MTI in Biochemical Recurrent Disease: What Threshold, Which Images?

How to cite: Orio PF. MTI in Biochemical Recurrent Disease: What Threshold, Which Images? Grand Rounds in Urology. February 2026. Accessed Oct 2026. https://grandroundsinurology.com/mti-in-biochemical-recurrent-disease-what-threshold-which-images/

Summary

Peter F. Orio III, DO, MS, FABS, FASTRO, Chair, Department of Radiation Oncology at the Dana-Farber Cancer Institute, and Associate Professor, Harvard Medical School, Boston, Massachusetts, provides a framework for using molecular tumor imaging (MTI) in biochemical recurrent prostate cancer, focusing on when to image, which modality to use, and how imaging should influence treatment decisions. He emphasizes that imaging should be performed only when results will change management and should not delay indicated salvage radiation therapy.

Dr. Orio outlines key definitions of biochemical recurrence. After radical prostatectomy, recurrence is defined as a prostate-specific antigen (PSA) level of 0.2 or higher, confirmed or rising. After radiation therapy, recurrence is defined using the Phoenix criteria. These definitions establish the clinical context before selecting imaging.

He explains that prostate-specific membrane antigen positron emission tomography (PSMA PET) is the preferred modality in most salvage settings, but it has limitations at low PSA levels. Importantly, a negative scan does not exclude microscopic disease and should not be used to defer treatment.

Dr. Orio emphasizes that the primary role of imaging is to guide treatment planning rather than determine whether to treat. In the post-prostatectomy setting, imaging informs radiation field design, including decisions regarding prostate bed treatment, pelvic lymph node coverage, and dose escalation. In the post-radiation setting, magnetic resonance imaging and biopsy are required to confirm local recurrence, with PSMA PET used to exclude metastatic disease.

He reviews evidence from the EMPIRE trials demonstrating that PET-guided radiation planning improves event-free survival and that dose escalation to PET-avid sites further enhances outcomes. He notes that tracer selection generally affects logistics and availability rather than clinical decision making.

Dr. Orio emphasizes that optimal care requires selecting the right imaging modality at the right time, aligned with disease state, treatment intent, and prostate-specific antigen kinetics, while preserving the early salvage treatment window.

The International Prostate Cancer Update (IPCU), is a multi-day, CME-accredited conference focused on new developments in prostate cancer treatment, diagnosis, and prevention. IPCU 36 featured interactive discussions, panel roundtables, debates, and case reports. This conference is led by expert physicians and is designed for urologists, medical oncologists, radiation oncologists, and other healthcare professionals involved in the diagnosis and treatment of prostate cancer.

The goal of this educational program is to equip healthcare professionals involved in the diagnosis and treatment of prostate cancer with the up-to-date clinical knowledge and tools they need to best treat their patients. The program will discuss the treatment of prostate cancer from diagnosis to treating advanced and metastatic disease. The conference aims to give physicians exposure to a comprehensive review of treating prostate cancer patients and to give them a chance to discuss the issues with peers and experts.