Contrast-enhancement ratio on multiphase enhanced computed tomography predicts recurrence of pancreatic neuroendocrine tumor after curative resection

Background/Objective: No previous study has quantitatively investigated the degree of enhancement of pancreatic neuroendocrine tumors (pNETs) using a routine preoperative modality. The aim of this study was to evaluate the contrast-enhancement ratio (CER) of pNETs using multiphase enhanced CT and to assess the impact of the CER on disease recurrence after surgery. Methods: A retrospective study was performed using data from 47 consecutive patients with pNETs who had undergone curative surgery. The CER of the tumor was calculated by dividing the CT attenuation value obtained during the maximum-enhanced phase by that obtained during the pre-enhanced phase. A region of interest was placed in the largest tumor dimension plane so as to cover as much surface of the tumor as possible while avoiding adjacent normal structures, calcification, and necrotic areas of the tumor. Results: During a median follow-up period of 51 months (range, 1-132 months), a total of 4 patients (8.5%) developed disease recurrence. The median CER value was significantly lower for the patients with recurrence than for the patients without recurrence (2.9 vs. 4.3, P = 0.013). Univariate analyses showed that a CER <= 3.2 was significantly associated with disease recurrence (P < 0.001). All the patients with disease recurrence had tumors that were both large (>20 mm) and weakly enhanced (CER <= 3.2), whereas no recurrences were observed even in patients with tumors >20 mm when the CER was greater than 3.2. Conclusions: CER might be a useful predictor of disease recurrence in patients with pNETs. (C) 2016 IAP and EPC. Published by Elsevier B.V. All rights reserved.