Diffusion-weighted magnetic resonance imaging for evaluating the histological degree of malignancy in patients with intraductal papillary mucinous neoplasm

Background The aim of this study was to evaluate the usefulness of high b‐value diffusion‐weighted magnetic resonance imaging (DWI) for evaluating the histological degree of malignancy in patients with intraductal papillary mucinous neoplasm (IPMN). Methods A total of 35 patients (mean age 68 ± 10 years, 23 males) who had undergone DWI before surgery were included in this study. Of these 35 patients, 13 had IPMN with low‐ or intermediate‐grade dysplasia, eight had IPMN with high‐grade dysplasia, and 14 had IPMN with an associated invasive carcinoma. We evaluated the positive signal rate on DWI and the apparent diffusion coefficient (ADC) value of each pathology. Results The positive signal rate on DWI of IPMN with low‐ or intermediate‐grade dysplasia, of IPMN with high‐grade dysplasia, and of IPMN with an associated invasive carcinoma were 0% (0/13), 38% (3/8), and 93% (13/14), respectively. The sensitivity, specificity, and accuracy for malignancy (IPMN with high‐grade dysplasia or IPMN with an associated invasive carcinoma) using DWI were 73%, 100%, and 83%, respectively. The mean ADC value of malignancy was significantly lower than that of benignity (P = 0.002). Conclusions Diffusion‐weighted magnetic resonance imaging, easily applicable in addition to conventional MRI, is considered an efficient modality for evaluating the histological degree of malignancy in patients with IPMN.