METHODS: 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 (T1native,midLV) were correlated with Hct levels from blood sampling within 24 h (Hct24h) and a formula for calculation of Hctsyn was derived by linear regression.
RESULTS: In the derivation cohort (n = 167), Hct24h showed a good association with T1native,midLV (r = -0.711, p < 0.001). The resulting regression equation was Hctsyn = 1/T1native,midLV * 1355.52-0.310. In the validation cohort (n = 83), Hctsyn and Hct24h showed good correlation (r = 0.726, p < 0.001), while ECVsyn, and ECV24h demonstrated excellent correlation (r = 0.940, p < 0.001). ECVsyn 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 %.
CONCLUSIONS: We provide a formula for estimating Hctsyn from native blood T1 on a 3T scanner. The measurement error of ECVsyn is low and comparable to the error due to retest variability of conventional Hct. Scanner- and sequence-specific formulas should be used.
方法:在这项回顾性研究中,一组250次CMR扫描和T1映射(3T,MOLLI5(3)3,收缩后含水层),分为推导和验证队列。左心室血池的固有T1时间(T1native,midLV)与24小时内(Hct24h)抽血的Hct水平相关,并通过线性回归得出Hctsyn的计算公式。
结果:在派生队列中(n=167),Hct24h与T1native表现出良好的关联,midLV(r=-0.711,p<0.001)。得到的回归方程为Hctsyn=1/T1native,中型LV*1355.52-0.310。在验证队列中(n=83),Hctsyn和Hct24h表现出良好的相关性(r=0.726,p<0.001),而ECVsyn,与ECV24h表现出良好的相关性(r=0.940,p<0.001)。ECVsyn的最小偏倚为0.28%,错误分类率(8.8%)与重复Hct测量引入的变异性相当(错误分类为7.5%)。在我们的队列中应用已发布的公式导致高达60%的错误分类。
结论:我们提供了在3T扫描仪上从天然血液T1估算Hctsyn的公式。ECVsyn的测量误差较低,可与常规Hct的重测变异性引起的误差相媲美。应使用特定于扫描仪和序列的公式。