NAVIGATED DIFFUSION IMAGING OF NORMAL AND ISCHEMIC HUMAN BRAIN

The principal barrier to clinical application of diffusion-weighted MR imaging is the severe image degradation caused by patient motion, One way to compensate for motion effects is the use of a ''navigator echo '' phase correction scheme, In this work, a modification of this techn ique is introduced, in which the phase correction step is performed in the frequency domain (i.e., after the readout Fourier transform). Thi s significantly improves the robustness of the navigator echo approach and, when combined with cardiac gating, allows diagnostic quality dif fusion-weighted images of the brain to be routinely obtained on standa rd clinical scanner hardware, The technique was evaluated in phantom s tudies and in 23 humans (3 normal volunteers and 20 patients). Diffusi on anisotropy and apparent diffusion coefficient maps were generated f rom the image data and showed decreased apparent diffusion in acute st roke lesions and, in several cases, increased apparent diffusion in ch ronic stroke lesions.