Assessment of structural heterogeneity and its correlation with early recurrence in hepatocellular carcinoma by diffusion weighted imaging based virtual MR elastography

Background：The mechanical characteristics of tumors are closely related to their invasive growth, metastasis and diffusion. Virtual MR elastography(vMRE), which is based on diffusion weighted imaging (DWI), can quickly and reliably reflect the biomechanical properties of cancer without the need for invasive procedures. Aims: To explore the correlation between structural heterogeneity, early recurrence, and virtual shear modulus (m _diff ) of hepatocellular carcinoma (HCC) measured by vMRE. Materials: A total of 40 HCC patients were retrospectively collected. All patients underwent routine MR sequence and DWI. The m _diff value was estimated by DWI with lower b values (b =200 s/mm ² ) and higher b values (b =1500 s/mm ² ). The m _diff inside the tumor(m _diff-tumor ), at the tumor edge(m _diff-edge ), and around the tumor (within 1cm) (m _diff-around ) were measured, as well as the sum(m _diff-sum ) of the above parameters. T test was used to compare the differences between groups, and ROC curves were drawn to evaluate the diagnostic efficacy of vMRE. Kaplan-Meier curve, Log-rank test and Cox regression were used for survival analysis. Results: The m _diff-tumor , m _diff-edge , m _diff-sum of low differentiation (4.968 kPa, 4.553 kPa, 27.822 kPa) are higher than those of medium-high differentiation (3.554 kPa, 2.858 kPa, 18.762 kPa) (P <0.050). The m _diff-sum shows the highest diagnostic efficiency, with sensitivity, specificity, and AUC of 77.8%, 90.6%, and 0.823, respectively. There were no significant differences of m _diff-tumor , m _diff-edge , m _diff-around , m _diff-sum in vascular invasion, hemorrhage, necrosis or size (P>0.050). Patients with m _diff-around greater than 5.060 kPa are at a higher risk of early recurrence (P=0.003), and the m _diff-around serves as an independent predictor of early recurrence (HR=0.155, 95%CI 0.031 ~ 0.770, P=0.023). Conclusion: vMRE can effectively differentiate the pathological grading of HCC, and the values around the tumor have certain early warning significance for the early recurrence of HCC.