A Comparison of [sup.68]Ga-PSMA PET/CT-Based Split Renal Function with [sup.99m]Tc-MAG3 Renography in Patients with Metastatic Castration-Resistant Prostate Carcinoma Treated with [sup.177]Lu-PSMA

• Published in: Diagnostics (Basel) 2024-03, Vol.14 (6)
• Main Authors: Gabela, Lerato, Mkhize, Thokozani, Hadebe, Bawinile, Harry, Lerwine, Nxasana, Thembelihle, Ndlovu, Nontobeko, Pillay, Venesen, Masikane, Sphelele, Patel, Maryam, Nyakale, Nozipho Elizabeth, Vorster, Mariza
• Format: Article
• Language: English
• Subjects: Care and treatment; Diagnosis; Disease susceptibility; Metastasis; PET imaging; Prostate cancer
• ISSN: 2075-4418; 2075-4418
• DOI: 10.3390/diagnostics14060578

Background: Physiological PSMA expression in the cells of the proximal renal tubules and consecutive radiopharmaceutical binding and retention could potentially lead to radioligand-therapy-induced nephrotoxicity. Thus, patients with metastatic castration-resistant prostate cancer undergo [sup.99m]Tc-Mercaptoacetyltriglycine (MAG3) renal scintigraphy to assess kidney function and to exclude renal obstruction as part of their workup for PSMA-targeted radioligand therapy (RLT). [sup.99m]Tc-MAG-3 renal scintigraphy often requires an additional visit to the nuclear medicine department and patients spend 30–90 min in the department, which is inconvenient and takes up camera time. In addition, the patients are subjected to a baseline [sup.68]Ga-PSMA PET/CT to assess for PSMA-positive disease prior to targeted radioligand therapy. The aim of this retrospective cross-sectional study was to compare [sup.99m]Tc-MAG-3-based split renal function (SRF) with [sup.68]Ga-PSMA-derived SRF. Methods: This retrospective cross-sectional study included 28 patients with histologically proven metastatic castration-resistant prostate cancer (mCRPC) who received 177Lu-PSMA617. A comparison between the split renal function using [sup.68]Ga-PSMA PET/CT and the [sup.99m]Tc-MAG-3-derived split renal function was carried out in 56 kidneys (n = 56). The SRF on [sup.68]Ga-PSMA was calculated using the volume and the average standard uptake value (SUVmean) within each VOI calculated as previously described by Roser et al.: SRF = (VOLUMEright) ∗ SUVmeanright/(VOLUMEright ∗ SUVmeanright + VOLUMEleft ∗ SUVmeanleft). Paired tests and correlation coefficients were used to compare [sup.68]Ga-PSMA and [sup.99m]Tc-MAG-3. A visual comparison of kidney morphology on both studies was also performed. Results: The median SRF of the right kidney was 49.9% (range: 3–91%) using [sup.68]Ga-PSMA PET/CT and 50.5% (range: 0–94%) with [sup.99m]Tc-MAG3 scintigraphy. Notably, there was a strong correlation between SRF measurements obtained from PSMA and [sup.99m]TcMAG3, with a Pearson correlation coefficient of 0.957 (p < 0.001). Both [sup.99m]Tc-MAG3 and [sup.68]Ga-PSMA PET/CT studies identified morphological renal abnormalities; there were nine hydronephrotic kidneys, four shrunken kidneys and one obstructed kidney, and there was a strong positive correlation between [sup.68]Ga-PSMA kidney morphology and [sup.99m]TcMAG3 renal scintigraphy kidney morphology, with a correlation coefficient of 0.93. Conclusions: P