Division of Neuroradiology, Vascular and Interventional Radiology, Department of Radiology, Medical University of Graz, Auenbruggerplatz 9, 8036 Graz, Austria.
Division of General Radiology, Department of Radiology, Medical University of Graz, Auenbruggerplatz 9, 8036 Graz, Austria.
Eur J Radiol. 2024 Sep;178:111659. doi: 10.1016/j.ejrad.2024.111659. Epub 2024 Jul 31.
Calculation of extracellular volume fraction (ECV), a marker of myocardial fibrosis in cardiac magnetic resonance imaging (CMR), requires hematocrit (Hct). We aimed to correlate Hct levels with native blood T1 times, to derive a formula for estimating synthetic Hct (Hct) and synthetic ECV (ECV), to assess accuracy of ECV and to compare our model with published formulas.
In this retrospective study, a cohort of 250 CMR scans with T1 mapping (3T, MOLLI 5(3)3, endsystolic aquisition), was divided into a derivation and validation cohort. Native T1 times of the left ventricular blood pool (T1) were correlated with Hct levels from blood sampling within 24 h (Hct) and a formula for calculation of Hct was derived by linear regression.
In the derivation cohort (n = 167), Hct showed a good association with T1 (r = -0.711, p < 0.001). The resulting regression equation was Hctsyn = 1/T1 * 1355.52-0.310. In the validation cohort (n = 83), Hct and Hct showed good correlation (r = 0.726, p < 0.001), while ECV, and ECV demonstrated excellent correlation (r = 0.940, p < 0.001). ECV had a minimal bias of 0.28 % and the misclassification rate (8.8 %) was comparable to the variability introduced by repeated Hct measurements (misclassification in 7.5 %). Applying published formulas in our cohort resulted in incorrect classification in up to 60 %.
We provide a formula for estimating Hct from native blood T1 on a 3T scanner. The measurement error of ECV is low and comparable to the error due to retest variability of conventional Hct. Scanner- and sequence-specific formulas should be used.
计算细胞外容积分数（ECV），一种心脏磁共振成像（CMR）心肌纤维化的标志物，需要红细胞压积（Hct）。我们旨在将 Hct 水平与原生血 T1 时间相关联，得出一种估计合成 Hct（Hct）和合成 ECV（ECV）的公式，评估 ECV 的准确性，并与已发表的公式进行比较。
在这项回顾性研究中，我们对 250 例接受 T1 映射（3T，MOLLI 5(3)3，收缩末期采集）CMR 扫描的患者进行了研究，将其分为推导队列和验证队列。左心室血池的原生 T1 时间（T1）与 24 小时内采血的 Hct 水平（Hct）相关联，并通过线性回归得出计算 Hct 的公式。
在推导队列（n=167）中，Hct 与 T1 呈良好相关性（r=-0.711，p<0.001）。得出的回归方程为 Hctsyn=1/T1*1355.52-0.310。在验证队列（n=83）中，Hct 和 Hct 之间具有良好的相关性（r=0.726，p<0.001），而 ECV 和 ECV 则具有极好的相关性（r=0.940，p<0.001）。ECV 的偏差最小为 0.28%，错误分类率（8.8%）与常规 Hct 重复测量的变异性（7.5%的错误分类）相当。在我们的队列中应用已发表的公式可能导致高达 60%的错误分类。
我们提供了一种在 3T 扫描仪上从原生血 T1 估计 Hct 的公式。ECV 的测量误差较低，与常规 Hct 重复测量的变异性引起的误差相当。应使用特定于扫描仪和序列的公式。
