Comparison of Volume-Mode 2-Rotation kV-mA Switching Dual Energy Computer Tomography (CT) and of CT Subtraction Imaging With Magnetic Resonance Imaging for the Identification of Enhancing Septa and Mural Nodules in Cystic Pancreatic Lesions

With the rapid technological advancement, growth and widespread use of cross-sectional imaging, there has been increased detection of pancreatic cystic lesions (PCs). The reported incidence of pancreatic cysts varies widely, with some studies reporting incidental pancreatic cysts detected in 0.7-2.6 % of asymptomatic adults undergoing imaging. The incidence reportedly increases with age with a greater than 8% detection rate in those over age 80 years. The prevalence of a cystic pancreatic lesion in one autopsy series was as high as 24%. For MRI, the frequency of detection of a pancreatic cyst is significantly higher than that of CT, with a reported prevalence of 13-45 % for MRI. Consequently, there has been a significant increased number of MRs ordered for follow-up of these lesions. In our institution, more than 35 MR studies for assessment of PCs were performed each month in 2015. This represents greater than 5% of all abdominal/pelvic MR examinations, and this number appears to be growing. The impact on health care system - particularly on health care costs as well as MR waiting times for patients with other conditions - is significant. For instance, in our institution, the average waiting period in 2015 for an outpatient MR enterography for patients with Crohn's disease is over 6 months.

Recently, dual energy CT (DECT) has proven to be robust and clinically useful for many abdominal applications (including solid pancreatic masses). The investigators expect V2R kVmAS DECT and Subtraction imaging - two promising techniques which have scarcely been investigated in abdominal disease processes in the literature - to prove to be very useful for the characterization of pancreatic cysts and to demonstrate comparable diagnostic accuracy compared to MR

The aim of the study is to investigate whether optimized DECT and/or Subtraction imaging protocols allow for characterization of cystic pancreatic lesions (in particular, the presence of enhancing septa and mural nodules) with a diagnostic accuracy equivalent to or greater than MRI.

This is a prospective, single-institution study in patients who are being evaluated or followed for known pancreatic cystic lesions who are planned for a CT and MRI scan. All MRI scans performed during the study period will be monitored prospectively to identify consecutive patients undergoing MRI for assessment or follow-up of pancreatic cystic lesions and meeting the study inclusion/exclusion criteria.

Patients will be divided into two groups: