Variability in measurements of pancreatic cyst size among EUS, CT, and magnetic resonance imaging modalities

BackgroundCyst size is an important factor in the management of pancreatic cysts, both in predicting the need for surgery and the frequency of follow-up.ObjectiveTo determine agreement and precision of EUS, CT, and magnetic resonance imaging (MRI) modalities in the evaluation of pancreatic cyst diameter.DesignRetrospective chart review.SettingTertiary-care center, January 2000 to June 2009.PatientsThis study involved 175 patients presenting for EUS evaluation of pancreatic cysts, with size measured by at least two of the aforementioned imaging studies within a 90-day period.Main Outcome MeasurementsLargest cyst diameter from EUS, CT, MRI/MRCP, and surgical pathology.ResultsA total of 175 patients underwent EUS. Seventy-three had CT plus EUS, 33 had MRI/MRCP plus EUS, 23 had MRI/MRCP plus CT, and 15 had all imaging studies, occurring within 90 days of each other. Median size differences between studies: EUS and CT (ie, absolute value of size determined by EUS minus size determined by CT) = 4 mm (range 0-25 mm), EUS and MRI = 4 mm (range 0-17 mm), CT and MRI = 3 mm (range 2-20 mm). Median size differences for surgical pathology specimens compared with results of 12 EUS, 13 CT, and 8 MRI/MRCP studies were as follows: EUS and pathology = 9.5 mm (range 0-20 mm), CT and pathology = 5 mm (range 0-21 mm), MRI and pathology = 5.5 mm (range 2-44 mm).LimitationsInterobserver variability and small sample of surgical pathology cysts.ConclusionThere is considerable variation in size estimates of pancreatic cysts by different imaging modalities, which practitioners should take into account when making management decisions. Use of a single imaging modality is recommended during follow-up. The precision of imaging studies for measuring pancreatic cysts must be prospectively defined if change in size is to be reliably used for clinical management.