Comparative study of 3D MR elastography and intravoxel incoherent motion for the evaluation of hepatocellular carcinoma grade

Background and aims: Noninvasive preoperative radiologic prediction of histologic grade—a key prognostic factor—is invaluable. We aim to compare the diagnostic values of 3D magnetic resonance elastography (MRE), intravoxel incoherent motion (IVIM), and conventional contrast-enhanced magnetic resonance imaging (cMRI) in predicting the histologic grade of hepatocellular carcinoma (HCC). Methods: This institutional review board-approved retrospective study included patients who underwent MRI between December 2014 and October 2021. Sixty-eight patients with pathologically confirmed HCCs who underwent MRE, IVIM, and cMRI imaging were included in the analysis. Two radiologists measured HCC stiffness volumetrically and over a single slice, and also measured apparent diffusion coefficient (ADC), IVIM-derived parameters, and enhancement ratio (ER) on arterial phase images via cMRI. Student’s t-test or the Mann–Whitney U test was used for group comparisons. Receiver operating characteristic (ROC) curve analyses were performed to evaluate the diagnostic performance. Results: Histologically, fifty-three (78%) patients had well-differentiated or moderately differentiated HCCs, and fifteen (22%) patients had poorly differentiated HCCs. Both the volumetric stiffness and single-ROI tumor stiffness were significantly elevated in the poorly differentiated HCC group (P < 0.001, P = 0.001), and the volumetric stiffness was a better measurement of stiffness because it had a higher ROC curve value (0.816). However, the ADC, the true diffusion coefficient (D), the pseudodiffusion coefficient (D∗), the pseudodiffusion fraction (f), and ER during the arterial phases on cMRI were not significantly different between the two groups (P = 0.309, 0.187, 0.440, 0.350, and 0.714, respectively). Conclusions: Stiffness measured with 3D MRE may be useful for noninvasively predicting HCC histologic grade, and the volumetric measuring method achieved the highest ROC curve value, outperforming single-ROI HCC stiffness, IVIM parameters, and arterial-phase ER on cMRI.