ACR Ultrasound Liver Reporting and Data System: Multicenter Assessment of Clinical Performance at One Year.

PURPOSE: The aim of this study was to evaluate the clinical performance of the ACR's Ultrasound Liver Reporting and Data System (US LI-RADS™) for detecting hepatocellular carcinoma (HCC) in patients at high risk for HCC. METHODS: In this retrospective, multicenter study, 2,050 patients at high risk for HCC (1,078 men and 972 women; mean age, 57.7 years) at five sites in the United States had undergone screening liver ultrasound from January 2017 to February 2018, and US LI-RADS observation categories and visualization scores were assigned on a clinical basis. Ultrasound reports and patient records were retrospectively reviewed and follow-up imaging studies and/or pathologic reports recorded. Descriptive statistics were generated, and multivariate logistic regression analysis was used to analyze the relationship of clinical and reader-based predictors of limited visualization. Diagnostic performance data were calculated in the subset of patients with confirmatory testing. RESULTS: The most common indications for HCC screening were cirrhosis (n = 1,054 [51.4%]), noncirrhotic hepatitis B virus infection (n = 555 [27.1%]), and noncirrhotic hepatitis C virus infection (n = 234 [11.4%]). US LI-RADS observation categories assigned were US-1 (negative) in 90.4% (n = 1,854), US-2 (subthreshold) in 4.6% (n = 95), and US-3 (positive) in 4.9% (n = 101). Visualization scores were A (no or minimal limitations) in 76.8% (n = 1,575), B (moderate limitations) in 18.9% (n = 388), and C (severe limitations) in 4.2% (n = 87). Confirmatory tests, including multiphase contrast-enhanced CT or MRI (n = 331) or histopathology (n = 18), were available for 349 patients (17.0%). The sensitivity of US LI-RADS in this subset of patients was 82.4%, specificity was 74.2%, positive predictive value was 35.3%, and negative predictive value was 96.1%. CONCLUSIONS: Approximately 90% of US LI-RADS screening examinations were negative, 5% subthreshold, and 5% positive. Visualization scores were diagnostically acceptable in the vast majority (>95%) of examinations. US LI-RADS emphasized sensitivity and negative predictive value, which are key characteristics of a screening test.

Utility and Accuracy of Primary and Secondary Ultrasonographic Signs for Diagnosing Acute Appendicitis in Pediatric Patients.

Introduction Making an accurate diagnosis of acute appendicitis (AA) is vital to prevent the morbid complications associated with untreated AA. This is challenging in up to 30% of pediatric patients which is a significantly high number. Ultrasound (US) has been generally used as the initial mode of imaging in pediatric patients due to the lack of ionizing radiation. Given its variable accuracy, adjuvants such as secondary signs can be used to aid the radiologist in making an accurate diagnosis. Materials and methods Patients between the ages of two and sixteen years with acute abdominal pain suspicious for AA, who underwent right lower quadrant US between 2003 and 2016, were retrospectively identified. Corresponding computed tomography (CT) and histopathology findings were noted. Based on the presence of primary and secondary signs, results were classified into three groups to determine accuracy. Group 1 included all patients with a normal appendix or if the appendix was not visualized, no secondary signs were present. Group 2 patients were those in which the appendix was not clearly seen and they had one or more secondary signs of AA. Group 3 included all patients with primary signs of AA. The number of secondary signs and cases with perforated appendices were also correlated with sonographic accuracy. Results One thousand one hundred and fifteen patients met the inclusion criteria of which 29% had confirmatory AA. The positive appendectomy rate was 89% (337/380). Using a 3-category classification of US results, the sensitivity was 79%, specificity 97%, positive predictive value was 93%, negative predictive value was 91% and the overall accuracy was 91%. The presence of two or more secondary signs had a high likelihood of appendicitis. The perforation rate was 10% with the highest percentage seen in Group 2 patients. Conclusion Despite inescapable limiting factors, US should be used as first-line imaging for suspected appendicitis in pediatric patients especially since its accuracy rivals CT when the appendix is visualized. The use of secondary sonographic signs has solid potential to aid the radiologist in making an accurate diagnosis with our study demonstrating a proportional relationship between the number of secondary signs and the likelihood of true appendicitis. However, further investigation is needed to determine the individual accuracy of secondary signs and whether a certain combination of secondary signs has a higher association with appendicitis.