From the Centre for Medical Image Science and Visualization (M.W., I.B.., A.T.)
Division of Cardiovascular Medicine (M.W.).
AJNR Am J Neuroradiol. 2018 Dec;39(12):2194-2199. doi: 10.3174/ajnr.A5870. Epub 2018 Nov 8.
Administration of a gadolinium-based contrast agent is an important diagnostic biomarker for blood-brain barrier damage. In clinical use, detection is based on subjective comparison of native and postgadolinium-based contrast agent T1-weighted images. Quantitative MR imaging studies have suggested a relation between the longitudinal relaxation rate and proton-density in the brain parenchyma, which is disturbed by gadolinium-based contrast agents. This discrepancy can be used to synthesize a contrast-enhancement map based solely on the postgadolinium-based contrast agent acquisition. The aim of this study was to compare synthetic enhancement maps with subtraction maps of native and postgadolinium-based contrast agent images.
For 14 patients with high-grade gliomas, quantitative MR imaging was performed before and after gadolinium-based contrast agent administration. The quantification sequence was multidynamic and multiecho, with a scan time of 6 minutes. The 2 image stacks were coregistered using in-plane transformation. The longitudinal relaxation maps were subtracted and correlated with the synthetic longitudinal relaxation enhancement maps on the basis of the postgadolinium-based contrast agent images only. ROIs were drawn for tumor delineation.
Linear regression of the subtraction and synthetic longitudinal relaxation enhancement maps showed a slope of 1.02 ± 0.19 and an intercept of 0.05 ± 0.12. The Pearson correlation coefficient was 0.861 ± 0.059, and the coefficient of variation was 0.18 ± 0.04. On average, a volume of 1.71 ± 1.28 mL of low-intensity enhancement was detected in the synthetic enhancement maps outside the borders of the drawn ROI.
The study shows that there was a good correlation between subtraction longitudinal relaxation enhancement maps and synthetic longitudinal relaxation enhancement maps in patients with high-grade gliomas. The method may improve the sensitivity and objectivity for the detection of gadolinium-based contrast agent enhancement.
钆基造影剂的给药是血脑屏障损伤的重要诊断生物标志物。在临床应用中，检测基于对原始和基于钆造影剂 T1 加权图像的主观比较。定量磁共振成像研究表明，脑实质中的纵向弛豫率与质子密度之间存在关系，而这种关系会受到基于钆造影剂的干扰。这种差异可用于仅基于基于钆造影剂的采集来合成对比增强图。本研究旨在比较合成增强图与原始和基于钆造影剂图像的减影图。
对 14 例高级别胶质瘤患者进行了钆基造影剂给药前后的定量磁共振成像。定量序列是多动态和多回波的，扫描时间为 6 分钟。使用平面内变换对两个图像堆栈进行配准。在仅基于基于钆造影剂的图像的基础上，对纵向弛豫图进行减影并与合成纵向弛豫增强图相关联。绘制 ROI 以描绘肿瘤。
减影和合成纵向弛豫增强图的线性回归显示斜率为 1.02±0.19，截距为 0.05±0.12。Pearson 相关系数为 0.861±0.059，变异系数为 0.18±0.04。平均而言，在合成增强图的 ROI 边界之外检测到 1.71±1.28 毫升的低强度增强。
研究表明，高级别胶质瘤患者的减影纵向弛豫增强图与合成纵向弛豫增强图之间存在良好的相关性。该方法可能会提高检测基于钆造影剂增强的敏感性和客观性。
