Incidental pancreatic cysts: Natural history and diagnostic accuracy of a limited serial pancreatic cyst MRI protocol

Abstract

Objectives: To examine the natural history of incidentally detected pancreatic cysts and whether a simplified MRI protocol without gadolinium is adequate for lesion follow-up. Methods: Over a 10-year period, 301-patients with asymptomatic pancreatic cysts underwent follow-up (45 months±30). The magnetic resonance imaging (MRI) protocol included axial, coronal T2-weighted images, MR cholangiopancreatographic and fat suppressed T1-weighted sequences before and after gadolinium. Three radiologists independently reviewed the initial MRI, the follow-up studies using first only unenhanced images, then secondly gadolinium-enhanced-sequences. Lesion changes during follow-up were recorded and the added value of gadolinium-enhanced sequences was determined by classifying the lesions into risk categories. Results: Three hundred and one patients (1,174 cysts) constituted the study population. Only 35/301 patients (12 %) showed significant lesion change on follow-up. Using multivariate analysis the only independent factor of lesion growth (OR=2.4; 95 % CI, 1.7-3.3; P<0.001) and mural nodule development (OR=1.9; 95 % CI, 1.1-3.4, P=0.03) during follow-up was initial lesion size. No patient with a lesion initial size less than 2 cm developed cancer during follow-up. Intra-observer agreement with and without gadolinium enhancement ranged from 0.86 to 0.97. After consensus review of discordant cases, gadolinium-enhanced sequences demonstrated no added value. Conclusion: Most incidental pancreatic cystic lesions did not demonstrate change during follow-up. The addition of gadolinium-enhanced-sequences had no added-value for risk assignment on serial follow-up. Key points: • Significant growth of pancreatic cysts occurred in a minority of patients only. • No lesion <2 cm demonstrated any change during the first year of follow-up. • Intra-observer agreement between MR pancreatic protocols with and without gadolinium was excellent. • Gadolinium application had limited value for follow-up of asymptomatic pancreatic cystic lesions. © 2014 European Society of Radiology.