Abstract 2586: Heterogeneous enhancement pattern of Gd-EOB-DTPA-enhanced MRI predicts vessels encapsulating tumor clusters (VETC)-positive hepatocellular carcinoma

Abstract Background: Vessels encapsulating tumor clusters (VETC) pattern is known as a distinct hepatocellular carcinoma (HCC) vascularization that correlates with angiogenic status, lower lymphocytic infiltration, and higher recurrence rates. Despite the molecular and clinical significance of VETC+ HCC, its characteristics on radiological imaging have not been clearly elucidated. We aimed to characterize VETC+ HCC on gadolinium-ethoxybenzyl-diethylene-triamine-pentaacetic acid-enhanced MR imaging (EOB-MRI) and provide pathological evidence. Method: We studied 204 surgically resected HCCs with preoperative EOB-MRI. VETC+ HCC was defined as ≥1% VETC occupied area evaluated by CD34 immunostaining. The visual pattern classification of the arterial and hepatobiliary phase images is shown in Table 1. To investigate the relationships between imaging patterns and VETC+ HCC, we evaluated immunohistochemical expression of h-caldesmon+ arterial vessel density (AVD) and OATP1B3. Result: In the arterial phase, VETC+ HCCs showed heterogeneous hypervascular pattern and homogeneous hypovascular pattern. Accordingly, VETC+ HCCs had lower AVD than VETC− HCCs, as well, VETC regions had lower AVD than other regions within the same tumor. In the hepatobiliary phase, VETC+ HCCs were observed more frequently in heterogeneous hyperintense pattern (36%) compared to homogeneous hyperintense pattern (5%). Hyperintensity in the hepatobiliary phase was correlated with high expression of OATP1B3. Among tumors with high OATP1B3 expression, VETC regions showed decreased expression of OATP1B3. Conclusion: VETC+ HCC showed reduced vascularity and heterogeneous hyperintensity in the hepatobiliary phase of EOB-MRI. These findings were explained by locally reduced AVD and downregulated OATP1B3 expression in the VETC regions. The potency to predict VETC+ HCCs by radiological findings could improve HCC treatment strategy. Relationship between enhancement patterns and VETC+ HCC in arterial and hepatobiliary phase Arterial phase Hypervascular/Homogeneous Hypervascular/Heterogeneous Hypovascular/Homogeneous Hypovascular/Heterogeneous Rim-like Number of tumors 68 103 8 15 11 VETC+ HCC (%) 6 (9%) 32 (31%) 3 (37%) 3 (20%) 1 (9%) Hepatobiliary phase Hyperintense/Homogeneous Hyperintense/Heterogeneous Hypointense/Homogeneous Hypointense/Heterogeneous Number of tumors 21 39 115 31 VETC+ HCC (%) 1 (5%) 14 (36%) 23 (20%) 8 (26%) Citation Format: Kosuke Matsuda, Akihisa Ueno, Junya Tsuzaki, Yutaka Kurebayashi, Ken Yamazaki, Masashi Tamura, Masahiro Jinzaki, Yuta Abe, Yasushi Hasegawa, Minoru Kitago, Michiie Sakamoto. Heterogeneous enhancement pattern of Gd-EOB-DTPA-enhanced MRI predicts vessels encapsulating tumor clusters (VETC) -positive hepatocellular carcinoma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 2586.