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Sample records for observations comparing mdct

  1. Utility of Postmortem Autopsy via Whole-Body Imaging: Initial Observations Comparing MDCT and 3.0T MRI Findings with Autopsy Findings

    PubMed Central

    Cha, Jang Gyu; Kim, Dong Hun; Kim, Dae Ho; Paik, Sang Hyun; Park, Jai Soung; Park, Seong Jin; Lee, Hae Kyung; Hong, Hyun Sook; Choi, Duek Lin; Chung, Nak Eun; Lee, Bong Woo; Seo, Joong Seok

    2010-01-01

    Objective We prospectively compared whole-body multidetector computed tomography (MDCT) and 3.0T magnetic resonance (MR) images with autopsy findings. Materials and Methods Five cadavers were subjected to whole-body, 16-channel MDCT and 3.0T MR imaging within two hours before an autopsy. A radiologist classified the MDCT and 3.0T MRI findings into major and minor findings, which were compared with autopsy findings. Results Most of the imaging findings, pertaining to head and neck, heart and vascular, chest, abdomen, spine, and musculoskeletal lesions, corresponded to autopsy findings. The causes of death that were determined on the bases of MDCT and 3.0T MRI findings were consistent with the autopsy findings in four of five cases. CT was useful in diagnosing fatal hemorrhage and pneumothorax, as well as determining the shapes and characteristics of the fractures and the direction of external force. MRI was effective in evaluating and tracing the route of a metallic object, soft tissue lesions, chronicity of hemorrhage, and bone bruises. Conclusion A postmortem MDCT combined with MRI is a potentially powerful tool, providing noninvasive and objective measurements for forensic investigations. PMID:20592923

  2. MR-Imaging of teeth and periodontal apparatus: an experimental study comparing high-resolution MRI with MDCT and CBCT.

    PubMed

    Gaudino, Chiara; Cosgarea, Raluca; Heiland, Sabine; Csernus, Réka; Beomonte Zobel, Bruno; Pham, Mirko; Kim, Ti-Sun; Bendszus, Martin; Rohde, Stefan

    2011-12-01

    The aim of this study was (1) to assess the ability of magnetic resonance imaging (MRI) to visualize dental and periodontal structures and (2) to compare findings with multidetector computed tomography (MDCT) and cone beam CT (CBCT). Four porcine mandibles were examined with (1) 3T-MRI, (2) MDCT and (3) CBCT. Two observers independently reviewed MR, MDCT and CBCT images and assessed image quality of different dental and periodontal structures. To assess quantitatively the accuracy of the different imaging technique, both observers measured burr holes, previously drilled in the mandibles. Dental structures, e.g. teeth roots, pulpa chamber and dentin, were imaged accurately with all imaging sources. Periodontal space and cortical/trabecular bone were better visualized by MRI (p < 0.001). MRI could excellently display the lamina dura, not detectable with MDCT and only inconstant visible with CBCT (p < 0.001). Burr hole measurements were highly precise with all imaging techniques. This experimental study shows the diagnostic feasibility of MRI in visualization of teeth and periodontal anatomy. Detection of periodontal structures was significantly better with MRI than with MDCT or CBCT. Prospective trials have to evaluate further the potential benefit of MRI in a clinical setting.

  3. Diagnostic performance of 64-MDCT and 1.5-T MRI with high-resolution sequences in the T staging of gastric cancer: a comparative analysis with histopathology.

    PubMed

    Anzidei, M; Napoli, A; Zaccagna, F; Di Paolo, P; Zini, C; Cavallo Marincola, B; Geiger, D; Catalano, C; Passariello, R

    2009-10-01

    This study was undertaken to compare the accuracy of magnetic resonance (MR) imaging and 64-slice multidetector computed tomography (64-MDCT) in the T staging of gastric carcinoma in comparison with histopathology. Forty patients with an endoscopic diagnosis of gastric carcinoma underwent preoperative MR imaging and 64-MDCT, both of which were performed after i.v. injection of scopolamine and water distension of the stomach. In the MR imaging protocol, we acquired T2-weighted turbo spin-echo (TSE) sequences, true fast imaging steady-state free precession (true-FISP) and gadolinium-enhanced T1-weighted volumetric interpolated breath-hold examination (VIBE) 3D sequences. Contrastenhanced CT scans were obtained in the arterial and venous phases. Two groups of radiologists independently reviewed the MR and 64-MDCT images. The results were compared with pathology findings. In the evaluation of T stage, 64-MDCT had 82.5% and MR imaging had 80% sensitivity. Accuracy of MR imaging was slightly higher than that of 64-MDCT in identifying T1 lesions (50% vs 37.5%), whereas the accuracy of 64-MDCT was higher in differentiating T2 lesions (81.2% vs 68.7%). The accuracy of MR imaging and 64-MDCT did not differ significantly in the evaluation of T3-T4 lesions (p>0.05). Understaging was observed in 20% of cases with MR imaging and in 17.5% with 64-MDCT. MR imaging and 64-MDCT accuracy levels did not differ in advanced stages of disease, whereas MR imaging was superior in identifying early stages of gastric cancer and can be considered a valid alternative to MDCT in clinical practice.

  4. Underestimation of left atrial size measured with transthoracic echocardiography compared with 3D MDCT.

    PubMed

    Koka, Anish R; Yau, James; Van Why, Carolyn; Cohen, Ira S; Halpern, Ethan J

    2010-05-01

    High-resolution 64-MDCT images of the beating heart can be used for measurement of left atrial volume with 3D chamber reconstruction. The purpose of this study was to correlate measurements of left atrial volume obtained with clinical transthoracic echocardiography (TTE) and measurements obtained with 64-MDCT 3D reconstructions of the left atrium. Patients who underwent TTE and MDCT within 3 days were identified. TTE images were graded as excellent, good, or suboptimal. Two independent observers calculated estimates of left atrial volume from TTE and 64-MDCT images using 3D chamber reconstructions and conventional geometric assumptions on MDCT echocardiographic views. MDCT estimates of phantom volume on 3D chamber reconstructions agreed with actual volumes within 1.5%. The TTE images of 37 of the 52 patients were judged to be of good or excellent quality and were included in the analysis. Mean left atrial volume measured on 3D chamber reconstructions was 61 +/- 14 mL/m(2). Estimates of left atrial volume obtained with TTE were significantly lower (28 +/- 12 mL/m(2)) than similar estimates obtained with MDCT echocardiographic views (53 +/- 15 mL/m(2)) (p < 0.001). TTE left atrial volume and 3D chamber reconstruction left atrial volume exhibited moderate correlation (r = 0.60-0.70), but the correlation improved when analysis was limited to the 26 studies with excellent-quality TTE images (r = 0.71). MDCT echocardiographic estimates of left atrial volume with the area-length method had excellent correlation (r = 0.89) with and were closest to estimates made on 3D chamber reconstructions. Left atrial volume is significantly underestimated on TTE images, and TTE estimates have moderate correlation with left atrial volume measured with MDCT. Measured and estimated left atrial volumes at MDCT can provide important additive prognostic information in the care of patients undergoing MDCT for other reasons. Future studies are needed to obtain normative MDCT measurements of

  5. Spectrum of Abdominal Aortic Disease in a Tertiary Health Care Setup: MDCT Based Observational Study

    PubMed Central

    Kumar, DG Santosh; Gadabanahalli, Karthik; Kalyanpur, Arjun

    2016-01-01

    considered for surgical treatment. Ten patients with dissection underwent endovascular procedure. Rest of the patients was managed conservatively. Conclusion Aortic disease was observed in 43% of investigated patients. Atherosclerosis with and without aortic aneurysm constituted the largest group. MDCT provided comprehensive information about the lesion and associated complications. In view of the wider availability and desired imaging qualities, MDCT provided optimal information for diagnosis and management of aortic pathology. Majority of our patients (90%) were treated conservatively. PMID:28050476

  6. Accuracy of Monte Carlo simulations compared to in-vivo MDCT dosimetry

    SciTech Connect

    Bostani, Maryam McMillan, Kyle; Cagnon, Chris H.; McNitt-Gray, Michael F.; Mueller, Jonathon W.; Cody, Dianna D.; DeMarco, John J.

    2015-02-15

    Purpose: The purpose of this study was to assess the accuracy of a Monte Carlo simulation-based method for estimating radiation dose from multidetector computed tomography (MDCT) by comparing simulated doses in ten patients to in-vivo dose measurements. Methods: MD Anderson Cancer Center Institutional Review Board approved the acquisition of in-vivo rectal dose measurements in a pilot study of ten patients undergoing virtual colonoscopy. The dose measurements were obtained by affixing TLD capsules to the inner lumen of rectal catheters. Voxelized patient models were generated from the MDCT images of the ten patients, and the dose to the TLD for all exposures was estimated using Monte Carlo based simulations. The Monte Carlo simulation results were compared to the in-vivo dose measurements to determine accuracy. Results: The calculated mean percent difference between TLD measurements and Monte Carlo simulations was −4.9% with standard deviation of 8.7% and a range of −22.7% to 5.7%. Conclusions: The results of this study demonstrate very good agreement between simulated and measured doses in-vivo. Taken together with previous validation efforts, this work demonstrates that the Monte Carlo simulation methods can provide accurate estimates of radiation dose in patients undergoing CT examinations.

  7. Abdominal rapid-kVp-switching dual-energy MDCT with reduced IV contrast compared to conventional MDCT with standard weight-based IV contrast: an intra-patient comparison.

    PubMed

    Clark, Zachary E; Bolus, David N; Little, Mark D; Morgan, Desiree E

    2015-04-01

    Perform intra-patient comparison of attenuation values on lower keV dual-energy abdominal CT images using reduced IV contrast dose compared to conventional single energy polychromatic beam abdominal MDCT images using standard IV contrast dose. IRB approved retrospective evaluation of consecutive adults who had both standard IV contrast dosage conventional multiphasic MDCT (SECT) and reduced IV contrast dosage rapid kV-switching dual-energy multiphasic MDCT (rsDECT) of the abdomen. Arterial phase dual-energy 52, 70 and 78 keV simulated monoenergetic HU were compared (t test) to arterial phase SECT HU for: aorta, liver, pancreas, psoas, and hepatic/pancreatic tumors. Contrast to noise ratios (CNR), IV contrast dose reduction and dose-length product (DLP) were recorded. Two blinded independent readers evaluated the CT datasets for subjective image quality based on a five point scale. Twenty-nine scan pairs in 24 subjects (13 M, mean age 64, weight 76.7 kg) were evaluated. Mean reduction in IV contrast dose was 37 %. Mean ± SD HU on 52 keV rsDECT vs. SECT were: aorta 534 ± 138 vs. 271 ± 69; liver 88 ± 24 vs. 67 ± 16; pancreas 140 ± 60 vs. 89 ± 40; psoas 63 ± 15 vs. 50 ± 12 (all p < 0.001). Noise was higher for 52 keV compared to SECT (p < 0.001); CNRs were not significantly different. Mean ± SD DLP for rsDECT was 1421 ± 563 and SECT 1335 ± 562 mGy·cm (p = 0.640). For tumor vs. nontumoral parenchyma, mean absolute contrast difference was 58.4 HU on 52 keV, and 29.0 HU on SECT. Nearly all images were rated as good or excellent and there were no statistically significant differences in image quality between the DECT and SECT images. Statistically significant gains in vascular and parenchymal enhancement without adverse effect on CNR or lesion contrast were observed in this intra-patient comparison using reduced IV contrast dose rsDECT compared to standard weight-based IV dose conventional SECT.

  8. Patient Characteristics as Predictors of Image Quality and Diagnostic Accuracy of MDCT Compared With Conventional Coronary Angiography for Detecting Coronary Artery Stenoses: CORE-64 Multicenter International Trial

    PubMed Central

    Dewey, Marc; Vavere, Andrea L.; Arbab-Zadeh, Armin; Miller, Julie M.; Sara, Leonardo; Cox, Christopher; Gottlieb, Ilan; Yoshioka, Kunihiro; Paul, Narinder; Hoe, John; de Roos, Albert; Lardo, Albert C.; Lima, Joao A.; Clouse, Melvin E.

    2012-01-01

    OBJECTIVE The purpose of the study was to investigate patient characteristics associated with image quality and their impact on the diagnostic accuracy of MDCT for the detection of coronary artery stenosis. MATERIALS AND METHODS Two hundred ninety-one patients with a coronary artery calcification (CAC) score of ≤ 600 Agatston units (214 men and 77 women; mean age, 59.3 ± 10.0 years [SD]) were analyzed. An overall image quality score was derived using an ordinal scale. The accuracy of quantitative MDCT to detect significant (≥ 50%) stenoses was assessed using quantitative coronary angiography (QCA) per patient and per vessel using a modified 19-segment model. The effect of CAC, obesity, heart rate, and heart rate variability on image quality and accuracy were evaluated by multiple logistic regression. Image quality and accuracy were further analyzed in subgroups of significant predictor variables. Diagnostic analysis was determined for image quality strata using receiver operating characteristic (ROC) curves. RESULTS Increasing body mass index (BMI) (odds ratio [OR] = 0.89, p < 0.001), increasing heart rate (OR = 0.90, p < 0.001), and the presence of breathing artifact (OR = 4.97, p ≤ 0.001) were associated with poorer image quality whereas sex, CAC score, and heart rate variability were not. Compared with examinations of white patients, studies of black patients had significantly poorer image quality (OR = 0.58, p = 0.04). At a vessel level, CAC score (10 Agatston units) (OR = 1.03, p = 0.012) and patient age (OR = 1.02, p = 0.04) were significantly associated with the diagnostic accuracy of quantitative MDCT compared with QCA. A trend was observed in differences in the areas under the ROC curves across image quality strata at the vessel level (p = 0.08). CONCLUSION Image quality is significantly associated with patient ethnicity, BMI, mean scan heart rate, and the presence of breathing artifact but not with CAC score at a patient level. At a vessel level

  9. MDCT assessment of CAD in type-2 diabetic subjects with diabetic neuropathy: the role of Charcot neuro-arthropathy.

    PubMed

    Marano, Riccardo; Pitocco, Dario; Di Stasio, Enrico; Savino, Giancarlo; Merlino, Biagio; Trani, Carlo; Pirro, Federica; Rutigliano, Claudia; Santangelo, Carolina; Minoiu, Aurelian Costin; Natale, Luigi; Bonomo, Lorenzo

    2016-03-01

    To compare the CACS and CAD severity assessed by MDCT in neuropathic type-2 diabetic patients with and without Charcot-neuroarthropathy (CN). Thirty-four CN asymptomatic-patients and 36 asymptomatic-patients with diabetic-neuropathy (DN) without CN underwent MDCT to assess CACS and severity of CAD. Patients were classified as positive for significant CAD in presence of at least one stenosis >50 % on MDCT-coronary-angiography (MDCT-CA). Groups were matched for age, sex and traditional CAD risk-factors. The coronary-angiography (CA) was performed in all patients with at least a significant stenosis detected by MDCT-CA, both as reference and eventually as treatment. CN patients showed higher rates of significant CAD in comparison with DN subjects [p < 0.001], while non-significant differences were observed in CACS (p = 0.980). No significant differences were also observed in CACS distribution in all subjects for stenosis ≥/<50 % (p = 0.814), as well as in both groups (p = 0.661 and 0.559, respectively). The MDCT-CA showed an overall diagnostic-accuracy for significant CAD of 87%. These preliminary data suggest that CN-patients have a higher prevalence of severe CAD in comparison with DN-patients, while coronary plaques do not exhibit an increased amount of calcium. MDCT may be helpful to assess the CV risk in such asymptomatic type-2-diabetic patients with autonomic-neuropathy. Type 2-diabetic-patients with CN result having more severe coronary artery plaque-burden. MDCT-CA may stratify the CV risk in type 2-diabetic-patients with CN. Adequate diagnostic is mandatory for optimal management of type 2-diabetic-patients with CN.

  10. Hepatic Arterial Configuration in Relation to the Segmental Anatomy of the Liver; Observations on MDCT and DSA Relevant to Radioembolization Treatment

    SciTech Connect

    Hoven, Andor F. van den Leeuwen, Maarten S. van Lam, Marnix G. E. H. Bosch, Maurice A. A. J. van den

    2015-02-15

    PurposeCurrent anatomical classifications do not include all variants relevant for radioembolization (RE). The purpose of this study was to assess the individual hepatic arterial configuration and segmental vascularization pattern and to develop an individualized RE treatment strategy based on an extended classification.MethodsThe hepatic vascular anatomy was assessed on MDCT and DSA in patients who received a workup for RE between February 2009 and November 2012. Reconstructed MDCT studies were assessed to determine the hepatic arterial configuration (origin of every hepatic arterial branch, branching pattern and anatomical course) and the hepatic segmental vascularization territory of all branches. Aberrant hepatic arteries were defined as hepatic arterial branches that did not originate from the celiac axis/CHA/PHA. Early branching patterns were defined as hepatic arterial branches originating from the celiac axis/CHA.ResultsThe hepatic arterial configuration and segmental vascularization pattern could be assessed in 110 of 133 patients. In 59 patients (54 %), no aberrant hepatic arteries or early branching was observed. Fourteen patients without aberrant hepatic arteries (13 %) had an early branching pattern. In the 37 patients (34 %) with aberrant hepatic arteries, five also had an early branching pattern. Sixteen different hepatic arterial segmental vascularization patterns were identified and described, differing by the presence of aberrant hepatic arteries, their respective vascular territory, and origin of the artery vascularizing segment four.ConclusionsThe hepatic arterial configuration and segmental vascularization pattern show marked individual variability beyond well-known classifications of anatomical variants. We developed an individualized RE treatment strategy based on an extended anatomical classification.

  11. Comparison of conventional radiography and MDCT in suspected scaphoid fractures

    PubMed Central

    Behzadi, Cyrus; Karul, Murat; Henes, Frank Oliver; Laqmani, Azien; Catala-Lehnen, Philipp; Lehmann, Wolfgang; Nagel, Hans-Dieter; Adam, Gerhard; Regier, Marc

    2015-01-01

    AIM: To determine the diagnostic accuracy and radiation dose of conventional radiography and multidetector computed tomography (MDCT) in suspected scaphoid fractures. METHODS: One hundred twenty-four consecutive patients were enrolled in our study who had suffered from a wrist trauma and showed typical clinical symptoms suspicious of an acute scaphoid fracture. All patients had initially undergone conventional radiography. Subsequent MDCT was performed within 10 d because of persisting clinical symptoms. Using the MDCT data as the reference standard, a fourfold table was used to classify the test results. The effective dose and impaired energy were assessed in order to compare the radiation burden of the two techniques. The Wilcoxon test was performed to compare the two diagnostic modalities. RESULTS: Conventional radiography showed 34 acute fractures of the scaphoid in 124 patients (42.2%). Subsequent MDCT revealed a total of 42 scaphoid fractures. The sensitivity of conventional radiography for scaphoid fracture detection was 42.8% and its specificity was 80% resulting in an overall accuracy of 59.6%. Conventional radiography was significantly inferior to MDCT (P < 0.01) concerning scaphoid fracture detection. The mean effective dose of MDCT was 0.1 mSv compared to 0.002 mSv of conventional radiography. CONCLUSION: Conventional radiography is insufficient for accurate scaphoid fracture detection. Regarding the almost negligible effective dose, MDCT should serve as the first imaging modality in wrist trauma. PMID:25628802

  12. Simultaneous screening for osteoporosis at CT colonography: bone mineral density assessment using MDCT attenuation techniques compared with the DXA reference standard.

    PubMed

    Pickhardt, Perry J; Lee, Lawrence J; del Rio, Alejandro Muñoz; Lauder, Travis; Bruce, Richard J; Summers, Ron M; Pooler, B Dustin; Binkley, Neil

    2011-09-01

    The purpose of this study was to evaluate the utility of lumbar spine attenuation measurement for bone mineral density (BMD) assessment at screening computed tomographic colonography (CTC) using central dual-energy X-ray absorptiometry (DXA) as the reference standard. Two-hundred and fifty-two adults (240 women and 12 men; mean age 58.9 years) underwent CTC screening and central DXA BMD measurement within 2 months (mean interval 25.0 days). The lowest DXA T-score between the spine and hip served as the reference standard, with low BMD defined per World Health Organization as osteoporosis (DXA T-score ≤ -2.5) or osteopenia (DXA T-score between -1.0 and -2.4). Both phantomless quantitative computed tomography (QCT) and simple nonangled region-of-interest (ROI) multi-detector CT (MDCT) attenuation measurements were applied to the T(12) -L(5) levels. The ability to predict osteoporosis and low BMD (osteoporosis or osteopenia) by DXA was assessed. A BMD cut-off of 90 mg/mL at phantomless QCT yielded 100% sensitivity for osteoporosis (29 of 29) and a specificity of 63.8% (143 of 224); 87.2% (96 of 110) below this threshold had low BMD and 49.6% (69 of 139) above this threshold had normal BMD at DXA. At L(1) , a trabecular ROI attenuation cut-off of 160 HU was 100% sensitive for osteoporosis (29 of 29), with a specificity of 46.4% (104 of 224); 83.9% (125 of 149) below this threshold had low BMD and 57.5% (59/103) above had normal BMD at DXA. ROI performance was similar at all individual T(12) -L(5) levels. At ROC analysis, AUC for osteoporosis was 0.888 for phantomless QCT [95% confidence interval (CI) 0.780-0.946] and ranged from 0.825 to 0.853 using trabecular ROIs at single lumbar levels (0.864; 95% CI 0.752-0.930 at multivariate analysis). Supine-prone reproducibility was better with the simple ROI method compared with QCT. It is concluded that both phantomless QCT and simple ROI attenuation measurements of the lumbar spine are effective for BMD screening at CTC

  13. MDCT of abdominopelvic oncologic emergencies

    PubMed Central

    Tirumani, Sree Harsha; Gunabushanam, Gowthaman; Chintapalli, Kedar N; Ryan, John G; Reinhold, Caroline

    2013-01-01

    Abstract Acute complications arising in abdominopelvic malignancies represent a unique subset of patients presenting to the emergency room. The acute presentation can be due to complications occurring in the tumor itself or visceral or vascular structures harboring the tumor. Multidetector computed tomography (MDCT) is the investigation of choice in the workup of these patients and enables appropriate and timely management. Management of the complication depends primarily on the extent of the underlying malignancy and the involvement of other viscera. The purpose of this article is to depict the imaging features of these complications on MDCT. PMID:23876309

  14. Evaluating the effect of two different anesthetic protocols on 64-MDCT coronary angiography in dogs

    PubMed Central

    Drees, Randi; Johnson, Rebecca A; Pinkerton, Marie; Del Rio, Alejandro Munoz; Saunders, Jimmy H; François, Christopher J

    2014-01-01

    Heart rate is a major factor influencing diagnostic image quality in computed tomographic coronary artery angiography (MDCT-CA) with an ideal heart rate of 60–65 beats/minute in humans. Using standardized contrast bolus volume, two different clinically applicable anesthetic protocols were compared for effect on cardiovascular parameters and 64-MDCT-CA quality in ten healthy dogs. The protocol using midazolam/fentanyl (A) was hypothesized to result in adequate reduction of heart rate achieving adequate image quality for MDCT-CA studies and having low impact on blood pressure, where as the protocol utilizing dexmedetomidine (B) was expected to result in reduction of heart rate to the target heart range resulting in excellent image quality while possibly showing undesirable effect on the blood pressure values measured. Heart rate was 80.6 ± 7.5bpm with protocol A and 79.2 ± 14.2bpm with protocol B during image acquisition (P=1). R-R intervals allowing for the best depiction of the individual coronary artery segments were found in the end diastolic period and varied between the 70–95% interval. Diagnostic quality was rated excellent, good and moderate in the majority of the segments evaluated, with higher scores given for more proximal segments and lower for more distal segments respectively. Blur was the most commonly observed artifact and most affected the distal segments. There was no significant difference for the optimal reconstruction interval, diagnostic quality and measured length individual segments or proximal diameter of the coronary arteries between both protocols (P=1). Both anesthetic protocols and the standardized bolus volume allow for diagnostic quality coronary 64-MDCT-CA exams. PMID:25065815

  15. Application of MPVR and TL-VR with 64-row MDCT in neonates with congenital EA and distal TEF.

    PubMed

    Wen, Yang; Peng, Yun; Zhai, Ren-You; Li, Ying-Zi

    2011-03-28

    To assess the application of multiple planar volume reconstruction (MPVR) and three-dimensional (3D) transparency lung volume rendering (TL-VR) with 64-row multidetector-row computed tomography (MDCT) in neonates with congenital esophageal atresia (EA) and distal tracheoesophageal fistula (TEF). Twenty neonates (17 boys, 3 girls) with EA and distal TEF at a mean age of 4.6 d (range 1-16 d) were enrolled in this study. A helical scan of 64-row MDCT was performed at the 64 mm × 0.625 mm collimation. EA and TEF were reconstructed with MPVR and TL-VR, respectively. Initial diagnosis of EA was made by chest radiography showing the inserted catheter in the proximal blind-ended esophageal pouch. Manifestations of MDCT images were compared with the findings at surgery. MDCT showed the proximal and distal esophageal pouches in 20 cases. No significant difference was observed in gaps between the proximal and distal esophageal pouches detected by MPVR and TL-VR. The lengths of gaps between the proximal and distal esophageal pouches detected by MPVR and TL-VR correlated well with the findings at surgery (R = 0.87, P < 0.001). The images of MPVR revealed the orifice of TEF in 13 cases, while TL-VR images showed the orifice of TEF in 4 cases. EA and distal TEF can be reconstructed using MPVR and TL-VR of 64-row MDCT, which is a noninvasive technique to demonstrate the distal esophageal pouches and inter-pouch distance in neonates with EA and distal TEF.

  16. Estimation and comparison of the radiation effective dose during coronary computed tomography angiography examinations on single-source 64-MDCT and dual-source 128-MDCT.

    PubMed

    Khoramian, Daryoush; Sistani, Soroush

    2017-09-14

    To estimate and compare the radiation dose associated with coronary computed tomography angiography (CCTA) examinations on two multi-detector CT scanners (MDCT), 64-MDCT and 128-MDCT, in daily practice. Scan parameters of 90 patients undergoing retrospective electrocardiographic gating spiral CCTA exam were recorded during a period on a single-source 64-MDCT and a dual-source 128-MDCT, and average scan parameters were derived that were used for dosimetry. The computed tomography dose index (CTDI) with a pencil ionisation chamber and polymethyl methacrylate body phantom with diameter of 32 cm was measured on both scanners. The dose-length product (DLP) was calculated and the DLP to effective dose conversion factor (for chest scan at 120 kV of 0.014 mSv mGy(-1) cm(-1)) was used to estimate effective dose (ED). Patients' heart rate, scan length, pitch factor, CTDIv, DLP and ED for 128-MDCT were 64 (5) (beats min(-1)), 161 (10) (mm), 0.26, 47 (12) (mGy), 769 (212) (mGy cm) and 10.3 (3.1) (mSv), respectively [mean (one standard deviation)]. Patients' heart rate, scan length, pitch factor, CTDIv, DLP and ED for 64-MDCT were 60 (7) (beats min(-1)), 172 (14) (mm), 0.2, 60 (6) (mGy), 1068 (98) (mGy cm) and 14.9 (1.4) (mSv), respectively. Our results indicated that the CTDIv, DLP and the effective dose with 128-MDCT is significantly lower than with 64-MDCT (p < 0.05). As differences between the exposure parameter mAs on two CT scanners was not significant (p > 0.05) and the kV was constant for both scanners (120 kV), the differences resulted from a shorter scan length on the 128-MDCT and use of a higher pitch factor (0.26 and 0.2 in the 128-MDCT and 64-MDCT, respectively). Comparison with other published studies confirms the findings and indicates methods for reducing patient dose.

  17. [Detection of intraorbital foreign material using MDCT].

    PubMed

    Hoffstetter, P; Friedrich, C; Framme, C; Hoffstetter, M; Zorger, N; Stierstorfer, K; Ross, C; Uller, W; Müller-Wille, R; Rennert, J; Jung, E M; Schreyer, A G

    2011-06-01

    To judge the possibilities of detection of orbital foreign bodies in multidetector CT (MDCT) with a focus on glass slivers. Experimental systematic measuring of Hounsfield Units (HU) of 20 different materials, containing 16 different types of glass with 4 different types of ophthalmic lenses among them. The measurements were performed using a standardized protocol with an orbita phantom being scanned with 16-slice MDCT. Using the resulting density values, the smallest detectable volume was calculated. Using this data we produced slivers of 5 different glass types in the sub-millimeter range and calculated their volume. Those micro-slivers underwent another CT scan using the same protocol as mentioned above to experimentally discern and confirm the detection limit for micro-slivers made of different materials. Glass has comparatively high density values of at least 2000 HU. The density of glasses with strong refraction is significantly higher and reaches up to 12 400 HU. We calculated a minimum detectable volume of 0.07 mm (3) for glass with a density of 2000 HU. Only glass slivers with a density higher than 8300 HU were experimentally detectable in the sub-millimeter range up to a volume as small as 0.01 mm (3). Less dense glass slivers could not be seen, even though their volume was above the theoretically calculated threshold for detection. Due to its high density of at least 2000 HU, glass is usually easily recognizable as an orbital foreign body. The detection threshold depends on the object's density and size and can be as low as 0.01 mm (3) in the case of glass with strong refraction and thus high density. The detection of glass as an orbital foreign body seems to be secure for slivers with a volume of at least 0.2 mm (3) for all types of glass. © Georg Thieme Verlag KG Stuttgart · New York.

  18. Radiation dose measurement for various parameters in MDCT

    NASA Astrophysics Data System (ADS)

    Lee, Chang-Lae; Kim, Hee-Joung; Jeon, Seong Su; Cho, Hyo-Min; Nam, So Ra; Jung, Ji-Young

    2008-03-01

    The MDCT parameters affecting radiation dose include tube voltage, tube current, change of beam collimation, and size of the human body. The purpose of this study was to measure and evaluate radiation dose for MDCT parameters. A comparative analysis of the radiation dose according to before and after the calibration of the ionization chamber was performed. The ionization chamber was used for measuring radiation dose in the MDCT, as well as of CTDI W according to temperature and pressure correction factors in the CT room. As a result, the patient dose of CTDI W values linearly increased as tube voltage and current were increased, and nonlinearly decreased as beam collimation was increased. And the CTDI W value which was reflected calibration factors, as well as correction factors of temperature and pressure, was found to be greater by the range of 0.479 ~ 3.162 mGy in effective radiation dose than the uncorrected value. Also, Under the abdomen routine CT conditions used in hospitals, patient exposure dose showed a difference of a maximum of 0.7 mSv between before and after the application of such factors. These results imply that the calibration of the ion chamber, and the application of temperature and pressure of the CT room are crucial in measuring and calculating patient exposure dose.

  19. Quantitative analysis of the central-chest lymph nodes based on 3D MDCT image data

    NASA Astrophysics Data System (ADS)

    Lu, Kongkuo; Bascom, Rebecca; Mahraj, Rickhesvar P. M.; Higgins, William E.

    2009-02-01

    Lung cancer is the leading cause of cancer death in the United States. In lung-cancer staging, central-chest lymph nodes and associated nodal stations, as observed in three-dimensional (3D) multidetector CT (MDCT) scans, play a vital role. However, little work has been done in relation to lymph nodes, based on MDCT data, due to the complicated phenomena that give rise to them. Using our custom computer-based system for 3D MDCT-based pulmonary lymph-node analysis, we conduct a detailed study of lymph nodes as depicted in 3D MDCT scans. In this work, the Mountain lymph-node stations are automatically defined by the system. These defined stations, in conjunction with our system's image processing and visualization tools, facilitate lymph-node detection, classification, and segmentation. An expert pulmonologist, chest radiologist, and trained technician verified the accuracy of the automatically defined stations and indicated observable lymph nodes. Next, using semi-automatic tools in our system, we defined all indicated nodes. Finally, we performed a global quantitative analysis of the characteristics of the observed nodes and stations. This study drew upon a database of 32 human MDCT chest scans. 320 Mountain-based stations (10 per scan) and 852 pulmonary lymph nodes were defined overall from this database. Based on the numerical results, over 90% of the automatically defined stations were deemed accurate. This paper also presents a detailed summary of central-chest lymph-node characteristics for the first time.

  20. Effect of Low-Dose MDCT and Iterative Reconstruction on Trabecular Bone Microstructure Assessment

    PubMed Central

    Baum, Thomas; Nasirudin, Radin A.; Mei, Kai; Garcia, Eduardo G.; Burgkart, Rainer; Rummeny, Ernst J.; Kirschke, Jan S.; Noël, Peter B.

    2016-01-01

    We investigated the effects of low-dose multi detector computed tomography (MDCT) in combination with statistical iterative reconstruction algorithms on trabecular bone microstructure parameters. Twelve donated vertebrae were scanned with the routine radiation exposure used in our department (standard-dose) and a low-dose protocol. Reconstructions were performed with filtered backprojection (FBP) and maximum-likelihood based statistical iterative reconstruction (SIR). Trabecular bone microstructure parameters were assessed and statistically compared for each reconstruction. Moreover, fracture loads of the vertebrae were biomechanically determined and correlated to the assessed microstructure parameters. Trabecular bone microstructure parameters based on low-dose MDCT and SIR significantly correlated with vertebral bone strength. There was no significant difference between microstructure parameters calculated on low-dose SIR and standard-dose FBP images. However, the results revealed a strong dependency on the regularization strength applied during SIR. It was observed that stronger regularization might corrupt the microstructure analysis, because the trabecular structure is a very small detail that might get lost during the regularization process. As a consequence, the introduction of SIR for trabecular bone microstructure analysis requires a specific optimization of the regularization parameters. Moreover, in comparison to other approaches, superior noise-resolution trade-offs can be found with the proposed methods. PMID:27447827

  1. Segmentation of the central-chest lymph nodes in 3D MDCT images.

    PubMed

    Lu, Kongkuo; Higgins, William E

    2011-09-01

    Central-chest lymph nodes play a vital role in lung-cancer staging. The definition of lymph nodes from three-dimensional (3D) multidetector computed-tomography (MDCT) images, however, remains an open problem. We propose two methods for computer-based segmentation of the central-chest lymph nodes from a 3D MDCT scan: the single-section live wire and the single-click live wire. For the single-section live wire, the user first applies the standard live wire to a single two-dimensional (2D) section after which automated analysis completes the segmentation process. The single-click live wire is similar but is almost completely automatic. Ground-truth studies involving human 3D MDCT scans demonstrate the robustness, efficiency, and intra-observer and inter-observer reproducibility of the methods.

  2. Comparison between MDCT and Grayscale IVUS in a Quantitative Analysis of Coronary Lumen in Segments with or without Atherosclerotic Plaques.

    PubMed

    Falcão, João L A A; Falcão, Breno A A; Gurudevan, Swaminatha V; Campos, Carlos M; Silva, Expedito R; Kalil-Filho, Roberto; Rochitte, Carlos E; Shiozaki, Afonso A; Coelho-Filho, Otavio R; Lemos, Pedro A

    2015-01-27

    Background: The diagnostic accuracy of 64-slice MDCT in comparison with IVUS has been poorly described and is mainly restricted to reports analyzing segments with documented atherosclerotic plaques. Objectives: We compared 64-slice multidetector computed tomography (MDCT) with gray scale intravascular ultrasound (IVUS) for the evaluation of coronary lumen dimensions in the context of a comprehensive analysis, including segments with absent or mild disease. Methods: The 64-slice MDCT was performed within 72 h before the IVUS imaging, which was obtained for at least one coronary, regardless of the presence of luminal stenosis at angiography. A total of 21 patients were included, with 70 imaged vessels (total length 114.6 ± 38.3 mm per patient). A coronary plaque was diagnosed in segments with plaque burden > 40%. Results: At patient, vessel, and segment levels, average lumen area, minimal lumen area, and minimal lumen diameter were highly correlated between IVUS and 64-slice MDCT (p < 0.01). However, 64-slice MDCT tended to underestimate the lumen size with a relatively wide dispersion of the differences. The comparison between 64-slice MDCT and IVUS lumen measurements was not substantially affected by the presence or absence of an underlying plaque. In addition, 64-slice MDCT showed good global accuracy for the detection of IVUS parameters associated with flow-limiting lesions. Conclusions: In a comprehensive, multi-territory, and whole-artery analysis, the assessment of coronary lumen by 64-slice MDCT compared with coronary IVUS showed a good overall diagnostic ability, regardless of the presence or absence of underlying atherosclerotic plaques.

  3. Comparison between MDCT and Grayscale IVUS in a Quantitative Analysis of Coronary Lumen in Segments with or without Atherosclerotic Plaques

    PubMed Central

    Falcão, João L. A. A.; Falcão, Breno A. A.; Gurudevan, Swaminatha V.; Campos, Carlos M.; Silva, Expedito R.; Kalil-Filho, Roberto; Rochitte, Carlos E.; Shiozaki, Afonso A.; Coelho-Filho, Otavio R.; Lemos, Pedro A.

    2015-01-01

    Background The diagnostic accuracy of 64-slice MDCT in comparison with IVUS has been poorly described and is mainly restricted to reports analyzing segments with documented atherosclerotic plaques. Objectives We compared 64-slice multidetector computed tomography (MDCT) with gray scale intravascular ultrasound (IVUS) for the evaluation of coronary lumen dimensions in the context of a comprehensive analysis, including segments with absent or mild disease. Methods The 64-slice MDCT was performed within 72 h before the IVUS imaging, which was obtained for at least one coronary, regardless of the presence of luminal stenosis at angiography. A total of 21 patients were included, with 70 imaged vessels (total length 114.6 ± 38.3 mm per patient). A coronary plaque was diagnosed in segments with plaque burden > 40%. Results At patient, vessel, and segment levels, average lumen area, minimal lumen area, and minimal lumen diameter were highly correlated between IVUS and 64-slice MDCT (p < 0.01). However, 64-slice MDCT tended to underestimate the lumen size with a relatively wide dispersion of the differences. The comparison between 64-slice MDCT and IVUS lumen measurements was not substantially affected by the presence or absence of an underlying plaque. In addition, 64-slice MDCT showed good global accuracy for the detection of IVUS parameters associated with flow-limiting lesions. Conclusions In a comprehensive, multi-territory, and whole-artery analysis, the assessment of coronary lumen by 64-slice MDCT compared with coronary IVUS showed a good overall diagnostic ability, regardless of the presence or absence of underlying atherosclerotic plaques. PMID:25993595

  4. Comparison between MDCT and Grayscale IVUS in a Quantitative Analysis of Coronary Lumen in Segments with or without Atherosclerotic Plaques.

    PubMed

    Falcão, João L A A; Falcão, Breno A A; Gurudevan, Swaminatha V; Campos, Carlos M; Silva, Expedito R; Kalil-Filho, Roberto; Rochitte, Carlos E; Shiozaki, Afonso A; Coelho-Filho, Otavio R; Lemos, Pedro A

    2015-04-01

    The diagnostic accuracy of 64-slice MDCT in comparison with IVUS has been poorly described and is mainly restricted to reports analyzing segments with documented atherosclerotic plaques. We compared 64-slice multidetector computed tomography (MDCT) with gray scale intravascular ultrasound (IVUS) for the evaluation of coronary lumen dimensions in the context of a comprehensive analysis, including segments with absent or mild disease. The 64-slice MDCT was performed within 72 h before the IVUS imaging, which was obtained for at least one coronary, regardless of the presence of luminal stenosis at angiography. A total of 21 patients were included, with 70 imaged vessels (total length 114.6 ± 38.3 mm per patient). A coronary plaque was diagnosed in segments with plaque burden > 40%. At patient, vessel, and segment levels, average lumen area, minimal lumen area, and minimal lumen diameter were highly correlated between IVUS and 64-slice MDCT (p < 0.01). However, 64-slice MDCT tended to underestimate the lumen size with a relatively wide dispersion of the differences. The comparison between 64-slice MDCT and IVUS lumen measurements was not substantially affected by the presence or absence of an underlying plaque. In addition, 64-slice MDCT showed good global accuracy for the detection of IVUS parameters associated with flow-limiting lesions. In a comprehensive, multi-territory, and whole-artery analysis, the assessment of coronary lumen by 64-slice MDCT compared with coronary IVUS showed a good overall diagnostic ability, regardless of the presence or absence of underlying atherosclerotic plaques.

  5. In the workup of patients with obscure gastrointestinal bleed, does 64-slice MDCT have a role?

    PubMed

    Kulkarni, Chinmay; Moorthy, Srikanth; Sreekumar, Kp; Rajeshkannan, R; Nazar, Pk; Sandya, Cj; Sivasubramanian, S; Ramchandran, Pv

    2012-01-01

    The purpose was to prospectively determine the sensitivity of 64-slice MDCT in detecting and diagnosing the cause of obscure gastrointestinal bleed (OGIB). Our study included 50 patients (male 30, female 20) in the age range of 3-82 years (average age: 58.52 years) who were referred to our radiology department as part of their workup for clinically evident gastrointestinal (GI) bleed or as part of workup for anemia (with and without positive fecal occult blood test). All patients underwent conventional upper endoscopy and colonoscopy before undergoing CT scan. Following a noncontrast scan, all patients underwent triple-phase contrast CT scan using a 64-slice CT scan system. The diagnostic performance of 64-slice MDCT was compared to the results of capsule endoscopy, 99m-technetium-labeled red blood cell scintigraphy (99mTc-RBC scintigraphy), digital subtraction angiography, and surgery whenever available. CT scan showed positive findings in 32 of 50 patients. The sensitivity, specificity, positive predictive value, and negative predictive values of MDCT for detection of bleed were 72.2%, 42.8%, 81.2%, and 44.4%, respectively. Capsule endoscopy was done in 15 patients and was positive in 10 patients; it had a sensitivity of 71.4%. Eleven patients had undergone 99mTc-RBC scintigraphy prior to CT scan, and the result was positive in seven patients (sensitivity 70%). Digital subtraction angiography was performed in only eight patients and among them all except one patient showed findings consistent with the lesions detected on MDCT. MDCT is a sensitive and noninvasive tool that allows rapid detection and localization of OGIB. It can be used as the first-line investigation in patients with negative endoscopy and colonoscopy studies. MDCT and capsule endoscopy have complementary roles in the evaluation of OGIB.

  6. Cardiac MDCT in children: CT technology overview and interpretation.

    PubMed

    Goo, Hyun Woo

    2011-09-01

    Cardiac multidetector computed tomography (MDCT) for congenital heart disease is a useful, rapid, and noninvasive imaging technique bridging the gaps between echocardiography, cardiac catheterization, and cardiac MRI. Fast scan speed and greater anatomic coverage, combined with flexible ECG-synchronized scans and a low radiation dose, are critical for improving the image quality of cardiac MDCT and minimizing patient risk. Current MDCT techniques can accurately evaluate extracardiac great vessels, lungs, and airways, as well as coronary arteries and intracardiac structures. Radiologists who perform cardiac MDCT in children should be familiarized with optimal cardiac computed tomography (CT) scan techniques and characteristic cardiac CT scan imaging findings. Copyright © 2011 Elsevier Inc. All rights reserved.

  7. Assessment of Gd-EOB-DTPA-enhanced MRI for HCC and dysplastic nodules and comparison of detection sensitivity versus MDCT.

    PubMed

    Inoue, Tatsuo; Kudo, Masatoshi; Komuta, Mina; Hayaishi, Sosuke; Ueda, Taisuke; Takita, Masahiro; Kitai, Satoshi; Hatanaka, Kinuyo; Yada, Norihisa; Hagiwara, Satoru; Chung, Hobyung; Sakurai, Toshiharu; Ueshima, Kazuomi; Sakamoto, Michiie; Maenishi, Osamu; Hyodo, Tomoko; Okada, Masahiro; Kumano, Seishi; Murakami, Takamichi

    2012-09-01

    We aimed to evaluate gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) for the detection of hepatocellular carcinomas (HCCs) and dysplastic nodules (DNs) compared with dynamic multi-detector row computed tomography (MDCT), and to discriminate between HCCs and DNs. Eighty-six nodules diagnosed as HCC or DNs were retrospectively investigated. Gd-EOB-DTPA-enhanced MRI and dynamic MDCT were compared with respect to their diagnostic ability for hypervascular HCCs and detection sensitivity for hypovascular tumors. The ability of hepatobiliary images of Gd-EOB-DTPA-enhanced MRI to discriminate between these nodules was assessed. We also calculated the EOB enhancement ratio of the tumors. For hypervascular HCCs, the diagnostic ability of Gd-EOB-DTPA-enhanced MRI was significantly higher than that of MDCT for tumors less than 2 cm (p = 0.048). There was no difference in the detection of hypervascular HCCs between hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI (43/45: 96%) and dynamic MDCT (40/45: 89%), whereas the detection sensitivity of hypovascular tumors by Gd-EOB-DTPA-enhanced MRI was significantly higher than that by dynamic MDCT (39/41: 95% vs. 25/41: 61%, p = 0.001). EOB enhancement ratios were decreased in parallel with the degree of differentiation in DNs and HCCs, although there was no difference between DNs and hypovascular well-differentiated HCCs. The diagnostic ability of Gd-EOB-DTPA-enhanced MRI for hypervascular HCCs less than 2 cm was significantly higher than that of MDCT. For hypovascular tumors, the detection sensitivity of hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI was significantly higher than that of dynamic Gd-EOB-DTPA-enhanced MRI and dynamic MDCT. It was difficult to distinguish between DNs and hypovascular well-differentiated HCCs based on the EOB enhancement ratio.

  8. Postmortem imaging: MDCT features of postmortem change and decomposition.

    PubMed

    Levy, Angela D; Harcke, Howard Theodore; Mallak, Craig T

    2010-03-01

    Multidetector computed tomography (MDCT) has emerged as an effective imaging technique to augment forensic autopsy. Postmortem change and decomposition are always present at autopsy and on postmortem MDCT because they begin to occur immediately upon death. Consequently, postmortem change and decomposition on postmortem MDCT should be recognized and not mistaken for a pathologic process or injury. Livor mortis increases the attenuation of vasculature and dependent tissues on MDCT. It may also produce a hematocrit effect with fluid levels in the large caliber blood vessels and cardiac chambers from dependent layering erythrocytes. Rigor mortis and algor mortis have no specific MDCT features. In contrast, decomposition through autolysis, putrefaction, and insect and animal predation produce dramatic alterations in the appearance of the body on MDCT. Autolysis alters the attenuation of organs. The most dramatic autolytic changes on MDCT are seen in the brain where cerebral sulci and ventricles are effaced and gray-white matter differentiation is lost almost immediately after death. Putrefaction produces a pattern of gas that begins with intravascular gas and proceeds to gaseous distension of all anatomic spaces, organs, and soft tissues. Knowledge of the spectrum of postmortem change and decomposition is an important component of postmortem MDCT interpretation.

  9. Comparing Two Approaches for Assessing Observation Impact

    NASA Technical Reports Server (NTRS)

    Todling, Ricardo

    2013-01-01

    Langland and Baker introduced an approach to assess the impact of observations on the forecasts. In that approach, a state-space aspect of the forecast is defined and a procedure is derived ultimately relating changes in the aspect with changes in the observing system. Some features of the state-space approach are to be noted: the typical choice of forecast aspect is rather subjective and leads to incomplete assessment of the observing system, it requires availability of a verification state that is in practice correlated with the forecast, and it involves the adjoint operator of the entire data assimilation system and is thus constrained by the validity of this operator. This article revisits the topic of observation impacts from the perspective of estimation theory. An observation-space metric is used to allow inferring observation impact on the forecasts without the limitations just mentioned. Using differences of observation-minus-forecast residuals obtained from consecutive forecasts leads to the following advantages: (i) it suggests a rather natural choice of forecast aspect that directly links to the data assimilation procedure, (ii) it avoids introducing undesirable correlations in the forecast aspect since verification is done against the observations, and (iii) it does not involve linearization and use of adjoints. The observation-space approach has the additional advantage of being nearly cost free and very simple to implement. In its simplest form it reduces to evaluating the statistics of observationminus- background and observation-minus-analysis residuals with traditional methods. Illustrations comparing the approaches are given using the NASA Goddard Earth Observing System.

  10. Hepatosplenic volumetric assessment at MDCT for staging liver fibrosis.

    PubMed

    Pickhardt, Perry J; Malecki, Kyle; Hunt, Oliver F; Beaumont, Claire; Kloke, John; Ziemlewicz, Timothy J; Lubner, Meghan G

    2017-07-01

    To investigate hepatosplenic volumetry at MDCT for non-invasive prediction of hepatic fibrosis. Hepatosplenic volume analysis in 624 patients (mean age, 48.8 years; 311 M/313 F) at MDCT was performed using dedicated software and compared against pathological fibrosis stage (F0 = 374; F1 = 48; F2 = 40; F3 = 65; F4 = 97). The liver segmental volume ratio (LSVR) was defined by Couinaud segments I-III over segments IV-VIII. All pre-cirrhotic fibrosis stages (METAVIR F1-F3) were based on liver biopsy within 1 year of MDCT. LSVR and total splenic volumes increased with stage of fibrosis, with mean(±SD) values of: F0: 0.26 ± 0.06 and 215.1 ± 88.5 mm(3); F1: 0.25 ± 0.08 and 294.8 ± 153.4 mm(3); F2: 0.331 ± 0.12 and 291.6 ± 197.1 mm(3); F3: 0.39 ± 0.15 and 509.6 ± 402.6 mm(3); F4: 0.56 ± 0.30 and 790.7 ± 450.3 mm(3), respectively. Total hepatic volumes showed poor discrimination (F0: 1674 ± 320 mm(3); F4: 1631 ± 691 mm(3)). For discriminating advanced fibrosis (≥F3), the ROC AUC values for LSVR, total liver volume, splenic volume and LSVR/spleen combined were 0.863, 0.506, 0.890 and 0.947, respectively. Relative changes in segmental liver volumes and total splenic volume allow for non-invasive staging of hepatic fibrosis, whereas total liver volume is a poor predictor. Unlike liver biopsy or elastography, these CT volumetric biomarkers can be obtained retrospectively on routine scans obtained for other indications. • Regional changes in hepatic volume (LSVR) correlate well with degree of fibrosis. • Total liver volume is a very poor predictor of underlying fibrosis. • Total splenic volume is associated with the degree of hepatic fibrosis. • Hepatosplenic volume assessment is comparable to elastography for staging fibrosis. • Unlike elastography, volumetric analysis can be performed retrospectively.

  11. Comparing Simulated and Observed Gross Primary Productivity

    NASA Astrophysics Data System (ADS)

    Schaefer, K.

    2009-12-01

    As part of the North American Carbon Program (NACP) Site-level Interim Synthesis, we compare simulated and observed Gross Primary Productivity (GPP) from 21 models at 36 eddy covariance flux towers. Evaluation of terrestrial carbon models typically include comparison of simulated and observed Net Ecosystem Exchange (NEE) at eddy covariance Flux towers, but such comparisons rarely include ecosystem respiration (Re) and GPP because they are not directly measured and must be estimated from observed NEE. All 21 models participating in the NACP Site-Level Interim Synthesis ran simulations at each tower using a standard simulation protocol with gap-filled observed weather. The observed NEE at all 36 towers are partitioned into Re and GPP using a standard procedure. The gap-filled observed NEE, Re, and GPP include estimated uncertainties at multiple time scales due to random variability, gap-filling technique, friction velocity filtering, and flux partitioning. We quantify each model’s performance in reproducing the estimated GPP using uncertainty weighted cost functions, root-mean-square error (bias), correlations, and Taylor diagrams at the diurnal, seasonal, and annual time scales. We relate model performance to model characteristics, such as the type of photosynthesis model (light use efficiency vs. stomatal conductance), phenology (diagnostic vs. prognostic), values of common parameters, and representation of the physical environment (soil temperature, soil moisture, and vapor pressure deficit).

  12. MDCT Versus MRI Assessment of Tumor Response After Transarterial Chemoembolization for the Treatment of Hepatocellular Carcinoma

    SciTech Connect

    Kloeckner, Roman; Otto, Gerd; Biesterfeld, Stefan; Oberholzer, Katja; Dueber, Christoph; Pitton, Michael B.

    2010-06-15

    The purpose of this study was to compare the ability of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) to evaluate treatment results after transarterial chemoembolization (TACE), with a special focus on the influence of Lipiodol on calculation of tumor necrosis according to EASL criteria. A total of 115 nodules in 20 patients (17 males, 3 females; 69.5 {+-} 9.35 years) with biopsy-proven hepatocellular carcinoma were treated with TACE. Embolization was performed using a doxorubicin-Lipiodol emulsion (group I) or DC Beads loaded with doxorubicin (group II). Follow-up included triphasic contrast-enhanced 64-row MDCT (collimation, 0.625 mm; slice, 3 mm; contrast bolus, 120 ml iomeprol; delay by bolus trigger) and contrast-enhanced MRI (T1 native, T2 native; five dynamic contrast-enhanced phases; 0.1 mmol/kg body weight gadolinium-DTPA; slice thickness, 4 mm). Residual tumor and the extent of tumor necrosis were evaluated according to EASL. Contrast enhancement within tumor lesions was suspected to represent vital tumor. In the Lipiodol-based TACE protocol, MDCT underestimated residual viable tumor compared to MRI, due to Lipiodol artifacts (23.2% vs 47.7% after first, 11.9% vs 31.2% after second, and 11.4% vs 23.7% after third TACE; p = 0.0014, p < 0.001, and p < 0.001, respectively). In contrast to MDCT, MRI was completely free of any artifacts caused by Lipiodol. In the DC Bead-based Lipiodol-free TACE protocol, MRI and CT showed similar residual tumor and rating of treatment results (46.4% vs 41.2%, 31.9 vs 26.8%, and 26.0% vs 25.6%; n.s.). In conclusion, MRI is superior to MDCT for detection of viable tumor residuals after Lipiodol-based TACE. Since viable tumor tissue is superimposed by Lipiodol artifacts in MDCT, MRI is mandatory for reliable decision-making during follow-up after Lipiodol-based TACE protocols.

  13. Dose reduction in paediatric MDCT: general principles.

    PubMed

    Paterson, A; Frush, D P

    2007-06-01

    The number of multi-detector array computed tomography (MDCT) examinations performed per annum continues to increase in both the adult and paediatric populations. Estimates from 2003 suggested that CT contributed 17% of a radiology department's workload, yet was responsible for up to 75% of the collective population dose from medical radiation. The effective doses for some CT examinations today overlap with those argued to have an increased risk of cancer. This is especially pertinent for paediatric CT, as children are more radiosensitive than adults (and girls more radiosensitive than boys). In addition, children have a longer life ahead of them, in which radiation induced cancers may become manifest. Radiologists must be aware of these facts and practise the ALARA (as low as is reasonably achievable) principle, when it comes to deciding CT protocols and parameters.

  14. MDCT of acute thrombotic and nonthrombotic pulmonary emboli.

    PubMed

    Bhalla, Sanjeev; Lopez-Costa, Ignacio

    2007-10-01

    Acute pulmonary embolism (PE) remains a common clinical challenge. MDCT pulmonary angiography has become the first line imaging study in the diagnosis of PE because of its speed, accuracy, low-interobserver variability, and ability to provide alternative diagnoses. This review article highlights the role of MDCT in the evaluation of acute thrombotic PE in the era of PIOPED 2. MDCT findings of acute PE and some potential pitfalls are covered as well as some of the controversies in imaging young and pregnant patients. MDCT findings of acute non-thrombotic PE are also covered. This latter group may be occult on the angiographic portion of the study but may declare themselves through secondary findings. Their findings and potential mimics are included so that the interpreting radiologist can make the most of a CT to rule out PE.

  15. Risk of contrast-medium-induced nephropathy in high-risk patients undergoing MDCT--a pooled analysis of two randomized trials.

    PubMed

    Thomsen, Henrik S; Morcos, Sameh K

    2009-04-01

    The incidence of contrast-medium-induced nephropathy (CIN) following intravenous (IV) CM administration of contrast media to renally impaired patients undergoing multidetector computed tomography (MDCT) is not well characterized. Our objective was to investigate the incidence of CIN in patients with glomerular filtration rate (GFR) <60 ml/min undergoing contrast-enhanced MDCT examinations and to compare the rates of CIN following the IV administration of low-osmolar contrast media (LOCM, iopamidol and iomeprol) and an iso-osmolar contrast medium (IOCM, iodixanol). A total of 301 adult patients with moderate-to-severe renal failure received a similar IV contrast dose (40 gI). Serum creatinine (SCr) was measured at screening, baseline and 48-72 +/- 6 h after the MDCT examination. Primary CIN outcome was an increase in SCr >or=0.5 mg/dl (>or=44.2 micromol/l) from baseline. The CIN rates were 2.3% in the total population, 0.6% when GFR >40 ml/min, 4.6% when GFR <40 ml/min and 7.8% in patients with GFR <30 ml/min. The incidence of CIN was significantly higher after iodixanol than after LOCM (seven patients, 4.7% following IOCM, no CIN cases following the LOCM; p = 0.007). Significant differences in favor of the LOCM were also observed in patients with GFR <40 ml/min and GFR <30 ml/min. Following the IV administration of nonionic contrast agents in patients with moderate-to-severe renal insufficiency, the risk of significant CIN seems to be low. The IOCM iodixanol caused a higher rate of CIN than the LOCM iopamidol and iomeprol, especially in high-risk patients. Differences in osmolality between these LOCM and iodixanol do not play a role in the genesis of CIN.

  16. Conventional and reduced radiation dose of 16-MDCT for detection of nephrolithiasis and ureterolithiasis.

    PubMed

    Paulson, Erik K; Weaver, Carolyn; Ho, Lisa M; Martin, Lucie; Li, Jianying; Darsie, James; Frush, Donald P

    2008-01-01

    Our purpose was to prospectively compare the reader compatibility and acceptability of a range of reduced-dose 16-MDCT images with standard-dose 16-MDCT images for the detection of nephroureterolithiasis using a dose reduction simulation technique. The study was HIPAA compliant and institutional review board approved. Fifty consecutive patients with suspected nephrolithiasis were recruited to undergo conventional renal stone unenhanced 16-MDCT with at least 160 mA. Noise was then artificially introduced to simulate levels of 70, 100, and 130 mA. Three blinded independent readers interpreted the original and simulated-dose scans for the location and number of renal and ureteral calculi and secondary signs of obstruction using a 5-point confidence scale. Reader acceptability of scans was inversely related to noise. There was no significant reduction in readers' confidence in detection or exclusion of renal collecting system calculi with simulated reduction of mA of 70, 100, and 130 compared with the standard-dose study. However, for ureteral calcifications, there was a decrease in confidence for the detection or exclusion of ureterolithiasis at an mA of 70 (35 mAs). An mA as low as 70 (35 mAs) is acceptable for evaluation of nephrolithiasis. However, the evaluation of ureterolithiasis is compromised with an mA of 70.

  17. Spontaneous Renal Artery Dissection as a Cause of Acute Renal Infarction: Clinical and MDCT Findings.

    PubMed

    Yoon, Kibo; Song, Soon Young; Lee, Chang Hwa; Ko, Byung Hee; Lee, Seunghun; Kang, Bo Kyeong; Kim, Mi Mi

    2017-04-01

    The purpose of this study was to assess the incidence of spontaneous renal artery dissection (SRAD) as a cause of acute renal infarction, and to evaluate the clinical and multidetector computed tomography (MDCT) findings of SRAD. From November 2011 to January 2014, 35 patients who were diagnosed with acute renal infarction by MDCT were included. We analyzed the 35 MDCT data sets and medical records retrospectively, and compared clinical and imaging features of SRAD with an embolism, using Fisher's exact test and the Mann-Whitney test. The most common cause of acute renal infarction was an embolism, and SRAD was the second most common cause. SRAD patients had new-onset hypertension more frequently than embolic patients. Embolic patients were found to have increased C-reactive protein (CRP) more often than SRAD patients. Laboratory results, including tests for lactate dehydrogenase (LDH) and blood urea nitrogen (BUN), and the BUN/creatinine ratio (BCR) were significantly higher in embolic patients than SRAD patients. Bilateral renal involvement was detected in embolic patients more often than in SRAD patients. MDCT images of SRAD patients showed the stenosis of the true lumen, due to compression by a thrombosed false lumen. None of SRAD patients progressed to an estimated glomerular filtration rate < 60 mL/min/1.73 m² or to end-stage renal disease during the follow-up period. SRAD is not a rare cause of acute renal infarction, and it has a benign clinical course. It should be considered in a differential diagnosis of acute renal infarction, particularly in patients with new-onset hypertension, unilateral renal involvement, and normal ranges of CRP, LDH, BUN, and BCR.

  18. Spontaneous Renal Artery Dissection as a Cause of Acute Renal Infarction: Clinical and MDCT Findings

    PubMed Central

    2017-01-01

    The purpose of this study was to assess the incidence of spontaneous renal artery dissection (SRAD) as a cause of acute renal infarction, and to evaluate the clinical and multidetector computed tomography (MDCT) findings of SRAD. From November 2011 to January 2014, 35 patients who were diagnosed with acute renal infarction by MDCT were included. We analyzed the 35 MDCT data sets and medical records retrospectively, and compared clinical and imaging features of SRAD with an embolism, using Fisher's exact test and the Mann-Whitney test. The most common cause of acute renal infarction was an embolism, and SRAD was the second most common cause. SRAD patients had new-onset hypertension more frequently than embolic patients. Embolic patients were found to have increased C-reactive protein (CRP) more often than SRAD patients. Laboratory results, including tests for lactate dehydrogenase (LDH) and blood urea nitrogen (BUN), and the BUN/creatinine ratio (BCR) were significantly higher in embolic patients than SRAD patients. Bilateral renal involvement was detected in embolic patients more often than in SRAD patients. MDCT images of SRAD patients showed the stenosis of the true lumen, due to compression by a thrombosed false lumen. None of SRAD patients progressed to an estimated glomerular filtration rate < 60 mL/min/1.73 m2 or to end-stage renal disease during the follow-up period. SRAD is not a rare cause of acute renal infarction, and it has a benign clinical course. It should be considered in a differential diagnosis of acute renal infarction, particularly in patients with new-onset hypertension, unilateral renal involvement, and normal ranges of CRP, LDH, BUN, and BCR. PMID:28244286

  19. Managing patient dose in multi-detector computed tomography(MDCT). ICRP Publication 102.

    PubMed

    Valentin, J

    2007-01-01

    Computed tomography (CT) technology has changed considerably in recent years with the introduction of increasing numbers of multiple detector arrays. There are several parameters specific to multi-detector computed tomography (MDCT) scanners that increase or decrease patient dose systematically compared to older single detector computed tomography (SDCT) scanners. This document briefly reviews the MDCT technology, radiation dose in MDCT, including differences from SDCT and factors that affect dose, radiation risks, and the responsibilities for patient dose management. The document recommends that users need to understand the relationship between patient dose and image quality and be aware that image quality in CT is often higher than that necessary for diagnostic confidence. Automatic exposure control (AEC) does not totally free the operator from selection of scan parameters, and awareness of individual systems is important. Scanning protocols cannot simply be transferred between scanners from different manufacturers and should be determined for each MDCT. If the image quality is appropriately specified by the user, and suited to the clinical task, there will be a reduction in patient dose for most patients. Understanding of some parameters is not intuitive and the selection of image quality parameter values in AEC systems is not straightforward. Examples of some clinical situation shave been included to demonstrate dose management, e.g. CT examinations of the chest, the heart for coronary calcium quantification and non-invasive coronary angiography, colonography, the urinary tract, children, pregnant patients, trauma cases, and CT guided interventions. CT is increasingly being used to replace conventional x-ray studies and it is important that patient dose is given careful consideration, particularly with repeated or multiple examinations.

  20. 3D Volumetric Evaluation of Lipiodol Retention in HCC after Chemoembolization: A Quantitative Comparison between CBCT and MDCT

    PubMed Central

    Wang, Zhijun; Lin, MingDe; Lesage, David; Chen, Rongxin; Chapiro, Julius; Gu, Tara; Tacher, Vania; Duran, Rafael; Geschwind, Jean-François

    2014-01-01

    Rationale and Objectives To evaluate the capability of cone-beam computed tomography (CBCT) acquired immediately after transcatheter arterial chemoembolization (TACE) in determining Lipiodol retention quantitatively and volumetrically when compared to 1-day post-procedure unenhanced MDCT. Materials and methods From June to December, 2012, fifteen patients met the inclusion criteria of unresectable hepatocellular carcinoma (HCC) that was treated with conventional TACE (cTACE), and had intra-procedural CBCT and 1-day post-TACE MDCT. Four patients were excluded because the Lipiodol was diffuse throughout the entire liver or Lipiodol deposition was not clear on both CBCT and MDCT. Eleven patients with a total of 31 target lesions were included in the analysis. A quantitative and 3D software was used to assess complete, localized and diffuse lipiodol deposition. Tumor volume, Lipiodol volume in the tumor, % Lipiodol retention, and Lipiodol enhancement in Hounsfield Unit (HU) were calculated and compared between CBCT and MDCT using two-tailed student’s t-test and Bland-Altman plots. Results The mean value of tumor volume, Lipiodol deposited regions, calculated average % Lipiodol retention, and HU value of CBCT were not significantly different from those of MDCT (tumor volume: 9.37±11.35cm3 vs. 9.34±11.44cm3, P=0.991; Lipiodol volume: 7.84±9.34cm3 vs. 7.84±9.60 cm3, P=0.998; % Lipiodol retention: 89.3%±14.7% vs. 90.2% ± 14.9%, P=0.811; HU value: 307.7±160.1 HU vs. 257.2±120.0 HU, P=0.139). Bland-Altman plots showed only minimal difference and high agreement when comparing CBCT to MDCT. Conclusion CBCT has a similar capability, intraprocedurally, to assess Lipiodol deposition in 3D for patients with HCC treated with cTACE when compared to MDCT. PMID:24507426

  1. Roles of Naturalistic Observation in Comparative Psychology

    ERIC Educational Resources Information Center

    Miller, David B.

    1977-01-01

    "Five roles are considered by which systematic, quantified field research can augment controlled laboratory experimentation in terms of increasing the validity of laboratory studies." Advocates that comparative psychologists should "take more initiative in designing, executing, and interpreting our experiments with regard to the natural history of…

  2. Roles of Naturalistic Observation in Comparative Psychology

    ERIC Educational Resources Information Center

    Miller, David B.

    1977-01-01

    "Five roles are considered by which systematic, quantified field research can augment controlled laboratory experimentation in terms of increasing the validity of laboratory studies." Advocates that comparative psychologists should "take more initiative in designing, executing, and interpreting our experiments with regard to the natural history of…

  3. Validation of cone-beam computed tomography and magnetic resonance imaging of the porcine spine: a comparative study with multidetector computed tomography and anatomical specimens.

    PubMed

    de Freitas, Ricardo Miguel Costa; Andrade, Celi Santos; Caldas, José Guilherme Mendes Pereira; Kanas, Alexandre Fligelman; Cabral, Richard Halti; Tsunemi, Miriam Harumi; Rodríguez, Hernán Joel Cervantes; Rabbani, Said Rahnamaye

    2015-05-01

    New spinal interventions or implants have been tested on ex vivo or in vivo porcine spines, as they are readily available and have been accepted as a comparable model to human cadaver spines. Imaging-guided interventional procedures of the spine are mostly based on fluoroscopy or, still, on multidetector computed tomography (MDCT). Cone-beam computed tomography (CBCT) and magnetic resonance imaging (MRI) are also available methods to guide interventional procedures. Although some MDCT data from porcine spines are available in the literature, validation of the measurements on CBCT and MRI is lacking. To describe and compare the anatomical measurements accomplished with MDCT, CBCT, and MRI of lumbar porcine spines to determine if CBCT and MRI are also useful methods for experimental studies. An experimental descriptive-comparative study. Sixteen anatomical measurements of an individual vertebra from six lumbar porcine spines (n=36 vertebrae) were compared with their MDCT, CBCT, and MRI equivalents. Comparisons were made for the absolute values of the parameters. Similarities were found in all imaging methods. Significant correlation (p<.05) was observed with all variables except those that included cartilaginous tissue from the end plates when the anatomical study was compared with the imaging methods. The CBCT and MRI provided imaging measurements of the lumbar porcine spines that were similar to the anatomical and MDCT data, and they can be useful for specific experimental research studies. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. [MDCT features and anatomic-pathological basis of the diseases in central thoracic-abdominal junctional region].

    PubMed

    Ye, Yilan; Yang, Zhigang; Li, Hua; Deng, Wen; Li, Yuan; Guo, Yingkun

    2012-02-01

    This paper is to determine relationship between MDCT features and anatomic-pathology of the diseases in central thoracic-abdominal junctional region. 3 cadavers were cut transversely and another 3 vertically to observe the anatomy of thoracic-abdominal junctional zone. 93 patients with diseases in central thoracic-abdominal junctional zone were scanned with MDCT. The correlation between MDCT features of the diseases in central thoracic-abdominal junctional region and the anatomic-pathology of the diseases in this region was evaluated. On cadaver sections, central thoracic-abdominal junctional region was an area between anterior chest wall and dorsal spine in vertical direction. The region was separated into upper and lower sections by diaphragm. The upper section mainly contains heart and pericardium, while the lower contains broad ligament and left lobe of liver. The hiatus of diaphragm are vena caval foramen, esophageal foramen and aortic foramen in anterior-posterior turn. In the present study, 23 patients had portal hypertension, 18 had dissection of aorta, 8 got diseases in inferior vena cava, 9 had lymphoma, 12 got diseases in multiple vertebrae, 7 had lower thoracic esophageal carcinoma accompanied with metastasis in upper abdominal lymph nodes, 9 had carcinoma of abdominal esophagus and/or gastric cardia, 4 had esophageal hiatal hernia and 3 patients had neurogenic tumor in posterior mediastinum and/or superior spatium retroperitoneale. The MDCT features and distribution of the diseases in central thoracic-abdominal junctional region influence the anatomic-pathology characteristics in this region.

  5. Quantification of arterial plaque and lumen density with MDCT

    SciTech Connect

    Paul, Narinder S.; Blobel, Joerg; Kashani, Hany; Rice, Murray; Ursani, Ali

    2010-08-15

    Purpose: This study aimed to derive a mathematical correction function in order to normalize the CT number measurements for small volume arterial plaque and small vessel mimicking objects, imaged with multidetector CT (MDCT). Methods: A commercially available calcium plaque phantom (QRM GmbH, Moehrendorf, Germany) and a custom built cardiovascular phantom were scanned with 320 and 64 MDCT scanners. The calcium hydroxyapatite plaque phantom contained objects 0.5-5.0 mm in diameter with known CT attenuation nominal values ranging 50-800 HU. The cardiovascular phantom contained vessel mimicking objects 1.0-5.0 mm in diameter with different contrast media. Both phantoms were scanned using clinical protocols for CT angiography and images were reconstructed with different filter kernels. The measured CT number (HU) and diameter of each object were analyzed on three clinical postprocessing workstations. From the resultant data, a mathematical formula was derived based on absorption function exp(-{mu}{sup *}d) to demonstrate the relation between measured CT numbers and object diameters. Results: The percentage reduction in measured CT number (HU) for the group of selected filter kernels, apparent during CT angiography, is dependent only on the object size (plaque or vessel diameter). The derived formula of the form 1-c{sup *}exp(-a{sup *}d{sup b}) showed reduction in CT number for objects between 0.5 and 5 mm in diameter, with asymptote reaching background noise for small objects with diameters nearing the CT in-plane resolution (0.35 mm). No reduction was observed for the objects with diameters equal or larger than 5 mm. Conclusions: A clear mathematical relationship exists between object diameter and reduction in measured CT number in HU. This function is independent of exposure parameters and inherent attenuation properties of the objects studied. Future developments include the incorporation of this mathematical model function into quantification software in order to

  6. MDCT evaluation of potential living renal donor, prior to laparoscopic donor nephrectomy: What the transplant surgeon wants to know?

    PubMed

    Ghonge, Nitin P; Gadanayak, Satyabrat; Rajakumari, Vijaya

    2014-10-01

    As Laparoscopic Donor Nephrectomy (LDN) offers several advantages for the donor such as lesser post-operative pain, fewer cosmetic concerns and faster recovery time, there is growing global trend towards LDN as compared to open nephrectomy. Comprehensive pre-LDN donor evaluation includes assessment of renal morphology including pelvi-calyceal and vascular system. Apart from donor selection, evaluation of the regional anatomy allows precise surgical planning. Due to limited visualization during laparoscopic renal harvesting, detailed pre-transplant evaluation of regional anatomy, including the renal venous anatomy is of utmost importance. MDCT is the modality of choice for pre-LDN evaluation of potential renal donors. Apart from appropriate scan protocol and post-processing methods, detailed understanding of surgical techniques is essential for the Radiologist for accurate image interpretation during pre-LDN MDCT evaluation of potential renal donors. This review article describes MDCT evaluation of potential living renal donor, prior to LDN with emphasis on scan protocol, post-processing methods and image interpretation. The article laid special emphasis on surgical perspectives of pre-LDN MDCT evaluation and addresses important points which transplant surgeons want to know.

  7. Coronary image quality of 320-MDCT in patients with heart rates above 65 beats per minute: preliminary experience.

    PubMed

    Lee, Allan B; Nandurkar, Dee; Schneider-Kolsky, Michal E; Crossett, Marcus; Seneviratne, Sujith K; Cameron, James D; Troupis, John M

    2011-06-01

    High heart rate may negatively influence the image quality of cardiac CT. The technical advances of 320-MDCT may overcome issues with poor image quality associated with high heart rate. This study aimed to evaluate the coronary image quality of 320-MDCT in patients with heart rates above 65 beats/min. Patients who presented for cardiac CT were divided into two groups according to heart rate, either greater than 65 beats/min or less than or equal to 65 beats/min. Two radiologists were blinded to the patient groups and evaluated images of 15 coronary artery segments per patient using 320-MDCT with consensus agreement. The image quality was scored subjectively as 1 or 2 (diagnostic quality) or 3 (poor quality and nondiagnostic). There were no statistically significant differences between the two groups in terms of age, sex, and body mass index (p > 0.05). The median heart rate was 70 beats/min (range, 67-110 beats/min) for the group with heart rate greater than 65 beats/min and 60 beats/min (range, 48-65 beats/min) for the group with heart rate less than or equal to 65 beats/min (p < 0.001). In patients with heart rates greater than 65 beats/min, diagnostic quality images (scores of 1 or 2) were obtained in 95.6% of the analyzed segments, compared with 96.9% in the group with heart rate less than or equal to 65 beats/min (p = 0.7). Our initial evaluation suggests that coronary artery images of diagnostic quality can be obtained using 320-MDCT in most patients with heart rates greater than 65 beats/min, in percentages similar to those for patients with heart rates less than or equal to 65 beats/min. This finding may be the result of the inherent image acquisition and reconstruction technique of 320-MDCT.

  8. Temporal resolution improvement using PICCS in MDCT cardiac imaging

    PubMed Central

    Chen, Guang-Hong; Tang, Jie; Hsieh, Jiang

    2009-01-01

    The current paradigm for temporal resolution improvement is to add more source-detector units and∕or increase the gantry rotation speed. The purpose of this article is to present an innovative alternative method to potentially improve temporal resolution by approximately a factor of 2 for all MDCT scanners without requiring hardware modification. The central enabling technology is a most recently developed image reconstruction method: Prior image constrained compressed sensing (PICCS). Using the method, cardiac CT images can be accurately reconstructed using the projection data acquired in an angular range of about 120°, which is roughly 50% of the standard short-scan angular range (∼240° for an MDCT scanner). As a result, the temporal resolution of MDCT cardiac imaging can be universally improved by approximately a factor of 2. In order to validate the proposed method, two in vivo animal experiments were conducted using a state-of-the-art 64-slice CT scanner (GE Healthcare, Waukesha, WI) at different gantry rotation times and different heart rates. One animal was scanned at heart rate of 83 beats per minute (bpm) using 400 ms gantry rotation time and the second animal was scanned at 94 bpm using 350 ms gantry rotation time, respectively. Cardiac coronary CT imaging can be successfully performed at high heart rates using a single-source MDCT scanner and projection data from a single heart beat with gantry rotation times of 400 and 350 ms. Using the proposed PICCS method, the temporal resolution of cardiac CT imaging can be effectively improved by approximately a factor of 2 without modifying any scanner hardware. This potentially provides a new method for single-source MDCT scanners to achieve reliable coronary CT imaging for patients at higher heart rates than the current heart rate limit of 70 bpm without using the well-known multisegment FBP reconstruction algorithm. This method also enables dual-source MDCT scanner to achieve higher temporal resolution

  9. Comparative Effectiveness Research Using Observational Data: Active Comparators to Emulate Target Trials with Inactive Comparators

    PubMed Central

    Huitfeldt, Anders; Hernan, Miguel A.; Kalager, Mette; Robins, James M.

    2016-01-01

    Introduction: Because a comparison of noninitiators and initiators of treatment may be hopelessly confounded, guidelines for the conduct of observational research often recommend using an “active” comparator group consisting of people who initiate a treatment other than the medication of interest. In this paper, we discuss the conditions under which this approach is valid if the goal is to emulate a trial with an inactive comparator. Identification of Effects: We provide conditions under which a target trial in a subpopulation can be validly emulated from observational data, using an active comparator that is known or believed to be inactive for the outcome of interest. The average treatment effect in the population as a whole is not identified, but under certain conditions this approach can be used to emulate a trial in the subset of individuals who were treated with the treatment of interest, in the subset of individuals who were treated with the treatment of interest but not with the comparator, or in the subset of individuals who were treated with both the treatment of interest and the active comparator. The Plausibility of the Comparability Conditions: We discuss whether the required conditions can be expected to hold in pharmacoepidemiologic research, with a particular focus on whether the conditions are plausible in situations where the standard analysis fails due to unmeasured confounding by access to health care or health seeking behaviors. Discussion: The conditions discussed in this paper may at best be approximately true. Investigators using active comparator designs to emulate trials with inactive comparators should exercise caution. PMID:27891526

  10. Feasibility of Free-breathing CCTA using 256-MDCT.

    PubMed

    Liu, Zhuo; Sun, Ye; Zhang, Zhuolu; Chen, Lei; Hong, Nan

    2016-07-01

    Usually, coronary computed tomography angiography (CCTA) is performed during breath-holding to reduce artifact caused by respiration. The objective of this study was to evaluate the feasibility of free-breathing CCTA compared to breath-holding using CT scanner with wide detector. To evaluate the feasibility of CCTA during free-breathing using a 256-MDCT. In 80 patients who underwent CCTA, 40 were performed during breath-holding (group A), and the remaining 40 during free-breathing (group B). The quality scores for coronary arteries were analyzed and defined as: 3 (excellent), 2 (good), and 1 (poor). The image noise, signal-to-noise ratio and effective radiation dose as well as the heart rate variation were compared. The noise, signal-to-noise ratio, and effective radiation dose were not significantly different between the 2 groups. The mean heart rate variation between planning and scanning for group A was 7 ± 7.6 bpm, and larger than 3 ± 2.6 bpm for group B (P = 0.012). Quality scores of the free-breathing group were better than those of the breath-holding group (group A: 2.55 ± 0.64, group B: 2.85 ± 0.36, P = 0.018). Free-breathing CCTA is feasible on wide detector CT scanner to provide acceptable image quality with reduced heart rate variation and better images for certain patients.

  11. Trauma whole-body MDCT: an assessment of image quality in conventional dual-phase and modified biphasic injection.

    PubMed

    Hakim, Wasim; Kamanahalli, Raghavendra; Dick, Elizabeth; Bharwani, Nishat; Fetherston, Shirley; Kashef, Elika

    2016-07-01

    To compare the image quality of conventional arterial and portal venous (PV) phase multidetector CT (MDCT) with two biphasic injection protocols in polytrauma patients. 60 consecutive patients with polytrauma underwent body 256-slice MDCT with a conventional protocol or 1 of 2 single-pass biphasic protocols: Group A, arterial (30 s) and PV (60 s) phase acquisitions; Group B, "biphasic" contrast injection with a single acquisition at 60 s; and Group C, "modified biphasic" injection with a single acquisition at a 70-s delay. Images were analyzed for arterial, venous and parenchymal attenuation profiles with regions of interest in the major arteries, veins and solid abdominal organs. A 5-point scoring system was used to assess the image quality, with 5 representing excellent arterial, venous and parenchymal opacification and <3 representing non-diagnostic opacification. In addition, the effective dose (millisieverts) was compared between the groups. In 93% of patients, image quality was scored as good or excellent (≥4). All studies were of satisfactory diagnostic quality. Overall, venous and arterial attenuation profiles were comparable. Attenuation profiles in the solid abdominal viscera were significantly higher (p < 0.01) using both biphasic protocols than with arterial or PV phase of conventional protocols. Effective doses were higher in Group A. Comparable image quality can be achieved using a biphasic i.v. contrast injection protocol with single MDCT acquisition with less radiation and reduction in acquisition time. For these particular biphasic injection protocols, we have shown that image quality is comparable with a conventional protocol. This has been achieved by comparing enhanced densities of specific structures, as well as gestalt scoring by assessors, on a 256-slice MDCT.

  12. Clear Cell Renal Cell Carcinoma: Identifying the Loss of the Y Chromosome on Multiphasic MDCT.

    PubMed

    Young, Jonathan R; Coy, Heidi; Douek, Michael; Lo, Pechin; Sayre, James; Pantuck, Allan J; Raman, Steven S

    2017-08-01

    The objective of our study was to investigate whether multiphasic MDCT enhancement can help identify clear cell renal cell carcinomas (RCCs) with the loss of the Y chromosome. We derived a cohort of 43 clear cell RCCs in men who underwent preoperative four-phase renal mass MDCT from October 2000 to August 2013. Each lesion was segmented in its entirety on axial images. A computer-assisted detection algorithm selected a 0.5-cm-diameter region of maximal attenuation within each lesion in each phase. A 0.5-cm-diameter ROI was manually placed on uninvolved renal cortex in each phase. The relative attenuation of each lesion was calculated as follows: [(maximal lesion attenuation - cortex attenuation) / cortex attenuation] × 100. Absolute attenuation and relative attenuation in each phase were compared using t tests. Both clear cell RCCs with the loss of the Y chromosome and clear cell RCCs without the loss of the Y chromosome exhibited peak enhancement in the corticomedullary phase. However, relative nephrographic attenuation of clear cell RCCs with the loss of Y was significantly less than that of clear cell RCCs without the loss of Y (mean, -8.9 vs 8.4 respectively; p = 0.013). A relative nephrographic attenuation threshold of -1.6 identified the loss of Y with an accuracy of 70% (30/43), sensitivity of 73% (16/22), and specificity of 67% (14/21). Multiphasic MDCT enhancement may assist in identifying the loss of the Y chromosome in clear cell RCCs; this result should be validated in a large prospective trial.

  13. Multidetector CT (MD-CT) in the diagnosis of uncertain open globe injuries.

    PubMed

    Hoffstetter, P; Schreyer, A G; Schreyer, C I; Jung, E M; Heiss, P; Zorger, N; Framme, C

    2010-02-01

    To evaluate the significance of multislice CT for the diagnosis of uncertain penetrating globe injuries. Based on a retrospective chart review between 2002 and 2007, we identified 59 patients presenting with severe ocular trauma with uncertain rupture of the globe due to massive subconjunctival and/or anterior chamber hemorrhage. The IOP (intraocular pressure) was within normal range in all patients. High resolution multidetector CT (MD-CT) scans (16 slice scans) with axial and coronar reconstructions were performed in all patients. The affected eye was examined for signs of penetrating injury such as abnormal eye shape, scleral irregularities, lens dislocation or intravitreal hemorrhages. Four experienced radiologists read the CT scans independently. Beside the diagnosis, the relevant morphological criteria and the optimal plane orientation (axial or coronar) were specified. The sensitivity, specificity, and negative and positive predictive value were calculated. Additionally the interobserver variability was determined by applying the Cohen's kappa test. Surgical sclera inspections were performed in all cases as a standard of reference. The evaluations of the CT examination were compared with the surgery reports. 59 patients were evaluated (42 men, 17 women). The mean age was 29 years (range 7 - 91). In 17 patients a rupture of the globe was diagnosed during surgery. 12 of these 17 penetrating injuries (70.6 %) were classified correctly by MDCT, 5 of the 17 (29.4 %) were not detectable. 42 patients did not have an open globe injury. 41 of these patients were diagnosed correctly negative by MDCT, and one patient was classified false positive. This results in a sensitivity of 70 % with a specificity of 98 %. There was high inter-rater agreement with kappa values between 0.89 - 0.96. Most discrepancies were caused by wrong negative findings. The most frequent morphologic criteria for open globe injury were the deformation (n = 10) and the volume reduction (n = 7) of

  14. Silicosis due to Denim Sandblasting in Young People: MDCT Findings.

    PubMed

    Doganay, Selim; Gocmen, Hayrettin; Yikilmaz, Ali; Coskun, Abdulhakim

    2010-04-01

    Occupational lung disease due to silica dust is one of the most common work-related injuries. In denim sandblasting, workers are exposed to silica that may cause immediate mortality, especially in young people. The aim of this study was to assess the multidetector computed tomography (MDCT) findings of silicosis in denim sandblasters and to better define the role of MDCT in the early detection of silicosis. The study included 12 consecutive male patients who were admitted to a pulmonary outpatient clinic between April 2009 and December 2009. All patients had been working as sandblasters for at least one year. All patients underwent chest CT examinations for suspected silicosis. Two radiologists independently assessed the images for the presence and distribution of airspace consolidation, ground-glass opacity, nodules, interlobular septal thickening, parenchymal bands, fibrosis, masses, traction bronchiectasis, honeycombing, lobular low-attenuation areas, emphysema, pleural effusion or thickening, and mediastinal or hilar adenopathy. MDCT detected parenchymal abnormalities in the lungs in eight (67%) of the twelve patients. The most common MDCT finding was ground glass opacity (58%). Other common findings were parencyhmal nodules and interlobular septal thickening, predominantly in the upper zones. Nodules were detected in six (50%) of the twelve patients. In four cases (67%), the nodules were numerous (>10), were predominantly smaller than 10 mm, and were centrilobular in distribution. In five (42%) of the 12 patients, interlobular septal thickening was detected. Only one (8%) patient presented with airspace consolidation; this was bilateral in the upper zones and associated with air bronchograms. In one (8%) patient there were several traction bronchiectases in the upper zones. None of the patients presented with pleural effusion, thickening, or honeycombing. Enlarged mediastinal nodes were identified in half of the patients, predominantly in the precarinal

  15. Silicosis due to Denim Sandblasting in Young People: MDCT Findings

    PubMed Central

    Doganay, Selim; Gocmen, Hayrettin; Yikilmaz, Ali; Coskun, Abdulhakim

    2010-01-01

    Objective: Occupational lung disease due to silica dust is one of the most common work-related injuries. In denim sandblasting, workers are exposed to silica that may cause immediate mortality, especially in young people. The aim of this study was to assess the multidetector computed tomography (MDCT) findings of silicosis in denim sandblasters and to better define the role of MDCT in the early detection of silicosis. Materials and Methods: The study included 12 consecutive male patients who were admitted to a pulmonary outpatient clinic between April 2009 and December 2009. All patients had been working as sandblasters for at least one year. All patients underwent chest CT examinations for suspected silicosis. Two radiologists independently assessed the images for the presence and distribution of airspace consolidation, ground-glass opacity, nodules, interlobular septal thickening, parenchymal bands, fibrosis, masses, traction bronchiectasis, honeycombing, lobular low-attenuation areas, emphysema, pleural effusion or thickening, and mediastinal or hilar adenopathy. Results: MDCT detected parenchymal abnormalities in the lungs in eight (67%) of the twelve patients. The most common MDCT finding was ground glass opacity (58%). Other common findings were parencyhmal nodules and interlobular septal thickening, predominantly in the upper zones. Nodules were detected in six (50%) of the twelve patients. In four cases (67%), the nodules were numerous (>10), were predominantly smaller than 10 mm, and were centrilobular in distribution. In five (42%) of the 12 patients, interlobular septal thickening was detected. Only one (8%) patient presented with airspace consolidation; this was bilateral in the upper zones and associated with air bronchograms. In one (8%) patient there were several traction bronchiectases in the upper zones. None of the patients presented with pleural effusion, thickening, or honeycombing. Enlarged mediastinal nodes were identified in half of the

  16. Assessment of patient and occupational dose in established and new applications of MDCT fluoroscopy.

    PubMed

    Joemai, Raoul M S; Zweers, Dirk; Obermann, Wim R; Geleijns, Jacob

    2009-04-01

    This study aimed to assess patient dose and occupational dose in established and new applications of MDCT fluoroscopy. Electronic personal dosimeters were used to measure occupational dose equivalent. Effective patient dose was derived from the recorded dose-length product. Acquisition parameters that were observed during CT fluoroscopy (CTF) provided the basis for the estimation of an entrance skin dose profile. Two hundred ten CT-guided interventional procedures were included in the study. The median effective patient dose was 10 mSv (range, 0.1-235 mSv; 107 procedures). The median peak entrance skin dose was 0.4 Sv (0.1-2.1 Sv; 27 procedures). From 547 measurements of occupational dose equivalent, a median occupational effective dose of 3 muSv per procedure was derived for the interventional radiologists and 0.4 muSv per procedure for the assisting radiologists and radiology technologists. The estimated maximum occupational effective dose reached 0.4 mSv. The study revealed high effective patient doses, up to 235 mSv, mainly for relatively new applications such as CTF-guided radiofrequency ablations using MDCT, vertebroplasty, and percutaneous ethanol injections of tumors. Entrance doses were occasionally in the range of the warning level for deterministic skin effects but were always below the threshold for serious deterministic effects. The complexity of the procedure, expected benefits of the treatment, and general health state of the patient contribute to the justification of observed high effective patient doses.

  17. Evaluation of a single-pass continuous whole-body 16-MDCT protocol for patients with polytrauma.

    PubMed

    Nguyen, Duy; Platon, Alexandra; Shanmuganathan, Kathirkamanathan; Mirvis, Stuart E; Becker, Christoph D; Poletti, Pierre-Alexandre

    2009-01-01

    The purpose of this study was to compare a conventional multiregional MDCT protocol with two continuous single-pass whole-body MDCT protocols in imaging of patients with polytrauma. Ninety patients with polytrauma underwent whole-body 16-MDCT with a conventional (n=30) or one of two single-pass (n=60) protocols. The conventional protocol included unenhanced scans of the head and cervical spine and contrast-enhanced helical scans (140 mL, 4 mL/s, 300 mg I/mL) of the thorax and abdomen. The single-pass protocols consisted of unenhanced scans of the head followed by one-sweep acquisition from the circle of Willis through the pubic symphysis with a biphasic (150 mL, 6 and 4 mL/s, 300 mg I/mL) or monophasic (110 mL, 4 mL/s, 400 mg I/mL) injection. Acquisition times and interval delays between head, chest, and abdominal scans were recorded. Contrast enhancement was measured in the aortic arch, liver, spleen, and kidney. Diagnostic image quality in the same areas was assessed on a 4-point scale. Median acquisition times for the single-pass protocols were significantly shorter (-42.5%) than the acquisition time for the conventional protocol. No significant differences were found in mean enhancement values in the aorta, liver, spleen, and kidney for the three protocols. The image quality with both single-pass protocols was better than that with the conventional protocol in assessment of the mediastinum and cervical spine (p<0.05). There was no significant difference between the single-pass protocols. Use of single-pass continuous whole-body MDCT protocols can significantly decrease examination time for patients with polytrauma and improve image quality compared with a conventional serial scan protocol. Monophasic injection with highly concentrated contrast medium can reduce injection flow rate and should therefore be preferred to a biphasic injection technique.

  18. MDCT of the liver in obese patients: evaluation of a different method to optimize iodine dose.

    PubMed

    Rengo, Marco; Bellini, Davide; Businaro, Rita; Caruso, Damiano; Azzara, Gabriella; De Santis, Domenico; Picchia, Simona; Biondi, Tommaso; Eid, Marwen; Boschiero, Dario; Laghi, Andrea

    2017-04-27

    To prospectively compare two different approaches for estimating the amount of intravenous contrast media (CM) needed for multiphasic MDCT of the liver in obese patients. This single-center, HIPAA-compliant prospective study was approved by our Institutional Review Board. Ninety-six patients (55 men, 41 women), with a total of 42 hypovascular liver lesions, underwent MDCT of the liver. The amount of contrast medium injected was computed according to the patient's lean body weight which was estimated using either a bioimpedance device (Group A) or the James formula (Group B). The following variables were compared between the two groups: the amount of contrast medium injected (in grams of Iodine, gI), the contrast enhancement index (CEI) and the lesion-to-liver contrast-to-noise ratio. Protocols A and B yielded significant differences in the amount of CM injected (mean values 41.9 ± 4.41 gI in Group A vs. 35.9 ± 5.75 gI in Group B; P = 0.021). The mean CEI value and lesion-to-liver contrast-to-noise ratio measured on the portal phase were significantly higher with protocol A than with protocol B (P < 0.05). Our study shows that the adoption of a bioimpedance device in obese patients improves liver parenchymal enhancement and lesion conspicuity.

  19. Comparison between a new reconstruction algorithm (OPED) and filtered backprojection (FBP) for MDCT data

    NASA Astrophysics Data System (ADS)

    Renger, Bernhard; No"l, Peter B.; Tischenko, Oleg; Rummeny, Ernst J.; Hoeschen, Christoph

    2012-03-01

    Previously the Orthogonal Polynomial Expansion on the Disk (OPED) algorithm was presented. Further, in prototype experiments in combination with the CT D`or geometry feasibility was demonstrated. In this study we implemented OPED with a clinical Scanner, and evaluated the potential using phantom studies. All studies were acquired on a Siemens Somatom 64 (Erlangen, Germany) scanner, where raw projection data were reconstructed with the conventional FBP reconstruction and the OPED algorithm. OPED allows one to use fan beam geometry directly without any additional procedures such as interpolation or rebinning if using the CT D`or geometry. In particular, OPED describes an approximation of the image function as a sum of polynomials using Chebychev polynomials. For performance evaluation, the Catphan phantom 600 was imaged. OPED Images where reconstructed using C++ and MATLAB® .We measured uniformity, MTF and CNR for different dose levels and compared these to standard FBP images reconstructions with different filter kernels. The integration and interpretation of the MDCT projection data for the OPED algorithm was accomplished. Reconstruction time is about 6 s on Quad-Core 3 GHz Intel Xeon processor. Typical artifacts are reduced when applying OPED. Using OPED the MTF maintains constant over the whole FOV. Uniformity and CNR are equal compared to FBP. Advantages of OPED were demonstrated by applying the algorithm to projections images from a clinical MDCT scanner. In the future, we see OPED applications for low-dose or limited angle geometries to reduce the radiation dose while improving diagnostic quality of the reconstructed slices.

  20. Perfusion measurement in acute pancreatitis using dynamic perfusion MDCT.

    PubMed

    Bize, Pierre E; Platon, Alexandra; Becker, Christoph D; Poletti, Pierre-Alexandre

    2006-01-01

    Our objective was to determine whether MDCT with perfusion imaging could help in assessing the severity of acute pancreatitis in the initial phase of the disease. One hundred six patients with abdominal pain were prospectively enrolled in this study. Patients were separated into two groups: P1 (severe) and P2 (mild) acute pancreatitis. Mean perfusion value was 24.8 mL/100 mL/min in the P1 group and 50.5 mL/100 mL/min in the P2 group (p = 0.0016, significant). Our preliminary data suggest that pancreatic perfusion measurement using MDCT with perfusion imaging could help in assessing the severity of acute pancreatitis.

  1. 3-D segmentation of human sternum in lung MDCT images.

    PubMed

    Pazokifard, Banafsheh; Sowmya, Arcot

    2013-01-01

    A fully automatic novel algorithm is presented for accurate 3-D segmentation of the human sternum in lung multi detector computed tomography (MDCT) images. The segmentation result is refined by employing active contours to remove calcified costal cartilage that is attached to the sternum. For each dataset, costal notches (sternocostal joints) are localized in 3-D by using a sternum mask and positions of the costal notches on it as reference. The proposed algorithm for sternum segmentation was tested on 16 complete lung MDCT datasets and comparison of the segmentation results to the reference delineation provided by a radiologist, shows high sensitivity (92.49%) and specificity (99.51%) and small mean distance (dmean=1.07 mm). Total average of the Euclidean distance error for costal notches positioning in 3-D is 4.2 mm.

  2. [Preoperative T stage of non-small cell lung cancer: comparison of the efficacy of 64-MDCT versus 3.0T MR imaging].

    PubMed

    Tang, Wei; Wu, Ning; Ouyang, Han; Huang, Yao; Liu, Li; Li, Meng; Zhou, Lina; Xu, Xiaojuan

    2015-08-01

    To compare the diagnostic efficacies of 64-MDCT and 3.0-T MRI in determining the T stage of non-small cell lung cancer (NSCLC). Approval from the institutional ethics committee and informed consent from patients were obtained before the study started. 40 patients with NSCLC proved by pathology were enrolled in the study. All the 40 patients underwent non-enhanced MRI, enhanced MRI, and enhanced MDCT. Their T stages were preliminarily evaluated according to these imaging manifestations by 3 groups of experienced chest radiologists respectively, and correlated with that of postoperative pathology using the Kappa test. The diagnostic efficacies of these three imaging modalities for determining the T stage of NSCLC were compared using the McNemar test. The preoperative diagnostic accuracy rate for the T stage of NSCLC was 85.0% (34 of 40) by non-enhanced MRI, 87.5% (35 of 40) by enhanced MRI, and 80.0% (32 of 40) by enhanced CT, showing no significant differences between the non-enhanced MRI and enhanced CT, enhanced MRI and enhanced CT, and non-enhanced MRI and enhanced MRI for determining the T stage of NSCLC (P>0.05). Compared with the enhanced MDCT, non-enhanced MRI and enhanced MRI provide slightly superior diagnostic efficacy for the preoperative T staging of NSCLC. For the patients with intolerance to contrast medium on MDCT scan, 3.0T MRI may be an alternative for determining the preoperative T stage of NSCLC.

  3. Vascular involvement in periampullary tumors: MDCT, EUS, and CDU.

    PubMed

    Gusmini, S; Nicoletti, R; Martinenghi, C; Del Maschio, A

    2009-07-01

    In patients affected by periampullary tumors, surgical resection represents the only treatment with curative intent. Preoperative evaluation of vascular involvement is necessary to avoid surgical treatments unable of curative intent resection. The aim of our update article is to assess the performance of multidetector computed tomography (MDCT), endoscopic ultrasonography (EUS), and color Doppler ultrasonography (CDU) in the evaluation of vascular involvement of major peripancreatic vessels, in periampullary tumors, analyzing the current and past literature.

  4. Leukemias involving abdominal and pelvic lymph nodes: evaluation with contrast-enhanced MDCT.

    PubMed

    Zhang, Ge; Yang, Zhi-Gang; Bai, Jiao; Li, Yuan; Xu, Hua-Yan; Long, Qi-Hua

    2014-10-01

    To clarify features of lymph nodes associated with leukemia purposing to offer help for imaging diagnosis and differential diagnosis of leukemia. We retrospectively analyzed 47 patients with clinically proven leukemia involving the abdominal and pelvic lymph nodes. Of these 47 patients, 10 had acute myeloid leukemia, 9 had acute lymphocytic leukemia, and 28 had chronic lymphocytic leukemia. MDCT was used to determine lymph node features such as morphology, growth patterns, size, enhancement patterns, anatomical distribution, and manifestations in extramedullary organs. Incidence of leukemia was higher in men than in women. Enlarged lymph nodes were more frequently conglomerated in chronic lymphocytic leukemia (96.4%) than in acute myeloid leukemia (50%) and acute lymphocytic leukemia (55.6%; P < 0.05 for both). Lymph nodes associated with chronic lymphocytic leukemia were larger than those associated with acute myeloid and lymphocytic leukemias (P < 0.05 for both). The enlarged lymph nodes appeared homogeneous (80.9%) and homogeneous mixed with peripheral (19.1%). No statistically significant differences were observed between the three types of leukemias with respect to enhancement patterns (all P > 0.05). The lymph nodes commonly associated with these three leukemias were located in the lesser omentum, upper and lower para-aortic regions, and groin region. Our study showed that contrast-enhanced MDCT could accurately determine the enhancement patterns and anatomical distribution of lymph nodes associated with leukemia. Therefore, it is helpful for imaging diagnosis and differential diagnosis of leukemia.

  5. Emergency radiology: straightening of the cervical spine in MDCT after trauma—a sign of injury or normal variant?

    PubMed Central

    Deak, Zsuszsanna; Krtakovska, Aina; Ruschi, Francesco; Kammer, Nora; Wirth, Stefan; Reiser, Maximilian; Geyer, Lucas

    2016-01-01

    Objective: To evaluate whether straightening of the cervical spine (C-spine) alignment after trauma can be considered a significant multidetector CT (MDCT) finding. Methods: 160 consecutive patients after C-spine trauma admitted to a Level 1 trauma centre received MDCT according to Canadian Cervical Spine Rule and National Emergency X-Radiography Utilization Study indication rule; subgroups with and without cervical collar immobilization (CCI +/−) were compared with a control group (n = 20) of non-traumatized patients. Two independent readers evaluated retrospectively the alignment, determined the absolute rotational angle of the posterior surface of C2 and C7 (ARA C2–7) and grouped the results for lordosis (<−13°), straight (−13 to +6°) and kyphosis (>+6°). Results: In the two CCI−/CCI+ study groups, the straight or kyphotic alignment significantly (p = 0.001) predominated over lordosis. The number of patients with straight C-spine alignment was higher in the CCI+ group (CCI+ 69% vs CCI− 49%, p = 0.05). A comparison of the CCI+ group vs the CCI− group revealed a slightly smaller number of kyphotic (10% vs 18%, p = 0.34) and lordotic (21% vs 33%, p = 0.33) alignments. Statistically, however, the differences were of no significance. The control group revealed no significant differences. Conclusion: Straightening of the C-spine alone is not a definitive sign of injury but is a biomechanical variation due to CCI and neck positioning during MDCT or active patient control. Advances in knowledge: Straightening of the C-spine alignment in MDCT alone is not a definitive sign of injury. Straightening of the C-spine alignment is related to neck positioning and active patient control. CCI has a straightening effect on the cervical alignment. PMID:26764283

  6. Printed MDCT 3D models for prediction of Left Atrial Appendage (LAA) occluder device size - A feasibility study.

    PubMed

    Goitein, Orly; Fink, Noam; Guetta, Victor; Beinart, Roy; Brodov, Yafim; Konen, Eli; Goitein, David; Di Segni, Elio; Grupper, Avishay; Glikson, Michael

    2017-05-16

    Trans-esophageal echocardiography (TEE) and MDCT currently serve as imaging modalities for left atrial appendage (LAA) occlusion pre-procedural planning. We assessed the feasibility of multi-detector CT (MDCT) based models to predict the correct size of device for LAA occlusion procedures. Patients planned for LAA occlusion underwent MDCT before implantation, which was used for creating and printing 3D LAA models. Three cardiologists evaluated the 3D models and predicted the correct size of the device by manual manipulation, these predictions were compared with the actual device implanted during the procedure. Twenty nine patients were included in this study. Amplatzer™ and Watchman™ devices were deployed in 12 and 17 patients, respectively. Two procedures were aborted due to failure of occlusion, all three physicians predicted it. There was good correlation between the 3D models and the inserted device for Amplatzer™ devices with concordance correlation coefficient 0.778 (P=0.001) and poor agreement for Watchman™ devices - concordance correlation coefficient of 0.315 (P=0.203). Agreement between the three physicians for Amplatzer ™ and Watchman™ devices were excellent with a calculated average intra-class correlation of 0.915 and 0.816 respectively. We found LAA printed 3D models to be accurate for prediction of LAA occluder device size for Amplatzer™ device but not for Watchman™ device.

  7. Extramural venous invasion detected by MDCT as an adverse imaging feature for predicting synchronous metastases in T4 gastric cancer.

    PubMed

    Cheng, Jin; Wu, Jing; Ye, Yingjiang; Zhang, Chunfang; Zhang, Yinli; Wang, Yi

    2017-04-01

    Background Extramural venous invasion (EMVI) is defined histologically as the active invasion of tumor cells to the lumens of mesenteric vessels beyond the muscularis propria in advanced gastrointestinal cancer, resulting in distant metastases. Purpose To determine the association between synchronous metastatic disease in patients with T4 gastric cancer and EMVI detected on contrast-enhanced multiple-row detector computed tomography (MDCT). Material and Methods A total of 152 patients with T4 gastric carcinoma were retrospectively reviewed and divided into EMVI-positive and EMVI-negative groups where EMVI, as detected on MDCT, was defined as a tubular or nodular soft tissue thickening extending from the tumor along the vessels of the mesentery. Synchronous metastases were detected by MDCT and/or confirmed by postoperative diagnosis. Logistic regression analyses were performed to analyze the predictive factors of synchronous metastases in gastric cancer. Results Synchronous metastases were found in 47 of 152 (30.9%) patients with T4 gastric cancer. Thirty-one of 77 (40.3%) patients in the EMVI-positive group had evidence of metastases compared to 16 (21.3%) of 75 patients in the EMVI-negative group ( P = 0.019). Synchronous metastases were significantly associated with EMVI with an odds ratio (OR) of 2.250 (95% CI, 1.072-4.724). Conclusion EMVI-positive tumors, as an adverse imaging feature, were significantly associated with synchronous metastases in patients with T4 gastric cancer.

  8. High-pitch computed tomography of the lung in pediatric patients: an intraindividual comparison of image quality and radiation dose to conventional 64-MDCT.

    PubMed

    Tsiflikas, I; Thomas, C; Ketelsen, D; Seitz, G; Warmann, S; Claussen, C D; Schäfer, J F

    2014-06-01

    The aim of this study was to investigate frequencies of typical artifacts in low-dose pediatric lung examinations using high-pitch computed tomography (HPCT) compared to MDCT, and to estimate the effective radiation dose (Eeff). Institutional review board approval for this retrospective study was obtained. 35 patients (17 boys, 18 girls; mean age 112 ± 69 months) were included and underwent MDCT and follow-up scan by HPCT or vice versa (mean follow-up time 87 days), using the same tube voltage and current. The total artifact score (0 - 8) was defined as the sum of artifacts arising from movement, breathing or pulsation of the heart or pulmonary vessels (0 - no; 1 - moderate; 2 - severe artifacts). Eeff was estimated according to the European Guidelines on Quality Criteria for Multislice Computed Tomography. The Mann-Whitney U test was used to analyze differences between the patient groups. The Spearman's rank correlation coefficient was used for correlation of ordinal variables. The scan time was significantly lower for HPCT compared to MDCT (0.72 ± 0.13 s vs. 3.65 ± 0.81s; p < 0.0001). In 28 of 35 (80 %) HPCT examinations no artifacts were visible, whereas in MDCT artifacts occurred in all examinations. The frequency of pulsation artifacts and breathing artifacts was higher in MDCT compared to HPCT (100 % vs. 17 % and 31 % vs. 6 %). The total artifact score significantly correlated with the patient's age in MDCT (r = - 0.42; p = 0.01), but not in HPCT (r = - 0.32; p = 0.07). The estimated Eeff was significantly lower in HPCT than in MDCT (1.29 ± 0.31 vs. 1.47 ± 0.37 mSv; p < 0.0001). Our study indicates that the use of HPCT has advantages for pediatric lung imaging with a reduction of breathing and pulsation artifacts. Moreover, the estimated Eeff was lower. In addition, examinations can be performed without sedation or breath-hold without losing image quality. • Fewer artifacts in pediatric

  9. Feasibility of using single-slice MDCT to evaluate visceral abdominal fat in an urban pediatric population.

    PubMed

    Blitman, Netta M; Baron, Lindsay Stanton; Berkenblit, Robert G; Schoenfeld, Alan H; Markowitz, Morri; Freeman, Katherine

    2011-08-01

    Obesity is a growing clinical problem, especially among children of low socioeconomic status. Increased visceral abdominal fat is implicated in the metabolic syndrome and its health consequences. The purpose of this study is to validate measurement of a single MDCT slice as a predictor of total visceral abdominal fat and to correlate over a wide range of body mass indexes (BMIs). A two-phase retrospective analysis was performed. For validation, MDCTs of 21 consecutive healthy children (8-14 years old) were reviewed. In these cases, visceral abdominal fat and subcutaneous abdominal fat area were calculated using a body fat analysis function from single 0.625-mm MDCT slices at the umbilicus and were compared with total visceral abdominal fat area as measured from T11 to the coccyx. Subsequently, visceral abdominal fat area was obtained from single slices at the umbilicus from abdominal MDCT scans of 146 consecutive healthy children (age range, 6-14 years; 80 boys and 66 girls; 77 Hispanic, 41 African American, 15 white, and 13 multiracial or other race) for whom BMI was available. Associations between visceral abdominal fat area and sex, race, and BMI were determined. Effective radiation dose for a 1.25-mm axial MDCT slice was calculated using a mathematic model that uses derived scaling factors for pediatric patients. Visceral abdominal fat area obtained from a 0.625-mm slice at the umbilicus was highly correlated with total visceral abdominal fat area (r = 0.96; p < 0.0001). Visceral abdominal fat area from single slices at the umbilicus was significantly correlated with BMI (r = 0.72; p < 0.0001). Umbilical visceral abdominal fat area was significantly lower in African American children compared with others (median, 14 vs 22 cm(2); p = 0.02) and was not associated with sex. In our population, the effective radiation dose from the smallest obtainable slice was 0.015-0.019 mSv/37-54 kg of patient weight. Visceral abdominal fat area calculated from a single abdominal

  10. Comparing Learning from Observing and from Human Tutoring

    ERIC Educational Resources Information Center

    Muldner, Kasia; Lam, Rachel; Chi, Michelene T. H.

    2014-01-01

    A promising instructional approach corresponds to" learning by observing others learn" (i.e., by watching tutorial dialogue between a tutor and tutee). However, more work is needed to understand this approach's pedagogical utility. Thus, in 2 experiments we compared student learning from collaborative observation of dialogue with 2 other…

  11. Hi-Res scan mode in clinical MDCT systems: Experimental assessment of spatial resolution performance

    PubMed Central

    Cruz-Bastida, Juan P.; Gomez-Cardona, Daniel; Li, Ke; Sun, Heyi; Hsieh, Jiang; Szczykutowicz, Timothy P.; Chen, Guang-Hong

    2016-01-01

    Purpose: The introduction of a High-Resolution (Hi-Res) scan mode and another associated option that combines Hi-Res mode with the so-called High Definition (HD) reconstruction kernels (referred to as a Hi-Res/HD mode in this paper) in some multi-detector CT (MDCT) systems offers new opportunities to increase spatial resolution for some clinical applications that demand high spatial resolution. The purpose of this work was to quantify the in-plane spatial resolution along both the radial direction and tangential direction for the Hi-Res and Hi-Res/HD scan modes at different off-center positions. Methods: A technique was introduced and validated to address the signal saturation problem encountered in the attempt to quantify spatial resolution for the Hi-Res and Hi-Res/HD scan modes. Using the proposed method, the modulation transfer functions (MTFs) of a 64-slice MDCT system (Discovery CT750 HD, GE Healthcare) equipped with both Hi-Res and Hi-Res/HD modes were measured using a metal bead at nine different off-centered positions (0–16 cm with a step size of 2 cm); at each position, both conventional scans and Hi-Res scans were performed. For each type of scan and position, 80 repeated acquisitions were performed to reduce noise induced uncertainties in the MTF measurements. A total of 15 reconstruction kernels, including eight conventional kernels and seven HD kernels, were used to reconstruct CT images of the bead. An ex vivo animal study consisting of a bone fracture model was performed to corroborate the MTF results, as the detection of this high-contrast and high frequency task is predominantly determined by spatial resolution. Images of this animal model generated by different scan modes and reconstruction kernels were qualitatively compared with the MTF results. Results: At the centered position, the use of Hi-Res mode resulted in a slight improvement in the MTF; each HD kernel generated higher spatial resolution than its counterpart conventional kernel

  12. Hi-Res scan mode in clinical MDCT systems: Experimental assessment of spatial resolution performance.

    PubMed

    Cruz-Bastida, Juan P; Gomez-Cardona, Daniel; Li, Ke; Sun, Heyi; Hsieh, Jiang; Szczykutowicz, Timothy P; Chen, Guang-Hong

    2016-05-01

    The introduction of a High-Resolution (Hi-Res) scan mode and another associated option that combines Hi-Res mode with the so-called High Definition (HD) reconstruction kernels (referred to as a Hi-Res/HD mode in this paper) in some multi-detector CT (MDCT) systems offers new opportunities to increase spatial resolution for some clinical applications that demand high spatial resolution. The purpose of this work was to quantify the in-plane spatial resolution along both the radial direction and tangential direction for the Hi-Res and Hi-Res/HD scan modes at different off-center positions. A technique was introduced and validated to address the signal saturation problem encountered in the attempt to quantify spatial resolution for the Hi-Res and Hi-Res/HD scan modes. Using the proposed method, the modulation transfer functions (MTFs) of a 64-slice MDCT system (Discovery CT750 HD, GE Healthcare) equipped with both Hi-Res and Hi-Res/HD modes were measured using a metal bead at nine different off-centered positions (0-16 cm with a step size of 2 cm); at each position, both conventional scans and Hi-Res scans were performed. For each type of scan and position, 80 repeated acquisitions were performed to reduce noise induced uncertainties in the MTF measurements. A total of 15 reconstruction kernels, including eight conventional kernels and seven HD kernels, were used to reconstruct CT images of the bead. An ex vivo animal study consisting of a bone fracture model was performed to corroborate the MTF results, as the detection of this high-contrast and high frequency task is predominantly determined by spatial resolution. Images of this animal model generated by different scan modes and reconstruction kernels were qualitatively compared with the MTF results. At the centered position, the use of Hi-Res mode resulted in a slight improvement in the MTF; each HD kernel generated higher spatial resolution than its counterpart conventional kernel. However, the MTF along the

  13. Data compression in wireless sensors network using MDCT and embedded harmonic coding.

    PubMed

    Alsalaet, Jaafar K; Ali, Abduladhem A

    2015-05-01

    One of the major applications of wireless sensors networks (WSNs) is vibration measurement for the purpose of structural health monitoring and machinery fault diagnosis. WSNs have many advantages over the wired networks such as low cost and reduced setup time. However, the useful bandwidth is limited, as compared to wired networks, resulting in relatively low sampling. One solution to this problem is data compression which, in addition to enhancing sampling rate, saves valuable power of the wireless nodes. In this work, a data compression scheme, based on Modified Discrete Cosine Transform (MDCT) followed by Embedded Harmonic Components Coding (EHCC) is proposed to compress vibration signals. The EHCC is applied to exploit harmonic redundancy present is most vibration signals resulting in improved compression ratio. This scheme is made suitable for the tiny hardware of wireless nodes and it is proved to be fast and effective. The efficiency of the proposed scheme is investigated by conducting several experimental tests.

  14. "Lies, damned lies ..." and observational studies in comparative effectiveness research.

    PubMed

    Albert, Richard K

    2013-06-01

    A new federal initiative has allocated $1.1 billion to comparative effectiveness research, and many have emphasized the importance of including observational studies in this effort. The rationale for using observational studies to assess comparative effectiveness is based on concerns that randomized controlled trials (RCTs) are not "real world" because they enroll homogeneous patient populations, measure study outcomes that are not important to patients, use protocols that are overly complex, are conducted in specialized centers, and use study treatments that are not consistent with usual care, and that RCTs are not always feasible because of a lack of equipoise, the need to assess delayed endpoints, and concerns that they take years to complete and are expensive. This essay questions the validity of each of these proposed limitations, summarizes concerns raised about the accuracy of results generated by observational studies, provides some examples of discrepancies between results of observational studies and RCTs that pertain to pulmonary and critical care, and suggests that using observational studies for comparative effectiveness research may increase rather than decrease the cost of health care and may harm patients.

  15. MDCT of hand and wrist infections: emphasis on compartmental anatomy.

    PubMed

    Ahlawat, S; Corl, F M; LaPorte, D M; Fishman, E K; Fayad, L M

    2017-04-01

    Hand and wrist infections can present with a spectrum of manifestations ranging from cellulitis to deep-space collections. The various infectious processes can be categorised as superficial or deep infections based on their respective locations relative to the tendons. Superficial hand infections are located superficial to the tendons and are comprised of cellulitis, lymphangitis, paronychia, pulp-space infections, herpetic whitlow, and include volar as well as dorsal subcutaneous abscesses. Deep hand infections are located deep to the tendon sheaths and include synovial space infections, such as infectious tenosynovitis, deep fascial space infections, septic arthritis, necrotising fasciitis, and osteomyelitis. Knowledge of hand and wrist compartmental anatomy is essential for the accurate diagnosis and management of hand infections. Although early and superficial infections of the hand may respond to non-surgical management, most hand infections are surgical emergencies. Multidetector computed tomography (MDCT), with its muliplanar reformation (MPR) and three-dimensional (3D) capabilities, is a powerful tool in the emergency setting for the evaluation of acute hand and wrist pathology. The clinical and imaging features of hand and wrist infections as evident on MDCT will be reviewed with emphasis on contiguous and closed synovial and deep fascial spaces. Knowledge of hand compartmental anatomy enables accurate characterisation of the infectious process and localise the extent of disease in the acute setting. Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  16. MDCT imaging of the stomach: advances and applications.

    PubMed

    Nagpal, Prashant; Prakash, Anjali; Pradhan, Gaurav; Vidholia, Aditi; Nagpal, Nishant; Saboo, Sachin S; Kuehn, David M; Khandelwal, Ashish

    2017-01-01

    The stomach may be involved by a myriad of pathologies ranging from benign aetiologies like inflammation to malignant aetiologies like carcinoma or lymphoma. Multidetector CT (MDCT) of the stomach is the first-line imaging for patients with suspected gastric pathologies. Conventionally, CT imaging had the advantage of simultaneous detection of the mural and extramural disease extent, but advances in MDCT have allowed mucosal assessment by virtual endoscopy (VE). Also, better three-dimensional (3D) post-processing techniques have enabled more robust and accurate pre-operative planning in patients undergoing gastrectomy and even predict the response to surgery for patients undergoing laparoscopic sleeve gastrectomy for weight loss. The ability of CT to obtain stomach volume (for bariatric surgery patients) and 3D VE images depends on various patient and protocol factors that are important for a radiologist to understand. We review the appropriate CT imaging protocol in the patients with suspected gastric pathologies and highlight the imaging pearls of various gastric pathologies on CT and VE.

  17. Is multidetector computed tomography comparable to magnetic resonance imaging for assessment of lumbar foraminal stenosis?

    PubMed

    Kang, Woo Young; Ahn, Joong Mo; Lee, Joon Woo; Lee, Eugene; Bae, Yun Jung; Seo, Jiwoon; Kim, Junghoon; Kang, Heung Sik

    2017-02-01

    Background Both multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) are used for assessment of lumbar foraminal stenosis (LFS). Therefore, it is relevant to assess agreement between these imaging modalities. Purpose To determine intermodality, inter-, and intra-observer agreement for assessment of LFS on MDCT and MRI. Material and Methods A total of 120 foramina in 20 patients who visited our institution in January and February 2014 were evaluated by six radiologists with different levels of experience. Radiologists evaluated presence and severity of LFS on sagittal CT and MR images according to a previously published LFS grading system. Intermodality agreement was analyzed by using weighted kappa statistics, while inter- and intra-observer agreement were analyzed by using intraclass correlation coefficients (ICCs) and kappa statistics. Results Overall intermodality agreement was moderate to good (kappa, 0.478-0.765). In particular, two professors and one fellow tended to overestimate the degree of LFS on CT compared with MRI. For inter-observer agreement of all six observers, ICCs indicated excellent agreement for both CT (0.774) and MRI (0.771), while Fleiss' kappa values showed moderate agreement for CT (0.482) and MRI (0.575). There was better agreement between professors and fellows compared with residents. For intra-observer agreement, ICCs indicated excellent agreement, while kappa values showed good to excellent agreement for both CT and MRI. Conclusion MDCT was comparable to MRI for diagnosis and assessment of LFS, especially for experienced observers. However, there was a tendency to overestimate the degree of LFS on MDCT compared with MRI.

  18. A Comparative Study of Cloud Observation between Instrumental Measurements and Visual Observations

    NASA Astrophysics Data System (ADS)

    Park, Y. S.; Jeong, J. Y.; Park, D. O.; Kang, J. J.; Choi, B. C.

    2014-12-01

    The microphysical observations of clouds have been performed by human observers who record the amount, height, and type of cloud. However, the observational methods of clouds by human observers have their limitations due to its difficulties in the punctuality and weakness of assessment. The Automatic Cloud Observation System(ACOS) has been developed by NIMR to obtain continuous informationof the amount and height of clouds. A set of ACOS is composed of two cameras and the amounts and heights of clouds are retrieved from the sky images. Four sets of the ACOS were installed during last 4 years at four locations in South Korea. They are compared with cloud observation data from visual observations and instrumental measurements using ceilometers, radiometers, and another camera-type instrument named "Sky View". Recent two-year observation data are analyzed, focused on the differences of cloud amounts and heights between cloud observation methods.

  19. Mixed-radix Algorithm for the Computation of Forward and Inverse MDCT

    PubMed Central

    Wu, Jiasong; Shu, Huazhong; Senhadji, Lotfi; Luo, Limin

    2008-01-01

    The modified discrete cosine transform (MDCT) and inverse MDCT (IMDCT) are two of the most computational intensive operations in MPEG audio coding standards. A new mixed-radix algorithm for efficient computing the MDCT/IMDCT is presented. The proposed mixed-radix MDCT algorithm is composed of two recursive algorithms. The first algorithm, called the radix-2 decimation in frequency (DIF) algorithm, is obtained by decomposing an N-point MDCT into two MDCTs with the length N/2. The second algorithm, called the radix-3 decimation in time (DIT) algorithm, is obtained by decomposing an N-point MDCT into three MDCTs with the length N/3. Since the proposed MDCT algorithm is also expressed in the form of a simple sparse matrix factorization, the corresponding IMDCT algorithm can be easily derived by simply transposing the matrix factorization. Comparison of the proposed algorithm with some existing ones shows that our proposed algorithm is more suitable for parallel implementation and especially suitable for the layer III of MPEG-1 and MPEG-2 audio encoding and decoding. Moreover, the proposed algorithm can be easily extended to the multidimensional case by using the vector-radix method. PMID:21258639

  20. Comparing models of star formation simulating observed interacting galaxies

    NASA Astrophysics Data System (ADS)

    Quiroga, L. F.; Muñoz-Cuartas, J. C.; Rodrigues, I.

    2017-07-01

    In this work, we make a comparison between different models of star formation to reproduce observed interacting galaxies. We use observational data to model the evolution of a pair of galaxies undergoing a minor merger. Minor mergers represent situations weakly deviated from the equilibrium configuration but significant changes in star fomation (SF) efficiency can take place, then, minor mergers provide an unique scene to study SF in galaxies in a realistic but yet simple way. Reproducing observed systems also give us the opportunity to compare the results of the simulations with observations, which at the end can be used as probes to characterize the models of SF implemented in the comparison. In this work we compare two different star formation recipes implemented in Gadget3 and GIZMO codes. Both codes share the same numerical background, and differences arise mainly in the star formation recipe they use. We use observations from Pico dos Días and GEMINI telescopes and show how we use observational data of the interacting pair in AM2229-735 to characterize the interacting pair. Later we use this information to simulate the evolution of the system to finally reproduce the observations: Mass distribution, morphology and main features of the merger-induced star formation burst. We show that both methods manage to reproduce roughly the star formation activity. We show, through a careful study, that resolution plays a major role in the reproducibility of the system. In that sense, star formation recipe implemented in GIZMO code has shown a more robust performance. Acknowledgements: This work is supported by Colciencias, Doctorado Nacional - 617 program.

  1. MDCT for automated detection and measurement of pneumothoraces in trauma patients.

    PubMed

    Cai, Wenli; Tabbara, Malek; Takata, Noboru; Yoshida, Hiroyuki; Harris, Gordon J; Novelline, Robert A; de Moya, Marc

    2009-03-01

    The size of a pneumothorax is an important index to guide the emergency treatment of trauma patients--chest tube drainage. The purpose of this study was to develop and validate an automated computer-aided volumetry scheme for detection and measurement of pneumothoraces for trauma patients imaged with MDCT. Three pigs and 68 trauma patients with at least one diagnosed occult pneumothorax (23 women and 45 men; age range, 14-89 years; mean age, 41 +/- 19 years) were selected for the development and validation of our computer-aided volumetry scheme for pneumothorax. Computer-aided volumetry of pneumothorax consisted of five automated steps: extraction of pleural region, detection of pneumothorax candidates, delineation of the detected pneumothorax candidates, reduction of false-positive findings, and report of the volumetric measurement of pneumothoraces. In the animal study, our computer-aided volumetry scheme yielded a mean value of 24.27 +/- 0.64 mL (SD) compared with 25 mL of air volume manually injected in each scan. The correlation coefficients were 0.999 and 0.997 for the in vivo and ex vivo comparison, respectively. In the patient study, the sensitivity of our computer-aided volumetry scheme was 100% with a false-positive rate of 0.15 per case for 32 occult pneumothoraces > or = 25 mL. The correlation coefficient was 0.999 for manual volumetry comparison. This automated computer-aided volumetry scheme took approximately 3 minutes to finish the detection and measurement per case. The results show that our computer-aided volumetry scheme provides an automated method for accurate and efficient detection and measurement of pneumothoraces in MDCT images of trauma patients.

  2. MHD models compared with Artemis observations at -60 Re

    NASA Astrophysics Data System (ADS)

    Gencturk Akay, Iklim; Sibeck, David; Angelopoulos, Vassilis; Kaymaz, Zerefsan; Kuznetsova, Maria

    2016-07-01

    The distant magnetotail has been one of the least studied magnetic regions of the Earth's magnetosphere compared to the other near Earth both dayside and nightside magnetospheric regions owing to the limited number of spacecraft observations. Since 2011, ARTEMIS spacecraft give an excellent opportunity to study the magnetotail at lunar distances in terms of data quality and parameter space. This also gives opportunities to improve the magnetotail models at -60 Re and encourages the modelling studies of the distant magnetotail. Using ARTEMIS data in distant magnetotail, we create magnetic field and plasma flow vector maps in different planes and separated with IMF orientation to understand the magnetotail dynamics at this distance. For this study, we use CCMC's Run-on-Request resources of the MHD models; specifically SWMF-BATS-R-US, OpenGGCM, and LFM and perform the similar analysis with the models. Our main purpose in this study is to measure the performance of the MHD models at -60 Re distant magnetotail by comparing the model results with Artemis observations. In the literature, such a comprehensive comparative study is lacking in the distant tail. Preliminary results show that in general all three models underestimate the magnetic field structure while overestimating the flow speed. In the cross-sectional view, LFM seems to produce the better agreement with the observations. A clear dipolar magnetic field structure is seen with dawn-dusk asymmetry in all models owing to slight positive IMF By but the effect was found to be exaggerated. All models show tailward flows at this distance of the magnetotail, most possibly owing to the magnetic reconnection at the near Earth tail distances. A detailed comparison of several tail characteristics from the models will be presented and discussions will be given with respect to the observations from Artemis at this distance.

  3. MDCT arthrography of the hip: value of the adaptive statistical iterative reconstruction technique and potential for radiation dose reduction.

    PubMed

    Tobalem, Frank; Dugert, Eric; Verdun, Francis R; Dunet, Vincent; Ott, Julien G; Rudiger, Hannes A; Cherix, Stephane; Meuli, Reto; Becce, Fabio

    2014-12-01

    The purpose of this article is to assess the effect of the adaptive statistical iterative reconstruction (ASIR) technique on image quality in hip MDCT arthrography and to evaluate its potential for reducing radiation dose. Thirty-seven patients examined with hip MDCT arthrography were prospectively randomized into three different protocols: one with a regular dose (volume CT dose index [CTDIvol], 38.4 mGy) and two with a reduced dose (CTDIvol, 24.6 or 15.4 mGy). Images were reconstructed using filtered back projection (FBP) and four increasing percentages of ASIR (30%, 50%, 70%, and 90%). Image noise and contrast-to-noise ratio (CNR) were measured. Two musculoskeletal radiologists independently evaluated several anatomic structures and image quality parameters using a 4-point scale. They also jointly assessed acetabular labrum tears and articular cartilage lesions. With decreasing radiation dose level, image noise statistically significantly increased (p=0.0009) and CNR statistically significantly decreased (p=0.001). We also found a statistically significant reduction in noise (p=0.0001) and increase in CNR (p≤0.003) with increasing percentage of ASIR; in addition, we noted statistically significant increases in image quality scores for the labrum and cartilage, subchondral bone, overall diagnostic quality (up to 50% ASIR), and subjective noise (p≤0.04), and statistically significant reductions for the trabecular bone and muscles (p≤0.03). Regardless of the radiation dose level, there were no statistically significant differences in the detection and characterization of labral tears (n=24; p=1) and cartilage lesions (n=40; p≥0.89) depending on the ASIR percentage. The use of up to 50% ASIR in hip MDCT arthrography helps to reduce radiation dose by approximately 35-60%, while maintaining diagnostic image quality comparable to that of a regular-dose protocol using FBP.

  4. MDCT of extranodal mantle cell lymphoma: a single institute experience.

    PubMed

    Baheti, Akshay D; Tirumani, Sree Harsha; Sewatkar, Rani; Sachin, Saboo S; Shinagare, Atul B; Ramaiya, Nikhil H

    2015-08-01

    To study the pattern of extranodal and particularly gastrointestinal (GI) involvement of mantle cell lymphoma (MCL) on MDCT MATERIALS AND METHODS: In this IRB-approved, HIPAA compliant retrospective study, MDCT features of 78 patients (62 males and 16 females, mean age 57 years) with MCL including 28 patients at presentation were reviewed. Clinical and histopathological (blastoid vs. non-blastoid) data were noted from medical records. Extranodal involvement was present in overall 51/78 patients on CT (65%), 18/28 (64%) patients at presentation. Spleen (21/78-27%) and bowel (19/78-24%) were the most common sites of extranodal involvement by MCL on imaging, followed by lungs (10/78-13%) and skin/subcutaneous tissue (9/78-12%). Bowel involvement was either in the form of endophytic polypoidal lesions (n = 11, mean size 3.1 cm), as focal mild bowel wall thickening (n = 5, mean thickness 1.4 cm), or as combination of the two (n = 3). Blastoid histology was present in 14/78 (24%) patients and was statistically associated with skin/subcutaneous involvement (p < 0.05; Fisher's exact t test). Median follow-up was 72 months during which 21 patients died with median survival of 48 months (26 months for blastoid histology vs. 47 months for non-blastoid histology). There was no statistical correlation between sites of involvement and survival. MCL has a predilection for extranodal disease, predominantly involving the spleen, bowel, lungs, and subcutaneous tissue. GI involvement on CT is in the form of endoluminal polypoidal lesions and mild bowel wall thickening. Skin/subcutaneous involvement was statistically more common with blastoid histology in our study.

  5. Arterial double-contrast dual-energy MDCT: in-vivo rabbit atherosclerosis with iodinated nanoparticles and gadolinium agents

    NASA Astrophysics Data System (ADS)

    Carmi, Raz; Kafri, Galit; Altman, Ami; Goshen, Liran; Planer, David; Sosna, Jacob

    2010-03-01

    An in-vivo feasibility study of potentially improved atherosclerosis CT imaging is presented. By administration of two different contrast agents to rabbits with induced atherosclerotic plaques we aim at identifying both soft plaque and vessel lumen simultaneously. Initial injection of iodinated nanoparticle (INP) contrast agent (N1177 - Nanoscan Imaging), two to four hours before scan, leads to its later accumulation in macrophage-rich soft plaque, while a second gadolinium contrast agent (Magnevist) injected immediately prior to the scan blends with the aortic blood. The distinction between the two agents in a single scan is achieved with a double-layer dual-energy MDCT (Philips Healthcare) following material separation analysis using the reconstructed images of the different x-ray spectra. A single contrast agent injection scan, where only INP was injected two hours prior to the scan, was compared to a double-contrast scan taken four hours after INP injection and immediately after gadolinium injection. On the single contrast agent scan we observed along the aorta walls, localized iodine accumulation which can point on INP uptake by atherosclerotic plaque. In the double-contrast scan the gadolinium contributes a clearer depiction of the vessel lumen in addition to the lasting INP presence. The material separation shows a good correlation to the pathologies inferred from the conventional CT images of the two different scans while performing only a single scan prevents miss-registration problems and reduces radiation dose. These results suggest that a double-contrast dual-energy CT may be used for advanced clinical diagnostic applications.

  6. Polyarteritis nodosa: MDCT as a 'One-Stop Shop' Modality for Whole-Body Arterial Evaluation

    SciTech Connect

    Tsai, W.-L.; Tsai, I-C.; Lee Tain; Hsieh, C.-W.

    2008-07-15

    Polyarteritis nodosa is a rare disease, which is characterized by aneurysm formation and occlusion in the arteries of multiple systems. Due to its extensive involvement, whole-body evaluation is necessary for diagnosis and treatment monitoring. We report a case of polyarteritis nodosa using multidetector-row computed tomography (MDCT) as a 'one-stop shop' modality for whole-body arterial evaluation. With precise protocol design, MDCT can be used as a reliable noninvasive modality providing comprehensive whole-body arterial evaluation.

  7. Halo Coronal Mass Ejections: Comparing Observations and Models

    NASA Technical Reports Server (NTRS)

    Gilbert, Holly; Orlove, Matthew; SaintCyr, O.; Mays, L.; Gopalswamy, N.

    2011-01-01

    Since 1996, the SOHO LASCO coronagraphs have detected "halo" CMEs that appear to be directed toward Earth, but information about the size and speed of these events seen face-on has been limited. From a single vantage point along the Sun-Earth line, the primary limitation has been ambiguity in fitting the cone model (or other forward-modeling techniques, e.g., Thernisian et al., 2006). But in the past few years, the STEREO mission has provided a view of Earth-directed events from the side. These events offer the opportunity to compare measurements (width and speed) of halo CMEs observed by STEREO with models that derive halo CME properties. We report here results of such a comparison on a large sample of LASCO CMEs in the STEREO era.

  8. Comparing soil moisture memory in satellite observations and models

    NASA Astrophysics Data System (ADS)

    Stacke, Tobias; Hagemann, Stefan; Loew, Alexander

    2013-04-01

    A major obstacle to a correct parametrization of soil processes in large scale global land surface models is the lack of long term soil moisture observations for large parts of the globe. Currently, a compilation of soil moisture data derived from a range of satellites is released by the ESA Climate Change Initiative (ECV_SM). Comprising the period from 1978 until 2010, it provides the opportunity to compute climatological relevant statistics on a quasi-global scale and to compare these to the output of climate models. Our study is focused on the investigation of soil moisture memory in satellite observations and models. As a proxy for memory we compute the autocorrelation length (ACL) of the available satellite data and the uppermost soil layer of the models. Additional to the ECV_SM data, AMSR-E soil moisture is used as observational estimate. Simulated soil moisture fields are taken from ERA-Interim reanalysis and generated with the land surface model JSBACH, which was driven with quasi-observational meteorological forcing data. The satellite data show ACLs between one week and one month for the greater part of the land surface while the models simulate a longer memory of up to two months. Some pattern are similar in models and observations, e.g. a longer memory in the Sahel Zone and the Arabian Peninsula, but the models are not able to reproduce regions with a very short ACL of just a few days. If the long term seasonality is subtracted from the data the memory is strongly shortened, indicating the importance of seasonal variations for the memory in most regions. Furthermore, we analyze the change of soil moisture memory in the different soil layers of the models to investigate to which extent the surface soil moisture includes information about the whole soil column. A first analysis reveals that the ACL is increasing for deeper layers. However, its increase is stronger in the soil moisture anomaly than in its absolute values and the first even exceeds the

  9. Comparative Structure of Saturn's Rings from Cassini Radio Occultation Observations

    NASA Astrophysics Data System (ADS)

    Marouf, Essam A.; French, R. G.; Rappaport, N. J.; McGhee, C. A.; Wong, K.; Thomson, F. S.; Anabtawi, A.

    2007-10-01

    Radio occultations of Saturn's rings during the Cassini prime mission fall into three main groups, depending on the rings opening angle B. The first is a set of eight diametric occultations completed early in the mission (March-September/2005) when |B| was relatively large (19.5 to 23.5°). They permitted multiple-longitude profiling of relatively optically thick ring features, revealing detailed structure of enigmatic Ring B. The second is to be completed late in the mission when the rings are relatively closed (|B| < 10°). They will provide enhanced sensitivity to tenuous ring material, hence complementary information about small optical depth structure. Bridging the two groups is a third composed of two specially designed occultations recently completed (May-June/2007). They capture the intermediate range |B| 15°. Because the rings were still reasonably open, much of the structure was profiled. The different occultation geometry from the diametric group provided enhanced sensitivity to bending waves and other inclined features. We comparatively consider variability (or lack of) of observed ring structure with B and longitude. The variability when present can be true (dynamically forced features) or apparent (azimuthal asymmetry due to preferentially aligned gravitational wakes). The multiple-longitude coverage provides rich characterization of the true variability, including remarkable variations in the morphology of gap-embedded ringlets in Ring C, clear variations in the width of gaps in the Cassini Division, wavelike features in Ring C (the "Rosen Waves"), classical satellite wake profiles due to Pan, in addition to many density and few bending waves. For the apparent asymmetry, observed optical depth variations with B, viewing geometry, and wavelength constrain physical properties of the rings microstructure (particle sizes, particle-cluster sizes and orientation, spatial cluster density, vertical ring profile and physical thickness, ...). Complementary

  10. Comparing the incomparable: hemodialysis versus peritoneal dialysis in observational studies.

    PubMed

    Foley, Robert N

    2004-01-01

    A randomized trial comparing survival in hemodialysis and peritoneal dialysis remains a utopian aspiration. Dialysis is still relatively rare on a population basis, and a natural tension exists between desirability and feasibility in terms of quality of evidence. In practice, it is very difficult to perform prospective comparisons with large groups of contemporary representative subjects, and much of the literature comes from retrospective national registries. This article considers several questions to address when trying to compare the outcomes of peritoneal dialysis and hemodialysis. Prognostic similarity at baseline is a fundamental issue. Traditionally, adjustment for known prognostic factors has been used in an attempt to minimize the bias caused by nonrandom treatment assignment. Propensity scores have been suggested to be superior, and matched-case analysis may also be a useful method for comparison. Other questions include, when, in relation to starting dialysis, to start the observation clock; the definition and handling of switches of dialysis therapy; and the decision to censor at transplantation. Finally, comparisons are complicated by hazards ratios that vary over time, and time-segmented analysis is obligatory. Many types of analytical approaches are needed to begin to appreciate outcome disparities between dialysis therapies.

  11. MDCT Linear and Volumetric Analysis of Adrenal Glands: Normative Data and Multiparametric Assessment.

    PubMed

    Carsin-Vu, Aline; Oubaya, Nadia; Mulé, Sébastien; Janvier, Annaëlle; Delemer, Brigitte; Soyer, Philippe; Hoeffel, Christine

    2016-08-01

    To study linear and volumetric adrenal measurements, their reproducibility, and correlations between total adrenal volume (TAV) and adrenal micronodularity, age, gender, body mass index (BMI), visceral (VAAT) and subcutaneous adipose tissue volume (SAAT), presence of diabetes, chronic alcoholic abuse and chronic inflammatory disease (CID). We included 154 patients (M/F, 65/89; mean age, 57 years) undergoing abdominal multidetector row computed tomography (MDCT). Two radiologists prospectively independently performed adrenal linear and volumetric measurements with semi-automatic software. Inter-observer reliability was studied using inter-observer correlation coefficient (ICC). Relationships between TAV and associated factors were studied using bivariate and multivariable analysis. Mean TAV was 8.4 ± 2.7 cm(3) (3.3-18.7 cm(3)). ICC was excellent for TAV (0.97; 95 % CI: 0.96-0.98) and moderate to good for linear measurements. TAV was significantly greater in men (p < 0.0001), alcoholics (p = 0.04), diabetics (p = 0.0003) and those with micronodular glands (p = 0.001). TAV was lower in CID patients (p = 0.0001). TAV correlated positively with VAAT (r = 0.53, p < 0.0001), BMI (r = 0.42, p < 0.0001), SAAT (r = 0.29, p = 0.0003) and age (r = 0.23, p = 0.005). Multivariable analysis revealed gender, micronodularity, diabetes, age and BMI as independent factors influencing TAV. Adrenal gland MDCT-based volumetric measurements are more reproducible than linear measurements. Gender, micronodularity, age, BMI and diabetes independently influence TAV. • Volumetric measurements are more reproducible than linear measurements for adrenal glands. • Inter-observer reproducibility of adrenal gland volume is excellent using semiautomatic software. • Gender, age, BMI, and diabetes independently influence total adrenal gland volume. • Adrenal micronodularity is associated with increased total adrenal gland volume.

  12. MDCT quantification is the dominant parameter in decision–making regarding chest tube drainage for stable patients with traumatic pneumothorax

    PubMed Central

    Cai, Wenli; Lee, June-Goo; Fikry, Karim; Yoshida, Hiroyuki; Novelline, Robert; de Moya, Marc

    2013-01-01

    It is commonly believed that the size of a pneumothorax is an important determinant of treatment decision, in particular regarding whether chest tube drainage (CTD) is required. However, the volumetric quantification of pneumothoraces has not routinely been performed in clinics. In this paper, we introduced an automated computer-aided volumetry (CAV) scheme for quantification of volume of pneumothoraces in chest multi-detect CT (MDCT) images. Moreover, we investigated the impact of accurate volume of pneumothoraces in the improvement of the performance in decision-making regarding CTD in the management of traumatic pneumothoraces. For this purpose, an occurrence frequency map was calculated for quantitative analysis of the importance of each clinical parameter in the decision-making regarding CTD by a computer simulation of decision-making using a genetic algorithm (GA) and a support vector machine (SVM). A total of 14 clinical parameters, including volume of pneumothorax calculated by our CAV scheme, was collected as parameters available for decision-making. The results showed that volume was the dominant parameter in decision-making regarding CTD, with an occurrence frequency value of 1.00. The results also indicated that the inclusion of volume provided the best performance that was statistically significant compared to the other tests in which volume was excluded from the clinical parameters. This study provides the scientific evidence for the application of CAV scheme in MDCT volumetric quantification of pneumothoraces in the management of clinically stable chest trauma patients with traumatic pneumothorax. PMID:22560899

  13. Impact of bowtie filter and object position on the two-dimensional noise power spectrum of a clinical MDCT system

    PubMed Central

    Gomez-Cardona, Daniel; Cruz-Bastida, Juan Pablo; Li, Ke; Budde, Adam; Hsieh, Jiang; Chen, Guang-Hong

    2016-01-01

    Purpose: Noise characteristics of clinical multidetector CT (MDCT) systems can be quantified by the noise power spectrum (NPS). Although the NPS of CT has been extensively studied in the past few decades, the joint impact of the bowtie filter and object position on the NPS has not been systematically investigated. This work studies the interplay of these two factors on the two dimensional (2D) local NPS of a clinical CT system that uses the filtered backprojection algorithm for image reconstruction. Methods: A generalized NPS model was developed to account for the impact of the bowtie filter and image object location in the scan field-of-view (SFOV). For a given bowtie filter, image object, and its location in the SFOV, the shape and rotational symmetries of the 2D local NPS were directly computed from the NPS model without going through the image reconstruction process. The obtained NPS was then compared with the measured NPSs from the reconstructed noise-only CT images in both numerical phantom simulation studies and experimental phantom studies using a clinical MDCT scanner. The shape and the associated symmetry of the 2D NPS were classified by borrowing the well-known atomic spectral symbols s, p, and d, which correspond to circular, dumbbell, and cloverleaf symmetries, respectively, of the wave function of electrons in an atom. Finally, simulated bar patterns were embedded into experimentally acquired noise backgrounds to demonstrate the impact of different NPS symmetries on the visual perception of the object. Results: (1) For a central region in a centered cylindrical object, an s-wave symmetry was always present in the NPS, no matter whether the bowtie filter was present or not. In contrast, for a peripheral region in a centered object, the symmetry of its NPS was highly dependent on the bowtie filter, and both p-wave symmetry and d-wave symmetry were observed in the NPS. (2) For a centered region-ofinterest (ROI) in an off-centered object, the symmetry of

  14. Methylphenidate in Pregnancy: A Multicenter, Prospective, Comparative, Observational Study.

    PubMed

    Diav-Citrin, Orna; Shechtman, Svetlana; Arnon, Judy; Wajnberg, Rebecka; Borisch, Cornelia; Beck, Evelin; Richardson, Jonathan Luke; Bozzo, Pina; Nulman, Irena; Ornoy, Asher

    2016-09-01

    Methylphenidate is a central nervous system stimulant medicinally used in the treatment of attention-deficit disorder with or without hyperactivity (ADD/ADHD). Data on its use in human pregnancy are limited. The primary objective of the study was to evaluate the risk of major congenital anomalies after pregnancy exposure to methylphenidate for medical indications. In a prospective, comparative, multicenter observational study performed in 4 participating Teratology Information Services (in Jerusalem, Berlin, Newcastle upon Tyne, and Toronto) between 1996 and 2013, methylphenidate-exposed pregnancies were compared with pregnancies counseled for nonteratogenic exposure (NTE) after matching by maternal age, gestational age, and year at initial contact. 382 methylphenidate-exposed pregnancies (89.5% in the first trimester) were followed up. The overall rate of major congenital anomalies was similar between the groups (10/309 = 3.2% [methylphenidate] vs 13/358 = 3.6% [NTE], P = .780). The rates of major congenital anomalies (6/247 = 2.4% [methylphenidate] vs 12/358 = 3.4% [NTE], P = .511) and cardiovascular anomalies (2/247 = 0.8% [methylphenidate] vs 3/358 = 0.8% [NTE], P = .970) were also similar after exclusion of genetic or cytogenetic anomalies and limiting methylphenidate exposure to the period of organogenesis (weeks 4-13 after the last menstrual period). There was a higher rate of miscarriages and elective terminations of pregnancy in the methylphenidate group. Significant predictors for the miscarriages using Cox proportional hazards model were methylphenidate exposure (adjusted hazard ratio [HR] = 1.98; 95% CI, 1.23-3.20; P = .005) and past miscarriage (adjusted HR = 1.35; 95% CI, 1.18-1.55; P < .001). The present study suggests that methylphenidate does not seem to increase the risk for major malformations. Further studies are required to establish its pregnancy safety and its possible association with miscarriages.

  15. Influence of radiation dose and reconstruction algorithm in MDCT assessment of airway wall thickness: A phantom study

    SciTech Connect

    Gomez-Cardona, Daniel; Nagle, Scott K.; Li, Ke; Chen, Guang-Hong; Robinson, Terry E.

    2015-10-15

    Purpose: Wall thickness (WT) is an airway feature of great interest for the assessment of morphological changes in the lung parenchyma. Multidetector computed tomography (MDCT) has recently been used to evaluate airway WT, but the potential risk of radiation-induced carcinogenesis—particularly in younger patients—might limit a wider use of this imaging method in clinical practice. The recent commercial implementation of the statistical model-based iterative reconstruction (MBIR) algorithm, instead of the conventional filtered back projection (FBP) algorithm, has enabled considerable radiation dose reduction in many other clinical applications of MDCT. The purpose of this work was to study the impact of radiation dose and MBIR in the MDCT assessment of airway WT. Methods: An airway phantom was scanned using a clinical MDCT system (Discovery CT750 HD, GE Healthcare) at 4 kV levels and 5 mAs levels. Both FBP and a commercial implementation of MBIR (Veo{sup TM}, GE Healthcare) were used to reconstruct CT images of the airways. For each kV–mAs combination and each reconstruction algorithm, the contrast-to-noise ratio (CNR) of the airways was measured, and the WT of each airway was measured and compared with the nominal value; the relative bias and the angular standard deviation in the measured WT were calculated. For each airway and reconstruction algorithm, the overall performance of WT quantification across all of the 20 kV–mAs combinations was quantified by the sum of squares (SSQs) of the difference between the measured and nominal WT values. Finally, the particular kV–mAs combination and reconstruction algorithm that minimized radiation dose while still achieving a reference WT quantification accuracy level was chosen as the optimal acquisition and reconstruction settings. Results: The wall thicknesses of seven airways of different sizes were analyzed in the study. Compared with FBP, MBIR improved the CNR of the airways, particularly at low radiation dose

  16. Comparative observations on inorganic and organic lead neurotoxicity

    SciTech Connect

    Verity, M.A. )

    1990-11-01

    Environmental and occupational exposure to lead still generates concern, and recent studies have focused such concern on the role of body burden of lead during the fetal/neonatal period, especially in the genesis of disturbed central nervous system development. This discussion provides some comparative observations on the neurotoxicity of inorganic and organic lead species. The characteristic acute, predominantly cerebellar encephalopathy associated with neonatal high lead exposure contrasts to the subtle, axo-dendritic disorganization shown to be associated with low-level neonatal inorganic Pb{sup 2+} exposure. There is a preferential involvement of the hippocampus in both low-level inorganic Pb{sup 2+} and organolead exposure, and the clinical syndromes of irritability, hyperactivity, aggression, and seizures are common features of disturbed hippocampal function. Neurotransmitter system abnormalities have been described with inorganic Pb{sup 2+}, but recent attention has focused on the abnormalities in glutamate, dopamine, and/or {gamma}-aminobutyric acid (GABA) uptake, efflux, and metabolism. Abnormalities of GABA and glutamate metabolism are also found with the organolead species. Testable hypotheses are presented that may provide an understanding of the pathogenesis underlying dystrophic neuronal development under the influence of inorganic or organolead intoxication.

  17. MDCT of the S-shaped sinoatrial node artery.

    PubMed

    Saremi, Farhood; Channual, Stephanie; Abolhoda, Amir; Gurudevan, Swaminatha V; Narula, Jagat; Milliken, Jeffrey C

    2008-06-01

    The purpose of this study was to use 64-MDCT to investigate the anatomic characteristics of the S-shaped variant of the sinoatrial node (SAN) artery and to describe the clinical implications of the findings in ablative procedures involving the left atrium. Coronary CT angiograms of 250 patients (152 men, 98 women; mean age, 60 +/- 12 [SD] years) were retrospectively analyzed for identification of the origin, number, anatomic course, mode of termination, and S-shaped variant of the SAN artery. At least one SAN artery was detected in 244 patients. The S-shaped variant was seen in 35 (14.3%) of these patients. Thirty-four of the variants (30.6% of all left SAN arteries) arose from the proximal to middle portion of the left circumflex artery (mean distance between the ostium of the left circumflex artery and the origin of S-shaped variant, 28.7 +/- 13.1 mm). The other variant (0.7% of all right SAN arteries) originated from the distal right coronary artery. The S-shaped variant was the only artery supplying the SAN in 28 (11.4%) of the patients. In patients with two arteries supplying the SAN, the right SAN artery and the S-shaped variant of the left SAN artery were seen together in seven patients. The S-shaped SAN artery (mean distance from atrial wall, 2.43 +/- 0.992 mm) had a predictable proximal course, lying in the posterior aspect in a groove between the orifices of the left superior pulmonary vein and the left atrial appendage close to the left atrial wall. The terminal segment of the artery approached the nodal tissue posterior to the superior vena cava in 22 patients, anterior to the vena cava in 10 patients, and through branches surrounding the vena cava in two patients. The S-shaped variation of the SAN artery is common and has a characteristic anatomic course. MDCT can be used to plan surgical and catheter-based left atrial interventions in which this artery is at risk of injury.

  18. Three-dimensional reconstruction of upper airways from MDCT

    NASA Astrophysics Data System (ADS)

    Perchet, Diane; Fetita, Catalin; Preteux, Francoise

    2005-03-01

    Under the framework of clinical respiratory investigation, providing accurate modalities for morpho-functional analysis is essential for diagnosis improvement, surgical planning and follow-up. This paper focuses on the upper airways investigation and develops an automated approach for 3D mesh reconstruction from MDCT acquisitions. In order to overcome the difficulties related to the complex morphology of the upper airways and to the image gray level heterogeneity of the airway lumens and thin bony septa, the proposed 3D reconstruction methodology combines 2D segmentation and 3D surface regularization approaches. The segmentation algorithm relies on mathematical morphology theory and provides airway lumen robust discrimination from the surrounding tissues, while preserving the connectivity relationship between the different anatomical structures. The 3D regularization step uses an energy-based modeling in order to achieve a smooth and well-fitted 3D surface of the upper airways. An accurate 3D mesh representation of the reconstructed airways makes it possible to develop specific clinical applications such as virtual endoscopy, surgical planning and computer assisted intervention. In addition, building up patient-specific 3D models of upper airways is highly valuable for the study and design of inhaled medication delivery via computational fluid dynamics (CFD) simulations.

  19. Accurate 3D quantification of the bronchial parameters in MDCT

    NASA Astrophysics Data System (ADS)

    Saragaglia, A.; Fetita, C.; Preteux, F.; Brillet, P. Y.; Grenier, P. A.

    2005-08-01

    The assessment of bronchial reactivity and wall remodeling in asthma plays a crucial role in better understanding such a disease and evaluating therapeutic responses. Today, multi-detector computed tomography (MDCT) makes it possible to perform an accurate estimation of bronchial parameters (lumen and wall areas) by allowing a quantitative analysis in a cross-section plane orthogonal to the bronchus axis. This paper provides the tools for such an analysis by developing a 3D investigation method which relies on 3D reconstruction of bronchial lumen and central axis computation. Cross-section images at bronchial locations interactively selected along the central axis are generated at appropriate spatial resolution. An automated approach is then developed for accurately segmenting the inner and outer bronchi contours on the cross-section images. It combines mathematical morphology operators, such as "connection cost", and energy-controlled propagation in order to overcome the difficulties raised by vessel adjacencies and wall irregularities. The segmentation accuracy was validated with respect to a 3D mathematically-modeled phantom of a pair bronchus-vessel which mimics the characteristics of real data in terms of gray-level distribution, caliber and orientation. When applying the developed quantification approach to such a model with calibers ranging from 3 to 10 mm diameter, the lumen area relative errors varied from 3.7% to 0.15%, while the bronchus area was estimated with a relative error less than 5.1%.

  20. Shading correction for on-board cone-beam CT in radiation therapy using planning MDCT images.

    PubMed

    Niu, Tianye; Sun, Mingshan; Star-Lack, Josh; Gao, Hewei; Fan, Qiyong; Zhu, Lei

    2010-10-01

    Applications of cone-beam CT (CBCT) to image-guided radiationtherapy (IGRT) are hampered by shading artifacts in the reconstructed images. These artifacts are mainly due to scatter contamination in the projections but also can result from uncorrected beam hardening effects as well as nonlinearities in responses of the amorphous silicon flat panel detectors. While currently, CBCT is mainly used to provide patient geometry information for treatment setup, more demanding applications requiring high-quality CBCT images are under investigation. To tackle these challenges, many CBCT correction algorithms have been proposed; yet, a standard approach still remains unclear. In this work, we propose a shading correction method for CBCT that addresses artifacts from low-frequency projection errors. The method is consistent with the current workflow of radiation therapy. With much smaller inherent scatter signals and more accurate detectors, diagnostic multidetector CT (MDCT) provides high quality CT images that are routinely used for radiation treatment planning. Using the MDCT image as "free" prior information, we first estimate the primary projections in the CBCT scan via forward projection of the spatially registered MDCT data. Since most of the CBCT shading artifacts stem from low-frequency errors in the projections such as scatter, these errors can be accurately estimated by low-pass filtering the difference between the estimated and raw CBCT projections. The error estimates are then subtracted from the raw CBCT projections. Our method is distinct from other published correction methods that use the MDCT image as a prior because it is projection-based and uses limited patient anatomical information from the MDCT image. The merit of CBCT-based treatment monitoring is therefore retained. The proposed method is evaluated using two phantom studies on tabletop systems. On the Catphan 600 phantom, our approach reduces the reconstruction error from 348 Hounsfield unit (HU

  1. Shading correction for on-board cone-beam CT in radiation therapy using planning MDCT images

    SciTech Connect

    Niu Tianye; Sun, Mingshan; Star-Lack, Josh; Gao Hewei; Fan Qiyong; Zhu Lei

    2010-10-15

    Purpose: Applications of cone-beam CT (CBCT) to image-guided radiation therapy (IGRT) are hampered by shading artifacts in the reconstructed images. These artifacts are mainly due to scatter contamination in the projections but also can result from uncorrected beam hardening effects as well as nonlinearities in responses of the amorphous silicon flat panel detectors. While currently, CBCT is mainly used to provide patient geometry information for treatment setup, more demanding applications requiring high-quality CBCT images are under investigation. To tackle these challenges, many CBCT correction algorithms have been proposed; yet, a standard approach still remains unclear. In this work, we propose a shading correction method for CBCT that addresses artifacts from low-frequency projection errors. The method is consistent with the current workflow of radiation therapy. Methods: With much smaller inherent scatter signals and more accurate detectors, diagnostic multidetector CT (MDCT) provides high quality CT images that are routinely used for radiation treatment planning. Using the MDCT image as ''free'' prior information, we first estimate the primary projections in the CBCT scan via forward projection of the spatially registered MDCT data. Since most of the CBCT shading artifacts stem from low-frequency errors in the projections such as scatter, these errors can be accurately estimated by low-pass filtering the difference between the estimated and raw CBCT projections. The error estimates are then subtracted from the raw CBCT projections. Our method is distinct from other published correction methods that use the MDCT image as a prior because it is projection-based and uses limited patient anatomical information from the MDCT image. The merit of CBCT-based treatment monitoring is therefore retained. Results: The proposed method is evaluated using two phantom studies on tabletop systems. On the Catphan(c)600 phantom, our approach reduces the reconstruction error

  2. Four- and Eight-Channel Aortoiliac CT Angiography: A Comparative Study

    SciTech Connect

    Karcaaltincaba, Musturay Foley, Dennis

    2005-04-15

    Purpose. To compare performance parameters, contrast material load and radiation dose in a patient cohort having aortoiliac CT angiography using 4- and 8-channel multidetector CT (MDCT) systems. Methods. Eighteen patients with abdominal aortic aneurysms underwent initial 4-channel and follow-up 8-channel MDCT angiography. Both the 4- and 8-channel MDCT systems utilized a matrix detector of 16 x 1.25 mm rows. Scan coverage included the abdominal aorta and iliac arteries to the level of the proximal femoral arteries. For 4-channel MDCT, nominal slice thickness and beam pitch were 1.25 mm and 1.5, respectively, and for 8-channel MDCT they were 1.25 mm and 1.35 or 1.65 respectively. Scan duration, iodinated contrast material load and mean aortoiliac attenuation were compared retrospectively. Comparative radiation dose measurements for 4- and 8-channel MDCT were obtained using a multiple scan average dose technique on an abdominal phantom. Results. Compared with 4-channel MDCT, 8-channel MDCT aortoiliac angiography was performed with equivalent collimation, decreased contrast load (mean 45% decrease: 144 ml versus 83 ml of 300 mg iodine/ml contrast material) and decreased acquisition time (mean 51% shorter: 34.4 sec versus 16.9 sec) without a significant change in mean aortic enhancement (299 HU versus 300 HU, p > 0.05). Radiation dose was 2 rad for the 4-channel system and 2/1.5 rad for the 8-channel system at 1.35/1.65 pitch respectively. Conclusion. Compared with 4-channel MDCT, aortoiliac CT angiography with 8-channel MDCT produces equivalent z-axis resolution with decreased contrast load and acquisition time without increased radiation exposure.

  3. Comparing Simulations and Observations of Reionization-Epoch Galaxies

    NASA Astrophysics Data System (ADS)

    Dave, Romeel; Finlator, Kristian

    2006-05-01

    We propose to test and constrain models of early galaxy formation through comparisons with observations of reionization-epoch (z>6) galaxies observed using Spitzer. The goals are to (1) Make predictions for z>6 objects using state-of-the-art cosmological hydrodynamic simulations of galaxy formation tailored to study the reionization epoch; (2) Develop a publicly-available tool called SPOC designed to obtain detailed constraints on physical properties of observed galaxies through comparisons with simulated galaxy catalogs; and (3) Use SPOC to test and constrain models of galaxy formation through comparisons with rapidly- advancing observations in the new frontier of early universe studies. The results of this study will yield deeper insights into the galaxy formation process at these mostly unexplored epochs, with implications for understanding the formation of massive galaxies, studying the topology and evolution of IGM reionization, and designing future surveys to detect first objects. The SPOC tool will facilitate a closer connection between observations and theory by enabling the community to interpret data within the framework of current hierarchical structure formation models, in turn providing detailed tests of these models that is essential for driving the field forward.

  4. Accuracy of gantry rotation time of less than 300 ms for modern MDCT systems.

    PubMed

    Fukuda, Atsushi; Lin, Pei-Jan Paul; Matsubara, Kosuke; Miyati, Tosiaki

    2015-01-01

    The accuracy of gantry rotation times of less than 300 ms has been assessed for two "state-of-the art" MDCT systems. The rotation time was measured at selected nominal rotation times (275 and 280 ms) with a solid-state detector; Unfors Xi probe. The detector was positioned on the inner bottom of the gantry bore. Because a pair of two successive radiation peaks is necessary for determination of the rotation time, the radiation detection was performed with the helical scan mode of operation. Upon completion of the data acquisition, we determined the peak times with the Unfors Xi View software program to obtain the rotation time. The means and standard deviations of the measured rotation times were 275.3 ± 0.5 and 285.1 ± 0.4 ms, respectively. The inaccuracy of the rotation time was approximately 5 ms at most, which was comparable to that previously reported for slower rotation times.

  5. Understanding Small Solar Magnetic Elements: Comparing Models and Observations

    NASA Astrophysics Data System (ADS)

    Leka, K. D.; Steiner, O.; Grossmann-Doerth, U.

    1999-05-01

    We perform direct comparisons of high-resolution spectropolarimetric observations with a full MHD model of the magnetized solar atmosphere. In this manner we investigate the evolution and dynamics of small magnetic elements by fully utilizing the diagnostics available with Stokes spectropolarimetry, both computed and observed. The model is a 2-D time-dependent numerical simulation of a small (~ 600 km diameter) magnetic feature embedded in a non-magnetized atmosphere (Steiner et al., 1998). At select time-steps, synthetic emergent Stokes I and V profiles are computed using a polarized radiation transfer code. The data consist of Stokes I and V spectra from the Advanced Stokes Polarimeter for seventeen small magnetic elements located near disk-center. For both the observed and computed Stokes spectra, diagnostics are computed including the emergent continuum intensity, V-crossing shift, and amplitude and area asymmetries of the V-profile. We find that it is possible to differentiate between salient processes occurring in the magnetic atmosphere (strong flows, gradients, etc.) by their spectropolarimetric signature; from this, we determine the dominant processes present in the observed magnetic structures. The results are extremely encouraging. We find good qualitative agreement between the amplitude and area asymmetries and their spatial variation. Quantitatively, the agreement is surprisingly good in many cases. While limitations exist for both the model and observations, this stringent test allows us to comment on the dynamics and possible evolutionary differences present in the observed magnetic features. This work is funded in part by NSF grant ATM-9710782. Reference: - Steiner, O., Grossmann-Doerth, U., Knolker, M., Schussler, M.: 1998, ApJ 495, 468

  6. Robust extraction of the aorta and pulmonary artery from 3D MDCT image data

    NASA Astrophysics Data System (ADS)

    Taeprasartsit, Pinyo; Higgins, William E.

    2010-03-01

    Accurate definition of the aorta and pulmonary artery from three-dimensional (3D) multi-detector CT (MDCT) images is important for pulmonary applications. This work presents robust methods for defining the aorta and pulmonary artery in the central chest. The methods work on both contrast enhanced and no-contrast 3D MDCT image data. The automatic methods use a common approach employing model fitting and selection and adaptive refinement. During the occasional event that more precise vascular extraction is desired or the method fails, we also have an alternate semi-automatic fail-safe method. The semi-automatic method extracts the vasculature by extending the medial axes into a user-guided direction. A ground-truth study over a series of 40 human 3D MDCT images demonstrates the efficacy, accuracy, robustness, and efficiency of the methods.

  7. Tools of the trade for CTA: MDCT scanners and contrast medium injection protocols.

    PubMed

    Hallett, Richard L; Fleischmann, Dominik

    2006-12-01

    The introduction of multi-detector row computed tomography (MDCT) scanners in 1998 ushered in new advances in CT angiography (CTA). The subsequent expansion of MDCT scanner capabilities, coupled with advances in understanding of contrast medium (CM) dynamics, has further improved the clinical availability and consistency of CTA. We will review recent advances in CT scanner technology and discuss early CM dynamics. Specifically, we describe an approach tailored to the available scanner technology and to patient size aimed at providing consistently robust CTA studies across all vascular territories. A rational method to design combined CTA scan/injection protocols to facilitate this goal will be described. Our current experience with a simplified protocol for CTA with 64-MDCT will also be explained.

  8. Radiation dose reduction to the male gonads during MDCT: the effectiveness of a lead shield.

    PubMed

    Hohl, Christian; Mahnken, Andreas H; Klotz, Ernst; Das, Marco; Stargardt, Achim; Mühlenbruch, Georg; Schmidt, Thorsten; Günther, Rolf W; Wildberger, Joachim E

    2005-01-01

    Our study was designed to quantify the effect of a standard gonad shield on the testicular radiation exposure due to scatter during routine abdominopelvic MDCT. Routine abdominopelvic MDCT was performed in 34 patients with gonadal lead shielding and 32 patients without this shielding; the testes were not exposed to the direct beam during the examination. We estimated the testicular dose administered with thermoluminescent dosimetry, taking into account each patient's body weight and body mass index (BMI). With a 1-mm lead shield, the mean testicular dose was reduced from 2.40 to 0.32 mSv, a reduction of 87%. The difference was found to be statistically significant (p < 0.0001). No correlation between testicular dose and body weight or BMI was found. Shielding the male gonads reduces the testicular radiation dose during abdominopelvic MDCT significantly and can be recommended for routine use.

  9. Aortic and hepatic contrast enhancement with abdominal 64-MDCT in pediatric patients: effect of body weight and iodine dose.

    PubMed

    Bae, Kyongtae T; Shah, Amisha J; Shang, Sherry S; Wang, Jin Hong; Chang, Samuel; Kanematsu, Masayuki; Hildebolt, Charles F

    2008-11-01

    The purpose of our study was to retrospectively evaluate the effect of body weight and iodine dose on aortic and hepatic contrast enhancement in pediatric patients who underwent 64-MDCT of the abdomen and pelvis. Eighty-seven consecutive pediatric patients (50 boys and 37 girls; median age, 12.1 years; age range, 3.8-17.6 years) underwent standard abdominopelvic CT with a 64-MDCT scanner. Contrast medium (350 mg I/mL) was injected using a power injector at 2 mL/s followed by 15-20 mL of saline flush. According to our CT protocol, the volume of administered contrast medium was approximately 1.8 mL/kg of body weight, up to the maximum volume of 80 mL. CT scanning was initiated 60 seconds after the start of the contrast medium injection. CT attenuations of the aorta and liver were measured. For each patient, the injected contrast medium iodine mass per body weight index (g I/kg) (hereafter, iodine mass body index) was calculated. Linear regression analysis was performed between iodine mass body index and aortic and hepatic attenuations. A wide range of patient weights (19-82 kg; mean, 48.6 kg [95% CI, 45.3-51.9 kg]) and contrast volumes (30-80 mL; median, 80.0 mL) were observed. The median attenuations were 149.0 HU (141.0-160.0 HU) for the aorta and 113.5 HU (109.5-120.0 HU) for the liver. Moderately high correlations were observed between iodine mass body index and aortic (Spearman's rho [r(s)] = 0.60 [0.45-0.72]; p < 0.001) and hepatic (r(s) = 0.60 [0.42-0.70]; p < 0.001) attenuations. The regression formulae for aortic attenuation (58.4 + 176.3 x iodine mass body index [p < 0.001]) and hepatic attenuation (58.7 + 108.5 x iodine mass body index [p < 0.001]) indicate that 1.5 and 1.8 mL/kg (350 mg I/mL) of contrast media are required to achieve 116 and 127 HU, respectively, of contrast-enhanced attenuation in the liver. In our study, using abdominal 64-MDCT in pediatric patients, we found that approximately 1.5 mL/kg, or 0.525 g I/kg, yields 116 HU of hepatic

  10. Arteriovenous fistula and graft evaluation in hemodialysis patients using MDCT: a primer.

    PubMed

    Chen, Min-Chi; Tsai, Wei-Lin; Tsai, I-Chen; Chan, Si-Wa; Liao, Wan-Chun; Lin, Pao-Chun; Yang, Su Jing

    2010-03-01

    Patent arteriovenous fistula (AVF) is related to better prognosis and quality of life for patients on long-term dialysis. When AVF dysfunction is suspected, MDCT is a good noninvasive tool for evaluating the entire AVF structure and determining reversible conditions for treatment. The aim of this article is to introduce the scanning and interpretation techniques and to illustrate the conditions related to early and late fistula failures. MDCT is a fast, noninvasive, and accurate technique for diagnosing AVF complications. Radiologists familiar with these techniques can help to improve the prognosis and quality of life for hemodialysis patients.

  11. Comparing probability distributions for the World's Maximum Observed Floods

    NASA Astrophysics Data System (ADS)

    Markopoulos, Apostolos; Dimitriadis, Panayiotis; Koutsoyiannis, Demetris

    2017-04-01

    A database of annual maximum daily river discharges extracted from the Catalogue of World's Maximum Observed Floods (International Association of Hydrological Sciences) is analyzed.Several probability distributions are tested against each other in terms of the goodness of fit, in order to identify whether a single distribution can adequately describe all time series in spite of the various climatic regimes, location and geomorphologic conditions. The analysis is relevant to the ongoing and intensifying discussion about climate variability and the intensity of extreme phenomena such as river discharges.

  12. A new approach to the assessment of lumen visibility of coronary artery stent at various heart rates using 64-slice MDCT

    PubMed Central

    Groen, J. M.; van Ooijen, P. M. A.; Oudkerk, M.

    2007-01-01

    Coronary artery stent lumen visibility was assessed as a function of cardiac movement and temporal resolution with an automated objective method using an anthropomorphic moving heart phantom. Nine different coronary stents filled with contrast fluid and surrounded by fat were scanned using 64-slice multi-detector computed tomography (MDCT) at 50–100 beats/min with the moving heart phantom. Image quality was assessed by measuring in-stent CT attenuation and by a dedicated tool in the longitudinal and axial plane. Images were scored by CT attenuation and lumen visibility and compared with theoretical scoring to analyse the effect of multi-segment reconstruction (MSR). An average increase in CT attenuation of 144 ± 59 HU and average diminished lumen visibility of 29 ± 12% was observed at higher heart rates in both planes. A negative correlation between image quality and heart rate was non-significant for the majority of measurements (P > 0.06). No improvement of image quality was observed in using MSR. In conclusion, in-stent CT attenuation increases and lumen visibility decreases at increasing heart rate. Results obtained with the automated tool show similar behaviour compared with attenuation measurements. Cardiac movement during data acquisition causes approximately twice as much blurring compared with the influence of temporal resolution on image quality. Electronic supplementary material The online version of this article (doi:10.1007/s00330-007-0568-8) contains supplementary material, which is available to authorized users. PMID:17429648

  13. 3-T contrast-enhanced MR angiography in evaluation of suspected intracranial aneurysm: comparison with MDCT angiography.

    PubMed

    Nael, Kambiz; Villablanca, J Pablo; Mossaz, Léonard; Pope, Whitney; Juncosa, Alex; Laub, Gerhard; Finn, J Paul

    2008-02-01

    The purpose of this study was to prospectively evaluate a high-spatial-resolution contrast-enhanced 3-T MR angiography protocol for detection and characterization of intracranial aneurysms and to compare the results with those of MDCT angiography. Forty-one patients with suspected intracranial aneurysm underwent high-spatial-resolution 3D contrast-enhanced MR angiography and CT angiography (CTA). With a generalized autocalibrating partially parallel acquisition algorithm with an acceleration factor of 4 at 3 T, contrast-enhanced MR angiographic images were acquired over 20 seconds with a spatial-resolution of 0.7 x 0.7 x 0.8 mm. CTA images were acquired with a spatial resolution of 0.35 x 0.35 x 0.8 mm on a 16-MDCT scanner in 17 seconds. The images from the two studies were evaluated independently by two neuroradiologists for image quality, presence of aneurysm, and characterization of aneurysm. The dimensions of the aneurysm were measured independently with both techniques. A total of 25 aneurysms were identified with both contrast-enhanced MR angiography and CTA. A comparative analysis of detection and depiction of aneurysms showed excellent interobserver agreement for both contrast-enhanced MR angiography (kappa = 0.81) and CTA (kappa = 0.91) images. There was significant correlation between the techniques for both qualitative assessment of aneurysm depiction (rho = 0.92; 95% CI, 0.88-0.95) and quantitative dimensional measurement of aneurysm size (r = 0.94; 95% CI, 0.92-0.97). Contrast-enhanced MR angiography at 3 T is reliable for evaluation and characterization of intracranial aneurysms. The results are comparable with those of MDCTA.

  14. Whistler Observations on DEMETER Compared with FWM Numerical Simulations

    NASA Astrophysics Data System (ADS)

    Compston, A. J.; Cohen, M.; Lehtinen, N. G.; Inan, U.; Linscott, I.; Parrot, M.

    2012-12-01

    Terrestrial Very Low Frequency (VLF) electromagnetic radiation, which plays an important role in the Van Allen radiation belts, is injected into Earth's plasmasphere from two primary sources: man-made VLF transmitters and lightning discharges. Recent studies have called into question some of the numerical models that simulate radiation injection into the plasmasphere by VLF transmitters: specifically, said models have been shown to overestimate the electromagnetic fields by at least 10 dB when compared to satellite measurements. In this study, we compared lightning-induced whistlers on the low earth orbiting DEMETER satellite with an electromagnetic, frequency domain Full Wave Method (FWM) finite element numerical code. By correlating lightning discharge time, location, and peak current data from the National Lightning Detection Network (NLDN) in the United States with burst mode electromagnetic field measurements of the whistlers on DEMETER, we were able to make an accurate estimate of the field strengths on DEMETER from the FWM simulation results for over 5000 lightning discharges over more than 10 different DEMETER passes during both the day and night. The FWM field estimates match the DEMETER measurements to less than 5 dB.

  15. Pelvic ultrasound immediately following MDCT in female patients with abdominal/pelvic pain: is it always necessary?

    PubMed

    Yitta, Silaja; Mausner, Elizabeth V; Kim, Alice; Kim, Danny; Babb, James S; Hecht, Elizabeth M; Bennett, Genevieve L

    2011-10-01

    To determine the added value of reimaging the female pelvis with ultrasound (US) immediately following multidetector CT (MDCT) in the emergent setting. CT and US exams of 70 patients who underwent MDCT for evaluation of abdominal/pelvic pain followed by pelvic ultrasound within 48 h were retrospectively reviewed by three readers. Initially, only the CT images were reviewed followed by evaluation of CT images in conjunction with US images. Diagnostic confidence was recorded for each reading and an exact Wilcoxon signed rank test was performed to compare the two. Changes in diagnosis based on combined CT and US readings versus CT readings alone were identified. Confidence intervals (95%) were derived for the percentage of times US reimaging can be expected to lead to a change in diagnosis relative to the diagnosis based on CT interpretation alone. Ultrasound changed the diagnosis for the ovaries/adnexa 8.1% of the time (three reader average); the majority being cases of a suspected CT abnormality found to be normal on US. Ultrasound changed the diagnosis for the uterus 11.9% of the time (three reader average); the majority related to the endometrial canal. The 95% confidence intervals for the ovaries/adnexa and uterus were 5-12.5% and 8-17%, respectively. Ten cases of a normal CT were followed by a normal US with 100% agreement across all three readers. Experienced readers correctly diagnosed ruptured ovarian cysts and tubo-ovarian abscesses (TOA) based on CT alone with 100% agreement. US reimaging after MDCT of the abdomen and pelvis is not helpful: (1) following a normal CT of the pelvic organs or (2) when CT findings are diagnostic and/or characteristic of certain entities such as ruptured cysts and TOA. Reimaging with ultrasound is warranted for (1) less-experienced readers to improve diagnostic confidence or when CT findings are not definitive, (2) further evaluation of suspected endometrial abnormalities. A distinction should be made between the need for

  16. Case B binary evolution compared to observed Algols

    NASA Astrophysics Data System (ADS)

    van Rensbergen, Walter

    We follow the path in the HR-diagram of binaries with a B-type primary at birth which form an Algol system during case B mass transfer. Our calculations were done with and without the assumption of conservative mass transfer, giving very different results for the distributions of mass ratios and orbital periods for the obtained Algols. The conservative model fits the observations poorly by producing far too many Algols with low mass ratios and large orbital periods. Liberal models yield better agreement between theory and obervations. The best agreement is obtained when ≍50% of the mass lost by the primary is trapped into a ring with radius ≍2.5 × the semi major axis of the binary orbit.

  17. Comparative observations of plasma waves at the outer planets

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.

    1992-01-01

    Observations of the plasma-wave spectra from the four major outer planets are examined with particular attention given to the instabilities related to the precipitation of energetic particles. Wave-particle interactions involving hiss, chorus, and electron-cyclotron harmonic emissions are studied. These interactions contribute about 10 exp 13 W into the Jovian atmosphere, and the electron-cyclotron emissions on Saturn are shown to contribute significantly to the precipitation of energetic electrons. Whistler-mode waves are shown to exist at Uranus with intensities that could put 3-40 keV electrons on strong diffusion, but the amplitudes of the emissions are not sufficient to make them a significant part of precipitation. Weak electron-cyclotron harmonic emissions and whistler modes are detected at Neptune, suggesting that the present dataset is based on regions of low wave intensities.

  18. Comparing Observed Hurricane Conditions Against Potential Future Climate Change Influences

    NASA Astrophysics Data System (ADS)

    Graham, W. D.

    2012-12-01

    Climate Adaptation Science Investigators: (CASI) is to advance and apply NASA's scientific expertise and products to develop climate adaptation strategies that support NASA's overall mission by minimizing risks to each center's operations, physical assets, and personnel. Using Hurricane Katrina observations as a baseline, we use ADCIRC to model surge extent with simple modifications of the storm track. We examine two time now (T0) scenarios of present-day climatological factors: 1) translating the 2005 path 7 km west; and 2) rotating the approach angle from due-north to WNW. Second, we examine two future time scenarios (TX) by infusing climate change conditions, such as sea level rise and increased storm intensity, into a T0 baseline to assess future impacts. The primary goal of this work entails planning and protecting NASA assets and infrastructure. The adjacent communities, state and local emergency managers, gain benefit from this NASA work as data and analysis includes the surrounding geography.

  19. Comparing remote-sensing observations of aerosols and clouds

    NASA Astrophysics Data System (ADS)

    Spencer, R. S.; Levy, R. C.; Mattoo, S.; Kleidman, R. G.; Yorks, J. E.

    2016-12-01

    The interaction of clouds and aerosols is one of the least well-understood phenomena affecting climate change, atmospheric dynamics and weather. The Dark Target (DT) satellite retrieval algorithm provides a 10 km aerosol product from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on Terra and Aqua. This geospatial product provides daily coverage of the global distribution of aerosol optical depth (AOD). The coarse resolution leaves us with significant uncertainty in quantifying aerosol-cloud interactions, requiring us to use higher resolution data to improve our understanding. The DT algorithm was applied to high-resolution enhanced-MODIS Airborne Simulator (eMAS) data obtained during the "Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign over the U.S. in 2013. The instrument was deployed on the ER-2 high-altitude aircraft along side the Cloud Physics Lidar (CPL), which took vertical profiles along the eMAS swath centerline. We identified 53 collocations with eMAS over ground-based AERONET sunphotometer sites, and found that eMAS AOD was biased by a factor of 2. When eMAS was far from clouds, and the AOD was low, there was little bias. However, in moderate or high aerosol regimes, eMAS retrieved rings of enhanced AOD around some of the identified clouds. Can we validate these rings of enhanced AOD? A cloud-distance layer was created for eMAS to study these areas and determine which cloud conditions might be correlated with them. In most cases, the AOD measurements converged to a clear sky value with increasing distance from cloud. Comparing these new values to Aeronet, the bias was reduced to a factor of 1.4. A cloud-direction layer was also created which revealed that within 5 km of clouds, there was generally a high bias on the sunward facing side of a cloud and low bias on the "shadow" side. Furthermore, there were many cases where the CPL indicated clouds that were not

  20. Interobserver agreement for detection of malignant features of intraductal papillary mucinous neoplasms of the pancreas on MDCT.

    PubMed

    Do, Richard K G; Katz, Seth S; Gollub, Marc J; Li, Jian; LaFemina, Jennifer; Zabor, Emily C; Moskowitz, Chaya S; Klimstra, David S; Allen, Peter J

    2014-11-01

    The purpose of this retrospective study was to measure interobserver agreement in the assessment of malignant imaging features of intraductal papillary mucinous neoplasms (IPMNs) on MDCT. Pancreatic protocol CT studies were reviewed for 84 patients with resected IPMNs. Maximal diameter of the dominant cyst, presence of a mural nodule, presence of a solid component, and diameters of the main pancreatic duct (MPD) and common bile duct (CBD) were measured by four radiologists independently. In each patient, the IPMN was classified into one of three types: main duct, branch duct, or mixed IPMN. Interobserver agreement of lesion features was examined using the intraclass correlation coefficient (ICC) for continuous features and Fleiss kappa for categorical features. The final dataset included 55 branch duct IPMNs, nine main duct IPMNs, and 20 mixed IPMNs. Moderate agreement (ĸ = 0.458; 95% CI, 0.345-0.564) was observed in assigning branch duct, main duct, or mixed IPMN subtypes. Measurement agreement was substantial to excellent for dominant cyst (ICC = 0.852; 95% CI, 0.777-0.907), MPD (0.753, 0.655-0.837), and CBD (0.608, 0.463-0.724) but only fair to moderate for the detection of the presence of mural nodule (ĸ = 0.284, 0.125-0.432) or solid component (ĸ = 0.405, 0211-0.577). Substantial to excellent interobserver agreement in the measurement of cyst diameter, MPD, and CBD support their use for characterizing malignant features of IPMN on MDCT. However, the subjective interpretation of the presence of solid components and mural nodules by individual radiologists was more variable.

  1. US and MDCT diagnosis of a rare cause of haematuria in children: Posterior nutcracker syndrome.

    PubMed

    Ozel, A; Tufaner, O; Kaya, E; Maldur, V

    2011-06-01

    Posterior nutcracker syndrome is caused by compression of the left renal vein between the abdominal aorta and the vertebral column. We present the case of a 14-year-old girl with vague left loin pain, mild haematuria and proteinuria. Diagnosis of this rare syndrome was achieved using color Doppler US and multidetector computed tomography (MDCT) angiography.

  2. Three-dimensional MDCT angiography of splanchnic arteries: pearls and pitfalls.

    PubMed

    Dohan, A; Dautry, R; Guerrache, Y; Fargeaudou, Y; Boudiaf, M; Le Dref, O; Sirol, M; Soyer, P

    2015-02-01

    Fast scanning along with high resolution of multidetector computed tomography (MDCT) have expanded the role of non-invasive imaging of splanchnic arteries. Advancements in both MDCT scanner technology and three-dimensional (3D) imaging software provide a unique opportunity for non-invasive investigation of splanchnic arteries. Although standard axial computed tomography (CT) images allow identification of splanchnic arteries, visualization of small or distal branches is often limited. Similarly, a comprehensive assessment of the complex anatomy of splanchnic arteries is often beyond the reach of axial images. However, the submillimeter collimation that can be achieved with MDCT scanners now allows the acquisition of true isotropic data so that a high spatial resolution is now maintained in any imaging plane and in 3D mode. This ability to visualize the complex network of splanchnic arteries using 3D rendering and multiplanar reconstruction is of major importance for an optimal analysis in many situations. The purpose of this review is to discuss and illustrate the role of 3D MDCT angiography in the detection and assessment of abnormalities of splanchnic arteries as well as the limitations of the different reconstruction techniques.

  3. MDCT quantification is the dominant parameter in decision-making regarding chest tube drainage for stable patients with traumatic pneumothorax.

    PubMed

    Cai, Wenli; Lee, June-Goo; Fikry, Karim; Yoshida, Hiroyuki; Novelline, Robert; de Moya, Marc

    2012-07-01

    It is commonly believed that the size of a pneumothorax is an important determinant of treatment decision, in particular regarding whether chest tube drainage (CTD) is required. However, the volumetric quantification of pneumothoraces has not routinely been performed in clinics. In this paper, we introduced an automated computer-aided volumetry (CAV) scheme for quantification of volume of pneumothoraces in chest multi-detect CT (MDCT) images. Moreover, we investigated the impact of accurate volume of pneumothoraces in the improvement of the performance in decision-making regarding CTD in the management of traumatic pneumothoraces. For this purpose, an occurrence frequency map was calculated for quantitative analysis of the importance of each clinical parameter in the decision-making regarding CTD by a computer simulation of decision-making using a genetic algorithm (GA) and a support vector machine (SVM). A total of 14 clinical parameters, including volume of pneumothorax calculated by our CAV scheme, was collected as parameters available for decision-making. The results showed that volume was the dominant parameter in decision-making regarding CTD, with an occurrence frequency value of 1.00. The results also indicated that the inclusion of volume provided the best performance that was statistically significant compared to the other tests in which volume was excluded from the clinical parameters. This study provides the scientific evidence for the application of CAV scheme in MDCT volumetric quantification of pneumothoraces in the management of clinically stable chest trauma patients with traumatic pneumothorax. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Effects of computing parameters and measurement locations on the estimation of 3D NPS in non-stationary MDCT images.

    PubMed

    Miéville, Frédéric A; Bolard, Gregory; Bulling, Shelley; Gudinchet, François; Bochud, François O; Verdun, François R

    2013-11-01

    The goal of this study was to investigate the impact of computing parameters and the location of volumes of interest (VOI) on the calculation of 3D noise power spectrum (NPS) in order to determine an optimal set of computing parameters and propose a robust method for evaluating the noise properties of imaging systems. Noise stationarity in noise volumes acquired with a water phantom on a 128-MDCT and a 320-MDCT scanner were analyzed in the spatial domain in order to define locally stationary VOIs. The influence of the computing parameters in the 3D NPS measurement: the sampling distances bx,y,z and the VOI lengths Lx,y,z, the number of VOIs NVOI and the structured noise were investigated to minimize measurement errors. The effect of the VOI locations on the NPS was also investigated. Results showed that the noise (standard deviation) varies more in the r-direction (phantom radius) than z-direction plane. A 25 × 25 × 40 mm(3) VOI associated with DFOV = 200 mm (Lx,y,z = 64, bx,y = 0.391 mm with 512 × 512 matrix) and a first-order detrending method to reduce structured noise led to an accurate NPS estimation. NPS estimated from off centered small VOIs had a directional dependency contrary to NPS obtained from large VOIs located in the center of the volume or from small VOIs located on a concentric circle. This showed that the VOI size and location play a major role in the determination of NPS when images are not stationary. This study emphasizes the need for consistent measurement methods to assess and compare image quality in CT.

  5. Fish bone foreign bodies in the pharynx and upper esophagus: evaluation with 64-slice MDCT.

    PubMed

    Park, Soyeon; Choi, Dae Seob; Shin, Hwa Seon; Cho, Jae Min; Jeon, Kyung Nyeo; Bae, Kyung-Soo; Koh, Eun Ha; Park, Jung Je

    2014-02-01

    Fish bone (FB) is one of the common causes of foreign body impaction in the pharynx and esophagus. To investigate the efficacy of 64-slice multidetector computed tomography (MDCT) for the evaluation of pharynx and upper esophageal FB foreign bodies. Sixty-six patients with suspected FB foreign body ingestion were examined by plain radiography (n = 40) and unenhanced MDCT (n = 66). We analyzed the presence, location, size, shape, and lying position of the foreign bodies. On MDCT, 46 foreign bodies were detected. Among them, 45 were confirmed by endoscopy. The sensitivity of MDCT for the detection of foreign bodies was 100%, which was superior to that of the plain radiography (51.7%). The location of the foreign bodies was most common in the upper esophagus (n = 22, 47.8%), followed by pharyngoesophageal junction (n = 10, 21.7%), transjunctional (n = 7, 15.2%), hypopharynx (n = 5, 10.9%), and oropharynx (n = 2, 4.3%). Their longest length was 5.3-40.1 mm (mean, 21.3 mm). Thirty-three FBs (71.7%) were linear and 13 (28.3%) were flat in shape. They showed transverse (n = 23, 50.0%), parallel (n = 13, 28.3%), and oblique positions (n = 10, 21.7%) to the long axis of the pharynx and esophagus, respectively. MDCT is useful for the evaluation of the pharynx and upper esophageal FB foreign bodies.

  6. Semi-automatic central-chest lymph-node definition from 3D MDCT images

    NASA Astrophysics Data System (ADS)

    Lu, Kongkuo; Higgins, William E.

    2010-03-01

    Central-chest lymph nodes play a vital role in lung-cancer staging. The three-dimensional (3D) definition of lymph nodes from multidetector computed-tomography (MDCT) images, however, remains an open problem. This is because of the limitations in the MDCT imaging of soft-tissue structures and the complicated phenomena that influence the appearance of a lymph node in an MDCT image. In the past, we have made significant efforts toward developing (1) live-wire-based segmentation methods for defining 2D and 3D chest structures and (2) a computer-based system for automatic definition and interactive visualization of the Mountain central-chest lymph-node stations. Based on these works, we propose new single-click and single-section live-wire methods for segmenting central-chest lymph nodes. The single-click live wire only requires the user to select an object pixel on one 2D MDCT section and is designed for typical lymph nodes. The single-section live wire requires the user to process one selected 2D section using standard 2D live wire, but it is more robust. We applied these methods to the segmentation of 20 lymph nodes from two human MDCT chest scans (10 per scan) drawn from our ground-truth database. The single-click live wire segmented 75% of the selected nodes successfully and reproducibly, while the success rate for the single-section live wire was 85%. We are able to segment the remaining nodes, using our previously derived (but more interaction intense) 2D live-wire method incorporated in our lymph-node analysis system. Both proposed methods are reliable and applicable to a wide range of pulmonary lymph nodes.

  7. Comparative energetics of the observed and simulated global circulation during the special observing periods of FGGE

    NASA Technical Reports Server (NTRS)

    Kung, E. C.; Baker, W. E.

    1986-01-01

    Energetics of the observed and simulated global circulation are evaluated in the zonal spectral domain for the special observing periods of FGGE. The study utilizes GLA analyses of FGGE observational data and parallel simulation experiments. There are noticeable differences in energy transformations between the observation and simulation during SOP-1. These include the baroclinic conversion C(n) by the zonal mean motion and short-wave disturbances, and the nonlinear wave-wave interaction L(n) at the long and short waves. The energy transformations of the short-wave disturbances are much more intense in the simulated circulation than in the observation. However, good agreement is noted in the conversion and dissipation of kinetic energy in the large- and cyclone-wave range n = 1-10. Spectral distributions of global energy transformations at the long- and cyclone-wave range indicate that the SOP-2 simulation agrees more closely with the observed fields than the SOP-1 simulation. Other pertinent points of energetics diagnosis are also included in the discussion.

  8. Addressing Informatics Barriers to Conducting Observational Comparative Effectiveness Research: A Comparative Case Analysis

    ERIC Educational Resources Information Center

    Boone, Christopher P. D.

    2013-01-01

    Background: The U.S. health care system has been under immense scrutiny for ever-increasing costs and poor health outcomes for its patients. Comparative Effectiveness Research (CER) has emerged as a generally accepted practice by providers, policy makers, and scientists as an approach to identify the most clinical- and cost-effective interventions…

  9. Addressing Informatics Barriers to Conducting Observational Comparative Effectiveness Research: A Comparative Case Analysis

    ERIC Educational Resources Information Center

    Boone, Christopher P. D.

    2013-01-01

    Background: The U.S. health care system has been under immense scrutiny for ever-increasing costs and poor health outcomes for its patients. Comparative Effectiveness Research (CER) has emerged as a generally accepted practice by providers, policy makers, and scientists as an approach to identify the most clinical- and cost-effective interventions…

  10. MDCT in the assessment of laryngeal trauma: value of 2D multiplanar and 3D reconstructions.

    PubMed

    Becker, Minerva; Duboé, Pier-Olivier; Platon, Alexandra; Kohler, Romain; Tasu, Jean-Pierre; Becker, Christoph D; Poletti, Pierre-Alexandre

    2013-10-01

    The purpose of this study was to analyze fracture patterns and related effects of laryngeal trauma and to assess the value of 2D multiplanar reformation (MPR) and 3D reconstruction. Among 4222 consecutively registered trauma patients who underwent emergency MDCT, 38 patients had presented with laryngeal trauma. Axial, 2D MPR, 3D volume-rendered, and virtual endoscopic images were analyzed retrospectively by two blinded observers according to predefined criteria. Laryngeal fractures, soft-tissue injuries, and airway compromise were evaluated and correlated with clinical, endoscopic, surgical, and follow-up findings. Fifty-nine fractures (37 thyroid, 13 cricoid, nine arytenoid) were present in 38 patients. They were isolated in 21 (55%) patients. The other 17 (45%) patients had additional injuries to the neck, face, brain, chest, or abdomen. Laryngeal fractures were bilateral in 31 (82%) patients and were associated with hyoid bone fractures in nine (24%) patients. Arytenoid luxation was present in eight cartilages. Axial imaging missed 7 of 59 (12%) laryngeal fractures, six of eight (75%) arytenoid luxations, and four of nine (44%) hyoid bone fractures. Additional 2D MPR imaging missed 5 of 59 (8%) laryngeal fractures, five of eight (62.5%) arytenoid luxations, and two of nine (22%) hyoid bone fractures, whereas 3D volume-rendered images depicted them all. Virtual endoscopy and 3D volume rendering added diagnostic accuracy with respect to the length, width, shape, and spatial orientation of fractures in 22 of 38 (58%) patients; arytenoid luxation in six of eight (75%) luxations; and the evaluation of airway narrowing in 19 of 38 (50%) patients. Three-dimensional volume rendering was not of additional value in evaluation of the cricoid cartilage. The use of 2D MPR and 3D volume rendering with or without virtual endoscopy improved assessment of thyroid and hyoid bone fractures, arytenoid luxations, and laryngotracheal narrowing, providing helpful data for optimal

  11. Variability in brain treatment during mummification of royal Egyptians dated to the 18th-20th dynasties: MDCT findings correlated with the archaeologic literature.

    PubMed

    Saleem, Sahar N; Hawass, Zahi

    2013-04-01

    The objective of our study was to use MDCT to study brain treatment and removal (excerebration) as part of mummification of royal Egyptian mummies dated to the 18th to early 20th Dynasties and to correlate the imaging findings with the archaeologic literature. As part of an MDCT study of the Royal Ancient Egyptian Mummies Project, we analyzed CT images of the heads of 12 mummies dated to circa 1493-1156 BC (18th to early 20th Dynasties). We reconstructed and analyzed CT images for the presence of cranial defects, brain remnants, intracranial embalming materials, and nasal packs. We compared the CT findings of mummies dated to the 18th Dynasty with those dated to the 19th to early 20th Dynasties. The Akhenaten mummy was excluded because of extensive postmortem skull fractures. CT showed that no brain treatment was offered to three mummies (Thutmose I, II, and III) who dated to the early 18th Dynasty and was offered to the eight mummies who dated later. The route of excerebration was transnasal in eight mummies; an additional suspected route was via a parietal defect. CT showed variable appearances of the intracranial contents. There were larger volumes of cranial packs and more variability in the appearances of the cranial packs in the royal mummies dated to the 19th to 20th Dynasties than in those dated to the 18th Dynasty. MDCT shows variations in brain treatment during mummification of royal Egyptian mummies (18th-20th Dynasties). This study sets a template for future CT studies of the heads of ancient Egyptian mummies and focuses on the key elements of cranial mummification in this ancient era.

  12. Selection of peripheral intravenous catheters with 24-gauge side-holes versus those with 22-gauge end-hole for MDCT: A prospective randomized study.

    PubMed

    Tamura, Akio; Kato, Kenichi; Kamata, Masayoshi; Suzuki, Tomohiro; Suzuki, Michiko; Nakayama, Manabu; Tomabechi, Makiko; Nakasato, Tatsuhiko; Ehara, Shigeru

    2017-02-01

    To compare the 24-gauge side-holes catheter and conventional 22-gauge end-hole catheter in terms of safety, injection pressure, and contrast enhancement on multi-detector computed tomography (MDCT). In a randomized single-center study, 180 patients were randomized to either the 24-gauge side-holes catheter or the 22-gauge end-hole catheter groups. The primary endpoint was safety during intravenous administration of contrast material for MDCT, using a non-inferiority analysis (lower limit 95% CI greater than -10% non-inferiority margin for the group difference). The secondary endpoints were injection pressure and contrast enhancement. A total of 174 patients were analyzed for safety during intravenous contrast material administration for MDCT. The overall extravasation rate was 1.1% (2/174 patients); 1 (1.2%) minor episode occurred in the 24-gauge side-holes catheter group and 1 (1.1%) in the 22-gauge end-hole catheter group (difference: 0.1%, 95% CI: -3.17% to 3.28%, non-inferiority P=1). The mean maximum pressure was higher with the 24-gauge side-holes catheter than with the 22-gauge end-hole catheter (8.16±0.95kg/cm(2) vs. 4.79±0.63kg/cm(2), P<0.001). The mean contrast enhancement of the abdominal aorta, celiac artery, superior mesenteric artery, and pancreatic parenchyma in the two groups were not significantly different. In conclusion, our study showed that the 24-gauge side-holes catheter is safe and suitable for delivering iodine with a concentration of 300mg/mL at a flow-rate of 3mL/s, and it may contribute to the care of some patients, such as patients who have fragile and small veins. (Trial registration: UMIN000023727). Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  13. A multiscale MDCT image-based breathing lung model with time-varying regional ventilation

    SciTech Connect

    Yin, Youbing; Choi, Jiwoong; Hoffman, Eric A.; Tawhai, Merryn H.; Lin, Ching-Long

    2013-07-01

    A novel algorithm is presented that links local structural variables (regional ventilation and deforming central airways) to global function (total lung volume) in the lung over three imaged lung volumes, to derive a breathing lung model for computational fluid dynamics simulation. The algorithm constitutes the core of an integrative, image-based computational framework for subject-specific simulation of the breathing lung. For the first time, the algorithm is applied to three multi-detector row computed tomography (MDCT) volumetric lung images of the same individual. A key technique in linking global and local variables over multiple images is an in-house mass-preserving image registration method. Throughout breathing cycles, cubic interpolation is employed to ensure C{sub 1} continuity in constructing time-varying regional ventilation at the whole lung level, flow rate fractions exiting the terminal airways, and airway deformation. The imaged exit airway flow rate fractions are derived from regional ventilation with the aid of a three-dimensional (3D) and one-dimensional (1D) coupled airway tree that connects the airways to the alveolar tissue. An in-house parallel large-eddy simulation (LES) technique is adopted to capture turbulent-transitional-laminar flows in both normal and deep breathing conditions. The results obtained by the proposed algorithm when using three lung volume images are compared with those using only one or two volume images. The three-volume-based lung model produces physiologically-consistent time-varying pressure and ventilation distribution. The one-volume-based lung model under-predicts pressure drop and yields un-physiological lobar ventilation. The two-volume-based model can account for airway deformation and non-uniform regional ventilation to some extent, but does not capture the non-linear features of the lung.

  14. A multiscale MDCT image-based breathing lung model with time-varying regional ventilation

    NASA Astrophysics Data System (ADS)

    Yin, Youbing; Choi, Jiwoong; Hoffman, Eric A.; Tawhai, Merryn H.; Lin, Ching-Long

    2013-07-01

    A novel algorithm is presented that links local structural variables (regional ventilation and deforming central airways) to global function (total lung volume) in the lung over three imaged lung volumes, to derive a breathing lung model for computational fluid dynamics simulation. The algorithm constitutes the core of an integrative, image-based computational framework for subject-specific simulation of the breathing lung. For the first time, the algorithm is applied to three multi-detector row computed tomography (MDCT) volumetric lung images of the same individual. A key technique in linking global and local variables over multiple images is an in-house mass-preserving image registration method. Throughout breathing cycles, cubic interpolation is employed to ensure C1 continuity in constructing time-varying regional ventilation at the whole lung level, flow rate fractions exiting the terminal airways, and airway deformation. The imaged exit airway flow rate fractions are derived from regional ventilation with the aid of a three-dimensional (3D) and one-dimensional (1D) coupled airway tree that connects the airways to the alveolar tissue. An in-house parallel large-eddy simulation (LES) technique is adopted to capture turbulent-transitional-laminar flows in both normal and deep breathing conditions. The results obtained by the proposed algorithm when using three lung volume images are compared with those using only one or two volume images. The three-volume-based lung model produces physiologically-consistent time-varying pressure and ventilation distribution. The one-volume-based lung model under-predicts pressure drop and yields un-physiological lobar ventilation. The two-volume-based model can account for airway deformation and non-uniform regional ventilation to some extent, but does not capture the non-linear features of the lung.

  15. Intussusception in Adults: The Role of MDCT in the Identification of the Site and Cause of Obstruction

    PubMed Central

    Valentini, Viola; Buquicchio, Grazia Loretta; Galluzzo, Michele; Ianniello, Stefania; Di Grezia, Graziella; Ambrosio, Rosa; Trinci, Margherita; Miele, Vittorio

    2016-01-01

    Unlike pediatric intussusception, intestinal intussusception is infrequent in adults and it is often secondary to a pathological condition. The growing use of Multi-Detector Computed Tomography (MDCT) in abdominal imaging has increased the number of radiological diagnoses of intussusception, even in transient and nonobstructing cases. MDCT is well suited to delineate the presence of the disease and provides valuable information about several features, such as the site of intussusception, the intestinal segments involved, and the extent of the intussuscepted bowel. Moreover, MDCT can demonstrate the complications of intussusceptions, represented by bowel wall ischemia and perforation, which are mandatory to promptly refer for surgery. However, not all intussusceptions need an operative treatment. In this paper, we review the current role of MDCT in the diagnosis and management of intussusception in adults, focusing on features, as the presence of a leading point, that may guide an accurate selection of patients for surgery. PMID:26819606

  16. In-Vivo Assessment of Femoral Bone Strength Using Finite Element Analysis (FEA) Based on Routine MDCT Imaging: A Preliminary Study on Patients with Vertebral Fractures

    PubMed Central

    Liebl, Hans; Garcia, Eduardo Grande; Holzner, Fabian; Noel, Peter B.; Burgkart, Rainer; Rummeny, Ernst J.; Baum, Thomas; Bauer, Jan S.

    2015-01-01

    Purpose To experimentally validate a non-linear finite element analysis (FEA) modeling approach assessing in-vitro fracture risk at the proximal femur and to transfer the method to standard in-vivo multi-detector computed tomography (MDCT) data of the hip aiming to predict additional hip fracture risk in subjects with and without osteoporosis associated vertebral fractures using bone mineral density (BMD) measurements as gold standard. Methods One fresh-frozen human femur specimen was mechanically tested and fractured simulating stance and clinically relevant fall loading configurations to the hip. After experimental in-vitro validation, the FEA simulation protocol was transferred to standard contrast-enhanced in-vivo MDCT images to calculate individual hip fracture risk each for 4 subjects with and without a history of osteoporotic vertebral fractures matched by age and gender. In addition, FEA based risk factor calculations were compared to manual femoral BMD measurements of all subjects. Results In-vitro simulations showed good correlation with the experimentally measured strains both in stance (R2 = 0.963) and fall configuration (R2 = 0.976). The simulated maximum stress overestimated the experimental failure load (4743 N) by 14.7% (5440 N) while the simulated maximum strain overestimated by 4.7% (4968 N). The simulated failed elements coincided precisely with the experimentally determined fracture locations. BMD measurements in subjects with a history of osteoporotic vertebral fractures did not differ significantly from subjects without fragility fractures (femoral head: p = 0.989; femoral neck: p = 0.366), but showed higher FEA based risk factors for additional incident hip fractures (p = 0.028). Conclusion FEA simulations were successfully validated by elastic and destructive in-vitro experiments. In the subsequent in-vivo analyses, MDCT based FEA based risk factor differences for additional hip fractures were not mirrored by according BMD measurements. Our

  17. Trabecular bone structure analysis in the osteoporotic spine using a clinical in vivo setup for 64-slice MDCT imaging: comparison to microCT imaging and microFE modeling.

    PubMed

    Issever, Ahi S; Link, Thomas M; Kentenich, Marie; Rogalla, Patrik; Schwieger, Karsten; Huber, Markus B; Burghardt, Andrew J; Majumdar, Sharmila; Diederichs, Gerd

    2009-09-01

    Assessment of trabecular microarchitecture may improve estimation of biomechanical strength, but visualization of trabecular bone structure in vivo is challenging. We tested the feasibility of assessing trabecular microarchitecture in the spine using multidetector CT (MDCT) on intact human cadavers in an experimental in vivo-like setup. BMD, bone structure (e.g., bone volume/total volume = BV/TV; trabecular thickness = Tb.Th; structure model index = SMI) and bone texture parameters were evaluated in 45 lumbar vertebral bodies using MDCT (mean in-plane pixel size, 274 microm(2); slice thickness, 500 microm). These measures were correlated with structure measures assessed with microCT at an isotropic spatial resolution of 16 microm and to microfinite element models (microFE) of apparent modulus and stiffness. MDCT-derived BMD and structure measures showed significant correlations to the density and structure obtained by microCT (BMD, R(2) = 0.86, p < 0.0001; BV/TV, R(2) = 0.64, p < 0.0001; Tb.Th, R(2) = 0.36, p < 0.01). When comparing microCT-derived measures with microFE models, the following correlations (p < 0.001) were found for apparent modulus and stiffness, respectively: BMD (R(2) = 0.58 and 0.66), BV/TV (R(2) = 0.44 and 0.58), and SMI (R(2) = 0.44 and 0.49). However, the overall highest correlation (p < 0.001) with microFE app. modulus (R(2) = 0.75) and stiffness (R(2) = 0.76) was achieved by the combination of QCT-derived BMD with the bone texture measure Minkowski Dimension. In summary, although still limited by its spatial resolution, trabecular bone structure assessment using MDCT is overall feasible. However, when comparing with microFE-derived bone properties, BMD is superior compared with single parameters for microarchitecture, and correlations further improve when combining with texture measures.

  18. Spectrum of MDCT Findings in Bowel Obstruction in a Tertiary Care Rural Hospital in Northern India

    PubMed Central

    Gupta, Ranjana; Mittal, Amit; Gupta, Sharad; Mittal, Kapish; Taneja, Arpit

    2016-01-01

    Introduction Multidetector Computed Tomography (MDCT) provides clinically and surgically important information in bowel obstruction. It can depict the severity, level and cause of obstruction. Aim To depict the spectrum of MDCT findings in cases of small and large bowel obstruction. Materials and Methods Contrast enhanced MDCT examination of 50 patients were retrospectively included in the study who had evidence of clinical as well as MDCT evidence of bowel obstruction and in whom surgical/clinical follow-up for final diagnosis was available. CT scan was done in all the patients with Ingenuity CT (128 slice MDCT, Philips Medical Systems). The axial sections were reconstructed in coronal and sagital planes to determine site and cause of bowel obstruction. Results There were 34 males and 16 females patients in this study with mean age of 28.4 years. The level of obstruction was in small bowel in 39 patients (76.67%) and large bowel in 11 patients (23.33%). Adhesive bands were the cause of Small Bowel Obstruction (SBO) in 17 patients (43.5% of SBO patients). The most common CT signs in adhesive band SBO were beak sign (seen in 70.6% patients) and fat notch sign (52.9% patients). Five cases of SBO were secondary to benign stricture. Matted adhesions were the cause of obstruction in 3 patients. All these patients showed transition zone in pelvis with positive small bowel faeces sign. Two patients with SBO due to adhesive band had evidence of closed loop obstruction with evidence of gangrenous gut on surgery. Large Bowel Obstruction (LBO) was seen in 11 patients. Most common cause of LBO was primary colonic malignancy, accounting for 7 patients (63.6%). In one patient, the cause was direct invasion of hepatic flexure by carcinoma of gall bladder. Other causes of LBO were pelvic adhesions, faecal impaction and ischaemic stricture. Conclusion SBO is more common than LBO with adhesive bands being the most common cause of SBO. MDCT is very useful for depicting site and cause

  19. Ectopia cordis with tetralogy of Fallot in an infant with pentalogy of Cantrell: high-pitch MDCT exam.

    PubMed

    Santiago-Herrera, Rogerio; Ramirez-Carmona, Rocio; Criales-Vera, Sergio; Calderon-Colmenero, Juan; Kimura-Hayama, Eric

    2011-07-01

    We report the MDCT findings of a 17-month-old girl with Cantrell's pentalogy, a rare congenital disease characterized by several defects in the ventral thoracoabdominal wall including ectopia cordis, and, in this patient, associated with tetralogy of Fallot. This case provides an example of the utility of a wide volume in coverage and high-pitch MDCT scan in the evaluation of complex cardiovascular anatomy in infants with congenital heart disease without the need of an ECG-gating acquisition.

  20. Does Computed Tomography Change our Observation and Management of Fracture Non-Unions?

    PubMed Central

    Kleinlugtenbelt, Ydo V.; Scholtes, Vanessa A.B.; Toor, Jay; Amaechi, Christian; Maas, Mario; Bhandari, Mohit; Poolman, Rudolf W.; Kloen, Peter

    2016-01-01

    Background: The purpose of this study was to determine whether Multi-Detector Computed Tomography (MDCT) in addition to plain radiographs influences radiologists’ and orthopedic surgeons’ diagnosis and treatment plans for delayed unions and non-unions. Methods: A retrospective database of 32 non-unions was reviewed by 20 observers. On a scale of 1 to 5, observers rated on X-Ray and a subsequent Multi Detector Helical Computer Tomography (MDCT) scan was performed to determine the following categories: “healed”, “bridging callus present”, “persistent fracture line” or “surgery advised”. Interobserver reliability in each category was calculated using the Interclass Correlation Coefficient (ICC). The influence of the MDCT scan on the raters’ observations was determined in each case by subtracting the two scores of both time points. Results: All four categories show fair interobserver reliability when using plain radiographs. MDCT showed no improvement, the reliability was poor for the categories “bridging callus present” and “persistent fracture line”, and fair for “healed” and “surgery advised”. In none of the cases, MDCT led to a change of management from nonoperative to operative treatment or vice versa. For 18 out of 32 cases, the treatment plans did not alter. In seven cases MDCT led to operative treatment while on X-ray the treatment plan was undecided. Conclusion: In this study, the interobserver reliability of MDCT scan is not greater than conventional radiographs for determining non-union. However, a MDCT scan did lead to a more invasive approach in equivocal cases. Therefore a MDCT is only recommended for making treatment strategies in those cases. PMID:27847846

  1. Image quality improvement in MDCT cardiac imaging via SMART-RECON method

    NASA Astrophysics Data System (ADS)

    Li, Yinsheng; Cao, Ximiao; Xing, Zhanfeng; Sun, Xuguang; Hsieh, Jiang; Chen, Guang-Hong

    2017-03-01

    Coronary CT angiography (CCTA) is a challenging imaging task currently limited by the achievable temporal resolution of modern Multi-Detector CT (MDCT) scanners. In this paper, the recently proposed SMARTRECON method has been applied in MDCT-based CCTA imaging to improve the image quality without any prior knowledge of cardiac motion. After the prospective ECG-gated data acquisition from a short-scan angular span, the acquired data were sorted into several sub-sectors of view angles; each corresponds to a 1/4th of the short-scan angular range. Information of the cardiac motion was thus encoded into the data in each view angle sub-sector. The SMART-RECON algorithm was then applied to jointly reconstruct several image volumes, each of which is temporally consistent with the data acquired in the corresponding view angle sub-sector. Extensive numerical simulations were performed to validate the proposed technique and investigate the performance dependence.

  2. State-of-the-art preoperative staging of gastric cancer by MDCT and magnetic resonance imaging

    PubMed Central

    Choi, Joon-Il; Joo, Ijin; Lee, Jeong Min

    2014-01-01

    Gastric cancer is one of the most common and fatal cancers. The importance of accurate staging for gastric cancer has become more critical due to the recent introduction of less invasive treatment options, such as endoscopic mucosal resection or laparoscopic surgery. The tumor-node-metastasis staging system is the generally accepted staging system for predicting the prognosis of patients with gastric cancer. Multidetector row computed tomography (MDCT) is a widely accepted imaging modality for the preoperative staging of gastric cancer that can simultaneously assess locoregional staging, including the gastric mass, regional lymph nodes, and distant metastasis. The diagnostic performance of MDCT for T- and N-staging has been improved by the technical development of isotropic imaging and 3D reformation. Although magnetic resonance imaging (MRI) was not previously used to evaluate gastric cancer due to the modality’s limitations, the development of high-speed sequences has made MRI a feasible tool for the staging of gastric cancer. PMID:24782607

  3. MDCT Imaging Findings of Liver Cirrhosis: Spectrum of Hepatic and Extrahepatic Abdominal Complications

    PubMed Central

    Sangster, Guillermo P.; Previgliano, Carlos H.; Nader, Mathieu; Chwoschtschinsky, Elisa; Heldmann, Maureen G.

    2013-01-01

    Hepatic cirrhosis is the clinical and pathologic result of a multifactorial chronic liver injury. It is well known that cirrhosis is the origin of multiple extrahepatic abdominal complications and a markedly increased risk of hepatocellular carcinoma (HCC). This tumor is the sixth most common malignancy worldwide and the third most common cause of cancer related death. With the rising incidence of HCC worldwide, awareness of the evolution of cirrhotic nodules into malignancy is critical for an early detection and treatment. Adequate imaging protocol selection with dynamic multiphase Multidetector Computed Tomography (MDCT) and reformatted images is crucial to differentiate and categorize the hepatic nodular dysplasia. Knowledge of the typical and less common extrahepatic abdominal manifestations is essential for accurately assessing patients with known or suspected hepatic disease. The objective of this paper is to illustrate the imaging spectrum of intra- and extrahepatic abdominal manifestations of hepatic cirrhosis seen on MDCT. PMID:23986608

  4. Congenital thoracic vascular anomalies: evaluation with state-of-the-art MR imaging and MDCT.

    PubMed

    Hellinger, Jeffrey C; Daubert, Melissa; Lee, Edward Y; Epelman, Monica

    2011-09-01

    Congenital thoracic vascular anomalies include embryologic developmental disorders of the thoracic aorta, aortic arch branch arteries, pulmonary arteries, thoracic systemic veins, and pulmonary veins. Diagnostic evaluation of these anomalies in pediatric patients has evolved with innovations in diagnostic imaging technology. State-of-the-art magnetic resonance (MR) imaging, MR angiography multidetector-row computed tomographic (MDCT) angiography, and advanced postprocessing visualization techniques offer accurate and reliable high-resolution two-dimensional and three-dimensional noninvasive anatomic displays for interpretation and clinical management of congenital thoracic vascular anomalies. This article reviews vascular MR imaging, MR angiography, MDCT angiography, and advanced visualization techniques and applications for the assessment of congenital thoracic vascular anomalies, emphasizing clinical embryology and the characteristic imaging findings.

  5. Robust method for extracting the pulmonary vascular trees from 3D MDCT images

    NASA Astrophysics Data System (ADS)

    Taeprasartsit, Pinyo; Higgins, William E.

    2011-03-01

    Segmentation of pulmonary blood vessels from three-dimensional (3D) multi-detector CT (MDCT) images is important for pulmonary applications. This work presents a method for extracting the vascular trees of the pulmonary arteries and veins, applicable to both contrast-enhanced and unenhanced 3D MDCT image data. The method finds 2D elliptical cross-sections and evaluates agreement of these cross-sections in consecutive slices to find likely cross-sections. It next employs morphological multiscale analysis to separate vessels from adjoining airway walls. The method then tracks the center of the likely cross-sections to connect them to the pulmonary vessels in the mediastinum and forms connected vascular trees spanning both lungs. A ground-truth study indicates that the method was able to detect on the order of 98% of the vessel branches having diameter >= 3.0 mm. The extracted vascular trees can be utilized for the guidance of safe bronchoscopic biopsy.

  6. High-resolution bone imaging for osteoporosis diagnostics and therapy monitoring using clinical MDCT and MRI.

    PubMed

    Baum, T; Karampinos, D C; Liebl, H; Rummeny, E J; Waldt, S; Bauer, J S

    2013-01-01

    Osteoporosis is classified as a public health problem due to its increased risk for fragility fractures. Osteoporotic fractures, in particular spine and hip fractures, are associated with a high morbidity and mortality, and generate immense financial cost. The World Health Organisation (WHO) based the diagnosis of osteoporosis on the measurement of bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA). However, BMD values of subjects with versus without osteoporotic fractures overlap. Furthermore, it was reported that the anti-fracture effects of drugs could be only partially explained by their effects on BMD. Bone strength reflects the integration of BMD and bone quality. The later can be partly determined by measurements of bone microstructure. Therefore, substantial research efforts have been undertaken to assess bone microstructure by using high-resolution imaging techniques, including high-resolution peripheral quantitative computed tomography (hr-pQCT), high-resolution multi-detector computed tomography (MDCT), and high-resolution magnetic resonance imaging (MRI). Clinical MDCT and MRI systems are broadly available and allow an adequate depiction of the bone microstructure at the clinically most important fracture sites, i.e. radius, spine and hip. Bone microstructure parameters and finite element models can be computed in high-resolution MDCT and MR images. These measurements improved the prediction of bone strength beyond the DXA-derived BMD and revealed pharmacotherapy effects, which are partly not captured by BMD. Therefore, high-resolution bone imaging using clinical MDCT and MRI may be beneficial for osteoporosis diagnostics and allow a highly sensitive monitoring of drug treatment, which plays an important role in the prevention of fragility fractures.

  7. Accuracy of multi-detector computed tomography (MDCT) in staging of renal cell carcinoma (RCC): analysis of risk factors for mis-staging and its impact on surgical intervention.

    PubMed

    El-Hefnawy, Ahmed S; Mosbah, Ahmed; El-Diasty, Tarek; Hassan, Mohammed; Shaaban, Atallah A

    2013-08-01

    To assess the accuracy of multi-detector computed tomography (MDCT) in preoperative staging of renal cell carcinoma (RCC) and to detect the possible risk factors for mis-staging. In addition, the impact of radiological mis-staging on surgical decision and operative procedures was evaluated. Data files of 693 patients, who underwent either radical or partial nephrectomy after preoperative staging by MDCT between January 2003 and December 2010, were retrospectively reviewed. Radiological data were compared to surgical and histopathological findings. Patients were classified according to 2009 TNM staging classification. Diagnostic accuracy per stage and its impact on surgical intervention were evaluated. The overall accuracy was 64.5%, and over-stage was detected in 29.5% and under-stage in 6%. Sensitivity and specificity were highest in stage T3b (85 and 99.5%, respectively), while T4 showed the lowest sensitivity and PPV (57 and 45%). Degree of agreement with pathological staging was substantial in T1 (κ = 0.7), fair in T2 (κ = 0. 4), perfect in T3b (κ = 0.81), and slight for the other stages (κ = <0.1). On multivariate analysis, conventional RCC and tumor size > 7 cm represent the significant risk factors (RR: 1.6, 95% CI: 1.1-2.3, P < 0.004 and RR: 2.4, 95% CI: 1.7-3.5, P < 0.001, respectively). Mis-staging was seen to have no negative impact on surgical decision. MDCT is an accepted tool for renal tumor staging. Tumor mis-staging after MDCT is of little clinical importance. Large tumor size >7 cm and conventional RCC are risk factors for tumor mis-staging.

  8. Beak-Like Extension of the Pancreatic Uncinate Process on MDCT: Is It Hyperplasia or Movement?

    PubMed

    Omeri, Ahmad Khalid; Matsumoto, Shunro; Kiyonaga, Maki; Takaji, Ryo; Yamada, Yasunari; Mori, Hiromu

    2016-01-01

    We aimed to evaluate the pancreatic uncinate process with a beak-like extension (BLE) beyond the left border of the superior mesenteric artery, to define the cause of BLE, and to differentiate BLE from hyperplasia. We retrospectively reviewed 1042 triple-phase contrast-enhanced multidetector-row computed tomography (3P-CE-MDCT) examinations of 500 patients. Finally, 38 patients (28 men, 10 women; mean age, 66 years) with 140 3P-CE-MDCT images showing BLE were studied regarding BLE size, contour, and cause. The superior mesenteric artery position was also evaluated. Beak-like extensions were found in 7.6% of patients. Most were caused by movement of the small bowel mesentery (n = 21, 55%), with deviation of mesenteric vessels or mass effect from expanded adjacent organs (n = 3, 8%). Seven patients (18.5%) had true hyperplasia. Beak-like extension is caused by movement of the small bowel mesentery with deviation of mesenteric vessels or by adjacent organ expansion. Beak-like extension closely mimics other pathology on nonenhanced MDCT.

  9. Spectrum of imaging findings on MDCT enterography in patients with small bowel tuberculosis.

    PubMed

    Kalra, N; Agrawal, P; Mittal, V; Kochhar, R; Gupta, V; Nada, R; Singh, R; Khandelwal, N

    2014-03-01

    Abdominal tuberculosis (TB) is the sixth most common extrapulmonary site of involvement. The sites of involvement in abdominal tuberculosis, in descending order of frequency, are lymph nodes, genitourinary tract, peritoneal cavity, and gastrointestinal tract. The radiological armamentarium for evaluating tuberculosis of the small bowel (SBTB) includes barium studies (small bowel follow-through, SBFT), CT (multidetector CT, CT enterography, and CT enteroclysis), ultrasound (sonoenteroclysis), and magnetic resonance imaging (MRI; enterography and enteroclysis). In this review, we illustrate the abnormalities at MDCT enterography in 20 consecutive patients with SB TB and also describe extraluminal findings in these patients. MDCT enterography allows non-invasive good-quality assessment of well-distended bowel loops and the adjacent soft tissues. It displays the thickness and enhancement of the entire bowel wall in all three planes and allows examination of all bowel loops, especially the ileal loops, which are mostly superimposed. The terminal ileum and ileocaecal junction are the most common sites of small bowel involvement in intestinal TB. The most common abnormality is short-segment strictures with symmetrical concentric mural thickening and homogeneous mural enhancement. Other findings include lymphadenopathy, ascites, enteroliths, peritoneal thickening, and enhancement. In conclusion, MDCT enterography is a comprehensive technique for the evaluation of SB TB.

  10. How reliable are 40 MHz IVUS and 64-slice MDCT in characterizing coronary plaque composition? An ex vivo study with histopathological comparison.

    PubMed

    Chopard, Romain; Boussel, Loic; Motreff, Pascal; Rioufol, Gilles; Tabib, Alain; Douek, Philippe; Meyronet, David; Revel, Didier; Finet, Gérard

    2010-04-01

    The present study investigated whether IVUS could serve as a reliable reference in validating MDCT characterization of coronary plaque against a histological gold standard. Twenty-one specimens were postmortem human coronary arteries. Coronary cross-sections were imaged by 40 MHz IVUS and by 64-slice MDCT and characterized histologically as presenting calcified, fibrous or lipid-rich plaques. Plaque composition was analyzed visually and intra-plaque MDCT attenuation was measured in Hounsfield Units (HU). 83 atherosclerotic plaques were identified. IVUS failed to characterize calcified plaque accurately, with a positive predictive value (ppv) of 75% versus 100% for MDCT. Lipid-rich plaque was even less accurately characterized, with ppv of 60 and 68% for IVUS and MDCT respectively. Mean MDCT attenuation was 966 +/- 473 HU for calcified plaque, 83 +/- 35 HU for fibrous plaque and 70.92 HU +/- 41 HU for lipid-rich plaque. No significant difference in mean MDCT attenuation was found between fibrous and lipid-rich plaques (P = 0.276). In vivo validation of MDCT against an IVUS reference thus appears to be an unsuitable and unreliable approach: 40 MHz IVUS suffers from acoustic ambiguities in plaque characterization, and 64-slice MDCT fails to analyze plaque morphology and components accurately.

  11. Anomalous Origin of One Pulmonary Artery Branch From the Aorta: Role of MDCT Angiography.

    PubMed

    Liu, Hui; Juan, Yu-Hsiang; Chen, Jimei; Xie, Zhaofeng; Wang, Qiushi; Zhang, Xiaoshen; Liang, Changhong; Huang, Hongfei; Kwong, Raymond Y; Saboo, Sachin S

    2015-05-01

    The purpose of this study was to evaluate the prevalence, MDCT angiography (MDCTA) appearance, associated congenital cardiovascular abnormalities, and prognosis of anomalous origin of one pulmonary artery from the aorta (AOPA) on the basis of MDCTA. We conducted a retrospective search of patients with AOPA from our database in a single center, consisting of 5729 patients referred for MDCTA with known or suspected congenital heart diseases from transthoracic echocardiography. The clinical information, subtypes of AOPA, associated cardiovascular anomalies, and surgical and clinical outcomes were retrospectively collected and analyzed. The MDCTA images were retrospectively processed for analysis, and the MDCTA and echocardiography images were interpreted by radiologist and cardiologist without knowledge of the actual diagnosis or surgical outcome. AOPA was seen in 19 patients (14 males and five females; median age, 3 months; range, 4 days-21 years) showing a prevalence of 0.33%. Anomalous origin of the right pulmonary artery (AORPA, 89%), proximal origin subtype of the AOPA (89%), and ipsilateral aortic wall origin of AOPA (58%) were more commonly seen. In addition to the benefit of preoperative planning, MDCTA also supplemented echocardiography by providing accurate diagnosis of AOPA and other associated cardiovascular anomalies compared with transthoracic echocardiography (TTE). We found a total of four patients (21%) with misdiagnosis by TTE, including three patients with underdiagnosis of AOPA and one patient with misdiagnosis as transposition of the great arteries. In addition, two other patients had AOPA diagnosed, but the associated patent ductus arteriosus (PDA) was not detected. MDCTA revealed 95% association with other congenital cardiovascular anomalies, including PDA (71% of AORPA), and aortic arch anomalies (100% of anomalous origin of the left pulmonary artery, AOLPA). The types of surgery depended on the MDCTA findings, including the sub-type, origin

  12. Biases and systematics in the observational derivation of galaxy properties: comparing different techniques on synthetic observations of simulated galaxies

    NASA Astrophysics Data System (ADS)

    Guidi, Giovanni; Scannapieco, Cecilia; Walcher, C. Jakob

    2015-12-01

    We study the sources of biases and systematics in the derivation of galaxy properties from observational studies, focusing on stellar masses, star formation rates, gas and stellar metallicities, stellar ages, magnitudes and colours. We use hydrodynamical cosmological simulations of galaxy formation, for which the real quantities are known, and apply observational techniques to derive the observables. We also analyse biases that are relevant for a proper comparison between simulations and observations. For our study, we post-process the simulation outputs to calculate the galaxies' spectral energy distributions (SEDs) using stellar population synthesis models and also generate the fully consistent far-UV-submillimetre wavelength SEDs with the radiative transfer code SUNRISE. We compared the direct results of simulations with the observationally derived quantities obtained in various ways, and found that systematic differences in all studied galaxy properties appear, which are caused by: (1) purely observational biases, (2) the use of mass-weighted and luminosity-weighted quantities, with preferential sampling of more massive and luminous regions, (3) the different ways of constructing the template of models when a fit to the spectra is performed, and (4) variations due to different calibrations, most notably for gas metallicities and star formation rates. Our results show that large differences can appear depending on the technique used to derive galaxy properties. Understanding these differences is of primary importance both for simulators, to allow a better judgement of similarities and differences with observations, and for observers, to allow a proper interpretation of the data.

  13. Live versus Video Observations: Comparing the Reliability and Validity of Two Methods of Assessing Classroom Quality

    ERIC Educational Resources Information Center

    Curby, Timothy W.; Johnson, Price; Mashburn, Andrew J.; Carlis, Lydia

    2016-01-01

    When conducting classroom observations, researchers are often confronted with the decision of whether to conduct observations live or by using pre-recorded video. The present study focuses on comparing and contrasting observations of live and video administrations of the Classroom Assessment Scoring System-PreK (CLASS-PreK). Associations between…

  14. Live versus Video Observations: Comparing the Reliability and Validity of Two Methods of Assessing Classroom Quality

    ERIC Educational Resources Information Center

    Curby, Timothy W.; Johnson, Price; Mashburn, Andrew J.; Carlis, Lydia

    2016-01-01

    When conducting classroom observations, researchers are often confronted with the decision of whether to conduct observations live or by using pre-recorded video. The present study focuses on comparing and contrasting observations of live and video administrations of the Classroom Assessment Scoring System-PreK (CLASS-PreK). Associations between…

  15. The development, validation and application of a multi-detector CT (MDCT) scanner model for assessing organ doses to the pregnant patient and the fetus using Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Gu, J.; Bednarz, B.; Caracappa, P. F.; Xu, X. G.

    2009-05-01

    The latest multiple-detector technologies have further increased the popularity of x-ray CT as a diagnostic imaging modality. There is a continuing need to assess the potential radiation risk associated with such rapidly evolving multi-detector CT (MDCT) modalities and scanning protocols. This need can be met by the use of CT source models that are integrated with patient computational phantoms for organ dose calculations. Based on this purpose, this work developed and validated an MDCT scanner using the Monte Carlo method, and meanwhile the pregnant patient phantoms were integrated into the MDCT scanner model for assessment of the dose to the fetus as well as doses to the organs or tissues of the pregnant patient phantom. A Monte Carlo code, MCNPX, was used to simulate the x-ray source including the energy spectrum, filter and scan trajectory. Detailed CT scanner components were specified using an iterative trial-and-error procedure for a GE LightSpeed CT scanner. The scanner model was validated by comparing simulated results against measured CTDI values and dose profiles reported in the literature. The source movement along the helical trajectory was simulated using the pitch of 0.9375 and 1.375, respectively. The validated scanner model was then integrated with phantoms of a pregnant patient in three different gestational periods to calculate organ doses. It was found that the dose to the fetus of the 3 month pregnant patient phantom was 0.13 mGy/100 mAs and 0.57 mGy/100 mAs from the chest and kidney scan, respectively. For the chest scan of the 6 month patient phantom and the 9 month patient phantom, the fetal doses were 0.21 mGy/100 mAs and 0.26 mGy/100 mAs, respectively. The paper also discusses how these fetal dose values can be used to evaluate imaging procedures and to assess risk using recommendations of the report from AAPM Task Group 36. This work demonstrates the ability of modeling and validating an MDCT scanner by the Monte Carlo method, as well as

  16. The development, validation and application of a multi-detector CT (MDCT) scanner model for assessing organ doses to the pregnant patient and the fetus using Monte Carlo simulations.

    PubMed

    Gu, J; Bednarz, B; Caracappa, P F; Xu, X G

    2009-05-07

    The latest multiple-detector technologies have further increased the popularity of x-ray CT as a diagnostic imaging modality. There is a continuing need to assess the potential radiation risk associated with such rapidly evolving multi-detector CT (MDCT) modalities and scanning protocols. This need can be met by the use of CT source models that are integrated with patient computational phantoms for organ dose calculations. Based on this purpose, this work developed and validated an MDCT scanner using the Monte Carlo method, and meanwhile the pregnant patient phantoms were integrated into the MDCT scanner model for assessment of the dose to the fetus as well as doses to the organs or tissues of the pregnant patient phantom. A Monte Carlo code, MCNPX, was used to simulate the x-ray source including the energy spectrum, filter and scan trajectory. Detailed CT scanner components were specified using an iterative trial-and-error procedure for a GE LightSpeed CT scanner. The scanner model was validated by comparing simulated results against measured CTDI values and dose profiles reported in the literature. The source movement along the helical trajectory was simulated using the pitch of 0.9375 and 1.375, respectively. The validated scanner model was then integrated with phantoms of a pregnant patient in three different gestational periods to calculate organ doses. It was found that the dose to the fetus of the 3 month pregnant patient phantom was 0.13 mGy/100 mAs and 0.57 mGy/100 mAs from the chest and kidney scan, respectively. For the chest scan of the 6 month patient phantom and the 9 month patient phantom, the fetal doses were 0.21 mGy/100 mAs and 0.26 mGy/100 mAs, respectively. The paper also discusses how these fetal dose values can be used to evaluate imaging procedures and to assess risk using recommendations of the report from AAPM Task Group 36. This work demonstrates the ability of modeling and validating an MDCT scanner by the Monte Carlo method, as well as

  17. Computer-aided liver volumetry: performance of a fully-automated, prototype post-processing solution for whole-organ and lobar segmentation based on MDCT imaging.

    PubMed

    Fananapazir, Ghaneh; Bashir, Mustafa R; Marin, Daniele; Boll, Daniel T

    2015-06-01

    To evaluate the performance of a prototype, fully-automated post-processing solution for whole-liver and lobar segmentation based on MDCT datasets. A polymer liver phantom was used to assess accuracy of post-processing applications comparing phantom volumes determined via Archimedes' principle with MDCT segmented datasets. For the IRB-approved, HIPAA-compliant study, 25 patients were enrolled. Volumetry performance compared the manual approach with the automated prototype, assessing intraobserver variability, and interclass correlation for whole-organ and lobar segmentation using ANOVA comparison. Fidelity of segmentation was evaluated qualitatively. Phantom volume was 1581.0 ± 44.7 mL, manually segmented datasets estimated 1628.0 ± 47.8 mL, representing a mean overestimation of 3.0%, automatically segmented datasets estimated 1601.9 ± 0 mL, representing a mean overestimation of 1.3%. Whole-liver and segmental volumetry demonstrated no significant intraobserver variability for neither manual nor automated measurements. For whole-liver volumetry, automated measurement repetitions resulted in identical values; reproducible whole-organ volumetry was also achieved with manual segmentation, p(ANOVA) 0.98. For lobar volumetry, automated segmentation improved reproducibility over manual approach, without significant measurement differences for either methodology, p(ANOVA) 0.95-0.99. Whole-organ and lobar segmentation results from manual and automated segmentation showed no significant differences, p(ANOVA) 0.96-1.00. Assessment of segmentation fidelity found that segments I-IV/VI showed greater segmentation inaccuracies compared to the remaining right hepatic lobe segments. Automated whole-liver segmentation showed non-inferiority of fully-automated whole-liver segmentation compared to manual approaches with improved reproducibility and post-processing duration; automated dual-seed lobar segmentation showed slight tendencies for underestimating the right hepatic lobe

  18. MDCT of acute subaxial cervical spine trauma: a mechanism-based approach.

    PubMed

    Raniga, Sameer B; Menon, Venugopal; Al Muzahmi, Khamis S; Butt, Sajid

    2014-06-01

    Injuries to the spinal column are common and road traffic accidents are the commonest cause. Subaxial cervical spine (C3-C7) trauma encompasses a wide spectrum of osseous and ligamentous injuries, in addition to being frequently associated with neurological injury. Multidetector computed tomography (MDCT) is routinely performed to evaluate acute cervical spine trauma, very often as first-line imaging. MDCT provides an insight into the injury morphology, which in turn reflects the mechanics of injury. This article will review the fundamental biomechanical forces underlying the common subaxial spine injuries and resultant injury patterns or "fingerprints" on MDCT. This systematic and focused analysis enables a more accurate and rapid interpretation of cervical spine CT examinations. Mechanical considerations are important in most clinical and surgical decisions to adequately realign the spine, to prevent neurological deterioration and to facilitate appropriate stabilisation. This review will emphasise the variables on CT that affect the surgical management, as well as imaging "pearls" in differentiating "look-alike" lesions with different surgical implications. It will also enable the radiologist in writing clinically relevant CT reports of cervical spine trauma. Teaching Points • Vertebral bodies and disc bear the axial compression forces, while the ligaments bear the distraction forces.• Compressive forces result in fracture and distractive forces result in ligamentous disruption.• Bilateral facet dislocation is the most severe injury of the flexion-distraction spectrum.• Biomechanics-based CT reading will help to rapidly and accurately identify the entire spectrum of injury.• This approach also helps to differentiate look-alike injuries with different clinical implications.

  19. Coronary fly-through or virtual angioscopy using dual-source MDCT data.

    PubMed

    van Ooijen, Peter M A; de Jonge, Gonda; Oudkerk, Matthijs

    2007-11-01

    Coronary fly-through or virtual angioscopy (VA) has been studied ever since its invention in 2000. However, application was limited because it requires an optimal computed tomography (CT) scan and time-consuming post-processing. Recent advances in post-processing software facilitate easy construction of VA, but until now image quality was insufficient in most patients. The introduction of dual-source multidetector CT (MDCT) could enable VA in all patients. Twenty patients were scanned using a dual-source MDCT (Definition, Siemens, Forchheim, Germany) using a standard coronary artery protocol. Post-processing was performed on an Aquarius Workstation (TeraRecon, San Mateo, Calif.). Length travelled per major branch was recorded in millimetres, together with the time required in minutes. VA could be performed in every patient for each of the major coronary arteries. The mean (range) length of the automated fly-through was 80 (32-107) mm for the left anterior descending (LAD), 75 (21-116) mm for the left circumflex artery (LCx), and 109 (21-190) mm for the right coronary artery (RCA). Calcifications and stenoses were visualised, as well as most side branches. The mean time required was 3 min for LAD, 2.5 min for LCx, and 2 min for the RCA. Dual-source MDCT allows for high quality visualisation of the coronary arteries in every patient because scanning with this machine is independent of the heart rate. This is clearly shown by the successful VA in all patients. Potential clinical value of VA should be determined in the near future.

  20. Ileocaecal Intussusception with a Lead Point: Unusual MDCT Findings of Active Crohn's Disease Involving the Appendix

    PubMed Central

    Ozan, Ebru; Atac, Gokce Kaan; Akincioglu, Egemen; Keskin, Mete; Gulpinar, Kamil

    2015-01-01

    Adult intussusception is a rare entity accounting for 1% of all bowel obstructions. Unlike intussusceptions in children, which are idiopathic in 90% of cases, adult intussusceptions have an identifiable cause (lead point) in the majority of cases. Crohn's disease (CD) may affect any part of the gastrointestinal tract, including the appendix. It was shown to be a predisposing factor for intussusception. Here, we report a rare case of adult intussusception with a lead point, emphasizing diagnostic input of multidetector computed tomography (MDCT) in a patient with active CD that involves the appendix. PMID:26558130

  1. Rare diagnosis of nodular lymphangitis caused by Mycobacterium marinum: MDCT imaging findings

    PubMed Central

    Pedrosa, Margarita; Soriano, Alex; Zboromyrska, Yuliya; Tudo, Griselda; Garcia, Sebastian; Pomes, Jaime

    2014-01-01

    Mycobacterium marinum is an atypical mycobacterium that usually causes a solitary nodule on the hand (“fish tank granuloma”) or less commonly, secondary erythematous channels and nodules spread along lymphatic drainage of the extremity, mimicking sporothricoid skin lesions of nodular lymphangitis. This report presents a case of this rare entity, a nodular lymphangitis caused by Mycobacterium marinum. Multidetector computed tomography (MDCT) imaging was very useful in determining the morphology (cellulitis with a few small subcutaneous nodules and channels) and the extension of the lesion. PMID:24778804

  2. Optimal scan timing for artery-vein separation at whole-brain CT angiography using a 320-row MDCT volume scanner.

    PubMed

    Shirasaka, Takashi; Hiwatashi, Akio; Yamashita, Koji; Kondo, Masatoshi; Hamasaki, Hiroshi; Shimomiya, Yamato; Nakamura, Yasuhiko; Funama, Yoshinori; Honda, Hiroshi

    2017-02-01

    A 320-row multidetector CT (MDCT) is expected for a good artery-vein separation in terms of temporal resolution. However, a shortened scan duration may lead to insufficient vascular enhancement. We assessed the optimal scan timing for the artery-vein separation at whole-brain CT angiography (CTA) when bolus tracking was used at 320-row MDCT. We analyzed 60 patients, who underwent whole-brain four-dimensional CTA. Difference in CT attenuation between the internal carotid artery (ICA) and the superior sagittal sinus (Datt) was calculated in each phase. Using a visual evaluation score for the depiction of arteries and veins, we calculated the difference between the mean score for the intracranial arteries and the mean score for the veins (Dscore). We assessed the time at which the maximum Datt and Dscore were simultaneously observed. The maximum Datt was observed at 6.0 s and 8.0 s in the arterial-dominant phase and at 16.0 s and 18.0 s in the venous-dominant phase after the contrast media arrival time at the ICA (Taa). The maximum Dscore was observed at 6.0 s and 8.0 s in the arterial-dominant phase and at 16.0 s in the venous-dominant phase after the Taa. There were no statistically significant differences in Datt (p = 0.375) or Dscore (p = 0.139) between these scan timings. The optimal scan timing for artery-vein separation at whole-brain CTA was 6.0 s or 8.0 s for the arteries and 16.0 s for the veins after the Taa. Advances in knowledge: Optimal scan timing allowed us to visualize intracranial arteries or veins with minimal superimposition.

  3. Esophagobronchial fistulae: Diagnosis by MDCT with oral contrast swallow examination of a benign and a malignant cause

    PubMed Central

    Hegde, Rahul G; Kalekar, Tushar M; Gajbhiye, Meenakshi I; Bandgar, Amol S; Pawar, Shephali S; Khadse, Gopal J

    2013-01-01

    We report two cases of esophagobronchial fistulae diagnosed by Multi-detector computed tomography (MDCT) oral contrast swallow examination. It is helpful to supplement the CT study with an oral contrast swallow as it aids in confirmation of a suspected fistula and also demonstrates the fistula tract better. We present the clinical details and the imaging findings on MDCT of two cases of esophagobronchial fistulae – one secondary to chronic chest tuberculosis and the other secondary to a squamous cell carcinoma of the upper esophagus – followed by discussion of the etiology, pathogenesis, and imaging of these fistulae. PMID:24082484

  4. Whole-Chest 64-MDCT of Emergency Department Patients with Nonspecific Chest Pain: Radiation Dose and Coronary Artery Image Quality with Prospective ECG Triggering Versus Retrospective ECG Gating

    PubMed Central

    Shuman, William P.; Branch, Kelley R.; May, Janet M.; Mitsumori, Lee M.; Strote, Jared N.; Warren, Bill H.; Dubinsky, Theodore J.; Lockhart, David W.; Caldwell, James H.

    2012-01-01

    Objective The purpose of this study was to compare the patient radiation dose and coronary artery image quality of long-z-axis whole-chest 64-MDCT performed with retrospective ECG gating with those of CT performed with prospective ECG triggering in the evaluation of emergency department patients with nonspecific chest pain. Subjects and Methods Consecutively registered emergency department patients with nonspecific low-to-moderate-risk chest pain underwent whole-chest CT with retrospective gating (n = 41) or prospective triggering (n = 31). Effective patient radiation doses were estimated and compared by use of unpaired Student's t tests. Two reviewers independently scored the quality of images of the coronary arteries, and the scores were compared by use of ordinal logistic regression. Results Age, heart rate, body mass index, and z-axis coverage were not statistically different between the two groups. For retrospective gating, the mean effective radiation dose was 31.8 ± 5.1 mSv; for prospective triggering, the mean effective radiation dose was 9.2 ± 2.2 mSv (prospective triggering 71% lower, p < 0.001). Two of 512 segments imaged with retrospective gating were nonevaluable (0.4%), and two of 394 segments imaged with prospective triggering were nonevaluable (0.5%). Prospectively triggered images were 2.2 (95% CI, 1.1–4.5) times as likely as retrospectively gated images to receive a high image quality score for each segment after adjustment for segment differences (p < 0.05). Conclusion For long-z-axis whole-chest 64-MDCT of emergency department patients with nonspecific chest pain, use of prospective ECG triggering may result in substantially lower patient radiation doses and better coronary artery image quality than is achieved with retrospective ECG gating. PMID:19457832

  5. Whole-chest 64-MDCT of emergency department patients with nonspecific chest pain: Radiation dose and coronary artery image quality with prospective ECG triggering versus retrospective ECG gating.

    PubMed

    Shuman, William P; Branch, Kelley R; May, Janet M; Mitsumori, Lee M; Strote, Jared N; Warren, Bill H; Dubinsky, Theodore J; Lockhart, David W; Caldwell, James H

    2009-06-01

    The purpose of this study was to compare the patient radiation dose and coronary artery image quality of long-z-axis whole-chest 64-MDCT performed with retrospective ECG gating with those of CT performed with prospective ECG triggering in the evaluation of emergency department patients with nonspecific chest pain. Consecutively registered emergency department patients with nonspecific low-to-moderate-risk chest pain underwent whole-chest CT with retrospective gating (n = 41) or prospective triggering (n = 31). Effective patient radiation doses were estimated and compared by use of unpaired Student's t tests. Two reviewers independently scored the quality of images of the coronary arteries, and the scores were compared by use of ordinal logistic regression. Age, heart rate, body mass index, and z-axis coverage were not statistically different between the two groups. For retrospective gating, the mean effective radiation dose was 31.8 +/- 5.1 mSv; for prospective triggering, the mean effective radiation dose was 9.2 +/- 2.2 mSv (prospective triggering 71% lower, p < 0.001). Two of 512 segments imaged with retrospective gating were nonevaluable (0.4%), and two of 394 segments imaged with prospective triggering were nonevaluable (0.5%). Prospectively triggered images were 2.2 (95% CI, 1.1-4.5) times as likely as retrospectively gated images to receive a high image quality score for each segment after adjustment for segment differences (p < 0.05). For long-z-axis whole-chest 64-MDCT of emergency department patients with nonspecific chest pain, use of prospective ECG triggering may result in substantially lower patient radiation doses and better coronary artery image quality than is achieved with retrospective ECG gating.

  6. Globular-cluster stars - Results of theoretical evolution and pulsation studies compared with the observations.

    NASA Technical Reports Server (NTRS)

    Iben, I., Jr.

    1971-01-01

    Survey of recently published studies on globular clusters, and comparison of stellar evolution and pulsation theory with reported observations. The theory of stellar evolution is shown to be capable of describing, in principle, the behavior of a star through all quasi-static stages. Yet, as might be expected, estimates of bulk properties obtained by comparing observations with results of pulsation and stellar atmosphere theory differ somewhat from estimates of these same properties obtained by comparing observations with results of evolution theory. A description is given of how such estimates are obtained, and suggestions are offered as to where the weak points in each theory may lie.

  7. Solar irradiance computations compared with observations at the Baseline Surface Radiation Network Payerne site

    SciTech Connect

    Nowak, Daniela; Vuilleumier, Laurent; Long, Charles N.; Ohmura, Atsumu

    2008-07-18

    Radiative transfer model calculations of solar fluxes during cloud free periods often show considerable discrepancies with surface radiation observations. Many efforts have been undertaken to explain the differences between modeled and observed shortwave downward radiation (SDR). In this study, MODTRAN4v3r1TM (designed later simply as MODTRANTM) was used for model simulations and compared with high quality radiation observations of the Baseline Surface Radiation Network (BSRN) site at Payerne, Switzerland. Results are presented for cloud free shortwave downward radiation calculations. The median differences of modeled minus observed global SDR are small (< 1%) and within the instrumental error. The differences of modeled and observed direct and diffuse SDR show larger discrepancies of -1.8% and 5.2% respectively. The diffuse SDR is generally overestimated by the model and more important, the model to observation linear regression slope and zero-intercept differs significantly from their ideal values of 1 and 0. Possible reasons for the discrepancies are presented and discussed and some modifications are investigated for decreasing such differences between modeled and observed diffuse SDR. However, we could not resolve all the discrepancies. The best agreement is obtained when comparing model simulations whose 550nm aerosol optical depth input is inferred from observations using nine spectral channels, and using BSRN observations performed with a new and more precise shading disk and sun tracker system. In this case, the median bias between model simulations and observed diffuse SDR is -0.4 Wm-2 (< 1%).

  8. Estimated Patient Dose Indexes in Adult and Pediatric MDCT: Comparison of Automatic Tube Voltage Selection With Fixed Tube Current, Fixed Tube Voltage, and Weight-Based Protocols.

    PubMed

    Baker, Mark E; Karim, Wadih; Bullen, Jennifer A; Primak, Andrew N; Dong, Frank F; Herts, Brian R

    2015-09-01

    The purposes of this study were to determine the differences in estimated volumetric CT dose index (CTDIvol) obtained from the topogram before abdominal and pelvic MDCT in adult and pediatric patients using a scan type-based algorithm for selecting kilovoltage (CARE kV) and a fixed and a weight-based Quality Reference mAs for selecting tube (gmAs) current-exposure time product, in comparison with standard protocols, and to determine the bias and variability of estimated CTDIvol vis-à-vis actual CTDIvol using the standard protocols. During a 14-month period, 312 adult and pediatric patients referred for abdominal and pelvic MDCT were included in the study. For all patients, the estimated CTDIvol based on the topogram was recorded: protocol A, CARE kV on and 210 gmAs; protocol B, CARE kV on and 1 gmAs times patient weight (in pounds); and protocol C (standard protocol), CARE kV off, 120 kVp, and 1 gmAs times patient weight (in pounds). For the pediatric patients, estimated CTDIvol for the standard protocol D was calculated with 120 kVp and 150 gmAs. All patients were scanned with the standard protocols, and the actual CTDIvol was recorded. Linear regression models compared the CTDIvol of the three protocols in adults and the fourth for children. The estimated and actual CTDIvol were compared using a t test. Protocol B yielded the lowest estimated CTDIvol (mean, 13.2 mGy for adults and 3.5 mGy for pediatric patients). The estimated CTDIvol overestimated the actual CTDIvol by, on average, 1.07 mGy for adults and 0.3 mGy for children. CARE kV appears to reduce estimated CTDIvol vis-à-vis standard protocols only when a weight-based gmAs is used. Prescan estimated CTDIvol calculations appear to generally overestimate actual CTDIvol.

  9. MDCT Findings of Denim-Sandblasting-Induced Silicosis: a cross-sectional study

    PubMed Central

    2010-01-01

    Background Denim sandblasting is as a novel cause of silicosis in Turkey, with reports of a recent increase in cases and fatal outcomes. We aimed to describe the radiological features of patients exposed to silica during denim sandblasting and define factors related to the development of silicosis. Methods Sixty consecutive men with a history of exposure to silica during denim sandblasting were recruited. All CT examinations were performed using a 64-row multi-detector CT (MDCT). The nodules were qualitatively and semi-quantitatively analyzed by grading nodular profusion (NP) on CT images. Results Silicosis was diagnosed radiologically in 73.3% of patients (44 of 60). The latency period (the time between initial exposure and radiological imaging) and duration of silica exposure was longer in patients diagnosed with silicosis than in those without silicosis (p < 0.05). Nodules were present in all cases with centrilobular type as the commonest (63.6%). All cases of silicosis were clinically classified as accelerated and 11.4% had progressive massive fibrosis (PMF). Mild NP lesions were the most prevalent in all six zones of the lung. The NP score was significantly correlated with the duration of silica exposure, the latency period, presence of PMF, and pleural thickening. Enlarged lymphadenopathy was present in 45.5% of patients. Conclusions The duration of exposure and the latency period are important for development of silicosis in denim sandblasters. MDCT is a useful tool in detecting findings of silicosis in workers who has silica exposure. PMID:20398415

  10. MDCT findings of denim-sandblasting-induced silicosis: a cross-sectional study.

    PubMed

    Ozmen, Cihan Akgul; Nazaroglu, Hasan; Yildiz, Tekin; Bayrak, Aylin Hasanefendioglu; Senturk, Senem; Ates, Gungor; Akyildiz, Levent

    2010-04-17

    Denim sandblasting is as a novel cause of silicosis in Turkey, with reports of a recent increase in cases and fatal outcomes. We aimed to describe the radiological features of patients exposed to silica during denim sandblasting and define factors related to the development of silicosis. Sixty consecutive men with a history of exposure to silica during denim sandblasting were recruited. All CT examinations were performed using a 64-row multi-detector CT (MDCT). The nodules were qualitatively and semi-quantitatively analyzed by grading nodular profusion (NP) on CT images. Silicosis was diagnosed radiologically in 73.3% of patients (44 of 60). The latency period (the time between initial exposure and radiological imaging) and duration of silica exposure was longer in patients diagnosed with silicosis than in those without silicosis (p < 0.05). Nodules were present in all cases with centrilobular type as the commonest (63.6%). All cases of silicosis were clinically classified as accelerated and 11.4% had progressive massive fibrosis (PMF). Mild NP lesions were the most prevalent in all six zones of the lung. The NP score was significantly correlated with the duration of silica exposure, the latency period, presence of PMF, and pleural thickening. Enlarged lymphadenopathy was present in 45.5% of patients. The duration of exposure and the latency period are important for development of silicosis in denim sandblasters. MDCT is a useful tool in detecting findings of silicosis in workers who has silica exposure.

  11. Radiofrequency Ablation of Liver Metastases-Software-Assisted Evaluation of the Ablation Zone in MDCT: Tumor-Free Follow-Up Versus Local Recurrent Disease

    SciTech Connect

    Keil, Sebastian Bruners, Philipp; Schiffl, Katharina; Sedlmair, Martin; Muehlenbruch, Georg; Guenther, Rolf W.; Das, Marco; Mahnken, Andreas H.

    2010-04-15

    The purpose of this study was to investigate differences in change of size and CT value between local recurrences and tumor-free areas after CT-guided radiofrequency ablation (RFA) of hepatic metastases during follow-up by means of dedicated software for automatic evaluation of hepatic lesions. Thirty-two patients with 54 liver metastases from breast or colorectal cancer underwent triphasic contrast-enhanced multidetector-row computed tomography (MDCT) to evaluate hepatic metastatic spread and localization before CT-guided RFA and for follow-up after intervention. Sixteen of these patients (65.1 {+-} 10.3 years) with 30 metastases stayed tumor-free (group 1), while the other group (n = 16 with 24 metastases; 62.0 {+-} 13.8 years) suffered from local recurrent disease (group 2). Applying an automated software tool (SyngoCT Oncology; Siemens Healthcare, Forchheim, Germany), size parameters (volume, RECIST, WHO) and attenuation were measured within the lesions before, 1 day after, and 28 days after RFA treatment. The natural logarithm (ln) of the quotient of the volume 1 day versus 28 days after RFA treament was computed: lnQ1//28/0{sub volume}. Analogously, ln ratios of RECIST, WHO, and attenuation were computed and statistically evaluated by repeated-measures ANOVA. One lesion in group 2 was excluded from further evaluation due to automated missegmentation. Statistically significant differences between the two groups were observed with respect to initial volume, RECIST, and WHO (p < 0.05). Furthermore, ln ratios corresponding to volume, RECIST, and WHO differed significantly between the two groups. Attenuation evaluations showed no significant differences, but there was a trend toward attenuation assessment for the parameter lnQ28/0{sub attenuation} (p = 0.0527), showing higher values for group 1 (-0.4 {+-} 0.3) compared to group 2 (-0.2 {+-} 0.2). In conclusion, hepatic metastases and their zone of coagulation necrosis after RFA differed significantly between tumor

  12. Radiofrequency ablation of liver metastases-software-assisted evaluation of the ablation zone in MDCT: tumor-free follow-up versus local recurrent disease.

    PubMed

    Keil, Sebastian; Bruners, Philipp; Schiffl, Katharina; Sedlmair, Martin; Mühlenbruch, Georg; Günther, Rolf W; Das, Marco; Mahnken, Andreas H

    2010-04-01

    The purpose of this study was to investigate differences in change of size and CT value between local recurrences and tumor-free areas after CT-guided radiofrequency ablation (RFA) of hepatic metastases during follow-up by means of dedicated software for automatic evaluation of hepatic lesions. Thirty-two patients with 54 liver metastases from breast or colorectal cancer underwent triphasic contrast-enhanced multidetector-row computed tomography (MDCT) to evaluate hepatic metastatic spread and localization before CT-guided RFA and for follow-up after intervention. Sixteen of these patients (65.1 + or - 10.3 years) with 30 metastases stayed tumor-free (group 1), while the other group (n = 16 with 24 metastases; 62.0 + or - 13.8 years) suffered from local recurrent disease (group 2). Applying an automated software tool (SyngoCT Oncology; Siemens Healthcare, Forchheim, Germany), size parameters (volume, RECIST, WHO) and attenuation were measured within the lesions before, 1 day after, and 28 days after RFA treatment. The natural logarithm (ln) of the quotient of the volume 1 day versus 28 days after RFA treament was computed: lnQ1//28/0(volume). Analogously, ln ratios of RECIST, WHO, and attenuation were computed and statistically evaluated by repeated-measures ANOVA. One lesion in group 2 was excluded from further evaluation due to automated missegmentation. Statistically significant differences between the two groups were observed with respect to initial volume, RECIST, and WHO (p < 0.05). Furthermore, ln ratios corresponding to volume, RECIST, and WHO differed significantly between the two groups. Attenuation evaluations showed no significant differences, but there was a trend toward attenuation assessment for the parameter lnQ28/0(attenuation) (p = 0.0527), showing higher values for group 1 (-0.4 + or - 0.3) compared to group 2 (-0.2 + or - 0.2). In conclusion, hepatic metastases and their zone of coagulation necrosis after RFA differed significantly between tumor

  13. Comparison of 3D free-breathing coronary MR angiography and 64-MDCT angiography for detection of coronary stenosis in patients with high calcium scores.

    PubMed

    Liu, Xin; Zhao, Xihai; Huang, Jie; Francois, Christopher J; Tuite, David; Bi, Xiaoming; Li, Debiao; Carr, James C

    2007-12-01

    The objective of our study was to compare the diagnostic performance of coronary MR angiography (MRA) and 64-MDCT angiography (MDCTA) for the detection of significant stenosis (> or = 50%) in patients with high calcium scores. Eighteen patients (12 men, six women; mean age, 56 y; age range, 38-77 y) who had at least one calcified plaque with a calcium score of > 100 underwent coronary MRA and conventional coronary angiography (CAG) within 2 weeks of MDCTA. Coronary MRA image quality of the calcified segments was assessed by two observers in consensus on a 4-point scale (1 = not visible, 2 = poor, 3 = good, 4 = excellent) using a 10-segment model from the modified American Heart Association classification. Three experienced radiologists, unaware of the results of conventional CAG, independently assessed for the presence of significant stenosis on MDCTA images and the corresponding MRA images. Receiver operating characteristic (ROC) curves were calculated for each reader using conventional CAG as the gold standard. Thirty-three calcified plaques with a calcium score of > 100 were detected on MDCTA in the 18 patients. The coronary segments with nodal calcification (n = 17) showed a higher mean image quality score than the segments with diffuse calcification (n = 16) (3.47 +/- 0.62 vs 2.94 +/- 0.77, respectively; p < 0.05). Of the 33 coronary segments with calcification, 12 significant stenoses were identified on conventional CAG. The sensitivity, specificity, and area under the ROC curve (AUC) for MRA and MDCTA, respectively, were as follows: reader 1, 75%, 81%, 0.82 versus 75%, 48%, 0.68; reader 2, 83%, 71%, 0.82 versus 67%, 52%, 0.63; and reader 3, 83%, 71%, 0.85 versus 83%, 43%, 0.65, respectively. The average AUC of MRA for the three readers was significantly higher than that of MDCTA (p = 0.030). Coronary MRA has higher image quality for coronary segments with nodal calcification than for coronary segments with diffuse calcification. Coronary MRA has better

  14. Comparison of 3D Free-Breathing Coronary MR Angiography and 64-MDCT Angiography for Detection of Coronary Stenosis in Patients with High Calcium Scores

    PubMed Central

    Liu, Xin; Zhao, Xihai; Huang, Jie; Francois, Christopher J.; Tuite, David; Bi, Xiaoming; Li, Debiao; Carr, James C.

    2014-01-01

    OBJECTIVE The objective of our study was to compare the diagnostic performance of coronary MR angiography (MRA) and 64-MDCT angiography (MDCTA) for the detection of significant stenosis (≥ 50%) in patients with high calcium scores. MATERIALS AND METHODS Eighteen patients (12 men, six women; mean age, 56 y; age range, 38–77 y) who had at least one calcified plaque with a calcium score of > 100 underwent coronary MRA and conventional coronary angiography (CAG) within 2 weeks of MDCTA. Coronary MRA image quality of the calcified segments was assessed by two observers in consensus on a 4-point scale (1 = not visible, 2 = poor, 3 = good, 4 = excellent) using a 10-segment model from the modified American Heart Association classification. Three experienced radiologists, unaware of the results of conventional CAG, independently assessed for the presence of significant stenosis on MDCTA images and the corresponding MRA images. Receiver operating characteristic (ROC) curves were calculated for each reader using conventional CAG as the gold standard. RESULTS Thirty-three calcified plaques with a calcium score of > 100 were detected on MDCTA in the 18 patients. The coronary segments with nodal calcification (n = 17) showed a higher mean image quality score than the segments with diffuse calcification (n = 16) (3.47 ± 0.62 vs 2.94 ± 0.77, respectively; p < 0.05). Of the 33 coronary segments with calcification, 12 significant stenoses were identified on conventional CAG. The sensitivity, specificity, and area under the ROC curve (AUC) for MRA and MDCTA, respectively, were as follows: reader 1, 75%, 81%, 0.82 versus 75%, 48%, 0.68; reader 2, 83%, 71%, 0.82 versus 67%, 52%, 0.63; and reader 3, 83%, 71%, 0.85 versus 83%, 43%, 0.65, respectively. The average AUC of MRA for the three readers was significantly higher than that of MDCTA (p = 0.030). CONCLUSION Coronary MRA has higher image quality for coronary segments with nodal calcification than for coronary segments with

  15. Compatibility between observed and executed finger movements: comparing symbolic, spatial, and imitative cues.

    PubMed

    Brass, M; Bekkering, H; Wohlschläger, A; Prinz, W

    2000-11-01

    Intuitively, one can assume that imitating a movement is an easier task than responding to a symbolic stimulus like a verbal instruction. Support for this suggestion can be found in neuropsychological research as well as in research on stimulus-response compatibility. However controlled experimental evidence for this assumption is still lacking. We used a stimulus-response compatibility paradigm to test the assumption. In a series of experiments, it was tested whether observed finger movements have a stronger influence on finger movement execution than a symbolic or spatial cue. In the first experiment, we compared symbolic cues with observed finger movements using an interference paradigm. Observing finger movements strongly influenced movement execution, irrespective of whether the finger movement was the relevant or the irrelevant stimulus dimension. In the second experiment, effects of observed finger movements and spatial finger cues were compared. The observed finger movement dominated the spatial finger cue. A reduction in the similarity of observed and executed action in the third experiment led to a decrease of the influence of observed finger movement, which demonstrates the crucial role of the imitative relation of observed and executed action for the described effects. The results are discussed in relation to recent models of stimulus-response compatibility. Neurocognitive support for the strong relationship between movement observation and movement execution is reported. Copyright 2000 Academic Press.

  16. [Variations of pulmonary venous drainage and venous ostium index detection in atrial fibrillation patients prior to radiofrequency catheter ablation by MDCT pulmonary venography].

    PubMed

    Shan, Fei; Zhang, Zhi-Yong; Chen, Gang; Miao, Xi-Yin; Liu, Hao; Zhang, Li-Jun; Zeng, Liang-Bin

    2007-04-01

    To evaluate variations of pulmonary venous drainage and venous ostium index (VOI) in patients with atrial fibrillation (AF) prior to radio-frequency catheter ablation (RFCA) by MDCT pulmonary venography. 16-detector row CT pulmonary venography was performed in 64 AF patients referred to RFCA from June, 2005 to May, 2006. Variations in pulmonary venous drainage were observed in volume render imagines. Anterior-posterior and superior-inferior diameters of pulmonary venous ostium were measured on maximum intensity projection images. VOI derived from left superior, left inferior, right superior, right inferior pulmonary veins and variations in pulmonary venous drainage were calculated. Classic pulmonary veins anatomy was found in 11 patients (17.18%), early branching veins in 45 patients (70.31%), left common ostium in 5 patients (7.81%), right common ostia in 1 patient, right accessory (middle) pulmonary vein in 5 patients (7.81%) and left accessory (middle) pulmonary vein in 1 patient (1.56%). VOI of homolateral pulmonary veins and bilateral superior pulmonary veins were similar (P > 0.05) while there was a significant difference on VOIs derived from left superior and right inferior; two inferior, left inferior versus right superior veins (P < 0.05). Right inferior pulmonary venous ostium was most rounded and had the highest index (0.88) and left inferior pulmonary venous ostium was most oval and had the lowest index (0.72). Multidetector row CT pulmonary venography (MDCT-PV) could provide valuable informations on pulmonary venous anatomy in AF patients referred to RFCA and should be used as a routine examination prior to the operation.

  17. Are observation selection methods important when comparing early warning score performance?

    PubMed

    Jarvis, Stuart W; Kovacs, Caroline; Briggs, Jim; Meredith, Paul; Schmidt, Paul E; Featherstone, Peter I; Prytherch, David R; Smith, Gary B

    2015-05-01

    Sicker patients generally have more vital sign assessments, particularly immediately before an adverse outcome, and especially if the vital sign monitoring schedule is driven by an early warning score (EWS) value. This lack of independence could influence the measured discriminatory performance of an EWS. We used a population of 1564,143 consecutive vital signs observation sets collected as a routine part of patients' care. We compared 35 published EWSs for their discrimination of the risk of death within 24h of an observation set using (1) all observations in our dataset, (2) one observation per patient care episode, chosen at random and (3) one observation per patient care episode, chosen as the closest to a randomly selected point in time in each episode. We compared the area under the ROC curve (AUROC) as a measure of discrimination for each of the 35 EWSs under each observation selection method and looked for changes in their rank order. There were no significant changes in rank order of the EWSs based on AUROC between the different observation selection methods, except for one EWS that included age among its components. Whichever method of observation selection was used, the National Early Warning Score (NEWS) showed the highest discrimination of risk of death within 24h. AUROCs were higher when only one observation set was used per episode of care (significantly higher for many EWSs, including NEWS). Vital sign measurements can be treated as if they are independent - multiple observations can be used from each episode of care--when comparing the performance and ranking of EWSs, provided no EWS includes age. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  18. [Current practice of pediatric MDCT in Japan: survey results of demographics and age-based dose reduction].

    PubMed

    Miyazaki, Osamu; Kitamura, Masayuki; Masaki, Hidekazu; Nosaka, Shunsuke; Miyasaka, Mikiko; Kashima, Kyoko; Okada, Yoshiyuki; Tsutsumi, Yoshiyuki

    2005-07-01

    To assess the current practice of pediatric MDCT in Japan, with particular reference to age-related dose adjustment. During the first three months of 2004, a questionnaire was mailed to 996 institutions, among which listed MDCT users ranged from private hospitals to large university-based hospitals. We received responses from 348 (34.9%) institutions. Fifty-three percent of the respondents had four-detector MDCT units. Approximately 70% of examinations were head and 22% were body. Scanning parameters were determined by full-time radiologists in 40%, and by CT technologists in 28% of respondents. Eighty-nine percent (head CT) and 85% (abdominal CT) of respondents indicated that they changed parameters for children. More than 90% changed tube current for optimization. Change was based on the technologist's experience (56%, head CT; 43%, abdominal CT), and automatic exposure control has been used as a basis of mAs control in 17% of respondents for head CT and in 34% for abdominal CT. Age-related mAs settings for abdominal CT were almost the same as those published in a United States survey. Although Japan has approximately 40% of the world's CT units, optimized pediatric MDCT settings might be moved away from a fixed mA protocol as recommended by the FDA and in conformity with the ALARA (as low as reasonably achievable) concept.

  19. Comparing GOSAT Observations of Localized CO2 Enhancements by Large Emitters with Inventory-Based Estimates

    NASA Technical Reports Server (NTRS)

    Janardanan, Rajesh; Maksyutov, Shamil; Oda, Tomohiro; Saito, Makoto; Kaiser, Johannes W.; Ganshin, Alexander; Stohl, Andreas; Matsunaga, Tsuneo; Yoshida, Yukio; Yokota, Tatsuya

    2016-01-01

    We employed an atmospheric transport model to attribute column-averaged CO2 mixing ratios (XCO2) observed by Greenhouse gases Observing SATellite (GOSAT) to emissions due to large sources such as megacities and power plants. XCO2 enhancements estimated from observations were compared to model simulations implemented at the spatial resolution of the satellite observation footprint (0.1deg × 0.1deg). We found that the simulated XCO2 enhancements agree with the observed over several continental regions across the globe, for example, for North America with an observation to simulation ratio of 1.05 +/- 0.38 (p<0.1), but with a larger ratio over East Asia (1.22 +/- 0.32; p<0.05). The obtained observation-model discrepancy (22%) for East Asia is comparable to the uncertainties in Chinese emission inventories (approx.15%) suggested by recent reports. Our results suggest that by increasing the number of observations around emission sources, satellite instruments like GOSAT can provide a tool for detecting biases in reported emission inventories.

  20. Comparing GOSAT Observations of Localized CO2 Enhancements by Large Emitters with Inventory-Based Estimates

    NASA Technical Reports Server (NTRS)

    Janardanan, Rajesh; Maksyutov, Shamil; Oda, Tomohiro; Saito, Makoto; Kaiser, Johannes W.; Ganshin, Alexander; Stohl, Andreas; Matsunaga, Tsuneo; Yoshida, Yukio; Yokota, Tatsuya

    2016-01-01

    We employed an atmospheric transport model to attribute column-averaged CO2 mixing ratios (XCO2) observed by Greenhouse gases Observing SATellite (GOSAT) to emissions due to large sources such as megacities and power plants. XCO2 enhancements estimated from observations were compared to model simulations implemented at the spatial resolution of the satellite observation footprint (0.1deg × 0.1deg). We found that the simulated XCO2 enhancements agree with the observed over several continental regions across the globe, for example, for North America with an observation to simulation ratio of 1.05 +/- 0.38 (p<0.1), but with a larger ratio over East Asia (1.22 +/- 0.32; p<0.05). The obtained observation-model discrepancy (22%) for East Asia is comparable to the uncertainties in Chinese emission inventories (approx.15%) suggested by recent reports. Our results suggest that by increasing the number of observations around emission sources, satellite instruments like GOSAT can provide a tool for detecting biases in reported emission inventories.

  1. Increasing bone sclerosis during bortezomib therapy in multiple myeloma patients: results of a reduced-dose whole-body MDCT study.

    PubMed

    Schulze, Maximilian; Weisel, Katja; Grandjean, Caroline; Oehrlein, Katharina; Zago, Manola; Spira, Daniel; Horger, Marius

    2014-01-01

    The objective of our study was to assess the frequency, location, extent, and patterns of bone sclerosis occurring in patients with multiple myeloma (MM) during bortezomib-based therapy. From June 2003 through December 2011, 593 whole-body reduced-dose MDCT studies were performed of 79 consecutive patients receiving bortezomib. The median surveillance time was 21 months (range, 3-67 months). Baseline studies were compared with follow-up studies during therapy (follow-up 1), at the end of therapy (follow-up 2), and 12 months after cessation of bortezomib therapy (follow-up 3). We recorded any sclerotic change occurring inside or along the margins of the osteolytic lesions, in the cancellous bone, or inside preexistent medullary or extramedullary lesions. The time point of occurrence of bone sclerosis was correlated with the best hematologic response category. Fourteen (17.7%) patients developed focal (n = 11) or diffuse (n = 3) bone sclerosis. The time window from bortezomib initiation to radiographic detection of bone sclerosis was 8 months (SD, 7 months). Sclerosis occurred at multiple sites (n = 7) or at an isolated site (n = 7). On subsequent whole-body reduced-dose MDCT studies, sclerosis further increased in seven (50%) patients. Hematologic best response during bortezomib treatment was complete response (n = 1), very good partial response (n = 2), partial response (n = 8), and stable disease (n = 3). Radiologic response at the time of sclerosis detection was partial response (n = 8), stable disease (n = 2), and progressive disease (n = 4). Bone remineralization may occur during bortezomib-based therapy for MM in a substantial proportion of patients. The extent, location, and patterns of sclerosis differ among patients and are unpredictable. Sclerosis was documented even in patients showing suboptimal hematologic response.

  2. Comparison of hepatic MDCT, MRI, and DSA to explant pathology for the detection and treatment planning of hepatocellular carcinoma

    PubMed Central

    Ladd, Lauren M.; Tirkes, Temel; Tann, Mark; Agarwal, David M.; Johnson, Matthew S.; Tahir, Bilal; Sandrasegaran, Kumaresan

    2016-01-01

    Background/Aims The diagnosis and treatment plan for hepatocellular carcinoma (HCC) can be made from radiologic imaging. However, lesion detection may vary depending on the imaging modality. This study aims to evaluate the sensitivities of hepatic multidetector computed tomography (MDCT), magnetic resonance imaging (MRI), and digital subtraction angiography (DSA) in the detection of HCC and the consequent management impact on potential liver transplant patients. Methods One hundred and sixteen HCC lesions were analyzed in 41 patients who received an orthotopic liver transplant (OLT). All of the patients underwent pretransplantation hepatic DSA, MDCT, and/or MRI. The imaging results were independently reviewed retrospectively in a blinded fashion by two interventional and two abdominal radiologists. The liver explant pathology was used as the gold standard for assessing each imaging modality. Results The sensitivity for overall HCC detection was higher for cross-sectional imaging using MRI (51.5%, 95% confidence interval [CI]=36.2-58.4%) and MDCT (49.8%, 95% CI=43.7-55.9%) than for DSA (41.7%, 95% CI=36.2-47.3%) (P=0.05). The difference in false-positive rate was not statistically significant between MRI (22%), MDCT (29%), and DSA (29%) (P=0.67). The sensitivity was significantly higher for detecting right lobe lesions than left lobe lesions for all modalities (MRI: 56.1% vs. 43.1%, MDCT: 55.0% vs. 42.0%, and DSA: 46.9% vs. 33.9%; all P<0.01). The sensitivities of the three imaging modalities were also higher for lesions ≥2 cm vs. <2 cm (MRI: 73.4% vs. 32.7%, MDCT: 66.9% vs. 33.8%, and DSA: 62.2% vs. 24.1%; all P<0.01). The interobserver correlation was rated as very good to excellent. Conclusion The sensitivity for detecting HCC is higher for MRI and MDCT than for DSA, and so cross-sectional imaging modalities should be used to evaluate OLT candidacy. PMID:27987537

  3. C-arm cone beam CT perfusion imaging in the angiographic suite: a comparison with MDCT perfusion imaging

    PubMed Central

    Niu, Kai; Yang, Pengfei; Wu, Yijing; Struffert, Tobias; Doerfler, Arnd; Schafer, Sebastian; Royalty, Kevin; Strother, Charles; Chen, Guang-Hong

    2015-01-01

    Purpose and background Perfusion imaging in the angiography suite may provide a way to reduce time from stroke onset to endovascular revascularization of patients with a large vessel occlusion. Our purpose was to compare CBCTP with MDCTP. Materials and Methods Data from seven subjects with both MDCTP and CBCTP were retrospectively processed and analyzed. Two algorithms were used to enhance temporal resolution, temporal sampling density and reduce noise of CBCT data before generating perfusion maps. Two readers performed qualitative image quality evaluation on maps using a 5-point scale. ROIs indicating CBF/CBV abnormalities were drawn. Quantitative analyses were performed using the Sørensen–Dice coefficients to quantify the similarity of abnormalities. A non-inferiority hypothesis was tested to compare CBCTP against CBCTP. Results Averaged image quality score for MDCTP and CBCTP images was 2.4 and 2.3 respectively. Averaged confidence scores in diagnosis were both 1.4 for MDCT and CBCT; averaged confidence scores on presence of a CBV/CBF mismatch was 1.7 (κ = 0.50) and 1.5 (κ = 0.64). For MDCTP and CBCTP maps the average score of confidence in making treatment decision was 1.4 (κ = 0.79) and 1.3 (κ = 0.90). Area under visual grading characteristic (AVGC) for the above four qualitative quality score showed an average AVGC of 0.50 with 95% confidence level cover centered at the mean for both readers. Sørensen–Dice coefficient for CBF maps is 0.81 and for CBV maps is 0.55. Conclusions After post-processing methods were applied to enhance image quality for CBCTP maps, the CBCTP maps were not inferior to those generated from MDCTP. PMID:26892987

  4. Healthcare outcomes assessed with observational study designs compared with those assessed in randomized trials.

    PubMed

    Anglemyer, Andrew; Horvath, Hacsi T; Bero, Lisa

    2014-04-29

    Researchers and organizations often use evidence from randomized controlled trials (RCTs) to determine the efficacy of a treatment or intervention under ideal conditions. Studies of observational designs are often used to measure the effectiveness of an intervention in 'real world' scenarios. Numerous study designs and modifications of existing designs, including both randomized and observational, are used for comparative effectiveness research in an attempt to give an unbiased estimate of whether one treatment is more effective or safer than another for a particular population.A systematic analysis of study design features, risk of bias, parameter interpretation, and effect size for all types of randomized and non-experimental observational studies is needed to identify specific differences in design types and potential biases. This review summarizes the results of methodological reviews that compare the outcomes of observational studies with randomized trials addressing the same question, as well as methodological reviews that compare the outcomes of different types of observational studies. To assess the impact of study design (including RCTs versus observational study designs) on the effect measures estimated.To explore methodological variables that might explain any differences identified.To identify gaps in the existing research comparing study designs. We searched seven electronic databases, from January 1990 to December 2013.Along with MeSH terms and relevant keywords, we used the sensitivity-specificity balanced version of a validated strategy to identify reviews in PubMed, augmented with one term ("review" in article titles) so that it better targeted narrative reviews. No language restrictions were applied. We examined systematic reviews that were designed as methodological reviews to compare quantitative effect size estimates measuring efficacy or effectiveness of interventions tested in trials with those tested in observational studies

  5. Accuracy of contrast-enhanced ultrasound (CEUS) in the identification and characterization of traumatic solid organ lesions in children: a retrospective comparison with baseline US and CE-MDCT.

    PubMed

    Menichini, Guendalina; Sessa, Barbara; Trinci, Margherita; Galluzzo, Michele; Miele, Vittorio

    2015-11-01

    Localized low-energy abdominal trauma is very frequent in the pediatric population. The findings of several studies have shown that ultrasonography (US) can represent a useful and cost-effective tool in the evaluation of blunt abdominal trauma both in adults and children. However, many parenchymal injuries are not correctly visualized at baseline US examination. The introduction of specific US contrast agents contrast-enhanced ultrasound (CEUS) has enabled a better identification of traumatic organ injuries. The correct use of CEUS could therefore identify and select the children who need further diagnostic investigation computed tomography (CT), avoiding unnecessary radiation and iodinated contrast medium exposure. The purpose of our study was to assess the sensibility and feasibility of CEUS in the assessment of low-energy abdominal trauma compared to baseline US in pediatric patients, using contrast-enhanced MDCT as the reference standard. We retrospectively reviewed 73 children (51 M and 22 F; mean age 8.7 ± 2.8 years) who presented in our Emergency Department between October 2012 and October 2013, with history of minor abdominal trauma according to the Abbreviated Injury Scale and who underwent US, CEUS, and CE-MDCT. Inclusion criteria were: male or female, aged 0-16, hemodynamically stable patients with a history of minor blunt abdominal trauma. Exclusion criteria were adulthood, hemodynamical instability, history of major trauma. Sensitivity, specificity, PPV, NPV, and accuracy were determined for US and CEUS compared to MDCT. 6/73 patients were negative at US, CEUS, and MDCT for the presence of organ injuries. In the remaining 67 patients, US depicted 26/67 parenchymal lesions. CEUS identified 67/67 patients (67/67) with parenchymal lesions: 21 lesions of the liver (28.8 %), 26 lesions of the spleen (35.6 %), 7 lesions of right kidney (9.6 %), 13 lesions of left kidney. MDCT confirmed all parenchymal lesions (67/67). Thus, the diagnostic performance of

  6. Impact of Aortic Valve Calcification, as Measured by MDCT, on Survival in Patients With Aortic Stenosis

    PubMed Central

    Clavel, Marie-Annick; Pibarot, Philippe; Messika-Zeitoun, David; Capoulade, Romain; Malouf, Joseph; Aggarval, Shivani; Araoz, Phillip A.; Michelena, Hector I.; Cueff, Caroline; Larose, Eric; Miller, Jordan D.; Vahanian, Alec; Enriquez-Sarano, Maurice

    2014-01-01

    BACKGROUND Aortic valve calcification (AVC) load measures lesion severity in aortic stenosis (AS) and is useful for diagnostic purposes. Whether AVC predicts survival after diagnosis, independent of clinical and Doppler echocardiographic AS characteristics, has not been studied. OBJECTIVES This study evaluated the impact of AVC load, absolute and relative to aortic annulus size (AVCdensity), on overall mortality in patients with AS under conservative treatment and without regard to treatment. METHODS In 3 academic centers, we enrolled 794 patients (mean age, 73 ± 12 years; 274 women) diagnosed with AS by Doppler echocardiography who underwent multidetector computed tomography (MDCT) within the same episode of care. Absolute AVC load and AVCdensity (ratio of absolute AVC to cross-sectional area of aortic annulus) were measured, and severe AVC was separately defined in men and women. RESULTS During follow-up, there were 440 aortic valve implantations (AVIs) and 194 deaths (115 under medical treatment). Univariate analysis showed strong association of absolute AVC and AVCdensity with survival (both, p < 0.0001) with a spline curve analysis pattern of threshold and plateau of risk. After adjustment for age, sex, coronary artery disease, diabetes, symptoms, AS severity on hemodynamic assessment, and LV ejection fraction, severe absolute AVC (adjusted hazard ratio [HR]: 1.75; 95% confidence interval [CI]: 1.04 to 2.92; p = 0.03) or severe AVCdensity (adjusted HR: 2.44; 95% CI: 1.37 to 4.37; p = 0.002) independently predicted mortality under medical treatment, with additive model predictive value (all, p ≤ 0.04) and a net reclassification index of 12.5% (p = 0.04). Severe absolute AVC (adjusted HR: 1.71; 95% CI: 1.12 to 2.62; p = 0.01) and severe AVCdensity (adjusted HR: 2.22; 95% CI: 1.40 to 3.52; p = 0.001) also independently predicted overall mortality, even with adjustment for time-dependent AVI. CONCLUSIONS This large-scale, multicenter outcomes study of

  7. Chest pain evaluation in the emergency department: can MDCT provide a comprehensive evaluation?

    PubMed

    White, Charles S; Kuo, Dick; Kelemen, Mark; Jain, Vineet; Musk, Amy; Zaidi, Eram; Read, Katrina; Sliker, Clint; Prasad, Rajnish

    2005-08-01

    The purpose of our study was to determine whether MDCT can provide a comprehensive assessment of cardiac and noncardiac causes of chest pain in stable emergency department patients. Patients with chest pain who presented to the emergency department without definitive findings of acute myocardial infarction based on history, physical examination, and ECG were recruited immediately after the initial clinical assessment. For each patient, the emergency department physician was asked whether a CT scan would normally have been ordered on clinical grounds (e.g., to exclude pulmonary embolism). Each consenting patient underwent enhanced ECG-gated 16-MDCT. Ten cardiac phases were reconstructed. The images were evaluated for cardiac (coronary calcium and stenosis, ejection fraction, and wall motion and perfusion) and significant noncardiac (pulmonary embolism, dissection, pneumonia, and so forth) causes of chest pain. Correlation was made between the presence of significant cardiac and noncardiac findings on CT and the final clinical diagnosis based on history, examination, and any subsequent cardiac workup at the 1-month follow-up by a consensus of three physicians. Sixty-nine patients met all criteria for enrollment in the study, of whom 45 (65%) would not otherwise have undergone CT. Fifty-two patients (75%) had no significant CT findings and a final diagnosis of clinically insignificant chest pain. Thirteen patients (19%) had significant CT findings (cardiac, 10; noncardiac, 3) concordant with the final diagnosis. CT failed to suggest a diagnosis in two patients (3%), both of whom proved to have clinically significant coronary artery stenoses. In two patients (3%), CT overdiagnosed a coronary stenosis. Sensitivity and specificity for the establishment of a cardiac cause of chest pain were 83% and 96%, respectively. Overall sensitivity and specificity for all other cardiac and noncardiac causes were 87% and 96%, respectively. ECG-gated MDCT appears to be logistically

  8. Assessing Observer Accuracy in Continuous Recording of Rate and Duration: Three Algorithms Compared

    ERIC Educational Resources Information Center

    Mudford, Oliver C.; Martin, Neil T.; Hui, Jasmine K. Y.; Taylor, Sarah Ann

    2009-01-01

    The three algorithms most frequently selected by behavior-analytic researchers to compute interobserver agreement with continuous recording were used to assess the accuracy of data recorded from video samples on handheld computers by 12 observers. Rate and duration of responding were recorded for three samples each. Data files were compared with…

  9. Helping Teenagers Stop Smoking: Comparative Observations across Youth Settings in Cardiff

    ERIC Educational Resources Information Center

    Bowles, Hannah; Maher, Alison; Sage, Robert

    2009-01-01

    Objective: This paper presents comparative observations between schools/colleges, youth centres, and specialist youth provision, in relation to delivery of the 2tuff2puff six-week smoking cessation and awareness programme to young people in Cardiff. Design: A six-week smoking cessation programme was delivered to 12-23 year olds in various youth…

  10. On the Law of Comparative Judgment: Scaling with Intransitive Observers and Multidimensional Stimuli.

    ERIC Educational Resources Information Center

    Hull, R. Bruce, IV; Buhyoff, Gregory J.

    1981-01-01

    Intransitives in observers' preference judgements for multidimensional natural landscape scenes are examined. Thurstone's Law of Comparative Judgement (LCJ) psychophysical scaling routine is used to scale landscape preference. Both the method of Rank Ordering (RO) and the method of Paired Comparisons (PC) are used to gather the raw data necessary…

  11. Helping Teenagers Stop Smoking: Comparative Observations across Youth Settings in Cardiff

    ERIC Educational Resources Information Center

    Bowles, Hannah; Maher, Alison; Sage, Robert

    2009-01-01

    Objective: This paper presents comparative observations between schools/colleges, youth centres, and specialist youth provision, in relation to delivery of the 2tuff2puff six-week smoking cessation and awareness programme to young people in Cardiff. Design: A six-week smoking cessation programme was delivered to 12-23 year olds in various youth…

  12. On the Law of Comparative Judgment: Scaling with Intransitive Observers and Multidimensional Stimuli.

    ERIC Educational Resources Information Center

    Hull, R. Bruce, IV; Buhyoff, Gregory J.

    1981-01-01

    Intransitives in observers' preference judgements for multidimensional natural landscape scenes are examined. Thurstone's Law of Comparative Judgement (LCJ) psychophysical scaling routine is used to scale landscape preference. Both the method of Rank Ordering (RO) and the method of Paired Comparisons (PC) are used to gather the raw data necessary…

  13. Diagnostics comparing sea surface temperature feedbacks from operational hurricane forecasts to observations

    NASA Astrophysics Data System (ADS)

    Lloyd, Ian D.; Marchok, Timothy; Vecchi, Gabriel A.

    2011-04-01

    This paper examines the ability of recent versions of the Geophysical Fluid Dynamics Laboratory Operational Hurricane Forecast Model (GHM) to reproduce the observed relationship between hurricane intensity and hurricane-induced Sea Surface Temperature (SST) cooling. The analysis was performed by taking a Lagrangian composite of all hurricanes in the North Atlantic from 1998-2009 in observations and 2005-2009 for the GHM. A marked improvement in the intensity-SST relationship for the GHM compared to observations was found between the years 2005 and 2006-2009 due to the introduction of warm-core eddies, a representation of the loop current, and changes to the drag coefficient parameterization for bulk turbulent flux computation. A Conceptual Hurricane Intensity Model illustrates the essential steady-state characteristics of the intensity-SST relationship and is explained by two coupled equations for the atmosphere and ocean. The conceptual model qualitatively matches observations and the 2006-2009 period in the GHM, and presents supporting evidence for the conclusion that weaker upper oceanic thermal stratification in the Gulf of Mexico, caused by the introduction of the loop current and warm core eddies, is crucial to explaining the observed SST-intensity pattern. The diagnostics proposed by the conceptual model offer an independent set of metrics for comparing operational hurricane forecast models to observations.

  14. Comparing the Scoring of Human Decomposition from Digital Images to Scoring Using On-site Observations.

    PubMed

    Dabbs, Gretchen R; Bytheway, Joan A; Connor, Melissa

    2017-01-25

    When in forensic casework or empirical research in-person assessment of human decomposition is not possible, the sensible substitution is color photographic images. To date, no research has confirmed the utility of color photographic images as a proxy for in situ observation of the level of decomposition. Sixteen observers scored photographs of 13 human cadavers in varying decomposition stages (PMI 2-186 days) using the Total Body Score system (total n = 929 observations). The on-site TBS was compared with recorded observations from digital color images using a paired samples t-test. The average difference between on-site and photographic observations was -0.20 (t = -1.679, df = 928, p = 0.094). Individually, only two observers, both students with <1 year of experience, demonstrated TBS statistically significantly different than the on-site value, suggesting that with experience, observations of human decomposition based on digital images can be substituted for assessments based on observation of the corpse in situ, when necessary.

  15. Comparing Temperature and Precipitation Extremes Across Multiple Reanalyses and Gridded in Situ Observational Datasets

    NASA Astrophysics Data System (ADS)

    Donat, M.; Alexander, L. V.; Sillmann, J.; Wild, S.; Zwiers, F. W.; Lippmann, T.

    2014-12-01

    Changes in climate extremes are often monitored using global gridded datasets of climate extremes based on in situ observations or reanalysis data. This study assesses the consistency of temperature and precipitation extremes between these datasets. We compare temporal evolution and spatial patterns of annual climate extremes indices across multiple global gridded datasets of in situ observations and reanalyses to make inferences on the robustness of the obtained results. While there are distinct differences in the actual values of extremes, normalized time series generally compare well and temporal correlations are high for temperature extremes, in particular for the most recent three decades when satellite data are available for assimilation. Extreme precipitation is characterized by higher temporal and spatial variability than extreme temperatures, and there is less agreement between different datasets than for temperature. However, reasonable agreement between gridded precipitation extremes from the different datasets remains. While there is general agreement between the different reanalyses and gridded observational data in regions with dense observational coverage, different reanalyses show trends of partly opposing signs in areas where in situ observations are sparse, e.g. over parts of Africa and tropical South America. However, in the absence of reliable observations it is difficult to assess which reanalyses are more realistic here than others. Using data from the 20th Century reanalysis and a novel century-long gridded dataset of extremes we also investigate consistency of extremes from these two datasets back to the beginning of the 20th Century. Global average time series of different extremes indices compare generally well over the past 70 years but show larger differences before around 1940. However, in areas with good observational coverage, including North America, Europe and Australia, agreement remains strong also throughout the earlier decades

  16. Journal Club: Comparison of assessment of preoperative pulmonary vasculature in patients with non-small cell lung cancer by non-contrast- and 4D contrast-enhanced 3-T MR angiography and contrast-enhanced 64-MDCT.

    PubMed

    Ohno, Yoshiharu; Nishio, Mizuho; Koyama, Hisanobu; Yoshikawa, Takeshi; Matsumoto, Sumiaki; Seki, Shinichiro; Sugimura, Kazuro

    2014-03-01

    The purpose of this article is to prospectively and directly compare the capabilities of non-contrast-enhanced MR angiography (MRA), 4D contrast-enhanced MRA, and contrast-enhanced MDCT for assessing pulmonary vasculature in patients with non-small cell lung cancer (NSCLC) before surgical treatment. A total of 77 consecutive patients (41 men and 36 women; mean age, 71 years) with pathologically proven and clinically assessed stage I NSCLC underwent thin-section contrast-enhanced MDCT, non-contrast-enhanced and contrast-enhanced MRA, and surgical treatment. The capability for anomaly assessment of the three methods was independently evaluated by two reviewers using a 5-point visual scoring system, and final assessment for each patient was made by consensus of the two readers. Interobserver agreement for pulmonary arterial and venous assessment was evaluated with the kappa statistic. Then, sensitivity, specificity, and accuracy for the detection of anomalies were directly compared among the three methods by use of the McNemar test. Interobserver agreement for pulmonary artery and vein assessment was substantial or almost perfect (κ=0.72-0.86). For pulmonary arterial and venous variation assessment, there were no significant differences in sensitivity, specificity, and accuracy among non-contrast-enhanced MRA (pulmonary arteries: sensitivity, 77.1%; specificity, 97.4%; accuracy, 87.7%; pulmonary veins: sensitivity, 50%; specificity, 98.5%; accuracy, 93.2%), 4D contrast-enhanced MRA (pulmonary arteries: sensitivity, 77.1%; specificity, 97.4%; accuracy, 87.7%; pulmonary veins: sensitivity, 62.5%; specificity, 100.0%; accuracy, 95.9%), and thin-section contrast-enhanced MDCT (pulmonary arteries: sensitivity, 91.4%; specificity, 89.5%; accuracy, 90.4%; pulmonary veins: sensitivity, 50%; specificity, 100.0%; accuracy, 95.9%) (p>0.05). Pulmonary vascular assessment of patients with NSCLC before surgical resection by non-contrast-enhanced MRA can be considered equivalent to

  17. A Rare Presentation of an Entrapment in a Liver Transplant Candidate Depicted by MDCT Angiography

    PubMed Central

    Kantarci, Mecit; Aydin, Unal; Doganay, Selim; Aydinli, Bulent; Yuce, Ihsan; Polat, Kamil Yalcin

    2010-01-01

    Hypertrophic caudate lobe veins can mimic a normal venous configuration. In cases of multiple vascular collaterals, Doppler evaluations must be conducted, and the flow direction of these veins as well as the IVC should be evaluated. If the flow in the IVC is reversed, Budd-Chiari syndrome should be suspected; moreover, at the supra diaphragmatic level, which may be considered a blind spot, particularly for radiologists, a web should be searched for in the area where the IVC opens into the right atrium. In this study, we present the unique findings of multidetector computed tomography (MDCT) angiography for a liver transplant candidate with Budd-Chiari syndrome caused by a web in the proximal IVC. PMID:25610132

  18. Regression modeling of longitudinal data with outcome-dependent observation times: extensions and comparative evaluation.

    PubMed

    Tan, Kay See; French, Benjamin; Troxel, Andrea B

    2014-11-30

    Conventional longitudinal data analysis methods assume that outcomes are independent of the data-collection schedule. However, the independence assumption may be violated, for example, when a specific treatment necessitates a different follow-up schedule than the control arm or when adverse events trigger additional physician visits in between prescheduled follow-ups. Dependence between outcomes and observation times may introduce bias when estimating the marginal association of covariates on outcomes using a standard longitudinal regression model. We formulate a framework of outcome-observation dependence mechanisms to describe conditional independence given observed observation-time process covariates or shared latent variables. We compare four recently developed semi-parametric methods that accommodate one of these mechanisms. To allow greater flexibility, we extend these methods to accommodate a combination of mechanisms. In simulation studies, we show how incorrectly specifying the outcome-observation dependence may yield biased estimates of covariate-outcome associations and how our proposed extensions can accommodate a greater number of dependence mechanisms. We illustrate the implications of different modeling strategies in an application to bladder cancer data. In longitudinal studies with potentially outcome-dependent observation times, we recommend that analysts carefully explore the conditional independence mechanism between the outcome and observation-time processes to ensure valid inference regarding covariate-outcome associations.

  19. Multiphase contrast-saline mixture injection with dual-flow in 64-row MDCT coronary CTA.

    PubMed

    Cao, Lizhen; Du, Xiangying; Li, Pengyu; Liu, Yaou; Li, Kuncheng

    2009-03-01

    To explore the feasibility of multiphase contrast-saline mixture with dual-flow injection technique for visualization of right ventricular (RV) cavity and interventricular septum (IVS) in 64-row multidetector computed tomography (MDCT) coronary angiography. Twenty-four patients underwent coronary CT angiography (CTA) imaging with 64-row MDCT. In twelve patients (group A), 60 ml contrast medium (CM) bolus was followed by 40 ml saline, and in the other twelve patients (group B), 50 ml CM bolus was followed by 50 ml contrast-saline mixture at 60:40 ratio. The CM, saline and contrast-saline mixture flow rate were all 5.0 ml/s. Two experienced radiologists measured the CT values of ascending aorta, descending aorta, pulmonary artery and RV, rated the uniformity of RV cavity, the visualization of coronary arteries and IVS independently. By Kappa test, agreement between the two radiologists was 0.93 and 0.86 concerning the CT value measurements and the grades of the three indexes, respectively. By t-test, the mean CT values of ascending aorta and descending aorta of the two groups had no statistical difference (t=1.459, P>0.05; t=1.619, P>0.05); while the mean CT values of pulmonary artery and RV cavity had statistical differences (t=8.316, P<0.05; t=10.372, P<0.05). By two-related rank sum test, according to the visualization of coronary arteries and the uniformity of RV cavity, there were no statistical differences (U=66.00, P>0.05; U=54.00, P>0.05); while according to the visualization of IVS, group B was better than group A (U=8.00, P<0.05). In coronary CTA, a contrast-saline mixture after CM bolus can provide clear visualization of RV and IVS and LV without impairing coronary CTA image.

  20. Diagnostic Value and Interreader Agreement of the Pancreaticolienal Gap in Pancreatic Cancer on MDCT

    PubMed Central

    Schawkat, Khoschy; Kühn, Wolfgang; Inderbitzin, Daniel; Gloor, Beat; Heverhagen, Johannes T.; Runge, Val Murray; Christe, Andreas

    2016-01-01

    Objective The aim of this retrospective study was to evaluate the diagnostic value and measure interreader agreement of the pancreaticolienal gap (PLG) in the assessment of imaging features of pancreatic carcinoma (PC) on contrast-enhanced multi-detector computed tomography (CE-MDCT). Materials and Methods CE-MDCT studies in the portal venous phase were retrospectively reviewed for 66 patients with PC. The age- and gender-matched control group comprised 103 healthy individuals. Three radiologists with different levels of experience independently measured the PLG (the minimum distance of the pancreatic tail to the nearest border of the spleen) in the axial plane. The interreader agreement of the PLG and the receiver operating characteristic (ROC) curve was used to calculate the accuracy of the technique. Results While the control group (n = 103) showed a median PLG of 3 mm (Range: 0 – 39mm) the PC patients had a significantly larger PLG of 15mm (Range: 0 – 53mm)(p < 0.0001). A ROC curve demonstrated a cutoff-value of >12 mm for PC, with a sensitivity of 58.2% (95% CI = 45.5–70.1), specificity of 84.0% (95% CI = 75.6–90.4) and an area under the ROC curve of 0.714 (95% CI = 0.641 to 0.780). The mean interreader agreement showed correlation coefficient r of 0.9159. The extent of the PLG did not correlate with tumor stage but did correlate with pancreatic density (fatty involution) and age, the density decreased by 4.1 HU and the PLG increased by 0.8 mm within every 10 y. Conclusion The significant interreader agreement supports the use of the PLG as a characterizing feature of pancreatic cancer independent of the tumor stage on an axial plane. The increase in the PLG with age may represent physiological atrophy of the pancreatic tail. PMID:27893776

  1. GRACE principles: recognizing high-quality observational studies of comparative effectiveness.

    PubMed

    Dreyer, Nancy A; Schneeweiss, Sebastian; McNeil, Barbara J; Berger, Marc L; Walker, Alec M; Ollendorf, Daniel A; Gliklich, Richard E

    2010-06-01

    Nonrandomized comparative effectiveness studies contribute to clinical and biologic understanding of treatments by themselves, via subsequent confirmation in a more targeted randomized clinical trial, or through advances in basic science. Although methodological challenges and a lack of accepted principles to assess the quality of nonrandomized studies of comparative effectiveness have limited the practical use of these investigations, even imperfect studies can contribute useful information if they are thoughtfully designed, well conducted, carefully analyzed, and reported in a manner that addresses concerns from skeptical readers and reviewers. The GRACE (Good Research for Comparative Effectiveness) principles have been developed to help healthcare providers, researchers, journal readers, and editors evaluate the quality inherent in observational research studies of comparative effectiveness. The GRACE principles were developed by experienced academic and private sector researchers and were vetted over several years through presentation, critique, and consensus building among outcomes researchers, pharmacoepidemiologists, and other medical scientists and via formal review by the International Society of Pharmacoepidemiology. In contrast to other documents that guide systematic review and reporting, the GRACE principles are high-level concepts about good practice for nonrandomized comparative effectiveness research. The GRACE principles comprise a series of questions to guide evaluation. No scoring system is provided or encouraged, as interpretation of these observational studies requires weighing of all available evidence, tempered by judgment regarding the applicability of the studies to routine care.

  2. Comparing the diameters and visual albedos derived from radar and infrared observations

    NASA Astrophysics Data System (ADS)

    Taylor, P.; Howell, E.; Nolan, M.; Springmann, A.; Vervack, R., Jr.; Fernandez, Y.; Magri, C.

    2014-07-01

    Radar observations provide direct measurements of the physical sizes of near-Earth objects, independent of visual albedo, composition, and thermal properties, which can act as calibration or sanity checks for models of thermal-infrared emission by small bodies. Thermal modeling of infrared observations by the NEOWISE [1--3] and ExploreNEOs (Spitzer) [4--6] programs has provided diameters and visual albedos for several hundred near-Earth objects. Meanwhile, since 1998, the Arecibo radar program has detected over 350 near-Earth objects, including more than 40 objects from each of the NEOWISE and ExploreNEOs catalogs, providing rotation-rate, size, and shape constraints depending on the strength and resolution of the received echoes. In addition, our observations with the SpeX instrument on the NASA IRTF provide a sample of roughly two dozen objects, observed on multiple dates at different viewing geometries, that were also observed by the Arecibo radar and NEOWISE and/or ExploreNEOs programs. We will compare the diameters and visual albedos inferred from radar to those derived from thermal modeling of infrared observations from WISE, Spitzer, and/or the IRTF, and look for correlations between the outliers and their sizes, shapes, compositions, and viewing geometries, all of which can affect the assumptions made in the process of standard thermal modeling.

  3. An Automated Comparative Observation System for Sun-Induced Chlorophyll Fluorescence of Vegetation Canopies

    PubMed Central

    Zhou, Xijia; Liu, Zhigang; Xu, Shan; Zhang, Weiwei; Wu, Jun

    2016-01-01

    Detecting sun-induced chlorophyll fluorescence (SIF) offers a new approach for remote sensing photosynthesis. However, to analyse the response characteristics of SIF under different stress states, a long-term time-series comparative observation of vegetation under different stress states must be carried out at the canopy scale, such that the similarities and differences in SIF change law can be summarized under different time scales. A continuous comparative observation system for vegetation canopy SIF is designed in this study. The system, which is based on a high-resolution spectrometer and an optical multiplexer, can achieve comparative observation of multiple targets. To simultaneously measure the commonly used vegetation index and SIF in the O2-A and O2-B atmospheric absorption bands, the following parameters are used: a spectral range of 475.9 to 862.2 nm, a spectral resolution of approximately 0.9 nm, a spectral sampling interval of approximately 0.4 nm, and the signal-to-noise ratio (SNR) can be as high as 1000:1. To obtain data for both the upward radiance of the vegetation canopy and downward irradiance data with a high SNR in relatively short time intervals, the single-step integration time optimization algorithm is proposed. To optimize the extraction accuracy of SIF, the FluorMOD model is used to simulate sets of data according to the spectral resolution, spectral sampling interval and SNR of the spectrometer in this continuous observation system. These data sets are used to determine the best parameters of Fraunhofer Line Depth (FLD), Three FLD (3FLD) and the spectral fitting method (SFM), and 3FLD and SFM are confirmed to be suitable for extracting SIF from the spectral measurements. This system has been used to observe the SIF values in O2-A and O2-B absorption bands and some commonly used vegetation index from sweet potato and bare land, the result of which shows: (1) the daily variation trend of SIF value of sweet potato leaves is basically same

  4. An Automated Comparative Observation System for Sun-Induced Chlorophyll Fluorescence of Vegetation Canopies.

    PubMed

    Zhou, Xijia; Liu, Zhigang; Xu, Shan; Zhang, Weiwei; Wu, Jun

    2016-05-27

    Detecting sun-induced chlorophyll fluorescence (SIF) offers a new approach for remote sensing photosynthesis. However, to analyse the response characteristics of SIF under different stress states, a long-term time-series comparative observation of vegetation under different stress states must be carried out at the canopy scale, such that the similarities and differences in SIF change law can be summarized under different time scales. A continuous comparative observation system for vegetation canopy SIF is designed in this study. The system, which is based on a high-resolution spectrometer and an optical multiplexer, can achieve comparative observation of multiple targets. To simultaneously measure the commonly used vegetation index and SIF in the O₂-A and O₂-B atmospheric absorption bands, the following parameters are used: a spectral range of 475.9 to 862.2 nm, a spectral resolution of approximately 0.9 nm, a spectral sampling interval of approximately 0.4 nm, and the signal-to-noise ratio (SNR) can be as high as 1000:1. To obtain data for both the upward radiance of the vegetation canopy and downward irradiance data with a high SNR in relatively short time intervals, the single-step integration time optimization algorithm is proposed. To optimize the extraction accuracy of SIF, the FluorMOD model is used to simulate sets of data according to the spectral resolution, spectral sampling interval and SNR of the spectrometer in this continuous observation system. These data sets are used to determine the best parameters of Fraunhofer Line Depth (FLD), Three FLD (3FLD) and the spectral fitting method (SFM), and 3FLD and SFM are confirmed to be suitable for extracting SIF from the spectral measurements. This system has been used to observe the SIF values in O₂-A and O₂-B absorption bands and some commonly used vegetation index from sweet potato and bare land, the result of which shows: (1) the daily variation trend of SIF value of sweet potato leaves is

  5. Demystifying the Enigma of Smoking – An Observational Comparative Study on Tobacco Smoking

    PubMed Central

    Nallakunta, Rajesh; Reddy, Sudhakara Reddy; Chennoju, Sai Kiran

    2016-01-01

    Introduction Smoking is a hazardous habit which causes definite changes in the oral cavity, consequently there exist changes in the mucosa when subjected to smoking. Palatal mucosa is first to be affected. The present study determines the palatal status in reverse smokers and conventional smokers. Aim To study and compare the clinical, cytological and histopathological changes in palatal mucosa among reverse and conventional smokers. Materials and Methods Study sample was categorized into two groups. Group 1 comprised of 20 subjects with the habit of reverse smoking and Group 2 comprised of 20 subjects with the habit of conventional smoking. Initially, clinical appearance of the palatal mucosa was recorded, followed by a cytological smear and biopsy of the involved area among all the subjects. The findings were studied clinically, the specimens were analysed cytologically and histopathologically, and compared among the two groups. Results The severity of clinical changes of the palatal mucosa among reverse smokers was statistically significant when compared to those of conventional smokers. There was no statistically significant difference observed in cytological staging between the groups with a p-value of 0.35. The histopathological changes in both the groups showed a significant difference with a p-value of 0.02. A significant positive correlation was observed between the clinical appearance, and cytological, histopathological changes. Conclusion Profound clinically aggressive changes were observed in group I compared to group II. Severity of dysplastic changes have been detected in few subjects through histopathological examination irrespective of no prominent clinical and cytological changes observed among the two groups. PMID:27190962

  6. [Comparative observation on acupuncture-moxibustion and western medication for treatment of sudden deafness].

    PubMed

    Fan, Xin-hua; Ding, Ya-nan; Chang, Xiang-hui; Ouyang, Yu-lu; Xie, Qiang

    2010-08-01

    To compare the therapeutic effect on sudden deafness between acupuncture and moxibustion therapy of excitation-focus transfer and routine medication. Eighty cases of sudden deafness were randomly divided into two groups, 40 cases in each one. Acupuncture and moxibustion therapy of excitation-focus transfer was adopted in observation group on Yongquan (KI 1) (with reducing and slightly heavy manipulation), Tinggong (SI 19), Tinghui (GB 2) and Ermen (TE 21), and associated with suspending moxibustion for thermal sensitization on Yongquan (KI 1). In control group, the routine medications were given. The therapeutic effects of two groups were compared with each other. After three sessions of treatment, dB value of hearing loss in two groups decreased (P<0.05, P<0.01), but the improvement of hearing in observation group was superior to that in control group (P<0.05). The total effective rate was 80.0% (32/40) in observation group, which was better than that 55.0% (22/40) in control group (P<0.05). Acupuncture and moxibustion therapy of excitation-focus transfer presents superior therapeutic effect on sudden deafness as compared with the routine western therapy.

  7. Comparing USGS national seismic hazard maps with internet-based macroseismic intensity observations

    NASA Astrophysics Data System (ADS)

    Mak, Sum; Schorlemmer, Danijel

    2016-04-01

    Verifying a nationwide seismic hazard assessment using data collected after the assessment has been made (i.e., prospective data) is a direct consistency check of the assessment. We directly compared the predicted rate of ground motion exceedance by the four available versions of the USGS national seismic hazard map (NSHMP, 1996, 2002, 2008, 2014) with the actual observed rate during 2000-2013. The data were prospective to the two earlier versions of NSHMP. We used two sets of somewhat independent data, namely 1) the USGS "Did You Feel It?" (DYFI) intensity reports, 2) instrumental ground motion records extracted from ShakeMap stations. Although both are observed data, they come in different degrees of accuracy. Our results indicated that for California, the predicted and observed hazards were very comparable. The two sets of data gave consistent results, implying robustness. The consistency also encourages the use of DYFI data for hazard verification in the Central and Eastern US (CEUS), where instrumental records are lacking. The result showed that the observed ground-motion exceedance was also consistent with the predicted in CEUS. The primary value of this study is to demonstrate the usefulness of DYFI data, originally designed for community communication instead of scientific analysis, for the purpose of hazard verification.

  8. Anatomical knowledge gain through a clay-modeling exercise compared to live and video observations.

    PubMed

    Kooloos, Jan G M; Schepens-Franke, Annelieke N; Bergman, Esther M; Donders, Rogier A R T; Vorstenbosch, Marc A T M

    2014-01-01

    Clay modeling is increasingly used as a teaching method other than dissection. The haptic experience during clay modeling is supposed to correspond to the learning effect of manipulations during exercises in the dissection room involving tissues and organs. We questioned this assumption in two pretest-post-test experiments. In these experiments, the learning effects of clay modeling were compared to either live observations (Experiment I) or video observations (Experiment II) of the clay-modeling exercise. The effects of learning were measured with multiple choice questions, extended matching questions, and recognition of structures on illustrations of cross-sections. Analysis of covariance with pretest scores as the covariate was used to elaborate the results. Experiment I showed a significantly higher post-test score for the observers, whereas Experiment II showed a significantly higher post-test score for the clay modelers. This study shows that (1) students who perform clay-modeling exercises show less gain in anatomical knowledge than students who attentively observe the same exercise being carried out and (2) performing a clay-modeling exercise is better in anatomical knowledge gain compared to the study of a video of the recorded exercise. The most important learning effect seems to be the engagement in the exercise, focusing attention and stimulating time on task.

  9. A comparative study of multiwavelength theoretical and observed light curves of Cepheid variables

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Anupam; Kanbur, Shashi M.; Marconi, Marcella; Rejkuba, Marina; Singh, Harinder P.; Ngeow, Chow-Choong

    2017-04-01

    We analyse the theoretical light curves of Cepheid variables at optical (UBVRI) and near-infrared (JKL) wavelengths using the Fourier decomposition and principal component analysis methods. The Cepheid light curves are based on the full-amplitude, non-linear, convective hydrodynamical models for chemical compositions representative of Cepheids in the Galaxy (Y = 0.28, Z = 0.02), Large Magellanic Cloud (Y = 0.25, Z = 0.008) and Small Magellanic Cloud (Y = 0.25, Z = 0.004). We discuss the variation of light-curve parameters with different compositions and mass-luminosity levels as a function of period and wavelength, and compare our results with observations. For a fixed composition, the theoretical amplitude parameters decrease while the phase parameters increase with wavelength, similar to the observed Fourier parameters. The optical amplitude parameters obtained using canonical mass-luminosity Cepheid models exhibit a large offset with respect to the observations for periods between 7 and 11 d, when compared to the non-canonical mass-luminosity levels. The central minimum of the Hertzsprung progression for amplitude parameters shifts to the longer periods with decrease/increase in metallicity/wavelength for both theoretical and observed light curves. The principal components for Magellanic Cloud Cepheid models are consistent with observations at optical wavelengths. We also observe two distinct populations in the first principal component for optical and near-infrared wavelengths while the J band contributes to both populations. Finally, we take into account the variation in the convective efficiency by increasing the adopted mixing length parameter from the standard 1.5 to 1.8. This results in a zero-point offset in the bolometric mean magnitudes and in amplitude parameters (except close to 10 d), reducing the systematically large difference in theoretical amplitudes.

  10. Multidetector computed tomography for the evaluation of coronary artery disease; the diagnostic accuracy in calcified coronary arteries, comparing with IVUS imaging.

    PubMed

    Park, Jong Kwan; Kim, Jong Youn; Kwon, Hyuck Moon; Kim, Tae Hoon; Oh, Seung-Jin; Hong, Bum-Kee; Yoon, Young Won; Min, Pil-Ki; Kwon, Sung Woo; Lee, Byoung Kwon

    2014-05-01

    Contrast enhanced multidetector computed tomography (MDCT) has been used as an alternative to coronary angiography for the assessment of coronary artery disease in the patient of the intermediate risk group. However, coronary calcium is a known limiting factor for MDCT evaluation. We investigated the diagnostic accuracy of 64-channel MDCT with each coronary artery calcium score (CACS) by compared with intravascular ultrasound (IVUS) imaging. A total of 54 symptomatic patients with intermediate-risk (10 females, mean age 59.9±6.9 years, Framingham point scores 9-20) with 162 sites who had a culprit lesion on 64-channel MDCT before performing coronary angiography with IVUS were enrolled. Patients were divided into 4 subgroups depending on CACS: 0, 1-99, 100-399, and >400. Lesion length, external elastic membrane (EEM) cross sectional area (CSA), minimal luminal area, and plaque area were measured and compared between IVUS and MDCT. The correlation coefficients for the measurements of the EEM CSA, lumen CSA, and plaque area were r=0.514, r=0.837, and r=0.578, respectively. Furthermore, there were close correlation of plaque area between four subgroups of CACS (r=0.671, r=0.623, r=0.562, r=0.571, respectively). Despite the increase in CACS, the geometric analysis of coronary arteries using with 64-channel MDCT was comparable with IVUS in symptomatic patient of the intermediate risk group.

  11. Multidetector Computed Tomography for the Evaluation of Coronary Artery Disease; The Diagnostic Accuracy in Calcified Coronary Arteries, Comparing with IVUS Imaging

    PubMed Central

    Park, Jong Kwan; Kim, Jong Youn; Kwon, Hyuck Moon; Kim, Tae Hoon; Oh, Seung-Jin; Hong, Bum-Kee; Yoon, Young Won; Min, Pil-Ki; Kwon, Sung Woo

    2014-01-01

    Purpose Contrast enhanced multidetector computed tomography (MDCT) has been used as an alternative to coronary angiography for the assessment of coronary artery disease in the patient of the intermediate risk group. However, coronary calcium is a known limiting factor for MDCT evaluation. We investigated the diagnostic accuracy of 64-channel MDCT with each coronary artery calcium score (CACS) by compared with intravascular ultrasound (IVUS) imaging. Materials and Methods A total of 54 symptomatic patients with intermediate-risk (10 females, mean age 59.9±6.9 years, Framingham point scores 9-20) with 162 sites who had a culprit lesion on 64-channel MDCT before performing coronary angiography with IVUS were enrolled. Patients were divided into 4 subgroups depending on CACS: 0, 1-99, 100-399, and >400. Lesion length, external elastic membrane (EEM) cross sectional area (CSA), minimal luminal area, and plaque area were measured and compared between IVUS and MDCT. Results The correlation coefficients for the measurements of the EEM CSA, lumen CSA, and plaque area were r=0.514, r=0.837, and r=0.578, respectively. Furthermore, there were close correlation of plaque area between four subgroups of CACS (r=0.671, r=0.623, r=0.562, r=0.571, respectively). Conclusion Despite the increase in CACS, the geometric analysis of coronary arteries using with 64-channel MDCT was comparable with IVUS in symptomatic patient of the intermediate risk group. PMID:24719125

  12. The energy budget of stellar magnetic fields: comparing non-potential simulations and observations

    NASA Astrophysics Data System (ADS)

    Lehmann, L. T.; Jardine, M. M.; Vidotto, A. A.; Mackay, D. H.; See, V.; Donati, J.-F.; Folsom, C. P.; Jeffers, S. V.; Marsden, S. C.; Morin, J.; Petit, P.

    2017-03-01

    The magnetic geometry of the surface magnetic fields of more than 55 cool stars have now been mapped using spectropolarimetry. In order to better understand these observations, we compare the magnetic field topology at different surface scale sizes of observed and simulated cool stars. For ease of comparison between the high-resolution non-potential magnetofrictional simulations and the relatively low-resolution observations, we filter out the small-scale field in the simulations using a spherical harmonics decomposition. We show that the large-scale field topologies of the solar-based simulations produce values of poloidal/toroidal fields and fractions of energy in axisymmetric modes which are similar to the observations. These global non-potential evolution model simulations capture key magnetic features of the observed solar-like stars through the processes of surface flux transport and magnetic flux emergence. They do not, however, reproduce the magnetic field of M-dwarfs or stars with dominantly toroidal field. Furthermore, we analyse the magnetic field topologies of individual spherical harmonics for the simulations and discover that the dipole is predominately poloidal, while the quadrupole shows the highest fraction of toroidal fields. Magnetic field structures smaller than a quadrupole display a fixed ratio between the poloidal and toroidal magnetic energies.

  13. Comparing Aircraft Observations of Snowfall to Forecasts Using Single or Two Moment Bulk Water Microphysics Schemes

    NASA Astrophysics Data System (ADS)

    Molthan, A.

    2010-12-01

    High resolution weather forecast models with explicit prediction of hydrometeor type, size distribution, and fall speed may be useful in the development of precipitation retrievals, by providing representative characteristics of frozen hydrometeors. Several single or double-moment microphysics schemes are currently available within the Weather Research and Forecasting (WRF) model, allowing for the prediction of up to three ice species. Each scheme incorporates different assumptions regarding the characteristics of their ice classes, particularly in terms of size distribution, density, and fall speed. In addition to the prediction of hydrometeor content, these schemes must accurately represent the vertical profile of water vapor to account for possible attenuation, along with the size distribution, density, and shape characteristics of ice crystals that are relevant to microwave scattering. An evaluation of a particular scheme requires the availability of field campaign measurements. The Canadian CloudSat/CALIPSO Validation Project (C3VP) obtained measurements of ice crystal shapes, size distributions, fall speeds, and precipitation during several intensive observation periods. In this study, C3VP observations obtained during the 22 January 2007 synoptic-scale snowfall event are compared against WRF model output, based upon forecasts using four single-moment and two double-moment schemes available as of version 3.1. Schemes are compared against aircraft observations by examining differences in size distribution, density, and content. In addition to direct measurements from aircraft probes, simulated precipitation can also be converted to equivalent, remotely sensed characteristics through the use of the NASA Goddard Satellite Data Simulator Unit. Outputs from high resolution forecasts are compared against radar and satellite observations emphasizing differences in assumed crystal shape and size distribution characteristics.

  14. Comparing Aircraft Observations of Snowfall to Forecasts Using Single or Two Moment Bulk Water Microphysics Schemes

    NASA Technical Reports Server (NTRS)

    Molthan, Andrew L.

    2010-01-01

    High resolution weather forecast models with explicit prediction of hydrometeor type, size distribution, and fall speed may be useful in the development of precipitation retrievals, by providing representative characteristics of frozen hydrometeors. Several single or double-moment microphysics schemes are currently available within the Weather Research and Forecasting (WRF) model, allowing for the prediction of up to three ice species. Each scheme incorporates different assumptions regarding the characteristics of their ice classes, particularly in terms of size distribution, density, and fall speed. In addition to the prediction of hydrometeor content, these schemes must accurately represent the vertical profile of water vapor to account for possible attenuation, along with the size distribution, density, and shape characteristics of ice crystals that are relevant to microwave scattering. An evaluation of a particular scheme requires the availability of field campaign measurements. The Canadian CloudSat/CALIPSO Validation Project (C3VP) obtained measurements of ice crystal shapes, size distributions, fall speeds, and precipitation during several intensive observation periods. In this study, C3VP observations obtained during the 22 January 2007 synoptic-scale snowfall event are compared against WRF model output, based upon forecasts using four single-moment and two double-moment schemes available as of version 3.1. Schemes are compared against aircraft observations by examining differences in size distribution, density, and content. In addition to direct measurements from aircraft probes, simulated precipitation can also be converted to equivalent, remotely sensed characteristics through the use of the NASA Goddard Satellite Data Simulator Unit. Outputs from high resolution forecasts are compared against radar and satellite observations emphasizing differences in assumed crystal shape and size distribution characteristics.

  15. Identifying tools for comparing simulations and observations of spectral-line data cubes

    NASA Astrophysics Data System (ADS)

    Koch, Eric W.; Ward, Caleb G.; Offner, Stella; Loeppky, Jason L.; Rosolowsky, Erik W.

    2017-10-01

    We present a statistical framework to compare spectral-line data cubes of molecular clouds and use the framework to perform an analysis of various statistical tools developed from methods proposed in the literature. We test whether our methods are sensitive to changes in the underlying physical properties of the clouds or whether their behaviour is governed by random fluctuations. We perform a set of 32 self-gravitating magnetohydrodynamic simulations that test all combinations of five physical parameters - Mach number, plasma parameter, virial parameter, driving scales and solenoidal driving fraction - each of which can be set to a low or high value. We create mock observational data sets of 13CO(1-0) emission from each simulation. We compare these mock data to those generated from a set of baseline simulations using pseudo-distance metrics based on 18 different statistical techniques that have previously been used to study molecular clouds. We analyse these results using methods from the statistical field of experimental design and find that several of the statistics can reliably track changes in the underlying physics. Our analysis shows that the interactions between parameters are often among the most significant effects. A small fraction of statistics are also sensitive to changes in magnetic field properties. We use this framework to compare the set of simulations to observations of three nearby star-forming regions: NGC 1333, Oph A and IC 348. We find that no one simulation agrees significantly better with the observations, although there is evidence that the high Mach number simulations are more consistent with the observations.

  16. Comparing different Ultraviolet Imaging Spectrograph (UVIS) occultation observations using modeling of water vapor jets

    NASA Astrophysics Data System (ADS)

    Portyankina, Ganna; Esposito, Larry W.; Hansen, Candice; Aye, Klaus-Michael

    2016-10-01

    Motivation: On March 11, 2016 the Cassini UVIS observed its 6th star occultation by Enceladus' plume. This observation was aimed to determine variability in the total gas flux from the Enceladus' southern polar region. The analysis of the received data suggests that the total gas flux is moderately increased comparing to the average gas flux observed by UVIS from 2005 to 2011 [1]. However, UVIS detected variability in individual jets. In particular, Baghdad 1 is more collimated in 2016 than in 2005, meaning its gas escapes at higher velocity.Model and fits: We use 3D DSMC model for water vapor jets to compare different UVIS occultation observations from 2005 to 2016. The model traces test articles from jets' sources [2] into space and results in coordinates and velocities for a set of test particles. We convert particle positions into the particle number density and integrate along UVIS line of sight (LoS) for each time step of the UVIS observation using precise observational geometry derived from SPICE [3]. We integrate all jets that are crossed by the LoS and perform constrained least-squares fit of resulting modeled opacities to the observed data to solved for relative strengths of jets. The geometry of each occultation is specific, for example, during solar occultation in 2010 UVIS LoS was almost parallel to tiger stripes, which made it possible to distinguish jets venting from different tiger stripes. In 2011 Eps Orionis occultation LoS was perpendicular to tiger stripes and thus many of the jets were geometrically overlapping. Solar occultation provided us with the largest inventory of active jets - our model fit detects at least 43 non-zero jet contributions. Stellar occultations generally have lower temporal resolution and observe only a sub-set of these jets: 2011 Eps Orionis needs minimum 25 non-zero jets to fit UVIS data. We will discuss different occultations and models fits, including the most recent Epsilon Orionis occultation of 2016.[1] Hansen et al

  17. Mid-Continental Intensive Field Campaign Atmospheric CO2 Observations Compared to Forward Models

    NASA Astrophysics Data System (ADS)

    Diaz, L. I.; Davis, K. J.; Miles, N. L.; Richardson, S.; Schuh, A. E.; Denning, A.; Andrews, A. E.; Jacobson, A. R.; Corbin, K.

    2009-12-01

    Two commonly used approaches to study source/sinks of CO2 are the “bottom-up” and the “top-down” methods. Because of the large discrepancies between these approaches, the North America Carbon Program devised the Mid-Continental Intensive field campaign (MCI). The MCI campaign aims at improving the carbon flux estimates of both approaches with a combination of atmospheric transport models, a denser network of in-situ atmospheric CO2 measurements and agricultural inventories. The first step in evaluating and improving inverse models is to compare observed CO2 concentrations and predicted concentrations from forwards models. This study shows a model-data comparison at multiple temporal and spatial scales for the 2007 growing season. In-situ tower-based observations are compared to two different forwards models: NOAA’s Carbon Tracker and CSU’s SiBcrop-RAMS. Observations from two tall towers of the National Oceanic and Atmospheric Administration (NOAA) and five towers of Ring2 PSU network are used for this comparison. The towers are located in an intensively agricultural region of the North American continent. Comparisons to date show that both models predict higher mid-summer concentrations at three sites located in the “corn belt.” Both models have difficulty reproducing the observed monthly-average spatial gradient across these sites. The models also underestimate the maximum observed spatial gradients in daytime, daily-averaged boundary layer concentrations. These results suggest that the rapid photosynthetic rates found in corn are not yet well-simulated in these models, and that these data, when used in inversions, will provide a valuable constraint on regional fluxes.

  18. Bayesian Techniques for Comparing Time-dependent GRMHD Simulations to Variable Event Horizon Telescope Observations

    NASA Astrophysics Data System (ADS)

    Kim, Junhan; Marrone, Daniel P.; Chan, Chi-Kwan; Medeiros, Lia; Özel, Feryal; Psaltis, Dimitrios

    2016-12-01

    The Event Horizon Telescope (EHT) is a millimeter-wavelength, very-long-baseline interferometry (VLBI) experiment that is capable of observing black holes with horizon-scale resolution. Early observations have revealed variable horizon-scale emission in the Galactic Center black hole, Sagittarius A* (Sgr A*). Comparing such observations to time-dependent general relativistic magnetohydrodynamic (GRMHD) simulations requires statistical tools that explicitly consider the variability in both the data and the models. We develop here a Bayesian method to compare time-resolved simulation images to variable VLBI data, in order to infer model parameters and perform model comparisons. We use mock EHT data based on GRMHD simulations to explore the robustness of this Bayesian method and contrast it to approaches that do not consider the effects of variability. We find that time-independent models lead to offset values of the inferred parameters with artificially reduced uncertainties. Moreover, neglecting the variability in the data and the models often leads to erroneous model selections. We finally apply our method to the early EHT data on Sgr A*.

  19. Simulations of Solar Induced Fluorescence compared to observations from GOSAT and GOME-2 Satellites

    NASA Astrophysics Data System (ADS)

    Baker, I. T.; Berry, J. A.; Frankenberg, C.; Joiner, J.; Van der Tol, C.; Lee, J. E.; Denning, S.

    2014-12-01

    Observations of Solar-Induced Fluorescence (SIF) are currently retrieved from the GOSAT and GOME-2 satellites, and will become available from OCO-2 shortly. The GOSAT (and OCO-2) satellite has a midday overpass time, while GOME-2 has a variable observation of approximately 0800-1100 local time. Previous studies have demonstrated a linear relationship between SIF and Gross Primary Productivity (GPP), but lack the ability to investigate causes of spatiotemporal variability. We demonstrate an ability to simulate SIF using a landsurface model (the Simple Biosphere Model; SIB) for direct comparison to observations. We calculate fluorescence yield based on known relationships between photosynthesis and fluorescence, and calculate total SIF using existing leaf-to-canopy scaling factors. We find that simulated SIF exceeds GOSAT retrieved SIF, especially in tropical and Boreal forests. Simulated SIF exceeds GOME-2 values in Boreal forest and in lower-productivity areas such as marginal desert and tundra. Observed SIF GOME-2 in croplands is significantly higher than simulations. SIF simulated for low- and high-productivity grassland and savanna show much less seasonal and interannual amplitude when compared to values from both satellites, implicating that model phenology and/or response to meteorological forcing is damped. Simulated SIF seasonal cycles are similar to observed from both satellites, and simulations are able to reproduce drought events such as occurred in Russia in 2010 and the Central USA in 2012. As simulated SIF more closely resembles observations, model estimates of GPP become more robust, as does our ability to understand and recreate the mechanisms involved in vegetation response to seasonal cycles and anomalous stress events such as drought.

  20. COMPARING THE LIGHT CURVES OF SIMULATED TYPE Ia SUPERNOVAE WITH OBSERVATIONS USING DATA-DRIVEN MODELS

    SciTech Connect

    Diemer, Benedikt; Kessler, Richard; Graziani, Carlo; Jordan, George C. IV; Lamb, Donald Q.; Long, Min; Van Rossum, Daniel R.

    2013-08-20

    We propose a robust, quantitative method to compare the synthetic light curves of a Type Ia supernova (SN Ia) explosion model with a large set of observed SNe Ia, and derive a figure of merit for the explosion model's agreement with observations. The synthetic light curves are fit with the data-driven model SALT2 which returns values for stretch, color, and magnitude at peak brightness, as well as a goodness-of-fit parameter. Each fit is performed multiple times with different choices of filter bands and epoch range in order to quantify the systematic uncertainty on the fitted parameters. We use a parametric population model for the distribution of observed SN Ia parameters from large surveys, and extend it to represent red, dim, and bright outliers found in a low-redshift SN Ia data set. We discuss the potential uncertainties of this population model and find it to be reliable given the current uncertainties on cosmological parameters. Using our population model, we assign each set of fitted parameters a likelihood of being observed in nature, and a figure of merit based on this likelihood. We define a second figure of merit based on the quality of the light curve fit, and combine the two measures into an overall figure of merit for each explosion model. We compute figures of merit for a variety of one-, two-, and three-dimensional explosion models and show that our evaluation method allows meaningful inferences across a wide range of light curve quality and fitted parameters.

  1. Comparing eyewitness-derived trajectories of bright meteors to instrumentally-observed data

    NASA Astrophysics Data System (ADS)

    Moser, D. E.

    2017-09-01

    The NASA Meteoroid Environment Office (MEO) is often called upon to analyze meteors of public interest observed over the United States. Data from meteor networks are often utilized to accomplish this, as are recordings from the general public. When these methods fail, eyewitness reports are the only resource which can be leveraged. The MEO developed a tool to crudely calculate the trajectories of bright meteors from the eyewitness reports submitted to the American Meteor Society. The tool was tested on eyewitness data for 33 cases and compared to observed data from the NASA All Sky Fireball Network. The tool performed better for cases with more than 75 eyewitness reports than those with fewer than 75, by almost a factor of two across all metrics except for the end height. For these cases, the eyewitness-derived trajectory was about 50 km from the observed trajectory, the radiant was within 15°, and the speed was within 20% of that observed on average. A description of the tool, example case studies, and general trends are described.

  2. Ion cyclotron instability at Io: Hybrid simulation results compared to in situ observations

    NASA Astrophysics Data System (ADS)

    Šebek, Ondřej; Trávníček, Pavel M.; Walker, Raymond J.; Hellinger, Petr

    2016-08-01

    We present analysis of global three-dimensional hybrid simulations of Io's interaction with Jovian magnetospheric plasma. We apply a single-species model with simplified neutral-plasma chemistry and downscale Io in order to resolve the ion kinetic scales. We consider charge exchange, electron impact ionization, and photoionization by using variable rates of these processes to investigate their impact. Our results are in a good qualitative agreement with the in situ magnetic field measurements for five Galileo flybys around Io. The hybrid model describes ion kinetics self-consistently. This allows us to assess the distribution of temperature anisotropies around Io and thereby determine the possible triggering mechanism for waves observed near Io. We compare simulated dynamic spectra of magnetic fluctuations with in situ observations made by Galileo. Our results are consistent with both the spatial distribution and local amplitude of magnetic fluctuations found in the observations. Cyclotron waves, triggered probably by the growth of ion cyclotron instability, are observed mainly downstream of Io and on the flanks in regions farther from Io where the ion pickup rate is relatively low. Growth of the ion cyclotron instability is governed mainly by the charge exchange rate.

  3. Coronal Mass Ejections and Dimmings: A Comparative Study using MHD Simulations and SDO Observations

    NASA Astrophysics Data System (ADS)

    Jin, Meng; Cheung, Mark; DeRosa, Marc L.; Nitta, Nariaki; Schrijver, Karel

    2017-08-01

    Solar coronal dimmings have been observed extensively in the past two decades. Due to their close association with coronal mass ejections (CMEs), there is a critical need to improve our understanding of the physical processes that cause dimmings and determine their relationship with CMEs. In this study, we investigate coronal dimmings by combining simulation and observational efforts. By utilizing a data-driven global magnetohydrodynamics model (AWSoM: Alfven-wave Solar Model), we simulate coronal dimmings resulting from different CME energetics and flux rope configurations. We synthesize the emissions of different EUV spectral bands/lines and compare with SDO/AIA and EVE observations. A detailed analysis of simulation and observation data suggests that the “core” dimming is mainly caused by the mass loss from the CME, while the “remote” dimming could have a different origin (e.g., plasma heating). Moreover, the interaction between the erupting flux rope with different orientations and the global solar corona could significantly influence the coronal dimming patterns. Using metrics such as dimming depth, dimming slope, and recovery time, we investigate the relationship between dimmings and CME properties (e.g., CME mass, CME speed) in the simulation. Our result suggests that coronal dimmings encode important information about CMEs. We also discuss how our knowledge about solar coronal dimmings could be extended to the study of stellar CMEs.

  4. Quality standards for real-world research. Focus on observational database studies of comparative effectiveness.

    PubMed

    Roche, Nicolas; Reddel, Helen; Martin, Richard; Brusselle, Guy; Papi, Alberto; Thomas, Mike; Postma, Dirjke; Thomas, Vicky; Rand, Cynthia; Chisholm, Alison; Price, David

    2014-02-01

    Real-world research can use observational or clinical trial designs, in both cases putting emphasis on high external validity, to complement the classical efficacy randomized controlled trials (RCTs) with high internal validity. Real-world research is made necessary by the variety of factors that can play an important a role in modulating effectiveness in real life but are often tightly controlled in RCTs, such as comorbidities and concomitant treatments, adherence, inhalation technique, access to care, strength of doctor-caregiver communication, and socio-economic and other organizational factors. Real-world studies belong to two main categories: pragmatic trials and observational studies, which can be prospective or retrospective. Focusing on comparative database observational studies, the process aimed at ensuring high-quality research can be divided into three parts: preparation of research, analyses and reporting, and discussion of results. Key points include a priori planning of data collection and analyses, identification of appropriate database(s), proper outcomes definition, study registration with commitment to publish, bias minimization through matching and adjustment processes accounting for potential confounders, and sensitivity analyses testing the robustness of results. When these conditions are met, observational database studies can reach a sufficient level of evidence to help create guidelines (i.e., clinical and regulatory decision-making).

  5. Comparing a Carbon Budget for the Amazon Basin Derived from Aircraft Observations

    NASA Astrophysics Data System (ADS)

    Chow, V. Y.; Dayalu, A.; Wofsy, S. C.; Gerbig, C.

    2015-12-01

    We present and compare a carbon budget for the Brazilian Amazon Basin based on the Balanço Atmosférico Regional de Carbono na Amazônia (BARCA) aircraft program, which occurred in November 2008 & May 2009, to other published carbon budgets. In particular, we compare our budget and analysis to others also derived from aircraft observations. Using mesoscale meteorological fields from ECMWF and WRF, we drive the Stochastic Time-Inverted Lagrangian Transport (STILT) model and couple the footprint, or influence, to a biosphere model represented by the Vegetation Photosynthesis Respiration Model (VPRM). Since it is the main driver for the VPRM, we use observed shortwave radiation from towers in Brazil and French Guyana to examine the modeled shortwave radiation data from GL 1.2 (a global radiation model based on GOES 8 visible imagery), ECMWF, and WRF to determine if there are any biases in the modeled shortwave radiation output. We use WRF-STILT and ECMWF-STILT, GL 1.2 shortwave radiation, temperature, and vegetation maps (IGBP and SYNMAP) updated by landuse scenarios modeled by Sim Amazonia 2 and Sim Brazil, to compute hourly a priori CO2 fluxes by calculating Gross Ecosystem Exchange and Respiration for the 4 significant vegetation types across two (wet and dry) seasons as defined by 10-years of averaged TRIMM precipitation data. SF6 from stations and aircraft observations are used to determine the anthropogenic CO2 background and the lateral boundary conditions are taken from CarbonTracker2013B. The BARCA aircraft mixing ratios are then used as a top down constraint in an inversion framework that solves for the parameters controlling the fluxes for each vegetation type. The inversion provides scaling factors for GEE and R for each vegetation type in each season. From there, we derive a budget for the Basin and compare/contrast with other published basinwide CO2 fluxes.

  6. Polar-Region Distributions of Poynting Flux: Global Models Compared With Observations

    NASA Astrophysics Data System (ADS)

    Melanson, P. D.; Lotko, W.; Murr, D.; Gagne, J. R.; Wiltberger, M.; Lyon, J. G.

    2007-12-01

    Low-altitude distributions of electric potential, field-aligned current and Poynting flux derived from the Lyon- Fedder-Mobarry global simulation model of the magnetosphere are compared with distributions derived from SuperDARN, the Iridium satellite constellation, and the Weimer 2005 empirical model for a one-hour interval (1400-1500 UT) on 23 November 1999 during which the interplanetary magnetic field was steady and southward. Synthetic measurements along a pseudo-satellite track are also obtained from each distribution and compared with measurements from the DMSP F13 satellite. Previous studies of the event are supplemented here with updated simulation results for the electric potential and field-aligned currents, new simulation diagnostics for the Poynting flux incident on the ionosphere, and comparisons of observational and simulation results with the Weimer empirical model. The location and extent of the simulated Poynting fluxes that occur in the afternoon sector, between the Region-1 and 2 currents, are consistent with the observed and empirically modeled locations, but the magnitudes exhibit significant differences (locally up to ~100% both higher and lower). Elsewhere, the distribution of simulated fluxes more closely resembles the empirically modeled values than the observed ones and in general is greater in magnitude by about 100%. Additionally, the fraction of simulated Poynting flux that flow into the polar cap region (above 75 deg) is about one third of the total flowing into the ionosphere above 60 deg; a similar value is found for both the observed and the empirically modeled fluxes. The effect of including the parallel potential drop in the self-consistent mapping of electric potential between the ionosphere and inner boundary of the simulation domain is also examined. Globally the effect is small (< 5%); however, in regions where the field-aligned potential drop is appreciable, local changes of 100% or more are found in the magnitude of the

  7. Use of Preprocedural MDCT for Cardiac Implantable Electric Device Lead Extraction: Frequency of Findings That Change Management.

    PubMed

    Ehieli, Wendy L; Boll, Daniel T; Marin, Daniele; Lewis, Robert; Piccini, Jonathan P; Hurwitz, Lynne M

    2017-04-01

    Five percent of cardiac implantable electric devices (CIEDs) are removed each year. Percutaneous extraction is preferred but can be complicated if the leads adhere to the vasculature or perforate. The goal of this study is to assess the frequency of findings on dedicated MDCT that alter preprocedural planning for percutaneous CIED extraction. One hundred patients with CIEDs who underwent MDCT before percutaneous lead extraction were analyzed. Major findings that could preclude percutaneous removal, including lead course and termination, were distinguished from moderately significant findings that could alter but not preclude percutaneous removal, including endofibrosis of leads to the vasculature, lead termination abnormalities, central vein stenosis, or thrombus. Incidental findings were characterized separately. Findings were correlated with preprocedural decisions, the extraction procedure performed, and procedural outcomes. Twenty-six women and 74 men with 125 right ventricular leads, 84 right atrial leads, and 26 coronary venous leads were evaluated. Major findings were present in 7% of patients, including six patients with lead perforation and one with a lead coursing outside a tricuspid annuloplasty ring. Moderately significant findings of endothelial fibrosis were found in 78% of patients. The central veins were narrowed or occluded in 42% of patients, and thrombus was present in 2% of patients. Thirty-six percent of patients had incidental findings, and 4% of patients had unexpected findings requiring immediate inpatient attention. MDCT performed before CIED lead extraction is able to identify major and moderately significant findings that can alter either percutaneous extraction or preprocedural planning. The use of dedicated preprocedural MDCT can help to stratify patient risk, guide decision making by the proceduralist, and identify non-catheter-related findings that affect patient management.

  8. Accuracy of water-enema multidetector computed tomography (WE-MDCT) in colon cancer staging: a prospective study.

    PubMed

    Sibileau, E; Ridereau-Zins, Catherine; Vanel, D; Pavageau, A H; Bertrais, S; Metivier-Cesbron, E; Venara, A; Aubé, C

    2014-10-01

    To assess the accuracy of water-enema multidetector computed tomography (WE-MDCT) in extra-rectal colon cancer staging. Fifty-three patients (mean age 70 years) with extra-rectal colon cancer proven by colonoscopy and biopsy were prospectively evaluated by preoperative WE-MDCT. CT scans were both intraluminal (water enema or WE) and intravenous (iodinated) contrast enhanced (CE). All patients underwent surgery. Tumors were classified with the TNM staging system. Noted CT features were: tumor size and location; tumor form and edges; spread to the pericolic fat or neighboring organs; thickening of retroperitoneal fascia; number, size, and enhancement of the peritumoral lymph nodes. Tumors were classified on CT into 3 T-stage groups: T1/T2, T3, and T4. Lymph nodes were classified by their density after injection [positive over 100 Hounsfield units (HU)]. Tumor localization to the specific colon segment was correct in all the cases. The agreement between WE-MDCT staging and histopathology staging was good (k = 0.64). An irregular and bowl-shaped aspect of the external edges of tumor provided excellent sensitivity for T3/T4 inclusion (Se 97.7%, NPV 85.7%). Thickening of a fascia or the abdominal wall provided good specificity for T4 stage (Sp 88.1%, NPV 94.9%). Enhancement over 100 HU of at least one peritumoral lymph node was the best criterion of N+ staging (Sp 67.7%, NPV 87.5%). WE-MDCT permits good staging of colon cancer based on objective features.

  9. [Dose reduction and image quality in MDCT of the upper abdomen: potential of an adaptive post-processing filter].

    PubMed

    Kröpil, P; Lanzman, R S; Walther, C; Röhlen, S; Godehardt, E; Mödder, U; Cohnen, M

    2010-03-01

    To evaluate the effects of a 2D non-linear adaptive post-processing filter (2D-NLAF) on image quality in dose-reduced multi-detector CT (MDCT) of the upper abdomen. MDCT of the upper abdomen was simulated on a 64-slice scanner using a multi-modal anthropomorphic phantom (CIRS, Norfolk, USA). While keeping the collimation (64 x 0.6 mm) and pitch (p = 1) unchanged, the tube current (100 - 500 mAs) and tube potential (80 - 140 kVp) were varied to perform MDCT as high dose (CTDI > 20), middle dose (CTDI 10 - 20) and low dose (CTDI < 10) level protocols. Four independent blinded radiologists evaluated axial images with a thickness of 7 and 3 mm with respect to the presentation of "mesenteric low contrast lesions", "liver veins", "liver cysts", "renal cysts" and "big vessels". The subjective image quality of original data and post-processed images using a 2D-NLAF (SharpViewCT, Linköping, Sweden) was graded on a 5-point scale (from "1" not visible to "5" excellent) and statistically analyzed. The effective dose (E) was estimated using commercial software (CT-EXPO). For all protocol groups, 2D-NLAF led to a significant improvement in subjective image quality for all examined lesions (p < 0.01), particularly at the protocols of middle dose (E: 5 - 8 mSv) and low dose level (E: 1 - 5 mSv). A maximum effect was seen in middle dose protocols for "low contrast lesions" (score "3.3" with filter versus "2.5" without) and "liver veins" ("4.5" versus "3.9"). The phantom study indicates a potential dose reduction of up to 50 % in MDCT of the upper abdomen by use of a 2D-NLAF, which should be further examined in clinical trails. Georg Thieme Verlag KG Stuttgart New York.

  10. [Evaluation of left ventricular function with a 16-slice multidetector tomograph (MDCT-16): correlation with cardiovascular magnetic resonance imaging].

    PubMed

    de la Peña-Almaguer, Erasmo; Azpiri López, José Ramón; González-Camid, Felipe de Jesús; Ponce de León, Enrique; Flores-Ramírez, Ramiro; Zamarripa, Rafael; Loera, Javier; Rodríguez, Daniel; González Quijano, Rafael; Azpiri-Magallanes, Marcela; Jaramillo Estrada, Samuel; Assad Morell, José Luis

    2005-01-01

    The evaluation of Left ventricular function has both prognostic as well as therapeutic implications in patients with heart disease. Non-invasive coronary angiography with computed tomography using 16 slices (MDCT-16) allows to obtain images of the coronary anatomy due to its high spatial and temporal resolution, and also, to obtain data regarding Left ventricular function. The objective of this study was to correlate the use of MDCT-16 for the evaluation of the Left ventricular parameters using MRI as the Standard of reference. MRI: Se A 1.5 Tesla GE CvI Scanner optimized for cardiovascular applications was used. Using an ECG gated steady state fast precession sequence (SSFP, Thickness 10 mm, Flip Angle 45, FOV 36 cm. NEX 1, Frequency 256, Phase 128, Partial FOV 0.75, 16VPS), 6 to 8 short axis images of from base to apex of the left ventricle were obtained. Tomography: Using a 16 slice Multidetector tomograph (GE Lightspeed) and using ECG synchronization, images of the heart were obtained after the administration of 80 mls. of no-ionic contrast. The images were reconstructed off-line to obtain from 6 to 8 slices in a similar fashion to that of MR. Both studies were independently analyzed by 2 operators who obtained the ventricular function data. Linear correlation and a Paired T Student test was used to analyze the data and was considered significant when p < 0.05. 20 consecutive patients were evaluated with MDCT-16 and MRI, 18 males, mean age 52 +/- 15 years. There was no significant difference among the measurements for cardiac CT and MRI of the end-diastolic volume (EDV) and end-sistolic volume (ESV), stroke volume (SV), LV Mass or LV ejection fraction (LVEF). This results show a high correlation among the clinically relevant ventricular function parameters evaluated by cardiovascular CT and MRI. This findings suggest that ventricular function can be successfully evaluated along with the coronary anatomy using MDCT-16.

  11. Comparing Simulations and Observations of Galaxy Evolution: Methods for Constraining the Nature of Stellar Feedback

    NASA Astrophysics Data System (ADS)

    Hummels, Cameron

    Computational hydrodynamical simulations are a very useful tool for understanding how galaxies form and evolve over cosmological timescales not easily revealed through observations. However, they are only useful if they reproduce the sorts of galaxies that we see in the real universe. One of the ways in which simulations of this sort tend to fail is in the prescription of stellar feedback, the process by which nascent stars return material and energy to their immediate environments. Careful treatment of this interaction in subgrid models, so-called because they operate on scales below the resolution of the simulation, is crucial for the development of realistic galaxy models. Equally important is developing effective methods for comparing simulation data against observations to ensure galaxy models which mimic reality and inform us about natural phenomena. This thesis examines the formation and evolution of galaxies and the observable characteristics of the resulting systems. We employ extensive use of cosmological hydrodynamical simulations in order to simulate and interpret the evolution of massive spiral galaxies like our own Milky Way. First, we create a method for producing synthetic photometric images of grid-based hydrodynamical models for use in a direct comparison against observations in a variety of filter bands. We apply this method to a simulation of a cluster of galaxies to investigate the nature of the red-sequence/blue-cloud dichotomy in the galaxy color-magnitude diagram. Second, we implement several subgrid models governing the complex behavior of gas and stars on small scales in our galaxy models. Several numerical simulations are conducted with similar initial conditions, where we systematically vary the subgrid models, afterward assessing their efficacy through comparisons of their internal kinematics with observed systems. Third, we generate an additional method to compare observations with simulations, focusing on the tenuous circumgalactic

  12. A comparative study between a high-gain interconnected observer and an adaptive observer applied to IM-based WECS

    NASA Astrophysics Data System (ADS)

    Naifar, Omar; Boukettaya, Ghada; Oualha, Abdelmajid; Ouali, Abderrazak

    2015-05-01

    This paper is devoted to the investigation of the potentialities of induction motor sensorless strategies in speed control applications. A comparison study is carried out between two observation approaches dedicated to speed control strategies of induction machine (IM)-based wind energy conversion systems (WECS) under parametric variations, such as: i) the adaptive observer approach, which is based on the speed adaptation law and ii) the interconnected observer, that offers robustness and stability of the system with reduced CPU time. The comparison study is achieved considering four performance criteria: stability, robustness with respect to the variations of the machine inductances, robustness with respect to the variations of the machine resistances, feasibility of the torque estimation. It has been found that the introduced interconnected observer exhibits a higher performance than the traditional adaptive one, with respect to the above-cited comparison criteria.

  13. Comparing ED(MF)n in the gray zone to observations

    NASA Astrophysics Data System (ADS)

    Brast, Maren; Schemann, Vera; Moseley, Christopher; Crewell, Susanne; Neggers, Roel

    2017-04-01

    A new scale-adaptive shallow cumulus parameterization scheme is confronted with measurements made during the High Definition Clouds and Precipitation for advancing Climate Prediction Observational Prototype Experiment (HOPE) at the Jülich Observatory for Cloud Evolution (JOYCE). The Eddy-Diffusivity Multiple Mass-Flux (or ED(MF)n) scheme is a bin-macrophysics scheme, in which subgrid transport and clouds are formulated in terms of discretized size densities. It is implemented into a large-eddy simulation (LES) model, replacing the original subgrid transport scheme. This way the ED(MF)n can be tested in an idealized setting, covering the boundary layer gray zone. The LES is driven with large-scale forcings derived from analyses of the weather prediction model COSMO-DE, resulting in a reasonably accurate simulation of the measured conditions. During the HOPE campaign the boundary layer was measured extensively, supplying a wealth of data that can be used to evaluate parameterizations. Both long-term averages and individual shallow cumulus days are investigated. The LES is run with and without ED(MF)n for various resolutions, and the modeled boundary layer is compared to the observations from HOPE. This allows investigating the question how well the scale-adaptive scheme reproduces simulated and observed meteorology across the gray zone.

  14. A Hierarchical and Dynamic Seascape Framework for Scaling and Comparing Ocean Biodiversity Observations

    NASA Astrophysics Data System (ADS)

    Kavanaugh, M.; Muller-Karger, F. E.; Montes, E.; Santora, J. A.; Chavez, F.; Messié, M.; Doney, S. C.

    2016-02-01

    The pelagic ocean is a complex system in which physical, chemical and biological processes interact to shape patterns on multiple spatial and temporal scales and levels of ecological organization. Monitoring and management of marine seascapes must consider a hierarchical and dynamic mosaic, where the boundaries, extent, and location of features change with time. As part of a Marine Biodiversity Observing Network demonstration project, we conducted a multiscale classification of dynamic coastal seascapes in the northeastern Pacific and Gulf of Mexico using multivariate satellite and modeled data. Synoptic patterns were validated using mooring and ship-based observations that spanned multiple trophic levels and were collected as part of several long-term monitoring programs, including the Monterey Bay and Florida Keys National Marine Sanctuaries. Seascape extent and habitat diversity varied as a function of both seasonal and interannual forcing. We discuss the patterns of in situ observations in the context of seascape dynamics and the effect on rarefaction, spatial patchiness, and tracking and comparing ecosystems through time. A seascape framework presents an effective means to translate local biodiversity measurements to broader spatiotemporal scales, scales relevant for modeling the effects of global change and enabling whole-ecosystem management in the dynamic ocean.

  15. Observation of fresh Bos indicus embryos comparing stereoscopic and phase contrast microscopy.

    PubMed

    Gutiérrez, M E; Galina, C S; Moreno-Mendoza, N; Alarcón, M A; Godínez, B; Lammoglia, M A

    2014-05-01

    Summary The precision of embryo evaluation using stereoscopic microscopy (SM) and inverted phase contrast microscopy (PCM) was compared in 20 Bos indicus cows superovulated at two different times of the year. In total, 118 embryos were collected and classified according to their developmental stage and quality by two independent evaluators using SM and inverted PCM. Cohen's kappa coefficient was used to determine concordance between SM and PCM observations. A good level of agreement (k = 0.616) was found for quality level, and a moderate one (k = 0.464) for developmental stage, particularly at the morula stage. Using the TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labelling) technique, concordance level was deemed to be low with the SM (k = 0.169), and poor with the PCM (k = 0.217). Differences in concordance levels were also found between observations made at the two times of year, 78 embryos were evaluated in the rainy season when concordance level was good (k = 0.68), in contrast to the 40 embryos evaluated in the dry season when agreement was found to be poor (k = 0.24). In conclusion, inverted PCM was somewhat more effective for evaluating embryos, particularly at the morula stage. However, considering the high cost of an inverted PCM, the differences observed do not justify its purchase for routine embryo evaluation.

  16. Predictors of treatment with dialysis modalities in observational studies for comparative effectiveness research*

    PubMed Central

    Kuttykrishnan, Sooraj; Kalantar-Zadeh, Kamyar; Arah, Onyebuchi A.; Cheung, Alfred K.; Brunelli, Steve; Heagerty, Patrick J.; Katz, Ronit; Molnar, Miklos Z.; Nissenson, Allen; Ravel, Vanessa; Streja, Elani; Himmelfarb, Jonathan; Mehrotra, Rajnish

    2015-01-01

    Background The Institute of Medicine has identified the comparative effectiveness of renal replacement therapies as a kidney-related topic among the top 100 national priorities. Given the importance of ensuring internal and external validity, the goal of this study was to identify potential sources of bias in observational studies that compare outcomes with different dialysis modalities. Methods This observational cohort study used data from the electronic medical records of all patients that started maintenance dialysis in the calendar years 2007–2011 and underwent treatment for at least 60 days in any of the 2217 facilities operated by DaVita Inc. Each patient was assigned one of six dialysis modalities for each 91-day period from the date of first dialysis (thrice weekly in-center hemodialysis (HD), peritoneal dialysis (PD), less-frequent HD, home HD, frequent HD and nocturnal in-center HD). Results Of the 162 644 patients, 18% underwent treatment with a modality other than HD for at least one 91-day period. Except for PD, patients started treatment with alternative modalities after variable lengths of treatment with HD; the time until a change in modality was shortest for less-frequent HD (median time = 6 months) and longest for frequent HD (median time = 15 months). Between 30 and 78% of patients transferred to another dialysis facility prior to change in modality. Finally, there were significant differences in baseline and time-varying clinical characteristics associated with dialysis modality. Conclusions This analysis identified numerous potential sources of bias in studies of the comparative effectiveness of dialysis modalities. PMID:25883196

  17. STATIC VS PROSPECTIVE GATED, NON-BREATH HOLD VOLUMETRIC MDCT IMAGING OF THE LUNGS

    PubMed Central

    Saba, Osama I.; Chon, Deokiee; Beck, Kenneth; McLennan, Geoffrey; Sieren, Jered; Reinhardt, Joseph; Hoffman, Eric A.

    2005-01-01

    Rationale and Objectives: We seek to establish lung imaging methods which provide for the ability to image the lung under dynamic, non-breath hold conditions while providing “virtual breath hold,” quantifiable volumetric image data sets. We use static, breath hold images as the gold standard for evaluating these virtual breath hold images in both a phantom and sheep. Materials and Methods: We have developed axial methods for gating image acquisition to multiple points in the respiratory cycle interleaved with incremental table stepping during multidetector-row CT (MDCT) scanning. Datasets are generated over multiple breaths, providing volume images representative of multiple points within a respiratory cycle. To determine the reproducibility and accuracy of the methods , 6 anesthetized sheep were studied by MDCT in non-gated and airway-pressure (Pawy)-gated modes where Pawy was 0, 7 and 15 cmH2O. Results: No significant differences were found between the coefficient of variation in air volume measured from repeated static scans (1.74±1.78%), gated scans: Inspiratory gated (1.2±0.44%) or expiratory-gated (1.39±0.98%), or between static (1.74±1.78%) and gated (1.39+/-0.98%) scanning at similar Pawy (p>0.1). Measured air volumes were larger from static vs. gated scans by 5.85±3.77% at 7cmH2O and 4.45±3.6% at 15cmHL2O Pawy (p<0.05) consistent with hysteresis. Differences between air volumes at 7 and 15 cmH2O measured from either static or gated scans or that delivered by a supersyringe were insignificant (p<0.05). Visual accuracy of 3D anatomic geometry was achieved, and landmark certainty was within 1mm across respiratory cycles. Conclusion: A method has been demonstrated which provides for accurate gating to respiratory signals during axial scanning. High resolution volumetric image datasets are achievable while the scanned subject is breathing.Images are quantitatively similar to breath hold images with differences likely explained by known P-V hysteresis

  18. Using radiative kernels to compare feedback behavior over different time scales in CMIP output and observations

    NASA Astrophysics Data System (ADS)

    Shell, K. M.; Flink, M. M.; Jonko, A. K.

    2011-12-01

    Accurate climate projections require an understanding of feedback behavior on centennial timescales. Unfortunately, satellite and reanalysis observations are available only for the last few decades. We seek to determine the extent to which the relatively short observation-based records can constrain model estimates of long-term (century-scale) climate change in response to anthropogenic forcing. The radiative kernel technique allows us to study feedbacks related to temperature, water vapor, surface albedo, and clouds in a consistent fashion. We are using Coupled Model Intercomparison Project (CMIP) simulations to determine whether (modeled) feedbacks differ for interannual- and decadal-scale versus centennial-scale climate change. We also are comparing short-term feedbacks derived from satellite (Atmospheric Infrared Sounder, AIRS) and reanalysis (ERA-Interim) data with modeled feedbacks. We use two strategies. The first is the standard kernel technique where feedbacks are determined by differencing mean variables between two states. Preliminary work with CMIP3 indicates that averaging periods (e.g., 10 years versus 20 years) can change feedback estimates by more 20%. In general, we expect longer averaging periods to result in more accurate estimates of feedbacks. However, transient GCMs runs (as well as observational data sets) may be only a few decades long. In these cases, we must determine the best averaging period to balance the increase of noise caused by a shorter averaging period and the decrease of climate signal resulting from averaging periods that are closer together. To address this issue, the second strategy is a modified kernel technique where anomalies from the mean climate are combined with the kernel for every month of the time series. This technique is more appropriate in cases where there is not a large external forcing. We are calculating feedbacks in the CMIP5 simulations using both strategies with different averaging periods and start

  19. Morphological and functional MDCT: problem-solving tool and surrogate biomarker for hepatic disease clinical care and drug discovery in the era of personalized medicine.

    PubMed

    Wang, Liang

    2010-08-17

    This article explains the significant role of morphological and functional multidetector computer tomography (MDCT) in combination with imaging postprocessing algorithms served as a problem-solving tool and noninvasive surrogate biomarker to effectively improve hepatic diseases characterization, detection, tumor staging and prognosis, therapy response assessment, and novel drug discovery programs, partial liver resection and transplantation, and MDCT-guided interventions in the era of personalized medicine. State-of-the-art MDCT depicts and quantifies hepatic disease over conventional CT for not only depicting lesion location, size, and extent but also detecting changes in tumor biologic behavior caused by therapy or tumor progression before morphologic changes. Color-encoded parameter display provides important functional information on blood flow, permeability, leakage space, and blood volume. Together with other relevant biomarkers and genomics, the imaging modality is being developed and validated as a biomarker to early response to novel, targeted anti-VEGF(R)/PDGFR or antivascular/angiogenesis agents as its parameters correlate with immunohistochemical surrogates of tumor angiogenesis and molecular features of malignancies. MDCT holds incremental value to World Health Organization response criteria and Response Evaluation Criteria in Solid Tumors in liver disease management. MDCT volumetric measurement of future remnant liver is the most important factor influencing the outcome of patients who underwent partial liver resection and transplantation. MDCT-guided interventional methods deliver personalized therapies locally in the human body. MDCT will hold more scientific impact when it is fused with other imaging probes to yield comprehensive information regarding changes in liver disease at different levels (anatomic, metabolic, molecular, histologic, and other levels).

  20. An observational, prospective study comparing tibial and humeral intraosseous access using the EZ-IO.

    PubMed

    Ong, Marcus Eng Hock; Chan, Yiong Huak; Oh, Jen Jen; Ngo, Adeline Su-Yin

    2009-01-01

    Intraosseous (IO) access is an alternative to conventional intravenous access. The proximal tibia and proximal humerus have been proposed as suitable sites for IO access. A nonrandomized, prospective, observational study comparing flow rates and insertion success with tibial and humeral IO access in adults using the EZ-IO-powered drill device was conducted. The tibia was the first site of insertion, and a second IO was inserted in the humerus if clinically indicated for the same patient. Twenty-four patients were recruited, with 24 tibial and 11 humeral insertions. All EZ-IO insertions were successful at the first attempt except for 1 tibial insertion that was successful on the second attempt. All insertions were achieved within 20 seconds. Mean ease of IO insertion score (1=easiest to 10=most difficult) was 1.1 for both sites. We found tibial flow rates to be significantly faster using a pressure bag (165 mL/min) compared with those achieved without a pressure bag (73 mL/min), with a difference of 92 mL/min (95% confidence interval [CI]: 52, 132). Similarly, humeral flow rates were significantly faster using a pressure bag (153 mL/min) compared with humeral those achieved without pressure bag (84 mL/min), with a difference of 69 mL/min (95% CI: 39, 99). Comparing matched pairs (same patient), there was no significant difference in flow rates between tibial and humeral sites, with or without pressure bag infusion. Both sites had high-insertion success rates. Flow rates were significantly faster with a pressure bag infusion than without. However, we did not find any significant difference in tibial or humeral flow rates.

  1. Monitoring greenhouse gas emissions in Australian landscapes: Comparing ground based mobile surveying data to GOSAT observations

    NASA Astrophysics Data System (ADS)

    Bashir, S.; Iverach, C.; Kelly, B. F. J.

    2016-12-01

    Climate change is threatening the health and stability of the natural world and human society. Such concerns were emphasized at COP21 conference in Paris 2015 which highlighted the global need to improve our knowledge of sources of greenhouse gas and to develop methods to mitigate the effects of their emissions. Ongoing spatial and temporal measurements of greenhouse gases at both point and regional scales is important for clarification of climate change mechanisms and accounting. The Greenhouse gas Observing SATellite (GOSAT) is designed to monitor the global distribution of carbon dioxide (CO2) and methane (CH4) from orbit. As existing ground monitoring stations are limited and still unevenly distributed, satellite observations provide important frequent, spatially extensive, but low resolution observations. Recent developments in portable laser based greenhouse gas measurement systems have enabled the rapid measurement of greenhouse gases in ppb at the ground surface. This study was conducted to map major sources of CO2 and CH4 in the eastern states of Australia at the landscape scale and to compare the results to GOSAT observations. During April 2016 we conducted a regional CH4 and CO2 mobile survey, using an LGR greenhouse gas analyzer. Measurements were made along a 4000 KM circuit through major cities, country towns, dry sclerophyll forests, coastal wetlands, coal mining regions, coal seam gas developments, dryland farming and irrigated agricultural landscapes. The ground-based survey data were then compared with the data (L2) from GOSAT. Ground-based mobile surveys showed that there are clear statistical differences in the ground level atmospheric concentration of CH4 and CO2 associated with all major changes in land use. These changes extend for kilometers, and cover one or more GOSAT pixels. In the coal mining districts the ground-level atmospheric concentration of CH4 exceeded 2 ppm for over 40 km, yet this was not discernable in the retrieved data (L2

  2. Comparing satellite- to ground-based automated and manual cloud coverage observations - a case study

    NASA Astrophysics Data System (ADS)

    Werkmeister, A.; Lockhoff, M.; Schrempf, M.; Tohsing, K.; Liley, B.; Seckmeyer, G.

    2015-05-01

    In this case study we compare cloud fractional cover measured by radiometers on polar satellites (AVHRR) and on one geostationary satellite (SEVIRI) to ground-based manual (SYNOP) and automated observations by a cloud camera (Hemispherical Sky Imager, HSI). These observations took place in Hannover, Germany, and in Lauder, New Zealand, over time frames of 3 and 2 months, respectively. Daily mean comparisons between satellite derivations and the ground-based HSI found the deviation to be 6 ± 14% for AVHRR and 8 ± 16% for SEVIRI, which can be considered satisfactory. AVHRR's instantaneous differences are smaller (2 ± 22%) than instantaneous SEVIRI cloud fraction estimates (8 ± 29%) when compared to HSI due to resolution and scenery effect issues. All spaceborne observations show a very good skill in detecting completely overcast skies (cloud cover ≥ 6 oktas) with probabilities between 92 and 94% and false alarm rates between 21 and 29% for AVHRR and SEVIRI in Hannover, Germany. In the case of a clear sky (cloud cover lower than 3 oktas) we find good skill with detection probabilities between 72 and 76%. We find poor skill, however, whenever broken clouds occur (probability of detection is 32% for AVHRR and 12% for SEVIRI in Hannover, Germany). In order to better understand these discrepancies we analyze the influence of algorithm features on the satellite-based data. We find that the differences between SEVIRI and HSI cloud fractional cover (CFC) decrease (from a bias of 8 to almost 0%) with decreasing number of spatially averaged pixels and decreasing index which determines the cloud coverage in each "cloud-contaminated" pixel of the binary map. We conclude that window size and index need to be adjusted in order to improve instantaneous SEVIRI and AVHRR estimates. Due to its automated operation and its spatial, temporal and spectral resolution, we recommend as well that more automated ground-based instruments in the form of cloud cameras should be installed

  3. The GRACE Checklist: A Validated Assessment Tool for High Quality Observational Studies of Comparative Effectiveness.

    PubMed

    Dreyer, Nancy A; Bryant, Allison; Velentgas, Priscilla

    2016-10-01

    Recognizing the growing need for robust evidence about treatment effectiveness in real-world populations, the Good Research for Comparative Effectiveness (GRACE) guidelines have been developed for noninterventional studies of comparative effectiveness to determine which studies are sufficiently rigorous to be reliable enough for use in health technology assessments. To evaluate which aspects of the GRACE Checklist contribute most strongly to recognition of quality. We assembled 28 observational comparative effectiveness articles published from 2001 to 2010 that compared treatment effectiveness and/or safety of drugs, medical devices, and medical procedures. Twenty-two volunteers from academia, pharmaceutical companies, and government agencies applied the GRACE Checklist to those articles, providing 56 assessments. Ten senior academic and industry experts provided assessments of overall article quality for the purpose of decision support. We also rated each article based on the number of annual citations and impact factor of the journal in which the article was published. To identify checklist items that were most predictive of quality, classification and regression tree (CART) analysis, a binary, recursive, partitioning methodology, was used to create 3 decision trees, which compared the 56 article assessments with 3 external quality outcomes: (1) expert assessment of overall quality, (2) citation frequency, and (3) impact factor. A fourth tree looked at the composite outcome of all 3 quality indicators. The best predictors of quality included the following: use of concurrent comparators, limiting the study to new initiators of the study drug, equivalent measurement of outcomes in study groups, collecting data on most if not all known confounders or effect modifiers, accounting for immortal time bias in the analysis, and use of sensitivity analyses to test how much effect estimates depended on various assumptions. Only sensitivity analyses appeared consistently as

  4. Comparative Analyses of the CSSS Calculation in the UCSD Tomographic Solar Observations

    NASA Astrophysics Data System (ADS)

    Dunn, T.; Jackson, B. V.; Hick, P. P.; Buffington, A.; Zhao, X. P.

    2005-04-01

    We describe a new method to derive the interplanetary magnetic field (IMF) out to 1 AU from photospheric magnetic field measurements. The method uses photospheric magnetograms to calculate a source surface magnetic field at 15R⊙. Specifically, we use Wilcox Solar Observatory (WSO) magnetograms as input for the Stanford Current-Sheet Source-Surface (CSSS) model. Beyond the source surface the magnetic field is convected along velocity flow lines derived by a tomographic technique developed at UCSD and applied to interplanetary scintillation (IPS) observations. We compare the results with in situ data smoothed by an 18-h running mean. Radial and tangential magnetic field amplitudes fit well for the 20 Carrington rotations studied, which are largely from the active phase of the solar cycle. We show exemplary results for Carrington rotation 1965, which includes the Bastille Day event.

  5. Comparative observation of skeletal-dental abnormalities in wild, domestic, and laboratory rabbits.

    PubMed

    Okuda, Ayako; Hori, Yutaka; Ichihara, Nobutsune; Asari, Masao; Wiggs, Robert B

    2007-12-01

    Dietary habits must be considered as one of the major potential factors resulting in acquired malocclusions in rabbits. Although the dentition of the wild rabbit and the domesticated laboratory rabbit are basically identical, dietary habits are noticeably different. Therefore, the prevalence of tooth problems between these lagomorph species were investigated anatomically and radiographically. Mean measurements of the skull and dental arches suggested that wild rabbits have slightly shorter and wider skulls and dental arches compared with domestic laboratory rabbits. Root elongation of incisors and check teeth, and periodontal disease were more frequently observed in domestic laboratory rabbits. Diagnostic radiographs from domestic pet rabbits showed relatively higher crowns, severe root elongation, and advanced periodontitis. These results do not provide definitive evidence that dietary habits cause malocclusions, however they suggest that diet is a major factor in the initiation of malocclusions in rabbits.

  6. Comparability of patients with ANCA-associated vasculitis enrolled in clinical trials or in observational cohorts

    PubMed Central

    Pagnoux, Christian; Carette, Simon; Khalidi, Nader A.; Walsh, Michael; Hiemstra, Thomas F.; Cuthbertson, David; Langford, Carol; Hoffman, Gary S.; Koening, Curry L.; Monach, Paul A.; Moreland, Larry; Mouthon, Luc; Seo, Phil; Specks, Ulrich; Ytterberg, Steven; Westman, Kerstin; Hoglund, Peter; Harper, Lorraine; Flossmann, Oliver; Luqmani, Raashid; Savage, Caroline; Rasmussen, Niels; de Groot, Kirstin; Tesar, Vladimir; Jayne, David; Merkel, Pater A.; Guillevin, Loic

    2015-01-01

    Objective To analyse the differences between patients with granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) entered into randomised clinical trials (RCTs) and those followed in large observational cohorts. Methods The main characteristics and outcomes of patients with generalised and/or severe GPA or MPA with a five-factor score ≥1 enrolled in the French Vasculitis Study Group (FVSG) or the US-Canadian-based Vasculitis Clinical Research Consortium cohorts were compared to those enrolled in one of 2 FVSG clinical RCTs (WEG91, WEGENT) or 3 European Vasculitis Society clinical trials (CYCLOPS, CYCAZAREM, IMPROVE). Results 657 patients (65.3% with GPA) in RCTs were compared to 437 in cohorts (90.6% with GPA). RCT patients were older at diagnosis than the cohort patients (56.6±13.9 vs. 46.8±17.3 years), had higher Birmingham vasculitis activity score (19.5±9.1 vs. 16.9±7.4), and more frequent kidney disease (84.0% vs. 54.9%) but fewer ear, nose, and throat symptoms (56.8% vs. 72.2%). At 56 months post-diagnosis, mortality and relapse rates, adjusted for age and renal function, were higher for patients with GPA in RCTs vs. cohorts (10.7% vs. 2.5% [p=0.001] and 22.5% vs. 15.6% [p=0.03], respectively) but similar for patients with MPA (6.2% vs. 6.6% [p=0.92] and 16.6% vs. 10.1% [p=0.39], respectively). Conclusion Patients with GPA or MPA in RCTs and those in observational cohorts show important differences that should be remembered when interpreting results based on these study populations. PMID:26016754

  7. Statistical properties of a utility measure of observer performance compared to area under the ROC curve

    NASA Astrophysics Data System (ADS)

    Abbey, Craig K.; Samuelson, Frank W.; Gallas, Brandon D.; Boone, John M.; Niklason, Loren T.

    2013-03-01

    The receiver operating characteristic (ROC) curve has become a common tool for evaluating diagnostic imaging technologies, and the primary endpoint of such evaluations is the area under the curve (AUC), which integrates sensitivity over the entire false positive range. An alternative figure of merit for ROC studies is expected utility (EU), which focuses on the relevant region of the ROC curve as defined by disease prevalence and the relative utility of the task. However if this measure is to be used, it must also have desirable statistical properties keep the burden of observer performance studies as low as possible. Here, we evaluate effect size and variability for EU and AUC. We use two observer performance studies recently submitted to the FDA to compare the EU and AUC endpoints. The studies were conducted using the multi-reader multi-case methodology in which all readers score all cases in all modalities. ROC curves from the study were used to generate both the AUC and EU values for each reader and modality. The EU measure was computed assuming an iso-utility slope of 1.03. We find mean effect sizes, the reader averaged difference between modalities, to be roughly 2.0 times as big for EU as AUC. The standard deviation across readers is roughly 1.4 times as large, suggesting better statistical properties for the EU endpoint. In a simple power analysis of paired comparison across readers, the utility measure required 36% fewer readers on average to achieve 80% statistical power compared to AUC.

  8. Microphysical Simulations of Polar Stratospheric Clouds Compared with Calipso and MLS Observations

    NASA Astrophysics Data System (ADS)

    Zhu, Y.; Toon, O. B.; Kinnison, D. E.; Lambert, A.; Brakebusch, M.

    2014-12-01

    Polar stratospheric clouds (PSCs) form in the lower stratosphere during the polar night due to the cold temperature inside the polar vortex. PSCs are important to understand because they are responsible for the formation of the Antarctic ozone hole and the ozone depletion over the Arctic. In this work, we explore the formation and evolution of STS particles (Super-cooled Ternary Solution) and NAT (Nitric-acid Trihydrate) particles using the SD-WACCM/CARMA model. SD-WACCM/CARMA couples the Whole Atmosphere Community Climate Model using Specific Dynamics with the microphysics model (CARMA). The 2010-2011 Arctic winter has been simulated because the Arctic vortex remained cold enough for PSCs from December until the end of March (Manney et al., 2011). The unusual length of this cold period and the presence of PSCs caused strong ozone depletion. This model simulates the growth and evaporation of the STS particles instead of considering them as being in equilibrium as other models do (Carslaw et al., 1995). This work also explores the homogeneous nucleation of NAT particles and derives a scheme for NAT formation based on the observed denitrification during the winter 2010-2011. The simulated microphysical features (particle volumes, size distributions, etc.) of both STS (Supercooled Ternary Solutions) and NAT particles show a consistent comparison with historical observations. The modeled evolution of PSCs and gas phase ozone related chemicals inside the vortex such as HCl and ClONO2 are compared with the observations from MLS, MIPAS and CALIPSO over this winter. The denitrification history indicate the surface nucleation rate from Tabazadeh et al. (2002) removes too much HNO3 over the winter. With a small modification of the free energy term of the equation, the denitification and the PSC backscattering features are much closer to the observations. H2O, HCl, O3 and ClONO2 are very close to MLS and MIPAS observations inside the vortex. The model underestimates ozone

  9. Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise

    PubMed Central

    Brown, Patrick T.; Li, Wenhong; Cordero, Eugene C.; Mauget, Steven A.

    2015-01-01

    The comparison of observed global mean surface air temperature (GMT) change to the mean change simulated by climate models has received much public and scientific attention. For a given global warming signal produced by a climate model ensemble, there exists an envelope of GMT values representing the range of possible unforced states of the climate system (the Envelope of Unforced Noise; EUN). Typically, the EUN is derived from climate models themselves, but climate models might not accurately simulate the correct characteristics of unforced GMT variability. Here, we simulate a new, empirical, EUN that is based on instrumental and reconstructed surface temperature records. We compare the forced GMT signal produced by climate models to observations while noting the range of GMT values provided by the empirical EUN. We find that the empirical EUN is wide enough so that the interdecadal variability in the rate of global warming over the 20th century does not necessarily require corresponding variability in the rate-of-increase of the forced signal. The empirical EUN also indicates that the reduced GMT warming over the past decade or so is still consistent with a middle emission scenario's forced signal, but is likely inconsistent with the steepest emission scenario's forced signal. PMID:25898351

  10. Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise.

    PubMed

    Brown, Patrick T; Li, Wenhong; Cordero, Eugene C; Mauget, Steven A

    2015-04-21

    The comparison of observed global mean surface air temperature (GMT) change to the mean change simulated by climate models has received much public and scientific attention. For a given global warming signal produced by a climate model ensemble, there exists an envelope of GMT values representing the range of possible unforced states of the climate system (the Envelope of Unforced Noise; EUN). Typically, the EUN is derived from climate models themselves, but climate models might not accurately simulate the correct characteristics of unforced GMT variability. Here, we simulate a new, empirical, EUN that is based on instrumental and reconstructed surface temperature records. We compare the forced GMT signal produced by climate models to observations while noting the range of GMT values provided by the empirical EUN. We find that the empirical EUN is wide enough so that the interdecadal variability in the rate of global warming over the 20(th) century does not necessarily require corresponding variability in the rate-of-increase of the forced signal. The empirical EUN also indicates that the reduced GMT warming over the past decade or so is still consistent with a middle emission scenario's forced signal, but is likely inconsistent with the steepest emission scenario's forced signal.

  11. COMPARING THE OBSERVABLE PROPERTIES OF DWARF GALAXIES ON AND OFF THE ANDROMEDA PLANE

    SciTech Connect

    Collins, Michelle L. M.; Martin, Nicolas F.; Rich, R. M.; Ibata, Rodrigo A.; Chapman, Scott C.; McConnachie, Alan W.; Ferguson, Annette M.; Irwin, Michael J.; Lewis, Geraint F.

    2015-01-20

    The thin, extended planes of satellite galaxies detected around both the Milky Way and Andromeda are not a natural prediction of the Λ-cold dark matter paradigm. Galaxies in these distinct planes may have formed and evolved in a different way (e.g., tidally) from their off-plane neighbors. If this were the case, one would expect the on- and off-plane dwarf galaxies in Andromeda to have experienced different evolutionary histories, which should be reflected by the chemistries, dynamics, and star formation histories of the two populations. In this work, we present new, robust kinematic observations for two on-plane M31 dwarf spheroidal galaxies (And XVI and XVII) and compile and compare all available observational metrics for the on- and off-plane dwarfs to search for a signal that would corroborate such a hypothesis. We find that, barring their spatial alignment, the on- and off-plane Andromeda dwarf galaxies are indistinguishable from one another, arguing against vastly different formative and evolutionary histories for these two populations.

  12. The highs and lows of cloud radiative feedback: Comparing observational data and CMIP5 models

    NASA Astrophysics Data System (ADS)

    Jenney, A.; Randall, D. A.

    2014-12-01

    Clouds play a complex role in the climate system, and remain one of the more difficult aspects of the future climate to predict. Over subtropical eastern ocean basins, particularly next to California, Peru, and Southwest Africa, low marine stratocumulus clouds (MSC) help to reduce the amount of solar radiation that reaches the surface by reflecting incident sunlight. The climate feedback associated with these clouds is thought to be positive. This project looks at CMIP5 models and compares them to observational data from CERES and ERA-Interim to try and find observational evidence and model agreement for low, marine stratocumulus cloud feedback. Although current evidence suggests that the low cloud feedback is positive (IPCC, 2014), an analysis of the simulated relationship between July lower tropospheric stability (LTS) and shortwave cloud forcing in MSC regions suggests that this feedback is not due to changes in LTS. IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.

  13. Evaluation concepts to compare observed and simulated deposition areas of mass movements

    NASA Astrophysics Data System (ADS)

    Heiser, Micha; Scheidl, Christian; Kaitna, Roland

    2017-04-01

    A delineation of potentially endangered areas by geophysical mass flows, like debris flows, rock and snow avalanches, is an important for regional and urban planning. For this numerical simulation programs have become an important tool in engineering hazard assessment. However, when being confronted with the evaluation of model performance and sensitivity there are no standard, objective approaches. In this contribution we present a new approach to quantitatively compare 2D simulations of observed and simulated deposition patterns - a concept derived from a literature review of 75 peer reviewed articles which inverse modelled real events of different types of mass flows. It seems that existing evaluation concepts with respect to the deposition distribution does only account for one or a combination of two possible evaluation errors based on overestimation, underestimation and/or overlap of the simulation outcome with the observed reference. The proposed evaluation concept integrates all three possible errors and yields a single metric between -1 (no fit) and 1 (perfect fit). Combined with a ternary plot we further show that the proposed evaluation concept might act as a simple decision support tool to i) identify weaknesses and strengths of the simulation model, ii) to find the best simulation setup and iii) to test whether higher complexity of simulation models are balanced by higher accuracies. This method shall help developers and end-users of simulation models to better understand model behavior and provide a possibility for comparison of model results, independent of simulation platform and type of mass flow.

  14. Video techniques and data compared with observation in emergency trauma care

    PubMed Central

    Mackenzie, C; Xiao, Y

    2003-01-01

    Video recording is underused in improving patient safety and understanding performance shaping factors in patient care. We report our experience of using video recording techniques in a trauma centre, including how to gain cooperation of clinicians for video recording of their workplace performance, identify strengths of video compared with observation, and suggest processes for consent and maintenance of confidentiality of video records. Video records are a rich source of data for documenting clinician performance which reveal safety and systems issues not identified by observation. Emergency procedures and video records of critical events identified patient safety, clinical, quality assurance, systems failures, and ergonomic issues. Video recording is a powerful feedback and training tool and provides a reusable record of events that can be repeatedly reviewed and used as research data. It allows expanded analyses of time critical events, trauma resuscitation, anaesthesia, and surgical tasks. To overcome some of the key obstacles in deploying video recording techniques, researchers should (1) develop trust with video recorded subjects, (2) obtain clinician participation for introduction of a new protocol or line of investigation, (3) report aggregated video recorded data and use clinician reviews for feedback on covert processes and cognitive analyses, and (4) involve multidisciplinary experts in medicine and nursing. PMID:14645896

  15. Io's Volcanism: Thermo-Physical Models of Silicate Lava Compared with Observations of Thermal Emission

    NASA Technical Reports Server (NTRS)

    Davies, Ashely G.

    1996-01-01

    Analyses of thermal infrared outbursts from the jovian satellite Io indicate that at least some of these volcanic events are due to silicate lava. Analysis of the January 9, 1990 outburst indicates that this was an active eruption consisting of a large lava flow (with mass eruption rate of order 10(exp 5) cubic m/sec) and a sustained area at silicate liquidus temperatures. This is interpreted as a series of fire fountains along a rift zone. A possible alternative scenario is that of an overflowing lava lake with extensive fire fountaining. The January 9, 1990 event is unique as multispectral observations with respect to time were obtained. In this paper, a model is presented for the thermal energy lost by active and cooling silicate lava flows and lakes on Io. The model thermal emission is compared with Earth-based observations and Voyager IRIS data. The model (a) provides an explanation of the thermal anomalies on Io's surface; (b) provides constraints on flow behavior and extent and infers some flow parameters; and (c) determines flow geometry and change in flow size with time, and the temperature of each part of the flow or lava lake surface as a function of its age. Models of heat output from active lava flows or inactive but recently emplaced lava flows or overturning lava lakes alone are unable to reproduce the observations. If the January 9, 1990 event is the emplacement of a lava flow, the equivalent of 27 such events per year would yield a volume of material sufficient, if uniformly distributed, to resurface all of Io at a rate of 1 cm/year.

  16. Comparing Vesta's Surface Roughness to the Moon Using Bistatic Radar Observations by the Dawn Mission

    NASA Astrophysics Data System (ADS)

    Palmer, E. M.; Heggy, E.; Kofman, W. W.; Moghaddam, M.

    2015-12-01

    The first orbital bistatic radar (BSR) observations of a small body have been conducted opportunistically by NASA's Dawn spacecraft at Asteroid Vesta using the telecommunications antenna aboard Dawn to transmit and the Deep Space Network 70-meter antennas on Earth to receive. Dawn's high-gain communications antenna continuously transmitted right-hand circularly polarized radio waves (4-cm wavelength), and due to the opportunistic nature of the experiment, remained in a fixed orientation pointed toward Earth throughout each BSR observation. As a consequence, Dawn's transmitted radio waves scattered from Vesta's surface just before and after each occultation of the Dawn spacecraft behind Vesta, resulting in surface echoes at highly oblique incidence angles of greater than 85 degrees, and a small Doppler shift of ~2 Hz between the carrier signal and surface echoes from Vesta. We analyze the power and Doppler spreading of Vesta's surface echoes to assess surface roughness, and find that Vesta's area-normalized radar cross section ranges from -8 to -17 dB, which is notably much stronger than backscatter radar cross section values reported for the Moon's limbs (-20 to -35 dB). However, our measurements correspond to the forward scattering regime--such that at high incidence, radar waves are expected to scatter more weakly from a rough surface in the backscatter direction than that which is scattered forward. Using scattering models of rough surfaces observed at high incidence, we report on the relative roughness of Vesta's surface as compared to the Moon and icy Galilean satellites. Through this, we assess the dominant processes that have influenced Vesta's surface roughness at centimeter and decimeter scales, which are in turn applicable to assisting future landing, sampling and orbital missions of other small bodies.

  17. Correlation between epicardial adipose tissue and severity of coronary artery stenosis evaluated by 64-MDCT.

    PubMed

    Yang, Chunying; Li, Liang; Zha, Yunfei; Peng, Zhoufeng

    2016-01-01

    The purpose was to investigate the correlation between epicardial adipose tissue (EAT) thickness, EAT volume, and severity of coronary artery stenosis. We retrospectively enrolled 188 patients that underwent coronary computed tomography (CT) angiography for clinically suspected coronary artery disease using 64-MDCT. Images were reconstructed using a retrospective electrocardiogram-gated algorithm with 0.625-mm-thick sections. EAT thickness and volume were calculated. The coronary CT angiography showed 106 patients who had coronary artery pathology (178 lesions), 21 patients with moderate stenosis (27 lesions), 12 patients with severe stenosis (18 lesions), and 6 patients with complete occlusion (8 lesions). EAT thickness, EAT volume, and Gensini score were statistically different among groups (FT=32.306, FV=27.743, F=110.483, P=.000). Pearson correlation analysis showed that Gensini score had significantly positive correlation with EAT thickness and volume, respectively. EAT thickness and volume demonstrated a positive correlation with severity of coronary artery stenosis. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. A Numerical Study of Water Loss Rate Distributions in MDCT-based Human Airway Models

    PubMed Central

    Wu, Dan; Miyawaki, Shinjiro; Tawhai, Merryn H.; Hoffman, Eric A.; Lin, Ching-Long

    2015-01-01

    Both three-dimensional (3D) and one-dimensional (1D) computational fluid dynamics (CFD) methods are applied to study regional water loss in three multi-detector row computed-tomography (MDCT)-based human airway models at the minute ventilations of 6, 15 and 30 L/min. The overall water losses predicted by both 3D and 1D models in the entire respiratory tract agree with available experimental measurements. However, 3D and 1D models reveal different regional water loss rate distributions due to the 3D secondary flows formed at bifurcations. The secondary flows cause local skewed temperature and humidity distributions on inspiration acting to elevate the local water loss rate; and the secondary flow at the carina tends to distribute more cold air to the lower lobes. As a result, the 3D model predicts that the water loss rate first increases with increasing airway generation, and then decreases as the air approaches saturation, while the 1D model predicts a monotonic decrease of water loss rate with increasing airway generation. Moreover, the 3D (or 1D) model predicts relatively higher water loss rates in lower (or upper) lobes. The regional water loss rate can be related to the non-dimensional wall shear stress (τ*) by the non-dimensional mass transfer coefficient (h0*) as h0* = 1.15 τ*0.272, R = 0.842. PMID:25869455

  19. Effect of accreditation on the quality of chronic disease management: a comparative observational study.

    PubMed

    van Doorn-Klomberg, Arna L; Braspenning, Jozé C C; Wolters, René J; Bouma, Margriet; Wensing, Michel

    2014-11-04

    Practice accreditation is widely used to assess and improve quality of healthcare providers. Little is known about its effectiveness, particularly in primary care. In this study we examined the effect of accreditation on quality of care regarding diabetes, chronic obstructive pulmonary disease (COPD) and cardiovascular disease (CVD). A comparative observational study with two cohorts was performed. We included 138 Dutch family practices that participated in the national accreditation program for primary care. A first cohort of 69 practices was measured at start and completion of a 3-year accreditation program. A second cohort of 69 practices was included and measured simultaneously with the final measurement of the first cohort. In separate multilevel regression analyses, we compared both within-group changes in the first cohort and between-groups differences at follow-up (first cohort) and start (second cohort). Outcome measures consisted of 24 systematically developed indicators of quality of care in targeted chronic diseases. In the within-group comparison, we found improvements on 6 indicators related to diabetes (feet examination, cholesterol measurement, lipid lowering medication prescription) and COPD (spirometry performance, stop smoking advice). In the between-groups comparison we found that first cohort practices performed better on 4 indicators related to diabetes (cholesterol outcome) and CVD (blood pressure outcome, smoke status registration, glucose measurement). Improvements of the quality of primary care for patients with chronic diseases were found, but few could be attributed to the accreditation program. Further development of accreditation is needed to enhance its effectiveness on chronic disease management.

  20. Comparing human observer performance in detecting microcalcifications with energy weighting and photon counting breast CT

    NASA Astrophysics Data System (ADS)

    Kalluri, Kesava; Mahd, Mufeed; Glick, Stephen J.

    2012-03-01

    Breast CT (BCT) using a photon counting detector (PCD) has a number of advantages that can potentially improve clinical performance. Previous computer simulation studies showed that the signal to noise ratio (SNR) for microcalcifications is higher with energy weighted photon counting BCT as compared to cesium iodide energy integrating detector (CsI-EID) based BCT. CsI-EID inherently weighs the incident x-ray photons in direct proportion to the energy (contradicting the information content) which is not an optimal approach. PCD do not inherently weigh the incident photons. By choosing optimal energy weights, higher SNR can be achieved for microcalcifications and hence better detectability. In this simulation study, forward projection data of a numerical breast phantom with microcalcifications inserted were acquired using CsI-EID and PCD. The PCD projections were optimally weighed, and reconstructed using filtered back-projection. We compared observer performance in identifying microcalcifications in the reconstructed images using ROC analysis. ROC based results show that the average area(s) under curve(s) (AUC) for AUCPCD based methods are higher than the average AUCCsI-EID method.

  1. Pregnancy outcome following gestational exposure to TNF-alpha-inhibitors: a prospective, comparative, observational study.

    PubMed

    Diav-Citrin, Orna; Otcheretianski-Volodarsky, Anna; Shechtman, Svetlana; Ornoy, Asher

    2014-01-01

    To evaluate pregnancy safety of anti-TNF-α medications. Prospective, comparative, observational study done at the Israeli Teratology Information Service between 2002 and 2011. 83 anti-TNF-α-exposed-pregnancies (97.6% in the first trimester, T1) were followed-up and compared with 86 disease-matched (DM) and 341 non-teratogenic-exposed (NTE) pregnancies. The anti-TNF-α group consisted of 35 infliximab-, 25 etanercept-, and 23 adalimumab-exposed pregnancies. The rate of major congenital anomalies did not significantly differ between the three groups [3/65 (4.6%) (anti-TNF-α, T1), 5/79 (6.3%) (DM), 8/336 (2.4%) (NTE)], even after excluding genetic or cytogenetic anomalies [3/65 (4.6%) (anti-TNF-α, T1), 4/79 (5.1%) (DM), 6/336 (1.8%) (NTE)]. There were no cases of VATER/VACTERL association. The present study suggests that anti-TNF-α treatment does not pose a major teratogenic risk in humans. This conclusion is based on relatively small numbers of exposed pregnancies and should be interpreted with caution. Larger studies are needed to establish anti-TNF-α pregnancy safety. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Pregnancy outcome following in utero exposure to hydroxychloroquine: a prospective comparative observational study.

    PubMed

    Diav-Citrin, Orna; Blyakhman, Shani; Shechtman, Svetlana; Ornoy, Asher

    2013-08-01

    To evaluate pregnancy safety of hydroxychloroquine (HCQ) for rheumatologic diseases. Prospective comparative observational study done at the Israeli teratology information service between 1998 and 2006. 114 HCQ-exposed pregnancies (98.2% in the first trimester, T1) were followed-up and compared with 455 pregnancies of women counseled for non-teratogenic exposure. The difference in the rate of congenital anomalies was not statistically significant [7/97 (7.2%) vs. 15/440 (3.4%), p=0.094]. The analysis was repeated among those exposed in T1 excluding genetic or cytogenetic anomalies or congenital infections [5/95 (5.3%) vs. 14/440 (3.2%), p=0.355]. There were no cases of neonatal lupus erythematosus. The gestational age at delivery was earlier, rate of preterm delivery higher, and birth weight lower, in the HCQ group. The present study suggests that HCQ treatment in pregnancy is not a major human teratogen. The earlier gestational age and lower birth weight might be associated with maternal disease. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Potential for observing and discriminating impact craters and comparable volcanic landforms on Magellan radar images

    NASA Technical Reports Server (NTRS)

    Ford, J. P.

    1989-01-01

    Observations of small terrestrial craters by Seasat synthetic aperture radar (SAR) at high resolution (approx. 25 m) and of comparatively large Venusian craters by Venera 15/16 images at low resolution (1000 to 2000 m) and shorter wavelength show similarities in the radar responses to crater morphology. At low incidence angles, the responses are dominated by large scale slope effects on the order of meters; consequently it is difficult to locate the precise position of crater rims on the images. Abrupt contrasts in radar response to changing slope (hence incidence angle) across a crater produce sharp tonal boundaries normal to the illumination. Crater morphology that is radially symmetrical appears on images to have bilateral symmetry parallel to the illumination vector. Craters are compressed in the distal sector and drawn out in the proximal sector. At higher incidence angles obtained with the viewing geometry of SIR-A, crater morphology appears less compressed on the images. At any radar incidence angle, the distortion of a crater outline is minimal across the medial sector, in a direction normal to the illumination. Radar bright halos surround some craters imaged by SIR-A and Venera 15 and 16. The brightness probably denotes the radar response to small scale surface roughness of the surrounding ejecta blankets. Similarities in the radar responses of small terrestrial impact craters and volcanic craters of comparable dimensions emphasize the difficulties in discriminating an impact origin from a volcanic origin in the images. Similar difficulties will probably apply in discriminating the origin of small Venusian craters, if they exist. Because of orbital considerations, the nominal incidence angel of Magellan radar at the center of the imaging swath will vary from about 45 deg at 10 deg N latitude to about 16 deg at the north pole and at 70 deg S latitude. Impact craters and comparable volcanic landforms will show bilateral symmetry parallel to the illumination

  4. Creating a Common Data Model for Comparative Effectiveness with the Observational Medical Outcomes Partnership

    PubMed Central

    Resnic, F.S.; Robbins, S.L.; Denton, J.; Nookala, L.; Meeker, D.; Ohno-Machado, L.; Matheny, M.E.

    2015-01-01

    Summary Background Adoption of a common data model across health systems is a key infrastructure requirement to allow large scale distributed comparative effectiveness analyses. There are a growing number of common data models (CDM), such as Mini-Sentinel, and the Observational Medical Outcomes Partnership (OMOP) CDMs. Objectives In this case study, we describe the challenges and opportunities of a study specific use of the OMOP CDM by two health systems and describe three comparative effectiveness use cases developed from the CDM. Methods The project transformed two health system databases (using crosswalks provided) into the OMOP CDM. Cohorts were developed from the transformed CDMs for three comparative effectiveness use case examples. Administrative/billing, demographic, order history, medication, and laboratory were included in the CDM transformation and cohort development rules. Results Record counts per person month are presented for the eligible cohorts, highlighting differences between the civilian and federal datasets, e.g. the federal data set had more outpatient visits per person month (6.44 vs. 2.05 per person month). The count of medications per person month reflected the fact that one system’s medications were extracted from orders while the other system had pharmacy fills and medication administration records. The federal system also had a higher prevalence of the conditions in all three use cases. Both systems required manual coding of some types of data to convert to the CDM. Conclusions The data transformation to the CDM was time consuming and resources required were substantial, beyond requirements for collecting native source data. The need to manually code subsets of data limited the conversion. However, once the native data was converted to the CDM, both systems were then able to use the same queries to identify cohorts. Thus, the CDM minimized the effort to develop cohorts and analyze the results across the sites. PMID:26448797

  5. EuroInf: a multicenter comparative observational study of apomorphine and levodopa infusion in Parkinson's disease.

    PubMed

    Martinez-Martin, Pablo; Reddy, Prashanth; Katzenschlager, Regina; Antonini, Angelo; Todorova, Antoniya; Odin, Per; Henriksen, Tove; Martin, Anne; Calandrella, Daniela; Rizos, Alexandra; Bryndum, Narissah; Glad, Arne; Dafsari, Haidar Salimi; Timmermann, Lars; Ebersbach, Georg; Kramberger, Milica G; Samuel, Michael; Wenzel, Karoline; Tomantschger, Volker; Storch, Alexander; Reichmann, Heinz; Pirtosek, Zvezdan; Trost, Maja; Svenningsson, Per; Palhagen, Sven; Volkmann, Jens; Chaudhuri, K Ray

    2015-04-01

    Subcutaneous apomorphine infusion (Apo) and intrajejunal levodopa infusion (IJLI) are two treatment options for patients with advanced Parkinson's disease (PD) and refractory motor complications, with varying cost of treatment. There are no multicenter studies comparing the effects of the two strategies. This open-label, prospective, observational, 6-month, multicenter study compared 43 patients on Apo (48.8% males, age 62.3 ± 10.6 years; disease duration: 14 ± 4.4 years; median H & Y stage 3; interquartile range [IQR]: 3-4) and 44 on IJLI (56.8% males, age 62.7 ± 9.1 years; disease duration: 16.1 ± 6.7 years; median H & Y stage 4; IQR, 3-4). Cohen's effect sizes (≥0.8 considered as large) were "large" with both therapies with respect to total motor, nonmotor, and quality-of-life scores. The Non-Motor Symptoms Scale (NMSS) with Apo showed moderate improvement, whereas sleep/fatigue, gastrointestinal, urinary, and sexual dimensions of the NMSS showed significantly higher improvement with IJLI. Seventy-five percent on IJLI improved in their quality-of-life and nonmotor symptoms (NMS), whereas in the Apo group, a similar proportion improved in quality of life, but 40% in NMS. Adverse effects included peritonitis with IJLI and skin nodules on Apo. Based on this open-label, nonrandomized, comparative study, we report that, in advanced Parkinson's patients, both IJLI and Apo infusion therapy appear to provide a robust improvement in motor symptoms, motor complications, quality-of-life, and some NMS. Controlled, randomized studies are required.

  6. In multiple situational light settings, visual observation for skin colour assessment is comparable with colorimeter measurement.

    PubMed

    Wright, C Y; Wilkes, M; du Plessis, J L; Reeder, A I; Albers, P N

    2016-08-01

    Finding inexpensive and reliable techniques for assessing skin colour is important, given that it is related to several adverse human health outcomes. Visual observation is considered a subjective approach assessment and, even when made by trained assessor, concern has been raised about the need for controlled lighting in the study venue. The aim of this study is to determine whether visual skin colour assessments correlate with objective skin colour measurements in study venues with different lighting types and configurations. Two trained investigators, with confirmed visual acuity, visually classified the inner, upper arm skin colour of 556 adults using Munsell(®) colour classifications converted to Individual Typology Angle (°ITA) values based on published data. Skin colour at the same anatomic site was also measured using a colorimeter. Each participant was assessed in one of 10 different buildings, each with a different study day. Munsell(®) -derived °ITA values were compared to colorimeter °ITA values for the full sample and by building/day. We found a strong positive, monotonic correlation between Munsell(®) derived °ITA values and colorimeter °ITA values for all participants (Spearman ρ = 0.8585, P < 0.001). Similar relationships were found when Munsell(®) and colorimeter °ITA values were compared for participants assessed in the same building for all 10 buildings (Spearman ρ values ranged from 0.797 to 0.934, all correlations were statistically significant at P < 0.001). It is possible to visually assess individual skin colour in multiple situational lighting settings and retrieve results that are comparable with objective measurements of skin colour. This was true for individuals of varying population groups and skin pigmentation. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. Methodological Challenges When Comparing Demographic and Clinical Characteristics of International Observational Registries.

    PubMed

    Verstappen, Suzanne M M; Askling, Johan; Berglind, Niklas; Franzen, Stefan; Frisell, Thomas; Garwood, Christopher; Greenberg, Jeffrey D; Holmqvist, Marie; Horne, Laura; Lampl, Kathy; Michaud, Kaleb; Nyberg, Fredrik; Pappas, Dimitrios A; Reed, George; Symmons, Deborah P M; Tanaka, Eiichi; Tran, Trung N; Yamanaka, Hisashi; Ho, Meilien

    2015-12-01

    Comparisons of data from different registries can be helpful in understanding variations in many aspects of rheumatoid arthritis (RA). The study aim was to assess and improve the comparability of demographic, clinical, and comorbidity data from 5 international RA registries. Using predefined definitions, 2 subsets of patients (main cohort and subcohort) from 5 international observational registries (Consortium of Rheumatology Researchers of North America Registry [CORRONA], the Swedish Rheumatology Quality of Care Register [SRR], the Norfolk Arthritis Register [NOAR], the Institute of Rheumatology Rheumatoid Arthritis cohort [IORRA], and CORRONA International) were evaluated and compared. Patients ages >18 years with RA, and present in or recruited to the registry from January 1, 2000, were included in the main cohort. Patients from the main cohort with positive rheumatoid factor and/or erosive RA who had received ≥1 synthetic disease-modifying antirheumatic drug (DMARD), and switched to or added another DMARD, were included in the subcohort at time of treatment switch. Age and sex distributions were fairly similar across the registries. The percentage of patients with a high Disease Activity Score in 28 joints score varied between main cohorts (17.5% IORRA, 18.9% CORRONA, 24.7% NOAR, 27.7% CORRONA International, and 36.8% SRR), with IORRA, CORRONA, and CORRONA International including more prevalent cases of RA; the differences were smaller for the subcohort. Prevalence of comorbidities varied across registries (e.g., coronary artery disease ranged from 1.5% in IORRA to 7.9% in SRR), partly due to the way comorbidity data were captured and general cultural differences; the pattern was similar for the subcohorts. Despite different inclusion criteria for the individual RA registries, it is possible to improve the comparability and interpretability of differences across RA registries by applying well-defined cohort definitions. © 2015, American College of

  8. Visualisation of passive middle ear implants by cone beam and multi-detector computed tomography: a comparative in vitro study.

    PubMed

    Nguyen, T D; Kösling, S; Mlynski, R; Plontke, S K

    2016-12-01

    Modern passive middle ear titanium prostheses are filigree structures, resulting in poorer depiction on CT compared to prostheses used in the past. We compared the visibility of newer prostheses on cone beam CT (CBCT) to multi-detector CT (MDCT) with standard and lower dose in vitro, and analysed image noise and metal artefacts. Six different titanium middle ear prostheses (three partial and one total ossicular replacement prostheses, two stapes prostheses) were implanted twice in formalin-fixed head specimens-first correctly and then with displacement. Imaging was performed using standard CBCT and MDCT as well as MDCT with lower dose (36 single imaging investigations). Images were analysed with knowledge of the used types of middle ear prostheses, but blinded with respect to the positioning in the specific case. On all images the type of prostheses and their positions could be clearly recognized. Their identifiability including their details was rated as statistically significantly higher for all CBCT investigations than for MDCT. MDCT with lower dose showed the worst results. No statistical differences were found in image noise and metal artefacts. If available, CBCT should be preferred over MDCT in diagnostic evaluation of passive middle ear prostheses. • Middle ear prostheses became more filigree, leading to poorer visibility on CT. • High spatial resolution and paraxial reconstructions are necessary requirements for imaging evaluation. • CBCT and MDCT can identify type and positioning of titanium prostheses. • Metal artefacts play a minor part in filigree titanium prostheses. • Regarding visualisation of prostheses details, cone beam CT aids the evaluation.

  9. Scan time and patient dose for thoracic imaging in neonates and small children using axial volumetric 320-detector row CT compared to helical 64-, 32-, and 16- detector row CT acquisitions.

    PubMed

    Kroft, Lucia J M; Roelofs, Joost J H; Geleijns, Jacob

    2010-03-01

    Recently a 320-detector-row CT (MDCT) scanner has become available that allows axial volumetric scanning of a 16-cm-long range (50 cm field of view) in a single 0.35-s rotation. For imaging neonates and small children, volume scanning is potentially of great advantage as the entire scan range can be acquired in 0.35 s, which can reduce motion artefacts and may reduce the need for sedation in clinical CT imaging. Also, because there is no over-ranging associated with axial volumetric scanning, this may reduce patient radiation dose. To evaluate, by means of a phantom study, scan time and patient dose for thoracic imaging in neonates and small children by using axial cone-beam and helical fan-beam MDCT acquisitions. Paediatric imaging protocols were assessed for a 320-MDCT volumetric scanner (Aquilion ONE, Toshiba, Otawara, Japan). The 320-MDCT scanner allows for cone-beam acquisitions with coverage up to 160 mm, but it also allows for helical fan-beam acquisitions in 64-, 32-, or 16-MDCT modes. The acquisition configurations that were evaluated were 320 x 0.5 mm, 240 x 0.5 mm, and 160 x 0.5 mm for axial volumetric scanning, and 64 x 0.5 mm, 32 x 0.5 mm, and 16 x 0.5 mm for helical scanning. Dose assessment was performed for clinically relevant paediatric angiographic or chest/mediastinum acquisition protocols with tube voltages of 80 or 100 kVp and tube currents between 40 and 80 mA. Scan time was 0.35 s for 320-MDCT acquisitions, scan times varied between 1.9 s and 8.3 s for helical acquisitions. Dose savings varying between 18% and 40% were achieved with axial volumetric scanning as compared to helical scanning (for 320- versus 64-MDCT at 160 mm and 80 kVp, and for 320- versus 16-MDCT at 80 mm and 100 kVp, respectively). Statistically significant reduction in radiation dose was found for axial 320-MDCT volumetric scanning compared to helical 64-, 32-, and 16-MDCT scanning. Axial thoracic CT of neonates and small children with volumetric 320-MDCT can be performed

  10. Committing driving violations: an observational study comparing city, town and village.

    PubMed

    Rosenbloom, Tova; Ben-Eliyahu, Adar; Nemrodov, Dan; Biegel, Ariela; Perlman, Amotz

    2009-01-01

    This article compares observed driving behavior in a city, a town, and a village. Unobtrusive observations were made at intersections in each residential type. Five violation types were observed: (a) not wearing a seat belt (seat belt violation); (b) not using a safety seat for a child (safety seat violation for children); (c) not using a speaker while speaking on the phone (on-phone violation); (d) failing to comply with a 'give way' sign ('give way' sign violation); and (e) stopping in an undesignated area (undesignated stop violation). It was expected that in accordance with the anonymity hypothesis that the bigger residential areas' rate of traffic violations would be higher. The effects of the residential type, drivers' gender, and age were assessed using the multiple regression model. The stepwise method of evaluation was employed. The model converged on step 3 (Adjusted R square=0.039). Residential type and gender contributed significantly to the model. Consistent with prior research, male drivers committed more violations than female drivers. Chi-square analyses were used to test the distribution of violations by the settlement types. Overall, more drivers committed violations in the two small residential areas than in the city, with 30% of city drivers, 43% of town drivers, and 51% of village drivers committing at least one violation (chi2 (2)=37.65, p<0.001). Moreover, in the town and the village, a combination of one or more violations was committed more often than in the city(chi2 (1)=34.645, p<0.001). Accordingly, more drivers committed violations in the two small settlements (48.4%) than in the city (30.6%). Possible explanations for the observed results were provided in the Discussion section. The conclusions of this paper are that drivers in small villages tend to disobey traffic laws. Therefore, efforts have to be made in companies to take this issue in consideration while running fleets in companies located in small places far from the center.

  11. Borehole Temperature Observations Compared to Synthetic Subsurface Temperatures Generated by Proxy Climate Reconstructions

    NASA Astrophysics Data System (ADS)

    Huang, S.; Pollack, H. N.

    2002-12-01

    The array of proxy climate reconstructions for the Northern Hemisphere over the past millennium (Briffa and Osborn, Science 295, 2002) are all consistent in their representation of the 20th century warming, but diverge in their representations of the 11th through 19th centuries. The 'end-member' reconstructions of this array are represented by the MBH history (Mann, Bradley and Hughes, Geophys. Res. Lett. 26, 1999) which shows a slow cooling from 1000-1900, and the ECS history (Espers, Cook and Schweingruber, Science 295, 2002) which shows a net warming over much of that time interval. Temperature changes at the surface impose a downward-propagating thermal anomaly on the subsurface temperature field. Implicit in every proxy history of surface temperature is a subsurface temperature anomaly generated by the surface temperature model. We have calculated synthetic subsurface temperature anomalies for these 'end-member' proxy reconstructions, and compare the synthetic anomalies to borehole temperature observations. For this comparison we have selected 213 borehole sites, all logged in the 1990s and well-distributed longitudinally over the continents of the Northern Hemisphere. The synthetic subsurface temperature anomaly profile generated by the ECS reconstruction is close to the borehole observations, whereas the subsurface anomaly associated with the MBH reconstruction is significantly different. Because of its long multi-century cooling trend, the MBH model predicts a negative subsurface temperature anomaly below a depth of about 70m, a characteristic that is absent in both the ECS subsurface signature and in the borehole observations. We recognize that both the ECS reconstruction and the borehole temperatures are essentially extra-tropical records restricted to the continents, whereas the MBH reconstruction utilizes both tropical and extra-tropical data from both continents and oceans. However, to reconcile the significant difference between the negative

  12. THE STAR FORMATION RATE OF TURBULENT MAGNETIZED CLOUDS: COMPARING THEORY, SIMULATIONS, AND OBSERVATIONS

    SciTech Connect

    Federrath, Christoph; Klessen, Ralf S.

    2012-12-20

    The role of turbulence and magnetic fields is studied for star formation in molecular clouds. We derive and compare six theoretical models for the star formation rate (SFR)-the Krumholz and McKee (KM), Padoan and Nordlund (PN), and Hennebelle and Chabrier (HC) models, and three multi-freefall versions of these, suggested by HC-all based on integrals over the log-normal distribution of turbulent gas. We extend all theories to include magnetic fields and show that the SFR depends on four basic parameters: (1) virial parameter {alpha}{sub vir}; (2) sonic Mach number M; (3) turbulent forcing parameter b, which is a measure for the fraction of energy driven in compressive modes; and (4) plasma {beta}=2M{sub A}{sup 2}/M{sup 2} with the Alfven Mach number M{sub A}. We compare all six theories with MHD simulations, covering cloud masses of 300 to 4 Multiplication-Sign 10{sup 6} M{sub Sun} and Mach numbers M=3-50 and M{sub A}=1-{infinity}, with solenoidal (b = 1/3), mixed (b = 0.4), and compressive turbulent (b = 1) forcings. We find that the SFR increases by a factor of four between M=5 and 50 for compressive turbulent forcing and {alpha}{sub vir} {approx} 1. Comparing forcing parameters, we see that the SFR is more than 10 times higher with compressive than solenoidal forcing for M=10 simulations. The SFR and fragmentation are both reduced by a factor of two in strongly magnetized, trans-Alfvenic turbulence compared to hydrodynamic turbulence. All simulations are fit simultaneously by the multi-freefall KM and multi-freefall PN theories within a factor of two over two orders of magnitude in SFR. The simulated SFRs cover the range and correlation of SFR column density with gas column density observed in Galactic clouds, and agree well for star formation efficiencies SFE = 1%-10% and local efficiencies {epsilon} = 0.3-0.7 due to feedback. We conclude that the SFR is primarily controlled by interstellar turbulence, with a secondary effect coming from magnetic fields.

  13. The Star Formation Rate of Turbulent Magnetized Clouds: Comparing Theory, Simulations, and Observations

    NASA Astrophysics Data System (ADS)

    Federrath, Christoph; Klessen, Ralf S.

    2012-12-01

    The role of turbulence and magnetic fields is studied for star formation in molecular clouds. We derive and compare six theoretical models for the star formation rate (SFR)—the Krumholz & McKee (KM), Padoan & Nordlund (PN), and Hennebelle & Chabrier (HC) models, and three multi-freefall versions of these, suggested by HC—all based on integrals over the log-normal distribution of turbulent gas. We extend all theories to include magnetic fields and show that the SFR depends on four basic parameters: (1) virial parameter αvir (2) sonic Mach number {M}; (3) turbulent forcing parameter b, which is a measure for the fraction of energy driven in compressive modes; and (4) plasma \\beta =2 {M}_A^2/ {M}^2 with the Alfvén Mach number {M}_A. We compare all six theories with MHD simulations, covering cloud masses of 300 to 4 × 106 M ⊙ and Mach numbers {M}=3-50 and {M}_A=1-∞, with solenoidal (b = 1/3), mixed (b = 0.4), and compressive turbulent (b = 1) forcings. We find that the SFR increases by a factor of four between {M}=5 and 50 for compressive turbulent forcing and αvir ~ 1. Comparing forcing parameters, we see that the SFR is more than 10 times higher with compressive than solenoidal forcing for {M}=10 simulations. The SFR and fragmentation are both reduced by a factor of two in strongly magnetized, trans-Alfvénic turbulence compared to hydrodynamic turbulence. All simulations are fit simultaneously by the multi-freefall KM and multi-freefall PN theories within a factor of two over two orders of magnitude in SFR. The simulated SFRs cover the range and correlation of SFR column density with gas column density observed in Galactic clouds, and agree well for star formation efficiencies SFE = 1%-10% and local efficiencies epsilon = 0.3-0.7 due to feedback. We conclude that the SFR is primarily controlled by interstellar turbulence, with a secondary effect coming from magnetic fields.

  14. Comparing the relationships between aerosol optical depth and cloud properties in observations and global models

    NASA Astrophysics Data System (ADS)

    Gryspeerdt, Edward; Quaas, Johannes

    2016-04-01

    Aerosols impact the climate both directly, through their interaction with radiation and indirectly, via their ability to act as cloud condensation nuclei (CCN), modifying cloud properties. The influence of aerosols on cloud properties is highly uncertain. Many relationships between aerosol optical depth (AOD) and cloud properties have been observed using satellite data, but previous work has shown that some of these relationships are the product of the strong AOD-cloud fraction (CF) relationship. The confounding influence of local meteorology obscures the magnitude of any aerosol impact on CF, and so also the impact of aerosol on other cloud properties. For example, both AOD and CF are strongly influenced by relative humidity, which can generate a correlation between them. Previous studies have used reanalysis data to account for confounding meteorological variables. This requires knowledge of the relevant meteorological variables and is limited by the accuracy of the reanalysis data. Recent work has shown that by using the cloud droplet number concentration (CDNC) to mediate the AOD-CF relationship, the impact of relative humidity can be significantly reduced. This method removes the limitations imposed by the finite accuracy of reanalysis data. In this work we investigate the impact of the CDNC mediation on the AOD-CF relationship and on the relationship between AOD and other cloud properties in global atmospheric models. By comparing pre-industrial and present day runs, we investigate the success of the CDNC mediated AOD-CF relationship to predict the change in CF from the pre-industrial to the present day using only observations of the present day relationships between clouds and aerosol properties. This helps to determine whether the satellite-derived relationship provides a constraint on the aerosol indirect forcing due to changes in CF.

  15. Comparing and contrasting observed adaptations in three deltas: the Ganges-Meghna-Brahmaputra, Mahanadi and Volta

    NASA Astrophysics Data System (ADS)

    Nicholls, R. J.; Suckall, N.; Mensah, A.; Mondal, S.; Dey, S.; Hazra, S.

    2015-12-01

    In low and middle-income countries, many deltaic communities directly depend on the natural environment for income and well-being. Current environmental concerns that threaten deltaic communities, such as increasing salinity, sedimentation, erosion and subsidence are likely to be exacerbated by climate change and variability, for example sea-level rise, increased storminess and rising temperatures. Such changes, along with other social and environmental stressors, mean that communities must adapt. This paper outlines findings of a systematic review of the peer-reviewed and grey literature that examines observed adaptations in three deltas of differing sizes in various geographical contexts: the Ganges-Meghna-Brahmaputra in India and Bangladesh, the Mahanadi in India, and the Volta in Ghana. It compares and contrasts various elements of observed adaptations, including who is driving the adaptation, the beneficiaries, barriers to participation and evidence for maladaptation. The predominant drivers of adaptation vary from government (at state level in India and national level in Bangladesh) and NGOs (in Ghana). Autonomous adaptations are not widely reported in the literature from any of the deltas. In all three deltas there is a focus on supporting adaptation in farming rather than fishing; despite the fact that fisheries contribute to local food security as well as national economies. Lack of access to financial, natural, physical and human capital are common barriers to adaptation in all three deltas. Additionally the Indian literature in particular highlights the lack of coordination between different government departments, coupled with an excessively top-down (state-driven) approach to adaptation. Maladaptation is most commonly reported in the literature from Bangladesh, for example, loss of employment of inland fishermen in embanked areas. The paper concludes by highlighting some of the implications of these findings for adaptation policy in deltas.

  16. Coagulation Profile Dynamics in Pediatric Patients with Cushing Syndrome: A Prospective, Observational Comparative Study

    PubMed Central

    Birdwell, Leah; Lodish, Maya; Tirosh, Amit; Chittiboina, Prashant; Keil, Meg; Lyssikatos, Charlampos; Belyavskaya, Elena; Feelders, Richard A.; Stratakis, Constantine A.

    2016-01-01

    Objective To evaluate the association between Cushing syndrome and hypercoagulability in children. Study design A prospective, observational study was performed of 54 patients with Cushing syndrome, 15.1 ± 3.9 years, treated at the National Institutes of Health Clinical Center. Coagulation profiles were taken before and 6-12 months after surgery and compared with 18 normocortisolemic children, 13.7 ± 3.6 years. Results At baseline, patients with Cushing syndrome had greater levels of the procoagulant factor VIII (FVIII) vs controls (145 IU/dL ± 84 vs 99 ± 47, P = .04); 6-12 months after surgery, FVIII levels decreased to 111 ± 47, P = .05. Patients with Cushing syndrome had greater levels of the antifibrinolytic α2-antiplasmin, 96 ± 17% vs 82 ± 26%, P = .015. After surgery, antifibrinolytic α2-antiplasmin levels decreased to 82 ± 24%, P < .001. Anticoagulants were greater in patients with Cushing syndrome vs controls at baseline, including protein C (138 ± 41% vs 84 ± 25%, P < .001), protein S (94 ± 19% vs 74 ± 19%, P = .001), and antithrombin III (96 ± 18% vs 77 ± 13%, P < .0001). The 24-hour urinary free cortisol levels correlated positively with FVIII levels, r = 0.43, P = .004. Conclusion Children with Cushing syndrome had elevated procoagulants, antifibrinolytics, and anticoagulants at baseline compared with controls; normalization of coagulation measures was seen after surgical cure. Despite the increase in anticoagulants, hypercortisolemia is associated with a hypercoagulable state in children, as is the case in adults. This finding has potential implications for prevention of venous thromboembolism in children with Cushing syndrome. PMID:27496264

  17. A Proxy System Modeling Toolbox for Comparing Water Isotope Observations to Simulations

    NASA Astrophysics Data System (ADS)

    Dee, S. G.; Emile-Geay, J.; Evans, M. N.; Noone, D. C.

    2014-12-01

    Simulations which integrate both climate physics and the processes by which climate variations are imprinted in and sampled from paleoclimate archives may facilitate differentiation of the climate signal from random and systematic sources of uncertainty. We simulate the former using a newly developed efficient water-isotope-enabled atmospheric GCM, SPEEDY-IER (Molteni, 2003, Dee et al., submitted), and the latter using a toolbox of proxy system models (PSMs, Evans et al., 2013), synthesized, organized and coded within a self-consistent framework (Dee et al., in prep). SPEEDY-IER is forced with SSTs from the Last Millennium PMIP3 integration of the CCSM4 model (Landrum et al., 2012); relevant climate and isotope variables are extracted from the GCM simulation and used to drive PSMs. Through comparing simulated climate fields to simulated observations, we evaluate the extent to which linear and univariate calibrations on local temperature are valid, given bias in the simulated SST, moisture divergence, and associated isotopic composition of water vapor and precipitation. Taking this a step further, PSMs that incorporate the physical, biological, structural, and time-uncertain aspects of each proxy system help to explicitly quantify the errors accompanying the assumption of linear univariate response of proxy systems to climate forcing. We demonstrate the utility of the PSM toolbox with an integrative multi-PSM simulation spanning a realistic pan-tropical pacific proxy network of tree-ring cellulose, speleothem, and ice core oxygen isotopic composition (δ18O). The multi-PSM simulation is used as a testing ground to assess the robustness of frequently invoked teleconnections relating tropical SSTs to terrestrial hydroclimate proxies. By exploring modeled connections between ocean climate and the proxies (both by individual proxy class and for the entire network), we identify which tropical SST signals can be captured by the proxy network, track the individual

  18. Diagnostic boundaries of autism disorder vs pervasive developmental disorder nos comparative observational study and literature review.

    PubMed

    Carigi, Tiziana; Muratori, Filippo; Termine, Cristiano; Veggiotti, Pierangelo; Derhemi, Ledhina; Di Nardo, Roberta; Rossi, Giorgio; Balottin, Umberto

    2014-01-01

    Diagnosis of pervasive developmental disorders (PDDs), and above all diagnosis of the different PDD subtypes, is an ongoing challenge in psychopathology. Application of categorical criteria is complex and problematic in the clinical field where the boundaries dividing some of the PDD entities are blurred, creating particular problems for the clinician. A dimensional clinical approach, considering autistic symptom severity, level of functioning, developmental characteristics and symptoms other than the ones typically observed in autism, may be a more suitable approach in the clinical field and could provide the clinician treating these disorders with empirical guidance. To identify the clinical features that might differentiate the PDD subtypes, we conducted a comparative study in a clinical sample of children affected by autism disorder (AD) or pervasive developmental disorders not otherwise specified (PDD-NOS) and a mini critical review of the available literature addressing clinical and psychopathological differences between the two subtypes. The results of both our study and our literature review seem to show little support for the current PDD subtypes. In such a framework, the most significant element in clinical practice appears to be a deep knowledge of the characteristics of the individual in question. By adopting a broad and multi-faceted perspective, it becomes possible to define the most effective rehabilitation treatment. This applies particularly to the pharmacological treatment, since, to date, no specific therapies for PDDs are known and the choice of pharmacotherapy can be decided only on the basis of the patient's general profile and specific features.

  19. A Field Guide to Extra-Tropical Cyclones: Comparing Models to Observations

    NASA Astrophysics Data System (ADS)

    Bauer, M.

    2008-12-01

    Climate it is said is the accumulation of weather. And weather is not the concern of climate models. Justification for this latter sentiment has long hidden behind coarse model resolutions and blunt validation tools based on climatological maps and the like. The spatial-temporal resolutions of today's models and observations are converging onto meteorological scales however, which means that with the correct tools we can test the largely unproven assumption that climate model weather is correct enough, or at least lacks perverting biases, such that its accumulation does in fact result in a robust climate prediction. Towards this effort we introduce a new tool for extracting detailed cyclone statistics from climate model output. These include the usual cyclone distribution statistics (maps, histograms), but also adaptive cyclone- centric composites. We have also created a complementary dataset, The MAP Climatology of Mid-latitude Storminess (MCMS), which provides a detailed 6 hourly assessment of the areas under the influence of mid- latitude cyclones based on Reanalysis products. Using this we then extract complimentary composites from sources such as ISCCP and GPCP to create a large comparative dataset for climate model validation. A demonstration of the potential usefulness of these tools will be shown. dime.giss.nasa.gov/mcms/mcms.html

  20. Comparative incidence of pregnancy outcomes in treated obstetric antiphospholipid syndrome: the NOH-APS observational study.

    PubMed

    Bouvier, Sylvie; Cochery-Nouvellon, Eva; Lavigne-Lissalde, Géraldine; Mercier, Erick; Marchetti, Tess; Balducchi, Jean-Pierre; Marès, Pierre; Gris, Jean-Christophe

    2014-01-16

    The incidence of pregnancy outcomes for women with the purely obstetric form of antiphospholipid syndrome (APS) treated with prophylactic low-molecular-weight heparin (LMWH) plus low-dose aspirin (LDA) has not been documented. We observed women without a history of thrombosis who had experienced 3 consecutive spontaneous abortions before the 10th week of gestation or 1 fetal loss at or beyond the 10th week. We compared the frequencies of complications during new pregnancies between treated women with APS (n = 513; LMWH + LDA) and women negative for antiphospholipid antibodies as controls (n = 791; no treatment). Among APS women, prior fetal loss was a risk factor for fetal loss, preeclampsia (PE), premature birth, and the occurrence of any placenta-mediated complication. Being positive for anticardiolipin immunoglobulin M antibodies was a risk factor for any placenta-mediated complication. Among women with a history of recurrent abortion, APS women were at a higher risk than other women of PE, placenta-mediated complications, and neonatal mortality. Among women with prior fetal loss, LMWH + LDA-treated APS women had lower pregnancy loss rates but higher PE rates than other women. Improved therapies, in particular better prophylaxis of late pregnancy complications, are urgently needed for obstetric APS and should be evaluated according to the type of pregnancy loss.

  1. The dynamics of human-water systems: comparing observations and simulations

    NASA Astrophysics Data System (ADS)

    Di Baldassarre, G.; Ciullo, A.; Castellarin, A.; Viglione, A.

    2016-12-01

    Real-word data of human-flood interactions are compared to the results of stylized socio-hydrological models. These models build on numerous examples from different parts of the world and consider two main prototypes of floodplain systems. Green systems, whereby societies cope with flood risk via non-structural measures, e.g. resettling out of floodplain areas ("living with floods" approach); and Technological systems, whereby societies cope with flood risk by also via structural measures, e.g. building levees ("fighting floods" approach). The floodplain systems of the Tiber River in Rome and the Ganges-Brahmaputra-Meghna Rivers in Bangladesh systems are used as case studies. The comparison of simulations and observations shows the potential of socio-hydrological models in capturing the dynamics of risk emerging from the interactions and feedbacks between social and hydrological processes, such as learning and forgetting effects. It is then discussed how the proposed approach can contribute to a better understanding of flood risk changes and therefore support the process of disaster risk reduction.

  2. Comparing inversion techniques for constraining CO2 fluxes in the Brazilian Amazon Basin with aircraft observations

    NASA Astrophysics Data System (ADS)

    Chow, V. Y.; Gerbig, C.; Longo, M.; Koch, F.; Nehrkorn, T.; Eluszkiewicz, J.; Ceballos, J. C.; Longo, K.; Wofsy, S. C.

    2012-12-01

    aircraft mixing ratios are applied as a top down constraint in Maximum Likelihood Estimation (MLE) and Bayesian inversion frameworks that solves for parameters controlling the flux. Posterior parameter estimates are used to estimate the carbon budget of the BAB. Preliminary results show that the STILT-VPRM model simulates the net emission of CO2 during both transition periods reasonably well. There is significant enhancement from biomass burning during the November 2008 profiles and some from fossil fuel combustion during the May 2009 flights. ΔCO/ΔCO2 emission ratios are used in combination with continuous observations of CO to remove the CO2 contributions from biomass burning and fossil fuel combustion from the observed CO2 measurements resulting in better agreement of observed and modeled aircraft data. Comparing column calculations for each of the vertical profiles shows our model represents the variability in the diurnal cycle. The high altitude CO2 values from above 3500m are similar to the lateral boundary conditions from CarbonTracker 2010 and GEOS-Chem indicating little influence from surface fluxes at these levels. The MLE inversion provides scaling factors for GEE and R for each of the 8 vegetation types and a Bayesian inversion is being conducted. Our initial inversion results suggest the BAB represents a small net source of CO2 during both of the BARCA intensives.

  3. Three-dimensional simulations of gravitationally confined detonations compared to observations of SN 1991T

    NASA Astrophysics Data System (ADS)

    Seitenzahl, Ivo R.; Kromer, Markus; Ohlmann, Sebastian T.; Ciaraldi-Schoolmann, Franco; Marquardt, Kai; Fink, Michael; Hillebrandt, Wolfgang; Pakmor, Rüdiger; Röpke, Friedrich K.; Ruiter, Ashley J.; Sim, Stuart A.; Taubenberger, Stefan

    2016-07-01

    The gravitationally confined detonation (GCD) model has been proposed as a possible explosion mechanism for Type Ia supernovae in the single-degenerate evolution channel. It starts with ignition of a deflagration in a single off-centre bubble in a near-Chandrasekhar-mass white dwarf. Driven by buoyancy, the deflagration flame rises in a narrow cone towards the surface. For the most part, the main component of the flow of the expanding ashes remains radial, but upon reaching the outer, low-pressure layers of the white dwarf, an additional lateral component develops. This causes the deflagration ashes to converge again at the opposite side, where the compression heats fuel and a detonation may be launched. We first performed five three-dimensional hydrodynamic simulations of the deflagration phase in 1.4 M⊙ carbon/oxygen white dwarfs at intermediate-resolution (2563 computational zones). We confirm that the closer the initial deflagration is ignited to the centre, the slower the buoyant rise and the longer the deflagration ashes takes to break out and close in on the opposite pole to collide. To test the GCD explosion model, we then performed a high-resolution (5123 computational zones) simulation for a model with an ignition spot offset near the upper limit of what is still justifiable, 200 km. This high-resolution simulation met our deliberately optimistic detonation criteria, and we initiated a detonation. The detonation burned through the white dwarf and led to its complete disruption. For this model, we determined detailed nucleosynthetic yields by post-processing 106 tracer particles with a 384 nuclide reaction network, and we present multi-band light curves and time-dependent optical spectra. We find that our synthetic observables show a prominent viewing-angle sensitivity in ultraviolet and blue wavelength bands, which contradicts observed SNe Ia. The strong dependence on the viewing angle is caused by the asymmetric distribution of the deflagration ashes

  4. A highly efficacious pediculicide based on dimeticone: Randomized observer blinded comparative trial

    PubMed Central

    Heukelbach, Jorg; Pilger, Daniel; Oliveira, Fabíola A; Khakban, Adak; Ariza, Liana; Feldmeier, Hermann

    2008-01-01

    Background Infestation with the human head louse (Pediculus humanus capitis) occurs worldwide. Existing treatment options are limited, and reports of resistance to commonly used pediculicides have been increasing. In this trial we assessed the efficacy of a product containing a high (92%) concentration of the silicone oil dimeticone (identical in composition to NYDA®), as compared to a 1% permethrin lotion. Methods Randomized, controlled, observer blinded clinical trial. Participants were recruited from a poor urban neighbourhood in Brazil where pediculosis capitis was highly prevalent. To minimize reinfestation during the trial, participants (145 children aged 5–15 years with head lice infestations) were transferred to a holiday resort outside the endemic area for a period of 9 days. Two applications of dimeticone or 1% permethrin were done, seven days apart. Outcome measures were defined as cure (absence of vital head lice) after first application and before and after second applications, degree of itching, cosmetic acceptability, and clinical pathology. Results Overall cure rates were: day 2 – dimeticone 94.5% (95% CI: 86.6% – 98.5%) and permethrin 66.7% (95% CI: 54.6% – 77.3%; p < 0.0001); day 7 – dimeticone 64.4% (95% CI: 53.3% – 75.3%) and permethrin 59.7% (95% CI: 47.5% – 71.1%; p = 0.5); day 9 – dimeticone 97.2% (95% CI: 90.3% – 99.7%) and permethrin 67.6% (95% CI: 55.4%-78.2%); p < 0.0001). Itching was reduced similarly in both groups. Cosmetic acceptability was significantly better in the dimeticone group as compared to the permethrin group (p = 0.01). Two mild product-related incidents occurred in the dimeticone group. Conclusion The dimeticone product is a safe and highly efficacious pediculicide. Due to its physical mode of action (interruption of the lice's oxygen supply of the central nervous system), development of resistance is unlikely. Trial registration Current Controlled Trials ISRCTN15117709. PMID:18783606

  5. Coagulation Profile Dynamics in Pediatric Patients with Cushing Syndrome: A Prospective, Observational Comparative Study.

    PubMed

    Birdwell, Leah; Lodish, Maya; Tirosh, Amit; Chittiboina, Prashant; Keil, Meg; Lyssikatos, Charlampos; Belyavskaya, Elena; Feelders, Richard A; Stratakis, Constantine A

    2016-10-01

    To evaluate the association between Cushing syndrome and hypercoagulability in children. A prospective, observational study was performed of 54 patients with Cushing syndrome, 15.1 ± 3.9 years, treated at the National Institutes of Health Clinical Center. Coagulation profiles were taken before and 6-12 months after surgery and compared with18 normocortisolemic children, 13.7 ± 3.6 years. At baseline, patients with Cushing syndrome had greater levels of the procoagulant factor VIII (FVIII) vs controls (145 IU/dL ± 84 vs 99 ± 47, P = .04); 6-12 months after surgery, FVIII levels decreased to 111 ± 47, P = .05. Patients with Cushing syndrome had greater levels of the antifibrinolytic α2-antiplasmin, 96 ± 17% vs 82 ± 26%, P = .015. After surgery, antifibrinolytic α2-antiplasmin levels decreased to 82 ± 24%, P < .001. Anticoagulants were greater in patients with Cushing syndrome vs controls at baseline, including protein C (138 ± 41% vs 84 ± 25%, P < .001), protein S (94 ± 19% vs 74 ± 19%, P = .001), and antithrombin III (96 ± 18% vs 77 ± 13%, P < .0001). The 24-hour urinary free cortisol levels correlated positively with FVIII levels, r = 0.43, P = .004. Children with Cushing syndrome had elevated procoagulants, antifibrinolytics, and anticoagulants at baseline compared with controls; normalization of coagulation measures was seen after surgical cure. Despite the increase in anticoagulants, hypercortisolemia is associated with a hypercoagulable state in children, as is the case in adults. This finding has potential implications for prevention of venous thromboembolism in children with Cushing syndrome. ClinicalTrials.gov:NCT00001595. Published by Elsevier Inc.

  6. European Adrenal Insufficiency Registry (EU-AIR): a comparative observational study of glucocorticoid replacement therapy.

    PubMed

    Ekman, Bertil; Fitts, David; Marelli, Claudio; Murray, Robert D; Quinkler, Marcus; Zelissen, Pierre M J

    2014-05-09

    Increased morbidity and mortality associated with conventional glucocorticoid replacement therapy for primary adrenal insufficiency (primary AI; estimated prevalence 93-140/million), secondary AI (estimated prevalence, 150-280/million, respectively) or congenital adrenal hyperplasia (estimated prevalence, approximately 65/million) may be due to the inability of typical glucocorticoid treatment regimens to reproduce the normal circadian profile of plasma cortisol. A once-daily modified-release formulation of hydrocortisone has been developed to provide a plasma cortisol profile that better mimics the daytime endogenous profile of cortisol. Here, we describe the protocol for the European Adrenal Insufficiency Registry (EU-AIR), an observational study to assess the long-term safety of modified-release hydrocortisone compared with conventional glucocorticoid replacement therapies in routine clinical practice (ClinicalTrials.gov identifier: NCT01661387). Patients enrolled in EU-AIR have primary or secondary AI and are receiving either modified-release or conventional glucocorticoid replacement therapy. The primary endpoints of EU-AIR are the incidence of intercurrent illness, adrenal crisis and serious adverse events (SAEs), as well as the duration of SAEs and dose changes related to SAEs. Data relating to morbidity, mortality, adverse drug reactions, dosing and concomitant therapies will be collected. Patient diaries will record illness-related dose changes between visits. All decisions concerning medical care are made by the registry physician and patient. Enrolment is targeted at achieving 3600 patient-years of treatment (1800 patient-years per group) for the primary analysis, which is focused on determining the non-inferiority of once-daily modified-release replacement therapy compared with conventional glucocorticoid therapy. Recruitment began in August 2012 and, as of March 2014, 801 patients have been enrolled. Fifteen centres are participating in Germany, the UK

  7. Determination of dark energy by the Einstein Telescope: Comparing with CMB, BAO, and SNIa observations

    NASA Astrophysics Data System (ADS)

    Zhao, W.; van den Broeck, C.; Baskaran, D.; Li, T. G. F.

    2011-01-01

    A design study is currently in progress for a third-generation gravitational-wave (GW) detector called the Einstein Telescope (ET). An important kind of source for ET will be the inspiral and merger of binary neutron stars up to z˜2. If binary neutron star mergers are the progenitors of short-hard γ-ray bursts, then some fraction of them will be seen both electromagnetically and through GW, so that the luminosity distance and the redshift of the source can be determined separately. An important property of these “standard sirens” is that they are self-calibrating: the luminosity distance can be inferred directly from the GW signal, with no need for a cosmic distance ladder. Thus, standard sirens will provide a powerful independent check of the ΛCDM model. In previous work, estimates were made of how well ET would be able to measure a subset of the cosmological parameters (such as the dark energy parameter w0) it will have access to, assuming that the others had been determined to great accuracy by alternative means. Here we perform a more careful analysis by explicitly using the potential Planck cosmic microwave background data as prior information for these other parameters. We find that ET will be able to constrain w0 and wa with accuracies Δw0=0.099 and Δwa=0.302, respectively. These results are compared with projected accuracies for the JDEM baryon acoustic oscillations project and the SNAP type Ia supernovae observations.

  8. Determination of dark energy by the Einstein Telescope: Comparing with CMB, BAO, and SNIa observations

    SciTech Connect

    Zhao, W.; Baskaran, D.; Van Den Broeck, C.; Li, T. G. F.

    2011-01-15

    A design study is currently in progress for a third-generation gravitational-wave (GW) detector called the Einstein Telescope (ET). An important kind of source for ET will be the inspiral and merger of binary neutron stars up to z{approx}2. If binary neutron star mergers are the progenitors of short-hard {gamma}-ray bursts, then some fraction of them will be seen both electromagnetically and through GW, so that the luminosity distance and the redshift of the source can be determined separately. An important property of these 'standard sirens' is that they are self-calibrating: the luminosity distance can be inferred directly from the GW signal, with no need for a cosmic distance ladder. Thus, standard sirens will provide a powerful independent check of the {Lambda}CDM model. In previous work, estimates were made of how well ET would be able to measure a subset of the cosmological parameters (such as the dark energy parameter w{sub 0}) it will have access to, assuming that the others had been determined to great accuracy by alternative means. Here we perform a more careful analysis by explicitly using the potential Planck cosmic microwave background data as prior information for these other parameters. We find that ET will be able to constrain w{sub 0} and w{sub a} with accuracies {Delta}w{sub 0}=0.099 and {Delta}w{sub a}=0.302, respectively. These results are compared with projected accuracies for the JDEM baryon acoustic oscillations project and the SNAP type Ia supernovae observations.

  9. Filtering and Gridding Satellite Observations of Cloud Variables to Compare with Climate Model Output

    NASA Astrophysics Data System (ADS)

    Pitts, K.; Nasiri, S. L.; Smith, N.

    2013-12-01

    Global climate models have improved considerably over the years, yet clouds still represent a large factor of uncertainty for these models. Comparisons of model-simulated cloud variables with equivalent satellite cloud products are the best way to start diagnosing the differences between model output and observations. Gridded (level 3) cloud products from many different satellites and instruments are required for a full analysis, but these products are created by different science teams using different algorithms and filtering criteria to create similar, but not directly comparable, cloud products. This study makes use of a recently developed uniform space-time gridding algorithm to create a new set of gridded cloud products from each satellite instrument's level 2 data of interest which are each filtered using the same criteria, allowing for a more direct comparison between satellite products. The filtering is done via several variables such as cloud top pressure/height, thermodynamic phase, optical properties, satellite viewing angle, and sun zenith angle. The filtering criteria are determined based on the variable being analyzed and the science question at hand. Each comparison of different variables may require different filtering strategies as no single approach is appropriate for all problems. Beyond inter-satellite data comparison, these new sets of uniformly gridded satellite products can also be used for comparison with model-simulated cloud variables. Of particular interest to this study are the differences in the vertical distributions of ice and liquid water content between the satellite retrievals and model simulations, especially in the mid-troposphere where there are mixed-phase clouds to consider. This presentation will demonstrate the proof of concept through comparisons of cloud water path from Aqua MODIS retrievals and NASA GISS-E2-[R/H] model simulations archived in the CMIP5 data portal.

  10. CFD Simulations of Supersonic Highly Swirling Flow Exiting a Turbine Vane Row Compared with Experimental Observations

    NASA Technical Reports Server (NTRS)

    West, Jeff S.; Richardson, Brian R.; Schmauch, Preston; Kenny, Robert J.

    2011-01-01

    Marshall Space Flight Center (MSFC) has been heavily involved in developing the J2-X engine. The Center has been testing a Work Horse Gas Generator (WHGG) to supply gas products to J2-X turbine components at realistic flight-like operating conditions. Three-dimensional time accurate CFD simulations and analytical fluid analysis have been performed to support WHGG tests at MSFC. The general purpose CFD program LOCI/Chem was utilized to simulate flow of products from the WHGG through a turbine manifold, a stationary row of turbine vanes, into a Can and orifice assembly used to control the back pressure at the turbine vane row and finally through an aspirator plate and flame bucket. Simulations showed that supersonic swirling flow downstream of the turbine imparted a much higher pressure on the Can wall than expected for a non-swirling flow. This result was verified by developing an analytical model that predicts wall pressure due to swirling flow. The CFD simulations predicted that the higher downstream pressure would cause the pressure drop across the nozzle row to be approximately half the value of the test objective. With CFD support, a redesign of the Can orifice and aspirator plate was performed. WHGG experimental results and observations compared well with pre-test and post-test CFD simulations. CFD simulations for both quasi-static and transient test conditions correctly predicted the pressure environment downstream of the turbine row and the behavior of the gas generator product plume as it exited the WHGG test article, impacted the flame bucket and interacted with the external environment.

  11. Russian geomagnetic recordings in 1850-1862 compared to modern observations

    NASA Astrophysics Data System (ADS)

    Viljanen, Ari; Myllys, Minna; Nevanlinna, Heikki

    2014-04-01

    We analyse geomagnetic recordings at four subauroral and midlatitude Russian observatories in 1850-1862. The data consist of spot readings made once in hour of the north and east components of the magnetic field. We use the hourly change of the horizontal field vector as the measure of activity. We compare these values to data from modern observatories at corresponding magnetic latitudes (Nurmijärvi, Finland, magnetic latitude ~57 N; Tartu, Estonia, ~54.5 N; Dourbes, Belgium, ~46 N) by reducing their data to the 1-h format. The largest variations at the Russian observatories occurred during the Carrington storm in September 1859 and they reached about 1000 nT/h, which was the instrumental off-scale limit. When the time stamp for the spot readings happens to be optimal, the top variation in the Nurmijärvi data is about 3700 nT/h (July 1982), and at Tartu the maximum is about 1600 nT/h (November 2004). At a midlatitude site Nertchinsk in Russia (magnetic latitude ~45 N), the variation during the Carrington storm was at the off-scale limit, and exceeded the value observed at Dourbes during the Halloween storm in October 2003. At Nertchinsk, the Carrington event was at least four times larger than any other storm in 1850-1862. Despite the limitations of the old recordings and in using only hourly spot readings, the Carrington storm was definitely a very large event at midlatitudes. At higher latitudes, it remains somewhat unclear whether it exceeds the largest modern storms, especially the one in July 1982.

  12. CT Hounsfield Numbers of Soft Tissues on Unenhanced Abdominal CT Scans: Variability Between Two Different Manufacturers’ MDCT Scanners

    PubMed Central

    Lamba, Ramit; McGahan, John P.; Corwin, Michael T.; Li, Chin-Shang; Tran, Tien; Seibert, J. Anthony; Boone, John M.

    2016-01-01

    OBJECTIVE The purpose of this study is to determine whether Hounsfield numbers of soft tissues on unenhanced abdominal CT of the same patient vary on repeat scans done on two different manufacturers’ MDCT scanners. MATERIALS AND METHODS A database search was performed to identify patients older than 18 years who underwent unenhanced CT of the abdomen and pelvis performed both on a Volume CT (GE Healthcare) and a Definition AS Plus (Siemens Healthcare) 64-MDCT scanner within 12 months of each other. After excluding those patients for whom Hounsfield unit measurements would be affected by mitigating factors, 48 patients (mean age, 58.8 years) were identified. Hounsfield unit measurements were obtained in nine different soft-tissue anatomic locations on each scan, and the location of these sites was kept identical on each scan pair. Data were analyzed to evaluate Hounsfield unit differences between these scanners. RESULTS In general, there was a low consistency in the Hounsfield unit measurements for each of these sites on scans obtained by the two scanners, with the subcutaneous fat in the left posterolateral flank showing the lowest correlation (intraclass correlation coefficient, 0.198). There were differences in the Hounsfield unit measurements obtained in all anatomic sites on scans obtained by both scanners. Mean Hounsfield unit measurements obtained on the Definition AS Plus scanner were lower than those obtained on the Volume CT scanner, with the intriguing exception of the anterior midline subcutaneous fat Hounsfield unit measurements, which were higher on the Definition AS Plus scanner. All differences were statistically significant (p < 0.05). CONCLUSION Hounsfield unit measurements for unenhanced abdominal soft tissues of the same patient vary between scanners of two common MDCT manufacturers. PMID:25341139

  13. CT Hounsfield numbers of soft tissues on unenhanced abdominal CT scans: variability between two different manufacturers' MDCT scanners.

    PubMed

    Lamba, Ramit; McGahan, John P; Corwin, Michael T; Li, Chin-Shang; Tran, Tien; Seibert, J Anthony; Boone, John M

    2014-11-01

    The purpose of this study is to determine whether Hounsfield numbers of soft tissues on unenhanced abdominal CT of the same patient vary on repeat scans done on two different manufacturers' MDCT scanners. A database search was performed to identify patients older than 18 years who underwent unenhanced CT of the abdomen and pelvis performed both on a Volume CT (GE Healthcare) and a Definition AS Plus (Siemens Healthcare) 64-MDCT scanner within 12 months of each other. After excluding those patients for whom Hounsfield unit measurements would be affected by mitigating factors, 48 patients (mean age, 58.8 years) were identified. Hounsfield unit measurements were obtained in nine different soft-tissue anatomic locations on each scan, and the location of these sites was kept identical on each scan pair. Data were analyzed to evaluate Hounsfield unit differences between these scanners. In general, there was a low consistency in the Hounsfield unit measurements for each of these sites on scans obtained by the two scanners, with the subcutaneous fat in the left posterolateral flank showing the lowest correlation (intraclass correlation coefficient, 0.198). There were differences in the Hounsfield unit measurements obtained in all anatomic sites on scans obtained by both scanners. Mean Hounsfield unit measurements obtained on the Definition AS Plus scanner were lower than those obtained on the Volume CT scanner, with the intriguing exception of the anterior midline subcutaneous fat Hounsfield unit measurements, which were higher on the Definition AS Plus scanner. All differences were statistically significant (p < 0.05). Hounsfield unit measurements for unenhanced abdominal soft tissues of the same patient vary between scanners of two common MDCT manufacturers.

  14. Vascular Injuries to the Neck After Penetrating Trauma: Diagnostic Performance of 40- and 64-MDCT Angiography.

    PubMed

    Bodanapally, Uttam K; Dreizin, David; Sliker, Clint W; Boscak, Alexis R; Reddy, Ramachandra P

    2015-10-01

    The purposes of this study were to assess the diagnostic performance of 40- and 64-MDCT angiography with digital subtraction angiography as the reference standard in the detection of arterial injuries in patients at high risk after penetrating neck trauma and to perform a separate analysis of injuries to the external carotid artery. In a retrospective evaluation of 53 sets of angiograms from 51 patients with penetrating neck injury, three reviewers unaware of the digital subtraction angiographic findings reviewed the CT angiographic (CTA) images to discern the presence or absence of arterial injuries. Sensitivity and specificity of CTA were calculated per injury, and a separate analysis of external carotid artery injuries was performed. Sensitivity of CTA for detecting arterial injuries ranged from 75.7% (95% CI, 62.3-86.9%) to 82.2% (95% CI, 69.5-92.1%). Specificity ranged from 96.4% (95% CI, 94.0-98.4%) to 98.4% (95% CI, 96.0-100%). CTA was highly sensitive for detection of the subgroup of injuries involving the large-caliber vessels that contribute to cerebral circulation. These sensitivities ranged from 92.8% (95% CI, 66-98.8%) to 100% (95% CI, 76.6-100%) for internal carotid artery injuries and from 88.9% (95% CI, 65.2-98.3%) to 94.4% (95% CI, 72.6-99.0%) for vertebral artery injuries. In contrast, sensitivity of CTA was limited for external carotid artery injuries, ranging from 63.4% (95% CI, 45.5-79.5%) to 70.0% (95% CI, 52.0-85.0%). CTA can be used for initial evaluation and may help guide management decisions if an external carotid artery injury is detected. Negative findings should not preclude close clinical follow-up, repeat CTA evaluation, or, in the presence of high suspicion of arterial injury due to clinical findings or wound trajectory, evaluation with digital subtraction angiography.

  15. Noninvasive detection of cardiac amyloidosis using delayed enhanced MDCT: a pilot study.

    PubMed

    Deux, Jean-François; Mihalache, Cristian-Ionut; Legou, François; Damy, Thibaud; Mayer, Julie; Rappeneau, Stéphane; Planté-Bordeneuve, Violaine; Luciani, Alain; Kobeiter, Hicham; Rahmouni, Alain

    2015-08-01

    To evaluate myocardial enhancement of patients with cardiac amyloidosis (CA) using computed tomography (CT). Thirteen patients with CA and 11 control patients were examined with first-pass and delayed CT acquisition. A qualitative and quantitative analysis of images was performed. Myocardial attenuation, myocardial signal-to-noise ratio (SNRmyoc), blood pool SNR (SNRblood), contrast-to-noise ratio between blood pool and myocardium (CNRblood-myoc) and relative attenuation index (RAI) defined as variation of myocardial attenuation between delayed and first-pass acquisitions were calculated. Two false negative cases (15 %) and three false positive cases (27 %) were detected on qualitative analysis. SNRmyoc of patients with CA was significantly (p < 0.05) lower on first-pass (4.08 ± 1.9) and higher on delayed acquisition (7.10 ± 2.7) than control patients (6.1 ± 2.2 and 5.03 ± 1.8, respectively). Myocardial attenuation was higher in CA (121 ± 39 HU) than control patients (81 ± 17 HU) on delayed acquisition. CNRblood-myoc was significantly (p < 0.05) lower in CA (1.51 ± 0.7) than control patients (2.85 ± 1.2) on delayed acquisition. The RAI was significantly (p < 0.05) higher in CA (0.12 ± 0.25) than in control patients (-0.56 ± 0.21). Dual phase MDCT can detect abnormal myocardial enhancement in patients with CA. • CT can detect abnormal first-pass and delayed enhancement in cardiac amyloidosis. • Measurement of relative myocardial enhancement between acquisitions helps to detect cardiac amyloidosis. • CT may provide useful data to diagnose cardiac amyloidosis.

  16. Automated diagnosis of interstitial lung diseases and emphysema in MDCT imaging

    NASA Astrophysics Data System (ADS)

    Fetita, Catalin; Chang Chien, Kuang-Che; Brillet, Pierre-Yves; Prêteux, Françoise

    2007-09-01

    Diffuse lung diseases (DLD) include a heterogeneous group of non-neoplasic disease resulting from damage to the lung parenchyma by varying patterns of inflammation. Characterization and quantification of DLD severity using MDCT, mainly in interstitial lung diseases and emphysema, is an important issue in clinical research for the evaluation of new therapies. This paper develops a 3D automated approach for detection and diagnosis of diffuse lung diseases such as fibrosis/honeycombing, ground glass and emphysema. The proposed methodology combines multi-resolution 3D morphological filtering (exploiting the sup-constrained connection cost operator) and graph-based classification for a full characterization of the parenchymal tissue. The morphological filtering performs a multi-level segmentation of the low- and medium-attenuated lung regions as well as their classification with respect to a granularity criterion (multi-resolution analysis). The original intensity range of the CT data volume is thus reduced in the segmented data to a number of levels equal to the resolution depth used (generally ten levels). The specificity of such morphological filtering is to extract tissue patterns locally contrasting with their neighborhood and of size inferior to the resolution depth, while preserving their original shape. A multi-valued hierarchical graph describing the segmentation result is built-up according to the resolution level and the adjacency of the different segmented components. The graph nodes are then enriched with the textural information carried out by their associated components. A graph analysis-reorganization based on the nodes attributes delivers the final classification of the lung parenchyma in normal and ILD/emphysematous regions. It also makes possible to discriminate between different types, or development stages, among the same class of diseases.

  17. A Numerical Study of Heat and Water Vapor Transfer in MDCT-Based Human Airway Models

    PubMed Central

    Wu, Dan; Tawhai, Merryn H.; Hoffman, Eric A.; Lin, Ching-Long

    2014-01-01

    A three-dimensional (3D) thermo-fluid model is developed to study regional distributions of temperature and water vapor in three multi-detector row computed-tomography (MDCT)-basedhuman airwayswith minute ventilations of 6, 15 and 30 L/min. A one-dimensional (1D) model is also solved to provide necessary initial and boundary conditionsforthe 3D model. Both 3D and 1D predicted temperature distributions agree well with available in vivo measurement data. On inspiration, the 3D cold high-speed air stream is split at the bifurcation to form secondary flows, with its cold regions biased toward the inner wall. The cold air flowing along the wall is warmed up more rapidly than the air in the lumen center. The repeated splitting pattern of air streams caused by bifurcations acts as an effective mechanism for rapid heat and mass transfer in 3D. This provides a key difference from the 1D model, where heating relies largely on diffusion in the radial direction, thus significantly affecting gradient-dependent variables, such as energy flux and water loss rate. We then propose the correlations for respective heat and mass transfer in the airways of up to 6 generations: Nu=3.504(ReDaDt)0.277, R = 0.841 and Sh=3.652(ReDaDt)0.268, R = 0.825, where Nu is the Nusselt number, Sh is the Sherwood number, Re is the branch Reynolds number, Da is the airway equivalent diameter, and Dt is the tracheal equivalentdiameter. PMID:25081386

  18. Variation of Jupiter's aurora observed by Hisaki/EXCEED: 1. Observed characteristics of the auroral electron energies compared with observations performed using HST/STIS

    NASA Astrophysics Data System (ADS)

    Tao, Chihiro; Kimura, Tomoki; Badman, Sarah V.; Murakami, Go; Yoshioka, Kazuo; Tsuchiya, Fuminori; André, Nicolas; Yoshikawa, Ichiro; Yamazaki, Atsushi; Shiota, Daikou; Tadokoro, Hiroyasu; Fujimoto, Masaki

    2016-05-01

    Temporal variation of Jupiter's northern aurora is detected using the Extreme Ultraviolet Spectroscope for Exospheric Dynamics (EXCEED) on board JAXA's Earth-orbiting planetary space telescope Hisaki. The wavelength coverage of EXCEED includes the H2 Lyman and Werner bands at 80-148 nm from the entire northern polar region. The prominent periodic modulation of the observed emission corresponds to the rotation of Jupiter's main auroral oval through the aperture, with additional superposed -50%-100% temporal variations. The hydrocarbon color ratio (CR) adopted for the wavelength range of EXCEED is defined as the ratio of the emission intensity in the long wavelength range of 138.5-144.8 nm to that in the short wavelength range of 126.3-130 nm. This CR varies with the planetary rotation phase. Short- (within one planetary rotation) and long-term (> one planetary rotation) enhancements of the auroral power are observed in both wavelength ranges and result in a small CR variation. The occurrence timing of the auroral power enhancement does not clearly depend on the central meridian longitude. Despite the limitations of the wavelength coverage and the large field of view of the observation, the auroral spectra and CR-brightness distribution measured using EXCEED are consistent with other observations.

  19. Synchronous infection of the aorta and the testis: emphysematous epididymo-orchitis, abdominal aortic mycotic aneurysm, and testicular artery pseudoaneurysm diagnosed by use of MDCT.

    PubMed

    Hegde, Rahul G; Balani, Ankit; Merchant, Suleman A; Joshi, Anagha R

    2014-07-01

    We report clinical details and imaging findings for a case of emphysematous epididymo-orchitis with co-existing mycotic abdominal aortic aneurysm and a testicular artery pseudoaneurysm in a diabetic 65-year-old male. We report imaging findings from ultrasonography (USG) and contrast-enhanced multidetector computed tomography (MDCT). Use of MDCT to identify, confirm, and define the extent of the disease, and its utility in understanding the pathogenesis of this rare condition are highlighted. For such lethal infections, early diagnosis and intervention can be lifesaving; imaging can be of crucial importance in this.

  20. Development of density plumes of dissolved CO2: Comparing experimental observations with numerical simulations

    NASA Astrophysics Data System (ADS)

    Kirk, Karen; Vosper, Hayley; Rochelle, Chris; Noy, Dave; Chadwick, Andy

    2014-05-01

    The long-term trapping of CO2 within deep geological storage reservoirs will be dependent upon CO2-water-rock geochemical reactions. The first, and most important, steps in this process will be dissolution of CO2 into the reservoir porewater and the transport of this dissolved CO2 through the reservoir. As part of the CO2CARE project we have investigated these via laboratory tests using a water-filled porous medium. Key experimental parameters were measured to determine system permeability, so that a high-resolution numerical model could be built in an attempt to reproduce the observed system behaviour. The Hele-Shaw cell comprised two glass sheets 65 cm wide and 36 cm high, separated by a spacing of 1.1 mm, and filled with closely-packed glass beads 0.4-0.6 mm in diameter. The surface of the glass was treated to prevent the formation of a higher permeability zone along this interface. A pH-sensitive dye was added to the pore-filling water to show where it had been acidified due to the presence of CO2. CO2 gas was introduced to a space at the top of the cell, which created a thin, diffusion-controlled boundary layer of CO2-rich water below the CO2-water interface. CO2 dissolution increased water density, resulting in gravitational instabilities and the formation of many small, downward-migrating plumes. Time-lapse photography was used to track the formation and progress of these plumes. As the plumes grew they increased in length relative to their width, and decreased in number over time. They also became more complex with time, splitting and forming several lobes, whose outer edges became more diffuse as they mixed with the CO2-poor water. The onset time of plume development and the horizontal wavelength (spacing) of the descending plumes are diagnostic measures of the system properties, notably permeability. They were analysed from the time-lapse images and expressed as probability density functions based on histograms of the observations. The derived

  1. Observation

    ERIC Educational Resources Information Center

    Helfrich, Shannon

    2016-01-01

    Helfrich addresses two perspectives from which to think about observation in the classroom: that of the teacher observing her classroom, her group, and its needs, and that of the outside observer coming into the classroom. Offering advice from her own experience, she encourages and defends both. Do not be afraid of the disruption of outside…

  2. Observations

    ERIC Educational Resources Information Center

    Joosten, Albert Max

    2016-01-01

    Joosten begins his article by telling us that love and knowledge together are the foundation for our work with children. This combination is at the heart of our observation. With this as the foundation, he goes on to offer practical advice to aid our practice of observation. He offers a "List of Objects of Observation" to help guide our…

  3. Night Airglow Observations from Orbiting Spacecraft Compared with Measurements from Rockets.

    PubMed

    Koomen, M J; Gulledge, I S; Packer, D M; Tousey, R

    1963-06-07

    A luminous band around the night-time horizon, observed from orbiting capsules by J. H. Glenn and M. S. Carpenter, and identified as the horizon enhancement of the night airglow, is detected regularly in rocket-borne studies of night airglow. Values of luminance and dip angle of this band derived from Carpenter's observations agree remarkably well with values obtained from rocket data. The rocket results, however, do not support Carpenter's observation that the emission which he saw was largely the atomic oxygen line at 5577 A, but assign the principal luminosity to the green continuum.

  4. Comparative analysis of decametre "drift pair" bursts observed in 2002 and 2015

    NASA Astrophysics Data System (ADS)

    Volvach, Ya. S.; Stanislavsky, A. A.; Konovalenko, A. A.; Koval, A. A.; Dorovskyy, V. V.

    2016-09-01

    We report about new observations of solar "drift pair" (DP) bursts by means of the UTR-2 radio telescope at frequencies 10-30 MHz. Our experimental data include both "forward" and "reverse" bursts with high frequency and time resolution. The records of 301 bursts, observed in 10-12 July of 2015, are investigated. The main properties of these bursts (frequency bandwidth, central frequency and others) have been analysed. In this report our main attention is paid to the comparison of our observations with the similar observations of decametre DPs performed earlier during 13-15 July of 2002 in the same frequency range. Common features of DPs in the two different pieces of data samples have been found. This may indicate the possible presence of stability in the frequency-time properties of decametre DPs from one cycle of solar activity to another.

  5. Comparative study of aerosols observed by YAG lidar and airborne detectors

    NASA Technical Reports Server (NTRS)

    Hirono, M.; Fujiwara, M.; Shibata, T.

    1985-01-01

    The causal relationships of very large (tropical) volcanic eruptions and El Nino Southern Oscillations (ENSO) based on the unequal atmospheric heating by aerosols observed by lidar and airborne detectors are discussed.

  6. Comparative study of aerosols observed by YAG lidar and airborne detectors

    NASA Technical Reports Server (NTRS)

    Hirono, M.; Fujiwara, M.; Shibata, T.

    1985-01-01

    The causal relationships of very large (tropical) volcanic eruptions and El Nino Southern Oscillations (ENSO) based on the unequal atmospheric heating by aerosols observed by lidar and airborne detectors are discussed.

  7. Validity of the modified RULA for computer workers and reliability of one observation compared to six.

    PubMed

    Levanon, Yafa; Lerman, Yehuda; Gefen, Amit; Ratzon, Navah Z

    2014-01-01

    Awkward body posture while typing is associated with musculoskeletal disorders (MSDs). Valid rapid assessment of computer workers' body posture is essential for the prevention of MSD among this large population. This study aimed to examine the validity of the modified rapid upper limb assessment (mRULA) which adjusted the rapid upper limb assessment (RULA) for computer workers. Moreover, this study examines whether one observation during a working day is sufficient or more observations are needed. A total of 29 right-handed computer workers were recruited. RULA and mRULA were conducted. The observations were then repeated six times at one-hour intervals. A significant moderate correlation (r = 0.6 and r = 0.7 for mouse and keyboard, respectively) was found between the assessments. No significant differences were found between one observation and six observations per working day. The mRULA was found to be valid for the assessment of computer workers, and one observation was sufficient to assess the work-related risk factor.

  8. Using data assimilation to compare models of Mars and Venus atmospheres with observations

    NASA Astrophysics Data System (ADS)

    Navarro, Thomas; Forget, Francois; Millour, Ehouarn

    2016-10-01

    Data assimilation is a technique that optimally reconstructs a best estimate of the atmospheric state by combining observations and an a priori provided by a numerical model. The aim of data assimilation is to extrapolate in space and time observations of the atmosphere with the means of a model in order to recover the state of the atmosphere as completely and as accurately as possible.In this work, we employ a state-of-the-art Martian Global Climate Model to assimilate vertical profiles of atmospheric temperature, airborne dust, and water ice clouds retrieved from observations of the Mars Climate Sounder onboard the Mars Reconnaissance Orbiter. The assimilation is carried out using an Ensemble Kalman Filter technique, that maps covariances between model variables. Therefore, observations of one variable (e.g. temperature) can be used to estimate other unobserved variables (e.g. winds), using covariances constructed from an ensemble of model simulations for which initial states slightly differ. Using this method, one can estimate dust from temperature observations only, confirming the presence of detached layers of dust in the atmosphere from their thermal signature. Then, the joint assimilation of temperature, dust, and water ice clouds shows that the performance of the assimilation is limited due to model biases, such as an incorrect phasing of the thermal tide and observed dust diurnal variations unexplained by a model. However, dust estimation makes possible the predictability of the atmosphere, up to around ten days in the most favorable cases, a great improvement over previous studies.Future developments for an improved assimilation strongly suggest to assimilate model parameters, such as the ones for the representation of parameterized atmospheric gravity waves.Also, in the light of the recent global observations of the Venusian atmosphere from the Akastuki spacecraft, the case for the first-ever assimilation of Venus will be made.

  9. Interprofessional primary care team meetings: a qualitative approach comparing observations with personal opinions

    PubMed Central

    van Dongen, Jerôme Jean Jacques; van Bokhoven, Marloes Amantia; Daniëls, Ramon; Lenzen, Stephanie Anna; van der Weijden, Trudy; Beurskens, Anna

    2017-01-01

    Background. The number of people with multiple chronic conditions requiring primary care services increases. Professionals from different disciplines collaborate and coordinate care to deal with the complex health care needs. There is lack of information on current practices regarding interprofessional team (IPT) meetings. Objectives. This study aimed to improve our understanding of the process of interprofessional collaboration in primary care team meetings in the Netherlands by observing the current practice and exploring personal opinions. Methods. Qualitative study involving observations of team meetings and interviews with participants. Eight different IPT meetings (n = 8) in different primary care practices were observed by means of video recordings. Experiences were explored by conducting individual semi-structured interviews (n = 60) with participants (i.e. health care professionals from different disciplines) of the observed team meetings. The data were analysed by means of content analysis. Results. Most participants expressed favourable opinions about their team meetings. However, observations showed that team meetings were more or less hectic, and lacked a clear structure and team coordinator or leader. There appears to be a discrepancy between findings from observations and interviews. From the interviews, four main themes were extracted: (1) Team structure and composition, (2) Patient-centredness, (3) Interaction and (4) Attitude and motivation. Conclusion. IPT meetings could benefit from improvements in structure, patient-centredness and leadership by the chairpersons. Given the discrepancy between observations and interviews, it would appear useful to improve team members’ awareness of aspects that could be improved before training them in dealing with specific challenges. PMID:28122925

  10. Interprofessional primary care team meetings: a qualitative approach comparing observations with personal opinions.

    PubMed

    van Dongen, Jerôme Jean Jacques; van Bokhoven, Marloes Amantia; Daniëls, Ramon; Lenzen, Stephanie Anna; van der Weijden, Trudy; Beurskens, Anna

    2017-02-01

    The number of people with multiple chronic conditions requiring primary care services increases. Professionals from different disciplines collaborate and coordinate care to deal with the complex health care needs. There is lack of information on current practices regarding interprofessional team (IPT) meetings. This study aimed to improve our understanding of the process of interprofessional collaboration in primary care team meetings in the Netherlands by observing the current practice and exploring personal opinions. Qualitative study involving observations of team meetings and interviews with participants. Eight different IPT meetings (n = 8) in different primary care practices were observed by means of video recordings. Experiences were explored by conducting individual semi-structured interviews (n = 60) with participants (i.e. health care professionals from different disciplines) of the observed team meetings. The data were analysed by means of content analysis. Most participants expressed favourable opinions about their team meetings. However, observations showed that team meetings were more or less hectic, and lacked a clear structure and team coordinator or leader. There appears to be a discrepancy between findings from observations and interviews. From the interviews, four main themes were extracted: (1) Team structure and composition, (2) Patient-centredness, (3) Interaction and (4) Attitude and motivation. IPT meetings could benefit from improvements in structure, patient-centredness and leadership by the chairpersons. Given the discrepancy between observations and interviews, it would appear useful to improve team members' awareness of aspects that could be improved before training them in dealing with specific challenges. © The Author 2016. Published by Oxford University Press.

  11. The impacts of open-mouth breathing on upper airway space in obstructive sleep apnea: 3-D MDCT analysis.

    PubMed

    Kim, Eun Joong; Choi, Ji Ho; Kim, Kang Woo; Kim, Tae Hoon; Lee, Sang Hag; Lee, Heung Man; Shin, Chol; Lee, Ki Yeol; Lee, Seung Hoon

    2011-04-01

    Open-mouth breathing during sleep is a risk factor for obstructive sleep apnea (OSA) and is associated with increased disease severity and upper airway collapsibility. The aim of this study was to investigate the effect of open-mouth breathing on the upper airway space in patients with OSA using three-dimensional multi-detector computed tomography (3-D MDCT). The study design included a case-control study with planned data collection. The study was performed at a tertiary medical center. 3-D MDCT analysis was conducted on 52 patients with OSA under two experimental conditions: mouth closed and mouth open. Under these conditions, we measured the minimal cross-sectional area of the retropalatal and retroglossal regions (mXSA-RP, mXSA-RG), as well as the upper airway length (UAL), defined as the vertical dimension from hard palate to hyoid. We also computed the volume of the upper airway space by 3-D reconstruction of both conditions. When the mouth was open, mXSA-RP and mXSA-RG significantly decreased and the UAL significantly increased, irrespective of the severity of OSA. However, between the closed- and open-mouth states, there was no significant change in upper airway volume at any severity of OSA. Results suggest that the more elongated and narrow upper airway during open-mouth breathing may aggravate the collapsibility of the upper airway and, thus, negatively affect OSA severity.

  12. MDCT Anatomic Assessment of Right Inferior Phrenic Artery Origin Related to Potential Supply to Hepatocellular Carcinoma and its Embolization

    SciTech Connect

    Basile, Antonio Tsetis, Dimitrios; Montineri, Arturo; Puleo, Stefano; Massa Saluzzo, Cesare; Runza, Giuseppe; Coppolino, Francesco; Ettorre, Giovanni Carlo; Patti, Maria Teresa

    2008-03-15

    Purpose. To prospectively assess the anatomic variation of the right inferior phrenic artery (RIPA) origin with multidetector computed tomography (MDCT) scans in relation to the technical and angiographic findings during transcatheter arterial embolization of hepatocellular carcinoma (HCC). Methods. Two hundred patients with hepatocellular carcinomas were examined with 16-section CT during the arterial phase. The anatomy of the inferior phrenic arteries was recorded, with particular reference to their origin. All patients with subcapsular HCC located at segments VII and VIII underwent arteriography of the RIPA with subsequent embolization if neoplastic supply was detected. Results. The RIPA origin was detected in all cases (sensitivity 100%), while the left inferior phrenic artery origin was detected in 187 cases (sensitivity 93.5%). RIPAs originated from the aorta (49%), celiac trunk (41%), right renal artery (5.5%), left gastric artery (4%), and proper hepatic artery (0.5%), with 13 types of combinations with the left IPA. Twenty-nine patients showed subcapsular HCCs in segments VII and VIII and all but one underwent RIPA selective angiography, followed by embolization in 7 cases. Conclusion. MDCT assesses well the anatomy of RIPAs, which is fundamental for planning subsequent cannulation and embolization of extrahepatic RIPA supply to HCC.

  13. Medial pathway patterns of the right retromesenteric plane: anatomical investigation using MDCT in patients with acute pancreatitis and pyelonephritis.

    PubMed

    Takaji, Ryo; Mori, Hiromu; Yamada, Yasunari; Kiyonaga, Maki; Matsumoto, Shunro

    2016-01-01

    To investigate the medial pathways of the right retromesenteric plane by reviewing multidetector CT (MDCT) findings in patients with acute pancreatitis and pyelonephritis. 112 patients with acute pancreatitis and 114 patients with pyelonephritis underwent MDCT scans. 64 of the 112 patients with acute pancreatitis and 34 of the 114 patients with pyelonephritis had right retromesenteric plane thickening because of inflammatory extensions. The medial pathways of the right retromesenteric plane were evaluated by two radiologists in consensus. In 18 (28%) of the 64 patients with acute pancreatitis and 10 (29%) of the 34 patients with pyelonephritis, the right retromesenteric plane continued to the central retroperitoneum behind the descending duodenum and pancreatic head (Type 1 pathway). The right retromesenteric plane extended to the right wall of the descending duodenum (Type 2 pathway) in 46 patients (72%) with acute pancreatitis and 24 patients (71%) with pyelonephritis. There was no significant difference in the pathway patterns of the right retromesenteric plane between the acute pancreatitis group and the pyelonephritis group (Type 1 pathway, p = 0.89; Type 2 pathway, p = 0.76). Two patterns were confirmed regarding the medial pathways of the right retromesenteric plane; this anatomical knowledge is important for evaluating the extension of retroperitoneal diseases. Medial aspect of the right retromesenteric plane is thought to have two pathways. The right retromesenteric plane continuing to the right duodenal wall is a common type. Knowledge of these variations is important when evaluating the retroperitoneal diseases.

  14. Medial pathway patterns of the right retromesenteric plane: anatomical investigation using MDCT in patients with acute pancreatitis and pyelonephritis

    PubMed Central

    Mori, Hiromu; Yamada, Yasunari; Kiyonaga, Maki; Matsumoto, Shunro

    2016-01-01

    Objective: To investigate the medial pathways of the right retromesenteric plane by reviewing multidetector CT (MDCT) findings in patients with acute pancreatitis and pyelonephritis. Methods: 112 patients with acute pancreatitis and 114 patients with pyelonephritis underwent MDCT scans. 64 of the 112 patients with acute pancreatitis and 34 of the 114 patients with pyelonephritis had right retromesenteric plane thickening because of inflammatory extensions. The medial pathways of the right retromesenteric plane were evaluated by two radiologists in consensus. Results: In 18 (28%) of the 64 patients with acute pancreatitis and 10 (29%) of the 34 patients with pyelonephritis, the right retromesenteric plane continued to the central retroperitoneum behind the descending duodenum and pancreatic head (Type 1 pathway). The right retromesenteric plane extended to the right wall of the descending duodenum (Type 2 pathway) in 46 patients (72%) with acute pancreatitis and 24 patients (71%) with pyelonephritis. There was no significant difference in the pathway patterns of the right retromesenteric plane between the acute pancreatitis group and the pyelonephritis group (Type 1 pathway, p = 0.89; Type 2 pathway, p = 0.76). Conclusion: Two patterns were confirmed regarding the medial pathways of the right retromesenteric plane; this anatomical knowledge is important for evaluating the extension of retroperitoneal diseases. Advances in knowledge: Medial aspect of the right retromesenteric plane is thought to have two pathways. The right retromesenteric plane continuing to the right duodenal wall is a common type. Knowledge of these variations is important when evaluating the retroperitoneal diseases. PMID:26694254

  15. Quantifying the Hawthorne Effect in Hand Hygiene Compliance Through Comparing Direct Observation With Automated Hand Hygiene Monitoring.

    PubMed

    Hagel, Stefan; Reischke, Jana; Kesselmeier, Miriam; Winning, Johannes; Gastmeier, Petra; Brunkhorst, Frank M; Scherag, André; Pletz, Mathias W

    2015-08-01

    To quantify the Hawthorne effect of hand hygiene performance among healthcare workers using direct observation. Prospective observational study. Intensive care unit, university hospital. Direct observation of hand hygiene compliance over 48 audits of 2 hours each. Simultaneously, hand hygiene events (HHEs) were recorded using electronic alcohol-based handrub dispensers. Directly observed and electronically recorded HHEs during the 2 hours of direct observation were compared using Spearman correlations and Bland-Altman plots. To quantify the Hawthorne effect, we compared the number of electronically recorded HHEs during the direct observation periods with the re-scaled electronically recorded HHEs in the 6 remaining hours of the 8-hour working shift. A total of 3,978 opportunities for hand hygiene were observed during the 96 hours of direct observation. Hand hygiene compliance was 51% (95% CI, 49%-53%). There was a strong positive correlation between directly observed compliance and electronically recorded HHEs (ρ=0.68 [95% CI, 0.49-0.81], P<.0001). In the 384 hours under surveillance, 4,180 HHEs were recorded by the electronic dispensers. Of those, 2,029 HHEs were recorded during the 96 hours in which direct observation was also performed, and 2,151 HHEs were performed in the remaining 288 hours of the same working shift that were not under direct observation. Healthcare workers performed 8 HHEs per hour when not under observation compared with 21 HHEs per hour during observation. Directly and electronically observed HHEs were in agreement. We observed a marked influence of the Hawthorne effect on hand hygiene performance.

  16. Comparative studies on polar ionosphere and magnetotail dynamics based on simultaneous multi-point observations

    NASA Astrophysics Data System (ADS)

    Fukuda, Yoko; Hirahara, Masafumi; Sakanoi, Takeshi; Ebihara, Yusuke; Asamura, Kazushi; Yamazaki, Atsushi; Seki, Kanako; Miyashita, Yukinaga

    For observations of the nightside polar ionosphere, the Reimei satellite is capable of simultane-ous observations for auroral 2D distribution by Multi-spectral Aurora Imaging Camera (MAC) and auroral particles by Electron/Ion Energy Spectrum Analyzer (ESA/ISA). Reimei has been observing the auroral fine structures at altitudes of about 640km by the unprecedented high spatial and temporal resolutions and promoting the understanding of the their fine structures. On the other hand, the field-aligned electric field and Alfven waves have been investigated in the auroral acceleration region by using data of FAST, Polar, Akebono and the other satel-lites. The phenomena in this region are thought to be due to the fluctuation of plasma and electromagnetic field in the magnetotail. In addition to the auroral observations of the polar ionosphere, the data comparison between in the magnetotail and in the polar ionosphere will give us more comprehensive understandings of the auroral phenomena. For observations of the magnetotail, we use data by THEMIS satellites consisting of 5 probes. The simultaneous multipoint observations by these satellites are useful for the distinction between temporal vari-ation and spatial distribution. THEMIS-GBOs(Ground-based observatories) which are located on the Northern America also enable us to observe global aurora. In this presentation, in the dataset for 1.5-years interval possibly providing the simultaneous observations by Reimei and THEMIS, we focus on the data obtained on Feb. 9, 2008. When Reimei passed over Canada(70ILAT) from poleward to equatorward, the Inverted-V precipitating electrons signa-tures lasted about 13 seconds corresponding to 0.7 ILAT width, and the characteristic electron energy was 1-5keV according to the ESA measurement. Near the poleward edge observed for three seconds, a south-eastward flow and a folded arc were observed and then stable and faint aurora was observed according to the MAC. These two types of auroras

  17. Ionospheric simulation compared with Dynamics Explorer observations for November 22, 1981

    NASA Technical Reports Server (NTRS)

    Sojka, J. J.; Bowline, M.; Schunk, R. W.; Craven, J. D.; Frank, L. A.; Sharber, J. R.; Winningham, J. D.; Brace, L. H.

    1992-01-01

    The present study uses an extensive DE-2 data base to both constrain inputs to a time-dependent ionospheric model (TDIM) for a simulation of the ionosphere and then check the simulated densities. The investigation was carried out for both a quiet period and a substorm period. The quiet-day study produced very good agreement between modeled and observed electron densities in the topside ionosphere with two significant exceptions: First, across the polar region the DE-2 LANG densities showed fine structure in addition to the overall regional density morphology. Second, a surprising discrepancy arose in the presunrise and midlatitude trough. The TDIM densities were an order of magnitude lower than those observed by DE-2. The substorm study showed remarkably good agreement with the observed densities.

  18. Comparing regional modeling (CHIMERE) and satellite observations of aerosols (PARASOL): Methodology and case study over Mexico

    NASA Astrophysics Data System (ADS)

    Stromatas, Stavros

    2010-05-01

    S. Stromatas (1), S. Turquety (1), H. Chepfer (1), L. Menut (1), B. Bessagnet (2), JC Pere (2), D. Tanré (3) . (1) Laboratoire de Météorologie Dynamique, CNRS/IPSL, École Polytechnique, 91128 Palaiseau Cedex, France, (2) INERIS, Institut National de l'Environnement Industriel et des Risques, Parc technologique ALATA, 60550 Verneuil en Halatte, FRANCE, (3) Laboratoire d'Optique Atmosphérique/CNRS Univ. des Sciences et Tech. de Lille, 59650 - Villeneuve d'Ascq, France. Atmospheric suspended particles (aerosols) have significant radiative and environmental impacts, affecting human health, visibility and climate. Therefore, they are regulated by air quality standards worldwide, and monitored by regional observation networks. Satellite observations vastly improve the horizontal and temporal coverage, providing daily distributions. Aerosols are currently estimated using aerosol optical depth (AOD) retrievals, a quantitative measure of the extinction of solar radiation by aerosol scattering and absorption between the point of observation and the top of the atmosphere. Even though remarkable progresses in aerosol modeling by chemistry-transport models (CTM) and measurement experiments have been made in recent years, there is still a significant divergence between the modeled and observed results. However, AOD retrievals from satellites remains a highly challenging task mostly because it depends on a variety of different parameters such as cloud contamination, surface reflectance contributions and a priori assumptions on aerosol types, each one of them incorporating its own difficulties. Therefore, comparisons between CTM and observations are often difficult to interpret. In this presentation, we will discuss comparisons between regional modeling (CHIMERE CTM) over Mexico and satellite observations obtained by the POLDER instrument embarked on PARASOL micro-satellite. After a comparison of the model AOD with the retrieved L2 AOD, we will present an alternative

  19. Comparing tracking scenarios to LAGEOS and Etalon by simulating realistic SLR observations

    NASA Astrophysics Data System (ADS)

    Andritsch, Florian; Grahsl, Andrea; Dach, Rolf; Jäggi, Adrian

    2017-04-01

    A tool for simulating realistic Satellite Laser Ranging (SLR) observation scenarios was developed. Analyzing the available observations a profile for each station regarding tracking density, maintenance outage, weather condition on one hand and specific noise behavior for the different targets on the other hand was established. Thus, the simulation is able to reproduce the real and generate realistic, synthetic observation scenarios. Single observations can be added or removed as well as the targets exchanged at specific epochs without affecting the remaining observations. The operational International Laser Ranging Service (ILRS) standard solution provides an important contribution to the International Terrestrial Reference Frame (ITRF). It contains station and geocenter coordinates, and Earth rotation parameters (ERPs). Today they are based on observations to the LAGEOS and Etalon satellites only. Apart from a few limited-time tracking campaigns and suggested priorities among the targets provided by the ILRS each station has their own tracking scheduling and the number of available normal points (NPs, binned full-rate data) available for each satellite are varying from station to station. The purpose of this study is to optimize the tracking scenarios on the stations regarding the main parameters of the analysis (station and geocenter coordinates as well as ERPs). Is it helpful to increase the number of NPs to these standard targets (e.g., by tracking less other satellites) or does a reduction of the tracking not harm the solutions (e.g., to generate the opportunity to support also other satellite missions)? Is it beneficial to coordinate the tracking of the stations in one region to focus on one common or better different targets? These and other related questions will be answered by this study.

  20. Bias in Observational Studies of Prevalent Users: Lessons for Comparative Effectiveness Research From a Meta-Analysis of Statins

    PubMed Central

    Danaei, Goodarz; Tavakkoli, Mohammad; Hernán, Miguel A.

    2012-01-01

    Randomized clinical trials (RCTs) are usually the preferred strategy with which to generate evidence of comparative effectiveness, but conducting an RCT is not always feasible. Though observational studies and RCTs often provide comparable estimates, the questioning of observational analyses has recently intensified because of randomized-observational discrepancies regarding the effect of postmenopausal hormone replacement therapy on coronary heart disease. Reanalyses of observational data that excluded prevalent users of hormone replacement therapy led to attenuated discrepancies, which begs the question of whether exclusion of prevalent users should be generally recommended. In the current study, the authors evaluated the effect of excluding prevalent users of statins in a meta-analysis of observational studies of persons with cardiovascular disease. The pooled, multivariate-adjusted mortality hazard ratio for statin use was 0.77 (95% confidence interval (CI): 0.65, 0.91) in 4 studies that compared incident users with nonusers, 0.70 (95% CI: 0.64, 0.78) in 13 studies that compared a combination of prevalent and incident users with nonusers, and 0.54 (95% CI: 0.45, 0.66) in 13 studies that compared prevalent users with nonusers. The corresponding hazard ratio from 18 RCTs was 0.84 (95% CI: 0.77, 0.91). It appears that the greater the proportion of prevalent statin users in observational studies, the larger the discrepancy between observational and randomized estimates. PMID:22223710

  1. Chiropractic Use and Changes in Health among Older Medicare Beneficiaries: A Comparative Effectiveness Observational Study

    PubMed Central

    Weigel, Paula Anne; Hockenberry, Jason; Bentler, Suzanne; Wolinsky, Fredric D.

    2013-01-01

    Objective The purpose of this study was to investigate the effect of chiropractic on five outcomes among Medicare beneficiaries: increased difficulties performing Activities of Daily Living (ADLs), Instrumental ADLs (IADLs), and Lower Body Functions, as well as lower self-rated health and increased depressive symptoms. Methods Among all beneficiaries, we estimated the effect of chiropractic use on changes in health outcomes among those who used chiropractic compared to those who did not, and among beneficiaries with back conditions we estimated the effect of chiropractic use relative to medical care, both over a 2–15 year period. Two analytic approaches were used—one assumed no selection bias, while the other adjusted for potential selection bias using propensity score methods. Results Among all beneficiaries, propensity score analyses indicated that chiropractic use led to comparable outcomes for ADLs, IADLs, and depressive symptoms, although there were increased risks associated with chiropractic for declines in lower body function and self-rated health. Propensity score analyses among beneficiaries with back conditions indicated that chiropractic use led to comparable outcomes for ADLs, IADLs, lower body function, and depressive symptoms, although there was an increased risk associated with chiropractic use for declines in self-rated health. Conclusion The evidence in this study suggests that chiropractic treatment has comparable effects on functional outcomes when compared to medical treatment for all Medicare beneficiaries, but increased risk for declines in self-rated health among beneficiaries with back conditions. PMID:24144425

  2. Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise

    USDA-ARS?s Scientific Manuscript database

    The comparison of observed global mean surface air temperature (GMT) change to the mean change simulated by climate models has received much attention. For a given global warming signal produced by a climate model ensemble, there exists an envelope of GMT values representing the range of possible un...

  3. Comparative Analysis of Oscillations of a Solar Quiet Region Using Multi-Wavelength Observations

    NASA Astrophysics Data System (ADS)

    Kontogiannis, I.; Tsiropoula, G.; Tziotziou, K.

    2010-07-01

    We analyze the temporal behavior of a solar quiet region using a set of multi-wavelength observations obtained during a coordinated campaign. The observations were acquired by the ground-based Dutch Open Telescope (DOT), the Michelson Doppler Imager (MDI) on-board SOHO and the UV filters of the Transition Region and Coronal Explorer (TRACE). A large range of height in the solar atmosphere, from the deep photosphere to the upper chromosphere is covered by these instruments. We investigate the oscillation properties of the intensities and velocities in distinct regions of the quiet Sun, i.e. internetwork, bright points (NBP) defining the network boundaries and dark mottles forming a well-defined rosette, as observed by the different instruments and in the different heights. The variations of the intensities and velocities are studied with wavelet analysis. The aim of our work is to find similarities and/or differences in the oscillatory phenomena observed in the different examined regions, as well as comprehensive information on the interaction of the oscillations and the magnetic field.

  4. Comparing Vignette Instruction and Assessment Tasks to Classroom Observations and Reflections

    ERIC Educational Resources Information Center

    Jeffries, Carolyn; Maeder, Dale W.

    2011-01-01

    The growing body of research on the use of vignettes in teacher education courses suggests that vignette-based instruction and assessment tasks may represent a viable alternative to traditional forms of scaffolded instruction and reflective essays following classroom observations, thereby creating a bridge between college and K-12 classrooms for…

  5. Observation

    ERIC Educational Resources Information Center

    Patell, Hilla

    2016-01-01

    In order to achieve the goal of observation, preparation of the adult, the observer, is necessary. This preparation, says Hilla Patell, requires us to "have an appreciation of the significance of the child's spontaneous activities and a more thorough understanding of the child's needs." She discusses the growth of both the desire to…

  6. Observation

    ERIC Educational Resources Information Center

    Kripalani, Lakshmi A.

    2016-01-01

    The adult who is inexperienced in the art of observation may, even with the best intentions, react to a child's behavior in a way that hinders instead of helping the child's development. Kripalani outlines the need for training and practice in observation in order to "understand the needs of the children and...to understand how to remove…

  7. Comparing Global Atmospheric CO2 Flux and Transport Models with Remote Sensing (and Other) Observations (Invited)

    NASA Astrophysics Data System (ADS)

    Kawa, S. R.; Collatz, G. J.; Pawson, S.; Wennberg, P. O.; Wofsy, S. C.; Andrews, A. E.

    2010-12-01

    We report recent progress derived from comparison of global CO2 flux and transport models with new remote sensing and other sources of CO2 data including those from satellite. The overall objective of this activity is to improve the process models that represent our understanding of the workings of the atmospheric carbon cycle. Model estimates of CO2 surface flux and atmospheric transport processes are required for initial constraints on inverse analyses, to connect atmospheric observations to the location of surface sources and sinks, to provide the basic framework for carbon data assimilation, and ultimately for future projections of carbon-climate interactions. Models can also be used to test consistency within and between CO2 data sets under varying geophysical states. Here we focus on simulated CO2 fluxes from terrestrial vegetation and atmospheric transport mutually constrained by analyzed meteorological fields from the Goddard Modeling and Assimilation Office for the period 2000 through 2009. Use of assimilated meteorological data enables direct model comparison to observations across a wide range of scales of variability. The biospheric fluxes are produced by the CASA model at 1x1 degrees on a monthly mean basis, modulated hourly with analyzed temperature and sunlight. Both physiological and biomass burning fluxes are derived using satellite observations of vegetation, burned area (as in GFED-3), and analyzed meteorology. For the purposes of comparison to CO2 data, fossil fuel and ocean fluxes are also included in the transport simulations. In this presentation we evaluate the model’s ability to simulate CO2 flux and mixing ratio variability in comparison to remote sensing observations from TCCON, GOSAT, and AIRS as well as relevant in situ observations. Examples of the influence of key process representations are shown from both forward and inverse model comparisons. We find that the model can resolve much of the synoptic, seasonal, and interannual

  8. Comparing Global Atmospheric CO2 Flux and Transport Models with Remote Sensing (and Other) Observations

    NASA Technical Reports Server (NTRS)

    Kawa, S. R.; Collatz, G. J.; Pawson, S.; Wennberg, P. O.; Wofsy, S. C.; Andrews, A. E.

    2010-01-01

    We report recent progress derived from comparison of global CO2 flux and transport models with new remote sensing and other sources of CO2 data including those from satellite. The overall objective of this activity is to improve the process models that represent our understanding of the workings of the atmospheric carbon cycle. Model estimates of CO2 surface flux and atmospheric transport processes are required for initial constraints on inverse analyses, to connect atmospheric observations to the location of surface sources and sinks, to provide the basic framework for carbon data assimilation, and ultimately for future projections of carbon-climate interactions. Models can also be used to test consistency within and between CO2 data sets under varying geophysical states. Here we focus on simulated CO2 fluxes from terrestrial vegetation and atmospheric transport mutually constrained by analyzed meteorological fields from the Goddard Modeling and Assimilation Office for the period 2000 through 2009. Use of assimilated meteorological data enables direct model comparison to observations across a wide range of scales of variability. The biospheric fluxes are produced by the CASA model at 1x1 degrees on a monthly mean basis, modulated hourly with analyzed temperature and sunlight. Both physiological and biomass burning fluxes are derived using satellite observations of vegetation, burned area (as in GFED-3), and analyzed meteorology. For the purposes of comparison to CO2 data, fossil fuel and ocean fluxes are also included in the transport simulations. In this presentation we evaluate the model's ability to simulate CO2 flux and mixing ratio variability in comparison to remote sensing observations from TCCON, GOSAT, and AIRS as well as relevant in situ observations. Examples of the influence of key process representations are shown from both forward and inverse model comparisons. We find that the model can resolve much of the synoptic, seasonal, and interannual

  9. Nonlinear image blending for dual-energy MDCT of the abdomen: can image quality be preserved if the contrast medium dose is reduced?

    PubMed

    Mileto, Achille; Ramirez-Giraldo, Juan Carlos; Marin, Daniele; Alfaro-Cordoba, Marcela; Eusemann, Christian D; Scribano, Emanuele; Blandino, Alfredo; Mazziotti, Silvio; Ascenti, Giorgio

    2014-10-01

    The objective of this study was to compare the image quality of a dual-energy nonlinear image blending technique at reduced load of contrast medium with a simulated 120-kVp linear blending technique at a full dose during portal venous phase MDCT of the abdomen. Forty-five patients (25 men, 20 women; mean age, 65.6 ± 9.7 [SD] years; mean body weight, 74.9 ± 12.4 kg) underwent contrast-enhanced single-phase dual-energy CT of the abdomen by a random assignment to one of three different contrast medium (iomeprol 400) dose injection protocols: 1.3, 1.0, or 0.65 mL/kg of body weight. The contrast-to-noise ratio (CNR) and noise at the portal vein, liver, aorta, and kidney were compared among the different datasets using the ANOVA. Three readers qualitatively assessed all datasets in a blinded and independent fashion. Nonlinear blended images at a 25% reduced dose allowed a significant improvement in CNR (p < 0.05 for all comparisons), compared with simulated 120-kVp linear blended images at a full dose. No statistically significant difference existed in CNR and noise between the nonlinear blended images at a 50% reduced dose and the simulated 120-kVp linear blended images at a full dose. Nonlinear blended images at a 50% reduced dose were considered in all cases to have acceptable image quality. The dual-energy nonlinear image blending technique allows reducing the dose of contrast medium up to 50% during portal venous phase imaging of the abdomen while preserving image quality.

  10. Mental imagery of positive and neutral memories: A fMRI study comparing field perspective imagery to observer perspective imagery.

    PubMed

    Grol, Maud; Vingerhoets, Guy; De Raedt, Rudi

    2017-02-01

    Imagery perspective can influence what information is recalled, processing style, and emotionality; however, the understanding of possible mechanisms mediating these observed differences is still limited. We aimed to examine differences between memory recall from a field perspective and observer perspective at the neurobiological level, in order to improve our understanding of what is underlying the observed differences at the behavioral level. We conducted a fMRI study in healthy individuals, comparing imagery perspectives during recall of neutral and positive autobiographical memories. Behavioral results revealed field perspective imagery of positive memories, as compared to observer perspective, to be associated with more positive feelings afterwards. At the neurobiological level, contrasting observer perspective to field perspective imagery was associated with greater activity, or less decrease relative to the control visual search task, in the right precuneus and in the right temporoparietal junction (TPJ). Greater activity in the right TPJ during an observer perspective as compared to field perspective could reflect performing a greater shift of perspective and mental state during observer perspective imagery than field perspective imagery. Differential activity in the precuneus may reflect that during observer perspective imagery individuals are more likely to engage in (self-) evaluative processing and visuospatial processing. Our findings contribute to a growing understanding of how imagery perspective can influence the type of information that is recalled and the intensity of the emotional response. Observer perspective imagery may not automatically reduce emotional intensity but this could depend on how the imagined situation is evaluated in relation to the self-concept.

  11. Observing Political Systems: Political Systems, Unit One. Comparing Political Experiences, Experimental Materials.

    ERIC Educational Resources Information Center

    Gillespie, Judith A.; Patrick, John J.

    This first of three units of "Comparing Political Experiences", a first-semester course, provides 18 activities which introduce 12th-grade students to political system concepts that they will work with in-depth in succeeding units. The activities and readings, divided into seven sections, stress the development of political knowledge,…

  12. Comparing 3D Solar Model Atmospheres with Observations: Hydrogen Lines and Centre-to-limb Variations

    NASA Astrophysics Data System (ADS)

    Pereira, Tiago M. D.; Asplund, Martin; Trampedach, Regner

    Three dimensional hydrodynamical stellar model atmospheres represent a major step forward in stellar spectroscopy. Making use of radiative-hydrodynamical convection simulations that contain no adjustable free parameters, the model atmospheres provide a robust and realistic treatment of convection. These models have been applied to several lines in the Sun and other stars, yielding an excellent agreement with observations (e.g., Asplund et al. (2000) [1]).

  13. June 13, 2013 U.S. East Coast Meteotsunami: Comparing a Numerical Model With Observations

    NASA Astrophysics Data System (ADS)

    Wang, D.; Becker, N. C.; Weinstein, S.; Whitmore, P.; Knight, W.; Kim, Y.; Bouchard, R. H.; Grissom, K.

    2013-12-01

    On June 13, 2013, a tsunami struck the U.S. East Coast and caused several reported injuries. This tsunami occurred after a derecho moved offshore from North America into the Atlantic Ocean. The presence of this storm, the lack of a seismic source, and the fact that tsunami arrival times at tide stations and deep ocean-bottom pressure sensors cannot be attributed to a 'point-source' suggest this tsunami was caused by atmospheric forces, i.e., a meteotsunami. In this study we attempt to reproduce the observed phenomenon using a numerical model with idealized atmospheric pressure forcing resembling the propagation of the observed barometric anomaly. The numerical model was able to capture some observed features of the tsunami at some tide stations, including the time-lag between the time of pressure jump and the time of tsunami arrival. The model also captures the response at a deep ocean-bottom pressure gauge (DART 44402), including the primary wave and the reflected wave. There are two components of the oceanic response to the propagating pressure anomaly, inverted barometer response and dynamic response. We find that the dynamic response over the deep ocean to be much smaller than the inverted barometer response. The time lag between the pressure jump and tsunami arrival at tide stations is due to the dynamic response: waves generated and/or reflected at the shelf-break propagate shoreward and amplify due to the shoaling effect. The evolution of the derecho over the deep ocean (propagation direction and intensity) is not well defined, however, because of the lack of data so the forcing used for this study is somewhat speculative. Better definition of the pressure anomaly through increased observation or high resolution atmospheric models would improve meteotsunami forecast capabilities.

  14. A Model for Lower Hybrid Wave Excitation Compared with Observations by Viking

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Liemohn, M. W.; Krivorutsky, E. N.; Horwitz, J. L.

    1997-01-01

    The mechanism of lower hybrid wave (LHW) excitation due to the O+ relative drift in a plasma subjected to low-frequency waves (LFWs) is used for analysis of Viking satellite data for events in the cusp/cleft region. In some cases, such a mechanism leads to LHW energy densities and ion distribution functions close to those observed, suggesting the proposed mechanism is a plausible candidate to explain certain classes of LHW generation events in space plasmas.

  15. Colorectal liver metastasis after 90Y radioembolization therapy: pilot study of change in MDCT attenuation as a surrogate marker for future FDG PET response.

    PubMed

    Tochetto, Sandra M; Töre, Hüseyin Gürkan; Chalian, Hamid; Yaghmai, Vahid

    2012-05-01

    The purpose of this study was to investigate whether changes in attenuation and size of liver metastatic lesions of colorectal cancer at MDCT 1 month after (90)Y radioembolization treatment are predictive of response at FDG PET 3 months after treatment. Twenty patients with colorectal liver metastasis consecutively treated with (90)Y radioembolization underwent triphasic MDCT of the liver at baseline and 1 and 3 months after treatment and FDG PET at baseline and 3 months after treatment. Percentage change in tumor attenuation at MDCT (volumetric attenuation), tumor size at MDCT (according to Response Evaluation Criteria in Solid Tumors [RECIST] and World health Organization [WHO] criteria), and volume-weighted maximum standardized uptake value at FDG PET were evaluated. The correlation between FDG PET response 3 months after treatment and response according to RECIST, WHO criteria, and attenuation 1 month after treatment was evaluated. Only 13.3% of patients with FDG PET findings of response 3 months after treatment were identified according to RECIST and WHO criteria 1 month after treatment. According to attenuation criteria at 1 month, however, 53.3% of patients with an FDG PET response at 3 months were identified. A strong association was found between FDG PET response at 3 months and response based on attenuation criteria (odds ratio, 12.4; 95% CI, 0.58-265.3; p = 0.05). Early changes in the attenuation of liver metastatic lesions of colon cancer after (90)Y radioembolization treatment may be predictive of future response at FDG PET.

  16. Low-frequency waves at comet 67P/Churyumov-Gerasimenko. Observations compared to numerical simulations

    NASA Astrophysics Data System (ADS)

    Koenders, C.; Perschke, C.; Goetz, C.; Richter, I.; Motschmann, U.; Glassmeier, K. H.

    2016-10-01

    Context. A new type of low-frequency wave was detected by the magnetometer of the Rosetta Plasma Consortium at the comet during the initial months after the arrival of the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko. This large-amplitude, nearly continuous wave activity is observed in the frequency range from 30 mHz to 80 mHz where 40 mHz to 50 mHz is the dominant frequency. This type of low frequency is not closely related to the gyrofrequency of newborn cometary ions, which differs from previous wave activity observed in the interaction region of comets with the solar wind. Aims: This work aims to reveal a global view on the wave activity region using simulations of the comet-solar wind interaction region. Parameters, such as wavelength, propagation direction, and propagation patterns, are within the focus of this study. While the Rosetta observations only provide local information, numerical simulations provide further information on the global wave properties. Methods: Standard hybrid simulations were applied to the comet-solar wind interaction scenario. In the model, the ions were described as particles, which allows us to describe kinetic processes of the ions. The electrons were described as a fluid. Results: The simulations exhibit a threefold wave structure of the interaction region. A Mach cone and a Whistler wing are observed downstream of the comet. The third kind of wave activity found are low-frequency waves at 97 mHz, which corresponds to the waves observed by Richter et al. (2015, Ann. Geophys., 33, 1031). These waves are caused by the initial pick-up of the cometary ions that are perpendicular to the solar wind flow and in the interplanetary magnetic field direction. The associated electric current becomes unstable. The simulations show that wave activity is only detectable in the + E hemisphere and that the Mach cone and whistler wings need to be distinguished from the newly found instability driven wave activity. The movie associated to

  17. Safety and efficacy of hysteroscopic sterilization compared with laparoscopic sterilization: an observational cohort study

    PubMed Central

    Mao, Jialin; Pfeifer, Samantha; Schlegel, Peter

    2015-01-01

    Objective To compare the safety and efficacy of hysteroscopic sterilization with the “Essure” device with laparoscopic sterilization in a large, all-inclusive, state cohort. Design Population based cohort study. Settings Outpatient interventional setting in New York State. Participants Women undergoing interval sterilization procedure, including hysteroscopic sterilization with Essure device and laparoscopic surgery, between 2005 and 2013. Main outcomes measures Safety events within 30 days of procedures; unintended pregnancies and reoperations within one year of procedures. Mixed model accounting for hospital clustering was used to compare 30 day and 1 year outcomes, adjusting for patient characteristics and other confounders. Time to reoperation was evaluated using frailty model for time to event analysis. Results We identified 8048 patients undergoing hysteroscopic sterilization and 44 278 undergoing laparoscopic sterilization between 2005 and 2013 in New York State. There was a significant increase in the use of hysteroscopic procedures during this period, while use of laparoscopic sterilization decreased. Patients undergoing hysteroscopic sterilization were older than those undergoing laparoscopic sterilization and were more likely to have a history of pelvic inflammatory disease (10.3% v 7.2%, P<0.01), major abdominal surgery (9.4% v 7.9%, P<0.01), and cesarean section (23.2% v 15.4%, P<0.01). At one year after surgery, hysteroscopic sterilization was not associated with a higher risk of unintended pregnancy (odds ratio 0.84 (95% CI 0.63 to 1.12)) but was associated with a substantially increased risk of reoperation (odds ratio 10.16 (7.47 to 13.81)) compared with laparoscopic sterilization. Conclusions Patients undergoing hysteroscopic sterilization have a similar risk of unintended pregnancy but a more than 10-fold higher risk of undergoing reoperation compared with patients undergoing laparoscopic sterilization. Benefits and risks of both procedures

  18. What controls the speed of rip currents? Comparing field observations, numerical simulations, and a parameterization

    NASA Astrophysics Data System (ADS)

    Moulton, M.; Elgar, S.; Raubenheimer, B.; Warner, J. C.

    2016-02-01

    Wave breaking on alongshore non-uniform beaches can drive rip currents near bathymetric depressions. Understanding the controls on the speed of these offshore-directed flows is important for improving predictions of beach hazards, the transport of pollutants and larvae, and morphological evolution. To investigate the response of nearshore flows to non-uniform bathymetry, five channels (on average 30-m wide and 2-m deep) were dredged across the surf zone on the Outer Banks of NC at different times using the propellers of a landing craft, and the subsequent evolution of waves, currents, and morphology was observed for a range of incident wave conditions. In addition, flows are simulated with the COAWST modeling system for the observed incident waves and rip channel bathymetry, and for an extended range of wave conditions and rip channel geometries. A parameter for the maximum offshore-directed flow speed in the surf zone is derived using depth-averaged momentum balances and continuity. The most important terms controlling the offshore-directed flow (rip current) speed are the incident wave height and angle, the water depths in the channel and on the sandbar crest or the terrace through which the channel is incised, and the ratio of wave height to water depth at breaking. The parameter accounts for several wave-breaking regimes, and includes the effect of the suppression of cross-shore flows by the inertia of breaking-wave driven alongshore currents. The parameter has skill predicting the observed and simulated offshore-directed flow speed. Supported by ASDR&E, NDSEG, ONR, and NSF.

  19. Nanoflare Properties throughout Active Regions: Comparing SDO/AIA Observations with Modeled Active Region Light Curves

    NASA Astrophysics Data System (ADS)

    Viall, Nicholeen; Klimchuk, J.

    2012-05-01

    Coronal plasma in active regions is typically measured to be at temperatures near 1-3 MK. Is the majority of the coronal plasma in hydrostatic equilibrium, maintained at these temperatures through a form of quasi-steady heating, or is this simply a measure of the average temperature of widely varying, impulsively heated coronal plasma? Addressing this question is complicated by the fact that the corona is optically thin: many thousands of flux tubes which are heated completely independently are contributing to the total emission along a given line of sight. There is a large body of work focused on the heating of isolated features - coronal loops - which are impulsively heated, however it is the diffuse emission between loops which often comprises the majority of active region emission. Therefore in this study we move beyond isolated features and analyze all of the emission in an entire active region from all contributing flux tubes. We investigate light curves systematically using SDO/AIA observations. We also model the active region corona as a line-of-sight integration of many thousands of completely independently heated flux tubes. The emission from these flux tubes may be time dependent, quasi-steady, or a mix of both, depending on the cadence of heat release. We demonstrate that despite the superposition of randomly heated flux tubes, different distributions of nanoflare cadences produce distinct signatures in light curves observed with multi-wavelength and high time cadence data, such as those from SDO/AIA. We conclude that the majority of the active region plasma is not maintained in hydrostatic equilibrium, rather it is undergoing dynamic heating and cooling cycles. The observed emission is consistent with heating through impulsive nanoflares, whose energy is a function of location within the active region. This research was supported by an appointment to the NASA Postdoctoral Program at GSFC/NASA.

  20. Seasonal and diurnal variations in AMPERE observations of the Birkeland currents compared to modeled results

    NASA Astrophysics Data System (ADS)

    Coxon, J. C.; Milan, S. E.; Carter, J. A.; Clausen, L. B. N.; Anderson, B. J.; Korth, H.

    2016-05-01

    We reduce measurements made by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) to give the total Birkeland (field-aligned) current flowing in both hemispheres in monthly and hourly bins. We analyze these totals using 6 years of data (2010-2015) to examine solar zenith angle-driven variations in the total Birkeland current flowing in both hemispheres, simultaneously, for the first time. A diurnal variation is identified in the total Birkeland current flowing, consistent with variations in the solar zenith angle. A seasonal variation is also identified, with more current flowing in the Northern (Southern) Hemisphere during Bartels rotations in northern (southern) summer. For months close to equinox, more current is found to flow in the Northern Hemisphere, contrary to our expectations. We also conduct the first test of the Milan (2013) model for estimating Birkeland current magnitudes, with modifications made to account for solar contributions to ionospheric conductance based on the observed variation of the Birkeland currents with season and time of day. The modified model, using the value of ΦD averaged by Bartels rotation (scaled by 1.7), is found to agree with the observed AMPERE currents, with a correlation of 0.87 in the Northern Hemisphere and 0.86 in the Southern Hemisphere. The improvement over the correlation with dayside reconnection rate is demonstrated to be a significant improvement to the model. The correlation of the residuals is found to be consistent with more current flowing in the Northern Hemisphere. This new observation of systematically larger current flowing in the Northern Hemisphere is discussed in the context of previous results which suggest that the Northern Hemisphere may react more strongly to dayside reconnection than the Southern Hemisphere.

  1. Nanoflare Properties throughout Active Regions: Comparing SDO/AIA Observations with Modeled Active Region Light Curves

    NASA Technical Reports Server (NTRS)

    Viall, Nicholeen

    2012-01-01

    Coronal plasma in active regions is typically measured to be at temperatures near 1-3 MK. Is the majority of the coronal plasma in hydrostatic equilibrium, maintained at these temperatures through a form of quasi-steady heating, or is this simply a measure of the average temperature of widely varying, impulsively heated coronal plasma? Addressing this question is complicated by the fact that the corona is optically thin: many thousands of flux tubes which are heated completely independently are contributing to the total emission along a given line of sight. There is a large body of work focused on the heating of isolated features - coronal loops - which are impulsively heated, however it is the diffuse emission between loops which often comprises the majority of active region emission. Therefore in this study we move beyond isolated features and analyze all of the emission in an entire active region from all contributing flux tubes. We investigate light curves systematically using SDO/AIA observations. We also model the active region corona as a line-of-sight integration of many thousands of completely independently heated flux tubes. The emission from these flux tubes may be time dependent, quasi-steady, or a mix of both, depending on the cadence of heat release. We demonstrate that despite the superposition of randomly heated flux tubes, different distributions of nanoflare cadences produce distinct signatures in light curves observed with multi-wavelength and high time cadence data, such as those from SDO/AIA. We conclude that the majority of the active region plasma is not maintained in hydrostatic equilibrium, rather it is undergoing dynamic heating and cooling cycles. The observed emission is consistent with heating through impulsive nanoflares, whose energy is a function of location within the active region.

  2. Comparing simulated PSC optical properties with CALIPSO observations during the 2010 Antarctic winter

    NASA Astrophysics Data System (ADS)

    Zhu, Yunqian; Toon, Owen B.; Pitts, Michael C.; Lambert, Alyn; Bardeen, Charles; Kinnison, Douglas E.

    2017-01-01

    We simulate polar stratospheric clouds (PSCs) during the Antarctic winter of 2010 using the Specified Dynamics version of the Whole Atmosphere Community Climate Model/Community Aerosol and Radiation Model for Atmospheres (SD-WACCM/CARMA) model. The current PSC model contains microphysical schemes for supercooled ternary solutions (STS) and nitric acid trihydrate (NAT) particles, as well as a prognostic treatment for PSC ice particles and dehydration. Our simulations and CALIPSO satellite data suggest two major NAT particle formation mechanisms. The first mechanism is the nucleation of NAT from STS. Our model, with homogeneous nucleation rates of NAT from STS constrained by observations from the Arctic winter of 2010-2011, reproduces optical properties observed by CALIPSO over Antarctica in May and the timing of denitrification observed by the Microwave Limb Sounder within their uncertainties. On the other hand, the CALIPSO data indicate that our simulations are missing clouds containing small NAT particles with large number densities. We suggest these particles are most likely to form from ice clouds or STS in gravity waves, as found by previous investigations. The simulated cloud coverage agrees with the CALIPSO cloud coverage within a few percent on average with a correlation coefficient of 0.83. However, using the CALIPSO classification algorithm, simulated ice clouds often fall into Mix categories under the denitrified and dehydrated conditions. The model needs an improved ice microphysical representation, not only to allow ice particles to be a source of NAT but also to provide information on ice cloud particle number and size so that ice cloud optical properties can be more precisely calculated for comparison with CALIPSO data.

  3. Accuracy of comparing bone quality to chocolate bars for patient information purposes: observational study.

    PubMed

    Jones, Phil; Jones, Sarah; Stone, Debbie

    2007-12-22

    To test whether standard information for patients using Crunchie and Aero chocolate bars to explain bone health and risk of fracture is robust. Observational study. Domestic kitchen in rural west Wales. 10 Crunchie bars and 10 Aero bars. Fracture after falls from varying heights. Both Crunchie and Aero bars exhibited the same T and Z scores for bone density. Crunchie bars had a lower chocolate mass index than the Aero bars. Crunchie bars are more liable to fracture. Using Crunchie and Aero chocolate bars to explain bone structure to patients may be visually attractive but oversimplifies the situation.

  4. Comparative study of a substorm event by satellite observation and model simulation

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Ma, ShuYing; Ridley, A. J.

    2010-03-01

    A substorm event has been simulated for the first time by using SWMF (Space Weather Modeling Framework) developed by the University of Michigan. The model results have been validated using Geotail and Cluster satellite observations. The substorm onset occurs at 22:08 UT on September 28 2004, as identified from FUV WIC observations on the NASA IMAGE spacecraft. SWMF can couple effectively the magnetosphere, inner magnetosphere and ionosphere processes and is driven by the solar wind and IMF (Interplanetary Magnetic Field) parameters, which are measured by ACE satellite and time delayed to the upstream boundary of the model. It shows that (1) SWMF can predict well the large-scale variations of the magnetospheric magnetic field and ionospheric currents during the substorm event; and (2) the accuracy of the time delay of the solar wind from ACE to the outer boundary of the model has great effects on the model results. Finally, the substorm trigger mechanism has been discussed and the way of improvement of the model has been pointed out.

  5. A comparative analysis of simulated and observed photosynthetic CO2 uptake in two coniferous forest canopies.

    PubMed

    Ibrom, Andreas; Jarvis, Paul G; Clement, Robert; Morgenstern, Kai; Oltchev, Alexander; Medlyn, Belinda E; Wang, Ying Ping; Wingate, Lisa; Moncrieff, John B; Gravenhorst, Gode

    2006-07-01

    Gross canopy photosynthesis (P(g)) can be simulated with canopy models or retrieved from turbulent carbon dioxide (CO2) flux measurements above the forest canopy. We compare the two estimates and illustrate our findings with two case studies. We used the three-dimensional canopy model MAESTRA to simulate P(g) of two spruce forests differing in age and structure. Model parameter acquisition and model sensitivity to selected model parameters are described, and modeled results are compared with independent flux estimates. Despite higher photon fluxes at the site, an older German Norway spruce (Picea abies L. (Karst.)) canopy took up 25% less CO2 from the atmosphere than a young Scottish Sitka spruce (Picea sitchensis (Bong.) Carr.) plantation. The average magnitudes of P(g) and the differences between the two canopies were satisfactorily represented by the model. The main reasons for the different uptake rates were a slightly smaller quantum yield and lower absorptance of the Norway spruce stand because of a more clumped canopy structure. The model did not represent the scatter in the turbulent CO2 flux densities, which was of the same order of magnitude as the non-photosynthetically-active-radiation-induced biophysical variability in the simulated P(g). Analysis of residuals identified only small systematic differences between the modeled flux estimates and turbulent flux measurements at high vapor pressure saturation deficits. The merits and limitations of comparative analysis for quality evaluation of both methods are discussed. From this analysis, we recommend use of both parameter sets and model structure as a basis for future applications and model development.

  6. GEM-CEDAR Challenge: Comparing Ionospheric Models with Poynting Flux from DMSP Observations

    NASA Technical Reports Server (NTRS)

    Rastaetter, Lutz; Kuznetsova, Maria; Shim, Ja-Soon; Hesse, Michael; Knipp, Delores J.; Weimer, Daniel R.; Fuller-Rowell, Timothy J.; Ridley, Aaron J.; Raeder, Joachim; Maruyama, Naomi; Kilcomons, Liam; Wittberger, Michael James

    2011-01-01

    As part to the GEM-CEDAR challenge we are extending the model-data comparisons to electrodynamic in-situ measurements in low-Earth orbit. We use DMSP observations of electric and magnetic fields to compute Poynting Flux values along the satellite track in high latitudes including the auroral zones and the polar cap. Models of the ionosphere that include electrodynamic parameters have been run for five events selected for the GEM-CEDAR modeling challenge for which DMSP data are available for comparison. Combined with a magnetic field model we use the modeled electric fields to compute Poynting Flux and Joule Dissipation values from outputs of CTIPe, TIE-GCM, the ionospheric electrodynamics solvers of the SWMF, LFM and OpenGGCM magnetosphere-ionosphere coupled models, and the Weimer electric field model. The online metrics analysis tool at the Community Coordinated Modeling Center (CCMC) has been updated to handle the analysis of separate short segments of available data (high-latitude sections of the satellite orbit) with model outputs to analyze how well auroral patterns are being reproduced by the models. We present initial results from the new analysis tool in terms of model yields (ratio of the difference between maximum and minimum values of model results to the observation), timing/location errors of local maxima in the inbound and outbound auroral crossings as well as cross-correlations for individual passes. We collect the information for many DMSP passes and present an analysis for model performance during quiet and geomagnetically disturbed time periods using half-orbit integrated values as well.

  7. COMPARATIVE STUDY OF ASYMMETRY ORIGIN OF GALAXIES IN DIFFERENT ENVIRONMENTS. I. OPTICAL OBSERVATIONS

    SciTech Connect

    Plauchu-Frayn, I.; Coziol, R. E-mail: rcoziol@astro.ugto.m

    2010-06-15

    This paper presents the first of two analyses about the influence of environment on the formation and evolution of galaxies observed in the nearby universe. For our study, we used three different samples representing different density environments: galaxies in Compact Groups (HCGs), Isolated Pairs of Galaxies (KPGs), and Isolated Galaxies (KIGs), which were taken as references. Usingboth characteristic isophotal parameters and evidence of asymmetries in the optical and the near-infrared, we are able to establish differences in the characteristics of galaxies with different morphologies in different environments, allowing us to better understand their different formation histories. In this first paper, we present the isophotal and asymmetry analyses of a sample of 214 galaxies in different environments observed in the optical (V and I images). For each galaxy, we have determined different characteristic isophotal parameters and V - I color profiles, as a function of semi-major axis, and performed a full asymmetry analysis in residual images using the V filter. Evidence of asymmetry in the optical is almost missing in the KIG sample and significantly more common in the KPG than in the HCG samples. Our isophotal analysis suggests that the stellar populations in the HCG galaxies are older and more dynamically relaxed than in the KPG. The HCG galaxies seem to be at a more advanced stage of interaction than the KPGs. One possible explanation is that these structures formed at different epochs: compact groups of galaxies would have formed before close pairs of galaxies, which only began interacting recently. However, similarities in the formation process of galaxies with same morphology suggest CGs and close pairs of galaxies share similar conditions; they are new structures forming relatively late in low-density environments.

  8. GEM-CEDAR Challenge: Comparing Ionospheric Models with Poynting Flux from DMSP Observations

    NASA Technical Reports Server (NTRS)

    Rastaetter, Lutz; Kuznetsova, Maria; Shim, Ja-Soon; Hesse, Michael; Knipp, Delores J.; Weimer, Daniel R.; Fuller-Rowell, Timothy J.; Ridley, Aaron J.; Raeder, Joachim; Maruyama, Naomi; hide

    2011-01-01

    As part to the GEM-CEDAR challenge we are extending the model-data comparisons to electrodynamic in-situ measurements in low-Earth orbit. We use DMSP observations of electric and magnetic fields to compute Poynting Flux values along the satellite track in high latitudes including the auroral zones and the polar cap. Models of the ionosphere that include electrodynamic parameters have been run for five events selected for the GEM-CEDAR modeling challenge for which DMSP data are available for comparison. Combined with a magnetic field model we use the modeled electric fields to compute Poynting Flux and Joule Dissipation values from outputs of CTIPe, TIE-GCM, the ionospheric electrodynamics solvers of the SWMF, LFM and OpenGGCM magnetosphere-ionosphere coupled models, and the Weimer electric field model. The online metrics analysis tool at the Community Coordinated Modeling Center (CCMC) has been updated to handle the analysis of separate short segments of available data (high-latitude sections of the satellite orbit) with model outputs to analyze how well auroral patterns are being reproduced by the models. We present initial results from the new analysis tool in terms of model yields (ratio of the difference between maximum and minimum values of model results to the observation), timing/location errors of local maxima in the inbound and outbound auroral crossings as well as cross-correlations for individual passes. We collect the information for many DMSP passes and present an analysis for model performance during quiet and geomagnetically disturbed time periods using half-orbit integrated values as well.

  9. A Comparative Observational Study of YSO Classification in Four Small Star-forming H ii Regions

    NASA Astrophysics Data System (ADS)

    Kang, Sung-Ju; Kerton, C. R.; Choi, Minho; Kang, Miju

    2017-08-01

    We have developed a new young stellar object (YSO) identification and classification technique using mid-infrared Wide-field Infrared Survey Explorer (WISE) data. We compare this new technique with previous WISE YSO detection and classification methods that used either infrared colors or spectral energy distribution slopes. In this study, we also use the new technique to detect and examine the YSO population associated with four small H ii regions: KR 7, KR 81, KR 120, and KR 140. The relatively simple structure of these regions allows us to effectively use both spatial and temporal constraints to identify YSOs that are potential products of triggered star formation. We are also able to identify regions of active star formation around these H ii regions that are clearly not influenced by the H ii region expansion, and thus demonstrate that star formation is on-going on megayear timescales in some of these molecular clouds.

  10. Changes in hospital costs after introducing an intermediate care unit: a comparative observational study

    PubMed Central

    Solberg, Barbara CJ; Dirksen, Carmen D; Nieman, Fred HM; van Merode, Godefridus; Poeze, Martijn; Ramsay, Graham

    2008-01-01

    Introduction The high cost of critical care resources has resulted in strategies to reduce the costs of ruling out low-risk patients by developing intermediate care units (IMCs). The aim of this study was to compare changes in total hospital costs for intensive care patients before and after the introduction of an IMC at the University Hospital Maastricht. Methods The design was a comparative longitudinal study. The setting was a university hospital with a mixed intensive care unit (ICU), an IMC, and general wards. Changes in total hospital costs were measured for patients who were admitted to the ICU before and after the introduction of the IMC. The comparison of interest was the opening of a six-bed mixed IMC. Results The mean total hospital cost per patient increased significantly. Before the introduction of the IMC, the total hospital cost per patient was €12,961 (± €14,530) and afterwards it rose to €16,513 (± €17,718). Multiple regression analysis was used to determine to what extent patient characteristics explained these higher hospital costs using mortality, type of stay, diagnostic categories, length of ICU and ward stay, and the Therapeutic Intervention Scoring System (TISS) as predictors. More surgical patients, greater requirements of therapeutic interventions on the ICU admission day, and longer ICU stay in patients did explain the increase in hospital costs, rather than the introduction of the IMC. Conclusion After the introduction of the IMC, the higher mean total hospital costs for patients with a high TISS score and longer ICU stay explained the cost increase. PMID:18482443

  11. A retrospective observational study comparing hair apposition technique, suturing and stapling for scalp lacerations

    PubMed Central

    2013-01-01

    Aim Scalp lacerations are commonly encountered in patients presenting to emergency department with trauma. Lacerations are repaired with suturing, stapling, adhesive tapes, and tissue adhesives. In this study, we aimed to compare the effectiveness of suturing, stapling, and hair apposition techniques used in repair of scalp lacerations in patients who presented to emergency department with scalp laceration. Materials and method After obtaining approval of local ethics committee, we examined the effects of the three technique used to repair scalp lacerations on wound healing, complication rate, and patient satisfaction by recording data. Categorical variables were expressed as n and %. X2 test was used for statistical analysis. A p value less than 0.05 was accepted statistically significant. Results Our study included a total of 134 patients of whom were treated 37 (27.6%) with hair apposition technique 49, 48 (35.8%) with suturing, and (36.6%) with stapling. There was a significant difference between the scalp repair technique and 7th and 15th day patient satisfaction rates in favor of the hair apposition technique (p < 0.05). There was a significant difference between the scalp repair technique and cosmetic problems after 15 days (p < 0.05). Cosmetic problems 15 days after the procedure were significantly lower in the hair apposition technique. Conclusion In patients presenting to emergency departments with linear scalp laceration suturing, stapling, and hair apposition techniques can be safely applied. However, hair apposition technique has the advantages of being more satisfying, and having lower cosmetic problem and complication rates compared with other techniques. PMID:23885743

  12. Pancreatic ductal adenocarcinoma and chronic mass-forming pancreatitis: Differentiation with dual-energy MDCT in spectral imaging mode.

    PubMed

    Yin, Qihua; Zou, Xinnong; Zai, Xiaodong; Wu, Zhiyuan; Wu, Qingyang; Jiang, Xingyu; Chen, Hongwei; Miao, Fei

    2015-12-01

    To investigate the value of dual-energy MDCT in spectral imaging in the differential diagnosis of chronic mass-forming chronic pancreatitis (CMFP) and pancreatic ductal adenocarcinoma (PDAC) during the arterial phase (AP) and the pancreatic parenchymal phase (PP). Thirty five consecutive patients with CMFP (n=15) or PDAC (n=20) underwent dual-energy MDCT in spectral imaging during AP and PP. Iodine concentrations were derived from iodine-based material-decomposition CT images and normalized to the iodine concentration in the aorta. The difference in iodine concentration between the AP and PP, contrast-to-noise ratio (CNR) and the slope K of the spectrum curve were calculated. Normalized iodine concentrations (NICs) in patients with CMFP differed significantly from those in patients with PDAC during two double phases (mean NIC, 0.26±0.04 mg/mL vs. 0.53±0.02 mg/mL, p=0.0001; 0.07±0.02 mg/mL vs. 0.28±0.04 mg/mL, p=0.0002, respectively). There were significant differences in the value of the slope K of the spectrum curve in two groups during AP and PP (K(CMFP)=3.27±0.70 vs. K(PDAC)=1.35±0.41, P=0.001, and K(CMFP)=3.70±0.17 vs. K(PDAC)=2.16±0.70, p=0.003, respectively). CNRs at low energy levels (40-70 keV) were higher than those at high energy levels (80-40 keV). Individual patient CNR-optimized energy level images and the NIC can be used to improve the sensitivity and the specificity for differentiating CMFP from PDAC by use of dual-energy MDCT in spectral imaging with fast tube voltage switching. Copyright © 2015. Published by Elsevier Ireland Ltd.

  13. Are periprosthetic tissue reactions observed after revision of total disc replacement comparable to the reactions observed after total hip or knee revision surgery?

    PubMed Central

    Punt, Ilona M.; Austen, Shennah; Cleutjens, Jack P.M.; Kurtz, Steven M.; ten Broeke, René H.M.; van Rhijn, Lodewijk W.; Willems, Paul C.; van Ooij, André

    2011-01-01

    Study design Comparative study. Objective To compare periprosthetic tissue reactions observed after total disc replacement (TDR), total hip arthroplasty (THA) and total knee arthroplasty (TKA) revision surgery. Summary of background data Prosthetic wear debris leading to particle disease, followed by osteolysis, is often observed after THA and TKA. Although the presence of polyethylene (PE) particles and periprosthetic inflammation after TDR has been proven recently, osteolysis is rarely observed. The clinical relevance of PE wear debris in the spine remains poorly understood. Methods Number, size and shape of PE particles, as well as quantity and type of inflammatory cells in periprosthetic tissue retrieved during Charité TDR (n=22), THA (n=10) and TKA (n=4) revision surgery were compared. Tissue samples were stained with hematoxylin/eosin and examined by using light microscopy with bright field and polarized light. Results After THA, large numbers of PE particles <6 µm were observed, which were mainly phagocytosed by macrophages. The TKA group had a broad size range with many larger PE particles and more giant cells. In TDR, the size range was similar to that observed in TKA. However, the smallest particles were the most prevalent with 75% of the particles being <6 µm, as seen in revision THA. In TDR, both macrophages and giant cells were present with a higher number of macrophages. Conclusions Both small and large PE particles are present after TDR revision surgery compatible with both THA and TKA wear patterns. The similarities between periprosthetic tissue reactions in the different groups may give more insight in the clinical relevance of PE particles and inflammatory cells in the lumbar spine. The current findings may help to improve TDR design as applied from technologies previously developed in THA and TKA with the goal of a longer survival of TDR. PMID:21336235

  14. A comparative study of local galaxy clusters - I. Derived X-ray observables

    NASA Astrophysics Data System (ADS)

    Rozo, E.; Rykoff, E. S.; Bartlett, J. G.; Evrard, A.

    2014-02-01

    We examine systematic differences in the derived X-ray properties of galaxy clusters as reported by three different groups: Vikhlinin et al., Mantz et al. and Plank Collaboration. The sample overlap between any two pairs of works ranges between 16 to 28 galaxy clusters. We find systematic differences in most reported X-ray properties, including the total cluster mass, M500. The most extreme case is an average 45 ± 5 per cent difference in cluster mass between the Plank Collaboration and Mantz et al., for clusters at z > 0.13 (averaged over 16 clusters). These differences also induce differences in cluster observables defined within an R500 aperture. After accounting for aperture differences, we find very good agreement in gas mass estimates between the different groups. However, the soft-band X-ray luminosity, LX, core-excised spectroscopic temperature, TX, and gas thermal energy, YX = MgasTX display mean differences at the 5-15 per cent level. We also find that the low (z ≤ 0.13) and high (z ≥ 0.13) redshift galaxy cluster samples in Plank Collaboration appear to be systematically different: the YSZ/YX ratio for each of these two sub-samples is ln (YSZ/YX) = -0.06 ± 0.04 and ln (YSZ/YX) = 0.08 ± 0.04, respectively.

  15. Posthole Broadband Sensor Emplacement vs. Surface Vaults: Observations of Comparative Noise Performance and Trade-offs

    NASA Astrophysics Data System (ADS)

    Sweet, J. R.; Beaudoin, B. C.; Barstow, N.; Pfeifer, M.; Anderson, K. R.; Frassetto, A.

    2015-12-01

    Advances in seismometer design have diversified the range of instruments available for use in temporary field installations. IRIS programs, primarily PASSCAL and the Transportable Array (TA), have helped steer development of these new instruments to meet these evolving needs. PASSCAL operates a small pool of posthole broadband sensors, purpose built for direct burial. Near surface posthole installations are a new, cost effective, and logistically simple technique for broadband emplacement that is an alternative to the vault installations used in portable broadband seismic experiments for nearly 30 years. Direct burial installation is limited to the time and effort required to dig the borehole and emplace the sensor, thus reducing both material costs and time to install. Also, in Alaska, extreme environments and difficult logistics make standard TA tank vaults inappropriate for most sites. TA has developed improved deployment strategies for these environments. There, holes for posthole sensors are hammer- drilled or augered to several meters depth in soil, permafrost, or bedrock and then cased. These emplacement costs are generally less than standard TA vaults. We compare various installation techniques for test cases as well as general deployments of PASSCAL and TA stations. Automated noise performance analyses have been part of the TA throughout its operation, but until recently vault performance for portable installations supported by the PASSCAL program was sparse. In this study, we select a suite of co-located direct burial and surface vault installations and compare their noise performance using probability density functions. Our initial analyses suggest that direct burial sensors have lower noise levels than vault installations on both horizontal and vertical channels across a range of periods spanning <1 s to 100 s. However, most of these initial experiments for PASSCAL were with sensors not purpose built for direct burial and it became obvious that a sensor

  16. Comparing ECMWF AOD with AERONET observations at visible and UV wavelengths

    NASA Astrophysics Data System (ADS)

    Cesnulyte, V.; Lindfors, A. V.; Pitkänen, M. R. A.; Lehtinen, K. E. J.; Morcrette, J.-J.; Arola, A.

    2014-01-01

    This paper presents validation results of the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System MACC (Monitoring Atmospheric Composition and Climate) re-analysis aerosol optical depth (AOD) for the period 2003-2006. We evaluate the MACC AOD at a UV wavelength (340 nm) and at mid-visible (500 and 550 nm) by comparing against ground-based AERONET measurements at 12 sites. The AERONET sites cover various parts of the globe and are categorized in three groups: urban/anthropogenic, biomass burning and dust, depending on the typically dominating aerosol type. This is the first time a global model such as the ECMWF has been evaluated for the performance of AOD at a UV wavelength. The results show that the MACC system generally provides a good representation of the AOD on a monthly basis, showing a realistic seasonal cycle. The model is mostly able to capture major dust load events and also the peak months of biomass burning correctly. For Kanpur and Solar Village, however, the model overestimates the AOD during the monsoon period when the aerosol load is generally low. When comparing hourly AOD values, the model-measurement agreement is better for biomass burning and dust sites than for urban sites, with an average correlation coefficient around 0.90 for biomass burning sites, around 0.77 for dust sites, and below 0.70 for urban sites. The AOD at 500 nm averaged over all sites shows only a small systematic difference between modeled and measured values, with a relative mean bias of 0.02. However, for the AOD at 340 nm the relative mean bias is -0.2. All sites included in the study show a relative mean bias at 340 nm smaller (or more negative) than that at 500 nm, indicating a strong wavelength dependence in the performance of the AOD in the MACC system. A comparison against fine and coarse mode AOD of the AERONET indicates that this has to do with the size distribution of the model: generally, the ECMWF model overestimates the

  17. Comparing ECMWF AOD with AERONET observations at visible and UV wavelengths

    NASA Astrophysics Data System (ADS)

    Cesnulyte, V.; Lindfors, A. V.; Pitkänen, M. R. A.; Lehtinen, K. E. J.; Morcrette, J. J.; Arola, A.

    2013-07-01

    This paper presents validation results of the ECMWF Integrated Forecasting System MACC re-analysis aerosol optical depth (AOD) for the period 2003-2006. We evaluate the MACC AOD at a UV wavelength (340 nm) and at mid-visible (500 and 550 nm) by comparing against ground-based AERONET measurements at 12 sites. The AERONET sites cover various parts of the globe and are categorized in three groups: urban/anthropogenic, biomass burning and dust, depending on the typically dominating aerosol type. This is the first time when a global model such as the ECMWF is evaluated for the performance of AOD at a UV wavelength. The results show that the MACC system generally provides a good representation of the AOD on a monthly basis, showing a realistic seasonal cycle. The model is mostly able to capture major dust load events and also the peak months of biomass burning correctly. For Kanpur and Solar Village, however, the model overestimates the AOD during the monsoon period when the aerosol load is generally low. When comparing hourly AOD values, the model-measurement agreement is better for biomass burning and dust sites than for urban sites, with an average correlation coefficient around 0.90 for biomass burning sites, around 0.77 for dust sites, and below 0.70 for urban sites. The AOD at 500 nm averaged over all sites shows only a small systematic difference between modeled and measured values, with a relative mean bias of 0.02. However, for the AOD at 340 nm the relative mean bias is -0.2. All sites included in the study show a relative mean bias at 340 nm smaller (or more negative) than that at 500 nm, indicating a strong wavelength-dependence in the performance of the AOD in the MACC system. A comparison against fine and coarse mode AOD of the AERONET indicates that this has to do with the size distribution of the model: generally, the ECMWF model overestimates the contribution by coarse mode particles.

  18. 64-MDCT imaging of the coronary arteries and systemic arterial vascular tree in a single examination: optimisation of the scan protocol and contrast-agent administration.

    PubMed

    Napoli, A; Anzidei, M; Francone, M; Cavallo Marincola, B; Carbone, I; Geiger, D; Zaccagna, F; Di Paolo, P L; Zini, C; Catalano, C; Passariello, R

    2008-09-01

    The aim of this study was to validate a 64-row multidetector computed tomography (64-MDCT) acquisition protocol with biphasic administration of contrast medium for comprehensive assessment of the coronary and systemic arterial tree in a single examination. The scanning protocol comprised two acquisitions: an electrocardiograph (ECG)-gated scan at the level of the heart, followed by a total-body, low-dose scan of the systemic arterial circulation. Twenty patients were evaluated using two different strategies for contrast administration. In ten patients, the delay between the two acquisitions was set at 40 s, whereas in the remaining patients, it varied between 45 s and 65 s. For both strategies, the degree of systemic arterial opacification and the attenuation gradient between arterial and venous structures were quantitatively assessed at six extracoronary locations. Two observers evaluated in consensus the presence or absence of atherosclerosis and the degree of stenosis of arterial segments. Three hundred coronary segments were analysed. Arterial-wall changes were depicted in 155 (51%) segments, and in 35 (23%), the degree of stenosis was > 50%. Of the 640 extracoronary arterial segments, 250 (39%) presented atherosclerotic wall alterations, in 50 (20%), the degree of stenosis was > 50% and five were affected by aneurysmal dilatation. The magnitude of arterial opacification values and attenuation gradients between arterial and venous structures were significantly higher in patients scanned with the 40-s fixed-delay strategy. Whole-body CT angiography with biphasic administration of contrast agent and fixed scan delay has been shown to be a feasible and reproducible technique. Comprehensive data on the global atherosclerotic burden potentially offer important therapeutic options for subclinical, high-risk segments.

  19. Comparative observations on levels of mercury in scalp hair of humans from different Islands

    NASA Astrophysics Data System (ADS)

    Renzoni, Aristeo

    1992-09-01

    Following the Minamata events, an extraordinary number of studies concerning mercury toxicity and human health have been undertaken. Particular attention has been given to the evaluation of the dose-response relationship, i.e., the body burden at which (evaluated through the mercury analyses in blood or hair) the risk of poisoning begins. The results of a comparative study concerning levels of mercury in the hair of fishermen living in small islands who eat seafood more than four times per week show that in two areas only, and only in a few cases in these areas, the mercury in the hair exceeds the limit at which a possible risk could exist. In fact, the limit of 50 mg/g of total mercury in the hair (indicated as the lower limit above which a possible risk could occur) is surpassed by nine fishermen out of a total of 39 at station 1 and by four fishermen out of a total of 26 at station 3. The average value at station 1 is 36.38 mg/g and that at station 3 is 30.31 mg. Many countries have set legal limits of mercury for seafood, but evidently the system does not offer a true protection for man. Only the provisional tolerable weekly intake (PTWI), as repeatedly suggested by WHO, should be considered the best guideline to prevent possibly harmful consequences.

  20. Comparing Foreshock Characteristics and Foreshock Forecasting in Observed and Simulated Earthquake Catalogs

    NASA Astrophysics Data System (ADS)

    Ogata, Y.

    2014-12-01

    In our previous papers (Ogata et al., 1995, 1996, 2012; GJI), we characterized foreshock activity in Japan, and then presented a model that forecasts the probability that one or more earthquakes form a foreshock sequence; then we tested prospectively foreshock probabilities in the JMA catalog. In this talk, I compare the empirical results with results for synthetic catalogs in order to clarify whether or not these results are consistent with the description of the seismicity by a superposition of background activity and epidemic-type aftershock sequences (ETAS models). This question is important, because it is still controversially discussed whether the nucleation process of large earthquakes is driven by seismically cascading (ETAS-type) or by aseismic accelerating processes. To explore the foreshock characteristics, I firstly applied the same clustering algorithms to real and synthetic catalogs and analyzed the temporal, spatial and magnitude distributions of the selected foreshocks, to find significant differences particularly in the temporal acceleration and magnitude dependence. Finally, I calculated forecast scores based on a single-link cluster algorithm which could be appropriate for real-time applications. I find that the JMA catalog yields higher scores than all synthetic catalogs and that the ETAS models having the same magnitude sequence as the original catalog performs significantly better (more close to the reality) than ETAS-models with randomly picked magnitudes.

  1. Using Built Environmental Observation Tools: Comparing Two Methods of Creating a Measure of the Built Environment

    PubMed Central

    Keast, Erin M.; Carlson, Nichole E.; Chapman, Nancy J.; Michael, Yvonne L.

    2011-01-01

    Purpose Identify an efficient method of creating a comprehensive and concise measure of the built environment integrating data from geographic information systems (GIS) and the Senior Walking Environmental Assessment Tool (SWEAT). Design Cross-sectional study using a population sample. Setting Eight municipally defined neighborhoods in Portland, Oregon. Subjects Adult residents (N = 120) of audited segments (N = 363). Measures We described built environmental features using SWEAT audits and GIS data. We obtained information on walking behaviors and potential confounders through in-person interviews. Analysis We created two sets of environviental measures, one based on the conceptual framework used to develop SWEAT and another using principal component analysis (PCA). Each measure’s association with walking for transportation and exercise was then assessed and compared using logistic regression. Results A priori measures (destinations, safety, aesthetics, and functionality) and PCA measures (accessibility, comfort/safety, maintenance, and pleasantness) were analogous in conceptual meaning and had similar associations with walking. Walking for transportation was associated with destination accessibility and functional elements, whereas walking for exercise was associated with maintenance of the walking area and protection from traffic. However, only PCA measures consistently reached statistical significance. Conclusion The measures created with PCA were more parsimonious than those created a priori. Performing PCA is an efficient method of combining and scoring SWEAT and GIS data. PMID:20465151

  2. Comparing foreshock characteristics and foreshock forecasting in observed and simulated earthquake catalogs

    NASA Astrophysics Data System (ADS)

    Ogata, Yosihiko; Katsura, Koichi

    2014-11-01

    In this paper, we compare the empirical results regarding foreshocks obtained from the Japan data with results for synthetic catalogs in order to clarify whether or not the corresponding results are consistent with the description of the seismicity by a superposition of background activity and epidemic-type aftershock sequence (ETAS) models. This question is important, because it is still controversially discussed whether the nucleation process of large earthquakes is driven by seismically cascading (ETAS type) or by aseismic accelerating processes. To explore the foreshock characteristics, we first applied the same clustering algorithms to real and synthetic catalogs and analyzed the temporal, spatial, and magnitude distributions of the selected foreshocks. Most properties are qualitatively the same in the real data and in synthetic catalogs. However, we find some quantitative differences particularly in the temporal acceleration, spatial convergence, and magnitude dependence, which also depend on the assumed synthetic catalogs. Furthermore, we calculated forecast scores based on a single-link cluster algorithm which could be appropriate for real-time applications. We find that the Japan Meteorological Agency catalog yields higher scores than all synthetic catalogs and that the ETAS models having the same magnitude sequence as the original catalog performs better (more close to the reality) than ETAS models with randomly picked magnitudes. We also find that the ETAS model that takes account of the triggering effect by small earthquakes below threshold magnitude performs more closely to the reality.

  3. Comparing Goldstone Solar System Radar Earth-based Observations of Mars with Orbital Datasets

    NASA Technical Reports Server (NTRS)

    Haldemann, A. F. C.; Larsen, K. W.; Jurgens, R. F.; Slade, M. A.

    2005-01-01

    The Goldstone Solar System Radar (GSSR) has collected a self-consistent set of delay-Doppler near-nadir radar echo data from Mars since 1988. Prior to the Mars Global Surveyor (MGS) Mars Orbiter Laser Altimeter (MOLA) global topography for Mars, these radar data provided local elevation information, along with radar scattering information with global coverage. Two kinds of GSSR Mars delay-Doppler data exist: low 5 km x 150 km resolution and, more recently, high (5 to 10 km) spatial resolution. Radar data, and non-imaging delay-Doppler data in particular, requires significant data processing to extract elevation, reflectivity and roughness of the reflecting surface. Interpretation of these parameters, while limited by the complexities of electromagnetic scattering, provide information directly relevant to geophysical and geomorphic analyses of Mars. In this presentation we want to demonstrate how to compare GSSR delay-Doppler data to other Mars datasets, including some idiosyncracies of the radar data. Additional information is included in the original extended abstract.

  4. Technology assessment: observer study directly compares screen/film to CR mammography

    NASA Astrophysics Data System (ADS)

    Fletcher-Heath, Lynn; Richards, Anne; Ryan-Kron, Susan

    2007-03-01

    A new study supports and expands upon a previous reporting that computed radiography (CR) mammography offers as good, or better, image quality than state-of-the-art screen/film mammography. The suitability of CR mammography is explored through qualitative and quantitative study components: feature comparison and cancer detection rates of each modality. Images were collected from 150 normal and 50 biopsy-confirmed subjects representing a range of breast and pathology types. Comparison views were collected without releasing compression, using automatic exposure control on Kodak MIN-R films, followed by CR. Digital images were displayed as both softcopy (S/C) and hardcopy (H/C) for the feature comparison, and S/C for the cancer detection task. The qualitative assessment used preference scores from five board-certified radiologists obtained while viewing 100 screen/film-CR pairs from the cancer subjects for S/C and H/C CR output. Fifteen general image-quality features were rated, and up to 12 additional features were rated for each pair, based on the pathology present. Results demonstrate that CR is equivalent or preferred to conventional mammography for overall image quality (89% S/C, 95% H/C), image contrast (95% S/C, 98% H/C), sharpness (86% S/C, 93% H/C), and noise (94% S/C, 91% H/C). The quantitative objective was satisfied by asking 10 board-certified radiologists to provide a BI-RADS TM score and probability of malignancy per breast for each modality of the 200 cases. At least 28 days passed between observations of the same case. Average sensitivity and specificity was 0.89 and 0.82 for CR and 0.91 and 0.82 for screen/film, respectively.

  5. LIVVkit 2: An extensible land ice verification and validation toolkit for comparing observations and models?

    NASA Astrophysics Data System (ADS)

    Kennedy, J. H.; Bennett, A. R.; Evans, K. J.; Fyke, J. G.; Vargo, L.; Price, S. F.; Hoffman, M. J.

    2016-12-01

    Accurate representation of ice sheets and glaciers are essential for robust predictions of arctic climate within Earth System models. Verification and Validation (V&V) is a set of techniques used to quantify the correctness and accuracy of a model, which builds developer/modeler confidence, and can be used to enhance the credibility of the model. Fundamentally, V&V is a continuous process because each model change requires a new round of V&V testing. The Community Ice Sheet Model (CISM) development community is actively developing LIVVkit, the Land Ice Verification and Validation toolkit, which is designed to easily integrate into an ice-sheet model's development workflow (on both personal and high-performance computers) to provide continuous V&V testing.LIVVkit is a robust and extensible python package for V&V, which has components for both software V&V (construction and use) and model V&V (mathematics and physics). The model Verification component is used, for example, to verify model results against community intercomparisons such as ISMIP-HOM. The model validation component is used, for example, to generate a series of diagnostic plots showing the differences between model results against observations for variables such as thickness, surface elevation, basal topography, surface velocity, surface mass balance, etc. Because many different ice-sheet models are under active development, new validation datasets are becoming available, and new methods of analysing these models are actively being researched, LIVVkit includes a framework to easily extend the model V&V analyses by ice-sheet modelers. This allows modelers and developers to develop evaluations of parameters, implement changes, and quickly see how those changes effect the ice-sheet model and earth system model (when coupled). Furthermore, LIVVkit outputs a portable hierarchical website allowing evaluations to be easily shared, published, and analysed throughout the arctic and Earth system communities.

  6. Multicenter, Phase 3 Trial Comparing Selenium Supplementation With Observation in Gynecologic Radiation Oncology

    SciTech Connect

    Muecke, Ralph; Schomburg, Lutz; Glatzel, Michael; Berndt-Skorka, Regina; Baaske, Dieter; Reichl, Berthold; Buentzel, Jens; Kundt, Guenter; Prott, Franz J.; Vries, Alexander de; Stoll, Guenther; Kisters, Klaus; Bruns, Frank; Schaefer, Ulrich; Willich, Norman; Micke, Oliver

    2010-11-01

    Purpose: We assessed whether adjuvant supplementation with selenium improves the selenium status and reduces side effects of patients treated by radiotherapy (RT) for cervical and uterine cancer. Methods and Materials: Whole-blood selenium concentrations were measured in patients with cervical cancer (n = 11) and uterine cancer (n = 70) after surgical treatment, during RT, at the end of RT, and 6 weeks after RT. Patients with initial selenium concentrations of less than 84{mu}g/L were randomized before RT either to receive 500 {mu}g of selenium (in the form of sodium selenite [selenase (registered) , biosyn Arzneimittel GmbH, Fellbach, Germany]) by mouth on the days of RT and 300 {mu}g of selenium on the days without RT or to receive no supplement during RT. The primary endpoint of this multicenter Phase 3 study was to assess the efficiency of selenium supplementation during RT; the secondary endpoint was to decrease radiation-induced diarrhea and other RT-dependent side effects. Results: A total of 81 patients were randomized. We enrolled 39 in the selenium group (SG) and 42 in the control group (CG). Selenium levels did not differ between the SG and CG upon study initiation but were significantly higher in the SG at the end of RT. The actuarial incidence of diarrhea of Grade 2 or higher according to Common Toxicity Criteria (version 2) in the SG was 20.5% compared with 44.5% in the CG (p = 0.04). Other blood parameters, Eastern Cooperative Oncology Group performance status, and self-reported quality of life were not different between the groups. Conclusions: Selenium supplementation during RT is effective in improving blood selenium status in selenium-deficient cervical and uterine cancer patients and reduces the number of episodes and severity of RT-induced diarrhea.

  7. Predicted interplanetary shocks/particles at Mars compared with in-situ observations: An overview

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, Susan M. P.

    2008-11-01

    The biological and technological consequences of long-duration, solar-related, energetic particle radiation for manned/unmanned spacecraft warrant that consideration be given to providing reliable space weather predictions for future space missions to planet Mars. An account is, herein, provided of how the HAFv.2 numerical model was applied to predict the arrivals of four, flare-related, shocks at Mars generated during a >20-day active period on the Sun in March 1989, and of the arrival of another composite shock produced in association with a 10-day period of solar activity in December 2006. These predictions are compared with in-situ measurements of shock signatures at Mars recorded, in the former case, by the solar-low-energy-detector (SLED) and by the low-energy-telescope (LET) aboard the Phobos-2 spacecraft and, in the latter case, in data recorded by the ASPERA-3/IMA instrument aboard Mars Express. The success of the predictions is discussed and the requirement for further validation of the modeling technique using a large statistical sample pointed out. In-situ measurements made aboard Mars Express by the ASPERA-3/IMA experiment during the rising phase of Solar Cycle 24 can provide data relevant to such validation. The successful application of a SOLar Particle ENgineering COde (SOLPENCO), that estimates solar energetic particle (SEP) fluxes and fluences at the Earth, to the case of an energetic particle event at Mars (6 March 1989) is discussed. Measurements of SEP events recorded by the Solar TErrestrial RElations Observatory (STEREO) supplemented by Mars Express measurements can potentially allow the predictions of SOLPENCO to be further studied downstream using a large statistical sample. However, we are presently only at the beginning of our understanding of the complex Sun-Earth-Mars scenarios that give rise to shock/particle events in the close Martian environment.

  8. Correlating MDCT Liver Injury Grade and Clinical Outcome in Patients Without Significant Extra-hepatic Injury.

    PubMed

    Kumar, Ravi; Kumar, Atin; Baliyan, Vinit; Gamanagatti, Shivanand; Bhalla, Ashu Seith; Sharma, Raju; Gupta, Amit; Kumar, Subodh; Misra, M C

    2016-08-01

    The aim of the study was to correlate multi-detector computed tomography (MDCT) grading with clinical severity and outcome in liver trauma patients without significant extrahepatic injury. Over a period of 2 years (2011-2013), all patients showing evidence of liver injury on contrast-enhanced CT (CECT) abdomen and without significant extrahepatic trauma were prospectively included in the study. Correlation between the CT injury grade and outcome in terms of mortality, duration of ICU/hospital stay, fluid and blood requirements, need for intervention and complications were assessed. The significance of the difference in mortality, duration of ICU/hospital stay, fluid requirement and blood requirements among the patients with various injury grades was assessed by Kruskal-Wallis test. The significance of the difference in need for intervention and complications among the patients with various injury grades was assessed by Fisher's exact test. A total of 198 patients were found to have evidence of hepatic injury on CECT. Out of 198 patients, 117 had insignificant extrahepatic trauma. The overall mean age for these 117 patients was 25.74 ± 15.53 (age range 2-84 years). Death rates according to AAST grades were 0 % in grades II and III, 6.89 % in grade IV and 9.09 % in grade V (p = 0.053). The mean ICU and total hospital stay for grade II was 1.32 and 5.91 days, for grade III was 1.76 and 8.48, for grade IV was 2.86 and 10.31 days and for grade V was 6.54 and 12 days, respectively (p = 0.0001 for ICU, p = 0.0003 for total stay). Mean input and fluid deficit according to various grades were 8634/2607 ml for grade II, 9535/2555 ml for grade III, 15,549/6242 ml for grade IV and 19,958/8280 ml for grade V (p value input-0.0016, output-input (fluid deficit)-0.0001). Average unit of RBC and sum of the blood products transfused were 1.73 and 2.26 for grade II, 2.18 and 2.72 for grade III, 3.03 and 6.27 for grade IV, 6.85 and 38.12 for grade V

  9. Key Process Uncertainties in Soil Carbon Dynamics: Comparing Multiple Model Structures and Observational Meta-analysis

    NASA Astrophysics Data System (ADS)

    Sulman, B. N.; Moore, J.; Averill, C.; Abramoff, R. Z.; Bradford, M.; Classen, A. T.; Hartman, M. D.; Kivlin, S. N.; Luo, Y.; Mayes, M. A.; Morrison, E. W.; Riley, W. J.; Salazar, A.; Schimel, J.; Sridhar, B.; Tang, J.; Wang, G.; Wieder, W. R.

    2016-12-01

    Soil carbon (C) dynamics are crucial to understanding and predicting C cycle responses to global change and soil C modeling is a key tool for understanding these dynamics. While first order model structures have historically dominated this area, a recent proliferation of alternative model structures representing different assumptions about microbial activity and mineral protection is providing new opportunities to explore process uncertainties related to soil C dynamics. We conducted idealized simulations of soil C responses to warming and litter addition using models from five research groups that incorporated different sets of assumptions about processes governing soil C decomposition and stabilization. We conducted a meta-analysis of published warming and C addition experiments for comparison with simulations. Assumptions related to mineral protection and microbial dynamics drove strong differences among models. In response to C additions, some models predicted long-term C accumulation while others predicted transient increases that were counteracted by accelerating decomposition. In experimental manipulations, doubling litter addition did not change soil C stocks in studies spanning as long as two decades. This result agreed with simulations from models with strong microbial growth responses and limited mineral sorption capacity. In observations, warming initially drove soil C loss via increased CO2 production, but in some studies soil C rebounded and increased over decadal time scales. In contrast, all models predicted sustained C losses under warming. The disagreement with experimental results could be explained by physiological or community-level acclimation, or by warming-related changes in plant growth. In addition to the role of microbial activity, assumptions related to mineral sorption and protected C played a key role in driving long-term model responses. In general, simulations were similar in their initial responses to perturbations but diverged over

  10. Comparing Stable Water Isotope Variation in Atmospheric Moisture Observed over Coastal Water and Forests

    NASA Astrophysics Data System (ADS)

    Lai, C. T.; Rambo, J. P.; Welp, L. R.; Bible, K.; Hollinger, D. Y.

    2014-12-01

    Stable oxygen (δ18O) and hydrogen (δD) isotopologues of atmospheric moisture are strongly influenced by large-scale synoptic weather cycles, surface evapotranspiration and boundary layer mixing. Atmospheric water isotope variation has been shown to empirically relate to relative humidity (Rh) of near surface moisture, and to a less degree, air temperature. Continuous δ18O and δD measurements are becoming more available, providing new opportunities to investigate processes that control isotope variability. This study shows the comparison of δ18O and δD measured at a continental location and over coastal waters for 3 seasons (spring to fall, 2014). The surface moisture isotope measurements were made using two LGR spectroscopy water vapor isotope analyzers (Los Gatos Research Inc.), one operated in an old-growth coniferous forest at Wind River field station, WA (45.8205°N, 121.9519°W), and another sampling marine air over seawater at the Scripps Pier in San Diego, CA (32.8654°N, 117.2536°W), USA. Isotope variations were measured at 1Hz and data were reported as hourly averages with an overall accuracy of ±0.1‰ for δ18O, ±0.5‰ for δ2H. Day-to-day variations in δ18O and δD are shown strongly influenced by synoptic weather events at both locations. Boundary layer mixing between surface moisture and the dry air entrained from the free troposphere exerts a midday maximum and a consistent diel pattern in deuterium excess (dx). At the forest site, surface moisture also interacts with leaf water through transpiration during the day and re-equilibration at night. The latter occurs by retro-diffusion of atmospheric H2O molecules into leaf intercellular space, which becomes intensified as Rh increaes after nightfall, and continues until sunrise, to counter-balance the evaporative isotopic enrichment in leaf water on a daily basis. These vegetation effects lead to negative dx values consistently observed at nighttime in this continental location that were not

  11. Interannual sedimentary effluxes of alkalinity in the southern North Sea: Model results compared with summer observations.

    NASA Astrophysics Data System (ADS)

    Paetsch, Johannes; Kuehn, Wilfried; Six, Katharina

    2016-04-01

    Alkalinity generation in the sediment of the southern North Sea is the focus of several recent studies. One motivation for these efforts is the potentially enhanced buffering capacity of anthropogenic CO2 invasion into the corresponding pelagic system. An adaptation of a global multilayer sediment model (Heinze et al., 1999) in combination with a pelagic ecosystem model for shelf sea dynamics was used to study the benthic reactions on very different annual cycles (2001 - 2009) including the River Elbe summer flooding in 2002. The focus of this study is the efflux of alkalinity, their different contributors (aerobic respiration, denitrification, net sulfate reduction, calcite dissolution, nitrification) and their seasonal and interannual cycles. Similar to the observations covering the southern North Sea (Brenner et al., 2015) the model results show large horizontal gradients from the near-shore high productive areas with benthic remineralization up to Rmin = 10.6 mol C m-2 yr-1 and TA generation RTA = 2 mol C m-2 yr-1 to off-shore moderate productive areas with mean Rmin = 2.5 mol C m-2 yr-1 and mean TA generation RTA = 0.4 mol C m-2 yr-1. Beside calcite dissolution, aerobic respiration (producing ammonium) and denitrification are the largest contributors to alkalinity generation. Nitrification is reducing alkalinity in the sediment. Due to low regenerated primary production in summer, the year 2001 exhibits the lowest input of particulate organic matter into the sediment (POCexp=2.3 mol C m-2 yr-1), while the year 2003 exhibits the highest export production (POCexp=2.6 mol C m-2 yr-1). The biogeochemical reactions and the effluxes from the sediment follow these pelagic amplitudes with a time lag of about one year with damped amplitudes. References Brenner, H., Braeckman, U., Le Guitton, M., Meysman, F.J.R., 2015. The impact of sedimentary alkalinity release on the water column CO2 system in the North Sea. Biogeosiences Discussion, 12(15): 12395-12453. Heinze, C

  12. Reduction in accuracy of genomic prediction for ordered categorical data compared to continuous observations

    PubMed Central

    2014-01-01

    Background Accuracy of genomic prediction depends on number of records in the training population, heritability, effective population size, genetic architecture, and relatedness of training and validation populations. Many traits have ordered categories including reproductive performance and susceptibility or resistance to disease. Categorical scores are often recorded because they are easier to obtain than continuous observations. Bayesian linear regression has been extended to the threshold model for genomic prediction. The objective of this study was to quantify reductions in accuracy for ordinal categorical traits relative to continuous traits. Methods Efficiency of genomic prediction was evaluated for heritabilities of 0.10, 0.25 or 0.50. Phenotypes were simulated for 2250 purebred animals using 50 QTL selected from actual 50k SNP (single nucleotide polymorphism) genotypes giving a proportion of causal to total loci of.0001. A Bayes C π threshold model simultaneously fitted all 50k markers except those that represented QTL. Estimated SNP effects were utilized to predict genomic breeding values in purebred (n = 239) or multibreed (n = 924) validation populations. Correlations between true and predicted genomic merit in validation populations were used to assess predictive ability. Results Accuracies of genomic estimated breeding values ranged from 0.12 to 0.66 for purebred and from 0.04 to 0.53 for multibreed validation populations based on Bayes C π linear model analysis of the simulated underlying variable. Accuracies for ordinal categorical scores analyzed by the Bayes C π threshold model were 20% to 50% lower and ranged from 0.04 to 0.55 for purebred and from 0.01 to 0.44 for multibreed validation populations. Analysis of ordinal categorical scores using a linear model resulted in further reductions in accuracy. Conclusions Threshold traits result in markedly lower accuracy than a linear model on the underlying variable. To achieve an accuracy equal or

  13. Comparing ligo merger rate observations with theory: distribution of star-forming conditions

    SciTech Connect

    Belczynski, Kryzysztof; Kopparapu, R; O' Shaughnessy, R

    2008-01-01

    -forming conditions depends on the binary evolution model and on the amount of relevant variation in star-forming conditions. For example, if after further comparison with electromagnetic and gravitational wave observations future population synthesis models suggest all BH-BH binary mergers occur promptly and therefore are associated with well-studied present-day star formation, the associated composition-related systematic uncertainty could be lower than the pessimistic value quoted above. Further, as gravitational wave detectors will make available many properties of each merger -- binary component masses, spins, and even short GRB associations and host galaxies could be available -- many detections can still be exploited to create high-precision constraints on binary compact object formation models.

  14. Comparing nutritional requirements, provision and intakes among patients prescribed therapeutic diets in hospital: An observational study.

    PubMed

    Rattray, Megan; Desbrow, Ben; Roberts, Shelley

    Nutrition is an important part of recovery for hospitalized patients. The aim of this study was to assess the nutritional adequacy of meals provided to and consumed by patients prescribed a therapeutic diet. Patients (N = 110) prescribed a therapeutic diet (texture-modified, low-fiber, oral fluid, or food allergy or intolerance diets) for medical or nutritional reasons were recruited from six wards of a tertiary hospital. Complete (24-h) dietary provisions and intakes were directly observed and analyzed for energy (kJ) and protein (g) content. A chart audit gathered demographic, clinical, and nutrition-related information to calculate each patient's disease-specific estimated energy and protein requirements. Provisions and intake were considered adequate if they met ≥75% of the patient's estimated requirements. Mean energy and protein provided to patients (5844 ± 2319 kJ, 53 ± 30 g) were significantly lower than their mean estimated requirements (8786 ± 1641 kJ, 86 ± 18 g). Consequently, mean nutrition intake (4088 ± 2423 kJ, 37 ± 28 g) were significantly lower than estimated requirements. Only 37% (41) of patients were provided with and 18% (20) consumed adequate nutrition to meet their estimated requirements. No therapeutic diet provided adequate food to meet the energy and protein requirements of all recipients. Patients on oral fluid diets had the highest estimated requirements (9497 ± 1455 kJ, 93 ± 16 g) and the lowest nutrient provision (3497 ± 1388 kJ, 25 ± 19 g) and intake (2156 ± 1394 kJ, 14 ± 14 g). Hospitalized patients prescribed therapeutic diets (particularly fluid-only diets) are at risk for malnutrition. Further research is required to determine the most effective strategies to improve nutritional provision and intake among patients prescribed therapeutic diets. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Patient satisfaction with primary care: an observational study comparing anthroposophic and conventional care

    PubMed Central

    Esch, Barbara M; Marian, Florica; Busato, André; Heusser, Peter

    2008-01-01

    Background This study is part of a cross-sectional evaluation of complementary medicine providers in primary care in Switzerland. It compares patient satisfaction with anthroposophic medicine (AM) and conventional medicine (CON). Methods We collected baseline data on structural characteristics of the physicians and their practices and health status and demographics of the patients. Four weeks later patients assessed their satisfaction with the received treatment (five items, four point rating scale) and evaluated the praxis care (validated 23-item questionnaire, five point rating scale). 1946 adult patients of 71 CON and 32 AM primary care physicians participated. Results 1. Baseline characteristics: AM patients were more likely female (75.6% vs. 59.0%, p < 0.001) and had higher education (38.6% vs. 24.7%, p < 0.001). They suffered more often from chronic illnesses (52.8% vs. 46.2%, p = 0.015) and cancer (7.4% vs. 1.1%). AM consultations lasted on average 23,3 minutes (CON: 16,8 minutes, p < 0.001). 2. Satisfaction: More AM patients expressed a general treatment satisfaction (56.1% vs. 43.4%, p < 0.001) and saw their expectations completely fulfilled at follow-up (38.7% vs. 32.6%, p < 0.001). AM patients reported significantly fewer adverse side effects (9.3% vs. 15.4%, p = 0.003), and more other positive effects from treatment (31.7% vs. 17.1%, p < 0.001). Europep: AM patients appreciated that their physicians listened to them (80.0% vs. 67.1%, p < 0.001), spent more time (76.5% vs. 61.7%, p < 0.001), had more interest in their personal situation (74.6% vs. 60.3%, p < 0.001), involved them more in decisions about their medical care (67.8% vs. 58.4%, p = 0.022), and made it easy to tell the physician about their problems (71.6% vs. 62.9%, p = 0.023). AM patients gave significantly better rating as to information and support (in 3 of 4 items p [less than or equal to] 0.044) and for thoroughness (70.4% vs. 56.5%, p < 0.001). Conclusion AM patients were significantly

  16. Assessing conflict communication in couples: comparing the validity of self-report, partner-report, and observer ratings.

    PubMed

    Sanford, Keith

    2010-04-01

    This study of married couples investigated the short-term predictive validity of the partner-report and self-report scales of the Conflict Communication Inventory and compared the validity of these scales with the validity of observer ratings. A sample of 83 married couples completed two problem-solving conversations. Self-report, partner-report, and observer ratings from Conversation 1 were used to predict behavior in Conversation 2, as rated by a separate panel of observers. The short-term predictive validity of partner-report ratings was extremely high and indistinguishable from the validity of observer ratings. Self-report ratings also demonstrated good validity, albeit slightly lower than other methods. Both partner-report and self-report scores explained a substantial amount of variance in concurrent observer ratings of communication after controlling for relationship satisfaction. 2010 APA, all rights reserved

  17. How Physicians, Patients, and Observers Compare on the Use of Qualitative and Quantitative Measures of Physician-Patient Communication.

    PubMed

    Gordon, Howard S; Street, Richard L

    2016-12-01

    The purpose of this study was to compare several different measures of physician-patient communication. We compared data derived from different measures of three communication behaviors, patient participation, physician information giving, and physician participatory decision-making (PDM) style, from 83 outpatient visits to oncology or thoracic surgery clinics for pulmonary nodules or lung cancer. Communication was measured with rating scales completed by patients and physicians after the consultation and by two different groups of external observers who used rating scales or coded the frequency of communication behaviors, respectively, after listening to an audio recording of the consultation. Measures were compared using Pearson's correlations. Correlations of patients' and physicians' ratings of patient participation (r = .04) and physician PDM style (r = .03) were low and not significant (p > .0083, Bonferroni-adjusted). Correlations of observers' ratings with patients' or physicians' ratings for patient participation and physician PDM style were moderate or low (r = .15, .27, .07, and .01, respectively) but were not statistically significant (p > .0083, Bonferroni-adjusted). Correlations between observers' ratings and frequency measures were .31, .52, and .63 and were statistically significant with p values .005, <.0001, and <.0001, respectively, for PDM style, information giving, and patient participation. Our findings highlight the potential for using observers' ratings as an alternate measure of communication to more labor intensive frequency measures.

  18. Efficiency of the human observer compared to an ideal observer based on a generalized NEQ which incorporates scatter and geometric unsharpness: evaluation with a 2AFC experiment

    NASA Astrophysics Data System (ADS)

    Kyprianou, Iacovos S.; Ganguly, Arundhuti; Rudin, Stephen; Bednarek, Daniel R.; Gallas, Brandon D.; Myers, Kyle J.

    2005-04-01

    Under certain assumptions the detectability of the ideal observer can be defined as the integral of the system Noise Equivalent Quanta multiplied by the squared object spatial frequency distribution. Using the detector Noise-Equivalent-Quanta (NEQD) for the calculation of detectability inadequately describes the performance of an x-ray imaging system because it does not take into account the effects of patient scatter and geometric unsharpness. As a result, the ideal detectability index is overestimated, and hence the efficiency of the human observer in detecting objects is underestimated. We define a Generalized-NEQ (GNEQ) for an x-ray system referenced at the object plane that incorporates the scatter fraction, the spatial distributions of scatter and focal spot, the detector MTFD, and the detector Normalized-Noise-Power-Spectrum (NNPSD). This GNEQ was used in the definition of the ideal detectability for the evaluation of the human observer efficiency during a two Alternative Forced Choice (2-AFC) experiment, and was compared with the case where only the NEQD was used in the detectability calculations. The 2-AFC experiment involved the detection of images of polyethylene tubes (diameters between 100-300 um) filled with iodine contrast (concentrations between 0-120 mg/cm3) placed onto a uniform head equivalent phantom placed near the surface of a microangiographic detector (43 um pixel size). The resulting efficiency of the human observer without regarding the effects of scatter and geometric unsharpness was 30%. When these effects were considered the efficiency was increased to 70%. The ideal observer with the GNEQ can be a simple optimization method of a complete imaging system.

  19. Efficiency of the Human Observer Compared to an Ideal Observer Based on a Generalized NEQ Which Incorporates Scatter and Geometric Unsharpness: Evaluation with a 2AFC Experiment.

    PubMed

    Kyprianou, Iacovos S; Ganguly, Arundhuti; Rudin, Stephen; Bednarek, Daniel R; Gallas, Brandon D; Myers, Kyle J

    2005-01-01

    Under certain assumptions the detectability of the ideal observer can be defined as the integral of the system Noise Equivalent Quanta multiplied by the squared object spatial frequency distribution. Using the detector Noise-Equivalent-Quanta (NEQ(D)) for the calculation of detectability inadequately describes the performance of an x-ray imaging system because it does not take into account the effects of patient scatter and geometric unsharpness. As a result, the ideal detectability index is overestimated, and hence the efficiency of the human observer in detecting objects is underestimated. We define a Generalized-NEQ (GNEQ) for an x-ray system referenced at the object plane that incorporates the scatter fraction, the spatial distributions of scatter and focal spot, the detector MTF(D), and the detector Normalized-Noise-Power-Spectrum (NNPS(D)). This GNEQ was used in the definition of the ideal detectability for the evaluation of the human observer efficiency during a two Alternative Forced Choice (2-AFC) experiment, and was compared with the case where only the NEQ(D) was used in the detectability calculations. The 2-AFC experiment involved the detection of images of polyethylene tubes (diameters between 100-300 μm) filled with iodine contrast (concentrations between 0-120 mg/cm(3)) placed onto a uniform head equivalent phantom placed near the surface of a microangiographic detector (43 μm pixel size). The resulting efficiency of the human observer without regarding the effects of scatter and geometric unsharpness was 30%. When these effects were considered the efficiency was increased to 70%. The ideal observer with the GNEQ can be a simple optimization method of a complete imaging system.

  20. Efficiency of the Human Observer Compared to an Ideal Observer Based on a Generalized NEQ Which Incorporates Scatter and Geometric Unsharpness: Evaluation with a 2AFC Experiment

    PubMed Central

    Kyprianou, Iacovos S.; Ganguly, Arundhuti; Rudin, Stephen; Bednarek, Daniel R.; Gallas, Brandon D.; Myers, Kyle J.

    2011-01-01

    Under certain assumptions the detectability of the ideal observer can be defined as the integral of the system Noise Equivalent Quanta multiplied by the squared object spatial frequency distribution. Using the detector Noise-Equivalent-Quanta (NEQD) for the calculation of detectability inadequately describes the performance of an x-ray imaging system because it does not take into account the effects of patient scatter and geometric unsharpness. As a result, the ideal detectability index is overestimated, and hence the efficiency of the human observer in detecting objects is underestimated. We define a Generalized-NEQ (GNEQ) for an x-ray system referenced at the object plane that incorporates the scatter fraction, the spatial distributions of scatter and focal spot, the detector MTFD, and the detector Normalized-Noise-Power-Spectrum (NNPSD). This GNEQ was used in the definition of the ideal detectability for the evaluation of the human observer efficiency during a two Alternative Forced Choice (2-AFC) experiment, and was compared with the case where only the NEQD was used in the detectability calculations. The 2-AFC experiment involved the detection of images of polyethylene tubes (diameters between 100–300 μm) filled with iodine contrast (concentrations between 0–120 mg/cm3) placed onto a uniform head equivalent phantom placed near the surface of a microangiographic detector (43 μm pixel size). The resulting efficiency of the human observer without regarding the effects of scatter and geometric unsharpness was 30%. When these effects were considered the efficiency was increased to 70%. The ideal observer with the GNEQ can be a simple optimization method of a complete imaging system. PMID:21311735

  1. Transitive and intransitive gesture execution and observation compared to resting state: the hemodynamic measures (fNIRS).

    PubMed

    Balconi, Michela; Vanutelli, Maria Elide; Bartolo, Angela; Cortesi, Livia

    2015-09-01

    The present study explored cortical correlates of gesture execution and observation in peripersonal space, using functional near-infrared spectroscopy (fNIRS). Moreover, a direct comparison was realized between resting state condition and execution/observation. Meaningful gestures produced in the presence (transitive action) or in the absence (intransitive action) of the object were considered in a real context (situated representation of gestures). Subjects were required to execute or observe transitive versus intransitive gestures during fNIRS registration. Gesture execution was related to higher brain activity (increased oxygenated hemoglobin levels) with respect to observation in motor areas (premotor cortex, PMC; supplementary motor cortex, SM1). In contrast, the posterior parietal cortex was similarly activated in case of both execution and observation task. Moreover, both tasks showed increased brain activity within these areas compared to resting state. Finally, it was shown that action execution and observation of transitive gestures was supported by similar parietal posterior areas. These findings support the hypothesis of a partial common network for observation and execution of gestures within peripersonal space, mainly in transitive condition.

  2. A Comparative Experimental Study of an Extreme Rainstorm Caused by the Southwest China Vortex during the Intensive Observation Period

    NASA Astrophysics Data System (ADS)

    Cheng, X.

    2016-12-01

    Abstract A rainstorm caused by the Southwest China vortex (SWCV) in Sichuan during 7 July-10 July 2012 is analyzed by using the NCEP data of 1ºx1º with 6-hour interval, the conventional observed data and the intensive observed data of SWCV experiment during flood season. The results show that using the Southwest Center - WRF ADAS Real-time Modeling System (SWCWARMS), compared with the control experiment, the distribution of rainfall in assimilation experiment (only assimilating intensive observed data) is more similar to the actual precipitation. By assimilating intensive observed data, the southerly flow exists in northern Sichuan in initial time, which benefits for the newborn of SWCV. Contrast research shows the strength and the range of SWCV are much larger than them in control experiment. In addition, there is a phenomenon that airflow heaps up at the south side of Daba Mountain due to the blocking function of terrain, which causes rainstorm at the border of Sichuan and Shanxi. So, assimilating the intensive observed data in regional modeling system can improve the weather forecast of heavy rainfall and promote the predict ability of SWCV. Key words: Intensive observation, Southwest China vortex, Rainstorm

  3. Learning by viewing versus learning by doing: A comparative study of observer and participant experiences during an interprofessional simulation training.

    PubMed

    Reime, Marit Hegg; Johnsgaard, Tone; Kvam, Fred Ivan; Aarflot, Morten; Engeberg, Janecke Merethe; Breivik, Marit; Brattebø, Guttorm

    2017-01-01

    Larger student groups and pressure on limited faculty time have raised the question of the learning value of merely observing simulation training in emergency medicine, instead of active team participation. The purpose of this study was to examine observers and hands-on participants' self-reported learning outcomes during simulation-based interprofessional team training regarding non-technical skills. In addition, we compared the learning outcomes for different professions and investigated team performance relative to the number of simulations in which they participated. A concurrent mixed-method design was chosen to evaluate the study, using questionnaires, observations, and focus group interviews. Participants included a total of 262 postgraduate and bachelor nursing students and medical students, organised into 44 interprofessional teams. The quantitative data showed that observers and participants had similar results in three of six predefined learning outcomes. The qualitative data emphasised the importance of participating in different roles, training several times, and training interprofessionally to enhance realism. Observing simulation training can be a valuable learning experience, but the students' preferred hands-on participation and learning by doing. For this reason, one can legitimise the observer role, given the large student groups and limited faculty time, as long as the students are also given some opportunity for hands-on participation in order to become more confident in their professional roles.

  4. Comparing nadir and limb observations of polar mesospheric clouds: The effect of the assumed particle size distribution

    NASA Astrophysics Data System (ADS)

    Bailey, Scott M.; Thomas, Gary E.; Hervig, Mark E.; Lumpe, Jerry D.; Randall, Cora E.; Carstens, Justin N.; Thurairajah, Brentha; Rusch, David W.; Russell, James M.; Gordley, Larry L.

    2015-05-01

    Nadir viewing observations of Polar Mesospheric Clouds (PMCs) from the Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere (AIM) spacecraft are compared to Common Volume (CV), limb-viewing observations by the Solar Occultation For Ice Experiment (SOFIE) also on AIM. CIPS makes multiple observations of PMC-scattered UV sunlight from a given location at a variety of geometries and uses the variation of the radiance with scattering angle to determine a cloud albedo, particle size distribution, and Ice Water Content (IWC). SOFIE uses IR solar occultation in 16 channels (0.3-5 μm) to obtain altitude profiles of ice properties including the particle size distribution and IWC in addition to temperature, water vapor abundance, and other environmental parameters. CIPS and SOFIE made CV observations from 2007 to 2009. In order to compare the CV observations from the two instruments, SOFIE observations are used to predict the mean PMC properties observed by CIPS. Initial agreement is poor with SOFIE predicting particle size distributions with systematically smaller mean radii and a factor of two more albedo and IWC than observed by CIPS. We show that significantly improved agreement is obtained if the PMC ice is assumed to contain 0.5% meteoric smoke by mass, in agreement with previous studies. We show that the comparison is further improved if an adjustment is made in the CIPS data processing regarding the removal of Rayleigh scattered sunlight below the clouds. This change has an effect on the CV PMC, but is negligible for most of the observed clouds outside the CV. Finally, we examine the role of the assumed shape of the ice particle size distribution. Both experiments nominally assume the shape is Gaussian with a width parameter roughly half of the mean radius. We analyze modeled ice particle distributions and show that, for the column integrated ice distribution, Log-normal and Exponential distributions better represent the range

  5. Comparing the Predictive Capacity of Observed In-Session Resistance to Self-Reported Motivation in Cognitive Behavioral Therapy

    PubMed Central

    Westra, Henny A.

    2010-01-01

    Self-report measures of motivation for changing anxiety have been weakly and inconsistently related to outcome in cognitive behavioral therapy (CBT). While clients may not be able to accurately report their motivation, ambivalence about change may nonetheless be expressed in actual therapy sessions as opposition to the direction set by the therapist (i.e., resistance). In the context of CBT for generalized anxiety disorder, the present study compared the ability of observed in-session resistance in CBT session 1 and two self-report measures of motivation for changing anxiety (the Change Questionnaire & the Client Motivational for Therapy Scale) to (1) predict client and therapist rated homework compliance (2) predict post-CBT and one-year post-treatment worry reduction, and (3) differentiate those who received motivational interviewing prior to CBT from those who received no pretreatment. Observed in-session resistance performed very well on each index, compared to the performance of self-reported motivation which was inconsistent and weaker relative to observed resistance. These findings strongly support both clinician sensitivity to moments of client resistance in actual therapy sessions as early as session 1, and the inclusion of observational process measures in CBT research. PMID:21159325

  6. Are Common Skin Diseases among Norwegian Dermatological Outpatients Associated with Psychological Problems Compared with Controls? An Observational Study.

    PubMed

    Balieva, Flora; Lien, Lars; Kupfer, Jörg; Halvorsen, Jon Anders; Dalgard, Florence

    2016-02-01

    Dermatological disease has been shown to be associated with psychological comorbidity. The aim of this observational study is to describe the distribution of skin disease and the prevalence of depression, anxiety and stress among Norwegian dermatological outpatients. Thirteen percent of outpatients had clinical anxiety compared with 3.7% of healthy controls, and 5.8% had clinical depression compared with 0.9% of controls. Adjusted odds ratio for clinical anxiety was 4.53 in patients compared with controls, and for clinical depression 6.25, which is much higher than previously described in a larger European study. Patients with tumours had less depression. Chronic inflammatory skin conditions had an especially high impact on patient's psychological wellbeing and should not be undervalued relative to, for instance, skin cancer in health strategies. These results argue strongly for including skin disease prevention and treatment in future health strategies.

  7. Radiological surveillance of formerly asbestos-exposed power industry workers: rates and risk factors of benign changes on chest X-ray and MDCT

    PubMed Central

    2014-01-01

    Background To determine the prevalence of asbestos-related changes on chest X-ray (CXR) and low-dose multidetector-row CT (MDCT) of the thorax in a cohort of formerly asbestos-exposed power industry workers and to assess the importance of common risk factors associated with specific radiological changes. Methods To assess the influence of selected risk factors (age, time since first exposure, exposure duration, cumulative exposure and pack years) on typical asbestos-related radiographic changes, we employed multiple logistic regression and receiver operating characteristic (ROC) analysis. Results On CXR, pleural changes and asbestosis were strongly associated with age, years since first exposure and exposure duration. The MDCT results showed an association between asbestosis and age and between plaques and exposure duration, years since first exposure and cumulative exposure. Parenchymal changes on CXR and MDCT, and diffuse pleural thickening on CXR were both associated with smoking. Using a cut-off of 55 years for age, 17 years for exposure duration and 28 years for latency, benign radiological changes in the cohort with CXR could be predicted with a sensitivity of 82.0% for all of the three variables and a specificity of 47.4%, 39.0% and 40.6%, respectively. Conclusions Participants aged 55 years and older and those with an asbestos exposure of at least 17 years or 28 years since first exposure should be seen as having an increased risk of abnormal radiological findings. For implementing a more focused approach the routine use of low-dose MDCT rather than CXR at least for initial examinations would be justified. PMID:24808921

  8. Comparing Hyperion Lunar Observation with model calculations in support of GOES-R Advanced Baseline Imager (ABI) calibration

    NASA Astrophysics Data System (ADS)

    Shao, Xi; Cao, Changyong; Uprety, Sirish; Padula, Frank; Choi, Taeyoung

    2014-09-01

    Radiometric stability of the lunar surface and its smooth reflectance spectrum makes the moon an attractive candidate for calibrating satellite-based hyper/multi-band visible and infrared imagers. Long-term performance monitoring of satellite instrument using Moon can reveal the degradation of instruments. In this paper, analysis of Hyperion lunar observations and comparison with lunar model are performed in support of Cal/Val activities for satellite photometric imager such as GOES-R Advanced Baseline Imager (ABI) instrument. Hyperion makes hyper-spectral observations of the moon regularly with moon phase mostly at 7 degree and it covers visible and shirt-wavelength infrared (SWIR) channels with 10 nm spectral resolution. Five Hyperion lunar observations are analyzed. Lunar reflectance is derived from Hyperion observation and the mean absolute lunar spectral reflectance difference between Hyperion derivation and lunar model is 4.0 ± 2.62%. Through reflectance comparison, over-compensation of two strong atmospheric water absorption bands in Hyperion calibration is identified. The radiometric variance and degradation of Hyperion are assessed. To support the calibration of GOES-R ABI, hyper-spectral data of Hyperion lunar observation is convoluted with ABI spectral response functions for reflective solar bands to synthesize predicted lunar images to be observed by ABI. Lunar irradiances are derived from these synthesized lunar images for ABI and compared with lunar model predictions to quantify spectral biases. Long-term lunar imaging window of opportunities for GOES-R ABI are also assessed. The ability of using lunar model and Hyperion observation to calibrate satellite VNIR/SWIR sensors and reduce the measurement uncertainties is essential to support post-launch Cal/Val activities of GOES-R ABI.

  9. Simulation study comparing exposure matching with regression adjustment in an observational safety setting with group sequential monitoring.

    PubMed

    Stratton, Kelly G; Cook, Andrea J; Jackson, Lisa A; Nelson, Jennifer C

    2015-03-30

    Sequential methods are well established for randomized clinical trials (RCTs), and their use in observational settings has increased with the development of national vaccine and drug safety surveillance systems that monitor large healthcare databases. Observational safety monitoring requires that sequential testing methods be better equipped to incorporate confounder adjustment and accommodate rare adverse events. New methods designed specifically for observational surveillance include a group sequential likelihood ratio test that uses exposure matching and generalized estimating equations approach that involves regression adjustment. However, little is known about the statistical performance of these methods or how they compare to RCT methods in both observational and rare outcome settings. We conducted a simulation study to determine the type I error, power and time-to-surveillance-end of group sequential likelihood ratio test, generalized estimating equations and RCT methods that construct group sequential Lan-DeMets boundaries using data from a matched (group sequential Lan-DeMets-matching) or unmatched regression (group sequential Lan-DeMets-regression) setting. We also compared the methods using data from a multisite vaccine safety study. All methods had acceptable type I error, but regression methods were more powerful, faster at detecting true safety signals and less prone to implementation difficulties with rare events than exposure matching methods. Method performance also depended on the distribution of information and extent of confounding by site. Our results suggest that choice of sequential method, especially the confounder control strategy, is critical in rare event observational settings. These findings provide guidance for choosing methods in this context and, in particular, suggest caution when conducting exposure matching.

  10. Wind-Wave Effects on Vertical Mixing in Chesapeake Bay, USA: comparing observations to second-moment closure predictions.

    NASA Astrophysics Data System (ADS)

    Fisher, A. W.; Sanford, L. P.; Scully, M. E.

    2016-12-01

    Coherent wave-driven turbulence generated through wave breaking or nonlinear wave-current interactions, e.g. Langmuir turbulence (LT), can significantly enhance the downward transfer of momentum, kinetic energy, and dissolved gases in the oceanic surface layer. There are few observations of these processes in the estuarine or coastal environments, where wind-driven mixing may co-occur with energetic tidal mixing and strong density stratification. This presents a major challenge for evaluating vertical mixing parameterizations used in modeling estuarine and coastal dynamics. We carried out a large, multi-investigator study of wind-driven estuarine dynamics in the middle reaches of Chesapeake Bay, USA, during 2012-2013. The center of the observational array was an instrumented turbulence tower with both atmospheric and marine turbulence sensors as well as rapidly sampled temperature and conductivity sensors. For this paper, we examined the impacts of surface gravity waves on vertical profiles of turbulent mixing and compared our results to second-moment turbulence closure predictions. Wave and turbulence measurements collected from the vertical array of Acoustic Doppler Velocimeters (ADVs) provided direct estimates of the dominant terms in the TKE budget and the surface wave field. Observed dissipation rates, TKE levels, and turbulent length scales are compared to published scaling relations and used in the calculation of second-moment nonequilibrium stability functions. Results indicate that in the surface layer of the estuary, where elevated dissipation is balanced by vertical divergence in TKE flux, existing nonequilibrium stability functions underpredict observed eddy viscosities. The influences of wave breaking and coherent wave-driven turbulence on modeled and observed stability functions will be discussed further in the context of turbulent length scales, TKE and dissipation profiles, and the depth at which the wave-dominated turbulent transport layer

  11. Comparison of Airglow from excited O2- and OH-molecules in the global model EMAC compared to SCIAMACHY observations

    NASA Astrophysics Data System (ADS)

    Versick, Stefan; Bender, Stefan; von Savigny, Christian; Sinnhuber, Miriam; Teiser, Georg; Vlasov, Alexey; Zarboo, Amirmahdi

    2016-04-01

    Airglow is a luminous effect mainly in the upper atmosphere (mesosphere and thermosphere). It is caused by various processes. Airglow can be used to derive minor species abundances, to diagnose dynamical phenomena or to derive chemical heating rates (Mlynzcak 1999). Here we concentrate on Airglow from excited O2- and OH-molecules. For the presented study we use the newly developed extended EMAC (3d-CTM) version which includes the thermosphere and reaches upto about 170 km. We extended the chemistry by the relevant processes for airglow. The online-coupled chemistry module MECCA is calculating the different transitions of the excited OH-molecules. In this presentation we weill concentrate on the OH(3-1) transition at a wavelength of 1540 nm. We compare the model results to SCIAMACHY observations during the sudden stratospheric warming in the northern hemisphere winter 2008/09. The model results are qualitatively in good agreement with the observations. EMAC chemistry has also been extended by two excited states of molcular oxygen: O2(1Δ) at 1270 nm and O2(1Σ) at 762 nm. We show first results of the newly developed retrieval for the 762 nm band from SCIAMACHY-observations and compare it to EMAC results.

  12. Meta-analyses of Adverse Effects Data Derived from Randomised Controlled Trials as Compared to Observational Studies: Methodological Overview

    PubMed Central

    Golder, Su; Loke, Yoon K.; Bland, Martin

    2011-01-01

    Background There is considerable debate as to the relative merits of using randomised controlled trial (RCT) data as opposed to observational data in systematic reviews of adverse effects. This meta-analysis of meta-analyses aimed to assess the level of agreement or disagreement in the estimates of harm derived from meta-analysis of RCTs as compared to meta-analysis of observational studies. Methods and Findings Searches were carried out in ten databases in addition to reference checking, contacting experts, citation searches, and hand-searching key journals, conference proceedings, and Web sites. Studies were included where a pooled relative measure of an adverse effect (odds ratio or risk ratio) from RCTs could be directly compared, using the ratio of odds ratios, with the pooled estimate for the same adverse effect arising from observational studies. Nineteen studies, yielding 58 meta-analyses, were identified for inclusion. The pooled ratio of odds ratios of RCTs compared to observational studies was estimated to be 1.03 (95% confidence interval 0.93–1.15). There was less discrepancy with larger studies. The symmetric funnel plot suggests that there is no consistent difference between risk estimates from meta-analysis of RCT data and those from meta-analysis of observational studies. In almost all instances, the estimates of harm from meta-analyses of the different study designs had 95% confidence intervals that overlapped (54/58, 93%). In terms of statistical significance, in nearly two-thirds (37/58, 64%), the results agreed (both studies showing a significant increase or significant decrease or both showing no significant difference). In only one meta-analysis about one adverse effect was there opposing statistical significance. Conclusions Empirical evidence from this overview indicates that there is no difference on average in the risk estimate of adverse effects of an intervention derived from meta-analyses of RCTs and meta-analyses of observational

  13. Characterization of atypical cystic renal masses with MDCT: comparison of 5-mm axial images and thin multiplanar reconstructed images.

    PubMed

    Bertolotto, Michele; Zappetti, Roberta; Cavallaro, Marco; Perrone, Rosaria; Perretti, Leonardo; Cova, Maria Assunta

    2010-09-01

    The purpose of this study was to investigate whether cystic renal masses are better characterized on thin axial and multiplanar reconstructed MDCT images than on 5-mm images. The records of 70 complex cystic renal masses in 59 patients (45 men, 14 women; mean age, 68 +/- 13 years) who underwent 64-MDCT at two medical centers were studied. Twenty-three of the masses were confirmed on the basis of the histologic findings and 47 in 2-4 years of follow-up. Images were reviewed in two sessions by two radiologists with 12 and 2 years of experience. In the first session, 5-mm axial images were analyzed, and in the second, thin axial images and multiplanar reconstructions. To assess intraobserver variability, analysis was repeated after 1 month. Statistical analysis was performed with Wilcoxon's signed rank test, receiver operating characteristic analysis, and weighted kappa statistics. Radiologists 1 and 2 detected thicker cystic walls (p < 0.001, p < 0.005) and septa (p < 0.03, p < 0.05) and fewer septa (p < 0.005, p < 0.002) on 5-mm axial images and assigned significantly different Bosniak categories than they did in analysis of the volume data (p < 0.04, p < 0.05). Variability was reduced in thin axial and multiplanar views. No significant differences were found in characterization of lesions as benign or malignant in review of 5-mm axial images and volume data sets. The areas under the receiver operating characteristic curve were 0.89 for 5-mm images and 0.96 for volume data sets for radiologist 1 and 0.87 and 0.90 for radiologist 2. Analysis of volume data sets is associated with less intraobserver and interobserver variability than review of 5-mm axial images. Wall thickness and the number and thickness of septa may differ, resulting in assignment of different Bosniak categories. Diagnostic performance in characterizing lesions as benign or malignant, however, is not statistically different for the thick and thin images.

  14. Systems for Lung Volume Standardization during Static and Dynamic MDCT-based Quantitative Assessment of Pulmonary Structure and Function

    PubMed Central

    Fuld, Matthew K.; Grout, Randall; Guo, Junfeng; Morgan, John H.; Hoffman, Eric A.

    2013-01-01

    Rationale and Objectives Multidetector-row Computed Tomography (MDCT) has emerged as a tool for quantitative assessment of parenchymal destruction, air trapping (density metrics) and airway remodeling (metrics relating airway wall and lumen geometry) in chronic obstructive pulmonary disease (COPD) and asthma. Critical to the accuracy and interpretability of these MDCT-derived metrics is the assurance that the lungs are scanned during a breath-hold at a standardized volume. Materials and Methods A computer monitored turbine-based flow meter system was developed to control patient breath-holds and facilitate static imaging at fixed percentages of the vital capacity. Due to calibration challenges with gas density changes during multi-breath xenon-CT an alternative system was required. The design incorporated dual rolling seal pistons. Both systems were tested in a laboratory environment and human subject trials. Results The turbine-based system successfully controlled lung volumes in 32/37 subjects, having a linear relationship for CT measured air volume between repeated scans: for all scans, the mean and confidence interval of the differences (scan1-scan2) was −9 ml (−169, 151); for TLC alone 6 ml (−164, 177); for FRC alone, −23 ml (−172, 126). The dual-piston system successfully controlled lung volume in 31/41 subjects. Study failures related largely to subject non-compliance with verbal instruction and gas leaks around the mouthpiece. Conclusion We demonstrate the successful use of a turbine-based system for static lung volume control and demonstrate its inadequacies for dynamic xenon-CT studies. Implementation of a dual-rolling seal spirometer has been shown to adequately control lung volume for multi-breath wash-in xenon-CT studies. These systems coupled with proper patient coaching provide the tools for the use of CT to quantitate regional lung structure and function. The wash-in xenon-CT method for assessing regional lung function, while not

  15. Observational study designs for comparative effectiveness research: an alternative approach to close evidence gaps in head-and-neck cancer.

    PubMed

    Goulart, Bernardo H L; Ramsey, Scott D; Parvathaneni, Upendra

    2014-01-01

    Comparative effectiveness research (CER) has emerged as an approach to improve quality of care and patient outcomes while reducing healthcare costs by providing evidence to guide healthcare decisions. Randomized controlled trials (RCTs) have represented the ideal study design to support treatment decisions in head-and-neck (H&N) cancers. In RCTs, formal chance (randomization) determines treatment allocation, which prevents selection bias from distorting the measure of treatment effects. Despite this advantage, only a minority of patients qualify for inclusion in H&N RCTs, which limits the validity of their results to the broader H&N cancer patient population seen in clinical practice. Randomized controlled trials often do not address other knowledge gaps in the management of H&N cancer, including treatment comparisons for rare types of H&N cancers, monitoring of rare or late toxicity events (eg, osteoradionecrosis), or in some instances an RCT is simply not feasible. Observational studies, or studies in which treatment allocation occurs independently of investigators' choice or randomization, may address several of these gaps in knowledge, thereby complementing the role of RCTs. This critical review discusses how observational CER studies complement RCTs in generating the evidence to inform healthcare decisions and improve the quality of care and outcomes of H&N cancer patients. Review topics include a balanced discussion about the strengths and limitations of both RCT and observational CER study designs; a brief description of design and analytic techniques to handle selection bias in observational studies; examples of observational studies that inform current clinical practices and management of H&N cancers; and suggestions for relevant CER questions that could be addressed by an observational study design. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Comparing observations of fossil fuel-derived CO2 in California with predictions from bottom-up inventories

    NASA Astrophysics Data System (ADS)

    Graven, H. D.; Lueker, T.; Fischer, M. L.; Guilderson, T. P.; Keeling, R. F.; Brophy, K.; Arnold, T.; Bambha, R.; Callahan, W.; Campbell, J. E.; Frankenberg, C.; Hsu, Y.; Iraci, L. T.; Jeong, S.; Kim, J.; LaFranchi, B. W.; Lehman, S.; Manning, A.; Michelsen, H. A.; Miller, J. B.; Newman, S.; Parazoo, N.; Sloop, C.; Walker, S.; Whelan, M.; Wunch, D.

    2015-12-01

    The US state of California has a progressive climate change mitigation policy, AB-32, enacted in 2006 to reduce greenhouse gas emissions 15% by 2020 and then a further 80% by 2050. Bottom-up inventories indicate California's fossil fuel CO2 emissions are currently about 100 Mt C per year, but different inventories show discrepancies of ±15% in the state-wide total, and some larger discrepancies in various sub-regions of the state. We are developing a top-down framework for investigating fossil fuel and biospheric CO2 fluxes in California using atmospheric observations and models. California has a relatively dense collaborative network of greenhouse gas observations run by several universities, government laboratories and Earth Networks. Using this collaborative network, we conducted three field campaigns in 2014-15 to sample flasks at 10 tower sites across the state. Flasks were analysed for atmospheric CO2 and CO concentrations and for stable isotopes and radiocarbon in CO2. The flask observations of radiocarbon in CO2 allow patterns of fossil fuel-derived and biospheric CO2 to be distinguished at relatively high resolution across the state. We will report initial results from the observations showing regional gradients in fossil fuel-derived CO2 and fluctuations from changing weather patterns. We will compare the observations of fossil fuel-derived CO2 to predictions from several bottom-up inventories and two atmospheric models. Linking the flask data with observations from OCO-2, TCCON, aircraft flights and ground-based in situ analyzers, we will examine the variation in total CO2 and its drivers over California. Further analysis is planned to integrate the data into an inversion framework for fossil fuel and biospheric CO2 fluxes over California.

  17. Observational Study Designs for Comparative Effectiveness Research: An Alternative Approach to Close Evidence Gaps in Head-and-Neck Cancer

    SciTech Connect

    Goulart, Bernardo H.L.; Ramsey, Scott D.; Parvathaneni, Upendra

    2014-01-01

    Comparative effectiveness research (CER) has emerged as an approach to improve quality of care and patient outcomes while reducing healthcare costs by providing evidence to guide healthcare decisions. Randomized controlled trials (RCTs) have represented the ideal study design to support treatment decisions in head-and-neck (H and N) cancers. In RCTs, formal chance (randomization) determines treatment allocation, which prevents selection bias from distorting the measure of treatment effects. Despite this advantage, only a minority of patients qualify for inclusion in H and N RCTs, which limits the validity of their results to the broader H and N cancer patient population seen in clinical practice. Randomized controlled trials often do not address other knowledge gaps in the management of H and N cancer, including treatment comparisons for rare types of H and N cancers, monitoring of rare or late toxicity events (eg, osteoradionecrosis), or in some instances an RCT is simply not feasible. Observational studies, or studies in which treatment allocation occurs independently of investigators' choice or randomization, may address several of these gaps in knowledge, thereby complementing the role of RCTs. This critical review discusses how observational CER studies complement RCTs in generating the evidence to inform healthcare decisions and improve the quality of care and outcomes of H and N cancer patients. Review topics include a balanced discussion about the strengths and limitations of both RCT and observational CER study designs; a brief description of design and analytic techniques to handle selection bias in observational studies; examples of observational studies that inform current clinical practices and management of H and N cancers; and suggestions for relevant CER questions that could be addressed by an observational study design.

  18. The Effect of Workers' Compensation Status on Outcomes of Cervical Disc Arthroplasty: A Prospective, Comparative, Observational Study.

    PubMed

    Gornet, Matthew F; Schranck, Francine W; Copay, Anne G; Kopjar, Branko

    2016-01-20

    Receiving Workers' Compensation benefits has been associated with inferior outcomes after lumbar fusion. The purpose of our study was to compare the outcomes of cervical disc arthroplasty between patients receiving and those not receiving Workers' Compensation. Patient-reported outcomes, reoperations, complications, and return-to-work status were analyzed at one year after surgery in an observational cohort of consecutive patients who underwent single-level or multilevel cervical disc arthroplasty for symptomatic cervical disc conditions, including radiculopathy or discogenic pain with or without radiculopathy, exclusive of myelopathy. Of the 189 patients who underwent cervical disc arthroplasty, 144 received Workers' Compensation and forty-five did not. The mean scores on all patient-reported measures improved significantly from preoperative baseline to one year after surgery (p < 0.001), and the improvement in patient-reported outcomes did not differ significantly between the Workers' Compensation and the non-Workers' Compensation group (respectively, 22.7 compared with 25.0 for the Neck Disability Index; 8.3 compared with 9.6 for the Short Form (SF)-36 physical component summary; 7.9 compared with 9.6 for the SF-36 mental component summary; 3.5 compared with 3.7 for neck pain; and 2.6 compared with 2.8 for arm pain). The two groups also did not differ significantly in the rate of reoperations (7.6% for those receiving Workers' Compensation compared with 13.3% for those not receiving Workers' Compensation) and complications (2.8% compared with 4.4%, respectively). At one year after surgery, the proportion of patients who had returned to work was comparable (77.7% in the Workers' Compensation group and 79.4% in the non-Workers' Compensation group); however, the patients receiving Workers' Compensation had significantly more days off before returning to work (a mean of 145.2 compared with 61.9 days; p = 0.001). After cervical disc arthroplasty, patients receiving

  19. A comparative analysis of simulated and observed landslide locations triggered by Hurricane Camille in Nelson County, Virginia

    USGS Publications Warehouse

    Morrissey, M.M.; Wieczorek, G.F.; Morgan, B.A.

    2008-01-01

    In 1969, Nelson County, Virginia received up to 71 cm of rain within 12 h starting at 7 p.m. on August 19. The total rainfall from the storm exceeded the 1000-year return period in the region. Several thousands of landslides were induced by rainfall associated with Hurricane Camille causing fatalities and destroying infrastructure. We apply a distributed transient response model for regional slope stability analysis to shallow landslides. Initiation points of over 3000 debris flows and effects of flooding from this storm are applied to the model. Geotechnical data used in the calculations are published data from samples of colluvium. Results from these calculations are compared with field observations such as landslide trigger location and timing of debris flows to assess how well the model predicts the spatial and temporal distribution. of landslide initiation locations. The model predicts many of the initiation locations in areas where debris flows are observed. Copyright ?? 2007 John Wiley & Sons, Ltd.

  20. Comparative analysis of different sensor data (Landsat-TM and MOMS) for earth observation and impact on future sensor development

    NASA Technical Reports Server (NTRS)

    Bodechtel, J.; Zilger, J.; Salomonson, V. V.

    1986-01-01

    The missions of the German Modular Optoelectronic Multispectral Scanner (MOMS) aboard two STS flights demonstrated the feasibility of a novel concept with regard to both technical and scientific objectives. On account of the successful missions, a cooperation was agreed between the German Federal Minister for Research nad Technology and NASA for comparing MOMS observations with the more familiar operational Landsat-TM data over selected test sites, as a means of obtaining some relative measure of performance. This paper summarizes the results obtained and presents the MOMS-02, a further experimental representative of the MOMS program aiming at the realization of an operational system for the mid-nineties.

  1. Comparative analysis of different sensor data (Landsat-TM and MOMS) for earth observation and impact on future sensor development

    NASA Technical Reports Server (NTRS)

    Bodechtel, J.; Zilger, J.; Salomonson, V. V.

    1986-01-01

    The missions of the German Modular Optoelectronic Multispectral Scanner (MOMS) aboard two STS flights demonstrated the feasibility of a novel concept with regard to both technical and scientific objectives. On account of the successful missions, a cooperation was agreed between the German Federal Minister for Research nad Technology and NASA for comparing MOMS observations with the more familiar operational Landsat-TM data over selected test sites, as a means of obtaining some relative measure of performance. This paper summarizes the results obtained and presents the MOMS-02, a further experimental representative of the MOMS program aiming at the realization of an operational system for the mid-nineties.

  2. A new method to compare hourly rainfall between station observations and satellite products over central-eastern China

    NASA Astrophysics Data System (ADS)

    Chen, Haoming; Yu, Rucong; Shen, Yan

    2016-08-01

    This study employs a newly defined regional-rainfall-event (RRE) concept to compare the hourly characteristics of warm-season (May-September) rainfall among rain gauge observations, China merged hourly precipitation analysis (CMPA-Hourly), and two commonly used satellite products (TRMM 3B42 and CMORPH). By considering the rainfall characteristics in a given limited area rather than a single point or grid, this method largely eliminates the differences in rainfall characteristics among different observations or measurements over central-eastern China. The results show that the spatial distribution and diurnal variation of RRE frequency and intensity are quite consistent among different datasets, and the performance of CMPA-Hourly is better than the satellite products when compared with station observations. A regional rainfall coefficient (RRC), which can be used to classify local rain and regional rain, is employed to represent the spatial spread of rainfall in the limited region defining the RRE. It is found that rainfall spread in the selected grid box is more uniform during the nocturnal to morning hours over central-eastern China. The RRC tends to reach its diurnal maximum several hours after the RRE intensity peaks, implying an intermediate transition stage from convective to stratiform rainfall. In the afternoon, the RRC reaches its minimum, implying the dominance of local convections on small spatial scale in those hours, which could cause large differences in rain gauge and satellite observations. Since the RRE method reflects the overall features of rainfall in a limited region rather than at a fixed point or in a single grid, the widely recognized overestimation of afternoon rainfall in satellite products is not obvious, and thus the satellite estimates are more reliable in representing sub-daily variation of rainfall from the RRE perspective. This study proposes a reasonable method to compare satellite products with rain gauge observations on the sub

  3. RTOG 9804: A Prospective Randomized Trial for Good-Risk Ductal Carcinoma In Situ Comparing Radiotherapy With Observation

    PubMed Central

    McCormick, Beryl; Winter, Kathryn; Hudis, Clifford; Kuerer, Henry Mark; Rakovitch, Eileen; Smith, Barbara L.; Sneige, Nour; Moughan, Jennifer; Shah, Amit; Germain, Isabelle; Hartford, Alan C.; Rashtian, Afshin; Walker, Eleanor M.; Yuen, Albert; Strom, Eric A.; Wilcox, Jeannette L.; Vallow, Laura A.; Small, William; Pu, Anthony T.; Kerlin, Kevin; White, Julia

    2015-01-01

    Purpose The Radiation Therapy Oncology Group 9804 study identified good-risk patients with ductal carcinoma in situ (DCIS), a breast cancer diagnosis found frequently in mammographically detected cancers, to test the benefit of radiotherapy (RT) after breast-conserving surgery compared with observation. Patients and Methods This prospective randomized trial (1998 to 2006) in women with mammographically detected low- or intermediate-grade DCIS, measuring less than 2.5 cm with margins ≥ 3 mm, compared RT with observation after surgery. The study was designed for 1,790 patients but was closed early because of lower than projected accrual. Six hundred thirty-six patients from the United States and Canada were entered; tamoxifen use (62%) was optional. Ipsilateral local failure (LF) was the primary end point; LF and contralateral failure were estimated using cumulative incidence, and overall and disease-free survival were estimated using the Kaplan-Meier method. Results Median follow-up time was 7.17 years (range, 0.01 to 11.33 years). Two LFs occurred in the RT arm, and 19 occurred in the observation arm. At 7 years, the LF rate was 0.9% (95% CI, 0.0% to 2.2%) in the RT arm versus 6.7% (95% CI, 3.2% to 9.6%) in the observation arm (hazard ratio, 0.11; 95% CI, 0.03 to 0.47; P < .001). Grade 1 to 2 acute toxicities occurred in 30% and 76% of patients in the observation and RT arms, respectively; grade 3 or 4 toxicities occurred in 4.0% and 4.2% of patients, respectively. Late RT toxicity was grade 1 in 30%, grade 2 in 4.6%, and grade 3 in 0.7% of patients. Conclusion In this good-risk subset of patients with DCIS, with a median follow-up of 7 years, the LF rate was low with observation but was decreased significantly with the addition of RT. Longer follow-up is planned because the timeline for LF in this setting seems protracted. PMID:25605856

  4. A Study of The Eastern Mediterranean Hydrology and Circulation By Comparing Observation and High Resolution Numerical Model Results.

    NASA Astrophysics Data System (ADS)

    Alhammoud, B.; Béranger, K.; Mortier, L.; Crépon, M.

    The Eastern Mediterranean hydrology and circulation are studied by comparing the results of a high resolution primitive equation model (described in dedicated session: Béranger et al.) with observations. The model has a horizontal grid mesh of 1/16o and 43 z-levels in the vertical. The model was initialized with the MODB5 climatology and has been forced during 11 years by the daily sea surface fluxes provided by the European Centre for Medium-range Weather Forecasts analysis in a perpetual year mode corresponding to the year March 1998-February 1999. At the end of the run, the numerical model is able to accurately reproduce the major water masses of the Eastern Mediterranean Basin (Levantine Surface Water, modi- fied Atlantic Water, Levantine Intermediate Water, and Eastern Mediterranean Deep Water). Comparisons with the POEM observations reveal good agreement. While the initial conditions of the model are somewhat different from POEM observations, dur- ing the last year of the simulation, we found that the water mass stratification matches that of the observations quite well in the seasonal mean. During the 11 years of simulation, the model drifts slightly in the layers below the thermocline. Nevertheless, many important physical processes were reproduced. One example is that the dispersal of Adriatic Deep Water into the Levantine Basin is rep- resented. In addition, convective activity located in the northern part of the Levantine Basin occurs in Spring as expected. The surface circulation is in agreement with in-situ and satellite observations. Some well known mesoscale features of the upper thermocline circulation are shown. Sea- sonal variability of transports through Sicily, Otranto and Cretan straits are inves- tigated as well. This work was supported by the french MERCATOR project and SHOM.

  5. Characteristic image quality of a third generation dual-source MDCT scanner: Noise, resolution, and detectability

    SciTech Connect

    Solomon, Justin; Wilson, Joshua; Samei, Ehsan

    2015-08-15

    Purpose: The purpose of this work was to assess the inherent image quality characteristics of a new multidetector computed tomography system in terms of noise, resolution, and detectability index as a function of image acquisition and reconstruction for a range of clinically relevant settings. Methods: A multisized image quality phantom (37, 30, 23, 18.5, and 12 cm physical diameter) was imaged on a SOMATOM Force scanner (Siemens Medical Solutions) under variable dose, kVp, and tube current modulation settings. Images were reconstructed with filtered back projection (FBP) and with advanced modeled iterative reconstruction (ADMIRE) with iterative strengths of 3, 4, and 5. Image quality was assessed in terms of the noise power spectrum (NPS), task transfer function (TTF), and detectability index for a range of detection tasks (contrasts of approximately 45, 90, 300, −900, and 1000 HU, and 2–20 mm diameter) based on a non-prewhitening matched filter model observer with eye filter. Results: Image noise magnitude decreased with decreasing phantom size, increasing dose, and increasing ADMIRE strength, offering up to 64% noise reduction relative to FBP. Noise texture in terms of the NPS was similar between FBP and ADMIRE (<5% shift in peak frequency). The resolution, based on the TTF, improved with increased ADMIRE strength by an average of 15% in the TTF 50% frequency for ADMIRE-5. The detectability index increased with increasing dose and ADMIRE strength by an average of 55%, 90%, and 163% for ADMIRE 3, 4, and 5, respectively. Assessing the impact of mA modulation for a fixed average dose over the length of the phantom, detectability was up to 49% lower in smaller phantom sections and up to 26% higher in larger phantom sections for the modulated scan compared to a fixed tube current scan. Overall, the detectability exhibited less variability with phantom size for modulated scans compared to fixed tube current scans. Conclusions: Image quality increased with

  6. Comparative analysis of atmosphere temperature variability for Northern Eurasia based on the Reanalysis and in-situ observed data

    NASA Astrophysics Data System (ADS)

    Shulgina, T.; Genina, E.; Gordov, E.; Nikitchuk, K.

    2009-04-01

    At present numerous data archives which include meteorological observations as well as climate processes modeling data are available for Earth Science specialists. Methods of mathematical statistics are widely used for their processing and analysis. In many cases they represent the only way of quantitative assessment of the meteorological and climatic information. Unified set of analysis methods allows us to compare climatic characteristics calculated on the basis of different datasets with the purpose of performing more detailed analysis of climate dynamics for both regional and global levels. The report presents the results of comparative analysis of atmosphere temperature behavior for the Northern Eurasia territory for the period from 1979 to 2004 based on the NCEP/NCAR Reanalysis, NCEP/DOE Reanalysis AMIP II, JMA/CRIEPI JRA-25 Reanalysis, ECMWF ERA-40 Reanalysis data and observation data obtained from meteorological stations of the former Soviet Union. Statistical processing of atmosphere temperature data included analysis of time series homogeneity of climate indices approved by WMO, such as "Number of frost days", "Number of summer days", "Number of icing days", "Number of tropical nights", etc. by means of parametric methods of mathematical statistics (Fisher and Student tests). That allowed conducting comprehensive research of spatio-temporal features of the atmosphere temperature. Analysis of the atmosphere temperature dynamics revealed inhomogeneity of the data obtained for large observation intervals. Particularly, analysis performed for the period 1979 - 2004 showed the significant increase of the number of frost and icing days approximately by 1 day for every 2 years and decrease roughly by 1 day for 2 years for the number of summer days. Also it should be mentioned that the growth period mean temperature have increased by 1.5 - 2° C for the time period being considered. The usage of different Reanalysis datasets in conjunction with in-situ observed

  7. Living with dementia in hospital wards: a comparative study of staff perceptions of practice and observed patient experience.

    PubMed

    Innes, Anthea; Kelly, Fiona; Scerri, Charles; Abela, Stephen

    2016-06-01

    To ascertain the experiences, attitudes and knowledge of staff working in two Maltese hospital wards and the observed experiences of people with dementia living there. To examine the impact of recommendations made in October 2011 for improving the psychosocial and physical environments of the wards 1 year later. There is an increasing policy recognition of the need for a better trained and educated dementia care workforce and of ensuring that the environmental design of care settings meets the needs of people with dementia. At both time points, three established and validated data-collection methods evaluated (i) staff/patient interaction and patient experience, (ii) the extent to which the wards met dementia friendly principles and (iii) staff views about their work environment and their perceptions about their practice. Sixteen (five male and 11 female) patients with dementia and 69 staff in the two wards participated in the study. We noted small but important changes; however, the physical and psychosocial environments of the wards did not always align to current recommendations for dementia care, with staff perceptions of care delivery not always reflecting the observed experiences of care of those living with dementia. Comparing staff questionnaire data with observational methods offered a unique opportunity to understand multiple perspectives in a complex hospital setting. Incorporating these perspectives into staff and management feedback allowed for recommendations that recognised both patient-centred values and staff constraints. © 2016 John Wiley & Sons Ltd.

  8. Treatment of female stress urinary incontinence using suburethral slings: comparative, retrospective, observational study of two surgical techniques.

    PubMed

    Castroviejo-Royo, F; Martinez-Sagarra-Oceja, J M; Marina-García-Tuñón, C; Conde-Redondo, C; Rodríguez-Toves, L A; González-Tejero, C

    2013-10-01

    The treatment of female stress urinary incontinence has undergone a revolution in recent years due the emergence on the market of suburethral slings. The aim of this study is to compare two surgical techniques for treating stress urinary incontinence: Monarc™ (transobturator suburethral sling) and MiniArc(®) (single-incision suburethral mini-sling). Comparative, retrospective, observational study from January 2005 to December 2011 on 317 women diagnosed with stress urinary incontinence. Of these, 214 were treated with the Monarc™ transobturator suburethral sling, and 103 were treated with the MiniArc(®) mini-sling. The results were treated with SPSS v.15 software, and the statistical significance was P≤.005. The two patients groups were homogeneous in terms of age, number of births, presence of urgency urinary incontinence and prior hysterectomy. There were significant differences in hospital stay, surgical time and early complications in favour of the MiniArc(®), technique, but overall there were no significant differences in the late complications. Some 84% of the patients treated with the Monarc™ transobturator sling were cured compared with the 72% of patients in whom we implanted a MiniArc(®), a difference that was statistically significant. We need to perform more high-quality, prospective and randomised studies with larger numbers of patients and longer follow-up times to confirm or disprove the difference that we found in the success rate for the Monarc™ transobturator suburethral sling. Copyright © 2012 AEU. Published by Elsevier Espana. All rights reserved.

  9. Radiation dose in a "triple rule-out" coronary CT angiography protocol of emergency department patients using 64-MDCT: the impact of ECG-based tube current modulation on age, sex, and body mass index.

    PubMed

    Takakuwa, Kevin M; Halpern, Ethan J; Gingold, Eric L; Levin, David C; Shofer, Frances S

    2009-04-01

    "Triple rule-out" coronary CT angiography (CTA) using 64-MDCT technology is a new approach for evaluating emergency department patients presenting with symptoms suggestive of acute coronary syndrome (ACS). Our objective was to evaluate the reduction in effective radiation dose through the use of tube current modulation in patients who underwent a triple rule-out coronary CTA evaluation and to document how effective radiation dose was impacted by patient age, sex, and body mass index (BMI). A retrospective analysis of triple rule-out coronary CTA examinations performed on a 64-MDCT scanner was ordered on a prospective cohort of 267 consecutive low- to moderate-risk emergency department patients with suspected ACS from a single university hospital between October 2006 and March 2008. Tube current modulation was generally used in patients with heart rates below 65 beats per minute during the second half of the study period as a way to reduce radiation exposure. We calculated effective radiation exposure using actual patient coronary CTA scanning parameters by age, sex, and BMI. Among the 172 patients evaluated without tube current modulation, effective dose averaged (+/- SD) 18.0 +/- 5.6 mSv (range, 9.9-31.3 mSv). Of the 95 patients who underwent CTA examination with tube current modulation, effective dose was significantly lower at 8.75 +/- 2.64 mSv (range, 5.4-16.6 mSv; p < 0.0001) and image quality was better (p < 0.0001) as compared with examinations without tube current modulation. There were no significant radiation differences by patient age, but tube current modulation decreased radiation exposure by at least half. Among the studies in which tube current modulation was not used, women received less radiation than men (17.0 vs 19.5 mSv, respectively; p < 0.001). For the studies with tube current modulation, there were no radiation differences by sex. Obese patients received significantly more radiation than overweight and normal-weight patients in the non

  10. Azilsartan compared to ACE inhibitors in anti-hypertensive therapy: one-year outcomes of the observational EARLY registry.

    PubMed

    Gitt, Anselm K; Bramlage, Peter; Potthoff, Sebastian A; Baumgart, Peter; Mahfoud, Felix; Buhck, Hartmut; Ehmen, Martina; Ouarrak, Taoufik; Senges, Jochen; Schmieder, Roland E

    2016-03-08

    Azilsartan medoxomil (AZL-M), has been demonstrated to be more effective than the other sartans currently in use; however, there is insufficient information available comparing it with ACE-inhibitors. Therefore, we aimed to compare the efficacy, safety, and tolerability of AZL-M with that of ACE-inhibitors in a real life clinical setting. The EARLY registry is a prospective, observational, national, multicentre registry with a follow-up period of 12 months. There were two principal objectives: 1) documentation of the achievement of target BP values set according to recent national and international guidelines, and 2) description of the safety profile of AZL-M. A total of 3 849 patients with essential arterial hypertension were recruited from primary care offices in Germany. Patients who initiated monotherapy at baseline comprising either AZL-M or an ACE-inhibitor were included at a ratio of seven to three. Results demonstrated that a blood pressure target of <140/90 mmHg was achieved by a significantly greater proportion of patients in the AZL-M group (61.1 %) compared with the ACE-inhibitor group (56.4 %; p < 0.05; OR, 1.21; 95 % CI, 1.03-1.42), with this finding maintained after adjusting for differences in baseline characteristics. AZL-M appeared to have an equivalent safety profile to the ACE-inhibitors, with a similar incidence of adverse events in the two patient groups (p = 0.73). These data add to the results of previous randomized controlled clinical trials suggesting that, compared with other agents that target the renin-angiotensin system, AZL-M provides statistically significant albeit small improvements in blood pressure control.

  11. Tonsillectomy efficacy in children with PFAPA syndrome is comparable to the standard medical treatment: a long-term observational study.

    PubMed

    Vigo, Giulia; Martini, Giorgia; Zoppi, Silvia; Vittadello, Fabio; Zulian, Francesco

    2014-01-01

    Tonsillectomy has recently been suggested as an effective treatment for PFAPA syndrome but little is known about its long-term efficacy. We compared the clinical features and the long-term outcome of a large cohort of patients with PFAPA syndrome treated with tonsillectomy or with standard medical treatment. We conducted a retrospective study on patients with PFAPA syndrome followed at a tertiary care centre from January 1993 to August 2010. Clinical characteristics and laboratory parameters were evaluated at onset and during the follow-up. Disease outcomes of patients who underwent tonsillectomy and of those treated with medical therapy (NSAIDs, prednisone) were compared. Clinical remission on medication (CRM) was considered the persistence of fever attacks which were well controlled by medical therapy, clinical remission (CR) was defined as the absence of fever attacks, without any treatment, for more than 12 months. 275 patients with PFAPA syndrome, 59.6% males, aged 27.9 months at onset and followed for mean 54.5 months, entered the study. CR was reported in 59.6% of the patients and was significantly less frequent in those with positive family history for PFAPA (46.4% vs. 66.1%, p=0.003). 27/41 patients (65.9%), responded to tonsillectomy and this result was comparable with that observed in those treated with medical therapy (59.1%, p=0.51). Disease duration, age at remission or presence of associated symptoms were not significantly different in both groups. No predictors of tonsillectomy failure were found. In a large cohort of patients with PFAPA syndrome, tonsillectomy efficacy was comparable to the standard medical treatment.

  12. Gravity wave events from mesoscale simulations, compared to polar stratospheric clouds observed from spaceborne lidar over the Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Noel, V.; Pitts, M.

    2012-06-01

    We compare Gravity Waves (GW) and Polar Stratospheric Clouds (PSC) above the Antarctic Peninsula for winters (June to September) between 2006 and 2010. GW activity is inferred from stratospheric temperature and vertical winds from the Weather and Research Forecast mesoscale model (WRF), and documented as a function of time and geography for the studied period. Significant GW activity affects 36% of days and follows the Peninsula orography closely. Volumes of PSC, composed of ice and Nitric Acid Trihydrate (NAT), are retrieved using observations from the spaceborne lidar CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization). They are documented against GW activity as a function of time and longitude. Sixty-three percent of ice PSC are observed during GW events, when the average volume of PSC per profile doubles. Maximum ice PSC volumes are seen directly over the Peninsula (65°W), while maximum NAT PSC volumes appear downstream further East (˜35°W). Effects of GW events on NAT PSC are felt as far East as 40°E. Our results support the importance of gravity waves as a major mechanism driving the evolution of ice PSC in the area, but the effects on NAT PSC are harder to detect. After a GW event ends, volumes of ice PSC get back to their usual levels in less than 24 h, while this process takes more than 48 h for NAT PSC. Daily profiles of H2O and HNO3 mixing ratios, retrieved from MLS observations, are used to derive ice and NAT frost points with altitude and time. Combining these frost points with modeled stratospheric temperatures, the volumes of air able to support ice and NAT crystals are quantified and compared with PSC volumes. Correlation is high for ice crystals, but not for NAT, consistent with their much slower nucleation mechanisms. Observations of ice PSC over the domain are followed by a strong increase (+50-100%) in NAT PSC formation efficiency 2 to 6 h later. This increase is followed by a steep drop (6-10 h later) and a longer period of slow

  13. Reducing Uncertainty in Terrestrial Biosphere Models with Satellite Observations of Atmospheric CO2: Comparing MsTMIP with GOSAT

    NASA Astrophysics Data System (ADS)

    Swetish, J. B.; Huntzinger, D. N.; Schwalm, C. R.; Fisher, J. B.; Liu, J.; Michalak, A. M.; Bowman, K. W.

    2014-12-01

    Global-scale terrestrial biosphere models (TBMs) vary in their underlying driving assumptions, inputs, and parameterizations. As a result, TBM estimates of carbon fluxes and pools vary greatly and the lack of direct observations of land-atmosphere carbon exchange at the same spatio-temporal resolution (e.g., 0.5° x 0.5° degree and sub-daily to monthly) of model estimates makes it difficult to assess TBM performance in terms of their ability to represent the terrestrial carbon cycle. Atmospheric CO2 measurements, however, may be a potentially powerful observational constraint for TBMs because they provide an integrated view of surface sources and sinks of carbon. The Greenhouse Gases Observing Satellite (GOSAT) measures atmospheric CO2 from space at spatio-temporal scales relatively consistent with model estimates. Using TBM estimates from the North American Carbon Program Multi-scale synthesis and Terrestrial Model Intercomparison Project (MsTMIP), together with estimates of fossil fuel emissions and air-sea fluxes, we translate surfaces fluxes into atmospheric CO2 concentrations using the GEOS-Chem atmospheric transport model. The performance of MsTMIP TBMs is evaluated by comparing the dry air column-averaged mole fractions of CO2 (ΧCO2) from transported surface fluxes to observations of ΧCO2 from GOSAT. While MsTMIP ΧCO2 signals are generally consistent with GOSAT ΧCO2 in the southern hemisphere, MsTMIP and GOSAT XCO2 show profound differences in the northern hemisphere (NH). In general, MsTMIP XCO2 tends to be higher than GOSAT XCO2 at northern latitudes, especially in the NH summer and fall. Looking specifically at regions in the NH, we compare each MsTMIP ΧCO2 to GOSAT ΧCO2 in terms of its ability to reproduce the spatial distribution, magnitude and timing of the GOSAT ΧCO2 seasonal cycle. We use the information derived from the comparison to link model performance with how certain processes are represented within the models themselves, thus aiding

  14. Three-dimensional tropospheric water vapor in coupled climate models compared with observations from the AIRS satellite system

    NASA Astrophysics Data System (ADS)

    Pierce, David W.; Barnett, Tim P.; Fetzer, Eric J.; Gleckler, Peter J.

    2006-11-01

    Changes in the distribution of water vapor in response to anthropogenic forcing will be a major factor determining the warming the Earth experiences over the next century, so it is important to validate climate models' distribution of water vapor. In this work the three-dimensional distribution of specific humidity in state-of-the-art climate models is compared to measurements from the AIRS satellite system. We find the majority of models have a pattern of drier than observed conditions (by 10-25%) in the tropics below 800 hPa, but 25-100% too moist conditions between 300 and 600 hPa, especially in the extra-tropics. Analysis of the accuracy and sampling biases of the AIRS measurements suggests that these differences are due to systematic model errors, which might affect the model-estimated range of climate warming anticipated over the next century.

  15. The Distribution of Snow Black Carbon observed in the Arctic and Compared to the GISS-PUCCINI Model

    NASA Technical Reports Server (NTRS)

    Dou, T.; Xiao, C.; Shindell, D. T.; Liu, J.; Eleftheriadis, K.; Ming, J.; Qin, D.

    2012-01-01

    In this study, we evaluate the ability of the latest NASA GISS composition-climate model, GISS-E2- PUCCINI, to simulate the spatial distribution of snow BC (sBC) in the Arctic relative to present-day observations. Radiative forcing due to BC deposition onto Arctic snow and sea ice is also estimated. Two sets of model simulations are analyzed, where meteorology is linearly relaxed towards National Centers for Environmental Prediction (NCEP) and towards NASA Modern Era Reanalysis for Research and Applications (MERRA) reanalyses. Results indicate that the modeled concentrations of sBC are comparable with presentday observations in and around the Arctic Ocean, except for apparent underestimation at a few sites in the Russian Arctic. That said, the model has some biases in its simulated spatial distribution of BC deposition to the Arctic. The simulations from the two model runs are roughly equal, indicating that discrepancies between model and observations come from other sources. Underestimation of biomass burning emissions in Northern Eurasia may be the main cause of the low biases in the Russian Arctic. Comparisons of modeled aerosol BC (aBC) with long-term surface observations at Barrow, Alert, Zeppelin and Nord stations show significant underestimation in winter and spring concentrations in the Arctic (most significant in Alaska), although the simulated seasonality of aBC has been greatly improved relative to earlier model versions. This is consistent with simulated biases in vertical profiles of aBC, with underestimation in the lower and middle troposphere but overestimation in the upper troposphere and lower stratosphere, suggesting that the wet removal processes in the current model may be too weak or that vertical transport is too rapid, although the simulated BC lifetime seems reasonable. The combination of observations and modeling provides a comprehensive distribution of sBC over the Arctic. On the basis of this distribution, we estimate the decrease in snow

  16. Risk of angioedema associated with levetiracetam compared with phenytoin: Findings of the observational health data sciences and informatics research network.

    PubMed

    Duke, Jon D; Ryan, Patrick B; Suchard, Marc A; Hripcsak, George; Jin, Peng; Reich, Christian; Schwalm, Marie-Sophie; Khoma, Yuriy; Wu, Yonghui; Xu, Hua; Shah, Nigam H; Banda, Juan M; J Schuemie, Martijn

    2017-08-01

    Recent adverse event reports have raised the question of increased angioedema risk associated with exposure to levetiracetam. To help address this question, the Observational Health Data Sciences and Informatics research network conducted a retrospective observational new-user cohort study of seizure patients exposed to levetiracetam (n = 276,665) across 10 databases. With phenytoin users (n = 74,682) as a comparator group, propensity score-matching was conducted and hazard ratios computed for angioedema events by per-protocol and intent-to-treat analyses. Angioedema events were rare in both the levetiracetam and phenytoin groups (54 vs. 71 in per-protocol and 248 vs. 435 in intent-to-treat). No significant increase in angioedema risk with levetiracetam was seen in any individual database (hazard ratios ranging from 0.43 to 1.31). Meta-analysis showed a summary hazard ratio of 0.72 (95% confidence interval [CI] 0.39-1.31) and 0.64 (95% CI 0.52-0.79) for the per-protocol and intent-to-treat analyses, respectively. The results suggest that levetiracetam has the same or lower risk for angioedema than phenytoin, which does not currently carry a labeled warning for angioedema. Further studies are warranted to evaluate angioedema risk across all antiepileptic drugs. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

  17. Comparing Herschel dust emission structures, magnetic fields observed by Planck, and dynamics: high-latitude star forming cloud L1642

    NASA Astrophysics Data System (ADS)

    Malinen, Johanna

    2016-01-01

    The nearby high-latitude cloud L1642 is one of only two known very high latitude (|b| > 30 deg) clouds actively forming stars. This cloud is a rare example of star formation in isolated conditions, and can reveal important details of star formation in general, e.g., of the effect of magnetic fields. We compare Herschel dust emission structures and magnetic field orientation revealed by Planck polarization maps in L1642, and also combine these with dynamic information from molecular line observations. The high-resolution Herschel data reveal a complex structure including a dense, compressed central blob with elongated extensions, low density striations, "fishbone" like structures with a spine and perpendicular striations, and a spiraling "tail". The Planck polarization data reveal an ordered magnetic field that pervades the cloud and is aligned with the surrounding low density striations. We show that there is a complex interplay between the cloud structure and large scale magnetic fields revealed by Planck polarization data at 10' resolution. This suggests that the magnetic field is closely linked to the formation and evolution of the cloud. We see a clear transition from aligned to perpendicular structures approximately at a column density of NH = 2x10^21 cm-2. We conclude that Planck polarization data revealing the large scale magnetic field orientation can be very useful even when comparing to the finest structures in higher resolution data, e.g. Herschel at ~18" resolution.

  18. Comparative ELM study between the observation by ECEI and linear/nonlinear simulation in the KSTAR plasmas

    NASA Astrophysics Data System (ADS)

    Kim, Minwoo; Park, Hyeon K.; Yun, Gunsu; Lee, Jaehyun; Lee, Jieun; Lee, Woochang; Jardin, Stephen; Xu, X. Q.; Kstar Team

    2015-11-01

    The modeling of the Edge-localized-mode (ELM) should be rigorously pursued for reliable and robust ELM control for steady-state long-pulse H-mode operation in ITER as well as DEMO. In the KSTAR discharge #7328, a linear stability of the ELMs is investigated using M3D-C1 and BOUT + + codes. This is achieved by linear simulation for the n = 8 mode structure of the ELM observed by the KSTAR electron cyclotron emission imaging (ECEI) systems. In the process of analysis, variations due to the plasma equilibrium profiles and transport coefficients on the ELM growth rate are investigated and simulation results with the two codes are compared. The numerical simulations are extended to nonlinear phase of the ELM dynamics, which includes saturation and crash of the modes. Preliminary results of the nonlinear simulations are compared with the measured images especially from the saturation to the crash. This work is supported by NRF of Korea under contract no. NRF-2014M1A7A1A03029865, US DoE by LLNL under contract DE-AC52-07NA27344 and US DoE by PPPL under contract DE-AC02-09CH11466.

  19. Retrospective observational study comparing the international hip dysplasia institute classification with the Tonnis classification of developmental dysplasia of the hip.

    PubMed

    Miao, Mingyuan; Cai, Haiqing; Hu, Liwei; Wang, Zhigang

    2017-01-01

    The Tonnis radiographic classification of developmental dysplasia of the hip (DDH) has been widely used. The International Hip Dysplasia Institute (IHDI) classification, a new classification system recently developed by the IHDI, is beginning to be applied to evaluate DDH with the absence of an ossification center. This study aimed to validate its reliability in evaluating DDH with an ossification center and compared the 2 classifications in evaluating all DDH hips. In addition, the prediction values of the 2 classifications on clinical management selection were compared.In total, the pelvic radiographs of 212 DDH patients (318 hips) between the ages of 6 and 48 months admitted to Shanghai Children's Medical Center between 2007 and 2014 were assessed by 3 observers retrospectively using the 2 classifications. Intraobserver and interobserver agreements were evaluated using the kappa method. We also assessed the correlation of the 2 radiographic classifications in terms of treatment selection.In total, 216 hips received closed reduction, 61 hips received open reduction, and 41 hips received pelvic osteotomy. Both classifications showed excellent intraobserver and interobserver reliability. However, the IHDI demonstrated more interobserver reliability, especially for evaluating DDH without an ossification center. Both classifications were found to be relevant in detecting the DDH treatment type (P < 0.01). The Tonnis classification was also relevant, especially for evaluating DDH with an ossification center.The IHDI classification exhibited good practicability in classifying the radiographic severity of DDH compared to the Tonnis classification, particularly in hips without an ossification center. Like the Tonnis classification, the IHDI classification can predict treatment plans. Therefore, the IHDI classification seems to be the upgraded version of the Tonnis classification.

  20. Retrospective observational study comparing the international hip dysplasia institute classification with the Tonnis classification of developmental dysplasia of the hip

    PubMed Central

    Miao, Mingyuan; Cai, Haiqing; Hu, Liwei; Wang, Zhigang

    2017-01-01

    Abstract The Tonnis radiographic classification of developmental dysplasia of the hip (DDH) has been widely used. The International Hip Dysplasia Institute (IHDI) classification, a new classification system recently developed by the IHDI, is beginning to be applied to evaluate DDH with the absence of an ossification center. This study aimed to validate its reliability in evaluating DDH with an ossification center and compared the 2 classifications in evaluating all DDH hips. In addition, the prediction values of the 2 classifications on clinical management selection were compared. In total, the pelvic radiographs of 212 DDH patients (318 hips) between the ages of 6 and 48 months admitted to Shanghai Children's Medical Center between 2007 and 2014 were assessed by 3 observers retrospectively using the 2 classifications. Intraobserver and interobserver agreements were evaluated using the kappa method. We also assessed the correlation of the 2 radiographic classifications in terms of treatment selection. In total, 216 hips received closed reduction, 61 hips received open reduction, and 41 hips received pelvic osteotomy. Both classifications showed excellent intraobserver and interobserver reliability. However, the IHDI demonstrated more interobserver reliability, especially for evaluating DDH without an ossification center. Both classifications were found to be relevant in detecting the DDH treatment type (P < 0.01). The Tonnis classification was also relevant, especially for evaluating DDH with an ossification center. The IHDI classification exhibited good practicability in classifying the radiographic severity of DDH compared to the Tonnis classification, particularly in hips without an ossification center. Like the Tonnis classification, the IHDI classification can predict treatment plans. Therefore, the IHDI classification seems to be the upgraded version of the Tonnis classification. PMID:28099350

  1. Effectiveness of duloxetine compared with pregabalin and gabapentin in diabetic peripheral neuropathic pain: results from a German observational study.

    PubMed

    Happich, Michael; Schneider, Edith; Boess, Frank G; Wilhelm, Stefan; Schacht, Alexander; Birklein, Frank; Ziegler, Dan

    2014-10-01

    This study aimed to compare the effectiveness of duloxetine (DLX) and the anticonvulsants pregabalin (PGB) and gabapentin (GBP) for the treatment of diabetic peripheral neuropathic pain (DPNP) in routine clinical care. Data from a 6-month, noninterventional study involving 2575 patients in whom treatment of DPNP was initiated with or changed to DLX, PGB, or GBP (n=1523) were analyzed post hoc; patients treated with other medications or combinations were excluded from this analysis. Propensity scoring was used to compare patient groups, assessing Brief Pain Inventory (BPI), Clinical and Patient Global Impression (CGI/PGI), the Hospital Anxiety and Depression Scale (HADS), the Sheehan Disability Scale (SDS), and the Short Form Health Survey (SF 12). Mean median daily dosage over 6 months was 53.9 mg for DLX (N=931), 173.5 mg for PGB (N=248), and 727.8 mg for GBP (N=351). BPI average pain severity (last observation carried forward, mean [SD]) decreased by 2.3 [2.30] points for DLX patients, and by 1.9 [2.22] in PGB, and 1.1 [2.15] in GBP patients. This difference remained statistically significant (DLX vs. PGB: P=0.029; DLX vs. GBP: P<0.001) after adjustment by propensity scores. Similar findings were also seen for the BPI interference score, CGI and PGI, the HADS anxiety score, the HADS depression score. When compared with DLX, the low doses of PGB and GBP used in this noninterventional study might have contributed to the lower effectiveness found for both anticonvulsants in the treatment of patients with DPNP.

  2. The GRACE checklist for rating the quality of observational studies of comparative effectiveness: a tale of hope and caution.

    PubMed

    Dreyer, Nancy A; Velentgas, Priscilla; Westrich, Kimberly; Dubois, Robert

    2014-03-01

    While there is growing demand for information about comparative effectiveness (CE), there is substantial debate about whether and when observational studies have sufficient quality to support decision making. To develop and test an item checklist that can be used to qualify those observational CE studies sufficiently rigorous in design and execution to contribute meaningfully to the evidence base for decision support. An 11-item checklist about data and methods (the GRACE checklist) was developed through literature review and consultation with experts from professional societies, payer groups, the private sector, and academia. Since no single gold standard exists for validation, checklist item responses were compared with 3 different types of external quality ratings (N=88 articles). The articles compared treatment effectiveness and/or safety of drugs, medical devices, and medical procedures. We validated checklist item responses 3 ways against external quality ratings, using published articles of observational CE or safety studies: (a) Systematic Review-quality assessment from a published systematic review; (b) Single Expert Review-quality assessment made according to the solicited "expert opinion" of a senior researcher; and (c) Concordant Expert Review-quality assessments from 2 experts for which there was concordance. Volunteers (N=113) from 5 continents completed 280 article assessments using the checklist. Positive and negative predictive values (PPV, NPV, respectively) of individual items were estimated to compare testers' assessments with those of experts. Taken as a whole, the scale had better NPV than PPV, for both data and methods. The most consistent predictor of quality relates to the validity of the primary outcomes measurement for the study purpose. Other