BACKGROUND Endogenous contrast T1ρ cardiovascular magnetic resonance (CMR) can detect scar or infiltrative fibrosis in patients with ischemic or non-ischemic cardiomyopathy. Existing 2D T1ρ techniques have limited spatial coverage or require multiple breath-holds. The purpose of this project was to develop an accelerated, free-breathing 3D T1ρ mapping sequence with whole left ventricle coverage using a multicoil, compressed sensing (CS) reconstruction technique for rapid reconstruction of undersampled k-space data. METHODS We developed a cardiac- and respiratory-gated, free-breathing 3D T1ρ sequence and acquired data using a variable-density k-space sampling pattern (A = 3). The effect of the transient magnetization trajectory, incomplete recovery of magnetization between T1ρ-preparations (heart rate dependence), and k-space sampling pattern on T1ρ relaxation time error and edge blurring was analyzed using Bloch simulations for normal and chronically infarcted myocardium. Sequence accuracy and repeatability was evaluated using MnCl2 phantoms with different T1ρ relaxation times and compared to 2D measurements. We further assessed accuracy and repeatability in healthy subjects and compared these results to 2D breath-held measurements. RESULTS The error in T1ρ due to incomplete recovery of magnetization between T1ρ-preparations was T1ρhealthy = 6.1% and T1ρinfarct = 10.8% at 60 bpm and T1ρhealthy = 13.2% and T1ρinfarct = 19.6% at 90 bpm. At a heart rate of 60 bpm, error from the combined effects of readout-dependent magnetization transients, k-space undersampling and reordering was T1ρhealthy = 12.6% and T1ρinfarct = 5.8%. CS reconstructions had improved edge sharpness (blur metric = 0.15) compared to inverse Fourier transform reconstructions (blur metric = 0.48). There was strong agreement between the mean T1ρ estimated from the 2D and accelerated 3D data (R2 = 0.99; P < 0.05) acquired on the MnCl2 phantoms. The mean R1ρ estimated from the accelerated 3D sequence was highly correlated with MnCl2 concentration (R2 = 0.99; P < 0.05). 3D T1ρ acquisitions were successful in all human subjects. There was no significant bias between undersampled 3D T1ρ and breath-held 2D T1ρ (mean bias = 0.87) and the measurements had good repeatability (COV2D = 6.4% and COV3D = 7.1%). CONCLUSIONS This is the first report of an accelerated, free-breathing 3D T1ρ mapping of the left ventricle. This technique may improve non-contrast myocardial tissue characterization in patients with heart disease in a scan time appropriate for patients.

中文翻译：

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使用多线圈压缩感测加速自由呼吸的3DT1ρ心血管磁共振。

背景技术内源性对比剂T1ρ心血管磁共振（CMR）可以检测出缺血性或非缺血性心肌病患者的瘢痕或浸润性纤维化。现有的2DT1ρ技术具有有限的空间覆盖范围或需要多次屏气。该项目的目的是使用多线圈，压缩感测（CS）重建技术，开发一个可加速，自由呼吸的3DT1ρ映射序列，以覆盖整个左心室，以快速重建欠采样的k空间数据。方法我们开发了心脏和呼吸门控的，自由呼吸的3DT1ρ序列，并使用可变密度k空间采样模式（A = 3）采集了数据。瞬态磁化轨迹的影响，T1ρ准备之间的磁化不完全恢复（心率依赖性），并使用Bloch模拟分析了正常和慢性梗死心肌的T1ρ弛豫时间误差和边缘模糊的k空间采样模式。使用具有不同T1ρ弛豫时间的MnCl2体模评估序列的准确性和可重复性，并将其与2D测量值进行比较。我们进一步评估了健康受试者的准确性和可重复性，并将这些结果与二维屏气测量结果进行了比较。结果由于T1ρ制剂之间磁化强度未完全恢复，导致T1ρ的误差为60 bpm时T1ρhealthy= 6.1％和T1ρ梗塞= 10.8％，而90 bpm时T1ρhealthy= 13.2％和T1ρ梗塞= 19.6％。在60 bpm的心率下，与读出有关的磁化瞬变，k空间欠采样和重新排序的综合作用所引起的误差为T1ρhealthy= 12.6％和T1ρ梗塞= 5.8％。与傅里叶逆变换（模糊度= 0.48）相比，CS重建具有更高的边缘清晰度（模糊度= 0.15）。在MnCl2体模上，根据2D估计的平均T1ρ与加速的3D数据（R2 = 0.99； P <0.05）之间存在强烈的一致性。从加速的3D序列估算的平均R1ρ与MnCl2浓度高度相关（R2 = 0.99； P <0.05）。在所有人类受试者中3DT1ρ采集均成功。欠采样的3DT1ρ和屏气的2DT1ρ之间没有显着偏差（平均偏差= 0.87），并且测量结果具有良好的重复性（COV2D = 6.4％和COV3D = 7.1％）。结论这是左心室加速，自由呼吸的3DT1ρ作图的第一个报告。