Assessment of Metastatic Breast Cancer Response to Chemoembolization with Contrast Agent-enhanced and Diffusion-weighted MR Imaging

Purpose: To assess the value of functional magnetic resonance (MR) imaging in the evaluation of early tumor response after transarterial chemoembolization (TACE) for metastatic breast cancer and to compare tumor response based on functional MR imaging versus traditional assessment based on iodized oil deposition, tumor size, and tumor enhancement. Materials and Methods: For 14 patients with metastatic breast cancer, MR imaging studies before and after TACE were evaluated. Diffusion and contrast medium-enhanced MR imaging was performed on a 1.5-T unit. Parameters evaluated included change in tumor size, enhancement, and apparent diffusion coefficient (ADC) values. Median survival was also calculated in the entire cohort. Results: A total number of 27 lesions were evaluated, with a mean diameter of 5.5 cm. Although mean tumor size decreased by 18% after treatment, no tumors met the Response Evaluation Criteria In Solid Tumors (RECIST) for complete response (ie, complete disappearance of target lesions) and only seven of 27 met RECIST for partial response (ie, >30% decrease in target lesion size). After treatment, decrease of tumor enhancement in the arterial (32%) and portal venous (39%) phases was statistically significant (P < .0001). Mean tumor ADC increased by 27% (P < .0001) after TACE, whereas ADC remained unchanged in nontumorous liver, spleen, and kidney. Median survival was 25 months for the entire cohort. Conclusion: In patients with breast cancer and liver metastases who were treated with TACE, although changes in tumor size were small, significant early changes in the treated lesions occurred on contrast medium-enhanced and functional MR imaging. These include decrease in tumor enhancement and increase in tumor ADC value, which suggest increasing tumor necrosis and cell death.