Diffusion tensor MRI evaluation of the corona radiata, cingulate gyri, and corpus callosum in HIV patients.

PURPOSE: To evaluate the white matter integrity of the corona radiata, cingulate gyri, and corpus callosum in patients with human immunodeficiency virus (HIV) infection through diffusion tensor imaging (DTI). MATERIALS AND METHODS: Thirty-four patients with at least 5 years of HIV infection and 27 healthy controls underwent magnetic resonance imaging (MRI) in a 1.5 T scanner. A voxelwise-based technique was used to analyze the DTI data. RESULTS: We found that in the body of corpus callosum the fractional anisotropy (FA) was significantly reduced, whereas mean diffusivity (MD) and radial diffusivity (RD) were increased in HIV patients. Analyzing the corona radiata, axial diffusivity (AD) and MD were significantly increased in the left superior region, MD and RD were increased in the left posterior area, and, furthermore, MD was also increased in the right posterior region. No significant abnormalities were found on the cingulate gyri. The white matter damage, related to FA reduction, was associated with increased RD, indicating that demyelization might be the pathophysiological result of this damage. CONCLUSION: Since the DTI can detect abnormalities in the normal-appearing white matter, this technique may play a role as an early marker of HIV disease progression, including clinical manifestations such as cognitive impairment.

Evaluation of white matter in patients with multiple sclerosis through diffusion tensor magnetic resonance imaging

OBJECTIVE: To study the white matter of patients with multiple sclerosis (MS) with diffusion tensor magnetic resonance (MR) imaging (DTI). METHOD: Forty patients with clinical-laboratorial diagnosis of relapsing-remitting MS and 40 age- and sex-matched controls, who underwent conventional and functional (DTI) MR imaging, were included in the study. The DTI sequences resulted in maps of fractional anisotropy (FA) and regions of interest were placed on the plaques, peri-plaque regions, normal-appearing white matter (NAWM) around the plaques, contralateral normal white matter (CNWM) and normal white matter of the controls (WMC). The FA values were compared and the statistical treatment was performed with the Mann-Whitney U test. RESULTS: The mean FA in plaques was 0.268, in peri-plaque regions 0.365, in NAWM 0.509, in CNWM 0.552 and in WMC 0.573. Statistical significant differences in FA values were observed in plaques, peri-plaque regions and in NAWM around the plaques when compared to the white matter in the control group. There was no significant difference between the FA values of the CNWM of patients with MS and normal white matter of controls. CONCLUSION: Patients with MS show difference in the FA values of the plaques, peri-plaques and NAWM around the plaques when compared to the normal white matter of controls. As a result, DTI may be considered more efficient than conventional MR imaging for the study of patients with MS.

OBJETIVO: Estudar a substância branca de pacientes com esclerose múltipla (EM) através de imagens de ressonância magnética (RM) por tensor de difusão (DTI). MÉTODO: Foram avaliados 40 pacientes com diagnóstico clínico-laboratorial de EM remitente-recorrente e quarenta controles pareados por idade e sexo, os quais foram submetidos à RM convencional e funcional (DTI). As seqüências de DTI resultaram em mapas de anisotropia fracionada (FA) e as regiões de interesse foram posicionadas nas placas, regiões peri-placas, substância branca aparentemente normal (SBAN) ao redor das placas, substância branca normal contra-lateral (SBNC) e substância branca normal do grupo controle (SBC). Os valores de FA foram comparados e a análise estatística foi realizada utilizando o teste Mann-Whitney U. RESULTADOS: A média de FA nas placas foi 0,268, nas regiões peri-placas 0,365, na SBAN 0,509, na SBNC 0,552 e na SBC 0,573. Foram observadas diferenças estatisticamente significativas nos valores de FA nas placas, regiões peri-placas e na SBAN ao redor das placas quando comparados com a SBC. Não houve diferença entre os valores de FA na SBNC dos pacientes com EM e na SBC. CONCLUSÃO: Pacientes com EM demonstram diferença nos valores de FA nas placas, peri-placas e SBAN ao redor das placas quando comparados com a SBC. Assim, o DTI pode ser considerado mais eficiente do que as seqüências de ressonância magnética convencional no estudo dos pacientes com EM.