[Evaluation of intraductal papillary mucinous neoplasms of the pancreas on MDCT and MRI].

Objective: The purpose of our study was to evaluate the predictive factors of the presence of invasive carcinoma associated with intraductal papillary mucinous neoplasm (IPMN) of the pancreas on MDCT and MRI.

Methods: Preoperative MDCT or/and MRI of 27 consecutive patients (19 men, 8 women, mean age 61.3 years) who had undergone surgical resection and had a pathological diagnosis of IPMN were retrospectively assessed. The type of ductal involvement, solid appearance of the lesion, location, tumor size of branch duct type and combined type lesions, maximum diameter of the tumor, caliber of the main pancreatic duct and the extent of the common bile duct dilatation were assessed on CT and MRI and correlated with the pathological findings of the invasive carcinoma. Two abdominal radiologists reviewed all the images, and when discrepancies of the findings were found, the consensus was reached by discussion.

Results: Pathological analysis revealed carcinoma in situ in two patients and invasive carcinoma in 19 patients arising from the IPMN. The type of ductal involvement (P = 0.038), a solid mass (P = 0.003) and the common bile duct dilatation ( ≥ 15 mm, P = 0.004) were correlated with the presence of associated invasive carcinoma. For the finding of solid and cystic mass in predicting invasive IPMN, the sensitivity was 66.7% (8/12) and specificity was 100.0% (8/8), and for bile duct diameter ≥ 15 mm, the sensitivity was 47.4% (9/19) and specificity was 100.0% (8/8). However, no association was found between the location of the lesion and associated invasive carcinoma. The caliber of the main pancreatic duct of patients with associated invasive carcinoma was significantly larger than that in the cases without invasive carcinoma (8.07 ± 2.23 mm vs. 4.86 ± 1.86 mm, P = 0.002). When using the main pancreatic duct dilatation ≥ 4 mm as the threshold, the sensitivity and specificity in predicting invasive IPMN were 94.7% (18/19) and 37.5% (3/8), respectively. For the branch duct type and combined type, the size of the tumor with associated invasive carcinoma was significantly larger than these without invasive carcinoma (41.35 ± 12.58) mm vs. (23.76 ± 8.06) mm (P = 0.003). When the maximum diameter was ≥ 40 mm, the sensitivity and specificity in predicting invasive IPMN were 50.0% (6/12) and 87.5% (7/8), respectively.

Conclusions: The findings of CT and MRI are helpful to predict invasive carcinoma associated with IPMN, which may play an important role in the preoperative evaluation, surgical planning and predicting the prognosis of IPMN.