Combination study of functional magnetic resonance imaging and diffusion tensor imaging on post visual pathways in patients with pituitary macroadenoma

Abstract

Objective To evaluate the anatomy and function of post visual pathways in patients with pituitary macroadenoma by functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) and analyze the effect of pituitary macroadenoma on optic radiation and visual cortex. Methods Twenty-three patients with pituitary macroadenoma(patients group) and eighteen matched healthy volunteers (control group) were recmited in this study. Block-designed fMRI and DTI were performed with 1.5 T magnetic resonance scanner. During fMRI examination, black and white check board and white + in black screen center were used as stimulus and control respectively. Bilateral eyes in two groups received stimulus individually. The fMRI data were processed with SPM2. Different mappings between two groups during bilateral eyes examination were obtained respectively with inter-group analysis. Thirteen diffusion sensitive directions were used during DTI examination with b value 1000 s/mm2. Volume-one software was used to process the DTI data, and FA value of bilateral optic radiation was measured. The difference of the FA value of optic radiation between two groups was compared. Results The numbers of patients selected for group analysis in left and right eye examination were both twelve after head motion and mechanical noise effects were ruled out. Compared to control group, activated extent and intensity of primary visual cortex decreased in patients group, especially in contralateral visual cortex (P<0.05). The FA value of bilateral optic radiation in patients group decreased obviously compared with control group(left: 0.52±0.06 vs 0.58±0.04, t=3.45, P<0.01; fight: 0.50 ± 0.05 vs 0.60 ± 0.04, t=5.77, P<0.01). Conclusions The patients with pituitary macroadenoma may present changed microstructure and decreased function of post visual pathways. Combinated application of fMRI and DTI is an effective method for early detecting the changes of cerebral structures and function. Key words: Pituitary macroadenoma; Magnetic resonance imaging, functional; Diffusion tensorimaging; Visual cortex ; Optic radiation