Renal PET imaging with Rubidium-82 in humans

Objectives Ru-82 chloride is a tracer with high first pass extraction and slow washout in the kidneys. The goal of this preliminary study was to investigate the feasibility of human kidney imaging with Rb-82 PET and obtain first quantitative data on its uptake noninvasively.

Methods Eight healthy volunteers underwent dynamic PET/CT imaging as part of Human Biodistribution and Radiation Dosimetry of 82Rb (Senthamizhchelvan et al., JNM 2010, 51:1592-9). Time Activity Curves (TACs) were generated from the left ventricle, descending thoracic aorta, abdominal aorta, and kidneys. Two-compartment modeling was applied and the K1 parameter was used for estimation of renal blood flow. As a first approximation of partial volume correction, TACs from thoracic and abdominal aorta were rescaled to match maximum activity of left ventricle.

Results Table 1 shows the mean and standard deviations of K1. Correlation between K1 values obtained with LVdiff and AAsame was excellent (r=0.86).

Conclusions There is good reproducibility of compartmental model parameters. R-82 PET images have high resolution with good renal cortex delineation. Potential applications include diseases with limited applicability of MRI or CTA due to increased creatinine such renovascular disease, ATN, and acute and chronic transplant nephropathy.

Research Support The human Rubidium-82 dosimetry study was supported by a research grant from Bracco Diagnostics Inc. Additional support came from the NIDDKD grant RO1DK050183

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Table 1: Mean and standard deviation of renal K1 calculated using various input functions.

LV: left ventricle; TA: desc. thoracic aorta; AA: abdominal aorta; same: same bed position and injection as kidneys; diff: different bed position and injection from kidneys