HIV-associated alterations in normal-appearing white matter
HIV-associated alterations in normal-appearing white matter
复制标题
DOI：
10.1097/qai.0b013e318159d807
复制
发表时间：
2007-12-15
影响因子：
3.6
通讯作者：
Moseley, Michael E.
中科院分区：
文献类型：
--
作者：
Stebbins, Glenn T.;Smith, Clifford A.;Moseley, Michael E.
目的：通过扩散张量成像（DTI）测量白质完整性的不良hiv相关改变有相互矛盾的报道。为了解决这些相互冲突的报告，我们使用高分辨率dtl方法，在逐体素的基础上，评估与hiv相关的放射学定义的正常白质（NAWM）完整性的区域变化。30名hiv阳性（SP）和30名hiv血清阴性（SN）非痴呆的社区居住参与者接受了DTI，以获得全脑白质完整性的测量（分数各向异性[FA]和平均扩散率[MD]）。对于每个参与者，对白质T2体积进行阈值处理以去除异常信号区域，从而产生NAWM掩膜，然后将其应用于FA和MD体积，以提取白质完整性的体素方向的NAWM测量。在控制年龄和药物滥用史的情况下，对FA和MD进行体素组比较（P < 0.005，范围阈值为5体素）。结果：两组在人口统计学和认知表现变量上无显著差异。总的来说，SP组和SN组的全脑FA和MD测量值相等。在SP样本中，药物滥用史与全脑NAWM MD显著增加相关，而丙型肝炎病毒（HCV）合并感染与MD增加的趋势相关。全脑NAWM FA和MD与认知表现测量之间的相关性不显著。DTI测量的区域分析揭示了SP样本中NAWM FA的可变差异，发现FA既减少又增加。NAWM MD的差异更为一致，与SN样本相比，SP样本中普遍增加。与SN样品相比，SP样品中FA显著增加的10个区域中有8个区域的MD也显著增加。结论：即使在非痴呆的社区HIV患者中，放射学定义的NAWM中也存在白质完整性下降。NAWM完整性下降最明显的表现是MD的增加，MD是一种全面性组织破坏的衡量标准。NAWM轴突完整性（FA）的适应症呈现出更复杂的画面，SP样品中FA减少和FA增加。我们在NAWM中可变hiv相关FA变化的发现可能解释了之前关于该人群中DTI参数变化的相互矛盾的报道。我们的研究结果表明，HIV感染导致DTI值的可变变化，反映了轴突完整性的直接丧失和潜在轴突基质复杂性的丧失。
Objective: There are conflicting reports of adverse HIV-associated alterations in white matter integrity as measured by diffusion tensor imaging (DTI). We sought to address these conflicting reports by assessing, on a voxel-by-voxel basis, HIV-associated regional changes in radiologically defined normal-appearing white matter (NAWM) integrity using high-resolution DTLMethods: 30 HIV-scropositive (SP) and 30 HIV-seronegative (SN) nondemented, community-dwelling participants underwent DTI to derive whole-brain measures of white matter integrity (fractional anisotropy [FA] and mean diffusivity [MD]). For each participant, the white matter T2 volume was thresholded to remove regions of abnormal signal, resulting in a NAWM mask, which was then applied to the FA and MD, volumes to extract voxel-wise NAWM measures of white matter integrity. Voxel-wise group comparisons of FA and MD were conducted (P < 0.005, extent threshold 5 voxels) while controlling for age and substance-abuse history.Results: There were no significant differences between the groups for demographic or cognitive performance variables. Summary whole-brain measures of FA and MD were equivalent between the SP and SN samples. Among the SP sample, history of substance abuse was associated with significantly increased whole-brain NAWM MD, and coinfection with hepatitis C virus (HCV) was associated with a trend for increased MD. Correlations between whole-brain NAWM FA and MD with cognitive performance measures were not significant. Regional analyses of DTI measures revealed variable differences in NAWM FA in the SP sample, with findings of both decreased and increased FA. Differences in NAWM MD were more consistent, with widespread increases noted in the SP sample compared to the SN sample. Eight of the 10 regions displaying significantly increased FA in the SP sample were also found to have significantly increased MD compared to the SN sample.Conclusions: Decreased white matter integrity is present even in radiologically defined NAWM in nondemented, community-dwelling patients with HIV The decrease in NAWM integrity is best seen in increases in MD, a measure of generalized tissue breakdown. Indications of NAWM axonal integrity (FA) present a more complicated picture, with both decreased FA and increased FA in the SP sample. Our findings of variable HIV-associated FA changes in NAWM may account for previous conflicting reports of changes in DTI parameters in this population. The results of our study suggest that HIV infection contributes to variable changes in DTI values, reflecting both direct loss of axonal integrity and a loss of complexity to the underlying axonal matrix.