Department of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.
Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
Magn Reson Med. 2019 May;81(5):3192-3201. doi: 10.1002/mrm.27636. Epub 2018 Dec 18.
To develop a gadolinium-free cardiac MR technique that simultaneously exploits native T and magnetization transfer (MT) contrast for the imaging of myocardial infarction.
A novel hybrid T one and magnetization transfer (HYTOM) method was developed based on the modified look-locker inversion recovery (MOLLI) sequence, with a train of MT-prep pulses placed before the balanced SSFP (bSSFP) readout pulses. Numerical simulations, based on Bloch-McConnell equations, were performed to investigate the effects of MT induced by (1) the bSSFP readout pulses, and (2) the MT-prep pulses, on the measured, "apparent," native T values. The HYTOM method was then tested on 8 healthy adult subjects, 6 patients, and a swine with prior myocardial infarction (MI). The resulting imaging contrast between normal myocardium and infarcted tissues was compared with that of MOLLI. Late gadolinium enhancement (LGE) images were also obtained for infarct assessment in patients and swine.
Numerical simulation and in vivo studies in healthy volunteers demonstrated that MT effects, resulting from on-resonance bSSFP excitation pulses and off-resonance MT-prep pulses, reduce the measured T in both MOLLI and HTYOM. In vivo studies in patients and swine showed that the HYTOM sequence can identify locations of MI, as seen on LGE. Furthermore, the HYTOM method yields higher myocardium-to-scar contrast than MOLLI (contrast-to-noise ratio: 7.33 ± 1.67 vs. 3.77 ± 0.66, P < 0.01).
The proposed HYTOM method simultaneously exploits native T and MT contrast and significantly boosts the imaging contrast for myocardial infarction.
开发一种无需钆的心脏磁共振技术，该技术可同时利用组织内固有 T 值和磁化转移（MT）对比来对心肌梗死进行成像。
基于改良 Look-Locker 反转恢复（MOLLI）序列，我们开发了一种新型的混合 T1 和磁化转移（HYTOM）方法，在平衡稳态自由进动（bSSFP）读出脉冲之前放置一系列 MT 预脉冲。基于 Bloch-McConnell 方程的数值模拟，研究了 MT 对（1）bSSFP 读出脉冲和（2）MT 预脉冲引起的测量“表观”固有 T 值的影响。然后，我们在 8 名健康成年人、6 名患者和 1 只患有先前心肌梗死（MI）的猪身上测试了 HYTOM 方法。将正常心肌与梗死组织之间的成像对比与 MOLLI 进行了比较。还在患者和猪身上获得了晚期钆增强（LGE）图像以评估梗死情况。
数值模拟和健康志愿者的体内研究表明，来自共振 bSSFP 激励脉冲和非共振 MT 预脉冲的 MT 效应降低了 MOLLI 和 HTYOM 中测量的 T 值。在患者和猪的体内研究表明，HYTOM 序列可以识别 LGE 所见的 MI 位置。此外，与 MOLLI 相比，HYTOM 方法可产生更高的心肌与瘢痕的对比度（对比噪声比：7.33±1.67 比 3.77±0.66，P<0.01）。
所提出的 HYTOM 方法同时利用组织内固有 T 值和 MT 对比，显著提高了心肌梗死的成像对比度。
