North West Heart Centre and The Transplant Centre, University Hospitalof South Manchester, Wythenshawe Hospital, Manchester, United Kingdom.
Circ Cardiovasc Imaging. 2013 May 1;6(3):373-83. doi: 10.1161/CIRCIMAGING.112.000192. Epub 2013 Apr 3.
Extracellular matrix expansion is a key element of ventricular remodeling and a potential therapeutic target. Cardiovascular magnetic resonance (CMR) T1-mapping techniques are increasingly used to evaluate myocardial extracellular volume (ECV); however, the most widely applied methods are without histological validation. Our aim was to perform comprehensive validation of (1) dynamic-equilibrium CMR (DynEq-CMR), where ECV is quantified using hematocrit-adjusted myocardial and blood T1 values measured before and after gadolinium bolus; and (2) isolated measurement of myocardial T1, used as an ECV surrogate.
Whole-heart histological validation was performed using 96 tissue samples, analyzed for picrosirius red collagen volume fraction, obtained from each of 16 segments of the explanted hearts of 6 patients undergoing heart transplantation who had prospectively undergone CMR before transplantation (median interval between CMR and transplantation, 29 days). DynEq-CMR-derived ECV was calculated from T1 measurements made using a modified Look-Locker inversion recovery sequence before and 10 and 15 minutes post contrast. In addition, ECV was measured 2 to 20 minutes post contrast in 30 healthy volunteers. There was a strong linear relationship between DynEq-CMR-derived ECV and histological collagen volume fraction (P<0.001; within-subject: r=0.745; P<0.001; r(2)=0.555 and between-subject: r=0.945; P<0.01; r(2)=0.893; for ECV calculated using 15-minute postcontrast T1). Correlation was maintained throughout the entire heart. Isolated postcontrast T1 measurement showed significant within-subject correlation with histological collagen volume fraction (r=-0.741; P<0.001; r(2)=0.550 for 15-minute postcontrast T1), but between-subject correlations were not significant. DynEq-CMR-derived ECV varied significantly according to contrast dose, myocardial region, and sex.
DynEq-CMR-derived ECV shows a good correlation with histological collagen volume fraction throughout the whole heart. Isolated postcontrast T1 measurement is insufficient for ECV assessment.
细胞外基质扩张是心室重构的一个关键因素，也是潜在的治疗靶点。心血管磁共振（CMR）T1 映射技术越来越多地用于评估心肌细胞外容积（ECV）；然而，应用最广泛的方法没有经过组织学验证。我们的目的是全面验证（1）使用全血校正的心肌和血 T1 值测量值，在钆造影剂团注前后测量，计算得到的动态平衡 CMR（DynEq-CMR）；以及（2）心肌 T1 的独立测量，作为 ECV 的替代指标。
使用来自 6 名接受心脏移植患者的 16 个节段的 96 个组织样本进行全心脏组织学验证，这些患者在移植前前瞻性地进行了 CMR（CMR 和移植之间的中位间隔时间为 29 天）。在对比剂团注前和 10 分钟及 15 分钟后使用改良 Look-Locker 反转恢复序列测量 T1 值，计算 DynEq-CMR 衍生的 ECV。此外，在 30 名健康志愿者中，在对比剂团注后 2 至 20 分钟测量 ECV。DynEq-CMR 衍生的 ECV 与组织学胶原容积分数之间存在很强的线性关系（P<0.001；个体内：r=0.745；P<0.001；r(2)=0.555；个体间：r=0.945；P<0.01；r(2)=0.893；使用 15 分钟对比后 T1 计算的 ECV）。相关性在整个心脏中保持一致。心肌组织学胶原容积分数与独立的对比后 T1 测量值呈显著的个体内相关性（r=-0.741；P<0.001；r(2)=0.550 用于 15 分钟对比后 T1），但个体间相关性不显著。DynEq-CMR 衍生的 ECV 根据对比剂剂量、心肌区域和性别而显著变化。
DynEq-CMR 衍生的 ECV 在整个心脏中与组织学胶原容积分数有很好的相关性。独立的对比后 T1 测量不足以评估 ECV。
