Prediction of Mortality and Hepatic Encephalopathy after Transjugular Intrahepatic Portosystemic Shunt Placement: Baseline and Longitudinal Body Composition Measurement.

PURPOSE: To investigate effects of baseline and early longitudinal body composition changes on mortality and hepatic encephalopathy (HE) after transjugular intrahepatic portosystemic shunt (TIPS). MATERIALS AND METHODS: This is a case-control study with analysis of a TIPS registry (1995-2020) including data from patients with cirrhosis with computed tomography (CT) scans obtained within 1 month before and 3 months after TIPS. Core muscle area (CMA), macroscopic subcutaneous adipose tissue (mSAT), macroscopic visceral adipose tissue (mVAT) area, and muscle adiposity index (MAI) on CT were obtained. Multipredictor Cox proportional hazards models were used to assess the effect of body composition variables on mortality or HE. RESULTS: In total, 280 patients (158 men; median age, 57.0 years; median Model for End-stage Liver Disease-sodium [MELD-Na] score, 14.0) were included. Thirty-four patients had post-TIPS imaging. Median baseline CMA was 68.3 cm2 (interquartile range, 57.7-83.5 cm2). Patients with higher baseline CMA had decreased risks of mortality (hazard ratio [HR]: 0.82; P = .04) and HE (HR: 0.82; P = .009). It improved prediction of mortality over MELD-Na and post-TIPS right atrial pressure alone (confidence interval = 0.729). An increase in CMA (HR: 0.60; P = .043) and mSAT (HR: 0.86; P = .022) or decrease in MAI (HR: 1.50; P = .049) from before to after TIPS was associated with a decreased risk of mortality. An increase in mSAT was associated with an increased risk of HE (HR: 1.11; P = .04). CONCLUSIONS: CMA on CT scan 1 month before TIPS placement predicts mortality and HE in patients with cirrhosis. Changes in body composition on CT measured 3 months after TIPS placement independently predict mortality and HE.

Assessment of Clinical Outcomes, Clinical Manifestations, and Risk Factors for Hepatic Infarction After Transjugular Intrahepatic Portosystemic Shunt Placement (TIPS): A Retrospective Comparative Study.

PURPOSE: To describe the imaging findings of hepatic infarction after transjugular intrahepatic portosystemic shunt (TIPS) placement and identify risk factors, clinical manifestations, and outcomes of infarction after TIPS. MATERIALS AND METHODS: In this retrospective analysis of a TIPS registry (1995-2021), cirrhotic patients with hepatic infarction (n = 33) and control patients without infarct (n = 33) after TIPS were identified. Laboratory values, ultrasound findings, and clinical variables were compared between groups to identify risk factors and differences in outcomes. A Cox proportional hazards regression model with propensity score was used to assess the effect of hepatic infarction on mortality and acute-on-chronic liver failure (ACLF) score. RESULTS: Hepatic infarction involved the right posterior segments (segments VI or VII) in 32 of 33 patients. Prolonged vasopressor requirement (p = 0.003) and intensive care unit stay (p = 0.001) were seen in patients with hepatic infarct, as well as trends toward lower post-TIPS portosystemic pressure gradient (p = 0.061) and higher risk of ACLF (p = 0.056). Procedure-related portal vein thrombosis or hepatic artery injury was identified in 12 and 5 patients with infarct, respectively. Patients with infarct had higher postprocedural aspartate aminotransferase (p < 0.001) and alanine aminotransferase (p < 0.001) levels, higher international normalized ratio (p = 0.016), lower platelet count (p = 0.042), and a greater decrease in hemoglobin level (p = 0.003). CONCLUSION: Hepatic infarction most frequently affects the right posterior hepatic segments after TIPS and results in a worse postprocedural course. Procedure-related complications and critically low portosystemic pressure gradient may contribute to TIPS-associated hepatic infarct.

Improving the Robustness of Diagnostic Accuracy Results By Asking Study Readers to Further Distinguish Subjects Who Appear to be Without the Condition Of Interest.

RATIONALE AND OBJECTIVES: In diagnostic accuracy studies, cases in which a reader does not see the condition of interest are often given the same score for ROC analysis (e.g. confidence score of 0%). However, many of these cases can be further distinguished and doing so may result in more robust ROC results. MATERIALS AND METHODS: We examined two recent, real-world studies which used different procedures to encourage readers to further distinguish subjects who appear to be without the condition of interest. For each study, we calculated the results under two conditions. In the "zeros distinguished" (ZD) condition, we incorporated the confidence scores collected to further distinguish the normal-looking subjects. In the "zeros not distinguished" (ZND) condition, we disregarded these scores and simply gave the unit of analysis a score of zero whenever the reader did not identify the condition of interest in that unit. We compared the two conditions on (1) coverage of the ROC space and (2) discrepancy between parametric and nonparametric results. RESULTS: Compared to the ZND condition, coverage of the ROC space was improved in the ZD condition for all ROC curves in both studies. In the first study, there was a significant reduction in the discrepancy between parametric and nonparametric results (median discrepancy in ZND vs ZD condition: 0.033 vs 0.011, p = 0.012). A similar reduction was not seen in the second study, though the discrepancies were very low in both conditions (0.003 vs 0.006, p = 0.313). CONCLUSION: Prompting readers to further distinguish cases in which they do not see the condition of interest may result in more robust ROC results, though further exploration of this topic is warranted.

Magnetic resonance imaging of deltoid muscle/tendon tears: a descriptive study.

OBJECTIVE: To describe the MRI features of deltoid tears and to evaluate tear characteristics in patient groups based on history of trauma and rotator cuff tear (RCT). MATERIALS AND METHODS: The records of patients who underwent shoulder MRI at our institution between July 2007 and June 2018 were retrospectively reviewed to identify deltoid tears, and patients were divided into groups based on history of recent trauma and presence of RCT. Images were reviewed to identify the location and size of the deltoid tear; the presence or absence of RCT, muscle atrophy, tendon retraction, humeral head subluxation, soft tissue edema, and additional pathologies were also noted. Medical records were reviewed for information about history of steroid injection, previous rotator cuff surgery, and treatments used. RESULTS: Among 69 patients with deltoid tears (45 men; mean age, 65.2 years; range, 19-89 years), patients with RCTs and no trauma had the highest frequency of deltoid tears in the middle portion (p = 0.005). Only patients with RCTs had undergone steroid injection or rotator cuff surgery. Two patients had deltoid tear without RCT and without recent trauma; these patients demonstrated evidence of calcific tendinopathy and chronic subacromial-subdeltoid bursitis. CONCLUSION: The middle (acromial) portion of the deltoid is more frequently affected in patients with RCTs than in those with trauma. Although deltoid tears are commonly associated with RCT, calcific tendinopathy and chronic bursitis may also be seen in patients with deltoid tears.

Studies of Medical Tests: Design and Analytical Considerations.

Medical tests are procedures intended to detect, diagnose, characterize, or monitor a specific medical condition. Understanding the accuracy of a medical test is a critical part of informed decision-making in patient management, as it allows clinicians to appreciate the types of errors a medical test might be prone to making and how often it makes them. Designing a study to assess the performance of a medical test, however, presents unique challenges, from acquiring a reference standard to dealing with the complexities that arise when the test involves an interpretation by a human reader. This article provides an overview of design considerations in this context, including common biases and how to avoid them, statistical considerations, and reporting guidelines. A short list of questions is also provided, which can serve as a quick reference for anyone designing, implementing, or reviewing a study that intends to assess the performance of a medical test.

Clinical utility of PSAD combined with PI-RADS category for the detection of clinically significant prostate cancer.

PURPOSE: The goal of this study was to determine the predictive value of prostate-specific antigen density (PSAD) plus Prostate Imaging Reporting and Data System (PI-RADS) category for the detection of clinically significant prostate cancer. MATERIALS AND METHODS: This retrospective study included 526 men without known prostate cancer (initial diagnosis group) and 133 men with prostate cancer grade group 1 (active surveillance group) who underwent magnetic resonance imaging-guided and/or systematic prostate biopsy procedures between August 2014 and October 2018. Prostate specific antigen (PSA), PSAD, and PI-RADS category were entered into logistic regression models for predicting clinically significant prostate cancer (grade group ≥2) at biopsy. Receiver operating characteristic curve analysis was performed to assess model accuracy. RESULTS: The area under the curve (AUC) increased when PSAD was combined with PI-RADS in the initial diagnosis group (difference in AUC = 0.031; 95% confidence interval: 0.012, 0.050; P = 0.002) but not in the active surveillance group (difference in AUC = 0.016; 95% confidence interval: -0.040, 0.071; P = 0.579). When a PSAD threshold of 0.15 was applied, the frequency of clinically significant prostate cancer in patients with a PI-RADS score of 3 or lower decreased from 9.8% to 5.6% in the initial diagnosis group and from 10.7% to 2.7% in the active surveillance group. CONCLUSIONS: The addition of PSAD improves the predictive performance of PI-RADS in men without known prostate cancer. A PSAD threshold of 0.15 can help to minimize the number of missed clinically significant prostate cancer cases in men with a PI-RADS score of 3 or lower who decide to defer biopsy.

Statistical considerations for testing an AI algorithm used for prescreening lung CT images.

Artificial intelligence, as applied to medical images to detect, rule out, diagnose, and stage disease, has seen enormous growth over the last few years. There are multiple use cases of AI algorithms in medical imaging: first-reader (or concurrent) mode, second-reader mode, triage mode, and more recently prescreening mode as when an AI algorithm is applied to the worklist of images to identify obvious negative cases so that human readers do not need to review them and can focus on interpreting the remaining cases. In this paper we describe the statistical considerations for designing a study to test a new AI prescreening algorithm for identifying normal lung cancer screening CTs. We contrast agreement vs. accuracy studies, and retrospective vs. prospective designs. We evaluate various test performance metrics with respect to their sensitivity to changes in the AI algorithm's performance, as well as to shifts in reader behavior to a revised worklist. We consider sample size requirements for testing the AI prescreening algorithm.

Scar burden is an independent and incremental predictor of cardiac resynchronisation therapy response.

Objective: Determine the prognostic impact of scar quantification (scar %) by cardiac magnetic resonance (CMR) in predicting heart failure admission, death and left ventricular (LV) function improvement following cardiac resynchronisation therapy (CRT), after controlling for the presence of left bundle branch block (LBBB), QRS duration (QRSd) and LV lead tip location and polarity. Methods: Consecutive patients who underwent CMR between 2002 and 2014 followed by CRT were included. The primary endpoint was death or heart failure admission. The secondary endpoint was change in ejection fraction (EF) ≥3 months after CRT. Cox proportional hazards, linear regression models and change in the area under the receiver operating characteristic curve (AUC) were used. Results: A total of 84 patients were included (63% male, 51% with ischaemic cardiomyopathy). After adjusting for clinical factors, presence of LBBB and QRSd and LV lead tip location and polarity, greater scar % remained associated with a higher risk for clinical events (HR=1.06; 95% CI 1.02 to 1.10; p<0.001) and a smaller improvement in EF (slope: -0.61%; 95% CI -0.93% to 0.29%; p<0.001). When adding scar % to QRSd and LBBB, there was significant improvement in predicting clinical events at 3 years (AUC increased to 0.831 from 0.638; p=0.027) and EF increase ≥10% (AUC 0.869 from 0.662; p=0.007). Conclusion: Scar quantification by CMR has an incremental value in predicting response to CRT, in terms of heart failure admission, death and EF improvement, independent of the presence of LBBB, QRSd, LV lead tip location and polarity.

Relationship between cortical thickness and fluency in the memory disorders clinic population.

As brain networks break down in neurodegenerative disorders such as Alzheimer's disease, language and executive function frequently decline. We aimed to quantify the relationship between fluency (both categorical and phonemic) and cortical thickness using data from a large cohort of patients who were undergoing assessment at a memory disorders clinic. In addition, we defined the pattern of these relationships across the four major lobes of the brain. A total of 590 patients underwent extensive psychometric testing, including categorical (animal-naming) and phonemic (FAS) tests of fluency. All patients also underwent structural MRI featuring a volumetric T1-weighted sequence that served as the input for postprocessing calculations using FreeSurfer, yielding cortical parcellations and thicknesses. The fluency-thickness relationships were summarized using Pearson's correlation coefficient. In a univariable analysis over all lobes, there were significant correlations using categorical fluency with both cortical thickness and age, with education less correlated; using phonemic fluency there were similar correlations with cortical thickness and age, but education was more correlated. Neither handedness nor sex was significantly correlated with either categorical or phonemic score. At a lobar level, for both fluency tests, scores were positively correlated with cortical thickness in all lobes; these relationships were strongest in the temporal lobe (p < 0.01). The correlations for categorical testing were generally stronger than the correlations for phonemic testing and were again strongest in the temporal lobe (r = 0.38 for categorical testing vs 0.22 for phonemic testing). The bilateral parietal lobes were more important for categorical testing than for phonemic testing, and the left frontal lobe was more important for phonemic testing than for categorical testing. Comparison of the homologous lobes between the two hemispheres demonstrated that only the frontal lobes were significantly different for both scores, with the left side having a stronger relationship with the scores (categorical: r = 0.21 for left; r = 0.14 for right; p < 0.01. phonemic: r = 0.13 for left; r = 0.08 for right; p < 0.01). In conclusion, these results demonstrated that structural MRI and fluency tests reveal a significant spatial pattern of correlations between cortical thickness and fluency, which varies with the type of fluency test.

Contemporary Outcomes in Low-Gradient Aortic Stenosis Patients Who Underwent Dobutamine Stress Echocardiography.

Background Detection of flow reserve ( FR ) by dobutamine stress echocardiography is used for risk stratification in low-gradient aortic stenosis ( AS ). Prognostic significance of dobutamine stress echocardiography in the transcatheter aortic valve replacement era is unclear. We aimed to assess the current relevance of FR . Methods and Results We studied 235 patients with low-gradient severe AS (rest aortic valve area ≤1.0 cm2 or indexed aortic valve area ≤0.60 cm2/m2; mean aortic valve gradient <40 mm Hg) and left ventricular ejection fraction <50%) with dobutamine stress echocardiography done September 2010 through July 2016. FR was defined by ≥20% stroke volume increase. We diagnosed "true-severe AS " if peak aortic valve velocity ≥4 m/s occurred with aortic valve area ≤1.0 cm2 (or indexed aortic valve area ≤0.6 cm2/m2). At a median time of 51 days, 128 patients underwent aortic valve replacement,either surgical aortic valve replacement (n=42) or transcatheter aortic valve replacement (n=86). FR was observed in 138 patients, while 86 patients had true-severe AS . During median follow-up of 2.3 years, 138 patients died. In a multivariable model, aortic valve replacement (hazard ratio 0.41, 95% CI : 0.29-0.58, P <0.001) and lower Society of Thoracic Surgeons score (hazard ratio 1.06, 95% CI : 1.04-1.09, P<0.001) were associated with better survival, while FR was not predictive. aortic valve replacement was associated with survival regardless of the presence or absence of FR or AS severity stratification. Conclusions In low-gradient AS with reduced ejection fraction, FR or AS severity stratification by dobutamine stress echocardiography was not associated with survival. Aortic valve replacement was associated with better survival in low-gradient AS independent of FR .

Receiver operating characteristic (ROC) curves: review of methods with applications in diagnostic medicine.

Receiver operating characteristic (ROC) analysis is a tool used to describe the discrimination accuracy of a diagnostic test or prediction model. While sensitivity and specificity are the basic metrics of accuracy, they have many limitations when characterizing test accuracy, particularly when comparing the accuracies of competing tests. In this article we review the basic study design features of ROC studies, illustrate sample size calculations, present statistical methods for measuring and comparing accuracy, and highlight commonly used ROC software. We include descriptions of multi-reader ROC study design and analysis, address frequently seen problems of verification and location bias, discuss clustered data, and provide strategies for testing endpoints in ROC studies. The methods are illustrated with a study of transmission ultrasound for diagnosing breast lesions.

Accuracy and Interobserver Agreement for Prostate Imaging Reporting and Data System, Version 2, for the Characterization of Lesions Identified on Multiparametric MRI of the Prostate.

OBJECTIVE: The objective of this study was to measure the accuracy and interobserver agreement of the Prostate Imaging Reporting and Data System, version 2 (PI-RADSv2), for the characterization of prostate lesions on multiparametric MRI. MATERIALS AND METHODS: This retrospective study included 170 men examined at a single institution between August 2014 and February 2015 on a 3-T MRI scanner. Study patients were found to have lesions concerning for prostate cancer that were targeted for MRI/transrectal ultrasound fusion biopsy. Two experienced readers independently assigned a PI-RADSv2 assessment category to the dominant lesion in each patient. The AUC was calculated to determine reader accuracy for the detection of clinically significant prostate cancer (Gleason score ≥ 3 + 4). The Cohen kappa statistic was used to quantify interobserver agreement. RESULTS: The prevalence of clinically significant prostate cancer was 0.36 (61/170 patients). The AUCs for readers 1 and 2 were 0.871 and 0.882, respectively. The AUCs were greater for peripheral zone lesions than for transition zone lesions. When a PI-RADSv2 assessment category ≥ 3 was considered positive, the agreement between readers was good overall (κ = 0.63) and was fair for transition zone lesions (κ = 0.53). When a PI-RADSv2 assessment category ≥ 4 was considered positive, the agreement was excellent overall (κ = 0.91) and was excellent for both peripheral zone lesions (κ = 0.91) and transition zone lesions (κ = 0.87). CONCLUSION: Two experienced readers were able to accurately identify patients with clinically significant prostate cancer using PI-RADSv2 with good interobserver agreement overall.

Clinical Utility of High-Frequency Musculoskeletal Ultrasonography in Foot and Ankle Pathology: How Ultrasound Imaging Influences Diagnosis and Management.

The use of high-frequency (high-resolution) musculoskeletal ultrasonography is increasing and has shown promising utility in many areas of medicine. The utility of musculoskeletal ultrasonography for foot and ankle complaints has not been widely investigated, however. Although some conditions of the foot and ankle are easily diagnosed by physical examination, others can have nonspecific examination findings, making optimal treatment decisions difficult. We hypothesized that high-resolution musculoskeletal ultrasound scanning of the foot and ankle can affect the diagnosis and/or treatment for patients presenting with foot or ankle complaints. Retrospectively, the cases of 98 patients who had undergone musculoskeletal ultrasound scanning of the foot or ankle were reviewed. The pre-ultrasound clinical diagnosis and treatment were compared with the post-ultrasound diagnosis and treatment. In 64% of the patients, the diagnosis or treatment changed after the ultrasound examination. In 43% of patients, both the diagnosis and the treatment changed after ultrasound scanning. For those patients for whom the diagnosis and treatment were unchanged after the ultrasound examination, the ultrasound findings were concordant with the pre-ultrasound clinical diagnosis for 100% of the patients. These results suggest that in a large proportion of patients, high-resolution musculoskeletal ultrasonography of the foot or ankle can facilitate appropriate diagnosis and management.

Administered activity and outcomes of glass versus resin (90)Y microsphere radioembolization in patients with colorectal liver metastases.

BACKGROUND: Given the differences in size, specific activity, and dosing methods for glass yttrium-90 microspheres ((90)Y-glass) and resin (90)Y microspheres ((90)Y-resin), these therapies may expose the liver to different amounts of radiation, thereby affecting their efficacy and tolerability. We aimed to compare the prescribed activity of (90)Y-glass and (90)Y-resin for real-world patients undergoing selective internal radiation therapy (SIRT) for liver-dominant metastatic colorectal cancer (mCRC) and to assess efficacy and safety outcomes in these patients. METHODS: We examined the records of 28 consecutive patients with unresectable colorectal liver metastases treated with SIRT between June 2008 and May 2011 at our institution. Using baseline CT and MR images, we calculated a projected activity as if we had used the other product and compared it to the actual prescribed activity of (90)Y-glass and (90)Y-resin for each SIRT treatment per manufacturer guidelines. Progression and adverse events were evaluated at follow up visits. Survival was analyzed by the Kaplan-Meier method. RESULTS: For (90)Y-glass treatments with a mean prescribed (90)Y activity of 1.77 GBq, the mean projected (90)Y-resin activity was 0.84 GBq. For (90)Y-resin treatments with a mean prescribed (90)Y activity of 1.05 GBq, the mean projected (90)Y-glass activity was 2.48 GBq. The median survival was 9.3 months versus 18.2 months for (90)Y-glass and (90)Y-resin, respectively (P=0.292). During the second year after SIRT, the hazard ratio of death for patients treated with (90)Y-glass versus (90)Y-resin was 4.0 (95% CI: 1.3, 12.3; P=0.017). No significant difference in progression, adverse events or liver toxicity was observed. CONCLUSIONS: Using manufacturer recommended guidelines, (90)Y-resin delivers significantly less activity than (90)Y-glass to patients with liver-dominant mCRC undergoing SIRT with no significant difference in adverse events and a trend toward improved survival.

Diagnostic Accuracy of CT Enterography for Active Inflammatory Terminal Ileal Crohn Disease: Comparison of Full-Dose and Half-Dose Images Reconstructed with FBP and Half-Dose Images with SAFIRE.

Purpose To compare the diagnostic accuracy and image quality of computed tomographic (CT) enterographic images obtained at half dose and reconstructed with filtered back projection (FBP) and sinogram-affirmed iterative reconstruction (SAFIRE) with those of full-dose CT enterographic images reconstructed with FBP for active inflammatory terminal or neoterminal ileal Crohn disease. Materials and Methods This retrospective study was compliant with HIPAA and approved by the institutional review board. The requirement to obtain informed consent was waived. Ninety subjects (45 with active terminal ileal Crohn disease and 45 without Crohn disease) underwent CT enterography with a dual-source CT unit. The reference standard for confirmation of active Crohn disease was active terminal ileal Crohn disease based on ileocolonoscopy or established Crohn disease and imaging features of active terminal ileal Crohn disease. Data from both tubes were reconstructed with FBP (100% exposure); data from the primary tube (50% exposure) were reconstructed with FBP and SAFIRE strengths 3 and 4, yielding four datasets per CT enterographic examination. The mean volume CT dose index (CTDIvol) and size-specific dose estimate (SSDE) at full dose were 13.1 mGy (median, 7.36 mGy) and 15.9 mGy (median, 13.06 mGy), respectively, and those at half dose were 6.55 mGy (median, 3.68 mGy) and 7.95 mGy (median, 6.5 mGy). Images were subjectively evaluated by eight radiologists for quality and diagnostic confidence for Crohn disease. Areas under the receiver operating characteristic curves (AUCs) were estimated, and the multireader, multicase analysis of variance method was used to compare reconstruction methods on the basis of a noninferiority margin of 0.05. Results The mean AUCs with half-dose scans (FBP, 0.908; SAFIRE 3, 0.935; SAFIRE 4, 0.924) were noninferior to the mean AUC with full-dose FBP scans (0.908; P < .003). The proportion of images with inferior quality was significantly higher with all half-dose reconstructions than with full-dose FBP (mean proportion: 0.117 for half-dose FBP, 0.054 for half-dose SAFIRE 3, 0.054 for half-dose SAFIRE 4, and 0.017 for full-dose FBP; P < .001). Conclusion The diagnostic accuracy of half-dose CT enterography with FBP and SAFIRE is statistically noninferior to that of full-dose CT enterography for active inflammatory terminal ileal Crohn disease, despite an inferior subjective image quality. (©) RSNA, 2016 Online supplemental material is available for this article.

Throwing-related injuries of the subscapularis in professional baseball players.

OBJECTIVE: To describe the MR appearance of a series of throwing-related injuries to the subscapularis muscle-tendon complex among baseball players. MATERIALS AND METHODS: A retrospective review of MR scans of the shoulder in players from 1 professional baseball organization over the course of 5 years was performed to identify cases with findings suggestive of subscapularis injury. These findings were graded and the medical record was reviewed to assess clinical findings, treatment, and follow-up. Preinjury baseline measurements of arm external rotation at 90° of abduction were compared to measurements from a noninjured cohort to evaluate whether this measure is a risk factor for injury. RESULTS: A total of 133 MR scans of the shoulder were evaluated. Eleven of the scans demonstrated signal changes suggesting subscapularis injury; 10 of these 11 patients had clinical findings supporting a diagnosis of throwing-related subscapularis strain. There were four grade 1, four grade 2, and two grade 3 injuries. All injuries occurred in the inferior half of the subscapularis at the myotendinous junction. Risk of subscapularis injury increased with lower levels of dominant arm external rotation (odds ratio, 1.12; 95% CI, 1.07-1.21; p < 0.001). A threshold of dominant arm external rotation of <106° demonstrated sensitivity of 0.700 (95% CI, 0.392-0.897) and specificity of 0.951 (95% CI, 0.888-0.982) for subscapularis injury. CONCLUSION: Throwing-related subscapularis injuries occur in the inferior half of the muscle at the myotendinous junction. Our data suggest that there is an increased risk of these injuries with lower levels of dominant arm external rotation.

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.

OBJECTIVE: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Early experience in high-resolution MRI for large vessel occlusions.

BACKGROUND: Large vessel occlusions are an important cause of ischemic stroke. Imaging goals center on identifying the site of occlusion, the size of the ischemic core and the size of the ischemic penumbra. The etiology of the occlusion is typically inferred by history and demographics, or subacutely during investigation for shunt, hypercoagulable state or other causes. Current generation vascular imaging is based primarily on lumenography. Contours of the vessel lumen on lumenography may suggest the presence of atherosclerosis, dissection or thrombus. High-resolution MRI (HRMRI) techniques can characterize wall morphology in the presence of an occlusion, which may affect clinical care by better definition of intra-occlusion wall characteristics as well as downstream vasculature normally confounded by the lack of antegrade flow. METHODS: The HRMRI databases of Cleveland Clinic and Beijing Tiantan Hospital were reviewed to identify patients with large vessel occlusions on lumenography, performed with a diagnostic quality HRMRI. Clinical data were reviewed for each patient and images were analyzed by experienced neuroradiologists at both institutions. Where possible, conventional angiography/lumenography was reviewed for comparison. RESULTS: Nine patients with large vessel cerebral artery occlusions were identified in whom HRMRI characteristics were reviewed and categorized. Images were correlated with demographics, risk factors and the working diagnosis of each case. CONCLUSIONS: HRMRI of vascular occlusions can identify wall characteristics and characterize the course and caliber of the vasculature distal to the occluded segment. This information may be useful in determining preferred approaches for endovascular revascularization.