Does PET with CT Have Clinical Utility in the Management of Patients with Intraductal Papillary Mucinous Neoplasm?

Abstract

Background: Intraductal papillary mucinous neoplasms (IPMNs) are well-established pancreatic precancerous lesions. Indications for resection are outlined in the 2012 International Consensus Guidelines (ICG). Because of the low specificity of the ICG, many patients will undergo potentially unnecessary surgery for nonmalignant IPMNs. Several retrospective studies have reported that positron emission tomography (PET) with CT (PET/CT) is highly sensitive and specific in detecting malignant IPMNs. We hypothesized that PET/CT complements the ICG in identification of malignant IPMNs.

Study design: From 2009 to 2013, patients with a suspected clinical or cytopathologic diagnosis of IPMN were prospectively enrolled in a clinical trial at a single center. Results of preoperative PET/CT on determination of IPMN malignancy (ie, high-grade dysplastic and invasive) was compared with surgical pathology. PET/CT uptake was considered increased if the standardized uptake value was ≥3.

Results: Of the 67 patients enrolled, 50 patients met all inclusion criteria. Increased PET/CT uptake was associated with significantly more malignant and invasive IPMNs (80% vs 13%; p < 0.0001 and 40% vs 3%; p = 0.004). When patients were divided into branch duct and main duct IPMNs, increased PET/CT uptake was also associated with more malignancy (60% vs 0%; p = 0.006 for branch duct IPMN and 100% vs 23%; p = 0.003 for main duct IPMN). Patients with ICG criteria (eg, worrisome features and high-risk stigmata) and increased PET/CT uptake had more malignant and invasive IPMNs than patients with ICG criteria, but no increased uptake (78% vs 17%; p = 0.001 and 33% vs 3%; p = 0.03). The sensitivity and specificity of the ICG criteria for detecting malignancy were 92% and 27%, respectively, and PET/CT was less sensitive (62%) but more specific (95%). When PET/CT was added to ICG criteria, the association resulted in 78% sensitivity and 100% specificity.

Conclusions: The addition of PET/CT to preoperative workup improves the performance of the ICG for predicting malignant risk in patients with IPMN.