Quantitative MRI and MR Elastography in Renal Transplants

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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.