Abstract
OBJECTIVES: We record quantitative differences between (18)F-prostate specific membrane antigen ((18)F-PSMA)-1007 and [(68)Ga]Ga-PSMA-11 positron emission tomography (PET) prostate scans at our centre to investigate if significant differences exist between suspected lesion and lesion/ background parameters studied. We also assess the potential impact of such differences on tracer interchangeability when supply is constrained. METHODS: Sixty-one [(68)Ga]Ga-PSMA-11 and seventy-two (18)F-PSMA-1007 patients were analysed in two cohorts, each comprising 200 lesions. Clinical reports were used to determine maximum standard uptake values (SUV(max)) was recorded for suspected lesions (T). Similarly, normalisations of mean standardized uptake (SUV(mean)) and standardized uptake value-peak (SUV(peak)) using lean body mass (SUV(Ibm)) and body surface area (SUV(bsa)) were estimated. SUV(mean) of liver backgrounds (B) was recorded to estimate T/B ratios. Metabolic tumour volume and total lesion PSMA (TL-PSMA) were investigated as functional volume surrogates. The Mann-Whitney U test was used to identify significant differences between the [(68)Ga]Ga-PSMA-11 and (18)F-PSMA-1007 distributions. RESULTS: Significant differences were observed for lesion SUV(max) (p=0.0004), SUV(peak) (p=0.0017), SUV(mean) (p=0.0007), SUV(Ibm) (p=0.0002), and SUV(bsa) (p=0.0005) in lesions with higher [(68)Ga]Ga-PSMA-11 SUV. Similarly, significant differences were observed in liver SUV(max) (p<0.0001), SUV(peak) (p<0.0001), and SUV(mean) (p<0.0001), with higher values for (18)F-PSMA-1007. T/B (p<0.0001) and TL-PSMA (p=0.0063) also exhibited significantly higher [(68)Ga]Ga-PSMA-11 values. CONCLUSION: Consistent, predictable, and significant differences were observed in (18)F-PSMA-1007 and [(68)Ga]Ga-PSMA-11 PET scans of lesion, liver, volume surrogates, supporting tracer interchangeability for patients with suspected prostate cancer. Our results also support the recent commissioning of PSMA-based PET tracers in England.