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目的探讨0期无症状HIV相关性痴呆(HAD)常规MRI检查表现正常的脑白质磁共振扩散张量成像(DTI)的改变及其早期诊断价值。方法对32例0期无症状HAD患者和29名与之年龄、性别相匹配的健康志愿者为对照行MRI扫描,获取常规MRI(T1WI、T2WI、T2FLAIR)及DTI图像,测量其额叶、顶叶、颞叶、枕叶、胼胝体膝部、压部、内囊前、后肢白质区部分各向异性分数(FA)和表观扩散系数(ADC)。利用独立样本t检验比较HIV患者与对照组的FA值及ADC值。进一步根据CD4+计数将患者分为两组,即CD4+<200/mm3组、CD4+>200/mm3组,利用单因素方差分析比较CD4+<200/mm3组、CD4+>200/mm3组的HIV患者及对照组的FA值及ADC值。结果与正常对照组比较,0期无症状HAD患者的额叶、顶叶、颞叶、枕叶、胼胝体膝部、压部、内囊前、后肢白质的FA值均有所降低,但差异无统计学意义(P>0.05);对应ADC值呈不同幅度的增加:额叶、枕叶、内囊前肢白质显著增加(P<0.05),而顶叶、颞叶、胼胝体膝部、压部、内囊后肢白质区域的差异均无统计学意义(P>0.05)。另外,CD4+T细胞数<200/mm3的HIV患者额叶、枕叶白质的ADC值显著高于CD4+T细胞数>200/mm3的HIV患者及正常对照组(P<0.05),而对应FA值的差异均无统计学意义(P>0.05)。结论对无症状期HAD患者行定量DTI分析,有助于评价HAD患者在常规MRI检查表现正常的脑区的微结构改变,进而有助于HAD的早期诊治,阻止或逆转认知下降。定量ADC值的变化表明HAD疾病早期损害优先出现在额叶、枕叶,其结构特点(与高级皮层功能相关的脑区)可能是HAD早期易受损害的重要原因。此外,低CD4+T淋巴细胞计数可能是HIV患者进展为HAD的重要危险因素之一。
Objective To investigate the changes and early diagnosis of magnetic resonance diffusion tensor imaging (DTI) with normal MRI findings of asymptomatic HIV-associated dementia (HAD) Methods Thirty-two patients with asymptomatic HAD in stage 0 and 29 healthy volunteers matched with their age and sex were selected as controls and scanned by conventional MRI (T1WI, T2WI, T2FLAIR) and DTI images. The anisotropy fraction (FA) and apparent diffusion coefficient (ADC) of white matter in the leaves, temporal lobe, occipital lobe, corpus callosum knee, the pressure part, the anterior and the hind limbs of the internal capsule were measured. The independent sample t-test was used to compare the FA values and ADC values between HIV patients and controls. The patients were further divided into two groups according to the CD4 + count: CD4 + <200 / mm3 group and CD4 +> 200 / mm3 group. One-way ANOVA was used to compare HIV patients with CD4 + <200 / mm3 group and CD4 +> 200 / Group FA value and ADC value. Results Compared with the normal control group, the FA values of white matter in the frontal lobe, parietal lobe, parietal lobe, temporal lobe, occipital lobe, corpus callosum in the 0 stage asymptomatic HAD patients were decreased, but the differences were not significant (P <0.05). The corresponding ADC values increased in different amplitudes: the frontal lobe, occipital lobe and the white matter of the forelimb were significantly increased (P <0.05), while the parietal lobe, temporal lobe, corpus callosum knee, There was no significant difference in the white matter area of the posterior limb of the internal capsule (P> 0.05). In addition, the ADC values of frontal lobe and occipital lobe white matter in HIV patients with CD4 + T cells <200 / mm3 were significantly higher than those in HIV + CD4 + T cells> 200 / mm3 and normal controls (P <0.05) FA values were no significant difference (P> 0.05). Conclusions Quantitative DTI analysis of asymptomatic patients with HAD can be helpful to evaluate the changes of microstructure in normal brain regions of HAD patients, which will be helpful for the early diagnosis and treatment of HAD and prevent or reverse the cognitive decline. Changes in quantitative ADC values suggest that early lesions in HAD disease preferentially occur in the frontal and occipital lobe and structural features (brain regions associated with higher cortical function) may be an important cause of early vulnerability to HAD. In addition, low CD4 + T lymphocyte counts may be one of the important risk factors for progression to HAD in HIV patients.