Development and evaluation of cardiac sodium (23Na) MR imaging to quantify myocardial sodium accumulation in vivo in humans

心血管疾病是全世界死亡的主要原因。盐（NaCl）摄入量增加是心血管疾病发展的一个重要风险因素。最近使用钠（23 Na）磁共振成像（MRI）的研究表明，人体体内皮肤和肌肉组织中存在病理生理学相关的钠蓄积，这与高血压的发生有关。这发生在有心血管风险的患者中，如糖尿病患者和透析患者。在慢性肾脏病（CKD）患者中，组织钠浓度升高也被确定为左心室肥大的最重要因素，是心脏病发病率和死亡率的独立风险因素。目前尚不清楚组织钠浓度的增加是否也直接发生在心脏中。为了首次量化CKD患者的心脏组织钠浓度，将在MR物理学家和医生之间的密切跨学科合作下实施心脏23 Na MRI，并优化临床应用。第一步是开发7特斯拉下心脏23 Na MRI的新的有效测量技术，该技术允许在临床可接受的测量时间（< 15分钟）内对心肌中的组织钠浓度进行可重复的定量。此外，将开发获取技术，提供有关心肌中钠离子生理环境的信息。此外，将开发和实施用于心脏和呼吸运动以及用于校正部分容积效应的稳健校正方法。通过使用双谐振线圈，将以时间交错方式采集23 Na和1H MRI的数据。该数据的几乎同时记录旨在一方面实现更短的测量时间，另一方面改进运动伪影的校正。应使用来自所有呼吸相位的数据来提高心脏23 Na MRI的时间效率。为此，要计算所谓的“运动矢量场”，其允许可变形配准。这些将直接集成到图像重建中，以便生成运动校正的23 Na MRI数据。第二步，新的采集技术将用于第一次临床试验。我们计划在血液透析治疗前后使用心脏23 Na-MRI检查透析患者。我们假设这些患者在心肌中积累钠，并且这种过量的钠与心脏结构紊乱相关，从而导致终末器官损伤。将来，开发的方法可用于特异性识别慢性心肌钠超载患者，并提供个性化治疗，例如通过调整透析处方。

Cardiovascular diseases are the leading cause of death worldwide. Increased salt (NaCl) intake is a significant risk factor for the development of cardiovascular diseases. Recent studies using sodium (23Na) magnetic resonance imaging (MRI) have shown pathophysiologically relevant sodium accumulation in skin and muscle tissue in vivo in humans, which was linked to the development of hypertension. This occurred in at-risk cardiovascular patients such as diabetics and dialysis patients. In patients with chronic kidney disease (CKD), increased tissue sodium concentrations were also identified as the most important factor for left ventricular hypertrophy, an independent risk factor for cardiac morbidity and mortality. Whether increased tissue sodium concentrations also occur directly in the heart is not yet known.In order to quantify the cardiac tissue sodium concentration for the first time in CKD patients, cardiac 23Na MRI will be implemented in close interdisciplinary cooperation between MR physicists and physicians, and optimized for clinical application. The first step is to develop new efficient measurement techniques for cardiac 23Na MRI at 7 Tesla, which allow reproducible quantification of tissue sodium concentration in the myocardium within clinically acceptable measuring time (< 15 min). In addition, acquisition techniques will be developed that provide information about the physiological environment of sodium ions in the myocardium. Moreover, robust correction methods for cardiac and respiratory motion, as well as for correcting partial volume effects, will be developed and implemented. By using double-resonant coils, data for 23Na and 1H MRI will be acquired in a time-interleaved manner. The almost simultaneous recording of this data is intended to enable shorter measurement times on the one hand and an improved correction of motion artifacts on the other. Data from all respiratory phases should be used to increase the temporal efficiency of cardiac 23Na MRI. For this purpose, so-called "motion vector fields" are to be calculated, which allow a deformable registration. These will be integrated directly into the image reconstruction so that motion-corrected 23Na MRI data can be generated. In the second step, the new acquisition techniques will be used in the first clinical trials. We plan to examine dialysis patients before and after hemodialysis treatment using cardiac 23Na-MRI. We assume that these patients accumulate sodium in the myocardium and that this excess sodium is associated with cardiac structural disorder and thus end organ damage. In the future, the methods developed could be used to specifically identify patients with chronic myocardial sodium overload and to provide personalized therapy, e.g. by adjusting dialysis prescription.