[18F]-PSMA-1007-PET for evaluation of kidney function

Prostate-specific membrane antigen (PSMA) is present in the proximal tubule cells of the kidneys. This results in high renal tracer uptake in PSMA-PET, which may contain useful information on renal function. As part of the evaluation for [¹⁷⁷Lu]-PSMA therapies, patients undergo PSMA-PET and additional [^99mTc]-mercapto-acetyltriglycine (MAG3) scintigraphy to assess renal function. Aim of this study was to evaluate estimation of renal function with [¹⁸F]-PSMA-1007-PET/CT (PSMA-PET) by comparison to timely MAG3-scintigraphies.

We retrospectively investigated 73 prostate cancer patients with 93 timely available PSMA-PET/CT, MAG3-scintigraphies and serum creatinine. For determination of split renal function in PSMA-PET/CT, we evaluated the relative unilateral total renal PSMA uptake, i.e. SUV_mean multiplied by the renal volume (SRF_PSMA-TOTAL) and relative unilateral maximal standardized uptake value (SRF_SUV). These were compared to MAG3 split renal function (SRF_MAG3) using Pearson correlation and receiver operating characteristics analysis. For determination of global renal function, correlation of bilateral total renal PSMA uptake with MAG3 tubular excretion rate and serum creatinine was assessed.

SRF_MAG3 was strongly correlated with SRF_PSMA-TOTAL (r= 0.872, p<0.001) and with SRF_SUV (r=0.815, p<0.001). Relevant abnormalities of SRF_MAG3 (unilateral renal function < 25 %) could be detected with sensitivities and specificities of 90% and 92% for SRF_PSMA-TOTAL, and 80% and 95% for SRF_SUV. Measures of absolute renal function were only weakly correlated with bilateral total renal PSMA uptake.

Renal [¹⁸F]-PSMA-1007 uptake allowed to quantify renal split function with good accuracy based on SRF_PSMA-TOTAL or SRF_SUV.