Shin Ji Hoon, Lee Ho Kyu, Kwun Byung Duk, Kim Jin-Suh, Kang Weechang, Choi Choong Gon, Suh Dae Chul
Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Songpa-gu, Seoul, South Korea.
AJR Am J Roentgenol. 2002 Sep;179(3):783-9. doi: 10.2214/ajr.179.3.1790783.
Relative cerebral blood flow has rarely been studied as part of the preoperative assessment of tumor grade, although relative cerebral blood volume is known to be useful for this assessment. The purpose of our study was to determine the usefulness of relative cerebral blood flow in assessing the histopathologic grade of cerebral gliomas.
MR imaging was performed in 17 patients with proven cerebral gliomas (11 high-grade gliomas and six low-grade gliomas), using a first-pass gadopentetate dimeglumine-enhanced T2-weighted echoplanar perfusion sequence. The perfusion data were deconvoluted with an arterial input function, using singular value decomposition to obtain a color map of relative cerebral blood volume and flow; the relative cerebral blood volume and flow ratios were expressed relative to values measured in the contralateral white matter. The Wilcoxon's rank sum test was performed to test the difference between the mean of the relative cerebral blood volume (or flow) ratio in high-grade gliomas and that in low-grade gliomas. Receiver operating characteristic curve analysis was used to evaluate the association between the relative cerebral blood volume (or flow) ratio and the grade of the glioma, as well as to calculate the relative cerebral blood volume and flow ratio cutoff value permitting discrimination between high- and low-grade gliomas. The correlation between relative cerebral blood volume and flow ratios was evaluated using Spearman's rank correlation analysis. We also made a qualitative assessment regarding the match or mismatch of areas of maximal contrast enhancement with the areas of highest color perfusion maps.
The mean of the relative cerebral blood volume ratio was 4.91 in the high-grade gliomas and 2.00 in the low-grade gliomas. The mean relative cerebral blood flow ratio was 4.82 in the high-grade gliomas and 1.83 in the low-grade gliomas. A significant difference in each relative cerebral blood volume and flow ratio was found between the high- and low-grade gliomas (Wilcoxon's rank sum test, p < 0.05). Both the relative cerebral blood volume and flow ratios strongly matched the grade of the glioma, but the difference between the two areas was not significant (receiver operating characteristic curve analysis, p > 0.05). The desired cutoff value was 2.93 in the relative cerebral blood volume ratio and 3.57 in the relative cerebral blood flow ratio. Additionally, there was a strong correlation between the relative cerebral blood volume and flow ratios (Spearman's rank correlation coefficient = 0.762; p < 0.05). There was frequent mismatch (33%) between the qualitative assessment of the contrast-enhanced T1-weighted MR images and the perfusion maps.
First-pass gadopentetate dimeglumine-enhanced T2-weighted echoplanar perfusion MR imaging is useful for the preoperative assessment of tumor grade. A relative cerebral blood flow ratio, in addition to a relative cerebral blood volume ratio, can be a useful tool in the evaluation of the histopathologic grade of cerebral gliomas.
尽管已知相对脑血容量有助于术前评估肿瘤分级，但相对脑血流量作为肿瘤分级术前评估的一部分却鲜有研究。我们研究的目的是确定相对脑血流量在评估脑胶质瘤组织病理学分级中的作用。
对17例经证实的脑胶质瘤患者（11例高级别胶质瘤和6例低级别胶质瘤）进行磁共振成像检查，采用首过钆喷酸葡胺增强T2加权回波平面灌注序列。使用奇异值分解法对灌注数据与动脉输入函数进行去卷积处理，以获得相对脑血容量和血流的彩色图；相对脑血容量和血流比值相对于对侧白质测量值表示。采用Wilcoxon秩和检验来检验高级别胶质瘤与低级别胶质瘤中相对脑血容量（或血流）比值均值之间的差异。采用受试者工作特征曲线分析来评估相对脑血容量（或血流）比值与胶质瘤分级之间的关联，以及计算可区分高级别和低级别胶质瘤的相对脑血容量和血流比值临界值。使用Spearman秩相关分析评估相对脑血容量与血流比值之间的相关性。我们还对最大对比增强区域与最高彩色灌注图区域的匹配或不匹配情况进行了定性评估。
高级别胶质瘤的相对脑血容量比值均值为4.91，低级别胶质瘤为2.00。高级别胶质瘤的相对脑血流比值均值为4.82，低级别胶质瘤为1.83。高级别和低级别胶质瘤之间在每个相对脑血容量和血流比值上均存在显著差异（Wilcoxon秩和检验，p<0.05）。相对脑血容量和血流比值均与胶质瘤分级密切匹配，但两个区域之间的差异不显著（受试者工作特征曲线分析，p>0.05）。相对脑血容量比值的理想临界值为2.93，相对脑血流比值为3.57。此外，相对脑血容量与血流比值之间存在强相关性（Spearman秩相关系数=0.762；p<0.05）。对比增强T1加权磁共振图像与灌注图的定性评估之间经常存在不匹配（33%）。
首过钆喷酸葡胺增强T2加权回波平面灌注磁共振成像有助于术前评估肿瘤分级。除相对脑血容量比值外，相对脑血流比值也可作为评估脑胶质瘤组织病理学分级的有用工具。
