Intravoxel incoherent motion MRI for monitoring the therapeutic response of hepatocellular carcinoma to sorafenib treatment in mouse xenograft tumor models.

Background With the introduction of targeted therapies, there has been a growing need for non-invasive imaging methods which accurately evaluate therapeutic effects and overcome the limitations of tumor size-based therapeutic response assessments. Purpose To assess diagnostic values of intra-voxel incoherent motion (IVIM) imaging in evaluating therapeutic effects of sorafenib on hepatocellular carcinoma (HCC) using mouse xenograft model. Material and Methods Twenty-four mice bearing Huh-7 were divided into a control group and two treatment groups received sorafenib doses of 5 mg/kg (5 mg-Tx) or 30 mg/kg (30 mg-Tx). IVIM imaging was performed using 10 b-values (0-900 s/mm(2)). The apparent diffusion coefficient (ADC), diffusion coefficient ( D), and perfusion fraction ( f) were measured for whole tumors and tumor periphery. Changes between baseline and post-treatment parameters ( Δ ADC, Δ D, and Δ f) were calculated, and these parameters were compared with microvessel density (MVD) and area of tumor cell death. Results The post-treatment f and Δ f for tumor periphery were significantly higher in control group, followed by 5 mg-Tx and 30 mg-Tx ( P < 0.001). MVD showed significant positive correlation with post-treatment f ( r = 0.584, P = 0.003) and negative correlation with D ( r = -0.495, P = 0.014) for tumor periphery, while no parameter showed significant correlation with area of tumor cell death. Conclusion The f is significantly correlated with MVD of HCC, and could potentially be used to evaluate the anti-angiogenic effects of sorafenib.