An exploratory, feasibility and proof-of-concept study to evaluate the capability of a rectal probe scintigraphy device (ProxiScanTM) to detect PSMA specific radiopharmaceutical agent (ProstaScint®; as a surrogate marker for prostate cancer) in patients who have undergone a radical prostatectomy for their disease, patients with multiple negative prostate biopsies and patients with known primary prostate cancer. Developed by Hybridyne Imaging Technologies, Inc. ProxiScanTM is a small cadmium zinc telluride (CST)-based compact gamma camera. It is the same size as a trans-rectal ultrasound (TRUS), currently used for prostate biopsy guidance. Men with multiple positive biopsies will be considered controls. Prostate cancer sextant biopsy histology results will be correlated with ProxiScanTM, TRUS, MRI and SPECT/CT. The investigators hypothesize that it will be safe and feasible to utilize a rectal probe scintigraphy (ProxiScanTM) to detect PSMA specific ProstaScint®, thus identifying and localizing the tumour sites within the prostate and surrounding areas.

Inclusion Criteria:

Group 1: Rising PSA (biochemical failure) following radical prostatectomy. Group 2: Rising PSA (>10ng/ml) and/or abnormal digital rectal exam suspicious for prostate cancer. Previously negative prostate biopsies.

Group 3: Scheduled biopsy for known PCa (patient on AS). At least 1 previously positive prostate biopsy for adenocarcinoma of the prostate.

Patients must meet all of the following inclusion criteria to be eligible for enrollment into the study:

• Sufficient time period to complete the imaging protocol and 7 to 9 day safety follow-up assessment without therapeutic intervention.
• Patient is judged by the Investigator to have the initiative and means to provide written consent and be compliant with the protocol and be able and commits to make the required study visits.
• Ambulatory with ECOG performance status of 0 or 1 (see appendix section).
• Patient is between 35 and 75 years of age.

Exclusion Criteria:

The presence of any of the following will exclude a patient from study enrollment:

• Patient or physician plans definitive concomitant chemotherapy, therapeutic radiation treatment, biologic treatment and/or local ablative treatment for cancer within the interval of study participation.
• Patients with pacemakers, neurostimulators, and foreign metal bodies will be excluded as they will be unable to undergo an MRI and SPECT-CT.
• Prior history of murine antibody infusion, patients who are hypersensitive to products of murine origin or indium-111 chloride.
• Prior therapeutic pelvic irradiation.
• Recent prostate biopsy, within 1 month of study enrollment.
• Patient with contraindications to TRUS-guided prostate biopsy (continuous need for anti-coagulation, no rectum, etc.)
• Clinical evidence of prostatitis, or other benign prostate gland abnormality, that would explain elevated PSA and/or (digital rectal exam) DRE findings.
• Active malignancy or therapy for malignancy within 6 months, other than basal or squamous cell carcinoma of the skin.
• Patient received a radiopharmaceutical which was within 5 physical half-lives at the time of study imaging.
• Severe psychiatric or medical illness that may interfere with compliance with the study protocol or follow-up as deemed by the investigator.