Filip Szczepankiewicz1, 2, Alexander Leemans3, Pia Sundgren, 14, Ronnie Wirestam2, Freddy Sthlberg1, 2, Danielle van Westen, 14, Jimmy Ltt4
1Department of Diagnostic Radiology, Lund University, Lund, Sweden; 2Department of Medical Radiation Physics, Lund University, Lund, Sweden; 3University Medical Center Utrecht, Image Sciences Institute, Utrecht, Netherlands; 4Center for Medical Imaging and Physiology, Skne University Hospital, Lund, Sweden
Statistical power and variability analysis was performed using 20 sets of DKI data. The mean diffusivity (MD), fractional anisotropy (FA), mean kurtosis (MK) and radial kurtosis (RK) were determined in the cingulum, corpus callosum and corticospinal tract. Sample sizes required to detect a 10% difference with a power of 0.9 were calculated. Variability was divided into inter-subject biological differences and that arising from measurement noise. Minimum sample sizes varied across structures and metrics, but were approximately 15 for MD, FA and MK, and approximately 30 for RK. The inter-subject biological variability was the main contributor to total variability.