The effect of brain tumor angiogenesis on the in vivo relationship between the gradient-echo relaxation rate change (ΔR2*) and contrast agent (MION) dose
The effect of brain tumor angiogenesis on the in vivo relationship between the gradient-echo relaxation rate change (ΔR2*) and contrast agent (MION) dose
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DOI：
10.1002/jmri.10371
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发表时间：
2003-10-01
影响因子：
4.4
通讯作者：
Schmainda, KM
中科院分区：
文献类型：
--
作者：
Pathak, AP;Rand, SD;Schmainda, KM
目的：为了在体内确定梯度回波成像的敏感性校准因子（k（G）），其表征组织T2* 弛豫速率变化之间的关系，（Δ R2 *）和组织造影剂浓度，与组织类型和条件无关;此外，本发明还涉及一种用于该方法，评估这种假设对使用相对脑血容量（rCBV）的后果测量作为肿瘤血管生成的直接指标。材料和方法：在大鼠脑肿瘤中测量作为单晶氧化铁纳米颗粒（MION）造影剂剂量的函数的DeltaR 2 *（9 L胶质肉瘤）模型，独立测量血液体积分数，计算并比较正常灰质、正常白色物质、肿瘤和对侧脑的k（G）。发现灰色和白色物质的KG相同（P = 0.53），但肿瘤与对侧脑相比存在统计学差异（P = 0.005），其中k（G肿瘤）< k（G脑）。梯度回波校准因子k（G）对于脑灰质和白色物质是相同的，但对于脑和肿瘤组织是不同的。这种差异可能归因于与正常脑相比，肿瘤血管生成和/或可能不同的血液流变学因素（如血细胞比容）导致肿瘤血管形态学的显著不同。因此，当使用梯度回波敏感性造影剂方法时，肿瘤和正常脑组织之间的血容量差异的敏感性可能会降低。
Purpose: To determine in vivo if the susceptibility calibration factor for gradient-echo imaging (k(G)), which characterizes the relationship between the tissue T2* relaxation rate change (DeltaR2*) and tissue contrast agent concentration, is independent of tissue type and condition; in addition, to assess the consequences of such an assumption on the use of relative cerebral blood volume (rCBV) measurements as a direct index of tumor angiogenesis.Materials and Methods: The DeltaR2* was measured as a function of monocrystalline iron oxide nanoparticles (MION) contrast agent dose in a rat brain tumor (9L gliosarcoma) model, the blood volume fraction independently measured, and k(G) calculated and compared for the normal gray matter, normal white matter, tumor, and contralateral brain.Results: The kG was found to be the same for gray and white matter (P = 0.53), but statistically different for tumor compared to contralateral brain (P = 0.005) with k(GTumor) < k(GBrain).Conclusion: The gradient-echo calibration factor, k(G), is the same for brain gray and white matter, but not the same for brain and tumor tissue. This difference may be attributed to the grossly different vascular morphology of tumors, dueto tumor angiogenesis, compared to normal brain and/or possibly differing blood rheological factors such as hematocrit. Consequently, the sensitivity to blood volume differences between tumor and normal brain tissue may be lessened when using gradient-echo susceptibility contrast agent methods.