Diffusion Tensor Imaging
Study of mild traumatic brain injury (mTBI) in humans
In a DTI study of traumatic brain injury patients, focal axonal damage is observed via comparison between controls and patients. This imposes a unique requirement for tractography after renormalization of the brain into standard space. The conventional renormalization process introduces distortion into directional information associated with DTI data, such as eigenvectors. We implemented a Preservation of Principal Direction (PPD) Algorithm to ensure accuracy of the fiber tractograph after image registration and renormalization.
Registration effect on fiber tractograph. Images in the first row are for the left and right cingulum, from DTI data sets with PPD algorithm applied. Images in the second row are the same tracts from DTI data sets without PPD algorithm applied. Disturbances due to registration result in broken cingulums. PPD algorithm effectively removes these disturbances.
Quantification of DTI indices and tractography
DTI (diffusion tensor imaging) with stimulated echo acquisition method (STEAM): improved SNR and fiber tracts compared with the conventional DTI with the spin echo (SE) acquisition when scanning the short T2 skeletal muscles, as shown in Figure 1.
fig. Figure 1: STEAM DTI (a) generated more abundant and extended muscle fiber tracts than the conventional SE DTI (b) did.
Correction of susceptibility artifacts in DTI and fiber tracks. The upper row is the original distorted EPI image; the bottom row is after correction. Phase encoding direction is in AP. The lost tissue of frontal lobe is mostly recovered.
