基于体素的形态学测量结合ASL在脊髓小脑共济失调3型诊断中的应用价值

Value of voxel-based morphometry combined with pulsed arterial spin marker perfusion imaging in the diagnosis of spinocerebellar ataxia type 3

目的 探讨基于体素的形态学测量方法 (VBM)结合3D脉冲式动脉自旋标记灌注成像(3D-PASL)对脊髓小脑共济失调3型(SCA3)的诊断价值。方法 前瞻性收集2018年5月~2019年5月经基因检测证实为SCA3的患者,并募集与其性别、年龄、身体质量指数(BMI)匹配的健康志愿者。对所有入组者行基于全脑的T1WI磁化强度预备快速梯度回波(T1MPRAGE)和3D-PASL扫描,获得被试者经Dartel配准后的全脑标准化灰质概率图以及全脑脑血流量(CBF)图。进一步通过组间VBM比较确定灰质体积显著差异的脑区及其特利尔神经研究所(MNI)标准空间坐标作为兴趣区,提取相应脑区的CBF值,并通过非参数检验和受试者工作特性曲线(ROC)分析评价其对SCA3的诊断价值。结果 相比健康对照[n=12,平均(36.92±14.26)岁],VBM示SCA3患者[n=19,平均(40.89±13.72)岁]的右侧小脑半球存在灰质体积显著减低区域,主要位于右侧小脑前叶(MNI坐标x:18,y:-54,z:-19.5)(P<0.05,FWE校正)。进一步对比分析相应区域的CBF值,结果表明SCA3患者右侧小脑前叶的CBF值(56.0±30.9) ml/100 g/min明显高于对照组(29.6±21.0)ml/100 g/min(P<0.05)。ROC分析显示,基于右侧小脑前叶的CBF对SCA3具有中等程度的诊断效能,曲线下面积(AUC)为0.75,特异度、敏感度和界值分别为75.0%、84.2%和29.8 ml/100 g/min。结论 相比健康对照,SCA3患者的右侧小脑前叶灰质体积显著减低,相应区域CBF增高。基于右侧小脑前叶的CBF值可用于诊断SCA3。

Objective To explore the value of voxel-based morphometry(VBM) combined with 3-dimensional pulsed arterial spin labeling(3D-PASL) perfusion imaging for diagnosing spinocerebellar ataxia type 3(SCA3). Methods Nineteen genetically identified SCA3 patients [mean age:(40.89±13.72) years] as well as 12 age, sex, and body mass index-matched healthy volunteers [mean age:(36.92 ±14.26) years] were recruited into the study from May 2018 to May 2019. The whole-brain T1-weighted magnetization-prepared rapid acquisition of gradient echo(T1-MPRAGE) and 3D-PASL imaging was performed on all subjects. The Dartel normalized whole brain gray matter VBM and cerebral blood flow(CBF) map were obtained through post-processing. The brain regions with significant alterations in gray matter volume were determined by a comparative analysis between the two groups. The CBF values of the corresponding brain regions were then extracted. The diagnostic value of CBF for SCA3 was analyzed by non-parametric tests and receiver operating characteristic(ROC) curve. Results VBM of SCA3 patients showed significantly( P<0.05, FWE corrected) reduced gray matter volume than the healthy control mainly in the right anterior cerebellar hemisphere with Montreal Neurological Institute coordinates of x: 18, y:-54, z:-19.5.The CBF of the right anterior cerebellar hemisphere in SCA3 patients [(56.0 ±30.9) ml/100 g/min] was significantly higher( P<0.05)than that of the control group [(29.6±21.0) ml/100 g/min]. ROC analysis showed that CBF cut-off value of 29.8 ml/100 g/min in the right anterior cerebellar hemisphere had medium diagnostic efficacy for SCA3 with 0.75 area under the ROC curve, 75.0% specificity, and 84.2% sensitivity. Conclusion Patients with SCA3 have reduced volume of gray matter and increased CBF in the right anterior cerebellar hemisphere. The regional CBF can be used to diagnose SCA3 with moderately high sensitivity.