Quantitative MRI and MR Elastography in Renal Transplants

肾移植是恢复肾功能的唯一方法。急性移植排斥反应的检测发生在所有肾移植受者中的35%，这是移植后早期阶段的主要挑战。急性排斥反应的特点是受者对供者肾脏产生强烈的免疫反应，通常进展为亚临床状态。早期发现急性排斥反应是迅速启动免疫抑制休克治疗以防止完全破坏移植的关键。有创活检是目前诊断急性排斥反应的参考标准。非侵入性生物标志物，如血清和尿液中的肌酐，已被证明仅在晚期才对结构性肾组织变化敏感，通常会推迟临床干预。相反，定量磁共振成像(QMRI)，包括通过动脉自旋标记(ASL)、血氧水平依赖(BOLD)MRI、弥散加权成像(DWI)和磁共振弹性成像(MRE)确定血流灌注，可以无创地评估活体肾移植的结构和功能特性。为此，将首次收集自体肾脏和移植肾脏的创新的qMRI和MRE参数，并进行测试，以用于临床评估疑似急性肾移植排斥反应的肾脏受者。为此，将对健康志愿者和活体供者移植前的天然肾脏、移植后的移植肾脏和发生急性移植排斥反应的受者进行ASL、BOLD-MRI、DWI和MRE检查。我们的方案有望通过对MRI定量数据的多参数分析，得出肾移植术后早期病理功能结构变化的结论，从而改善肾移植后急性排斥反应的治疗决策和临床处理。

Kidney transplantation is the only treatment that restores kidney function. The detection of acute transplant rejection, which occurs in 35% of all kidney recipients, is a major challenge during the early post-transplantation phase. Acute rejection is characterized by a strong immune response of the recipient against the donor kidney and often progresses subclinically. Early detection of acute rejection is essential for prompt initiation of immunosuppressive shock therapy to prevent complete transplant destruction. Invasive biopsy is the current reference standard for diagnosis of acute rejection. Noninvasive biomarkers such as creatinine from blood serum and urine output have been shown to be sensitive to structural renal tissue changes only at a late stage, often delaying clinical intervention. Conversely, quantitative magnetic resonance imaging (qMRI), including determination of perfusion by arterial spin labeling (ASL), oxygenation by blood-oxygenation-level-dependent (BOLD) MRI, diffusion by diffusion-weighted imaging (DWI), and viscoelasticity by magnetic resonance elastography (MRE), allows noninvasive assessment of the structural-functional properties of kidney transplants in vivo. For this reason, innovative qMRI and MRE parameters of native and transplant kidneys will be collected for the first time and tested for the clinical evaluation of kidney recipients with suspected acute kidney transplant rejection. For this purpose, native kidneys in healthy volunteers and living donors before explantation as well as transplant kidneys after implantation and in recipients with acute transplant rejection will be investigated by ASL, BOLD-MRI, DWI, and MRE. It is expected that the multiparametric analysis of the quantitative MRI data obtained with our protocols will allow conclusions to be drawn about early pathological functional-structural changes in kidney transplants and to thus improve therapeutic decision-making and clinical management of acute rejection episodes after kidney transplantation.