The Role of Functional MR Imaging in the Assessment of Tumor Response after Chemoembolization in Patients with Hepatocellular Carcinoma

Abstract

To assess treatment response of hepatocellular carcinoma (HCC) after transarterial chemoembolization (TACE) with use of diffusion and dynamic contrast medium-enhanced magnetic resonance (MR) imaging. MR imaging studies before and after TACE in 38 patients with HCC (33 male patients and five female patients) were evaluated. Diffusion and dynamic contrast medium-enhanced MR imaging was performed on a 1.5-T unit. The imaging protocol included T2-weighted fast spin-echo, breath-hold diffusion-weighted echoplanar, and breath-hold unenhanced and contrast medium-enhanced T1-weighted three-dimensional fat-saturation gradient-recalled echo imaging in the arterial and portal venous phases. Tumor size, percent enhancement, and apparent diffusion coefficient (ADC) values were recorded before and after treatment. Survival analysis was also performed. The study included 38 lesions with a mean diameter of 8.0 cm. Mean reduction in tumor diameter was 8 mm after treatment (t test; P = .0005), which did not fulfill Response Evaluation Criteria in Solid Tumors for complete or partial response. Reduction in tumor enhancement in the arterial (30%) and venous (47%) phases was statistically significant (signed-rank test; P = .0003 and P < 0.00005, respectively). Tumor ADC value increased from 0.0015 mm(2)/sec to 0.0018 mm(2)/sec after treatment (t test; P = .026), whereas the ADC values for the liver, spleen, and muscle remained unchanged. Median patient survival was 19 months. After TACE, tumors demonstrated decreased size and enhancement with increases in ADC values. In this cohort, diffusion and dynamic contrast medium-enhanced MR imaging parameters were significantly altered after TACE, and these could be useful tools in the assessment of tumor response.