Prospective Comparison of PET Imaging with PSMA-Targeted ¹⁸F-DCFPyL Versus Na¹⁸F for Bone Lesion Detection in Patients with Metastatic Prostate Cancer

Abstract

Bone metastases in prostate cancer (PCa) have important prognostic significance, and imaging modalities used for PCa staging should have high sensitivity for detecting such lesions. Prostatespecific membrane antigen (PSMA)-targeted PET radiotracers are promising new agents for imaging PCa. We undertook a head-tohead comparison of PSMA-targeted 2-(3-{1-carboxy-5-[(6-18 Ffluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid (18 F-DCFPyL) PET to Na 18 F PET to determine which modality was more sensitive for the detection of lesions suggestive of bone metastases in a group of patients with metastatic PCa. Methods: Patients with progressive, metastatic PCa were prospectively imaged with both 18 F-DCFPyL and Na 18 F PET/CT, with both scans occurring within 24 h of each other. A consensus 2-reader central review was performed to identify all bone lesions suggestive of sites of PCa involvement on both scans, and maximized SUVs corrected for body weight (SUV max) and lean body mass (SUL max) were recorded. Soft-tissue lesions were also noted on both scans, and SUV max , SUL max , and PSMA reporting and data system (RADS) version 1.0 scores were recorded. Data from the 2 scans were compared using a generalized estimating equation. Results: In total, 16 patients meeting all inclusion criteria were enrolled in this study, and 15 of the 16 (93.8%) were imaged with both PET radiotracers. In total, 405 bone lesions suggestive of sites of PCa were identified on at least 1 scan. On 18 F-DCFPyL PET/CT, 391 (96.5%) were definitively positive, 4 (1.0%) were equivocally positive, and 10 (2.5%) were negative. On Na 18 F PET/CT, the corresponding values were 388 (95.8%), 4 (1.0%), and 13 (3.2%). Of the definitively negative lesions on 18 F-DCFPyL PET, 8 of 10 (80.0%) were sclerotic and 2 of 10 (20.0%) were infiltrative or marrow-based. Additionally, 12 of 13 (92.3%) of the definitively negative lesions on Na 18 F PET were infiltrative or marrow-based and 1 of 13 (7.7%) was lytic. Also identified were 78 PSMA-RADS-4, 17 PSMA-RADS-5, and 1 PSMA-RADS-3C soft-tissue lesions. Conclusion: PET/CT imaging using 18 F-DCFPyL and Na 18 F PET had nearly identical sensitivities for the detection of bone lesions in patients with metastatic PCa. As would be expected, PSMA-targeted PET provides more information on soft-tissue disease. There may be little additional value to imaging PCa patients with Na 18 F after a PSMA-targeted PET scan has already been performed.

Quantitative Evaluation of PSMA PET Imaging using a Realistic Anthropomorphic Phantom and Shell-less Radioactive Epoxy Lesions

“…Harmonization of clinical trials can enable development of robust multi-centre studies and lead to improved predictive modelling for prostate cancer (29)(30)(31)(32). Given the increasing number of clinical trials using PSMA PET (3,4,(33)(34)(35)(36), there is significant motivation to validate quantitative metrics for different lesion sizes and reconstruction parameters. In this study, we aimed to evaluate PSMA PET quantitation by performing a phantom study using radioactive epoxy spheres to simulate lesions with known ground truth.…”

Piflufolastat F 18: Diagnostic First Approval

“…However, piflufolastat F 18 PET/CT imaging was more effective than Na 18 F PET in detecting soft tissue metastases (positive findings in 73.3% vs 40% of patients). All suggestive soft tissue findings with Na 18 F PET had uptake with piflufolastat F 18, but with evidence of more widespread soft tissue involvement [20].…”

Molecular Imaging of Bone Metastases and Their Response to Therapy

“…Several studies have reported higher sensitivity than bone scintigraphy (57)(58)(59) and similar or better sensitivity than 18 F-Fluoride PET/CT (57,60). These results suggest that if PSMA PET/CT imaging is performed, then additional bone-specific imaging is not required in the majority of patients (58)(59)(60). However, one study showed a lower sensitivity for detecting bone metastases in patients with advanced disease scheduled for radionuclide therapy (61).…”