Diffusion tensor imaging analysis of long association bundles in the presence of an arteriovenous malformation.

Abstract

Conventional imaging demonstrates intertwined fibers of the cerebral white matter as a homogeneous substrate. Recently, diffusion tensor imaging has allowed 3D reconstruction of these fiber bundles. The goal of this study was to analyze the modifications of the association fibers induced by an arteriovenous malformation (AVM) in the parietotemporooccipital (PTO) associative area and their clinical significance. The authors analyzed the long association fibers in seven patients harboring an AVM in or near the PTO region in relation with the fibers' clinical manifestation. The fibers include the arcuate fasciculus (AF), the occipitofrontal fasciculus (OFF), and the inferior longitudinal fasciculus (ILF). These structures were compared with the contralateral bundles. The modification of the tracts could establish a pattern signature depending on the specific location of the vascular malformation. There was a positive correlation between the degree of modifications of OFF and ILF fiber tracts and visual deficits. Alteration of the AF correlated with a speech disorder and the risk of postoperative deficits. Diffusion tensor imaging enables in vivo dissection of fiber tracts coursing through the PTO area. Depending on the location of the AVMs, long association fibers are variously modified. These findings correlate with clinical manifestations and may predict outcome after surgery.