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A Pilot Study of 68Ga-PSMA11 and 68Ga-RM2 PET/MRI for Biopsy Guidance in Patients with Suspected Prostate Cancer.

A Pilot Study of 68Ga-PSMA11 and 68Ga-RM2 PET/MRI for Biopsy Guidance in Patients with Suspected Prostate Cancer. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Duan, H., Ghanouni, P., Daniel, B., Rosenberg, J., Thong, A., Kunder, C., Mari Aparici, C., Davidzon, G. A., Moradi, F., Sonn, G. A., Iagaru, A. 2022

Abstract

Purpose: Targeting of lesions seen on multiparametric MRI (mpMRI) improves prostate cancer (PC) detection at biopsy. However, 20-65% of highly suspicious lesions on mpMRI (PI-RADS 4 or 5) are false positives (FP), while 5-10% of clinically significant PC (csPC) are missed. Prostate specific membrane antigen (PSMA) and gastrin-releasing peptide receptors (GRPR) are both overexpressed in PC. We therefore aimed to evaluate the potential of 68Ga-PSMA11 and 68Ga-RM2 PET/MRI for biopsy guidance in patients with suspected PC. Methods: A highly selective cohort of 13 men, aged 58.0±7.1 years, with suspected PC (persistently high prostate-specific antigen [PSA] and PSA density) but negative or equivocal mpMRI and/or negative biopsy were prospectively enrolled to undergo 68Ga-PSMA11 and 68Ga-RM2 PET/MRI. PET/MRI included whole-body and dedicated pelvic imaging after a delay of 20 minutes. All patients had targeted biopsy of any lesions seen on PET followed by standard 12-core biopsy. Maximum standardized uptake values (SUVmax) of suspected PC lesions were collected and compared to gold standard biopsy. Results: PSA and PSA density at enrollment were 9.8±6.0 (1.5-25.5) ng/mL and 0.20±0.18 (0.06-0.68) ng/mL2, respectively. Standardized systematic biopsy revealed a total of 14 PC in 8 participants: 7 were csPC and 7 were non-clinically significant PC (ncsPC). 68Ga-PSMA11 identified 25 lesions, of which 11 (44%) were true positive (TP) (5 csPC). 68Ga-RM2 showed 27 lesions, of which 14 (52%) were TP, identifying all 7 csPC and also 7 ncsPC. There were 17 concordant lesions in 11 patients vs. 14 discordant lesions in 7 patients between 68Ga-PSMA11 and 68Ga-RM2 PET. Incongruent lesions had the highest rate of FP (12 FP vs. 2 TP). SUVmax was significantly higher for TP than FP lesions in delayed pelvic imaging for 68Ga-PSMA11 (6.49±4.14 vs. 4.05±1.55, P = 0.023) but not for whole-body images, nor for 68Ga-RM2. Conclusion: Our results show that 68Ga-PSMA11 and 68Ga-RM2 PET/MRI are feasible for biopsy guidance in suspected PC. Both radiopharmaceuticals detected additional clinically significant cancers not seen on mpMRI in this selective cohort. 68Ga-RM2 PET/MRI identified all csPC confirmed at biopsy.

View details for DOI 10.2967/jnumed.122.264448

View details for PubMedID 36396456