Structure-sensitive quantitative MR imaging of renal mechanical properties: Combined anisotropic MR elastography and diffusion tensor imaging for the assessment of renal function

磁共振弹性成像（MRE）可以对体内组织的粘弹性特性进行无创表征，它是一种成熟的方法，已应用于肝纤维化分期、肿瘤分级等领域。在该项目中，将联合多频MRE （MMRE）和弥散张量成像（DTI）用于肾功能的机械评估。该项目旨在首次在充分考虑各向异性的情况下，研究体内天然肾脏的力学特性。各向异性是肾脏的一个关键特征，因为肾脏沿亨利袢呈放射状取向，聚集了小管和维管束。该MRE/DTI技术将首先在离体组织样本中进行验证，然后在健康志愿者中进行测试，最后应用于慢性肾脏疾病（CKD）患者。拟建项目分为以下工作包：(1)在慈善慈善会CCM放射科临床MRI扫描仪上实施MMRE/DTI联合患者激活呼吸门控系统和自动气动执行器。(2) mre /DTI联合应用于离体猪肾琼脂糖凝胶包埋的验证。(3)数据后处理和各向异性反演方法发展。(4)将MMRE/DTI联合技术应用于健康志愿者肾脏，建立肾皮质、髓质、肾门等区域各向异性粘弹性参数的参考值。(5) CKD患者的前期研究及各向异性粘弹性参数与临床数据的相关性。我们的组合MMRE/DTI将提供全弹性张量的恢复，从而提供各向异性材料的全面力学描述。这项技术可以深入了解与纤维化和灌注相关的肾脏硬度变化。mre /DTI联合检测的肾脏力学特性可作为检测CKD患者肾功能不全的新的定量成像工具。

Magnetic Resonance Elastography (MRE) allows non-invasive characterization of the viscoelastic properties of tissue in vivo, it is a well established method which has been applied in areas such as liver fibrosis staging, tumor grading, etc. In the proposed project, combined multifrequency MRE (MMRE) and diffusion tensor imaging (DTI) will be developed for the mechanical assessment of renal function. The project aims to investigate, for the first time, the mechanical properties of native kidneys in vivo taking full consideration of anisotropy which is a key feature in kidney due to the radially oriented architecture along the Henle loops, collecting tubules and vascular bundles. This proposed MRE/DTI technique will be firstly validated in ex vivo tissue sample, then tested in healthy volunteers and finally applied to patients with chronic kidney disease (CKD). The proposed project is divided into the following work packages: (1) Implementation of combined MMRE/DTI together with the patient-activated respiratory gating system and automated pneumatic actuator on a clinical MRI scanner of the Department of Radiology, Charité CCM. (2) Validation of combined MMRE/DTI on ex vivo porcine kidney embedded in agarose gel. (3) Method development in data post-processing and anisotropic inversion. (4) Application of the combined MMRE/DTI techniques to the kidneys in healthy volunteers and establish reference values for anisotropic viscoelastic parameters for regions such as renal cortex, medulla and hilus. (5) Pilot study in patients with CKD and correlation of anisotropic viscoelastic parameters to clinical data. Our combined MMRE/DTI will provide the recovery of the full elasticity tensor which offers a comprehensive mechanical description of anisotropic materials. This technique may bring insights into fibrosis and perfusion related renal stiffness changes. The renal mechanical properties obtained from combined MMRE/DTI could be used in the future as new quantitative imaging maker for detecting renal dysfunction in patients CKD.