Apparent Diffusion Coefficient Values for Neuroendocrine Liver Metastases

Rationale and Objectives We aimed to investigate whether there are any differences in apparent diffusion coefficient (ADC) values obtained from liver metastases due to gastroenteropancreatic neuroendocrine tumors (GEP-NET) and adenocarcinomas. Materials and Methods We included 54 patients with 167 liver metastases due to gastroenteropancreatic tumors. We divided the patients into two groups as liver metastases due to GEP-NETs (seven patients with 51 lesions, mean age: 48) and adenocarcinomas (47 patients with 116 lesions, mean age: 61.2). We used the independent samples t-test to compare the ADC and ADCmean values of the two groups and performed a receiver-operating characteristic analysis. Results ADC and ADCmean values were significantly lower in the GEP-NET group compared with the adenocarcinoma group. Receiver-operating characteristic curve analysis showed a significant difference for ADC and ADCmean values, and area under the curve values were 0.733 and 0.790, respectively. The cut-off values were 933x10-6 mm2/s for ADC and 801x10-6 mm2/s for ADCmean. Diagnostic accuracies of ADC (Sensitivity = 80.2, Specificity = 64.7, PPV = 83.8, NPV = 58.9) and ADCmean (Sensitivity = 63.8, Specificity = 82.4, PPV = 89.2, NPV = 50) were calculated in differentiating adenocarcinoma metastases from GEP-NET metastases. Conclusion The lower ADC and ADCmean values of liver metastases suggest GEP-NET rather than adenocarcinomas. ADC and ADCmean values obtained from liver metastases may be used to differentiate NETs from adenocarcinomas.