Department of Medical Imaging, National Taiwan University Hospital, No.7, Chung-Shan South Road, Taipei, 100, Taiwan.
Department of Medical Imaging and Radiological Technology, Yuanpei University of Medical Technology, Hsinchu, Taiwan.
J Cardiovasc Magn Reson. 2020 Nov 30;22(1):77. doi: 10.1186/s12968-020-00689-x.
Cardiovascular magnetic resonance (CMR)-derived extracellular volume (ECV) requires a hematocrit (Hct) to correct contrast volume distributions in blood. However, the timely assessment of Hct can be challenging and has limited the routine clinical application of ECV. The goal of the present study was to evaluate whether ECV measurements lead to significant error if a venous Hct was unavailable on the day of CMR.
109 patients with CMR T1 mapping and two venous Hcts (Hct: a Hct from the day of CMR, and Hct: a Hct from a different day) were retrospectively identified. A synthetic Hct (Hct) derived from native blood T1 was also assessed. The study used two different ECV methods, (1) a conventional method in which ECV was estimated from native and postcontrast T1 maps using a region-based method, and (2) an inline method in which ECV was directly measured from inline ECV mapping. ECVs measured with Hct, Hct, and Hct were compared for each method, and the reference ECV (ECV) was defined using the Hct. The error between synthetic (ECV) and ECVwas analyzed for the two ECV methods.
ECV measured using Hct and Hct were significantly correlated with ECV for each method. No significant differences were observed between ECV and ECV measured with Hct (ECV; 28.4 ± 6.6% vs. 28.3 ± 6.1%, p = 0.789) and between ECV and ECV calculated with Hct (ECV; 28.4 ± 6.6% vs. 28.2 ± 6.2%, p = 0.45) using the conventional method. Similarly, ECV was not significantly different from ECV (28.5 ± 6.7% vs. 28.5 ± 6.2, p = 0.801) and ECV (28.5 ± 6.7% vs. 28.4 ± 6.0, p = 0.974) using inline method. ECV values revealed relatively large discrepancies in patients with lower Hcts compared with those with higher Hcts.
Venous Hcts measured on a different day from that of the CMR examination can still be used to measure ECV. ECV can provide an alternative method to quantify ECV without needing a blood sample, but significant ECV errors occur in patients with severe anemia.
心血管磁共振（CMR）衍生的细胞外容积（ECV）需要血细胞比容（Hct）来校正血液中的对比体积分布。然而，及时评估 Hct 可能具有挑战性，并且限制了 ECV 的常规临床应用。本研究的目的是评估如果在 CMR 当天无法获得静脉 Hct，ECV 测量是否会导致显著误差。
回顾性分析了 109 例接受 CMR T1 映射和两次静脉 Hct（Hct：CMR 当天的 Hct，Hct：不同日期的 Hct）的患者。还评估了源自天然血液 T1 的合成 Hct（Hct）。该研究使用了两种不同的 ECV 方法，（1）一种传统方法，其中使用基于区域的方法从天然和对比后 T1 图谱中估计 ECV，以及（2）一种内联方法，其中直接从内联 ECV 映射中测量 ECV。比较了两种方法中使用 Hct、Hct 和 Hct 测量的 ECV，并使用 Hct 定义参考 ECV（ECV）。分析了两种 ECV 方法中合成（ECV）和 ECV 之间的误差。
使用 Hct 和 Hct 测量的 ECV 与每种方法的 ECV 均呈显著相关。使用传统方法时，ECV 与 Hct 测量的 ECV（ECV；28.4±6.6%比 28.3±6.1%，p=0.789）和 Hct 计算的 ECV（ECV；28.4±6.6%比 28.2±6.2%，p=0.45）之间无显著差异。同样，ECV 与 ECV（28.5±6.7%比 28.5±6.2，p=0.801）和 ECV（28.5±6.7%比 28.4±6.0，p=0.974）之间无显著差异。与较高 Hct 的患者相比，较低 Hct 的患者的 ECV 值显示出较大的差异。
CMR 检查当天以外的日期测量的静脉 Hct 仍可用于测量 ECV。ECV 可以提供一种替代方法来定量 ECV，而无需血液样本，但在严重贫血的患者中会出现显著的 ECV 误差。
