Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, 924 Westwood Blvd, Suite 615, Los Angeles, CA, USA.
J Neurooncol. 2014 Feb;116(3):551-8. doi: 10.1007/s11060-013-1320-2. Epub 2013 Dec 7.
The purpose of this study was to use a retrospective nonlinear distortion correction technique and evaluate the changes in DTI metrics in areas of interest in and around GBM tumors. A total of 24 histologically confirmed GBM patients with pre-operative 20-direction DTI scans were examined. Variability in apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in normal tissue before and after distortion correction were examined. Changes in mean, median and variance of ADC and FA in contrast enhancing and T2/FLAIR ROIs were also examined with and without distortion correction. Results suggest the intra-subject SDs of ADC and FA decreased in normal tissue after the application of distortion correction (P < 0.0001). FA mean and median values decreased after distortion correction in both T1+C and T2 ROIs (P < 0.017), while ADC mean and median values did not significantly change except for the median ADC in T1+C ROIs (P = 0.0054). The intra-subject SD of ADC and FA values in tumor ROIs changed significantly with distortion correction, and Bland-Altman analysis indicated that the bias and the SD of the bias of these intra-subject SDs were larger than those of the mean and median terms. Additionally, the means of the two curves of a double Gaussian fit to the histogram of ADC values from T1+C ROIs, ADCL (mean of lower Gaussian) as well as ADCH (mean of the higher Gaussian) were found to change significantly with distortion correction (P = 0.0045 for ADCL and P = 0.0370 for ADCH). Nonlinear distortion correction better aligns neuro-anatomical structures between DTI and anatomical scans, and significantly alters the measurement of values within tumor ROIs for GBM patients.
本研究旨在使用回顾性非线性失真校正技术，评估脑胶质瘤（GBM）肿瘤及其周围感兴趣区域的弥散张量成像（DTI）指标的变化。共对 24 例经组织学证实的脑胶质瘤患者进行了术前 20 个方向的 DTI 扫描。检查了正常组织在失真校正前后表观扩散系数（ADC）和各向异性分数（FA）的变异性。还检查了在存在和不存在失真校正的情况下，对比增强和 T2/FLAIR 区域的 ADC 和 FA 的均值、中位数和方差的变化。结果表明，在应用失真校正后，正常组织的 ADC 和 FA 的个体内标准差（SD）降低（P<0.0001）。在 T1+C 和 T2 区域，校正后 FA 的均值和中位数降低（P<0.017），而 ADC 的均值和中位数除了 T1+C 区域的中位数 ADC（P=0.0054）外，没有显著变化。肿瘤区域的 ADC 和 FA 值的个体内 SD 在失真校正后变化显著，Bland-Altman 分析表明，这些个体内 SD 的偏倚和偏倚 SD 的偏差大于均值和中位数的偏差。此外，从 T1+C 区域的 ADC 值直方图拟合双高斯曲线的两个曲线的均值 ADCL（较低高斯的均值）和 ADCH（较高高斯的均值），发现与失真校正显著相关（P=0.0045 用于 ADCL 和 P=0.0370 用于 ADCH）。非线性失真校正可以更好地对齐 DTI 和解剖扫描之间的神经解剖结构，并显著改变脑胶质瘤患者肿瘤区域内的数值测量。
