Targetoid appearance on T2-weighted imaging and signs of tumor vascular involvement: diagnostic value for differentiating HCC from other primary liver carcinomas

• Published in: European radiology 2021-09, Vol.31 (9), p.6868-6878
• Main Authors: Cannella, Roberto, Fraum, Tyler J., Ludwig, Daniel R., Borhani, Amir A., Tsung, Allan, Furlan, Alessandro, Fowler, Kathryn J.
• Format: Article
• Language: English
• Subjects: Carcinoma; Computed tomography; Diagnosis; Diagnostic Radiology; Hepatobiliary-Pancreas; Hepatocellular carcinoma; Imaging; Internal Medicine; Interventional Radiology; Liver; Liver cancer; Liver transplantation; Magnetic resonance imaging; Malignancy; Medical diagnosis; Medical imaging; Medicine; Medicine & Public Health; Neuroradiology; Occlusion; Programmable logic controllers; Radiology; Risk analysis; Risk factors; Tethering; Tumors; Ultrasound
• ISSN: 0938-7994; 1432-1084
• DOI: 10.1007/s00330-021-07743-x

Objectives To evaluate targetoid appearance on T2-weighted imaging and signs of tumor vascular involvement as potential new LI-RADS features for differentiating hepatocellular carcinoma (HCC) from other non-HCC primary liver carcinomas (PLCs). Methods This IRB-approved, retrospective study was performed at two liver transplant centers. The final population included 375 patients with pathologically proven lesions imaged between 2007 and 2017 with contrast-enhanced CT or MRI. The cohort consisted of 165 intrahepatic cholangiocarcinomas and 74 combined hepatocellular-cholangiocarcinomas, with the addition of 136 HCCs for control. Two abdominal radiologists (R1; R2) independently reviewed the imaging studies (112 CT; 263 MRI) and recorded the presence of targetoid appearance on T2-weighted images and features of tumor vascular involvement including encasement, narrowing, tethering, occlusion, and obliteration. The sensitivity and specificity of each feature were calculated for the diagnosis of non-HCC PLCs. Cohen’s kappa ( k ) test was used to assess inter-reader agreement. Results The sensitivity of targetoid appearance on T2-weighted images for the diagnosis of non-HCC PLCs was 27.5% and 32.6% (R1 and R2) and the specificity was 98.2% and 97.3% (R1 and R2). Among the features of tumor vascular involvement, those providing the highest sensitivity for non-HCC PLCs were vascular encasement (R1: 34.3%; R2: 37.2%) and obliteration (R1: 25.5%; R2: 29.7%). The highest specificity for non-HCC PLCs was provided by tethering (R1: 100%; R2: 97.1%) and occlusion (R1: 99.3%; R2: 99.3%). The inter-reader agreement was moderate to substantial ( k = 0.48–0.77). Conclusions Targetoid appearance on T2-weighted images and features of tumor vascular involvement demonstrated high specificity for non-HCC malignancy. Key Points • Targetoid appearance on T2-weighted imaging and signs of tumor vascular involvement have high specificity (92–100%) for the diagnosis of non-HCC PLCs, regardless of the presence of liver risk factors. • In the subset of patients with risk factors for HCC, the sensitivity of signs of tumor vascular involvement decreases for both readers (1.7–20.3%), while the specificity increases reaching values higher than 94.2%. • The inter-reader agreement is substantial for targetoid appearance on T2-weighted images (k = 0.74) and moderate to substantial for signs of tumor vascular involvement (k = 0.48–0.77).