Precision of Cerebrovascular Reactivity Assessment with Use of Different Quantification Methods for Hypercapnia Functional MR Imaging
Precision of Cerebrovascular Reactivity Assessment with Use of Different Quantification Methods for Hypercapnia Functional MR Imaging
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DOI：
10.3174/ajnr.a1496
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发表时间：
2009-05-01
影响因子：
3.5
通讯作者：
Auer, D. P.
中科院分区：
文献类型：
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作者：
Goode, S. D.;Krishan, S.;Auer, D. P.
背景和目的：包括脑血管反应性在内的血流动力学功能的非侵入性标测工具正在出现，并可能在临床上用于预测组织的血流动力学风险。一种这样的技术评估响应于高碳酸血症的血氧水平依赖性（BOLD）MR成像对比度，但是其量化的可靠性是不确定的。本研究的目的是前瞻性地调查高碳酸血症功能磁共振成像（fMRI）在健康志愿者的受试者和半球间的变异性和短期）再现性，并评估不同的量化和归一化方法的效果材料和方法：16名健康志愿者，（7名女性和9名男性）进行高碳酸血症fMRI与临床1.5T扫描仪; 8进行了两次扫描。我们使用视觉定义的区组设计或自动回归潮气末（ET）二氧化碳（CO2）来确定BOLD振幅变化。提取全脑、灰质和大脑中动脉区域的绝对信号强度变化百分比（PSC），并将其标准化为ETCO 2变化。受试者间和受试者内（半球和会话之间）的变异系数（COV）的推导。我们使用t检验和U检验评估了不同定量方法对再现性指数的影响。结果：ETCO 2的平均变化为7.8 +/- 3.3 mm Hg。平均BOLD增加从2.54%到2.92%不等。绝对PSC的短期重现性良好（4.8%至10%），但标准化PSC的短期重现性较差（范围，24%至27%COV）。绝对PSC的受试者间重现性在11%至23%之间变化，标准化数据的重现性也较差（32%至39%）。绝对PSC的半球间重现性极好，范围在1.24和2.16%COV之间。结论：总之，使用高碳酸血症fMRI定量脑血管反应性被发现具有良好的会话间和非常好的半球间重现性。该技术有望成为一种诊断工具，特别是对于单侧疾病的敏感检测。
BACKGROUND AND PURPOSE: Tools for noninvasive mapping of hemodynamic function including cerebrovascular reactivity are emerging and may become clinically useful to predict tissue at hemodynamic risk. One such technique assesses blood oxygen level-dependent (BOLD) MR imaging contrast in response to hypercapnia, but the reliability of its quantification is uncertain. The aim of this study was to prospectively investigate the intersubject and interhemispheric variability and short-tern) reproducibility of hypercapnia functional MR imaging (fMRI) in healthy volunteers and to assess the effects of different methods of quantification and normalization.MATERIALS AND METHODS: Sixteen healthy volunteers, (7 women and 9 men) underwent hypercapnia fMRI with a clinical 1.5T scanner; 8 underwent scanning twice. We determined BOLD amplitude changes using a visually defined block design or automated regression to end-tidal ((ET)) carbon dioxide (CO2). Absolute percent signal intensity changes (PSC) were extracted for whole-brain, gray matter, and middle cerebral artery territory, and also normalized to ETCO2 change. Intersubject and intrasubject (between hemispheres and sessions) coefficients of variation (COV) were derived. We assessed the effects of different quantification methods on reproducibility indices using the t test and U tests.RESULTS: The mean change in ETCO2 was 7.8 +/- 3.3 mm Hg. Averaged BOLD increases varied from 2.54% to 2.92%. Short-term reproducibility was good for absolute PSC (4.8% to 10%) but poor for normalized PSC (range, 24% to 27% COV). Intersubject reproducibility varied between 11% and 23% for absolute PSC and, again, was poorer for normalized data (32% to 39%). Interhemispheric reproducibility of absolute PSC was excellent ranging between 1.24 and 2.16% COV.CONCLUSIONS: In conclusion, quantification of cerebrovascular reactivity with use of hypercapnia fMRI was found to have good between-session and very good interhemispheric reproducibility. The technique holds promise as a diagnostic tool, especially for sensitive detection of unilateral disease.