BACKGROUND. A multisystem inflammatory syndrome in children (MIS-C) associated with coronavirus disease (COVID-19) has recently been described. OBJECTIVE. The purpose of our study was to evaluate the imaging findings of MIS-C associated with COVID-19. METHODS. Imaging studies and medical records of patients (age range, 0-20 years) admitted with MIS-C between April 22 and May 21, 2020, were retrospectively reviewed. Thoracic imaging studies were evaluated for parenchymal, mediastinal and hilar, and cardiovascular abnormalities. Abdominal imaging studies were evaluated for abnormalities of solid viscera, hollow viscera, and the peritoneum as well as the mesentery and retroperitoneum. Studies were reviewed independently by two radiologists, and disagreements were resolved by a third senior radiologist. RESULTS. Sixteen patients (10 male and six female patients; age range, 20 months-20 years) were included in this study. All 16 patients presented with fever. Other presenting signs and symptoms included the following: vomiting (12/16, 75%), abdominal pain (11/16, 69%), rash (10/16, 63%), conjunctivitis (8/16, 50%), diarrhea (7/16, 44%), headache (6/16, 38%), and sore throat (5/16, 31%). Shortness of breath and cough were each present in one patient. Chest radiography showed cardiomegaly (10/16, 63%), congestive heart failure or cardiogenic pulmonary edema (9/16, 56%), atelectasis (9/16, 56%), pleural effusions (7/16, 44%), acute respiratory distress syndrome (2/16, 13%), and pneumonia (1/16, 6%). Eight patients (50%) were evaluated for pulmonary embolism (PE) (six [75%] by CT angiography [CTA] and two [25%] by ventilation-perfusion scintigraphy). In two of the eight patients (25%), CTA showed a segmental PE. Abdominal imaging findings (ultrasound, CT, and radiography) included small-volume ascites (6/16, 38%), hepatomegaly (6/16, 38%), echogenic kidneys (5/16, 31%), bowel wall thickening (3/16, 19%), gallbladder wall thickening (3/16, 19%), mesenteric lymphadenopathy (2/16, 13%), splenomegaly (1/16, 6%), and bladder wall thickening (1/16, 6%). The frequencies of findings based on all the reviewed modalities were as follows: cardiomegaly (12/16, 75%), pleural effusion (10/16, 63%), and atelectasis (10/16, 63%). Absolute interobserver agreement was 0.69-1 for thoracic findings and 0.17-1 for abdominal findings. Fifteen patients (94%) were discharged from the hospital (length of hospital stay: range, 3-20 days), and one patient remained in the hospital at the end of the study period. There were no mortalities. CONCLUSION. MIS-C associated with COVID-19 is characterized predominantly by cardiovascular abnormalities, although solid visceral organ, gallbladder, and bowel abnormalities as well as ascites are also seen, reflecting a multisystemic inflammatory process. CLINICAL IMPACT. The constellation of imaging findings in the setting of COVID-19 may alert radiologists to the diagnosis of MIS-C before rapid deterioration of patients.

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