Biomechanical phase angle as proxy to quantify the presence of microvascular invasion in hepatocellular carcinoma

Motivation: In hepatocellular carcinoma (HCC), microvascular invasion (MVI), an indicator for tumor aggressiveness, is identified typically through post-resection pathology examination. Currently, non-invasive methods for assessing tumor aggressiveness are lacking. Goal(s): Our objective is to discover a non-invasive imaging biomarker for evaluating the presence/absence of MVI. Approach: The alterations induced by the tumor, such as MVI, can modify the tissue architecture and, consequently, its mechanical properties. Magnetic resonance elastography at 40Hz was performed in 44 HCC patients who had liver resection. Results: Peritumoral tissue phase angle accurately distinguish patients with/without MVI, indicative for aggressiveness. These results correlate with higher tumor differentiation in patients without MVI. Impact: This clinical study introduces the phase angle as a new biomarker for gauging HCC aggressiveness whereby enabling patient stratification.