This copy is for personal use only. To order printed copies, contact reprints@rsna.org I n P r e s s Abbreviations: ICU = intensive care unit; ACE2 = angiotensin converting enzyme 2; COVID-19 = Coronavirus disease 2019; RUQ = right upper quadrant; SARS-CoV-2 = Severe acute respiratory syndrome coronavirus 2.Key Results: -33% of inpatients with COVID-19 had abdominal imaging and 17% had cross-sectional imaging. Imaging was associated with age (OR 1.03 per year increase) and intensive care unit (ICU) admission (OR 17.3). -54% of right upper quadrant ultrasounds demonstrated findings of cholestasis. -31% of CTs showed bowel wall abnormalities. Signs of late ischemia were seen on 20% of CTs in ICU patients (2.7% of ICU patients), with pathologic correlation suggesting small vessel thrombosis. Summary Statement: Bowel abnormalities, including ischemia, and cholestasis were common findings on abdominal imaging of inpatients with COVID-19. I n P r e s s Abstract:Background: Angiotensin converting enzyme 2 (ACE2), a target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), demonstrates its highest surface expression in the lung, small bowel, and vasculature, suggesting abdominal viscera may be susceptible to injury.Purpose: To report abdominal imaging findings in patients with coronavirus disease 2019 . Materials and Methods:In this retrospective cross-sectional study, patients consecutively admitted to a single quaternary care center from 3/27/2020 to 4/10/2020 who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were included. Abdominal imaging studies performed in these patients were reviewed and salient findings recorded.Medical records were reviewed for clinical data. Univariable analysis and logistic regression were performed. Results: 412 patients (average age 57 years; range 18->90 years; 241 men, 171 women) were evaluated. 224 abdominal imaging studies were performed (radiographs, n=137; ultrasound, n=44; CT, n=42; MRI, n=1) in 134 patients (33%). Abdominal imaging was associated with age (odds ratio [OR] 1.03 per year increase, p=0.001) and ICU admission (OR 17.3, p<0.001). Bowel wall abnormalities were seen on 31% of CT scans (13 of 42) and were associated with ICU admission (OR 15.5, p=0.01). Bowel findings included pneumatosis or portal venous gas, seen on 20% of CT scans in ICU patients (4 of 20). Surgical correlation (n=4) revealed unusual yellow discoloration of bowel (n=3) and bowel infarction (n=2). Pathology demonstrated ischemic enteritis with patchy necrosis and fibrin thrombi in arterioles (n=2). Of right upper quadrant ultrasounds, 87% (32 of 37) were performed for liver laboratory findings, and 54% (20 of 37) demonstrated a dilated sludge-filled gallbladder suggestive of cholestasis. Patients with a cholecystostomy tube placed (n=4) had negative bacterial cultures. Conclusion: Bowel abnormalities and cholestasis were common findings on abdominal imaging of inpatients with COVID-19. Patients who went to laparotomy often had ischemia, possibly due to sma...

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SUMMARY -We assess a diffusion-weighted imaging (DWI) analysis technique as a potential basis for computer-aided diagnosis (CAD

We prospectively compared the ability of neuroradiologists to diagnose medulloblastoma with novice raters using only apparent diffusion coefficient (ADC) values measured on ADC maps. One hundred and three pediatric patients with pre-operative magnetic resonance imaging scans showing a posterior fossa tumor with histological verification were retrospectively identified from a ten-year period at a tertiary care medical center. A single observer measured the lowest ADC values in all tumors to determine the mean minimum ADC (ADCmin) value that provided greatest accuracy in distinguishing medulloblastomas from other tumors, which was determined to be 0.66×10(-3) mm(2)/s. Imaging studies, including ADC maps, from 90 patients were provided to two neuroradiologists, who provided a diagnosis, which was later dichotomized as medulloblastoma or other. Two medical students measured ADCmin within tumors and those with ADCmin < 0.66×10(-3) mm(2)/s were recorded as medulloblastoma; any other value was recorded as other. Diagnostic accuracy was measured. ADCmin values allowed a correct identification of lesions as either medulloblastoma or other in 91% of cases. After diagnoses by the two neuroradiologists were categorized as either medulloblastoma or other, their diagnoses were correct in 90% and 84% of cases, respectively. In 19 cases, at least one neuroradiologist was incorrect; the addition of ADC values to clinical interpretation would have allowed a correct diagnosis in 63% of such cases. Diagnostic accuracy based on ADC values by medical students was comparable to that of subspecialty-trained neuroradiologists. Our findings suggest that the addition of ADC values to standard film interpretation may improve the diagnostic rate for these tumors.

Summary Objective This study examined the relationship between histological variables and DTI values in a normal canine brain. We hypothesized that radial diffusivity (RD) would correlate with myelin density and fractional anisotropy (FA) would correlate with white matter fiber coherence Specimens and methods We acquired DTI maps of a normal canine brain post mortem on a 7T MR scanner (TR = 100 ms, TE = 18.1 ms, NEX = 1, width [d] = 4 ms, separation [D] = 8.9 ms, gradient amplitude = 600 mT/m, b=1,565 s/mm2) and generated maps of FA, RD, and axial diffusivity. The brain was subsequently sectioned and stained for myelin with gold chloride, which also allowed for measurement of fiber coherence. DTI metrics were then directly compared with optical density of the myelin stain and the coherence of stained fibers. Results Multivariate linear regression demonstrated that RD, but not FA, significantly correlated with both myelin stain intensity (p = 0.031) and fiber coherence (p = 0.035). The Pearson correlation coefficient between these two histological variables and FA was 0.122; and was 0.607 for the histological variables and RD. Conclusion We found that RD significantly correlated with both optical density of myelinated fibers and fiber coherence, but FA correlated with neither histological finding. Factors other than degree of myelination and fiber coherence should be considered to fully account for regional variation in FA.