Islet Cell Liver Metastases: Assessment of Volumetric Early Response with Functional MR Imaging after Transarterial Chemoembolization

Purpose: To assess early response to transarterial chemoembolization by using volumetric functional magnetic resonance (MR) imaging in patients with islet cell liver metastases (ICLMs). Materials and Methods: This retrospective institutional review board-approved HIPAA-compliant study included 215 ICLMs in 26 patients (15 men, 11 women; mean age, 59.7 years; age range, 37-79 years). Volumetric measurements were performed by an experienced radiologist on diffusion-weighted and contrast material-enhanced MR images at baseline and 1-month follow-up. Measurements included mean change (three-dimensional [3D] mean apparent diffusion coefficient [ADC], 3D mean enhancement) and percentage of tumor with change above a predetermined threshold (3D threshold ADC, 3D threshold enhancement). Response by volumetric measurements at 1-month follow-up was compared with Response Evaluation Criteria in Solid Tumors (RECIST) at 6-month follow-up. Lesions that had complete or partial response were considered responders, while those with stable or progressive disease were considered nonresponders. Statistical analysis included the t test, receiver operating characteristic (ROC) curve analysis, and logistic regression analysis. Results: RECIST criteria at 6-month follow-up indicated 78 (36.3%) lesions responded, while 137 (63.7%) did not. The increase in 3D mean ADC was significantly higher in responders than in nonresponders (median, 26.2% vs 10.9%; P < .001). The 3D threshold ADC was 71.1% in responders and 47.6% in nonresponders (P < .001). Decrease in 3D mean arterial enhancement (AE) was significantly higher in responders than in nonresponders (median, 40.5% vs 18.0%; P < .001). Decrease in 3D mean venous enhancement (VE) was significantly higher in responders than in nonresponders (median, 28.0% vs 10.0%; P < .001). The 3D threshold VE and 3D threshold AE did not differ between responders and nonresponders. In unadjusted logistic regression analyses, 3D mean ADC and 3D threshold ADC had the highest odds ratio (1.02 and 1.03, respectively) and the largest area under the ROC curve (0.698 and 0.695, respectively). Conclusion: Volumetric functional MR imaging could be used to predict early response of hepatic ICLMs to therapy and to distinguish between responders and nonresponders. (C) RSNA, 2012