**Author details**

DMSA has been successfully applied in the evaluation of renal function in living donors (before and after transplantation) and in kidney recipients [58]. For dynamic imaging 99mTc-mercap‐ toacetyltriglycine (MAG-3) and diethylenetriaminepentaacetic acid (DTPA) are the most com‐ monly used tracers, whereas MAG-3 is going to replace DTPA because of superior extraction efficiency. It was proposed that MAG-3 scintigraphy can be useful for discrimination of AR from ATN [59]. Despite a reasonable perfusion and tracer extraction in ATN as assessed in these studies, tracer excretion rate is low, whereas one of the typical findings in AR is impaired perfusion. This fact was already taken into account by Hilson *et al.* in the seventies who de‐ veloped a DTPA-based perfusion index which allows separation of rejection from ATN and, particularly, rejection from healthy kidneys [60]. These findings are somehow discrepant to typical findings in ultrasound when assessing RI which reflects renal perfusion as well. High RIs can be observed in ATN as well as in AR denying a differentiation of these entities by ultrasound-based measure of renal perfusion. Potentially, the modified renal perfusion index using 18F-fluoride developed by us can be used for further clarification [61]. Aside from this recent studies using PET for the evaluation of renal function other approaches have been

98 Current Issues and Future Direction in Kidney Transplantation

emerged. Renal blood flow for instance was successfully measured with H2

is not disease specific but can assist in the differential diagnoses of AR.

as of the progression of lesions and therefore on graft´s prognosis.

**6. Conclusion**

**Acknowledgements**

bereich 656, Münster, Germany (SFB 656 C7).

[62,63]. Furthermore, we established 18F-fluoride clearance for assessment of renal function in different renal failure models including AR [43,46]. As said before, decreased renal function

The diagnosis and therapy follow-up of AR in transplant recipients demands for non-invasive and serial imaging approaches *in vivo.* Molecular and cellular imaging has significant potential for transplantation medicine as it may serve for monitoring the graft. With more optimal trac‐ ers as they are numerously being developed, PET (and other devices) may serve as valuable tools for the diagnosis and management of renal AR. In this term, these techniques will find their share to impact on detection of AR, graft function, assessment of therapy response as well

Taken the new developments in molecular imaging into account, non-invasive methods in‐ cluding ultrasound, magnetic resonance, as well as SPECT and PET get increasingly helpful for research. Currently, nearly all of these promising new approaches are still at an experi‐ mental stage and have to evidence their potential in humans in daily routine in the future.

This work was supported by the Deutsche Forschungsgemeinschaft (DFG), Sonderforschungs‐

Alexander Grabner1 , Dominik Kentrup1 , Uta Schnöckel2 , Michael Schäfers3 and Stefan Reuter1\*

\*Address all correspondence to: sreuter@uni-muenster.de

1 Department of Internal Medicine D, Experimental Nephrology, University of Münster, Münster,, Germany

2 Department of Nuclear Medicine, University of Münster, Münster,, Germany

3 European Institute for Molecular Imaging, University of Münster, Münster, Germany
