Biomedical NMR Research Center, Department of Radiology, Dartmouth College, Hanover, New Hampshire, USA.
J Magn Reson Imaging. 2014 Jan;39(1):110-9. doi: 10.1002/jmri.24097. Epub 2013 Apr 1.
To study vascular responsiveness to hypoxia and hypercarbia together with vessel size index (VSI) in a 9L rat glioma (n = 11) using multimodal MRI.
VSI was determined using T2 and T2* MRI following AMI-227 contrast agent. Blood oxygenation level dependent (BOLD) signal response was determined using T2 EPI MRI, blood volume changes using AMI-227 and blood flow by means of continuous arterial spin labeling.
VSI in the cortex, tumor rim, and core of 2.2 ± 1.0, 18.2 ± 5.4, and 23.9 ± 14.7 μm, respectively, showing a larger average vessel size in glioma than in the brain parenchyma. BOLD and blood volume signal changes to hypoxia and hypercapnia were much more profound in the tumor rim than the core. Hypoxia led to rim BOLD signal change that was larger in amplitude and it attained the low value much faster than either core or brain cortex. The vasculature in the rim appears more responsive to respiratory challenges in terms of volume adaptation than the core. Blood flow values within the gliomas were much lower than in the contralateral brain. Neither hypercarbia nor hypoxia had an effect on the tumor blood flow.
Vascular responses of 9L gliomas to respiratory challenge, in particular hypoxia, are heterogeneous between the core and rim zones, potentially offering a means to classify and separate intratumor tissues with differing hemodynamic characteristics.
使用多模态 MRI 研究 9L 大鼠神经胶质瘤中的血管对缺氧和高碳酸血症的反应以及血管大小指数（VSI）。
使用 AMI-227 造影剂后的 T2 和 T2* MRI 确定 VSI。使用 T2 EPI MRI 确定血氧水平依赖（BOLD）信号响应，使用 AMI-227 确定血容量变化，通过连续动脉自旋标记确定血流。
皮质、肿瘤边缘和核心的 VSI 分别为 2.2±1.0、18.2±5.4 和 23.9±14.7μm，表明胶质瘤中的平均血管大小大于脑实质。肿瘤边缘的 BOLD 和血容量信号对缺氧和高碳酸血症的变化比核心更为明显。缺氧导致边缘 BOLD 信号变化幅度更大，达到低值的速度比核心或大脑皮层都快。就体积适应而言，边缘的血管系统对呼吸挑战的反应更为敏感。胶质瘤内的血流值远低于对侧大脑。高碳酸血症和缺氧均未对肿瘤血流产生影响。
9L 神经胶质瘤对呼吸挑战的血管反应，特别是缺氧，在核心和边缘区域之间存在异质性，这可能为分类和分离具有不同血流动力学特征的肿瘤内组织提供一种方法。
