How to cite: Collins SP. “What the Urologist Needs to Know about Molecular Targeted Imaging (MTI) and Theranostics.” Grand Rounds in Urology. November 2025. Accessed Jan 2026. https://grandroundsinurology.com/what-the-urologist-needs-to-know-about-molecular-targeted-imaging-mti-and-theranostics
Summary
Sean P. Collins, MD, PhD, Professor of Radiation Oncology, University of South Florida, Tampa, Florida, discusses key developments in prostate-specific membrane antigen (PSMA) imaging and its therapeutic implications for urologists and radiation oncologists. He begins by contrasting magnetic resonance imaging (MRI)-based target volumes with PSMA-based biologic target volumes, noting that PSMA imaging better correlates with tumor extent on whole-mount pathology. He predicts that PSMA-guided planning will replace MRI-guided planning for stereotactic body radiation therapy (SBRT) because PSMA expression more accurately reflects disease biology and aggressiveness.
Dr. Collins reviews available PSMA tracers, including 18F-based agents, and emphasizes that not all tracers are equivalent. 18F agents produce crisper images with less bladder and ureteral uptake, improving localization and reducing misinterpretation. He cautions that excessive uptake in the urinary tract can obscure local recurrence or mimic lymph node disease, underscoring the need for careful image interpretation when planning radiation fields.
He also discusses the limitations of PSMA imaging. While highly specific, it remains insensitive to microscopic disease. Negative scans do not rule out pelvic metastases, and data suggest continued benefit from pelvic radiation in high-risk, PSMA-negative patients.
Dr. Collins then outlines emerging applications of SBRT for hormone-sensitive and castration-resistant prostate cancer, referencing European PEACE and LUNAR trials showing improved progression-free survival when SBRT is combined with systemic therapy. He emphasizes that radionuclide-based therapies, such as lutetium PSMA-617, may eventually supplant PSMA-guided external beam radiation. Still, he stresses that urologists must understand Molecular Targeted Imaging (MTI) interpretation to guide multidisciplinary decision-making today.
ABOUT THE AUTHOR
Sean P. Collins, MD, PhD, is a Professor of Radiation Oncology and the Vice Chair of Faculty Affairs at the University of South Florida Morsani College of Medicine in Tampa, Florida. In July 2006, Dr. Collins joined his twin brother Brian on the faculty of the Cancer Center at Georgetown University Hospital as an Attending Physician in Radiation Oncology. Dr. Collins graduated from the Medical Scientist Training Program (MSTP) at the University of Michigan in 2001. Dr. Collins completed both an internship in Surgery and a residency in Radiation Oncology at Georgetown University Hospital. His area of expertise is prostate cancer, for which he treats patients using the CyberKnife®, a technology that allows for more accurate targeting of radiation therapy. Dr. Collins is a physician-scientist, and his work focuses on developing prostate cancer treatment protocols using stereotactic body radiation therapy (SBRT) to minimize the toxicity of radiation dose escalation. To date, he has treated over 2500 prostate cancer patients with SBRT and has presented his work at major meetings and published multiple papers on his experience in peer-reviewed journals.
