Xanthis Christos G, Bidhult Sebastian, Greiser Andreas, Chow Kelvin, Thompson Richard B, Arheden Håkan, Aletras Anthony H
Lund University, Department of Clinical Sciences Lund, Clinical Physiology, Skåne University Hospital, Lund, Sweden; Laboratory of Computing and Medical Informatics, School of Medicine, Aristotle University of Thessaloniki, Greece.
Lund University, Department of Clinical Sciences Lund, Clinical Physiology, Skåne University Hospital, Lund, Sweden; Faculty of Engineering, Lund University, Department of Biomedical Engineering, Lund, Sweden.
Magn Reson Imaging. 2018 May;48:96-106. doi: 10.1016/j.mri.2017.12.020. Epub 2017 Dec 26.
Quantitative cardiovascular Magnetic Resonance Imaging techniques are gaining wide acceptance within the MR community due to their potential to diagnose non-localized disease, guide therapy and improve patient outcome. During the last decade, there has been an increasing interest for developing new techniques that allow for simultaneous quantification of both T1 and T2 maps of myocardium. Newer studies demonstrated that the incorporation of MRI simulations could yield similar results to conventional mapping techniques in the myocardium. However, these simulation-based quantitative MR techniques usually compare the in-vivo T1 estimates against less accurate T1 techniques, whereas they present inconsistencies between simulation studies, phantom and in-vivo measurements. Moreover, these studies do not investigate the effect of Magnetization Transfer on the myocardial T1 and T2 estimates but are usually validated on phantoms where the MT effect is small. The main aim of this study was to perform simultaneous mapping of the native T1 and T2 of the myocardium through the utilization of a modified MOLLI pulse sequence and the incorporation of advanced MR simulations through the SQUAREMR framework. A second aim of this study was to investigate the effect of MT on simulation-based quantitative MR techniques. A conventional MOLLI pulse sequence was modified so as to present combined high T2 sensitivity and low MT effect. The new technique was applied in healthy volunteers and demonstrated an improved T1 accuracy compared to the conventional MOLLI and a T2 accuracy similar to the one provided by the T2prep-bSSFP method. The effect of MT on T1 and T2 estimates was also investigated in the current study. Phantoms with an increasing MT effect as well as phantoms without an MT effect were included in this work whereas several variants of the modified-MOLLI that introduce different amounts of T2 modulation on the MR signal and induce different MT effects were applied on the phantoms. The proposed simulation-based quantitative MR technique for simultaneous T1 and T2 mapping of the myocardium does not require the incorporation of a complicated custom designed pulse sequence and does not require a complicated reconstruction workflow. Moreover, the current study demonstrates for the first time that MT plays an important role in the simulation-based quantitative MR studies and points out the necessity of incorporating the study of MT in future techniques.
定量心血管磁共振成像技术因其在诊断非局限性疾病、指导治疗和改善患者预后方面的潜力，在磁共振成像领域正获得广泛认可。在过去十年中，人们对开发能够同时定量心肌T1和T2图谱的新技术越来越感兴趣。最新研究表明，纳入MRI模拟在心肌中可产生与传统映射技术相似的结果。然而，这些基于模拟的定量磁共振技术通常将体内T1估计值与不太准确的T1技术进行比较，而且它们在模拟研究、体模和体内测量之间存在不一致。此外，这些研究没有研究磁化传递对心肌T1和T2估计值的影响，而是通常在磁化传递效应较小的体模上进行验证。本研究的主要目的是通过利用改进的MOLLI脉冲序列并通过SQUAREMR框架纳入先进的磁共振模拟，对心肌的天然T1和T2进行同步映射。本研究的第二个目的是研究磁化传递对基于模拟的定量磁共振技术的影响。对传统的MOLLI脉冲序列进行了修改，使其具有高T2灵敏度和低磁化传递效应的组合。新技术应用于健康志愿者，与传统MOLLI相比，T1准确性有所提高，T2准确性与T2prep-bSSFP方法提供的准确性相似。本研究还研究了磁化传递对T1和T2估计值的影响。这项工作纳入了磁化传递效应不断增加的体模以及没有磁化传递效应的体模，同时将引入不同程度的T2调制到磁共振信号并诱导不同磁化传递效应的几种改进MOLLI变体应用于体模。所提出的用于心肌T1和T2同步映射的基于模拟的定量磁共振技术不需要纳入复杂的定制设计脉冲序列，也不需要复杂的重建工作流程。此外，本研究首次表明磁化传递在基于模拟的定量磁共振研究中起着重要作用，并指出在未来技术中纳入磁化传递研究的必要性。
