The investigators will perform a study with 25 patients in whom the investigators have a strong suspicion of prostate cancer that has returned to the body after having an initial treatment. The major goal of the investigation is to see whether anti-[18F] FACBC PET-CT and MRI imaging individually will be useful in the detection of local and extraprostatic recurrence of prostate cancer. Routine blood test will be done on the day of the FACBC scan and one week later as required by the FDA. All patients will undergo biopsy of the prostate as clinically appropriate per standard of care. If either the FACBC or MRI scans indicate cancer recurrence, the subject's cancer site(s) will also be biopsied as clinically appropriate.

Prostate cancer is the most common solid tumor, with approximately 200,000 new cases diagnosed per year. Several different local therapies are available for treatment, including surgery and radiotherapy. Significant advances have been made which have improved the cancer control outcomes and treatment. Despite these significant advances, approximately 30% of patients treated with definitive local therapy experience recurrent disease. Recurrent (returning) disease usually displays rising Prostate-Specific Antigen (PSA) (a blood test for prostate cancer). The PSA level is often of limited use in differentiating local recurrence (i.e. recurrence in the prostate bed) from recurrence outside of the prostate bed (extra-prostatic recurrence). Imaging plays a central role in the detection of recurrent prostate carcinoma in the prostate bed and in the differentiation of prostatic from extraprostatic recurrence. There are newer methods of imaging such as magnetic resonance imaging (MRI) and positron emission tomography (PET) with molecular radiotracers that are currently under study for the imaging of post-therapy recurrence.

One PET radiotracer which has shown promise in the staging and restaging of patients with prostate carcinoma is anti-1-amino-3-[18F]fluorocyclobutane-1-carboxylic acid (anti-3-[18F]FACBC) which is a synthetic amino acid analog. FACBC demonstrated higher accuracy compared with other methods in the restaging of patients with suspected recurrent prostate carcinoma. FACBC has been tested in over 140 subjects in other studies in the Emory system including 128 subjects with prostate cancer.

The investigators will perform a study with 25 patients in whom the investigators have a strong suspicion of prostate cancer that has returned to the body after having an initial treatment. The major goal of the investigation is to see whether anti-[18F] FACBC PET-CT and MRI imaging individually will be useful in the detection of local and extraprostatic recurrence of prostate cancer. Routine blood test will be done on the day of the FACBC scan and one week later as required by the FDA.

All patients will undergo biopsy of the prostate as clinically appropriate per standard of care. If either the FACBC or MRI scans indicate cancer recurrence, the subject's cancer site(s) will also be biopsied as clinically appropriate. Biopsy of the suspected recurrence sites will be scheduled at the subjects' convenience as soon as possible after the scans.

Tissue obtained from the biopsy will undergo standard analysis to determine if prostate carcinoma cells are present. The secondary aim is to use left-over biopsy material to determine if there are genotypic differences between prostate carcinoma recurrence confined to the prostate bed and extraprostatic recurrence

Inclusion Criteria:

1. Patients must be 18 years of age or older.
2. Patients will have been originally diagnosed with localized (Stage T1c, T2, or T3 ) prostate carcinoma and have undergone what was considered definitive non-prostatectomy therapy for localized disease.
3. In the case of cryotherapy, external beam radiation, or High-Intensity Focused Ultrasound (HiFU) the procedure will have occurred at least one year in the past. In the case of brachytherapy, treatment will have occurred at least 2 years in the past to eliminate patients with so-called "PSA bump."
4. Patient will have suspicion of recurrent prostate carcinoma as defined by: the Radiation Therapy Oncology Group (RTOG) - American Society for Therapeutic Radiology and Oncology (ASTRO) Phoenix criteria of nadir PSA +2, and absolute PSA ≥ 4.0 ng/ml.with any doubling time (DT) or with PSA 2.0-3.99 ng/ml with DT ≤10 months
5. Ability to lie still for PET scanning
6. Patients must be able to provide written informed consent.

Exclusion Criteria:

1. Age less than 18.

2. Greater than T3 disease in past and/or treated with prostatectomy.

3. Less than 1 year since cryotherapy,external beam radiation therapy, or HiFU or 2 years since brachytherapy..

4. Does not meet above criteria of suspicious PSA elevation

5. Inability to lie still for PET scanning

6. Cannot provide written informed consent.

7. Bone scan findings characteristic for metastatic prostate carcinoma

8. Less than 1 month since any prior prostate biopsy (to decrease false positive uptake from inflammation).

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Participants completing both scans are included in the baseline analysis.

Adverse events related to the study procedures were collected from the time a participant consented to take part in the trial through all study related procedures (up to 29 days, which is the maximum number of days between a participant receiving both imaging tests). Adverse events related to the study procedures were not expected.