Three unsuspected CT diagnoses of COVID-19.

PURPOSE: Coronavirus disease 2019 (COVID-19) is caused by a novel strain of coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that has quickly spread around the globe. Health care facilities in the USA currently do not have an adequate supply of COVID-19 tests to meet the growing demand. Imaging findings for COVID-19 are non-specific but include pulmonary parenchymal ground-glass opacities in a predominantly basal and peripheral distribution. METHODS: Three patients were imaged for non-respiratory-related symptoms with a portion of the lungs in the imaged field. RESULTS: Each patient had suspicious imaging findings for COVID-19, prompting the interpreting radiologist to suggest testing for COVID-19. All 3 patients turned out to be infected with COVID-19, and one patient is the first reported case of the coincident presentation of COVID-19 and an intraparenchymal hemorrhage. CONCLUSION: Using imaging characteristics of COVID-19 on abdominal or neck CT when a portion of the lungs is included, patients not initially suspected of COVID-19 infection can be quarantined earlier to limit exposure to others.

Diffusion-weighted imaging of the liver in patients with chronic liver disease: comparison of monopolar and bipolar diffusion gradients for image quality and lesion detection.

OBJECTIVE: The objective of our study was to compare diffusion-weighted imaging (DWI) sequences using a bipolar versus a monopolar single-shot echo-planar imaging (EPI) gradient design for image quality and for lesion detection and characterization in patients with liver disease. MATERIALS AND METHODS: In this retrospective study, 77 patients with chronic liver disease who underwent MRI including bipolar and monopolar DWI at 1.5 T were assessed. Two independent observers reviewed the DWI studies for image quality and the detection and characterization of liver lesions. The reference standard for diagnosis was established by consensus review of two different observers using imaging characteristics on conventional MRI sequences, lesion stability over time, pathologic correlation, or a combination of these findings. The estimated signal-to-noise ratio (SNR) of liver parenchyma and apparent diffusion coefficients (ADCs) of the liver and lesions were calculated for both sequences. ROC analysis was conducted to evaluate the performance of ADC for the diagnosis of hepatocellular carcinoma (HCC). RESULTS: Eighty-five lesions, 50 HCCs and 35 benign lesions, were detected with the reference standard in 38 patients. There was equivalent image quality for the bipolar and monopolar sequences (p = 0.24-0.42). The HCC detection rate for observers 1 and 2 was slightly better with bipolar DWI (50.0% and 52.0%, respectively) compared with monopolar DWI (44.0% and 46.0%); however, this difference did not reach statistical significance. The estimated SNR was higher with the monopolar sequence than with the bipolar sequence (p ≤ 0.001). The AUC for the ROC curve was 0.691 for bipolar DWI and 0.649 for monopolar DWI when ADC was used for the characterization of HCC, which is not a statistically significant difference (p = 0.59). CONCLUSION: The higher estimated SNR yielded by the monopolar DWI sequence did not translate into better HCC detection compared with the bipolar DWI sequence. ADC has a limited role for HCC characterization in patients with liver disease.

Hepatocellular carcinoma in chronic hepatitis C in the absence of advanced fibrosis or cirrhosis.

OBJECTIVE: The objective of our study was to describe the cross-sectional imaging appearance of hepatocellular carcinoma (HCC) in patients with chronic hepatitis C virus (HCV) infection in the absence of advanced fibrosis and cirrhosis. MATERIALS AND METHODS: This study is a retrospective review of our surgical database to identify patients with chronic HCV infection and HCC who underwent hepatectomy and who had undergone preoperative CT or MRI. Only patients with a Metavir fibrosis score of F0, F1, or F2 on pathology were included. Patients with hepatitis B virus coinfection or other causes of chronic liver disease and patients with histopathologic evidence of advanced fibrosis or cirrhosis (Metavir scores F3 and F4) were excluded. Contrast-enhanced CT or MRI examinations performed within 2 months before surgery were reviewed for the number, size, and location of tumors; tumor enhancement characteristics; and presence of macrovascular invasion. RESULTS: Two hundred forty-five resections of HCC in patients with HCV were performed in our institution from 1987 to 2012. Of this group, 26 patients (10.6%) had a Metavir fibrosis score of F0, F1, or F2; of those patients, 19 (18 men and one woman; 18 non-Asian patients and one Asian patient; mean age, 64 years) had imaging studies available for review. Twenty-one HCCs (mean size, 4.5 cm; range, 0.9-14.8 cm) were evaluated at imaging. Typical wash-in and washout characteristics were seen in 16 of 19 viable lesions (84.2%). The remaining two HCCs were completely necrotic after transarterial chemoembolization. Eighteen patients had a solitary tumor. Most tumors (15/21, 71.4%) developed in the right hepatic lobe. CONCLUSION: HCC can develop in patients with chronic HCV without advanced fibrosis or cirrhosis, most frequently in older non-Asian men, and usually appears as a large solitary tumor with a typical wash-in-washout enhancement pattern.

Diagnosis of focal nodular hyperplasia with MRI: multicenter retrospective study comparing gadobenate dimeglumine to gadoxetate disodium.

OBJECTIVE: The purpose of this article is to report the results from a multicenter retrospective MRI study comparing gadobenate dimeglumine and gadoxetate disodium for diagnosis of hepatic focal nodular hyperplasia (FNH). MATERIALS AND METHODS: Thirty patients (28 women and two men; mean age, 37.1 years) with hepatic FNH who underwent both gadobenate dimeglumine- and gadoxetate disodium-enhanced MRI at 1.5 T were assessed. MRI was performed during the arterial, portal venous, late venous, and hepatobiliary contrast-enhanced phases (10 and 20 minutes or 1-3 hours after contrast administration, respectively, for gadoxetate disodium and gadobenate dimeglumine). Qualitative (lesion conspicuity score) and quantitative (lesion signal intensity [SI] ratio and lesion contrast ratio) assessments were performed. RESULTS: In 30 patients, 51 FNHs were assessed (mean size 3.1 ± 1.5 cm). There was equivalent qualitative lesion conspicuity in the arterial phase between the two contrast agents and higher qualitative lesion conspicuity and SI ratio in the hepatobiliary phase with gadoxetate disodium (p < 0.002). Lesion contrast ratio was significantly higher in the arterial and late venous phases with gadobenate dimeglumine (p < 0.009), with no difference in the portal venous and hepatobiliary phases between the two contrast agents (p > 0.22). CONCLUSION: These results indicate an advantage for gadobenate dimeglumine for detection of FNH at the dynamic phase and for gadoxetate disodium at the hepatobiliary phase. However, the equivalent or better qualitative lesion conspicuity coupled with the ability to obtain a comprehensive evaluation of the liver within a standard 30-minute imaging window suggests that gadoxetate disodium may be a better choice for diagnosis of FNH.