Pancreatic CT density is an optimal imaging biomarker for earlier detection of malignancy in the pancreas with intraductal papillary mucinous neoplasm.

BACKGROUND: Intraductal papillary mucinous neoplasms (IPMNs) are typically detected as incidental findings by computed tomography (CT); however, the conventional surveillance is not valid for the early detection of concomitant pancreatic cancer. The pancreas of IPMN is often accompanied by fatty infiltration in the parenchyma, and pancreatic fatty infiltration could be evaluated by pancreatic CT density (pancreatic index, PI). We aimed to investigate whether PI could be an imaging biomarker for the early prediction of malignancies in the pancreas with IPMN. METHODS: Two different cohorts were investigated. (Investigation cohort): A total of 1137 patients with initially low-risk IPMN were compensated by initial IPMN findings, and 2 groups (malignancy/possible benign, 50 cases each) were investigated for yearly changes in PI and for the cutoff value of PI indicating the development of malignancies. (Validation cohort): To validate the cutoff value, 256 patients radiologically suspected of having IPMNs were investigated. RESULTS: (Investigation-cohort): The malignancy group showed a gradual decrease in PI every year, and PI significantly differed among the 2 groups 1 year prior to the last investigation. The cutoff value of PI was set at 0.65. (Validation-cohort): A total of 55% of the patients with a PI below the cutoff value had malignancy in the pancreas, including concomitant pancreatic cancer, and the cutoff value was the most significant risk factors for the development of malignancies in the pancreas compared to the conventional risk factors for IPMN. CONCLUSIONS: Decreasing PI would be an optimal imaging biomarker for earlier detection of malignancies in the pancreas with IPMN.

Imaging morphological changes of intraductal papillary mucinous neoplasm of the pancreas was associated with its malignant transformation but not with development of pancreatic ductal adenocarcinoma.

BACKGROUND/OBJECTIVE: A considerable number of branch duct intraductal papillary mucinous neoplasm (BD-IPMN) developed not infrequently pancreatic malignancy, either as part of IPMN (malignant IPMN) or as concomitant pancreatic ductal adenocarcinoma (PDAC). To date, imaging morphological changes predicting occurrence of malignancy in BD-IPMN are not well-investigated. This study aimed to evaluate the relationships between occurrence of malignancy in BD-IPMN and imaging morphological changes of the tumors observed during follow-up. METHODS: 515 BD-IPMN patients with mural nodule <10 mm and negative cytology were included. 19 patients developed malignant IPMN and 8 patients developed concomitant PDAC during mean follow-up of 4.7 years. The following imaging morphological features were assessed: cyst/main pancreatic duct (MPD) diameter, occurrence of additional cyst/mural nodule. RESULTS: Growth rate of cyst/MPD diameter were significantly larger in patients who developed malignant IPMN compared to those in patients whose IPMN remained benign (p = 0.013, p = 0.01). Occurrence of additional cyst/mural nodule were more frequently observed in patients who developed malignant IPMN (p = 0.009, p = 0.04). In contrast, none of the factors associated with imaging morphological changes of IPMN were shown to be significantly different between patients who developed concomitant PDAC and patients whose IPMN remained benign. Growth rate of MPD diameter and occurrence of additional cyst were independent factors associated with development of malignant IPMN (odds ratio 21.5, and 5.62, respectively). CONCLUSIONS: Imaging morphological changes of IPMN, such as growth rate of MPD diameter and occurrence of additional cyst, could be indicators for development of malignant IPMN, but not for development of concomitant PDAC.