Evaluation of treatment response in hepatocellular carcinoma in the explanted liver with Liver Imaging Reporting and Data System version 2017

Abstract

Objective: To investigate the performance of Liver Imaging Reporting and Data System (LI-RADS) v2017 treatment response algorithm for predicting hepatocellular carcinoma (HCC) viability after locoregional therapy (LRT) using the liver explant as reference.

Methods: One hundred fourteen patients with 206 HCCs who underwent liver transplantation (LT) after LRT for HCCs were included in this retrospective study. Two radiologists independently evaluated tumor viability using the LI-RADS and modified RECIST (mRECIST) with CT and MRI, respectively. The sensitivity and specificity of arterial phase hyperenhancement (APHE) and LR-TR viable criteria (any of three findings: APHE, washout, and enhancement pattern similar to pretreatment imaging) were compared using logistic regression. Receiver operating characteristics (ROC) analysis was used to compare the diagnostic performance between LI-RADS and mRECIST and between CT and MRI.

Results: The sensitivity and specificity for diagnosing viable tumor were not significantly different between APHE alone and LR-TR viable criteria on CT (p = 0.054 and p = 0.317) and MRI (p = 0.093 and p = 0.603). On CT, the area under the ROC curve (AUC) of LI-RADS was significantly higher than that of mRECIST (0.733 vs. 0.657, p < 0.001). On MRI, there was no significant difference in AUCs between LI-RADS and mRECIST (0.802 vs. 0.791, p = 0.500). Intra-individual comparison of CT and MRI showed comparable AUCs using LI-RADS (0.783 vs. 0.795, p = 0.776).

Conclusions: LI-RADS v2017 treatment response algorithm showed better diagnostic performance than mRECIST on CT. With LI-RADS, CT and MRI were comparable to diagnose tumor viability of HCC after LRT.

Key points: • Using Liver Imaging Reporting and Data System (LI-RADS) v2017 treatment response algorithm, the viability of hepatocellular carcinoma (HCC) after locoregional therapy (LRT) can be accurately diagnosed. • LI-RADS v2017 treatment response algorithm is superior to modified Response Evaluation Criteria in Solid Tumors for evaluating HCC viability using CT. • Either CT or MRI can be performed to assess tumor viability after LRT using LI-RADS v2017 treatment response algorithm.

Keywords: Hepatocellular carcinoma; Liver transplantation; Magnetic resonance imaging; Multidetector computed tomography; Therapeutic chemoembolization.

Figure 1.

Flow diagram of patients included in the study.

Figure 2.

A 56-year old man with hepatocellular carcinoma (HCC) who underwent transarterial chemoembolization (TACE). Pre-treatment axial CT images obtained during late arterial phase (A) and delayed phase (B) show a 3-cm arterial enhancing and washout mass in the liver dome, suggestive of HCC (LR-5). After TACE, axial CT images obtained during late arterial phase (C) and delayed phase (D) show washout (arrows) without definite arterial enhancement surrounding lipiodolized nodule in the liver dome. Liver Imaging Reporting and Data System (LI-RADS) v2017 treatment response algorithm revealed viable tumor (LR-TR viable), whereas modified Response Evaluation Criteria in Solid Tumors (mRECIST) revealed nonviable tumor. Based on pathology examination, the lesion was diagnosed as 2.8-cm sized HCC with 50% necrosis.

Figure 3.

A 56-year old man with hepatocellular carcinoma (HCC) who underwent transarterial chemoembolization (TACE). Post-TACE CT images obtained at precontrast (A), late arterial phase (B), and portal venous phase (C) show partial lipiodolized mass in the liver segment IV. Lipiodol-defect area (arrows) reveals questionable nodular arterial enhancement and washout. This lesion was categorized as LR-TR equivocal through LI-RADS v2017 treatment response algorithm, and nonviable tumor through mRECIST. On post-TACE T1-weighted MR images obtained at precontrast (D), late arterial phase (E), and portal venous phase (F) show nodular arterial enhancement and washout (arrows) of the lipiodol-defect area. The lesion was considered as viable tumor through both LI-RADS and mRECIST. Based on pathology examination, the lesion was diagnosed as HCC with 70% necrosis.

Figure 4.

A 52-year old man with hepatocellular carcinoma (HCC) who underwent transarterial chemoembolization (TACE). Post-TACE axial CT images obtained at precontrast (A) and the late arterial phase (B) demonstrate compact lipiodol uptake without residual arterial enhancing portion. Axial T1-weighted MR image at late arterial phase (D) shows remaining arterial enhancement (arrow) compared with that of precontrast scan (C). The lesion was categorized as nonviable tumor on CT, but viable tumor on MRI using both LI-RADS v2017 treatment response algorithm, and mRECIST. Based on pathology examination, the lesion was diagnosed as HCC with 80% necrosis.