ACR Appropriateness Criteria® Post-Treatment Follow-up of Prostate Cancer: 2022 Update

Prostate cancer has a wide spectrum ranging between low-grade localized disease and castrate-resistant metastatic disease. Although whole gland and systematic therapies result in cure in the majority of patients, recurrent and metastatic prostate cancer can still occur. Imaging approaches including anatomic, functional, and molecular modalities are continuously expanding. Currently, recurrent and metastatic prostate cancer is grouped in three major categories: 1) Clinical concern for residual or recurrent disease after radical prostatectomy, 2) Clinical concern for residual or recurrent disease after nonsurgical local and pelvic treatments, and 3) Metastatic prostate cancer treated by systemic therapy (androgen deprivation therapy, chemotherapy, immunotherapy). This document is a review of the current literature regarding imaging in these settings and the resulting recommendations for imaging. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Management Impact of Metachronous Oligometastatic Disease Identified on 18F-Fluciclovine (Axumin™) PET/CT in Biochemically Recurrent Prostate Cancer

PURPOSE

We assessed the incidence rate and management impact of oligometastatic disease detected on ¹⁸F-fluciclovine (Axumin™) PET/CT in men with first biochemical recurrence (BCR) of prostate cancer (PCA) after definitive primary therapy.

METHODS AND MATERIALS

We retrospectively reviewed our clinical database for men with PCA who underwent ¹⁸F-fluciclovine PET/CT for imaging evaluation of BCR with negative or equivocal findings on conventional imaging. We included patients with up to and including 5 metastases (oligometastases) regardless of imaging evidence for local recurrence in the treated prostate bed. We examined the association between mean serum prostate specific antigen (PSA) levels with the number of oligometastases (non-parametric ANOVA) and between patients with or without local recurrence (Student t-test). The management impact of oligometastatic disease was tabulated.

RESULTS

We identified 21 patients with oligometastases upon first BCR (PSA 0.2-56.8 ng/mL) out of 89 eligible patients. There was a significant difference (p = 0.04) in the mean PSA levels between patients with local recurrence (n = 12) and those without local recurrence (n = 9). In the subgroup of analysis of patients without local recurrence, there was no significant association between mean PSA level and number of oligometastases (p = 0.83). Distribution of oligometastases included 66.7% isolated nodal disease and 33.3% bone only. Twelve (57.1%) patients had change in management to include change in ADT, salvage therapy, or both. Treatment change was initiated in 62.5%, 28.6%, 66.7%, 100%, and 100% of patients with 1, 2, 3, 4, and 5 oligometastatic lesions, respectively.

CONCLUSION

The incidence rate of oligometastatic disease in men with first BCR of PCA undergoing ¹⁸F-fluciclovine PET/CT for imaging evaluation of BCR was 23.6% in our eligible patient population. There was no significant association between serum PSA level and the number of oligometastases. Treatment management was affected in 57.1% of patients with oligometastases.

Impact of 18F-fluciclovine PET/CT on salvage radiotherapy plans for men with recurrence of prostate cancer postradical prostatectomy

OBJECTIVES

Imaging options to localize biochemical recurrence (BCR) of prostate cancer after radical prostatectomy (RP) are limited, especially at low prostate-specific antigen (PSA) levels. The FALCON study evaluated the impact of 18F-fluciclovine PET/CT on management plans for patients with BCR. Here, we evaluate salvage radiotherapy decisions in patients post-RP.

METHODS

We conducted a subgroup analysis of post-RP patients enrolled in FALCON who had a prescan plan for salvage radiotherapy (± androgen-deprivation therapy). Patients' treatment plans post-18F-fluciclovine PET/CT were compared with their prescan plans. Fisher exact test was used to determine the impact of PSA and Gleason sum on positivity and anatomical patterns of uptake.

RESULTS

Sixty-five (63%) FALCON patients had undergone RP. Of these, 62 (median PSA, 0.32 ng/mL) had a prescan plan for salvage radiotherapy. Twenty-one (34%) had 18F-fluciclovine-avid lesions. Disease was confined to the prostate bed in 11 patients (52%) and to the pelvis in a further 5 (24%), while 5 (24%) had extrapelvic findings. Trends towards more disseminated disease with increasing PSA or Gleason sum were observed but did not reach statistical significance. Postscan, 25 (40%) patients had a management change; 17 (68%) were changed to the treatment modality (8 to systemic therapy, 8 to active surveillance, 1 other) and 8 (32%) were radiotherapy field modifications.

CONCLUSIONS

Incorporating 18F-fluciclovine PET/CT into treatment planning may help identify patients suitable for salvage radiotherapy, help augment planned radiotherapy to better target lesions and support the clinician to optimise patient management.

Incidental Serous Cystadenoma Presenting as a Photopenic Pancreatic Defect on 18F-Fluciclovine PET/CT

ABSTRACT

18F-fluciclovine (Axumin) PET/CT has been widely used for the evaluation of biochemically recurrent prostate cancer following prior treatment. While lymph node and visceral organ metastases typically show increased radiotracer uptake, altered patterns of normal physiologic activity may also provide insight into other disease processes. We present a case of an incidental pancreatic head mass presenting as a photopenic defect on a staging 18F-fluciclovine PET/CT, which was subsequently confirmed to be a benign serous cystadenoma using multisequence MRI.

Validating Modern NRG Oncology Pelvic Nodal and Groupe Francophone de Radiothérapie Urologique Prostate Bed Contouring Guidelines for Post-Prostatectomy Salvage Radiation: A Secondary Analysis of the LOCATE Trial

PURPOSE

We used the patterns of recurrence on ¹⁸F-fluciclovine positron emission tomography (PET)-computed tomography (CT) in patients enrolled in the LOCATE trial after prostatectomy to evaluate how well the most recent NRG Oncology and Groupe Francophone de Radiothérapie Urologique (GFRU) contouring recommendations encompassed all sites of recurrence in the prostate fossa and pelvic nodes in comparison to former Radiation Therapy Oncology Group (RTOG) recommendations.

METHODS AND MATERIALS

Patients with biochemically recurrent prostate cancer after radical prostatectomy with a positive finding within the prostate fossa or pelvic nodes on ¹⁸F-fluciclovine PET/CTs were identified from the LOCATE patient population. Areas of gross disease were delineated. Prostate fossa contours were delineated using both the 2010 RTOG consensus guidelines and the recently published 2020 GFRU consensus guidelines. Pelvic nodes were contoured with both the 2009 RTOG consensus guidelines and the 2020 NRG consensus guidelines. The performance of the contouring guidelines was assessed by determining what proportion of gross recurrent lesions were encompassed completely or marginally.

RESULTS

Of the 213 patients within the LOCATE trial, 45 patients were eligible for analysis with positive ¹⁸F-fluciclovine PET findings. Of the 30 total prostate fossa recurrences, the 2010 RTOG contour covered 20 (67%) and missed or marginally covered 10 (33%). The 2020 GFRU contour covered 27 recurrences (90%), and missed or marginally covered 3 (10%). Of the 43 total nodal recurrences, the 2009 RTOG pelvic nodal contour covered 29 nodes (67%), and missed or marginally covered 14 (32%). The 2020 NRG pelvic nodal contour covered 43 nodes (100%), with no misses or marginal coverage.

CONCLUSIONS

This secondary analysis of the LOCATE trial exemplifies the improved coverage of the latest prostate fossa contouring recommendations from the GFRU. Similarly, it also validates the updated 2020 NRG pelvic nodal contouring guidelines by demonstrating improved coverage of recurrent disease in this patient population.

18F-Fluciclovine PET/CT performance in biochemical recurrence of prostate cancer: a systematic review

BACKGROUND

A systematic literature review of the performance of 18Fluorine-fluciclovine PET/CT for imaging of men with recurrent prostate cancer was performed.

METHODS

Scientific literature databases (MEDLINE, ScienceDirect and Cochrane Libraries) were searched systematically during Oct 2020 using PRISMA criteria. No limit was put on the date of publication. Prospective studies reporting a patient-level 18F-fluciclovine detection rate (DR) from ≥25 patients with recurrent prostate cancer were sought. Proceedings of relevant meetings held from 2018 through Oct 2020 were searched for abstracts meeting criteria.

RESULTS

Searches identified 321 unique articles. In total, nine articles (six papers and three conference abstracts), comprising a total of 850 patients met inclusion criteria. Most studies (n = 6) relied on ASTRO-Phoenix Criteria, EAU-ESTRO-SIOG, and/or ASTRO-AUA guidelines to identify patients with biochemical recurrence. Patients' PSA levels ranged from 0.02-301.7 ng/mL (median level per study, 0.34-4.10 ng/mL [n = 8]). Approximately 64% of patients had undergone prostatectomy, but three studies focused solely on post-prostatectomy patients. Adherence to imaging protocol guidelines was heterogeneous, with variance seen in administered activity, uptake and scan times. Overall patient-level DR varied between studies from 26% to 83%, with 78% of studies reporting a DR > 50%. DR was proportional to PSA, but even at PSA < 0.5 ng/mL DR of up to 53% were reported. Prostate/bed DR (n = 7) ranged from 18% to 78% and extra-prostatic rates (n = 6) from 8% to 72%. Pelvic node and bone lesion DR ranged from 8% to 47% and 0% to 26%, respectively (n = 5). 18F-Fluciclovine PET/CT was shown to impact patient management and outcomes. Two studies reported 59-63% of patients to have a management change post-scan. A further study showed significant increase in failure-free survival following 18F-fluciclovine-guided compared with conventional imaging-guided radiotherapy planning.

CONCLUSIONS

18F-Fluciclovine PET/CT shows good performance in patients with recurrent prostate cancer leading to measurable clinical benefits. Careful adherence to recommended imaging protocols may help optimize DR.

PET Imaging for Prostate Cancer

The role of PET imaging with ¹¹C-choline and ¹⁸F-fluciclovine in evaluating patients with prostate cancer (PCa) has become more important over the years and has been incorporated into the NCCN guidelines. A new generation of PET radiotracers targeting the prostate-specific membrane antigen (PSMA) is widely used outside the United States to evaluate patients with primary PCa and PCa recurrence. PET imaging influences treatment planning and demonstrates a significantly higher disease detection rate than conventional imaging such as computed tomography and MR imaging. Early data indicate that using PET radiotracers such as ¹⁸F-fluciclovine and PSMA improves patient outcomes. 68-Ga-PSMA-11 and 18F-DCFPyL-PET/CT were recently approved by the US Food & Drug Administration (FDA) for clinical use. Other PSMA radiotracers, including fluorinated variants, will likely gain FDA approval in the not-too-distant future.

18F-fluciclovine PET/CT detection of biochemical recurrent prostate cancer in patients with PSA levels <2.00 ng/mL

OBJECTIVE

To establish the detection rate of prostate cancer recurrence following definitive therapy by 18F-fluciclovine PET/computed tomography (CT) in patients with biochemical recurrence (BCR) and prostate-specific antigen (PSA) levels less than 2.00 ng/mL.

METHODS

In this retrospective study, 78 patients with a PSA level of less than 2.00 ng/mL were selected from the 211 patients who underwent at least one 18F-fluciclovine PET/CT scan at our institution for the detection of biochemical recurrent prostate cancer between April 2017 and December 2018. Inherent differences in the characteristics of patients with and without a positive scan were investigated for possible associations using multivariable analysis.

RESULTS

One or more positive sites of recurrence were identified in 44 out of 78 patients (56.4%). Patients with a Gleason score between 8 and 10 were more likely to have a positive scan compared to patients with Gleason scores of 6-7 [adjusted odds ratio: 3.53, 95% confidence interval (1.13-10.99), P = 0.03]. No other significant association was found between PSA, T classification, and detection rate.

CONCLUSION

18F-fluciclovine PET/CT demonstrated a detection rate of 56.4% among patients with a PSA below 2.0 ng/mL. The results of this study support the use of 18F-fluciclovine PET/CT for the detection of recurrent prostate cancer at lower PSA levels, even at PSA levels less than 0.5 ng/mL.

The Diagnostic Role of 18F-Choline, 18F-Fluciclovine and 18F-PSMA PET/CT in the Detection of Prostate Cancer With Biochemical Recurrence: A Meta-Analysis

Background

Diagnosing the biochemical recurrence (BCR) of prostate cancer (PCa) is a clinical challenge, and early detection of BCR can help patients receive optimal treatment. We conducted a meta-analysis to define the diagnostic accuracy of PET/CT using ¹⁸F-labeled choline, fluciclovine, and prostate-specific membrane antigen (PSMA) in patients with BCR.

Methods

Multiple databases were searched until March 30, 2021. We included studies investigating the diagnostic accuracy of ¹⁸F-choline, ¹⁸F-fluciclovine, and ¹⁸F-PSMA PET/CT in patients with BCR. The pooled sensitivity, specificity, and detection rate of ¹⁸F-labeled tracers were calculated with a random-effects model.

Results

A total of 46 studies met the included criteria; 17, 16, and 13 studies focused on ¹⁸F-choline, fluciclovine, and PSMA, respectively. The pooled sensitivities of ¹⁸F-choline and ¹⁸F-fluciclovine were 0.93 (95% CI, 0.85–0.98) and 0.80 (95% CI, 0.65–0.897), and the specificities were 0.91 (95% CI, 0.73–0.97) and 0.66 (95% CI, 0.50–0.79), respectively. The pooled detection rates of ¹⁸F-labeled choline, fluciclovine and PSMA were 66, 74, and 83%, respectively. Moreover, the detection rates of ¹⁸F-labeled choline, fluciclovine, and PSMA were 35, 23, and 58% for a PSA level less than 0.5 ng/ml; 41, 46, and 75% for a PSA level of 0.5–0.99 ng/ml; 62, 57, and 86% for a PSA level of 1.0–1.99 ng/ml; 80, 92, and 94% for a PSA level more than 2.0 ng/ml.

Conclusion

These three ¹⁸F-labeled tracers are promising for detecting BCR in prostate cancer patients, with ¹⁸F-choline showing superior diagnostic accuracy. In addition, the much higher detection rates of ¹⁸F-PSMA showed its superiority over other tracers, particularly in low PSA levels.

Systematic Review Registration

PROSPERO, identifier CRD42020212531.

A bicentric retrospective analysis of clinical utility of 18F-fluciclovine PET in biochemically recurrent prostate cancer following primary radiation therapy: is it helpful in patients with a PSA rise less than the Phoenix criteria?

PURPOSE

¹⁸F-Fluciclovine PET imaging has been increasingly used in the restaging of prostate cancer patients with biochemical recurrence (BCR); however, its clinical utility in patients with low prostate-specific antigen (PSA) levels following primary radiation therapy has not been well-studied. This study aims to determine the detection rate and diagnostic accuracy of ¹⁸F-fluciclovine PET and the patterns of prostate cancer recurrence in patients with rising PSA after initial radiation therapy, particularly in patients with PSA levels below the accepted Phoenix definition of BCR (PSA nadir +2 ng/mL).

METHODS

This retrospective study included patients from two tertiary institutions who underwent ¹⁸F-fluciclovine PET scans for elevated PSA level following initial external beam radiation therapy, brachytherapy, and/or proton therapy. Logistic regression and receiver operating characteristic (ROC) curve analyses were performed to determine the diagnostic accuracy of ¹⁸F-fluciclovine PET and associations of PSA kinetic parameters with ¹⁸F-fluciclovine PET outcome.

RESULTS

One hundred patients were included in this study. The overall detection rate on a patient-level was 79% (79/100). ¹⁸F-Fluciclovine PET was positive in 62% (23/37) of cases with PSA below the Phoenix criteria. The positive predictive value of ¹⁸F-fluciclovine PET was 89% (95% CI: 80-94%). In patients with PSA below the Phoenix criteria, the PSA velocity had the highest predictive value of ¹⁸F-fluciclovine PET outcome. PSA doubling time (PSADT) and PSA velocity were associated with the presence of extra-pelvic metastatic disease.

CONCLUSION

¹⁸F-Fluciclovine PET can identify recurrent disease at low PSA level and PSA rise below accepted Phoenix criteria in patients with suspected BCR after primary radiation therapy, particularly in patients with low PSADT or high PSA velocity. In patients with low PSADT or high PSA velocity, there is an increased probability of extra-pelvic metastases. Therefore, these patients are more likely to benefit from PET/CT or PET/MRI than pelvic MRI alone.

Role of 18F-Fluciclovine and Prostate-Specific Membrane Antigen PET/CT in Guiding Management of Oligometastatic Prostate Cancer: AJR Expert Panel Narrative Review

Twenty-five years ago, oligometastatic disease was proposed as an intermediary clinical state of cancer with unique implications for therapies that may impact cancer evolution and patient outcome. Identification of limited metastases that are potentially amenable to targeted therapies fundamentally depends on the sensitivity of diagnostic tools, including new-generation imaging methods. For men with biochemical recurrence after definitive therapy of the primary prostate cancer, PET/CT using either the FDA-approved radiolabeled amino acid analogue ¹⁸F-fluciclovine or investigational radiolabeled agents targeting prostate-specific membrane antigen (PSMA) enables identification of early metastases at lower serum PSA levels than was previously feasible using conventional imaging. Evidence supports PSMA PET/CT as the most sensitive imaging modality available for identifying disease sites in oligometastatic prostate cancer. PSMA PET/CT will likely become the modality of choice after regulatory approval and will drive the development of trials of emerging metastasis-directed therapies such as stereotactic ablative body radiation and radioguided surgery. Indeed, numerous ongoing or planned clinical trials are studying advances in management of oligometastatic prostate cancer based on this heightened diagnostic capacity. In this rapidly evolving clinical environment, radiologists and nuclear medicine physicians will play major roles in facilitating clinical decision making and management of patients with oligometastatic prostate cancer.

Salvage Radiotherapy Management Decisions in Postprostatectomy Patients with Recurrent Prostate Cancer Based on 18F-Fluciclovine PET/CT Guidance

Imaging with novel PET radiotracers has significantly influenced radiotherapy decision making and radiation planning in patients with recurrent prostate cancer (PCa). The purpose of this analysis was to report the final results for management decision changes based on ¹⁸F-fluciclovine PET/CT findings and determine whether the decision change trend remained after completion of accrual. Methods: Patients with detectable prostate-specific antigen (PSA) after prostatectomy were randomized to undergo either conventional imaging (CI) only (arm A) or CI plus ¹⁸F-fluciclovine PET/CT (arm B) before radiotherapy. In arm B, positivity rates on CI and ¹⁸F-fluciclovine PET/CT for detection of recurrent PCa were determined. Final decisions on whether to offer radiotherapy and whether to include only the prostate bed or also the pelvis in the radiotherapy field were based on ¹⁸F-fluciclovine PET/CT findings. Radiotherapy decisions before and after ¹⁸F-fluciclovine PET/CT were compared. The statistical significance of decision changes was determined using the Clopper-Pearson (exact) binomial method. Prognostic factors were compared between patients with and without decision changes. Results: All 165 patients enrolled in the study had standard-of-care CI and were initially planned to receive radiotherapy. Sixty-three of 79 (79.7%) patients (median PSA, 0.33 ng/mL) who underwent ¹⁸F-fluciclovine PET/CT (arm B) had positive findings. ¹⁸F-Fluciclovine PET/CT had a significantly higher positivity rate than CI did for the whole body (79.7% vs. 13.9%; P < 0.001), prostate bed (69.6% vs. 5.1%; P < 0.001), and pelvic lymph nodes (38.0% vs. 10.1%; P < 0.001). Twenty-eight of 79 (35.4%) patients had the overall radiotherapy decision changed after ¹⁸F-fluciclovine PET/CT; in 4 of 79 (5.1%), the decision to use radiotherapy was withdrawn because of extrapelvic disease detected on ¹⁸F-fluciclovine PET/CT. In 24 of 75 (32.0%) patients with a final decision to undergo radiotherapy, the radiotherapy field was changed. Changes in overall radiotherapy decisions and radiotherapy fields were statistically significant (P < 0.001). Overall, the mean PSA at PET was significantly different between patients with and without radiotherapy decision changes (P = 0.033). Conclusion: ¹⁸F-Fluciclovine PET/CT significantly altered salvage radiotherapy decisions in patients with recurrent PCa after prostatectomy. Further analysis to determine the impact of ¹⁸F-fluciclovine PET/CT guidance on clinical outcomes after radiotherapy is in progress.

The Clinical Utility of 18F-Fluciclovine PET/CT in Biochemically Recurrent Prostate Cancer: an Academic Center Experience Post FDA Approval

PURPOSE

To evaluate the diagnostic performance and clinical utility of ¹⁸F-fluciclovine PET/CT in patients with biochemical recurrence (BCR) of prostate cancer (PC).

METHODS

¹⁸F-Fluciclovine scans of 165 consecutive men with BCR after primary definitive treatment with prostatectomy (n = 102) or radiotherapy (n = 63) were retrospectively evaluated. Seventy patients had concurrent imaging with at least one other conventional modality (CT (n = 31), MRI (n = 31), or bone scan (n = 26)). Findings from ¹⁸F-fluciclovine PET were compared with those from conventional imaging modalities. The positivity rate and impact of ¹⁸F-fluciclovine PET on patient management were recorded. In 33 patients who underwent at least one other PET imaging (¹⁸F-NaF PET/CT (n = 12), ⁶⁸Ga-PSMA11 PET/CT (n = 5), ¹⁸F-DCFPyL PET/CT (n = 20), and ⁶⁸Ga-RM2 PET/MRI (n = 5)), additional findings were evaluated.

RESULTS

The overall positivity rate of ¹⁸F-fluciclovine PET was 67 %, which, as expected, increased with higher prostate-specific antigen (PSA) levels (ng/ml): 15 % (PSA < 0.5), 50 % (0.5 ≤ PSA < 1), 56 % (1 ≤ PSA < 2), 68 % (2 ≤ PSA < 5), and 94 % (PSA ≥ 5), respectively. One hundred and two patients (62 %) had changes in clinical management based on ¹⁸F-fluciclovine PET findings. Twelve of these patients (12 %) had lesion localization on ¹⁸F-fluciclovine PET, despite negative conventional imaging. Treatment plans of 14 patients with negative ¹⁸F-fluciclovine PET were changed based on additional PET imaging with a different radiopharmaceutical.

CONCLUSION

¹⁸F-Fluciclovine PET/CT remains a useful diagnostic tool in the workup of patients with BCR PC, changing clinical management in 62 % of participants in our cohort.

Recent updates and developments in PET imaging of prostate cancer

A number of positron emission tomography (PET) radiotracers have been developed to improve the sensitivity and specificity of imaging for prostate cancer. These radiotracers include the bone-seeking agent Na¹⁸F as well as more tumor-specific compounds such as ¹¹C-choline and ¹⁸F-fluciclovine. In this review, we will discuss the advantages and disadvantages of these PET radiotracers for the imaging of men with prostate cancer across a range of clinical contexts. We will also touch upon radiotracers in late clinical development that have not gained regulatory approval, including those targeted against prostate-specific membrane antigen (PSMA) and gastrin-releasing peptide receptor (GRPR).

Salvage Pelvic Lymph Node Dissection and Current State of Imaging for Recurrent Prostate Cancer: Does a Standard Exist?

PURPOSE OF REVIEW

We aim to evaluate the efficacy of salvage lymph node dissection (SLND) for nodal recurrent prostate cancer after primary treatment. We also provide a review of the diagnostic performance of next-generation sequencing (next-generation imaging (NGI)) radiotracers in the salvage setting.

RECENT FINDINGS

Most studies evaluating SLND include a heterogeneous population with a small sample size and are retrospective in design. The 5-year clinical recurrence-free and cancer-specific survival following SLND are 26-52% and 57-89%, respectively, among prospective studies. NGI improves accuracy in detecting nodal recurrence compared to conventional CT, with PMSA PET-CT showing the most promise. However, limited studies exist comparing imaging modalities and performance is variable at low PSA values. SLND is a promising treatment option, but more prospective data are needed to determine the ideal surgical candidate and long-term oncologic outcomes. More studies comparing different NGI are needed to determine the best imaging modality in patients who may be candidates for salvage treatment.

Positron emission tomography (PET) radiotracers for prostate cancer imaging

Imaging plays an increasing role in prostate cancer diagnosis and staging. Accurate staging of prostate cancer is required for optimal treatment planning. In detecting extraprostatic cancer and sites of early recurrence, traditional imaging methods (computed tomography, magnetic resonance imaging, radionuclide bone scan) have suboptimal performance. This leaves a gap between known disease recurrence as indicated by rising prostate-specific antigen and the ability to localize the recurrence on imaging. Novel positron emission tomography (PET) agents including radiolabeled choline, fluciclovine (¹⁸F-FACBC), and agents targeting prostate-specific membrane antigen are being developed and tested to increase diagnostic performance of non-invasive prostate cancer localization. When combined with CT or MRI, these tracers offer a combination of functional information and anatomic localization that is superior to conventional imaging methods. These PET radiotracers have varying mechanisms and excretion patterns affecting their pharmacokinetics and diagnostic performance, which will be reviewed in this article.

Utility of 18F-Fluciclovine PET/CT for Detecting Prostate Cancer Recurrence in Patients With Low (< 1 ng/mL) or Very Low (< 0.3 ng/mL) Prostate-Specific Antigen Levels

OBJECTIVE. We reviewed a retrospective series of 126 ¹⁸F-fluciclovine PET/CT studies of patients with biochemically recurrent prostate cancer at low (< 1 ng/mL) and very low (< 0.3 ng/mL) prostate-specific antigen (PSA) levels. CONCLUSION. The rate of PET/CT positivity was 33% (15/46) in patients with low PSA levels and 0% (0/17) in patients with very low PSA levels. Our results suggest that ¹⁸F-fluciclovine PET/CT can be helpful for localizing recurrence in patients with PSA levels between 0.3 and 1 ng/mL and that ¹⁸F-fluciclovine PET/CT is not recommended in patients with PSA levels less than 0.3 ng/mL.