Department of Medical Biophysics, The University of Western Ontario, London, ON, N6A 3K7, Canada.
Department of Molecular Imaging Program, The University of Western Ontario, London, ON, N6A 3K7, Canada.
Mol Imaging Biol. 2021 Aug;23(4):516-526. doi: 10.1007/s11307-021-01585-1. Epub 2021 Feb 3.
Chemical exchange saturation transfer MRI using an infusion of glucose (glucoCEST) is sensitive to the distribution of glucose in vivo; however, whether glucoCEST is more related to perfusion or glycolysis is still debatable. We compared glucoCEST to computed tomography perfusion (CTP), [F] fluorodeoxyglucose positron emission tomography (FDG-PET), and hyperpolarized [1-C] pyruvate magnetic resonance spectroscopy imaging (MRSI) in a C6 rat model of glioma to determine if glucoCEST is more strongly correlated with measurements of perfusion or glycolysis.
10 C6 glioma cells were implanted in Wistar rat brains (n = 11). CTP (including blood volume, BV; blood flow, BF; and permeability surface area product, PS) and FDG-PET standardized uptake value (SUV) were acquired at 11 to 13 days post-surgery. GlucoCEST measurements (∆CEST) were acquired the following day on a 9.4 T MRI before and after an infusion of glucose solution. This was followed by MRSI on a 3.0 T MRI after the injection of hyperpolarized [1-C] pyruvate to generate regional maps of the lactate:pyruvate ratio (Lac:Pyr). Pearson's correlations between glucoCEST, CTP, FDG-PET, and Lac:Pyr ratio were evaluated.
Tumors had significantly higher SUV, BV, and PS than the contralateral brain. Tumor ∆CEST was most strongly correlated with CTP measurements of BV (ρ = 0.74, P = 0.01) and PS (ρ = 0.55, P = 0.04). No significant correlation was found between glycolysis measurements of SUV or Lac:Pyr with tumor ∆CEST. PS significantly correlated with SUV (ρ = 0.58, P = 0.005) and Lac:Pyr (ρ = 0.75, P = 0.005). BV significantly correlated with Lac:Pyr (ρ = 0.57, P = 0.02), and BF significantly correlated with SUV (ρ = 0.49, P = 0.02).
This study determined that glucoCEST is more strongly correlated to measurements of perfusion than glycolysis. GlucoCEST measurements have additional confounds, such as sensitivity to changing pH, that merit additional investigation.
利用葡萄糖输注的化学交换饱和传递 MRI（glucoCEST）对体内葡萄糖分布敏感；然而，glucoCEST 与灌注或糖酵解的关系仍存在争议。我们比较了 glucoCEST 与计算机断层灌注（CTP）、[F]氟脱氧葡萄糖正电子发射断层扫描（FDG-PET）和极化 [1-C]丙酮酸磁共振波谱成像（MRSI）在 C6 大鼠脑胶质瘤模型中的应用，以确定 glucoCEST 是否与灌注或糖酵解的测量结果相关性更强。
将 10 个 C6 胶质瘤细胞植入 Wistar 大鼠脑内（n = 11）。术后 11 至 13 天采集 CTP（包括血容量，BV；血流，BF；和通透性表面积乘积，PS）和 FDG-PET 标准化摄取值（SUV）。在输注葡萄糖溶液之前和之后的第二天，在 9.4 T MRI 上进行 glucoCEST 测量（∆CEST）。之后，在注射极化 [1-C]丙酮酸后，在 3.0 T MRI 上进行 MRSI，生成乳酸：丙酮酸比（Lac：Pyr）的区域图。评估 glucoCEST、CTP、FDG-PET 和 Lac：Pyr 比值之间的 Pearson 相关性。
肿瘤的 SUV、BV 和 PS 明显高于对侧大脑。肿瘤 ∆CEST 与 CTP 测量的 BV（ρ=0.74，P=0.01）和 PS（ρ=0.55，P=0.04）相关性最强。肿瘤 SUV 或 Lac：Pyr 与肿瘤 ∆CEST 之间未见明显相关性。PS 与 SUV（ρ=0.58，P=0.005）和 Lac：Pyr（ρ=0.75，P=0.005）显著相关。BV 与 Lac：Pyr（ρ=0.57，P=0.02）显著相关，BF 与 SUV（ρ=0.49，P=0.02）显著相关。
本研究确定 glucoCEST 与灌注测量的相关性强于糖酵解。GlucoCEST 测量有额外的混杂因素，如对 pH 变化的敏感性，这值得进一步研究。
