The "stiff rim" sign of hepatocellular carcinoma on shear wave elastography: correlation with pathological features and potential prognostic value

Purpose To explore the pathologic basis, the influencing factors and potential prognostic value of the stiff rim sign in two-dimensional shear wave elastography (2D-SWE) of hepatocellular carcinoma (HCC). Methods HCC patients who underwent tumor 2D-SWE examination before resection were prospectively enrolled. The stiff rim sign was defined as increased stiffness in the peritumoral region. Interobserver and intraobserver variability of the stiff rim sign was assessed. The correlation between the stiff rim sign and pathological characteristics was analyzed. Multivariate analysis was performed to examine clinical and radiological factors influencing the appearance of stiff rim sign. The Kaplan-Meier method was used to analyze the relationship between recurrence-free survival (RFS) and the stiff rim sign. Results The stiff rim sign on 2D-SWE was present in 44.7% of HCC lesions. Interobserver agreement and intraobserver agreement for the stiff rim sign were substantial (kappa = 0.772) and almost perfect (kappa = 0.895), respectively. Pathologically, the stiff rim sign was associated with capsule status, capsule integrity, capsule thickness, proportion of peritumoral fibrous tissue, and peritumoral fibrous arrangement. Multivariate analysis showed that tumor size was an independent clinical predictor for the appearance of stiff rim sign (OR 1.201, p = 0.008). Kaplan-Meier analysis showed RFS was significantly poorer in the stiff rim sign (+) group than the stiff rim sign (-) group in solitary tumors smaller than 5 cm (p = 0.007) and solitary tumors with intratumoral stiffness less than 33.7 kPa (p = 0.007). Conclusion The stiff rim sign on 2D-SWE was mainly correlated with peritumoral fibrous tissue status and was a poor prognostic indicator for HCC.