AUTHOR=Weissinger Matthias , Seyfried Kyra Celine , Ursprung Stephan , Castaneda-Vega Salvador , Seith Ferdinand , von Beschwitz Sebastian , Vogel Jonas , Ghibes Patrick , Nikolaou Konstantin , la Fougère Christian , Dittmann Helmut 

TITLE=Non-invasive estimation of split renal function from routine 68Ga-SSR-PET/CT scans

JOURNAL=Frontiers in Medicine

VOLUME=Volume 10 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2023.1169451

DOI=10.3389/fmed.2023.1169451

ISSN=2296-858X

ABSTRACT=Objective: Patients with impaired kidney function are at elevated risk for nephrotoxicity and hematotoxicity from peptide radio receptor therapy (PPRT) for advanced neuroendocrine tumors. Somatostatin receptor (SSR)-PET/CT imaging is the method of choice to identify sufficient SSR expression as a prerequisite for PRRT. Therefore, the aim of our study was to explore, whether split renal function could be evaluated using imaging data from routine SSR-PET/CT prior to PRRT.

Methods: 25 consecutive patients who underwent SSR-PET/CT (Siemens Biograph mCT®) before PRRT between June 2019 and December 2020 were enrolled into this retrospective study. PET acquisition in caudocranial direction started 20 ±0.5min after i.v. injection of 173 ±20MBq [68Ga]Ga-ha DOTATATE and the kidneys were scanned at 32 ±0.5min p.i.. The renal parenchyma was segmented semi-automatically using an SUV-based isocontour (SUV between 5-15). Multiple parameters including SUVmean of renal parenchyma and blood pool as well as parenchyma volume were extracted and Accumulation Index (ACI: renal parenchyma volume / SUVmean) and Total Kidney Accumulation (TKA: SUVmean x renal parenchyma volume) were calculated. All data were correlated with the reference standard tubular extraction rate (TER-MAG) from [99mTc]Tc-MAG3 scintigraphy and glomerular filtration rate (GFRCDK-EPI).

Results: SUVmean of the parenchymal tracer retention showed a negative correlation with TERMAG (r: -0.519, p<0.001) and GFRCDK-EPI (r:-0.555, p<0.001) at 32 min p.i.. The herein introduced ACI revealed a significant correlation (p<0.05) with the total tubular function (r: 0.482), glomerular renal function (r: 0.461), split-renal function (r: 0.916) and absolute single-sided renal function (r: 0.549). The mean difference between the split renal function determined by renal scintigraphy and ACI was 1.8% ±4.2 percent points.

Conclusion: This pilot study indicates that static [68Ga]Ga-ha DOTATATE PET-scans at 32 min p.i. may be used to estimate both split renal function and absolute renal function using the herein proposed “Accumulation Index” (ACI).