MR elastography of hepatocellular carcinoma: Correlation of tumor stiffness with histopathology features—Preliminary findings

Purpose To determine if tumor stiffness by MR Elastography (MRE) is associated with hepatocellular carcinoma (HCC) pathologic features. Material and methods A retrospective review was undertaken of all patients with pathologically confirmed HCC who underwent MRE prior to loco-regional therapy, surgical resection or transplant between 1/1/2007 to 12/31/2015. An independent observer measured tumor stiffness (kilopascals, kPa) by drawing regions of interest (ROI) covering the HCC and in the case of HCCs with non-enhancing/necrotic components, only the solid portion was included in the ROI. HCC tumor grade (WHO criteria), vascular invasion and tumor encapsulation were assessed from retrievable pathology specimens by an expert hepatobiliary pathologist. Tumor stiffness was compared by tumor grade, size, presence of capsule and vascular invasion using Student's t-test (or Exact Mann-Whitney test). Results 21 patients were identified who had pathologically confirmed HCCs and tumor MRE data. 17 patients (81.0%) had underlying chronic liver disease. The mean ± SD tumor size (cm) was 5.3 ± 3.9 cm. The mean ± SD tumor stiffness was 5.9 ± 1.4 kPa. Tumors were graded as well differentiated (N = 2), moderately differentiated (N = 11) and poorly differentiated (N = 8). There was a trend toward increased tumor stiffness in well/moderately differentiated HCCs (6.5 ± 1.2 kPa; N = 13) compared to poorly differentiated HCCs (4.9 ± 1.2 kPa; N = 8) (p < 0.01). There was no significant correlation between tumor stiffness and liver stiffness or tumor size. There was no significant difference in tumor stiffness by presence or etiology of chronic liver disease, vascular invasion or tumor encapsulation. Conclusion Preliminary data suggest that tumor stiffness by MRE may be able to differentiate HCC tumor grade.