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

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

doi:10.3389/fmed.2023.1169451

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

Front Med (Lausanne). 2023 Jun 28:10:1169451. doi: 10.3389/fmed.2023.1169451. eCollection 2023.

Authors

Matthias Weissinger^{1

2}, Kyra Celine Seyfried², Stephan Ursprung¹, Salvador Castaneda-Vega^{2

3}, Ferdinand Seith¹, Sebastian von Beschwitz², Jonas Vogel^{1

2}, Patrick Ghibes¹, Konstantin Nikolaou^{1

4

5}, Christian la Fougère^{2

4

5}, Helmut Dittmann²

Affiliations

¹ Department of Diagnostic and Interventional Radiology, University Hospital Tuebingen, Tuebingen, Germany.
² Department of Nuclear Medicine and Clinical Molecular Imaging, University Hospital Tuebingen, Tuebingen, Germany.
³ Department of Preclinical Imaging and Radiopharmacy, Werner Siemens Imaging Center, Eberhard Karls University Tuebingen, Tuebingen, Germany.
⁴ iFIT-Cluster of Excellence, Eberhard Karls University Tuebingen, Tuebingen, Germany.
⁵ German Cancer Consortium (DKTK), Partner Site Tuebingen, Tuebingen, Germany.

Abstract

Objective: 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.

Methods: In total, 25 consecutive patients who underwent SSR-PET/CT (Siemens Biograph mCT^®) 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 [⁶⁸Ga]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 (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 (GFR_{CDK - EPI}).

Results: SUVmean of the parenchymal tracer retention showed a negative correlation with TER_MAG (r: -0.519, p < 0.001) and GFR_{CDK - 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 % 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).

Keywords: DOTATATE; NET (neuro-endocrinal tumors); PRRT (peptide receptor radionuclide therapy); SSR PET/CT; accumulation index; single-sided renal function; split renal function; total kidney accumulation.

Grants and funding

This study was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy (EXC 2180-390900677).