title: Whole-body diffusion kurtosis imaging: initial experience on non-Gaussian diffusion in various organs.
abstract: BACKGROUND
  Diffusion kurtosis imaging (DKI) is based on a non-Gaussian diffusion model that should inherently better account for restricted water diffusion within the complex microstructure of most tissues than the conventional diffusion-weighted imaging (DWI), which presumes Gaussian distributed water molecule displacement probability. The aim of this investigation was to test the technical feasibility of in vivo whole-body DKI, probe for organ-specific differences, and compare whole-body DKI and DWI results.
  
  
  METHODS
  Eight healthy subjects underwent whole-body DWI on a clinical 3.0 T magnetic resonance imaging system. Echo-planar images in the axial orientation were acquired at b-values of 0, 150, 300, 500, and 800 mm²/s. Parametrical whole-body maps of the diffusion coefficient (D), the kurtosis (K), and the traditional apparent diffusion coefficient (ADC) were generated. Goodness of fit was compared between DKI and DWI fits using the sums of squared residuals. Data groups were tested for significant differences of the mean by paired Student t tests.
  
  
  RESULTS
  Good-quality parametrical whole-body maps of D, K, and ADC could be computed. Compared with ADC values, D values were significantly higher in the cerebral gray matter (by 30%) and white matter (27%), renal cortex (23%) and medulla (21%), spleen (101%), as well as erector spinae muscle (34%) (each P value <0.001). No significant differences between D and ADC were found in the cerebrospinal fluid (P = 0.08) and in the liver (P = 0.13). Curves of DKI fitted the measurement points significantly better than DWI curves did in most organs.
  
  
  CONCLUSIONS
  Whole-body DKI is technically feasible and may reflect tissue microstructure more meaningfully than whole-body DWI.
authors: From the *Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, and †Institute for Biomedical Engineering, University and Swiss Federal Institute of Technology Zurich, Zurich, Switzerland.
authors: Lukas
authors: L
authors: Filli
authors: Moritz
authors: M
authors: Wurnig
authors: Daniel
authors: D
authors: Nanz
authors: Roger
authors: R
authors: Luechinger
authors: David
authors: D
authors: Kenkel
authors: Andreas
authors: A
authors: Boss
mesh_terms: D000328:Adult; D001834:Body Water / Q000378:metabolism; D001921:Brain / Q000033:anatomy & histology; D002555:Cerebrospinal Fluid; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D017352:Echo-Planar Imaging / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008099:Liver / Q000033:anatomy & histology; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology; D012016:Reference Values; D015203:Reproducibility of Results; D013131:Spine / Q000033:anatomy & histology; D013154:Spleen / Q000033:anatomy & histology; D051598:Whole Body Imaging / Q000379:methods*; D055815:Young Adult