Visual pathway lesion and its development during hyperbaric oxygen treatment: a bold- fMRI and DTI study

To characterize and evaluate functional and anatomic changes of visual pathway lesions during hyperbaric oxygen (HBO) treatment with blood-oxygenation-level-dependent functional MRI (BOLD-fMRI) and diffusion tensor imaging (DTI).

Sixteen patients with visual pathway lesions received HBO treatment. Both BOLD-fMRI and DTI were performed before and after the treatment, while 12 healthy subjects were also studied with 2 examinations as control. The t-tests were used for the comparison of number of activated voxels (AVs) and fractional anisotropy (FA) between the two groups, and within the patient group before and after HBO treatment. Visual acuity of the patient group before and after the treatment was compared using Wilcoxon signed-rank test.

Before the treatment, both AVs (P < 0.01) and FA (P < 0.05) in the bilateral cortexes of occipital lobes were significantly less in the patient group than in the control group. After the treatment, both AVs (P < 0.05) and FA (P < 0.05) were significantly increased. Moreover, The FA of 6 patients with lesions in the optical nerve was greater than the FA of the other 10 patients with lesions in the optic radiation (P < 0.05).

BOLD-fMRI combined with DTI was useful for the characterization and evaluation of anatomic and functional changes of visual pathway lesions and their development during HBO treatment.