March 29, 2012 Leave a comment
HIGH DEFINITION FIBER TRACKING
This is the study of a man who was riding his ATV without wearing a helmet. CYCLISTS…wear a helmet at all times while riding your bike! The HDFT process uses data from MRI scanners which is then processed through algorithms to show a visualization of the brain along with the breaks along the “fiber tracts” which contains millions of neuronal connections. Traditional testing like CT scans and MRI’s only showed part of the story. After 3 weeks in a coma the patient still could not move his left side. For this particular patient, only the HDFT showed a lesion on the brain connected with his left-sided weakness.
This 32-year-old man sustained a severe TBI. Computed tomography and MRI revealed an area of hemorrhage in the basal ganglia with mass effect, but no specific information on the location of axonal injury could be obtained from these studies. Examinations of the patient at Week 3 and Week 8 after TBI revealed motor weaknesses of the left extremities. Four months postinjury, 257-direction diffusion spectrum imaging and HDFT analysis was performed to evaluate the degree of axonal damage in the motor pathway and quantify asymmetries in the left and right axonal pathways. High-definition fiber tracking was used to follow corticospinal and corona radiata pathways from the cortical surface to the midbrain and quantify projections from motor areas. Axonal damage was then localized by assessing the number of descending fibers at the level of the cortex, internal capsule, and midbrain. The motor deficit apparent in the clinical examinations correlated with the axonal losses visualized using HDFT. Fiber loss estimates at 4 months postinjury accurately predicted the nature of the motor deficits (severe, focal left-hand weakness) when other standard clinical imaging modalities did not. A repeat scan at 10 months postinjury, when edema and hemorrhage had receded, replicated the fiber loss. Using HDFT, the authors accurately identified the presence and location of damage to the underlying white matter in this patient with TBI. Detailed information of injury provided by this novel technique holds future potential for precise neuroimaging assessment of TBI.