CORRECTION FOR HEAD SIZE IN BRAIN-IMAGING MEASUREMENTS
CORRECTION FOR HEAD SIZE IN BRAIN-IMAGING MEASUREMENTS
复制标题
DOI：
10.1016/s0165-1781(05)80006-x
复制
发表时间：
1993-06-01
影响因子：
2.3
通讯作者：
PFEFFERBAUM, A
中科院分区：
文献类型：
--
作者：
MATHALON, DH;SULLIVAN, EV;PFEFFERBAUM, A
基于计算机断层扫描（CT）或磁共振成像（MRI）的结构性脑成像测量通常会根据头部大小的正常变化进行校正或调整。一些头部尺寸校正方法，如脑室-脑比率（VBR），是基于将大脑结构尺寸作为估计头部尺寸的比例，而其他方法则使用回归模型来获得头部尺寸残差结构测量。最近，头部尺寸校正被证明会导致大脑结构的体积测量不太可靠（Arndt等人，1991年）。在本研究中，MRI被用来检查头部大小校正对灰质、白色物质和脑脊液体积测量的评价者间可靠性的影响。四名评分员独立地对来自26名受试者的MRI脑图像进行评分，分别估计头部大小和感兴趣区域（ROI）大小。使用两种方法来校正头部大小差异的MRI值，一种基于比例，另一种基于线性回归。结果证实，头部尺寸校正确实产生了较低的信度的措施，然而，基于经典测量理论的进一步分析表明，较低的信度不仅是由于测量误差方差增加，但也减少了真实得分方差。随后的标准有效性分析比较了原始（未校正）和头部大小校正的ROI措施，在他们的相关性与年龄的样本中的43个正常对照组，并在他们的能力，以区分精神分裂症患者（n = 22）从正常对照组（n = 20）。结果表明，头部大小校正往往提高标准的有效性，产生更高的相关性与年龄和诊断状态比原始措施。这些研究结果表明，头部大小校正删除不相关的真实分数的变化，降低了可靠性，但提高了与有效性标准，如年龄和诊断状态的相关性。
Structural brain-imaging measurements based on computed tomography (CT) or magnetic resonance imaging (MRI) are often corrected or adjusted for normal variation in head size. Some methods of head-size correction, such as the ventricle-brain ratio (VBR), are based on taking the brain structure size as a proportion of the estimated head size, while other methods have used a regression model to obtain head-size residualized structure measures. Recently, head-size correction was shown to result in less reliable volumetric measures of brain structures (Arndt et al., 1991). In the present study, MRI was used to examine the effects of head-size correction on the interrater reliability of volumetric measures of gray matter, white matter, and cerebrospinal fluid. Four raters independently scored MRI brain images from 26 subjects, generating separate estimates of head size and region of interest (ROI) size. Two methods were used to correct MRI values for differences in head size, one based on proportions and the other based on linear regression. Results confirmed that head-size correction did produce measures with lower reliability; however, further analysis based on classical measurement theory showed that the lower reliability was attributable not only to increased measurement error variance, but also to reduced true score variance. Subsequent analyses of criterion validity compared the raw (uncorrected) and head-size-corrected ROI measures in terms of their correlations with age in a sample of 43 normal control subjects, and in terms of their ability to differentiate schizophrenic patients (n = 22) from normal control subjects (n = 20). Results indicated that head-size correction often improved criterion validity, producing higher correlations with age and with diagnostic status than those produced by the raw measures. These findings suggest that head-size correction removes irrelevant true-score variance which reduces reliability yet improves the correlations with validity criteria such as age and diagnostic status.