Intraductal Papillary Mucinous Neoplasms of the Pancreas: CT Patterns of Recurrence and Multiobserver Performance in Detecting Recurrent Neoplasm After Surgical Resection

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Abstract
OBJECTIVE. The purposes of our study were to describe the CT appearance of recurrent intraductal papillary mucinous neoplasms of the pancreas after surgical resection and estimate the performance of CT in detecting recurrent neoplasms. MATERIALS AND METHODS. A single unblinded reviewer characterized the presence and appearance of recurrent intraductal papillary mucinous neoplasms on 66 CT scans of 17 patients with proven recurrence, noting location and appearance of recurrent neoplasm. These results, described in this article, were summarized in tabular format and shown to three blinded observer. The observers then evaluated one postoperative CT examination from every patient at our institution who underwent surgical removal of intraductal papillary mucinous neoplasms (n = 45) for the presence or absence of local or distant recurrence. RESULTS. The unblinded reviewer found 11 cases of local recurrence. Extrapancreatic local recurrences tend to have solid components (5/6), tend to be located adjacent to the resection margin (5/6), and may exhibit vascular invasion (2/6). Intrapancreatic neoplasms are usually cystic (4/5). Nine patients had distant metastases. Prospective sensitivity for recurrent tumor ranged from 76% (13/17) to 94% (16/17). Sensitivity for local recurrence ranged from 55% (6/11) to 82% (9/11). Specificity ranged from 79% (22/28) to 96% (27/28). Interobserver agreement for predicting recurrence was moderate to substantial (κ = 0.51-0.65). CONCLUSION. Locally recurrent intraductal papillary mucinous neoplasms of the pancreas tend to be either extrapancreatic and solid at the resection margin or intrapancreatic and cystic. CT can detect most recurrent intraductal papillary mucinous neoplasms of the pancreas with moderate to substantial interobserver agreement.