Abdominopelvic CT in COVID-19 patients with abdominal complaints including both waves and controls: reader agreement and overcalls after consensus review.

BACKGROUND: Since many COVID-19 publications lack consensus reviews or controls, interpretive accuracy is unclear; abdominal processes unique or infrequent during the pandemic remain unknown. The incidence and nature of CT findings accounting for abdominal complaints in COVID patients, reader agreement and overcalling will be determined. METHODS: A retrospective study was performed on COVID patients with abdominal complaints from 3/15/2020-5/31/2020 and 11/1/2020-4/15/2021 including matched controls. Reviewers blinded to initial reads interpreted abdominopelvic CT exams, with discordant cases resolved in consensus. Reader agreement was measured by Cohen's Kappa, differences between cohorts by permutation tests and factors affecting false positive/negative rates by Fisher's Exact Test and logistic regression. RESULTS: 116 first wave (average age 65 years [±15.3], 63 [54%] women) and 194 second wave COVID cases (average age 64 years [±16.3], 103 [53%] women) including 116 wave 1 and 194 wave 2 prepandemic controls were included. Concordance was lower among COVID cases than controls (Cohen's Kappa of 0.58 vs. 0.82 [p ≤ 0.001]) and among wave 1 than wave 2 cases (Cohen's Kappa of 0.45 vs. 0.66 [p = 0.052]). With true positives defined as consensus between the initial reader and study reader, false positive rates were higher among COVID cases than controls (OR = 0.42, p = 0.003) and for initial than study reader (OR = 0.36, p ≤ 0.001), but lower in wave 2 than 1 (OR = 0.5, p = 0.028). CONCLUSION: Greater reader disagreement occurred during COVID than prepandemic with no reader bias as both initial and study readers called more false positives among COVID cases than controls. More overcalling occurred during COVID with colitis and cystitis most common.

Efficacy of Multi-Detector Computed Tomography for the Diagnosis of Medullary Sponge Kidney.

OBJECTIVE: To expand the diagnostic armamentarium for medullary sponge kidney (MSK), we evaluate the use of high-resolution multidetector computed tomography (MDCT) for MSK diagnosis and compare to the standard intravenous urography (IVU). Despite a significant prevalence amongst stone formers, diagnosis of this well described condition has declined. IVU, the gold standard in MSK diagnosis, has largely been replaced by CT, which has previously been shown unable to demonstrate signs of MSK. METHODS AND MATERIALS: Patients with known history of MSK based on IVU underwent limited MDCT urogram. Control group patients, without MSK, also had MDCT urograms performed for other clinically indicated conditions. Studies were scored by board-certified radiologists on a 0-2 scale based on the likelihood of MSK. IVU studies, when available, were similarly graded. RESULTS: MDCT was diagnostic of MSK in 9 out of the 10 patients with known history of MSK. No false positives were present in our series. The one case of MSK not detected on MDCT was graded as a "1" on its respective IVU. Sensitivity and specificity were 90 and 100%, respectively, when compared with IVU. CONCLUSION: Concordance with IVU findings, despite a small reduction in sensitivity, indicates MDCT to be a suitable, and more readily available replacement for IVU in the diagnosis of MSK.

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

OBJECTIVE: 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). MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: Visceral abdominal fat area calculated from a single abdominal MDCT slice obtained in children is highly correlated with total visceral abdominal fat and with BMI and involves limited radiation exposure.

Renal medullary carcinoma: CT and MRI features.

OBJECTIVE: We review the cross-sectional imaging findings of six cases of pathologically proven renal medullary carcinoma in patients with sickle cell trait. MRI findings were available in three of the patients. To our knowledge, only one previous report has addressed MRI features of this rare disease. CONCLUSION: In young patients with sickle cell trait, an infiltrative renal mass with associated retroperitoneal adenopathy and caliectasis are characteristic findings of renal medullary carcinoma on CT and MRI.