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=10

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=<sec><title>Objective</title><p>Patients with impaired kidney function are at elevated risk for nephrotoxicity and hematotoxicity from peptide receptor radionuclide 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, our study aimed to explore whether split renal function could be evaluated using imaging data from routine SSR-PET/CT prior to PRRT.</p></sec><sec><title>Methods</title><p>In total, 25 consecutive patients who underwent SSR-PET/CT (Siemens Biograph mCT<sup>®</sup>) before PRRT between June 2019 and December 2020 were enrolled in this retrospective study. PET acquisition in the caudocranial direction started at 20 ± 0.5 min after an i.v. injection of 173 ± 20 MBq [<sup>68</sup>Ga]Ga-ha DOTATATE, and the kidneys were scanned at 32 ± 0.5 min p.i. The renal parenchyma was segmented semi-automatically using an SUV-based isocontour (SUV between 5 and 15). Multiple parameters including SUVmean of renal parenchyma and blood pool, as well as parenchyma volume, were extracted, and accumulation index (<bold>ACI</bold>: renal parenchyma volume/SUVmean) and total kidney accumulation (<bold>TKA</bold>: SUVmean x renal parenchyma volume) were calculated. All data were correlated with the reference standard tubular extraction rate (TER-MAG) from [<sup>99m</sup>Tc]Tc-MAG3 scintigraphy and glomerular filtration rate (GFR<sub>CDK − EPI</sub>).</p></sec><sec><title>Results</title><p>SUVmean of the parenchymal tracer retention showed a negative correlation with TER<sub>MAG</sub> (<italic>r</italic>: −0.519, <italic>p</italic> &lt; 0.001) and GFR<sub>CDK − EPI</sub> (<italic>r</italic>: −0.555, <italic>p</italic> &lt; 0.001) at 32 min p.i. The herein-introduced ACI revealed a significant correlation (<italic>p</italic> &lt; 0.05) with the total tubular function (<italic>r</italic>: 0.482), glomerular renal function (<italic>r</italic>: 0.461), split renal function (<italic>r</italic>: 0.916), and absolute single-sided renal function (<italic>r</italic>: 0.549). The mean difference between the split renal function determined by renal scintigraphy and ACI was 1.8 ± 4.2 % points.</p></sec><sec><title>Conclusion</title><p>This pilot study indicates that static [<sup>68</sup>Ga]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).</p></sec>