Background Prostate cancer (PCa) is the most common cancer in men worldwide. Targeting prostate-specific membrane antigen (PSMA) using radiopharmaceuticals has shown promising results for PCa imaging as well as theranostics.… Click to show full abstract
Background Prostate cancer (PCa) is the most common cancer in men worldwide. Targeting prostate-specific membrane antigen (PSMA) using radiopharmaceuticals has shown promising results for PCa imaging as well as theranostics. 68Ga-based PSMA imaging is limited by production of small quantities by generator, and it has led to quest for cyclotron produced 18F-based PSMA ligands. In the current study, we evaluated the biodistribution and internal dosimetry of 18F-PSMA-1007 and compared it with 68Ga-PSMA-11-HBED-CC. Materials and Methods A total of 8 patients with histopathologically proven PCa were included in the study, of whom 4 patients underwent 18F-PSMA-1007, and the other 4 patients underwent 68Ga-PSMA-11-HBED-CC PET/CT. The biodistribution of both tracers was quantified for different organs by computing SUVs. All the patients underwent 5-point serial imaging to compute equivalent dose to essential organs and whole-body effective dose using OLINDA-based dosimetry. Results The radiotracer uptake in brain, lacrimal gland, salivary gland, heart, lung, liver, gallbladder, spleen, pancreas, intestine, gluteal muscle, and bone marrow were found to be higher in 18F-PSMA-1007 PET as compared with 68Ga PSMA-11 PET. Kidney and urinary bladder showed higher SUV value on 68Ga-PSMA-11-HBED-CC as compared with 18F-PSMA-1007. The whole-body effective dose from 18F-PSMA-1007 (1.46E−02 mSv/MBq) was higher than 68Ga-PSMA-11-HBED-CC (1.03E−02 mSv/MBq). The highest mean equivalent dose from 18F-PSMA-1007 was observed in the kidneys (1.48E−01 mGy/MBq), followed by spleen (mean, 1.06E−01 mGy/MBq) and liver (6.80E−02 mGy/MBq), whereas 68Ga-PSMA-11-HBED-CC equivalent dose was maximum in the kidneys (2.13E−01 mGy/MBq), followed by liver (3.03E−02 mGy/MBq), spleen (2.90E−02 mGy/MBq), adrenals (2.67E−02 mGy/MBq), and urinary bladder (1.89E−02 mGy/MBq). Conclusion Whole-body effective dose from 18F-PSMA-1007 is higher compared with 68Ga-PSMA-11-HBED-CC. 18F-PSMA-1007 shows lesser urinary bladder clearance compared with 68Ga-PSMA-11-HBED-CC, which can allow better interpretation of prostatic bed without significant radioactive urine interference. 18F-PSMA-1007 is a cyclotron-produced alternative to generator-produced 68Ga-PSMA-11-HBED-CC and can emerge as a good diagnostic surrogate for patients planned for 177Lu-PSMA-617 therapy.