Assessment of exocrine pancreatic function by secretin stimulated diffusion weighted imaging in healthy adult

Abstract

Objective To characterize and quantify exocrine pancreatic function by secretin stimulated diffusion weighted imaging (DWI) in healthy subjects. Methods The present study includes 20 health volunteers composed of 13 male and 7 female with a median age of (38±9) years and median BMI of (22.89±2.95)kg/m2. All subjects underwent MR imaging at 3.0 T device (Signa EXCITE, GE Healthcare). Axial T1 and T2 weighted sequences and the diffusion weighted sequence was acquired prior to administration of secretin (0 min) and 1, 3, 5, 7, 9, and 11 min after administration of secretin. A bolus of secretin was injected intravenously at a dose of 1 ml/kg body weight. The changes of pancreatic duct, baseline and peak apparent diffusion coeffcient (ADCs) values of pancreatic head, body and tail, and the percentage increase over the baseline ADCs, and time to peak ADCs were measured by the two radiologists. The feces elastase 1 (FE 1) test was used to determine the pancreatic exocrine reserve of all subjects. The comparisons of the two radiologists on the ADC measurements were determined by t test. Inter-group differences of ADC of pancreatic head, body and tail before administration of secretin, after administration of secretin, were compared each of the segments using multivariate analysis of variance (ANOVA). The correlation between FE 1 and the peak ADCs was analyzed by using Pearson's correlation test. Results There were no statistically significant differences of all ADCs between the two radiologists. The baseline ADCs of the 20 healthy subjects before administration of secretin was (1.60±0.21)×10-3 mm2/s, and the peak ADC was (2.70±0.25)×10-3mm2/s, which increased by (72±25)%, the time to peak ADCs was (2.97±0.88)min, then it gradually decreased to near baseline value before administration of secretin. The ADCs of pancreatic head, body and tail at 0, 1, 3, 5, 7, 9, 11 min after administration of secretin were statistically significant (P=0.0001), but at each time point, the difference among ADCs of pancreatic head, body and tail was not statistically significant. The mean FE 1 of 20 healthy subjects was (537.2±80.17) μg/g (range 341.2~673.2 μg/g). A positive linear correlation was found between the mean peak ADCs after administration of secretin and FE 1 (r=0.87, P=0.0001). Conclusions Secretin stimulated DWI can reflect the exocrine pancreatic function in healthy adults. Key words: Secretin; Diffusion magnetic resonance imaging; Pancreatic function tests