Faculty Bibliography

The aim of this study was to assess changes in shear wave velocity within the pronator quadratus muscle in patients following volar plate fixation for distal radial fractures compared to the contralateral nonoperated side. Shear wave velocity values were obtained in the short and long axis of the pronator quadratus muscle, which were analyzed separately. Patients were also stratified by age below or above 66 years. Statistical analysis was performed using paired sample Wilcoxon signed rank and t tests. Pearson and Spearman rank correlations were also used. Seventeen patients (nine women and eigth men; age range 33-82, mean 62.4 years) were prospectively assessed following open reduction volar plate fixation of distal radial fracture. A statistically significant reduction in the velocities of the treated versus the nontreated side was observed in the long axis of the muscle (3.29 versus 3.59 m/second; t test p = 0.035). The data provide evidence for shear wave elastography as a quantitative measure to assess postoperative changes in muscle and a potential tool to monitor the efficacy of rehabilitation.

BACKGROUND AND AIMS: This study evaluates the performance of various magnetic resonance imaging (MRI) response criteria for the prediction of complete pathologic necrosis (CPN) of hepatocellular carcinoma (HCC) post locoregional therapy (LRT) using explant pathology as reference. METHODS: We included 61 patients (M/F 46/15, mean age 60y) who underwent liver transplantation after LRT with transarterial chemoembolization plus radiofrequency or microwave ablation (n=56), or 90Yttrium radioembolization (n=5). MRI was performed within 90 days before liver transplantation. Three independent readers assessed the following criteria: RECIST, EASL, modified RECIST (mRECIST), percentage of necrosis on subtraction images, and diffusion-weighted imaging (DWI) [qualitative (signal intensity) and quantitative (apparent diffusion coefficient, ADC)]. The degree of necrosis was retrospectively assessed at histopathology. Intraclass correlation coefficient (ICC) and Cohen's kappa were used to assess inter-reader agreement. Logistic regression and ROC analyses were used to determine imaging predictors of CPN. Pearson correlation was performed between imaging criteria and pathologic degree of tumor necrosis. RESULTS: 97 HCCs (mean size 2.3+/-1.3 cm) including 28 with CPN were evaluated. There was excellent inter-reader agreement (ICC 0.77-0.86, all methods). EASL, mRECIST, percentage of necrosis and qualitative DWI were all significant (p<0.001) predictors of CPN, while RECIST and ADC were not. EASL, mRECIST and percentage of necrosis performed similarly (AUCs 0.810-0.815) while the performance of qualitative DWI was lower (AUC 0.622). Image subtraction demonstrated the strongest correlation (r=0.71-0.72, p<0.0001) with pathologic degree of tumor necrosis. CONCLUSIONS: EASL/mRECIST criteria and image subtraction have excellent diagnostic performance for predicting CPN in HCC treated with LRT, with image subtraction correlating best with pathologic degree of tumor necrosis. Thus, MR image subtraction is recommended for assessing HCC response to LRT. LAY SUMMARY: The assessment of hepatocellular carcinoma (HCC) tumor necrosis after locoregional therapy is essential for additional treatment planning and estimation of outcome. In this study, we assessed the performance of various magnetic resonance imaging (MRI) response criteria (RECIST, mRECIST, EASL, percentage of necrosis on subtraction images, and diffusion-weighted imaging) for the prediction of complete pathologic necrosis of HCC post locoregional therapy on liver explant. Patients who underwent liver transplantation after locoregional therapy were included in this retrospective study. All patients underwent routine liver MRI within 90 days of liver transplantation. EASL/mRECIST criteria and image subtraction had excellent diagnostic performance for predicting complete pathologic necrosis in treated HCC, with image subtraction correlating best with pathologic degree of tumor necrosis.

PURPOSE: To correlate shoulder ultrasound and radiography with F-FDG PET-CT to establish FDG uptake and therefore range of metabolic activity, as defined by SUV analysis, in various symptomatic shoulder pathologies. METHODS: Retrospective database query was performed for shoulder ultrasound and PET-CT scans between January 2012 and January 2017. Patients who had both studies within 1 year were included. Age- and sex-matched control patients with PET-CT scans only were also included. Retrospective image review determined shoulder pathology, and F-FDG SUVmax was measured using regions of interest placed at the glenohumeral joint, rotator cuff/bursa, and bicipital groove. Glenohumeral and acromioclavicular osteoarthrosis was assessed by radiography using the Kellgren-Lawrence classification system. RESULTS: Thirty-three patients had both imaging studies within 1 year. Ten patients (11 cases) were included, ranging in age from 56 to 90 years (mean, 67.9 years). Control subjects were selected among patients receiving PET-CT within 1 week of symptomatic patients. Glenohumeral osteoarthrosis was mild in 3 (27%), moderate in 2 (18%), and severe in 2 (18%). Six full-thickness rotator cuff tears (55%) were identified. SUVmax means were compared between the pathologic and control groups and were significantly higher in the former: glenohumeral joint (1.96 vs 1.32; P = 0.016), rotator cuff/bursa (2.80 vs 2.0; P = 0.005), and bicipital groove (2.19 vs 1.48; P = 0.007). The highest values were seen in full-thickness rotator cuff tear and severe biceps tenosynovitis. CONCLUSIONS: Increased metabolic activity about the shoulder is associated with a spectrum of rotator cuff, glenohumeral joint, and other soft tissue pathology that can be correlated with diagnostic ultrasound findings.

Total N-acetyl-aspartate + N-acetyl-aspartate-glutamate (NAA), total creatine (Cr) and total choline (Cho) proton MRS (1 H-MRS) signals are often used as surrogate markers in diffuse neurological pathologies, but spatial coverage of this methodology is limited to 1%-65% of the brain. Here we wish to demonstrate that non-localized, whole-head (WH) 1 H-MRS captures just the brain's contribution to the Cho and Cr signals, ignoring all other compartments. Towards this end, 27 young healthy adults (18 men, 9 women), 29.9 +/- 8.5 years old, were recruited and underwent T1 -weighted MRI for tissue segmentation, non-localizing, approximately 3 min WH 1 H-MRS (TE /TR /TI = 5/10/940 ms) and 30 min 1 H-MR spectroscopic imaging (MRSI) (TE /TR = 35/2100 ms) in a 360 cm3 volume of interest (VOI) at the brain's center. The VOI absolute NAA, Cr and Cho concentrations, 7.7 +/- 0.5, 5.5 +/- 0.4 and 1.3 +/- 0.2 mM, were all within 10% of the WH: 8.6 +/- 1.1, 6.0 +/- 1.0 and 1.3 +/- 0.2 mM. The mean NAA/Cr and NAA/Cho ratios in the WH were only slightly higher than the "brain-only" VOI: 1.5 versus 1.4 (7%) and 6.6 versus 5.9 (11%); Cho/Cr were not different. The brain/WH volume ratio was 0.31 +/- 0.03 (brain approximately 30% of WH volume). Air-tissue susceptibility-driven local magnetic field changes going from the brain outwards showed sharp gradients of more than 100 Hz/cm (1 ppm/cm), explaining the skull's Cr and Cho signal losses through resonance shifts, line broadening and destructive interference. The similarity of non-localized WH and localized VOI NAA, Cr and Cho concentrations and their ratios suggests that their signals originate predominantly from the brain. Therefore, the fast, comprehensive WH-1 H-MRS method may facilitate quantification of these metabolites, which are common surrogate markers in neurological disorders.

Purpose To evaluate the diagnostic accuracies of nonenhanced magnetic resonance (MR) imaging and MR arthrography for diagnosis of superior labrum anterior-to-posterior (SLAP) tears by using a systematic review and meta-analysis. Materials and Methods A comprehensive literature search was performed on the two main concepts of MR imaging (MR imaging, and direct and indirect MR arthrography) and SLAP tears. Inclusion criteria consisted of original studies that assessed the diagnostic accuracy of MR imaging, direct MR arthrography, and/or indirect MR arthrography for the detection of SLAP tears, by using surgical findings as the reference standard. The Quality Assessment of Diagnostic Accuracy Studies 2, or QUADAS-2 Quality Assessment of Diagnostic Accuracy Studies 2 Quality Assessment of Diagnostic Accuracy Studies 2 , tool was used to assess methodologic quality. Meta-analyses were performed that compared MR imaging studies to direct MR arthrography studies and indirect MR arthrography studies, 3-T studies to 1.5-T studies, and low-bias MR imaging studies to low-bias direct MR arthrography studies. Study variation was analyzed by using the Cochran Q test of heterogeneity and the I2 statistic. Results Thirty-two studies met inclusion and exclusion criteria, including 3524 imaging examinations: 1963 direct MR arthrography examinations (23 studies), 1402 MR examinations (14 studies), and 159 indirect MR arthrography examinations (three studies). Twelve studies had low risk for bias, two had questionable risk, and 18 had high risk. Mean sensitivities of direct MR arthrography, MR imaging, and indirect MR arthrography for SLAP tear diagnosis were 80.4%, 63.0%, and 74.2%, respectively. Mean specificities of direct MR arthrography, MR imaging, and indirect MR arthrography were 90.7%, 87.2%, and 66.5%, respectively. Summary receiver operator characteristic (ROC) curve demonstrated superior accuracy of direct MR arthrography compared with those of MR imaging and indirect MR arthrography. Similar findings were observed in the low-bias subanalysis. Summary ROC curve demonstrated overall superiority of 3-T imaging, with or without intra-articular contrast material compared with 1.5-T imaging, with or without intra-articular contrast material. Significant variance was observed for MR imaging and direct MR arthrography (P < .001) studies for both mean sensitivity and specificity. Conclusion Direct MR arthrography appears to be more accurate than nonenhanced MR imaging for diagnosis of SLAP tears, whereas 3-T MR imaging with or without intra-articular contrast material appears to improve diagnostic accuracy compared with 1.5-T MR imaging with or without intra-articular contrast material. (c) RSNA, 2017 Online supplemental material is available for this article.

Although MRI assessment of white matter lesions is essential for the clinical management of multiple sclerosis, the processes leading to the formation of lesions and underlying their subsequent MRI appearance are incompletely understood. We used proton MR spectroscopy to study the evolution of N-acetyl-aspartate (NAA), creatine (Cr), choline (Cho), and myo-inositol (mI) in pre-lesional tissue, persistent and transient new lesions, as well as in chronic lesions, and related the results to quantitative MRI measures of T1-hypointensity and T2-volume. Within 10 patients with relapsing-remitting course, there were 180 regions-of-interest consisting of up to seven semi-annual follow-ups of normal-appearing white matter (NAWM, n = 10), pre-lesional tissue giving rise to acute lesions which resolved (n = 3) or persisted (n = 3), and of moderately (n = 9) and severely hypointense (n = 6) chronic lesions. Compared with NAWM, pre-lesional tissue had higher Cr and Cho, while compared with lesions, pre-lesional tissue had higher NAA. Resolving acute lesions showed similar NAA levels pre- and post-formation, suggesting no long-term axonal damage. In chronic lesions, there was an increase in mI, suggesting accumulating astrogliosis. Lesion volume was a better predictor of axonal health than T1-hypointensity, with lesions larger than 1.5 cm3 uniformly exhibiting very low (<4.5 millimolar) NAA concentrations. A positive correlation between longitudinal changes in Cho and in lesion volume in moderately hypointense lesions implied that lesion size is mediated by chronic inflammation. These and other results are integrated in a discussion on the steady-state metabolism of lesion evolution in multiple sclerosis, viewed in the context of conventional MRI measures. Hum Brain Mapp, 2017. (c) 2017 Wiley Periodicals, Inc.

PURPOSE: To use patient-generated data to assess the changing role of emergency department (ED) imaging for a spectrum of clinical indications. METHODS: The Household Component Emergency Room Visits File was obtained from 1996 through 2014 for the Medical Expenditure Panel Survey, a nationally representative survey of US households. Percentage of visits associated with various imaging modalities was computed annually, stratified by respondents' self-reported primary condition during the visit. Modality characteristics were assessed for conditions most frequently imaged in 1996 or 2014. RESULTS: For most conditions, use of advanced imaging (defined by Medical Expenditure Panel Survey as CT or MRI) in the ED increased significantly (P < .001). The largest growth occurred for urinary calculus (from 0% to 48.5%) and headache (from 17.5% to 33.3%), which were the most commonly imaged conditions by CT or MRI in 2014. For ultrasound, the most commonly imaged condition was pregnancy in 1996 (32.9%) and 2014 (44.5%). No other condition was associated with ultrasound in >20% of visits. For radiography, the most commonly imaged conditions were extremity wounds and fractures in 1996 (range 84.5%-90.2%) and 2014 (range 93.4%-93.9%). Use of radiography decreased for urinary calculus from 67.4% to 24.2% (P < .001). CONCLUSION: For many conditions, ED utilization of advanced imaging increased significantly, though growth was variable across conditions. In certain scenarios, advanced ED imaging is adding to, rather than replacing, other modalities. Ultrasound and radiography utilization was overall unchanged. That national patient survey data mirror traditional claims-based studies suggests an expanded role for patient-generated data in identifying areas of imaging utilization that may benefit from targeted optimization efforts.

Disclosures: All authors have disclosed no financial interests, arrangements or affiliations in the context of this activity. Purpose or Case Report: Current MRI evaluation of appendicitis is limited by duration of examination and patient cooperation. The radially sampled 3D T1 weighted, gradient recalled echo sequence (radial VIBE) is a free-breathing, motion robust sequence that may prove useful in the evaluation of appendicitis in children. The purpose of this investigation is to determine the detection rate of the normal appendix with contrast enhanced (CE) radial VIBE alone compared with CE conventional 3D gradient recalled echo volumetric interpolated breath-hold examination (conventional VIBE) alone and multi-sequence abdominal pelvic MRI including CE radial VIBE. Methods& Materials:We conducted a retrospective, HIPAA compliant and IRB approved study of patients between 7 and 18 years of age who underwent an abdominal and pelvic contrast enhanced MRI between January 1, 2012 and April 1, 2016. Patients with active right lower quadrant inflammation, pelvic masses, or history of appendectomy were excluded. Visualization of the appendix was assessed by two pediatric radiologists with Certificates of Added Qualification by consensus on the following sequences: CE radial VIBE only, CE conventional VIBE only, and multi-sequence MRI which included CE radial VIBE and at least an axial or coronal single shot fast spin echo (SSFSE) or axial T2 weighted spin echo with fat suppression. The detection rates of the appendix for each sequence or combination of sequences were compared with a McNemar test. Results: Ninety-six patients met inclusion criteria. The detection rate of the normal appendix on CE radial VIBE was significantly higher than on CE conventional VIBE (76% vs 57.3%, p=0.003). The detection rate of the normal appendix with multi-sequence MRI was significantly higher than on CE conventional VIBE (81.3% vs 57%, p<0.001). There was no significant difference between the detection rate of the normal appendix on CE radial VIBE and multi-sequence MRI (76% vs 81.3%, p=0.267). When the appendix was not visualized on the CE radial VIBE (n=23) but detected on the multi-sequence MRI (n=9), it was most often visualized on SSFSE (n=8). Conclusions: CE radial VIBE allows superior detection of the normal appendix compared to CE conventional VIBE. The detection rate of the normal appendix on CE radial VIBE alone is nearly as good as when the CE radial VIBE is interpreted with additional sequences

OBJECTIVE: To assess the effect of low dose computed tomography pulmonary angiography (CTPA) on radiation dose in pregnant patients. MATERIALS AND METHODS: An old CTPA protocol for pregnant patients was compared to a new protocol. Protocol changes included: decreased kVp; increased contrast injection rate; imaging after shallow inspiration. Patients undergoing CTPA before (phase 1 group) or after (phase 2 group) the protocol change, were assessed. RESULTS: Effective dose was lower in the phase 2 group (0.95 v 1.66 mSv; p<0.001). Quantitative noise was lower in the phase 1 group (p<0.001). CONCLUSION: Low dose CTPA tailored for pregnancy reduces dose in pregnant patients.

Purpose To compare standard diffusion-weighted (DW) imaging and diffusion kurtosis (DK) imaging for prostate cancer (PC) detection and characterization in a large patient cohort, with attention to the potential added value of DK imaging. Materials and Methods This retrospective institutional review board-approved study received a waiver of informed consent. Two hundred eighty-five patients with PC underwent 3.0-T phased-array coil prostate magnetic resonance (MR) imaging, including a DK imaging sequence (b values 0, 500, 1000, 1500, and 2000 sec/mm2) before prostatectomy. Maps of apparent diffusion coefficient (ADC) and diffusional kurtosis (K) were derived by using maximal b values of 1000 and 2000 sec/mm2, respectively. Mean ADC and K were obtained from volumes of interest (VOIs) placed on each patient's dominant tumor and benign prostate tissue. Metrics were compared between benign and malignant tissue, between Gleason score (GS) /= 3 + 4 tumors, and between GS /= 4 + 3 tumors by using paired t tests, analysis of variance, receiver operating characteristic (ROC) analysis, and exact tests. Results ADC and K showed significant differences for benign versus tumor tissues, GS /= 3 + 4 tumors, and GS /= 4 + 3 tumors (P < .001 for all). ADC and K were highly correlated (r = -0.82; P < .001). Area under the ROC curve was significantly higher (P = .002) for ADC (0.921) than for K (0.902) for benign versus malignant tissue but was similar for GS /= 3 + 4 tumors (0.715-0.744) and GS /= 4 + 3 tumors (0.694-0.720) (P > .15). ADC and K were concordant for these various outcomes in 80.0%-88.6% of patients; among patients with discordant results, ADC showed better performance than K for GS /= 4 + 3 tumors (P = .016) and was similar to K for other outcomes (P > .136). Conclusion ADC and K were highly correlated, had similar diagnostic performance, and were concordant for the various outcomes in the large majority of cases. These observations did not show a clear added value of DK imaging compared with standard DW imaging for clinical PC evaluation. (c) RSNA, 2017 Online supplemental material is available for this article.