Diffusion tensor imaging study of early white matter integrity in HIV-infected patients: A tract-based spatial statistics analysis

ObjectiveHIV preferentially affects brain, especially white matter (WM). We used diffusion tensor imaging (DTI) and tract-based spatial statistics (TBSS) to analyze early changes of the white matter in HIV-infected patients with normal appearance on conventional MRI.MethodsDiffusion tensor imaging data of 20 HIV-infected (HIV+) subjects not receiving cART (HIV+/cART−), 20 HIV+ subjects receiving stable cART (HIV+/cART+) for at least 12 consecutive weeks prior to study, and 20 HIV negative (HIV−) controls with matched age and sex. Using TBSS analysis method, the voxel-based differences in fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD) of the global white matters were respectively compared between the HIV+/cART− group and the HIV− group, the HIV+/cART+ group and the HIV- group, the HIV+/cART− group and the HIV+/cART+ group. The correlation analysis was performed between diffusion parameters in brain regions with significant difference and CD4+ counts in the HIV+ group.ResultsThere were no statistical significances in white matter values (FA, MD, AD, RD) between HIV+/cART− group and HIV+/cART+ group. Compared with HIV− controls, HIV+/cART− patients showed significant increased MD in genu of corpus callosum (GCC), body of corpus callosum (BCC), splenium of corpus callosum (SCC), fornix (FOR) , bilateral anterior limb of internal capsule (ALIC), anterior corona radiate (ACR), superior corona radiate (SCR), posterior corona radiate (PCR), external capsule (EC), cingulum (cingulate gyrus) (CIN-CG), cingulum (hippocampus) (CIN–H), superior longitudinal fasciculus (SLF), right retrolenticular part of internal capsule (RIC), left posterior thalamic radiation (PTR); significant increased AD in GCC, BCC, SCC, FOR, bilateral ALIC, posterior limb of internal capsule (PLIC), RIC, ACR, SCR, PCR, EC, CIN-CG, CIN–H, SLF; significant increased RD in GCC, BCC, SCC, bilateral ALIC, ACR, SCR, PCR, PTR, EC, SLF, left CIN-CG (all P < 0. 05); No areas with FA changes were found. Compared with HIV- controls, HIV+/cART+ patients showed significant increased MD in GCC, BCC, SCC, FOR, bilateral ALIC, ACR, SCR, PCR, PTR, EC, CIN-CG, SLF, right PLIC, RIC, left CIN-H; significant increased AD in GCC, BCC, SCC, FOR, bilateral ALIC, PLIC, ACR, SCR, PCR, EC, CIN-CG, SLF, left RIC, right PTR; significant increased RD in GCC, BCC, SCC, bilateral ACR, SCR, PCR(all P < 0. 05); the difference of FA in every region was not significant between the two groups. In HIV+/cART− group, significant negative correlations were found between DTI indices (MD, RD values) and CD4+ counts in significant clusters (r = −0. 457, p = 0. 034; r = −0. 494, p = 0. 027).ConclusionMultiple cerebral white matter fiber tracts are damaged in HIV-infected patients without cognitive impairment. Quantitative analysis of DTI using TBSS is valuable in evaluating changes of HIV-associated white matter microstructures.