Non-invasive Evaluation of Graft Condition in Adult Patients With Kidney Transplant Using Ultrasound Localization Microscopy and Multispectral Optoacoustic Tomography

In this study, the condition of the kidney transplant in adults is to be assessed non-invasively using multispectral multispectral optoacoustic tomography and ultrasound localization microscopy. Associated with common diseases such as arterial hypertension, diabetes mellitus and cardiovascular diseases, chronic renal failure is now a leading cause of death worldwide.

Around 10% of adults in Germany, but children are also affected. The terminal stage of renal insufficiency is defined by a glomerular filtration rate (GFR) which is only 15% of the normal rate and the need for renal replacement therapy in the form of dialysis or transplantation.

Not only the higher quality of life, but also the mortality rate make kidney transplantation the procedure of choice whenever possible.

After successful kidney transplantation, regular monitoring and evaluation of the organ transplant is of great importance to detect a rejection reaction as early as possible.

Among other things, this is done during an extensive annual examination. Not infrequently, and especially in the case of abnormalities in the laboratory diagnosis of blood and urine, a kidney biopsy is also necessary in order to assess the condition of the transplant in the best possible way.

As an invasive diagnostic procedure, the biopsy necessitates a stay in hospital, may result in side effects such as postoperative bleeding and represents a risk and an additional bruden for the patient.

MSOT has already been used to measure renal clearance and the biodistribution of fluorescent substances within the kidney, but new biomarkers have also been established in muscle and intestinal diseases and correlated with clinical scores. ULM has made the visualization of glomeruli, the smallest functional unit of the kidney, in living rats and humans and visualization of cerebral microvasculature in the human brain possible. In this study, the renal function in transplant patients will be evaluated as part of the annual examination and results from histology (biopsy), laboratory and ultrasound diagnostics will be correlated with data from MSOT and 2D and 3D ULM imaging.

The investigators believe that MSOT can be used to gain important molecular insights into the condition of the transplant. With ULM the investigators want to analyze the microvascular architecture within glomerular renal corpuscles and identify changes in perfusion dynamics as morphological signs for transplant evaluation.

Inclusion criteria

• kidney transplant
• indication for biopsy set in clinical routine
• minimum 18 years of age
• written consent

Exclusion criteria

• allergy against contrast agents/ SonoVue
• tatoos in examined areas
• contraindication against SonoVue
• pregnant women
• breast feeding women