Diffusion tensor imaging is alternative for measuring functional brain injury

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Diffusion tensor imaging (DTI) is an effective a surrogate marker of brain tissue integrity, according to a study published in the September issue of Archives of Neurology.

DTI characterizes multiple sclerosis (MS) tissue injury, although it has remained unproven whether DTI changes in disease have functional consequences. The medial longitudinal fasciculus (MLF) is a key brainstem pathway for ocular adduction and is commonly injured in patients with MS, typically resulting in internuclear ophthalmoparesis, according to the study’s background information.

Researchers sought to validate DTI as a physiologically relevant measure of brain tissue integrity in a correlation study of ocular dysmotility and DTI in six patients with chronic, unilateral, or bilateral internuclear ophthalmoparesis and 10 healthy control subjects.

The study as conducted at the Multiple Sclerosis Center, University of Texas Southwestern Medical Center in Dallas between January and September 2004.

Within the pontine MLF, the researchers said that the mean diffusivity was increased compared with healthy controls, whereas the pontine lattice index was decreased. Correlations were observed between the velocity versional dysconjugacy index and the mean diffusivity. Similar correlations were found between the versional dysconjugacy index and the lattice index.

“We identified DTI evidence of pathologic disruption of a small brainstem fiber pathway, which is crucial for accurate horizontal eye movements. In this small study, we observed correlations between the DTI changes and oculomotor dysfunction. Our preliminary observations provide criterion validity of DTI as a surrogate marker of brain tissue integrity,” the authors wrote.