Apparent diffusion coefficient reproducibility of the pancreas measured at different MR scanners using diffusion-weighted imaging

Abstract

Purpose: To evaluate the reproducibility of the pancreatic apparent diffusion coefficient (ADC) measured at different MR scanners. Materials and Methods: Twenty-four healthy volunteers underwent three consecutive diffusion-weighted imaging (DWI) at a GE 1.5 Tesla (T), a Siemens 1.5T and a Philips 3.0T (session 1), and imaged again using the same protocol at the same GE 1.5T (session 2) 12 days later. The ADC values of pancreas were measured at all three MR scanners. Paired-sample t-test and the Bland-Altman method were used for ADC data analysis. Results: The individual mean ADC values of pancreatic head, body, and tail (in 10∼3mm2/s) measured at GE 1.5T (2.24, 2.01, 1.88 for observer 1 and 2.23, 2.00, 1.92 for observer 2) and Siemens 1.5T (2.24, 2.04, 1.84 for observer 1 and 2.20, 1.98, 1.84 for observer 2) were significantly higher than those at Philips 3.0T (2.06, 1.80, 1.56 for observer 1 and 2.02, 1.79, 1.60 for observer 2) (P = 0.000-0.008). There was no significant difference of ADC values either between GE 1.5T and Siemens 1.5T (P = 0.115-0.966), or between imaging session 1 and 2 at GE 1.5T (P = 0.072-0.938). The range of mean difference ± limits of agreement (in 10∼3mm2/s) was -0.07-0.04 ± 0.39-0.53 between two 1.5T scanners, and -0.04-0.04 ± 0.24-0.47 between two imaging sessions at GE 1.5T. Conclusion: The measured ADC values of pancreas are affected by the field strength of scanner, but show good reproducibility between different MR systems with same field strength and at the same MR system over time.