028 Évaluation en IRM en séquence de tenseur de diffusion et IRM fonctionnelle pour l’hémianopsie de l’atteinte de radiation optique

Abstract

We performed functional magnetic resonance (fMRI) and diffusion tensor imaging (DTI) for central visual field disorders caused by Wallerien degeneration of the optic radiation and compared the results with those of static perimetry. Three men with a history of cerebral hemorrhage and conservation of the occipital lobe on conventional MR were examined. Visual field testing was performed, and fMRI and DTI were performed with 1.5-T MR scanner. Cortical retinotopy and activity were evaluated with a wedge-shaped rotating checkerboard visual stimulus (rotating wedge) projected on 15 degrees of the central visual field. Functional data were analyzed with Brain Voyagertm software. The optic radiations were visualized with two free software programs, VOLUME ONE v.1.72 and dTV II, developed by the department of radiology of the University of Tokyo. All patients presented central homonymous hemianopia contralateral to the cerebral hemorrhage, suggesting involvement of the optic radiation. In patient 1 and 2 a visual depression of 10 degrees of the central visual field was observed. In patient 3, although visual depression of 5 degrees of the lower part of the central visual field was present, the 5 degrees of upper part was conserved. fMRI demonstrated conservation of activation of the inferior lip of the calcarine fissure on the affected side in patient 3, whereas activation of affected side was not observed in patient 1and 2. These fMRI results were consistent with the central visual field defects. DTI tractography demonstrated marked damage to the optic radiations in all patients but the results were not consistent with the difference in visual field results between them. These fMRI results were consistent with the central visual field defects. DTI tractography demonstrated marked damage to the optic radiations in all patients but the results were not consistent with the difference in visual field results between them. Our results suggest that the optic radiation visualized with DTI corresponds to the central part of the visual field as previously reported (1). The different dysfunctions of the optic radiation were distinguished with fMRI but not with DTI. Further refinement of DTI is needed.