BACKGROUND In-vivo cardiovascular magnetic resonance (CMR) diffusion tensor imaging (DTI) allows imaging of alterations of cardiac fiber architecture in diseased hearts. Cardiac amyloidosis (CA) causes myocardial infiltration of misfolded proteins with unknown consequences for myocardial microstructure. This study applied CMR DTI in CA to assess microstructural alterations and their consequences for myocardial function compared to healthy controls. METHODS Ten patients with CA (8 AL, 2 ATTR) and ten healthy controls were studied using a diffusion-weighed second-order motion-compensated spin-echo sequence at 1.5 T. Additionally, left ventricular morphology, ejection fraction, strain and native T1 values were obtained in all subjects. In CA patients, T1 mapping was repeated after the administration of gadolinium for extracellular volume fraction (ECV) calculation. CMR DTI analysis was performed to yield the scalar diffusion metrics mean diffusivity (MD) and fractional anisotropy (FA) as well as the characteristics of myofiber orientation including helix, transverse and E2A sheet angle (HA, TA, E2A). RESULTS MD and FA were found to be significantly different between CA patients and healthy controls (MD 1.77 ± 0.17 10- 3 vs 1.41 ± 0.07 10- 3 mm2/s, p <  0.001; FA 0.25 ± 0.04 vs 0.35 ± 0.03, p <  0.001). MD demonstrated an excellent correlation with native T1 (r = 0.908, p <  0.001) while FA showed a significant correlation with ECV in the CA population (r = - 0.851, p <  0.002). HA exhibited a more circumferential orientation of myofibers in CA patients, in conjunction with a higher TA standard deviation and a higher absolute E2A sheet angle. The transmural HA slope was found to be strongly correlated with the global longitudinal strain (r = 0.921, p < 0.001). CONCLUSION CMR DTI reveals significant alterations of scalar diffusion metrics in CA patients versus healthy controls. Elevated MD and lower FA values indicate myocardial disarray with higher diffusion in CA that correlates well with native T1 and ECV measures. In CA patients, CMR DTI showed pronounced circumferential orientation of the myofibers, which may provide the rationale for the reduction of global longitudinal strain that occurs in amyloidosis patients. Accordingly, CMR DTI captures specific features of amyloid infiltration, which provides a deeper understanding of the microstructural consequences of CA.

中文翻译：

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使用心血管磁共振扩散张量成像表征淀粉样变性的心脏受累。


背景技术体内心血管磁共振（CMR）扩散张量成像（DTI）允许对患病心脏中的心肌纤维结构的改变进行成像。心脏淀粉样变性 (CA) 会导致错误折叠蛋白的心肌浸润，对心肌微观结构的影响未知。本研究在 CA 中应用 CMR DTI 来评估与健康对照相比的微结构改变及其对心肌功能的影响。方法 使用 1.5 T 的扩散称重二阶运动补偿自旋回波序列对 10 名 CA 患者（8 AL，2 ATTR）和 10 名健康对照进行研究。此外，还研究了左心室形态、射血分数、应变和天然 T1所有受试者均获得了数值。在CA患者中，在施用钆后重复T1标测以计算细胞外体积分数(ECV)。进行 CMR DTI 分析以获得标量扩散指标平均扩散率 (MD) 和分数各向异性 (FA) 以及肌纤维取向的特征，包括螺旋、横向和 E2A 片角（HA、TA、E2A）。结果 CA 患者和健康对照之间的 MD 和 FA 存在显着差异（MD 1.77 ± 0.17 10- 3 vs 1.41 ± 0.07 10- 3 mm2/s，p < 0.001；FA 0.25 ± 0.04 vs 0.35 ± 0.03，p < 0.001）。 MD 与本地 T1 表现出极好的相关性 (r = 0.908，p < 0.001)，而 FA 在 CA 人群中表现出与 ECV 显着相关性 (r = - 0.851，p < 0.002)。 CA 患者的 HA 表现出更圆周方向的肌纤维，同时具有更高的 TA 标准偏差和更高的绝对 E2A 片角。发现透壁 HA 斜率与整体纵向应变密切相关（r = 0.921，p < 0.001）。 结论 CMR DTI 揭示了 CA 患者与健康对照相比标量扩散指标的显着变化。 MD 值升高和 FA 值降低表明心肌紊乱，CA 中弥散度较高，与天然 T1 和 ECV 测量值密切相关。在 CA 患者中，CMR DTI 显示肌纤维明显的圆周方向，这可能为减少淀粉样变性患者中发生的整体纵向应变提供依据。因此，CMR DTI 捕获了淀粉样蛋白浸润的特定特征，从而可以更深入地了解 CA 的微观结构后果。