Radiologic-Pathologic Analysis of Contrast-enhanced and Diffusion-weighted MR Imaging in Patients with HCC after TACE: Diagnostic Accuracy of 3D Quantitative Image Analysis

Purpose: To evaluate the diagnostic performance of three-dimensional (3D) quantitative enhancement-based and diffusion-weighted volumetric magnetic resonance (MR) imaging assessment of hepatocellular carcinoma (HCC) lesions in determining the extent of pathologic tumor necrosis after transarterial chemoembolization (TACE). Materials and Methods: This institutional review board-approved retrospective study included 17 patients with HCC who underwent TACE before surgery. Semiautomatic 3D volumetric segmentation of target lesions was performed at the last MR examination before orthotopic liver transplantation or surgical resection. The amount of necrotic tumor tissue on contrast material-enhanced arterial phase MR images and the amount of diffusion-restricted tumor tissue on apparent diffusion coefficient (ADC) maps were expressed as a percentage of the total tumor volume. Visual assessment of the extent of tumor necrosis and tumor response according to European Association for the Study of the Liver (EASL) criteria was performed. Pathologic tumor necrosis was quantified by using slide-byslide segmentation. Correlation analysis was performed to evaluate the predictive values of the radiologic techniques. Results: At histopathologic examination, the mean percentage of tumor necrosis was 70% (range, 10%-100%). Both 3D quantitative techniques demonstrated a strong correlation with tumor necrosis at pathologic examination (R-2 = 0.9657 and R-2 = 0.9662 for quantitative EASL and quantitative ADC, respectively) and a strong intermethod agreement (R2 = 0.9585). Both methods showed a significantly lower discrepancy with pathologically measured necrosis (residual standard error [RSE] = 6.38 and 6.33 for quantitative EASL and quantitative ADC, respectively), when compared with non-3D techniques (RSE = 12.18 for visual assessment). Conclusion: This radiologic-pathologic correlation study demonstrates the diagnostic accuracy of 3D quantitative MR imaging techniques in identifying pathologically measured tumor necrosis in HCC lesions treated with TACE. (C) RSNA, 2014.