Isotropic diffusion-weighted and spiral-navigated interleaved EPI for routine imaging of acute stroke.
An interleaved echo-planar imaging (EPI) technique is presented for the rapid acquisition of isotropic diffusion-weighted images of stroke patients. Sixteen isotropic diffusion-weighted images at three b values are acquired in less than 3 min. A spiral navigator echo is used to measure the constant and linear phase shifts across the head in both the x and y directions which result from motion during the isotropic diffusion- sensitizing gradients. The measured k-space errors are corrected during a gridding reconstruction. The gridding kernel has a constant width in kx and a variable width in ky which eliminates variable data-density ghosts. The resulting isotropic diffusion-weighted images have excellent lesion-to-normal brain contrast, very good spatial resolution, and little sensitivity to susceptibility effects in the base of the brain. Examples of diffusion-weighted images and ADC maps from several stroke patients are shown.
Butts
K
K
Lucas MRS Imaging Center, Stanford, CA 94305-5488, USA.
Pauly
J
J
de Crespigny
A
A
Moseley
M
M
D000208:Acute Disease; D016477:Artifacts; D001921:Brain / Q000473:pathology*; D002561:Cerebrovascular Disorders / Q000175:diagnosis*; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D013997:Time Factors