Comparison of free‐breathing with navigator‐controlled acquisition regimes in abdominal diffusion‐weighted magnetic resonance images: Effect on ADC and IVIM statistics

Purpose To evaluate the effect on diffusion‐weighted image‐derived parameters in the apparent diffusion coefficient (ADC) and intra‐voxel incoherent motion (IVIM) models from choice of either free‐breathing or navigator‐controlled acquisition. Materials and Methods Imaging was performed with consent from healthy volunteers ( n  = 10) on a 1.5T Siemens Avanto scanner. Parameter‐matched free‐breathing and navigator‐controlled diffusion‐weighted images were acquired, without averaging in the console, for a total scan time of ∼10 minutes. Regions of interest were drawn for renal cortex, renal pyramid, whole kidney, liver, spleen, and paraspinal muscle. An ADC diffusion model for these regions was fitted for b‐values ≥ 250 s/mm 2 , using a Levenberg‐Marquardt algorithm, and an IVIM model was fitted for all images using a Bayesian method. Results ADC and IVIM parameters from the two acquisition regimes show no significant differences for the cohort; individual cases show occasional discrepancies, with outliers in parameter estimates arising more commonly from navigator‐controlled scans. The navigator‐controlled acquisitions showed, on average, a smaller range of movement for the kidneys (6.0 ± 1.4 vs. 10.0 ± 1.7 mm, P  = 0.03), but also a smaller number of averages collected (3.9 ± 0.1 vs. 5.5 ± 0.2, P  < 0.01) in the allocated time. Conclusion Navigator triggering offers no advantage in fitted diffusion parameters, whereas free‐breathing appears to offer greater confidence in fitted diffusion parameters, with fewer outliers, for matched acquisition periods. J. Magn. Reson. Imaging 2014;39:235–240. © 2013 Wiley Periodicals, Inc.