained during catheterization. Within the euHeart project, several innovations have been developed and applied to improve diagnosis-based understanding of the underlying biophysical processes. Specifically, MRI perfusion data interpretation has been advanced by the gradientogram, a novel graphical representation of the spatiotemporal myocardial perfusion gradient. For hemodynamic data, functional indices of coronary stenosis severity that do not depend on maximal vasodilation are proposed and the Valsalva maneuver for indicating the extravascular resistance component of the coronary circulation has been introduced. Complementary to these advances, model innovation has been directed to the porous elastic model coupled to a one-dimensional model of the epicardial arteries. The importance of model development is related to the integration of information from different modalities, which in isolation often result in conflicting treatment recommendations.

  17. Evolution of pulmonary perfusion defects demonstrated with contrast-enhanced dynamic MR perfusion imaging.

    PubMed

    Howarth, N R; Beziat, C; Berthezène, Y

    1999-01-01

    Pulmonary perfusion defects can be demonstrated with contrast-enhanced dynamic MR perfusion imaging. We present the case of a patient with a pulmonary artery sarcoma who presented with a post-operative pulmonary embolus and was followed in the post-operative period with dynamic contrast-enhanced MR perfusion imaging. This technique allows rapid imaging of the first passage of contrast material through the lung after bolus injection in a peripheral vein. To our knowledge, this case report is the first to describe the use of this MR technique in showing the evolution of peripheral pulmonary perfusion defects associated with pulmonary emboli.

  18. MRI manifestations of bowler's thumb.

    PubMed

    Showalter, Martha F; Flemming, Donald J; Bernard, Stephanie A

    2011-01-01

    Bowler's thumb is a rare perineural fibrosis involving the ulnar digital nerve of the thumb. Affected patients present with pain, neuropathy, and mass lesion. The condition is caused by chronic repetitive impaction of the ulnar soft tissues of the thumb against the thumbhole of a bowling ball. In our case, MRI showed decreased signal intensity on both T1- and T2-weighted images surrounding an enlarged ulnar digital nerve of the thumb. The findings can be confused with giant-cell tumor of the tendon sheath or peripheral-nerve-sheath tumor.

  19. Enhanced task related brain activation and resting perfusion in healthy older adults after chronic blueberry supplementation.

    PubMed

    Bowtell, Joanna L; Aboo-Bakkar, Zainie; Conway, Myra; Adlam, Anna-Lynne R; Fulford, Jonathan

    2017-03-01

    Blueberries are rich in flavonoids, which possess antioxidant and anti-inflammatory properties. High flavonoid intakes attenuate age-related cognitive decline, but data from human intervention studies are sparse. We investigated whether 12 weeks of blueberry concentrate supplementation improved brain perfusion, task-related activation and cognitive function in healthy older adults. Participants were randomised to consume either 30 ml blueberry concentrate providing 387 mg anthocyanidins (5 female, 7 male; age 67.5±3.0 y; BMI, 25.9±3.3 kg.m-2) or isoenergetic placebo (8 female, 6 male; age 69.0 ±3.3 y; BMI, 27.1±.4.0 kg.m-2). Pre- and post-supplementation, participants undertook a battery of cognitive function tests and a numerical Stroop test within a 1.5T MRI scanner while functional magnetic resonance images (fMRI) were continuously acquired. Quantitative resting brain perfusion was determined using an arterial spin labelling (ASL) technique, and blood biomarkers of inflammation and oxidative stress were measured. Significant increases in brain activity were observed in response to blueberry supplementation relative to the placebo group within Brodmann areas 4/6/10/21/40/44/45, precuneus, anterior cingulate, and insula/thalamus (p<0.001), as well as significant improvements in grey matter perfusion in the parietal (5.0±1.8 vs -2.9±2.4 %, p=0.013) and occipital (8.0±2.6 vs -0.7±3.2 %, p=0.031) lobes. There was also evidence suggesting improvement in working memory (two back test) after blueberry versus placebo supplementation (p=0.05). Supplementation with an anthocyanin rich blueberry concentrate improved brain perfusion and activation in brain areas associated with cognitive function in healthy older adults.

  20. Is the cerebellum the optimal reference region for intensity normalization of perfusion MR studies in early Alzheimer's disease?

    PubMed

    Lacalle-Aurioles, María; Alemán-Gómez, Yasser; Guzmán-De-Villoria, Juan Adán; Cruz-Orduña, Isabel; Olazarán, Javier; Mateos-Pérez, José María; Martino, María Elena; Desco, Manuel

    2013-01-01

    The cerebellum is the region most commonly used as a reference when normalizing the intensity of perfusion images acquired using magnetic resonance imaging (MRI) in Alzheimer's disease (AD) studies. In addition, the cerebellum provides unbiased estimations with nuclear medicine techniques. However, no reports confirm the cerebellum as an optimal reference region in MRI studies or evaluate the consequences of using different normalization regions. In this study, we address the effect of using the cerebellum, whole-brain white matter, and whole-brain cortical gray matter in the normalization of cerebral blood flow (CBF) parametric maps by comparing patients with stable mild cognitive impairment (MCI), patients with AD and healthy controls. According to our results, normalization by whole-brain cortical gray matter enables more sensitive detection of perfusion abnormalities in AD patients and reveals a larger number of affected regions than data normalized by the cerebellum or whole-brain white matter. Therefore, the cerebellum is not the most valid reference region in MRI studies for early stages of AD. After normalization by whole-brain cortical gray matter, we found a significant decrease in CBF in both parietal lobes and an increase in CBF in the right medial temporal lobe. We found no differences in perfusion between patients with stable MCI and healthy controls either before or after normalization.

  1. Is the Cerebellum the Optimal Reference Region for Intensity Normalization of Perfusion MR Studies in Early Alzheimer’s Disease?

    PubMed Central

    Lacalle-Aurioles, María; Alemán-Gómez, Yasser; Guzmán-De-Villoria, Juan Adán; Cruz-Orduña, Isabel; Olazarán, Javier; Mateos-Pérez, José María; Martino, María Elena; Desco, Manuel

    2013-01-01

    The cerebellum is the region most commonly used as a reference when normalizing the intensity of perfusion images acquired using magnetic resonance imaging (MRI) in Alzheimer’s disease (AD) studies. In addition, the cerebellum provides unbiased estimations with nuclear medicine techniques. However, no reports confirm the cerebellum as an optimal reference region in MRI studies or evaluate the consequences of using different normalization regions. In this study, we address the effect of using the cerebellum, whole-brain white matter, and whole-brain cortical gray matter in the normalization of cerebral blood flow (CBF) parametric maps by comparing patients with stable mild cognitive impairment (MCI), patients with AD and healthy controls. According to our results, normalization by whole-brain cortical gray matter enables more sensitive detection of perfusion abnormalities in AD patients and reveals a larger number of affected regions than data normalized by the cerebellum or whole-brain white matter. Therefore, the cerebellum is not the most valid reference region in MRI studies for early stages of AD. After normalization by whole-brain cortical gray matter, we found a significant decrease in CBF in both parietal lobes and an increase in CBF in the right medial temporal lobe. We found no differences in perfusion between patients with stable MCI and healthy controls either before or after normalization. PMID:24386081

  2. Comparative studies on the toxicity of mercury, cadmium, and copper toward the isolated perfused rat liver.

    PubMed

    Strubelt, O; Kremer, J; Tilse, A; Keogh, J; Pentz, R; Younes, M

    1996-02-23

    The toxic effects of cadmium, mercury, and copper were compared over the over range 0.01, 0.03, and 0.1 mM using the isolated perfused rat liver preparation. All metals caused similar changes in various parameters used to describe general toxicity. Thus reductions in oxygen consumption, perfusion flow, and biliary secretion were found, while lactate dehydrogenase release into the perfusate, as well as liver weight, increased also in a dose-dependent fashion. Each metal caused similar magnitudes of changes and exerted similar potency. Measurement of other parameters indicating more specific injury revealed a number of differences. Although all metals reduced hepatic ATP concentration, mercury and cadmium were more potent than copper in this respect. Cadmium was the most potent at decreasing reduced glutathione levels. Mercury was most effective at increasing tissue calcium content, while copper was less so, and cadmium ineffective. Only copper significantly increased tissue malondialdehyde (MDA) content, while all metals increased its release into perfusate. Furthermore, whereas cadmium seemed the most potent metal in increasing MDA release, it was least efficacious, while copper was the most. Antioxidants such as superoxide dismutase, catalase, and Trolox C only reduced cadmium's influence on MDA in perfusate; however, they did not affect cadmium's ability to alter most other parameters of vitality. Albumin reversed the toxic effects of copper and mercury, but not cadmium. While metal-induced reductions in perfusion flow accounted for some of the toxic effects of the metals investigated, the results as