[The preliminary study of white matter integrity in patients with olfactory dysfunction]

Objective: To investigate the white matter integrity in patients with olfactory dysfunction using diffusion tensor imaging (DTI). Methods: Twenty-one patients with olfactory dysfunction and sixteen age, sex and level of education matched normal subjects were recruited in this study. Sniffin' Sticks olfactory test was performed to evaluate the olfactory function of all subjects. We acquired diffusion tensor images with a echo planar imaging (EPI) sequence from all subjects on a 3T scanner. The fractional anisotropy (FA) images were performed using DTI-studio, and bilateral piriform cortex, orbitofrontal cortex, hippocampus and insula cortex adjacent white matter as well as capsula interna were delineated from the FA images as the region of interest associated with olfactory (ROI(awo)) manually. Independent sample t test analysis was used to compare the FA value of all ROI(awo) between the controls and patients. Results: In olfactory dysfunction group, the FA value of adjacent white matter of right piriform cortex and orbitofrontal cortex were significantly lower than those of control group (0.42±0.05 (x±s) vs 0.45±0.05, 0.43±0.06 vs 0.49±0.07, t value was 2.32, 2.79, respectively, all P<0.05). The FA value of adjacent white matter of left piriform cortex and orbitofrontal cortex had no significant difference compared with those of control group (0.43±0.05 vs 0.45±0.04, 0.44±0.04 vs 0.47±0.06, t value was 1.65, 1.37, respectively, all P>0.05). The FA value of the adjacent white matter of bilateral hippocampus, insula cortex and capsula interna had no significant difference compared with those of control group, neither (0.45±0.08 vs 0.44±0.08, 0.45±0.09 vs 0.44±0.10, 0.41±0.08 vs 0.39±0.07, 0.41±0.07 vs 0.38±0.05, 0.64±0.08 vs 0.63±0.08, 0.64±0.07 vs 0.63±0.07, t value was 0.30, 0.15, 0.88, 1.34, 0.14, 0.35, respectively, all P>0.05). Conclusions: The patients with olfactory dysfunction showed abnormal white matter connection in the major primary and secondary olfactory cortex. The reduced white matter integrity in ROI(awo) might contribute to the pathogenesis of olfactory dysfunction.