PDF(Pubmed)
Abstract：
Introduction: Magnetic resonance elastography (MRE) is a non-invasive method to quantify biomechanical properties of human tissues. It has potential in diagnosis and monitoring of kidney disease, if established in clinical practice. The interplay of flow and volume changes in renal vessels, tubule, urinary collection system and interstitium is complex, but physiological ranges of in vivo viscoelastic properties during fasting and hydration have never been investigated in all gross anatomical segments simultaneously. Method: Ten healthy volunteers underwent two imaging sessions, one following a 12-hour fasting period and the second after a drinking challenge of >10 mL per kg body weight (60-75 min before the second examination). High-resolution renal MRE was performed using a novel driver with rotating eccentric mass placed at the posterior-lateral wall to couple waves (50 Hz) to the kidney. The biomechanical parameters, shear wave speed (cs in m/s), storage modulus (Gd in kPa), loss modulus (Gl in kPa), phase angle (Υ=2πatanGlGd) and attenuation (α in 1/mm) were derived. Accurate separation of gross anatomical segments was applied in post-processing (whole kidney, cortex, medulla, sinus, vessel). Results: High-quality shear waves coupled into all gross anatomical segments of the kidney (mean shear wave displacement: 163 ± 47 μm, mean contamination of second upper harmonics <23%, curl/divergence: 4.3 ± 0.8). Regardless of the hydration state, median Gd of the cortex and medulla (0.68 ± 0.11 kPa) was significantly higher than that of the sinus and vessels (0.48 ± 0.06 kPa), and consistently, significant differences were found in cs, Υ, and Gl (all p < 0.001). The viscoelastic parameters of cortex and medulla were not significantly different. After hydration sinus exhibited a small but significant reduction in median Gd by -0.02 ± 0.04 kPa (p = 0.01), and, consequently, the cortico-sinusoidal-difference in Gd increased by 0.04 ± 0.07 kPa (p = 0.05). Only upon hydration, the attenuation in vessels became lower (0.084 ± 0.013 1/mm) and differed significantly from the whole kidney (0.095 ± 0.007 1/mm, p = 0.01). Conclusion: High-resolution renal MRE with an innovative driver and well-defined 3D segmentation can resolve all renal segments, especially when including the sinus in the analysis. Even after a prolonged hydration period the approach is sensitive to small hydration-related changes in the sinus and in the cortico-sinusoidal-difference.
摘要：
简介：磁共振弹性成像（MRE）是一种量化人体组织生物力学特性的非侵入性方法。它具有诊断和监测肾脏疾病的潜力，如果在临床实践中确定。肾血管流量和体积变化的相互作用，细管,泌尿系统和间质是复杂的，但是，从未在所有大体解剖部分同时研究过禁食和水合过程中体内粘弹性的生理范围。方法：10名健康志愿者接受了两次影像学检查，在禁食12小时后，第二次在饮酒挑战>10mL/kg体重后（第二次检查前60-75分钟）。使用新型驱动器进行高分辨率肾脏MRE，该驱动器具有旋转的偏心质量，该偏心质量放置在后侧壁上以将波（50Hz）耦合到肾脏。生物力学参数，剪切波速(cs,m/s),储能模量（Gd，单位：kPa），损耗模量(Gl,kPa),得出相角(Y=2πatanGlGd)和衰减(α，单位为1/mm)。在后处理中应用了大体解剖段的精确分离(整个肾脏，皮质,髓质,鼻窦,船只)。结果：高质量的剪切波耦合到肾脏的所有大体解剖段（平均剪切波位移：163±47μm，二次谐波的平均污染<23%，卷曲/发散：4.3±0.8）。不管水合状态如何，皮质和髓质的中位数Gd（0.68±0.11kPa）明显高于窦和血管（0.48±0.06kPa），并且始终如一，CS存在显著差异，γ,和Gl(所有p<0.001)。皮质和髓质的粘弹性参数无明显差别。水化窦后，Gd中位数下降了-0.02±0.04kPa（p=0.01），and,因此,Gd的皮质正弦差增加了0.04±0.07kPa（p=0.05）。只有在水合时，血管中的衰减变得更低（0.084±0.0131/mm），并且与整个肾脏（0.095±0.0071/mm，p=0.01)。结论：具有创新驱动器和定义明确的3D分割的高分辨率肾MRE可以解析所有肾段，尤其是在分析中包括窦时。即使经过长时间的水合作用，该方法也对窦和皮质窦差中与水合作用相关的小变化敏感。
