Modified look-locker inversion recovery T1 mapping indices: assessment of accuracy and reproducibility between magnetic resonance scanners.
Modified look-locker inversion recovery T1 mapping indices: assessment of accuracy and reproducibility between magnetic resonance scanners.
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DOI：
10.1186/1532-429x-15-64
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发表时间：
2013-07-26
期刊：
影响因子：
--
通讯作者：
Liu S
中科院分区：
文献类型：
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作者：
Raman FS;Kawel-Boehm N;Gai N;Freed M;Han J;Liu CY;Lima JA;Bluemke DA;Liu S
心血管磁共振T1标测指标，如T1时间和分割系数(λ)，已显示出评估弥漫性心肌纤维化的潜力。本研究的目的是调查扫描仪和场强的变化如何影响T1标测指数的准确性和精密度/重复性。CMR研究在两台1.5T和三台3T扫描仪上进行。制作8个体模，模拟增强前后心肌和血液在1.5T和3T的T1/T2。用MOLLI进行T1标测，模拟心率为40~100 /min。反转恢复自旋回波(IR-SE)是测定T1的参考标准。准确度定义为Molli和IR-SE之间的百分比误差，扫描/再扫描重复性定义为重复Molli扫描之间的相对百分比平均差异。采用ΔR1型心肌模型/ΔR1型血液模型计算分割系数。使用广义线性混合模型比较T1和λ在不同场强、不同扫描仪和不同检查方案下的准确性和精密度/重复性。磁场强度显著影响Molli T1的准确度(1.5T的误差为6.3%，3T，p<；0.001的误差为10.8%)，但对λ的准确度没有影响(1.5T的误差为8.8%，3T的误差为8.0%，p=0.11)。Molli的分割系数在两个1.5T扫描仪之间没有差异(47.2%比47.9%，p=0.016)，在三个3T扫描仪中只有微小的差异(49.2%比49.8%比49.9%，p=0.016)。分割系数在精确度方面的百分比误差(更好的扫描/再扫描重复性)也显著低于单个T1值的测量(λ为3.6%，而T1值为4.3%-4.8%，大约是血液和心肌值的前后)。根据体模研究，在不同的MR扫描仪中，使用Molli的T1误差在6%-14%之间，而分割系数的误差较小(6%-10%)。与绝对T1次相比，分配系数在不同平台和场强之间的变异性较小，精度较高。
Cardiovascular magnetic resonance (CMR) T1 mapping indices, such as T1 time and partition coefficient (λ), have shown potential to assess diffuse myocardial fibrosis. The purpose of this study was to investigate how scanner and field strength variation affect the accuracy and precision/reproducibility of T1 mapping indices. CMR studies were performed on two 1.5T and three 3T scanners. Eight phantoms were made to mimic the T1/T2 of pre- and post-contrast myocardium and blood at 1.5T and 3T. T1 mapping using MOLLI was performed with simulated heart rate of 40-100 bpm. Inversion recovery spin echo (IR-SE) was the reference standard for T1 determination. Accuracy was defined as the percent error between MOLLI and IR-SE, and scan/re-scan reproducibility was defined as the relative percent mean difference between repeat MOLLI scans. Partition coefficient was estimated by ΔR1myocardium phantom/ΔR1blood phantom. Generalized linear mixed model was used to compare the accuracy and precision/reproducibility of T1 and λ across field strength, scanners, and protocols. Field strength significantly affected MOLLI T1 accuracy (6.3% error for 1.5T vs. 10.8% error for 3T, p<0.001) but not λ accuracy (8.8% error for 1.5T vs. 8.0% error for 3T, p=0.11). Partition coefficients of MOLLI were not different between two 1.5T scanners (47.2% vs. 47.9%, p=0.13), and showed only slight variation across three 3T scanners (49.2% vs. 49.8% vs. 49.9%, p=0.016). Partition coefficient also had significantly lower percent error for precision (better scan/re-scan reproducibility) than measurement of individual T1 values (3.6% for λ vs. 4.3%-4.8% for T1 values, approximately, for pre/post blood and myocardium values). Based on phantom studies, T1 errors using MOLLI ranged from 6-14% across various MR scanners while errors for partition coefficient were less (6-10%). Compared with absolute T1 times, partition coefficient showed less variability across platforms and field strengths as well as higher precision.