Comparison and reproducibility of ADC measurements in breathhold, respiratory triggered, and free-breathing diffusion-weighted MR imaging of the liver

Abstract

Purpose: To compare and determine the reproducibility of apparent diffusion coefficient (ADC) measurements of the normal liver parenchyma in breathhold, respiratory triggered, and free-breathing diffusion-weighted magnetic resonance imaging (DWI). Materials and Methods: Eleven healthy volunteers underwent three series of DWI. Each DWI series consisted of one breathhold, one respiratory triggered, and two free-breathing (thick and thin slice acquisition) scans of the liver, at b-values of 0 and 500 s/mm2. ADCs of the liver parenchyma were compared by using nonparametric tests. Reproducibility was assessed by the Bland-Altman method. Results: Mean ADCs (in 10-3 mm2/sec) in respiratory triggered DWI (2.07-2.27) were significantly higher than mean ADCs in breathhold DWI (1.57-1.62), thick slice free-breathing DWI (1.62-1.65), and thin slice free-breathing DWI (1.57-1.66) (P < 0.005). Ranges of mean difference in ADC measurement ± limits of agreement between two scans were -0.02-0.05 ± 0.16-0.24 in breathhold DWI, -0.14-0.20 ± 0.59-0.60 in respiratory triggered DWI, -0.03-0.03 ± 0.20-0.29 in thick slice free-breathing DWI, and -0.01-0.09 ± 0.21-0.29 in thin slice free-breathing DWI. Conclusion: ADC measurements of the normal liver parenchyma in respiratory triggered DWI are significantly higher and less reproducible than in breathhold and free-breathing DWI. © 2008 Wiley-Liss, Inc.