Alcaide-Leon P, Pareto D, Martinez-Saez E, Auger C, Bharatha A, Rovira A
From the Department of Radiology, MR Unit (P.A.-L., D.P., C.A., A.R.)
From the Department of Radiology, MR Unit (P.A.-L., D.P., C.A., A.R.).
AJNR Am J Neuroradiol. 2015 May;36(5):871-6. doi: 10.3174/ajnr.A4231. Epub 2015 Jan 29.
Estimates of blood volume and volume transfer constant are parameters commonly used to characterize hemodynamic properties of brain lesions. The purposes of this study were to compare values of volume transfer constant and estimates of blood volume in high-grade gliomas on a pixel-by-pixel basis to comprehend whether they provide different information and to compare estimates of blood volume obtained by dynamic contrast-enhanced MR imaging and dynamic susceptibility contrast-enhanced MR imaging.
Thirty-two patients with biopsy-proved grade IV gliomas underwent dynamic contrast-enhanced MR imaging and dynamic susceptibility contrast-enhanced MR imaging, and parametric maps of volume transfer constant, plasma volume, and CBV maps were calculated. The Spearman rank correlation coefficients among matching values of CBV, volume transfer constant, and plasma volume were calculated on a pixel-by-pixel basis. Comparison of median values of normalized CBV and plasma volume was performed.
Weak-but-significant correlation (P < .001) was noted for all comparisons. Spearman rank correlation coefficients were as follows: volume transfer constant versus CBV, ρ = 0.113; volume transfer constant versus plasma volume, ρ = 0.256; CBV versus plasma volume, ρ = 0.382. We found a statistically significant difference (P < .001) for the estimates of blood volume obtained by using dynamic contrast-enhanced MR imaging (mean normalized plasma volume, 13.89 ± 11.25) and dynamic susceptibility contrast-enhanced MR imaging (mean normalized CBV, 4.37 ± 4.04).
The finding of a very weak correlation between estimates of microvascular density and volume transfer constant suggests that they provide different information. Estimates of blood volume obtained by using dynamic contrast-enhanced MR imaging are significantly higher than those obtained by dynamic susceptibility contrast-enhanced MR imaging in human gliomas, most likely due to the effect of contrast leakage.
血容量和容积转移常数的估计值是常用于表征脑病变血流动力学特性的参数。本研究的目的是逐像素比较高级别胶质瘤中容积转移常数的值和血容量的估计值，以了解它们是否提供不同的信息，并比较通过动态对比增强磁共振成像和动态磁敏感对比增强磁共振成像获得的血容量估计值。
32例经活检证实为IV级胶质瘤的患者接受了动态对比增强磁共振成像和动态磁敏感对比增强磁共振成像，并计算了容积转移常数、血浆容积的参数图以及脑血容量图。逐像素计算脑血容量、容积转移常数和血浆容积匹配值之间的Spearman等级相关系数。对标准化脑血容量和血浆容积的中位数进行比较。
所有比较均显示出弱但显著的相关性（P <.001）。Spearman等级相关系数如下：容积转移常数与脑血容量，ρ = 0.113；容积转移常数与血浆容积，ρ = 0.256；脑血容量与血浆容积，ρ = 0.382。我们发现，通过动态对比增强磁共振成像获得的血容量估计值（平均标准化血浆容积，13.89±11.25）与通过动态磁敏感对比增强磁共振成像获得的血容量估计值（平均标准化脑血容量，4.37±4.04）之间存在统计学显著差异（P <.001）。
微血管密度估计值与容积转移常数之间存在非常弱的相关性，这表明它们提供不同的信息。在人类胶质瘤中，通过动态对比增强磁共振成像获得的血容量估计值显著高于通过动态磁敏感对比增强磁共振成像获得的估计值，这很可能是由于对比剂渗漏的影响。
