Visualization of neural tissue water compartments using biexponential diffusion tensor MRI

The apparent diffusion tensor (ADT) imaging method was extended to account for multiple diffusion components. A biexponential ADT imaging experiment w as used to obtain separate images of rapidly and slowly diffusing water fra ctions in excised rat spinal cord. The fast and slow component tensors were compared and found to exhibit similar gross features, such as fractional a nisotropy, in both white and gray matter. However, there were also some imp ortant differences, which are consistent with the different structures occu pying intracellular and extracellular spaces. Evidence supporting the assig nment of the two tensor components to extracellular and intracellular water fractions is provided by an NMR spectroscopic investigation of homogeneous samples of brain tissue. Magn Reson Med 45:580-587, 2001. (C) 2001 Wiley-L iss, Inc.