Annu Int Conf IEEE Eng Med Biol Soc. 2022 Jul;2022:1690-1693. doi: 10.1109/EMBC48229.2022.9871870.
Magnetic Resonance Imaging (MRI) is the clinical gold standard for the assessment of myocardial viability but requires injection of exogenous gadolinium-based contrast agents. Recently, T-mapping has been proposed as a fully non-invasive alternative for imaging myocardial fibrosis without the need for contrast agent injection. However, its applicability at high fields is hindered by susceptibility to MRI system imperfections, such as inhomogeneities in the B and B fields. In this work we propose a single breath-hold ECG-triggered single-shot bSSFP sequence to enable T-mapping in vivo at 3T. Adiabatic T preparations are evaluated to reduce B and B sensitivity in comparison with conventional spin-lock (SL) modules. Numerical Bloch simulations were performed to identify optimal parameters for the adiabatic pulses. Experiments yield T values in the myocardium equal to 48.13±54.08 ms for the best adiabatic preparation and 16.01±20.75 ms for the reference non-adiabatic SL, with 26.91% against 89.74% relative difference in T values across two shimming conditions. Both phantom and in vivo measurements show increased myocardium/blood contrast and improved resilience against system imperfections compared to non-adiabatic T preparations, enabling the use at 3T. Clinical relevance- Adiabatically-prepared T-mapping sequences form a promising candidate for non-contrast evaluation of ischemic and non-ischemic cardiomyopathies at 3T.
磁共振成像（MRI）是评估心肌活力的临床金标准，但需要注射外源性钆基造影剂。最近，T 映射已被提议作为一种完全非侵入性的替代方法，用于成像心肌纤维化，而无需注射造影剂。然而，由于对 MRI 系统不完善的敏感性，如 B 和 B 场的不均匀性，其在高场中的应用受到限制。在这项工作中，我们提出了一种单呼吸门控 ECG 触发单次激发 bSSFP 序列，以实现 3T 下的体内 T 映射。评估了绝热 T 准备，以减少与传统自旋锁定（SL）模块相比的 B 和 B 敏感性。进行了数值布洛赫模拟，以确定绝热脉冲的最佳参数。实验在心肌中产生 T 值，最佳绝热制备的 T 值为 48.13±54.08ms，参考非绝热 SL 的 T 值为 16.01±20.75ms，两种匀场条件下 T 值的相对差异为 26.91%对 89.74%。与非绝热 T 准备相比，无论是在体模还是体内测量，都显示出心肌/血液对比度增加，对系统不完善的弹性提高，从而能够在 3T 下使用。临床意义- 绝热 T 映射序列为在 3T 下非对比评估缺血性和非缺血性心肌病提供了一种很有前途的候选方法。
