Value of [11C]choline-positron emission tomography for re-staging prostate cancer: a comparison with [18F]fluorodeoxyglucose-positron emission tomography

Role of 18F-choline and 18F-fluorodeoxyglucose positron emission tomography in combination with magnetic resonance imaging in brachytherapy planning for locally advanced cervical cancer: A pilot study

Background and purpose

This pilot study aims to describe the advantages of combining metabolic and anatomic imaging modalities in brachytherapy (BT) planning for locally advanced cervical cancer (LACC) and to evaluate the supplementary value of Fluoro(F)-Choline positron emission tomography/computed tomography (PET/CT) in comparison to 18F-fluorodeoxyglucose (FDG) in this setting.

Materials and methods

A prospective cohort of six patients with LACC was included in this study. Each patient underwent BT planning CT scan, magnetic resonance imaging (MRI), and both FDG and F-Choline PET/CT scans on the same day, with BT applicators in place. Patients were treated according to the standard of care. Metabolic target volumes (TV) were generated retrospectively and compared with the anatomic volumes using Dice coefficients and absolute volume comparison.

Results

The threshold at which the metabolic and anatomic volumes were the most concordant was found to be 35% maximum standardized uptake value (SUV max) for both PET/CT scans. Amongst the six patients in this cohort, three in the FDG cohort and four in the F-Choline cohort were found to have more than ten percent ratio of excess (increase) in their MRI gross tumor volumes (GTV) when incorporating the metabolic information from the PET/CT scans. However, no significant changes were needed in the high risk-clinical target volumes (CTVHR) for both PET tracers.

Conclusions

FDG and F-Choline PET/CT scans can substantially modify the BT GTV on MRI, without affecting the CTVHR. F-Choline is potentially more informative than FDG in assessing residual TV, particularly in cases with significant post-radiation inflammatory changes.

Comparison of PET/CT and MRI in the Diagnosis of Bone Metastasis in Prostate Cancer Patients: A Network Analysis of Diagnostic Studies

BACKGROUND

Accurate diagnosis of bone metastasis status of prostate cancer (PCa) is becoming increasingly more important in guiding local and systemic treatment. Positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI) have increasingly been utilized globally to assess the bone metastases in PCa. Our meta-analysis was a high-volume series in which the utility of PET/CT with different radioligands was compared to MRI with different parameters in this setting.

MATERIALS AND METHODS

Three databases, including Medline, Embase, and Cochrane Library, were searched to retrieve original trials from their inception to August 31, 2019 according to the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. The methodological quality of the included studies was assessed by two independent investigators utilizing Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2). A Bayesian network meta-analysis was performed using an arm-based model. Absolute sensitivity and specificity, relative sensitivity and specificity, diagnostic odds ratio (DOR), and superiority index, and their associated 95% confidence intervals (CI) were used to assess the diagnostic value.

RESULTS

Forty-five studies with 2,843 patients and 4,263 lesions were identified. Network meta-analysis reveals that 68Ga-labeled prostate membrane antigen (68Ga-PSMA) PET/CT has the highest superiority index (7.30) with the sensitivity of 0.91 and specificity of 0.99, followed by 18F-NaF, 11C-choline, 18F-choline, 18F-fludeoxyglucose (FDG), and 18F-fluciclovine PET/CT. The use of high magnetic field strength, multisequence, diffusion-weighted imaging (DWI), and more imaging planes will increase the diagnostic value of MRI for the detection of bone metastasis in prostate cancer patients. Where available, 3.0-T high-quality MRI approaches 68Ga-PSMA PET/CT was performed in the detection of bone metastasis on patient-based level (sensitivity, 0.94 vs. 0.91; specificity, 0.94 vs. 0.96; superiority index, 4.43 vs. 4.56).

CONCLUSIONS

68Ga-PSMA PET/CT is recommended for the diagnosis of bone metastasis in prostate cancer patients. Where available, 3.0-T high-quality MRI approaches 68Ga-PSMA PET/CT should be performed in the detection of bone metastasis.

The Evolving Role of 18F-FDG PET/CT in Diagnosis and Prognosis Prediction in Progressive Prostate Cancer

Positron emission tomography/computed tomography (PET/CT) is widely used in prostate cancer to evaluate the localized tumor burden and detect symptomatic metastatic lesions early. ¹⁸F-FDG is the most used tracer for oncologic imaging, but it has limitations in detecting early-stage prostate cancer. ⁶⁸Ga-PSMA is a new tracer that has high specificity and sensibility in detecting local and metastatic tumors. But with the progression of prostate cancer, the enhancement of glucose metabolism in progressive prostate cancer provides a chance for ¹⁸F-FDG. This review focuses on PET/CT in the detection and prognosis of prostate cancer, summarizing the literature on ¹⁸F-FDG and ⁶⁸Ga-PSMA in prostate cancer and highlighting that ¹⁸F-FDG has advantages in detecting local recurrence, visceral and lymph node metastases compared to ⁶⁸Ga-PSMA in partial progressive prostate cancer and castration-resistant prostate cancer patients. We emphasize ¹⁸F-FDG PET/CT can compensate for the weakness of ⁶⁸Ga-PSMA PET/CT in progressive prostate cancer.

Effect of Salvage Radiotherapy and Endocrine Therapy on Patients with Biochemical Recurrence After Prostate Cancer Operation- a Meta‑Analysis

CONTEXT

Several studies reported the application of androgen deprivation therapy and radiotherapy in patients with biochemical recurrence after prostate cancer operation.

OBJECTIVE

To perform a systematic review and meta-analysis evaluating of endocrine therapy and radiotherapy in patients with biochemical recurrence after prostate cancer surgery. The primary end point was biochemical progression-free survival (bPFS). Secondary end point was overall survival (OS).

METHODS

A systematic review of PubMed/Medline, Embase, and Cochrane databases to identify relevant studies published in English up to March 2020. Twelve studies were selected for inclusion.

RESULTS

There were 11 studies included in the present study. Including two randomized controlled trials and nine cohort studies. The meta-analysis shows a significant bPFS benefit from androgen deprivation therapy and radiotherapy in patients with biochemical recurrence after prostate cancer operation. (hazard ratio [HR]: 0.57; 95% confidence interval CI, 0.52-0.63; p < .001). For patients with GS < 7 and low-risk patients, combined treatment can have a benefit for BPFs (HR: 0.53; 95% CI, 0.37-0.76; HR: 0.58; 95% CI, 0.36-0.93). Androgen deprivation therapy and radiotherapy in patients with biochemical recurrence was associated with a slightly OS improvement (HR: 0.73; 95% CI, 0.57-0.93; p = 0.01).

CONCLUSIONS

Compared with salvage radiotherapy alone, This meta-analysis shows a significant bPFS benefit from endocrine therapy combined with salvage radiotherapy in patients with biochemical recurrence after prostate cancer operation. And benefit more for high-risk groups. However, there was no significant benefit in group GS ≥ 8. It shows a slightly OS benefit from endocrine therapy combined with salvage radiotherapy in patients with biochemical recurrence.

Kinetic isotope effects and synthetic strategies for deuterated carbon-11 and fluorine-18 labelled PET radiopharmaceuticals

The deuterium labelling of pharmaceuticals is a useful strategy for altering pharmacokinetic properties, particularly for improving metabolic resistance. The pharmacological effects of such metabolites are often assumed to be negligible during standard drug discovery and are factored in later at the clinical phases of development, where the risks and benefits of the treatment and side-effects can be wholly assessed. This paradigm does not translate to the discovery of radiopharmaceuticals, however, as the confounding effects of radiometabolites can inevitably show in preliminary positron emission tomography (PET) scans and thus complicate interpretation. Consequently, the formation of radiometabolites is crucial to take into consideration, compared to non-radioactive metabolites, and the application of deuterium labelling is a particularly attractive approach to minimise radiometabolite formation. Herein, we provide a comprehensive overview of the deuterated carbon-11 and fluorine-18 radiopharmaceuticals employed in PET imaging experiments. Specifically, we explore six categories of deuterated radiopharmaceuticals used to investigate the activities of monoamine oxygenase (MAO), choline, translocator protein (TSPO), vesicular monoamine transporter 2 (VMAT2), neurotransmission and the diagnosis of Alzheimer's disease; from which we derive four prominent deuteration strategies giving rise to a kinetic isotope effect (KIE) for reducing the rate of metabolism. Synthetic approaches for over thirty of these deuterated radiopharmaceuticals are discussed from the perspective of deuterium and radioisotope incorporation, alongside an evaluation of the deuterium labelling and radiolabelling efficacies across these independent studies. Clinical and manufacturing implications are also discussed to provide a more comprehensive overview of how deuterated radiopharmaceuticals may be introduced to routine practice.

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.

Non-FDG PET/CT

The major applications for molecular imaging with PET in clinical practice concern cancer imaging. Undoubtedly, 18F-FDG represents the backbone of nuclear oncology as it remains so far the most widely employed positron emitter compound. The acquired knowledge on cancer features, however, allowed the recognition in the last decades of multiple metabolic or pathogenic pathways within the cancer cells, which stimulated the development of novel radiopharmaceuticals. An endless list of PET tracers, substantially covering all hallmarks of cancer, has entered clinical routine or is being investigated in diagnostic trials. Some of them guard significant clinical applications, whereas others mostly bear a huge potential. This chapter summarizes a selected list of non-FDG PET tracers, described based on their introduction into and impact on clinical practice.

Diagnostic Performance of [18F]Fluorocholine and [68Ga]Ga-PSMA PET/CT in Prostate Cancer: A Comparative Study

The current study endeavored to closely compare the detection rate of 68-Gallium labelled prostate-specific membrane antigen ([⁶⁸Ga]Ga-PSMA) versus [¹⁸F]Fluorocholine in men with prostate cancer (PC), to investigate the benefits and pitfalls of each modality in the setting of various patient characteristics. We retrospectively analyzed 29 biopsy-proven PC patients in two categories, staging and restaging, who underwent both scans within a maximum of 30 days of each other. Variables including patient demographics, prostate specific antigen (PSA) level, Gleason score, clinical course, and following treatments were recorded. The number and location of suspicious lesions as well as uptake values were noted. A total of 148 suspicious lesions were detected, of which 70.9% (105/148) were concordantly visualized in both imaging modalities. [⁶⁸Ga]Ga-PSMA positron emission tomography/computed tomography (PET/CT) revealed a higher number of metastatic lesions per patients (91% vs 78%). The mean of maximum standardized uptake value (SUV max) in concordant lesions was significantly higher in [⁶⁸Ga]Ga-PSMA compared to [¹⁸F]Fluorocholine PET/CT (14.6 ± 8.44 vs. 6.9 ± 3.4, p = 0.001). Discordant lesions were detected by both modalities, but more frequently by [⁶⁸Ga]Ga-PSMA PET/CT (20.3% in [⁶⁸Ga]Ga-PSMA versus 8.8% by [¹⁸F]Fluorocholine PET/CT). In patients with PSA levels below 1.0 ng/mL and <2.0 ng/mL, [¹⁸F]Fluorocholine PET/CT detection rate was half (57% and 55%, respectively) that of [⁶⁸Ga]Ga-PSMA PET/CT. Tumor, nodes and metastases (TNM) staging, and subsequently patient management, was only influenced in 4/29 patients (14%), particularly by [⁶⁸Ga]Ga-PSMA PET/CT with PSA values under 0.5 ng/mL. [⁶⁸Ga]Ga-PSMA PET/CT revealed superior diagnostic performance to [¹⁸F]Fluorocholine PET/CT in staging and restaging of PC patients, especially in cases with low PSA levels. However, in a few hormone resistant high-risk PC patients, [¹⁸F]Fluorocholine PET/CT may improve overall diagnostic accuracy.

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.

Standardization of acquisition protocols using PET/CT with 18F-Choline in prostate cancer

AIM

To standardize acquisition protocols for ¹⁸F-Choline PET/CT to prevent from urine interference, to determine the best time point for the whole-body study, and to assess whether "dual point" acquisition allows for differentiating malignant vs. benign lesions.

METHODS

One hundred consecutive patients with prostate cancer were prospectively studied. Immediately after ¹⁸F-Choline injection, a pelvis study was acquired, and a whole-body was subsequently obtained 1 and 2 hours p.i. Mean SUVmax was obtained in regions and for every sequential imaging. Mean analysis (χ²) and SUV percentage change (2/1 hours; 1 hours/0 min) were obtained. Metabolic pattern dynamics were assessed: accumulative vs. clearance. Patient follow-up after therapy and directed classification whenever ethically possible were performed.

RESULTS

Fifty-three prostate foci, without disturbing urinary activity was ever found on early images. Accumulative pattern in 42, with percentage increase was: 0 min/1 hour: +16.7% (χ²0.94); 1/2 hours: +10,0% (χ² 0.83). Clearance pattern in 11, with percentage decrease: 0 min/1 hour: -21.4% (χ²0.91): -7.7% (χ²0.85), corresponding in 7 to initial staging and in 4 post-radiotherapy biochemical recurrence. Every infradiaphragmatic uptake (n: 24) showed accumulative pattern, with percentage increase of +9.1% (χ²0.97), all of them depicted on early imaging. As for 12 supradiaphragmantic uptake, 8 of them showed clearance pattern with percentage decrease: -13.0% (χ²0.95). Accumulative pattern showed in 4 of them with percentage increase +13.0% (χ² 0.96), thus being assessed as invasive/malignant. Every bone uptake (n: 18) showed accumulative pattern, with percentage increase: +17.1% (χ²0.95), all of them depicted on 1 hour imaging.

CONCLUSIONS

As for prostate assessment is concerned, dual point at 0 min/1 hour proved to be the best procedure. As for supradiaphragmatic lymph-nodes detection, dual point with 1/2 hours performed best. As for infradiaphragmatic and bone involvement, as well as for inconclusive findings, the 2 hour imaging increased our diagnostic confidence.

Cavitary lung metastasis as relapse of prostate cancer

Prostate cancer is the most common non-cutaneous malignancy diagnosed in men. It usually metastasizes to bone as osteoblastic lesions on radiographs and regional lymph nodes, and uncommonly to lung, liver and brain. Metastatic prostate cancer recurrence after definitive local therapy can occur in any tissue. The role of fine needle aspiration cytology (FNAC) for diagnosis of metastatic malignancies is well established in literature. We describe a 74 years old male, previously treated for localized prostate cancer, admitted to our Department after total body computed tomography revealed multiple irregular lung lesions some of which had an excavated appearance.

Usefulness of 18F-fluorocoline PET/CT in prostate cancer patients with biochemical recurrence: Influence of PSA kinetics and hormone therapy

PURPOSE

To evaluate the capacity of 18f-fluorocholine positron emission tomography/computed tomography (FCH PET/CT) to detect biochemical recurrence of prostate cancer and to determine the correlation with PSA kinetics and influence of antiandrogen hormone therapy.

PATIENTS AND METHODS

Observational and retrospective study, which included patients with prostate cancer and criteria for biochemical recurrence and/or resistance to castration, according to the European Association of Urology. FCH PET/CT results were classified as positive or negative, using as gold standard the pathology report, findings of other imaging test, and/or clinical follow-up results. The correlation between FCH PET/CT and PSA kinetics (PSA at the time of exploration [PSA-trigger], doubling time [PSAdt] and velocity [PSAva]) was studied and the influence of hormone therapy was analysed.

RESULTS

The study included 203 patients. The FCH PET/CT detection rate was 43.3%. The group of patients with FCH PET/CT positive showed more aggressive PSA kinetics (PSAdt: 7.5 months and PSAva 8.37±14.8ng/ml/a) than the FCH PET/CT negative group (PSAdt: 14.5±7.6 months and PSAva: 1.8±3.7ng/ml/a). The detection rate of FCH PET/CT in the subgroup with castration resistance was 89.1%, significantly higher than in the group with radical treatment at 29.9%, p<.001.

CONCLUSIONS

FCH PET/CT is useful to detect biochemical recurrence of prostate cancer, especially in patients who receive hormone therapy or more aggressive PSA kinetics.

F18-choline/C11-choline PET/CT thyroid incidentalomas

INTRODUCTION

Thyroid incidentaloma is defined as a thyroid lesion incidentally and newly detected by imaging techniques performed for an unrelated purpose and especially for a non-thyroid disease. Aim of this review is to evaluate the prevalence and clinical significance of focal incidental radiolabelled choline uptake in the thyroid gland (CTI) revealed by PET or PET/CT.

METHODS

A comprehensive computer literature search of the PubMed/MEDLINE, Scopus, and Embase databases was conducted to find relevant published articles about the prevalence and clinical significance of CTIs detected by PET or PET/CT in patients studied for other oncologic purposes.

RESULTS

Fifteen articles (14 case reports, one retrospective study on a larger population sample) were included in the systematic review. Considering the case reports, 7/14 CTIs were benign and 7/14 malignant. In the retrospective study on a larger population sample, 14/15 CTIs which underwent further investigations were benign.

CONCLUSION

Despite very rare but probably underestimated, CTIs frequently signal in the presence of unexpected lesions in the thyroid that differ from the indicated reason for which the patient was initially scanned, and the risk of malignancy is not negligible.

11C-choline PET/CT predicts survival in prostate cancer patients with PSA < 1 NG/ml

PURPOSE

The main drawback of ¹¹C-choline PET/CT for restaging prostate cancer (PCa) patients with biochemical failure is the relatively low positive detection rate for prostate specific antigen (PSA) < 1 ng/ml. This study assessed whether ¹¹C-choline PET/CT predicts survival in PCa patients with PSA < 1 ng/ml.

METHODS

This retrospective study included 210 PCa patients treated with radical prostatectomy who underwent ¹¹C-choline PET/CT from December 1, 2004 to July 31, 2007 due to biochemical failure. PCa-specific survival was estimated using Kaplan-Meier curves. Cox regression analysis was used to evaluate the association between clinicopathologic variables and PCa-specific survival. PCa-specific survival was computed as the interval from radical prostatectomy to PCa-specific death.

RESULTS

Median follow-up after radical prostatectomy was 6.9 years (95% confidence interval, CI, 2.0-14.5 years). ¹¹C-choline PET/CT was positive in 20.5% of patients. Median PCa-specific survival was 13.4 years (95% CI, 9.9-16.8 years) in patients with positive ¹¹C-choline PET/CT, and it was not achieved in patients with negative ¹¹C-choline PET/CT (log-rank, chi-square = 15.0, P < 0.001). Ten-year survival probabilities for patients with negative ¹¹C-choline PET/CT and for patients with positive ¹¹C-choline PET/CT were 86.0% (95% CI: 80.7%-91.3%) and 63.6% (95% CI: 54.5-72.7%). At multivariate analysis, only ¹¹C-choline PET/CT significantly predicted PCa-specific survival (hazard ratio = 2.54, 95% CI, 1.05-6.13, P = 0.038). Patients with pathological ¹¹C-choline uptake in the prostatic bed or in pelvic lymph nodes had longer PCa-specific survival in comparison to patients with pathological tracer uptake in the skeleton (log-rank: chi-square = 27.4, P < 0.001).

CONCLUSION

Despite the relatively low positive detection rate for PSA < 1 ng/ml, positive ¹¹C-choline PET/CT predicts PCa-specific survival in this low PSA range. As long as more sensitive radiotracers, such as ⁶⁸Ga-PSMA-11, do not become more widely available, these results might support a broader use of radiolabeled choline in restaging PCa for PSA < 1 ng/ml.

Intraindividual comparison of 68Ga-DOTATATE PET / CT vs 11C-Choline PET / CT in patients with prostate cancer in biochemical relapse: in vivo evaluation of the expression of somatostatin receptors

BACKGROUND AND OBJECTIVES

To prospectively compare the detection rate of ⁶⁸Ga-DOTATATE versus ¹¹C-choline PET/CT in patients with prostate cancer in biochemical relapse, and to evaluate somatostatin receptor expression in vivo to plan targeted therapies (¹⁷⁷Lu-DOTATATE).

MATERIAL AND METHODS

We prospectively analysed 64 patients with biochemical relapse (median PSA: 4.25 ng/mL). A PET/CT was performed with ¹¹C-choline, and another with ⁶⁸Ga-DOTATATE. The SUVmax was measured in all lesions. The correlative images, histopathology and/or clinical and biochemical follow-up were taken as the reference standard.

RESULTS

The overall detection rate per patient was 48.43% for ⁶⁸Ga-DOTATATE and 46.87% for ¹¹C-choline. The results were concordant in 53 cases (82.81%). The maximum SUV of ¹¹C-choline was significantly higher than that of ⁶⁸Ga-DOTATATE for all the concordant lesions (n=130): 6.17 (1.7-15.5) versus 4.38 (1.37-26.7), median (range) for each radiotracer, respectively (p < .0001). The sensitivity and specificity values per patient were the same for both techniques: 0.82 (0.65-0.93) and 0.9 (0.73-0.98), respectively. Although the difference was not significant, the sensitivity was lower in patients with lower PSA levels: 0.63 vs. 0.89; p=.13. A significant correlation was found between the SUVmax of both tracers (r = 0.41, n = 130, p <.0001).

CONCLUSIONS

⁶⁸Ga-DOTATATE PET/CT and ¹¹C-choline PET/CT seem to have a high capacity to detect pathological lesions in the assessment of patients with prostate cancer with biochemical relapse. Further studies are required to test the potential complementary value of these PET/CT techniques, and to evaluate the potential role of ⁸Ga-DOTATATE for planning somostatin receptor-mediated therapies (¹⁷⁷Lu-DOTATATE).

Clinical implications of PET/CT in prostate cancer management

Several imaging modalities exist for the investigation of prostate cancer (PCa). From ultrasound to computed tomography (CT) and magnetic resonance imaging (MRI), the role of imaging in detecting lesion foci, staging, and localizing disease after biochemical recurrence (BCR) is expanding. However, many of the conventional imaging modalities are suboptimal, particularly in the detection of metastasis. Positron emission tomography (PET) has recently emerged as a promising tool in PCa management. The ability to develop radiolabeled tracers for functional imaging based on characteristics of PCa cells can potentially provide more insight into management by utilizing key features of those cells, such as metabolic activity, increased proliferation, and receptor expression. 18-flurodeoxyglucose (FDG) is one of the earliest tracers used in PET imaging that takes advantage of increased metabolism of glucose. Its role in PCa has been somewhat limited due to poor resolution and confounders including noise resulting from the proximity of the prostate to the bladder. Choline, a precursor molecule for a major component of the cell membrane, phosphatidylcholine, shows increased uptake in cells with rapid proliferation. When compared to metabolic based imaging techniques with FDG, choline PET/CT was superior. Nevertheless, choline PET/CT was not equivocal to MRI in detection of local disease, but was superior to conventional imaging in localizing metastasis and lymph node metastasis (LNM). Fluciclovine is another novel marker that utilizes the increased proliferation seen in tumor cells. Studies have shown it to be superior to choline PET/CT in PCa management, particularly in patients with BCR. As with choline PET/CT, studies that have assessed the impact of fluciclovine on clinical practice have highlighted the impact of these new tracers on clinical decision making. Most recently, the newest molecular probe targeting prostate specific membrane antigen (PSMA) was developed. It offers higher detection rates compared to choline PET/CT and conventional imaging modalities and has shown promise in LNM and BCR. With the wide range of available PET tracers, this review aims to highlight the role of each in lesion foci detection, primary staging, disease recurrence and explore the potential clinical impact.

Fluciclovine positron emission tomography in the setting of biochemical recurrence following local therapy of prostate cancer

Approximately one in five men will demonstrate biochemical recurrence (BCR) following local therapy for prostate cancer (PCa). Advanced imaging modalities including positron emission tomography (PET) imaging of various radiotracers have become more commonplace to visualize foci of disease recurrence. We performed a systematic review of the literature to describe current evidence in support of 18F-fluciclovine (Axumin) PET imaging in this clinical setting. An English literature search was conducted on PubMed/Medline for original investigations on 18F-fluciclovine PET for PCa. Boolean criteria included the terms: prostate, fluciclovine, FACBC and Axumin. Published articles meeting these criteria and their respective bibliographies and diagnostic modalities were included after review, when appropriate. Our literature review identified 93 articles. Among these, 18 met our inclusion criteria. Evidence suggests 18F-fluciclovine PET imaging is safe, well-tolerated and offers acceptable sensitivity and specificity for the detection of localized intraglandular and extraprostatic PCa foci in the setting of persistence or recurrence after primary treatment. Compared to other available PET radiotracers available, evidence suggests that 18F-fluciclovine may outperform ProstaScint and 11C-choline in this clinical setting. Furthermore, 18F-fluciclovine PET may aid guiding decision-making in regards to salvage therapy planning. Further investigation is warranted to validate these early findings and to further compare this agent to other available radiotracers in this setting.

The utility of PET-based imaging for prostate cancer biochemical recurrence: a systematic review and meta-analysis

INTRODUCTION

Conventional imaging modalities have been poor in characterizing the true extent of disease in men with biochemical recurrence following primary treatment for prostate cancer. Functional imaging with positron emission tomography (PET) has shown promise of being a superior imaging modality. We conducted a systematic review and meta-analysis to define the diagnostic accuracy of PET/CT using 11C-choline, 18F-FACBC, or 68Ga-PSMA in detecting recurrent prostate cancer.

METHODS

We searched multiple databases in line with the preferred reporting items for systematic review and meta-analysis (PRISMA) statement to define the diagnostic accuracy of 11C-choline, 18F-FACBC, or 68Ga-PSMA PET/CT. Only studies secondarily staging participants with biochemical recurrence and those with an appropriate reference standard (pathology, further imaging, and/or clinical response) were eligible for analysis.

RESULTS

Twenty-one studies with 3202 participants met the inclusion criteria. Of these, 11C-choline, 18F-FACBC, and 68Ga-PSMA were the tracer investigated in 16, 5, and 1 studies, respectively. The summary sensitivity for each tracer was 80.9% (95% CI 70.4-88.3%), 79.7% (95% CI 51.9-93.4%), and 76.4% (95% CI 68.3-82.9%), respectively. The corresponding summary specificity was 84.1% (95% CI 70.2-92.2%), 61.9% (95% CI 41.1-79.0%), and 99.8% (95% CI 97.5-100%), respectively. Detection rates ranged between 58.6 and 82.8%. All included studies were judged to be at high risk of bias primarily due to study limitations pertaining to the reference standard.

CONCLUSION

There is a lack of high-quality data to verify the accuracy of PET-based imaging using 11C-choline, 18F-FACBC, or 68Ga-PSMA. The early results are encouraging that these techniques are superior to conventional imaging modalities, which would allow salvage therapies to be optimized.

Comparison of 11C-choline Positron Emission Tomography/Computed Tomography (PET/CT) and Conventional Imaging for Detection of Recurrent Prostate Cancer

We aimed to compare ¹¹C-choline positron emission tomography/computed tomography (PET/CT) with conventional imaging, including pelvic magnetic resonance imaging (MRI), contrast-enhanced chest, abdomen, and pelvic computed tomography (CT), and bone scintigraphy, for prostate cancer restaging. Thirty patients (median prostate-specific antigen [PSA: 11.8 ng/mL]) with suspected recurrent prostate cancer following definitive treatment underwent ¹¹C-choline PET/CT and conventional imaging, including pelvic MRI, contrast-enhanced chest, abdomen, and pelvic CT, and bone scintigraphy. The results were compared with regard to patient- and lesion-based diagnostic performance for local recurrence, and for lymph node and bony metastases using receiver operating characteristic (ROC) analysis and McNemar’s test. Documented local recurrence and node and bony metastases were present in 11 (36.7%), 10 (33.3%), and 17 (56.7%) cases, respectively, of the enrolled patients. Patient-based sensitivity / specificity / accuracy / area under the ROC curve for ¹¹C-choline-PET/CT for diagnosing local recurrence were 90.9% / 94.7% / 93.3% / 0.975 and for conventional imaging were 90.9% / 100% / 96.7% / 1.0. Those who underwent ¹¹C-choline-PET/CT for node metastasis were 90.0% / 95.0% / 93.3% / 0.925 and for conventional imaging were 70.0% / 95.0% / 86.7% / 0.905. Those who underwent ¹¹C-choline-PET/CT for bone metastasis were 94.1% / 92.3% / 93.3% / 0.991 and who underwent conventional imaging were 94.1% / 84.6% / 90.0% / 0.982. No significant differences were observed among them. The lesion-based detection rate of ¹¹C-choline PET/CT for local recurrences and node and bone metastases as compared to conventional imaging was 92.9% (13/14) vs. 92.9% (13/14); 87.1% (27/31) vs. 54.8% (17/31); and 96.9% (219/226) vs. 90.3% (204/226) respectively, with significant differences noted for detection of node and bone lesions (p=0.0044 and p=0.00030, respectively). ¹¹C-choline-PET/CT is more accurate in the detection of recurrent prostate cancer nodes and bony metastatic lesions compared to conventional imaging and has the advantage of restaging the disease in a single step.

68Ga-PSMA and 11C-Choline comparison using a tri-modality PET/CT-MRI (3.0 T) system with a dedicated shuttle

Background

The aim of this study was to prospectively compare the detection rate of ⁶⁸Ga-PSMA versus ¹¹C-Choline in men with prostate cancer with biochemical recurrence and to demonstrate the added value of a tri-modality PET/CT-MRI system.

Methods

We analysed 36 patients who underwent both ¹¹C-Choline PET/CT and ⁶⁸Ga-PSMA PET/CT scanning within a time window of 1-2 weeks. Additionally, for the ⁶⁸Ga-PSMA scan, we used a PET/CT-MRI (3.0 T) system with a dedicated shuttle, acquiring MRI images of the pelvis.

Results

Both scans were positive in 18 patients (50%) and negative in 8 patients (22%). Nine patients were positive with ⁶⁸Ga-PSMA alone (25%) and one with ¹¹C-Choline only (3%). The median detected lesion per patient was 2 for ⁶⁸Ga-PSMA (range 0-93) and 1 for ¹¹C-Choline (range 0-57). Tumour to background ratios in all concordant lesions (n = 96) were higher for ⁶⁸Ga-PSMA than for ¹¹C-Choline (110.3 ± 107.8 and 27.5 ± 17.1, mean ± S.D., for each tracer, respectively P = 0.0001). The number of detected lesions per patient was higher for ¹¹C-Choline in those with PSA ≥ 3.3 ng/mL, while the number of detected lesions was independent of PSA levels for ⁶⁸Ga-PSMA using the same PSA cut-off value. Metastatic pelvic lesions were found in 25 patients (69%) with ⁶⁸Ga-PSMA PET/CT, in 18 (50%) with ¹¹C-Choline PET/CT and in 21 (58%) with MRI (3.0 T). MRI was very useful in detecting recurrence in cases classified as indeterminate by means of PET/CT alone at prostate bed.

Conclusions

In patients with prostate cancer with biochemical recurrence ⁶⁸Ga-PSMA detected more lesions per patient than ¹¹C-Choline, regardless of PSA levels. PET/CT-MRI (3.0 T) system is a feasible imaging modality that potentially adds useful relevant information with increased accuracy of diagnosis.

Combined model-based and patient-specific dosimetry for 18F-DCFPyL, a PSMA-targeted PET agent

PURPOSE

Prostate-specific membrane antigen (PSMA), a type-II integral membrane protein highly expressed in prostate cancer, has been extensively used as a target for imaging and therapy. Among the available PET radiotracers, the low molecular weight agents that bind to PSMA are proving particularly effective. We present the dosimetry results for ¹⁸F-DCFPyL in nine patients with metastatic prostate cancer.

METHODS

Nine patients were imaged using sequential PET/CT scans at approximately 1, 12, 35 and 70 min, and a final PET/CT scan at approximately 120 min after intravenous administration of 321 ± 8 MBq (8.7 ± 0.2 mCi) of¹⁸F-DCFPyL. Time-integrated-activity coefficients were calculated and used as input in OLINDA/EXM software to obtain dose estimates for the majority of the major organs. The absorbed doses (AD) to the eye lens and lacrimal glands were calculated using Monte-Carlo models based on idealized anatomy combined with patient-specific volumes and activity from the PET/CT scans. Monte-Carlo based models were also developed for calculation of the dose to two major salivary glands (parotid and submandibular) using CT-based patient-specific gland volumes.

RESULTS

The highest calculated mean AD per unit administered activity of ¹⁸F was found in the lacrimal glands, followed by the submandibular glands, kidneys, urinary bladder wall, and parotid glands. The S-values for the lacrimal glands to the eye lens (0.42 mGy/MBq h), the tear film to the eye lens (1.78 mGy/MBq h) and the lacrimal gland self-dose (574.10 mGy/MBq h) were calculated. Average S-values for the salivary glands were 3.58 mGy/MBq h for the parotid self-dose and 6.78 mGy/MBq h for the submandibular self-dose. The resultant mean effective dose of ¹⁸F-DCFPyL was 0.017 ± 0.002 mSv/MBq.

CONCLUSIONS

¹⁸F-DCFPyL dosimetry in nine patients was obtained using novel models for the lacrimal and salivary glands, two organs with potentially dose-limiting uptake for therapy and diagnosis which lacked pre-existing models.

Trigger pSA predicting recurrence from positive choline PET/CT with prostate cancer after initial treatment

Purpose

To assess the relationship between the diagnostic accuracy of Choline positron emission tomography/computed tomography (PET/CT) and the trigger prostate-specific antigen (PSA) level in patients with a biochemical recurrence of prostate cancer.

Materials and Methods

A meta-analysis was conducted to synthesize data across multiple studies.

Results

The pooled sensitivity and specificity of choline PET/CT were 82% (95% Confidence Interval (CI):80-84%) and 92% (95%CI: 90-93%), respectively. The pooled sensitivity and specificity of ¹⁸F-choline PET/CT were 81% (95%CI: 78-84%) and 90% (95%CI: 85-93%), respectively. The pooled sensitivity and specificity of ¹¹C-choline PET/CT were 83% (95% CI: 80-86%) and 92% (95% CI: 90-94%), respectively. The pooled detection rate of ¹⁸F-choline PET/CT and ¹¹C-choline PET/CT were 58% (95% CI: 48-68%) and 58% (95%CI: 49-68%), respectively.

Conclusions

Trigger PSA is an important risk factor for positive findings of Choline PET/CT and the detection rate of Choline PET/CT for recurrent prostate cancer increased in parallel with raises in PSA-values. Choline PET/CT got higher detection rate while the trigger PSA > 2ng/ml.

The use of PET/CT in prostate cancer

BACKGROUND

Positron emission tomography/computed tomography (PET/CT) has recently emerged as a promising diagnostic imaging platform for prostate cancer. Several radiolabelled tracers have demonstrated efficacy for cancer detection in various clinical settings. In this review, we aim to illustrate the diverse use of PET/CT with different tracers for the detection of prostate cancer.

METHODS

We searched MEDLINE using the terms 'prostate cancer', 'PET', 'PET/CT' and 'PET/MR'). The current review was limited to ¹⁸F-NaF PET/CT, choline-based PET/CT, fluciclovine PET/CT and PSMA-targeted PET/CT, as these modalities have been the most widely adopted.

RESULTS

NaF PET/CT has shown efficacy in detecting bone metastases with high sensitivity, but relatively low specificity. Currently, choline PET/CT has been the most extensively studied modality. Although having superior specificity, choline PET/CT suffers from low sensitivity, especially at low PSA levels. Nevertheless, choline PET/CT was found to significantly improve upon conventional imaging modalities (CIM) in the detection of metastatic lesions at biochemical recurrence (BCR). Newer methods using fluciclovine and PSMA-targeted radiotracers have preliminarily demonstrated great promise in primary and recurrent staging of prostate cancer. However, their superior efficacy awaits confirmation in larger series.

CONCLUSIONS

PET/CT has emerged as a promising staging modality for both primary and recurrent prostate cancer. Newer tracers have increased detection accuracies for small, incipient metastatic foci. The clinical implications of these occult PET/CT detected disease foci require organized evaluation. Efforts should be aimed at defining their natural history as well as responsiveness and impact of metastasis-directed therapy.

P300 acetyltransferase regulates fatty acid synthase expression, lipid metabolism and prostate cancer growth

De novo fatty acid (FA) synthesis is required for prostate cancer (PCa) survival and progression. As a key enzyme for FA synthesis fatty acid synthase (FASN) is often overexpressed in human prostate cancers and its expression correlates with worse prognosis and poor survival. P300 is an acetyltransferase that acts as a transcription co-activator. Increasing evidence suggests that P300 is a major PCa promoter, although the underlying mechanism remains poorly understood. Here, we demonstrated that P300 binds to and increases histone H3 lysine 27 acetylation (H3K27Ac) in the FASN gene promoter. We provided evidence that P300 transcriptionally upregulates FASN expression and promotes lipid accumulation in human PCa cells in culture and Pten knockout prostate tumors in mice. Pharmacological inhibition of P300 decreased FASN expression and lipid droplet accumulation in PCa cells. Immunohistochemistry analysis revealed that expression of P300 protein positively correlates with FASN protein levels in a cohort of human PCa specimens. We further showed that FASN is a key mediator of P300-induced growth of PCa cells in culture and in mice. Together, our findings demonstrate P300 as a key factor that regulates FASN expression, lipid accumulation and cell growth in PCa. They also suggest that this regulatory pathway can serve as a new therapeutic target for PCa treatment.

Role of PET-CT with 18F-fluorocholine in biochemical recurrence after treatment of prostate cancer with curative intent

OBJECTIVES

To analyse the ability of the PET-CT with ¹⁸F-fluorocholine (¹⁸F-FCH) to detect disease on biochemical recurrence after treatment with curative intent. To determine the clinical variables that would be able to optimise the test's diagnostic yield.

MATERIAL AND METHODS

A retrospective study of PET-CTs with ¹⁸F-fluorocholine performed on 61 patients with prostate cancer who had undergone treatment with curative intent and met the criteria for biochemical recurrence. The results of the PET-CT were categorised into positive or negative and were validated using pre-established criteria. The relationship between the result of the PET-CT and the initial PSA nadir, PSA trigger, rising PSA velocity (PSAva) and PSA doubling time (PSAdt). The relationship between the metastatic sites on the PET-CT and the remaining variables was analysed.

RESULTS

There was a 34.4% detection rate of the disease. The initial PSA, PSA nadir, PSA trigger and PSAva showed statistically significant differences according to the result of the PET-CT. The best discriminatory cut-off point between a positive or negative PET-CT for PSA trigger and PSAva was 3.5ng/ml and 0.25ng/ml/month respectively. The PSAdt was significantly lower in patients with remote disease compared to patients with localised disease (5.1 vs 16.8 months, P=.01). The probability that the PET-CT would detect remote disease vs localised disease was 3.2 times higher if the PSAdt was under 6 months (80% vs 20%, OR: 3.2, P=.02). In the multivariate analysis, only the initial PSA and not having undergone radical prostatectomy were demonstrated as independent predictive factors of a positive PET-CT result.

CONCLUSIONS

The PET-CT with ¹⁸F-FCH can detect disease in a high percentage of patients with biochemical recurrence and provides information on its anatomical location. PSA kinetics and the patient's previous treatment are key variables in increasing the test's diagnostic.

Nanoparticles as Theranostic Vehicles in Experimental and Clinical Applications-Focus on Prostate and Breast Cancer

Prostate and breast cancer are the second most and most commonly diagnosed cancer in men and women worldwide, respectively. The American Cancer Society estimates that during 2016 in the USA around 430,000 individuals were diagnosed with one of these two types of cancers, and approximately 15% of them will die from the disease. In Europe, the rate of incidences and deaths are similar to those in the USA. Several different more or less successful diagnostic and therapeutic approaches have been developed and evaluated in order to tackle this issue and thereby decrease the death rates. By using nanoparticles as vehicles carrying both diagnostic and therapeutic molecular entities, individualized targeted theranostic nanomedicine has emerged as a promising option to increase the sensitivity and the specificity during diagnosis, as well as the likelihood of survival or prolonged survival after therapy. This article presents and discusses important and promising different kinds of nanoparticles, as well as imaging and therapy options, suitable for theranostic applications. The presentation of different nanoparticles and theranostic applications is quite general, but there is a special focus on prostate cancer. Some references and aspects regarding breast cancer are however also presented and discussed. Finally, the prostate cancer case is presented in more detail regarding diagnosis, staging, recurrence, metastases, and treatment options available today, followed by possible ways to move forward applying theranostics for both prostate and breast cancer based on promising experiments performed until today.

PET and PET/CT with radiolabeled choline in prostate cancer: a critical reappraisal of 20 years of clinical studies

We here aim to provide a comprehensive and critical review of the literature concerning the clinical applications of positron emission tomography/computed tomography (PET/CT) with radiolabeled choline in patients with prostate cancer (PCa). We will initially briefly summarize the historical context that brought to the synthesis of [¹¹C]choline, which occurred exactly 20 years ago. We have arbitrarily grouped the clinical studies in three different periods, according to the year in which they were published and according to their relation with their applications in urology, radiotherapy and oncology. Studies at initial staging and, more extensively, studies in patients with biochemical failure, as well as factors predicting positive PET/CT will be reviewed. The capability of PET/CT with radiolabeled choline to provide prognostic information on PCa-specific survival will also be examined. The last sections will be devoted to the use of radiolabeled choline for monitoring the response to androgen deprivation therapy, radiotherapy, and chemotherapy. The accuracy and the limits of the technique will be discussed according to the information available from standard validation processes, including biopsy or histology. The clinical impact of the technique will be discussed on the basis of changes induced in the management of patients and in the evaluation of the response to therapy. Current indications to PET/CT, as officially endorsed by guidelines, or as routinely performed in the clinical practice will be illustrated. Emphasis will be made on methodological factors that might have influenced the results of the studies or their interpretation. Finally, we will briefly highlight the potential role of positron emission tomography/magnetic resonance and of new radiotracers for PCa imaging.

18F-Choline PET/CT scan in staging and biochemical recurrence in prostate cancer patients: Changes in classification and radiotherapy planning

OBJECTIVE

To evaluate the role of the ¹⁸F-Choline PET/CT in prostate cancer management when detecting distant disease in planning radiotherapy and staging and to evaluate the therapy changes guided by PET/TC results.

MATERIAL AND METHODS

A retrospective evaluation was performed on ¹⁸F-Choline PET/CT scans of patients with prostate cancer. Staging and planning radiotherapy scans were selected in patients with at least 9 months follow up. There was a total of 56 studies, 33 (58.93%) for staging, and 23 (41.07%) for planning radiotherapy. All scans were obtained using a hybrid PET/CT scanner. The PET/CT acquisition protocol consisted of a dual-phase procedure after the administration of an intravenous injection of 296-370MBq of ¹⁸F-Choline.

RESULTS

There were 43 out of 56 (76.8%) scans considered as positive, and 13 (23.2%) were negative. The TNM staging was changed in 13 (23.2%) scans. The PET/CT findings ruled out distant disease in 4 out of 13 scans, and unknown distant disease was detected in 9 (69.3%) scans.

CONCLUSIONS

¹⁸F-Choline PET/CT is a useful technique for detecting unknown distant disease in prostate cancer when staging and planning radiotherapy. The inclusion of ¹⁸F-choline PET/CT should be considered in prostate cancer management protocols.

11C-Choline-Avid but 18F-FDG-Nonavid Prostate Cancer with Lymph Node Metastases on Positron Emission Tomography

Choline is a new positron emission tomography (PET) tracer useful for detection of prostate cancer and metastatic lesions. We report a 70-year-old man with prostate cancer and multiple abdominal, pelvic, and inguinal node metastases. PET scans demonstrated accumulation of ¹¹C-choline in the primary tumor and lymph node metastases but no accumulation of ¹⁸F-FDG. Choline PET/computed tomography may be useful for diagnosis of advanced prostate cancer with suspected metastatic lesions and treatment planning.

PET Tracers Beyond FDG in Prostate Cancer

Conventional anatomical imaging with CT and MRI has limitations in the evaluation of prostate cancer. PET is a powerful imaging technique, which can be directed toward molecular targets as diverse as glucose metabolism, density of prostate-specific membrane antigen receptors, and skeletal osteoblastic activity. Although 2-deoxy-2-18F-FDG-PET is the mainstay of molecular imaging, FDG has limitations in typically indolent prostate cancer. Yet, there are many useful and emerging PET tracers beyond FDG, which provide added value. These include radiotracers interrogating prostate cancer via molecular mechanisms related to the biology of choline, acetate, amino acids, bombesin, and dihydrotestosterone, among others. Choline is used for cell membrane synthesis and its metabolism is upregulated in prostate cancer. 11C-choline and 18F-choline are in wide clinical use outside the United States, and they have proven most beneficial for detection of recurrent prostate cancer. 11C-acetate is an indirect biomarker of fatty acid synthesis, which is also upregulated in prostate cancer. Imaging of prostate cancer with 11C-acetate is overall similar to the choline radiotracers yet is not as widely used. Upregulation of amino acid transport in prostate cancer provides the biologic basis for amino acid-based radiotracers. Most recent progress has been made with the nonnatural alicyclic amino acid analogue radiotracer anti-1-amino-3-18F-fluorocyclobutane-1-carboxylic acid (FACBC or fluciclovine) also proven most useful for the detection of recurrent prostate cancer. Other emerging PET radiotracers for prostate cancer include the bombesin group directed to the gastrin-releasing peptide receptor, 16β-18F-fluoro-5α-dihydrotestosterone (FDHT) that binds to the androgen receptor, and those targeting the vasoactive intestinal polypeptide receptor 1 (VPAC-1) and urokinase plasminogen activator receptor (uPAR), which are also overexpressed in prostate cancer.

Radioimmunotherapy for Prostate Cancer--Current Status and Future Possibilities

Prostate cancer (PCa) is one of the most common cancers in men and is the second leading cause of cancer-related deaths in the USA. In the United States, it is the second most frequently diagnosed cancer after skin cancer, and in Europe it is number one. According to the American Cancer Society, approximately 221,000 men in the United States would be diagnosed with PCa during 2015, and approximately 28,000 would die of the disease. According to the International Agency for Research on Cancer, approximately 345,000 men were diagnosed with PCa in Europe during 2012, and despite more emphasis placed on early detection through routine screening, 72,000 men died of the disease. Hence, the need for improved therapy modalities is of utmost importance. And targeted therapies based on radiolabeled specific antibodies or peptides are a very interesting and promising alternative to increase the therapeutic efficacy and overall chance of survival of these patients. There are currently several preclinical and some clinical studies that have been conducted, or are ongoing, to investigate the therapeutic efficacy and toxicity of radioimmunotherapy (RIT) against PCa. One thing that is lacking in a lot of these published studies is the dosimetry data, which are needed to compare results between the studies and the study locations. Given the complicated tumor microenvironment and overall complexity of RIT to PCa, old and new targets and targeting strategies like combination RIT and pretargeting RIT are being improved and assessed along with various therapeutic radionuclides candidates. Given alone or in combination with other therapies, these new and improved strategies and RIT tools further enhance the clinical response to RIT drugs in PCa, making RIT for PCa an increasingly practical clinical tool.

Imaging on nodal staging of prostate cancer

Prostate cancer is the second most common cancer in men and is the second highest cause of cancer death in men of all races. Accurate lymph node staging is essential to ensure adequate treatment of prostate cancer. Historically, conventional imaging methods have demonstrated limited sensitivity and specificity in the detection of lymph node metastases. There are many emerging PET tracers that have recently proven to be effective. In addition, the use of ultrasmall iron oxide nanoparticle-enhanced MRI has demonstrated promising results. This review outlines the strengths and limitations of each of the different imaging modalities as well as individual tracers used, including preclinical and clinical agents.

The ability of 18F-choline PET/CT to identify local recurrence of prostate cancer

PURPOSE

To determine when 18F-choline PET/CT can truly identify local recurrence of prostate cancer.

METHODS

1031 patients from 3 European centers underwent (18)F-choline PET/CT (FCH PET/CT) for recurrent disease; 131 subjects (12.7%) showed a positive FCH uptake in the prostatic gland or prostatic fossa. Median age was 72 years (range 48-87 years), and the median PSA level at the time of FCH PET/CT scan was 4.41 ng/mL (0.22-18.13 ng/mL). 45 patients (34.4%) had a Gleason score (GS) >7, and the residual subjects had a GS ≤ 7. The assessment of true or false-positive FCH PET/CT findings was made by magnetic resonance imaging (n = 34) and/or biopsy in 75/131 cases. A χ (2) test and a Z Kolmogorov-Smirnov test were used to assess the correlation between clinical variables (age, PSA, GS, type of therapy) and FCH PET/CT findings.

RESULTS

FCH PET/CT resulted truly positive (TP) for recurrent disease in the prostatic gland/fossa in 59/75 patients (79%) and falsely positive (FP) in 16 subjects (21%). The median value of PSA at the time of FCH PET/CT scan was higher in TP as compared to FP, although not statistically significant (4.76 vs. 3.04 ng/mL p > 0.05). Similarly, median age, GS categories, and the type of therapy were similar between the two groups (p > 0.05). However, when matching GS categories and PSA values, we found that the number of patients with TP findings were higher in the case of a PSA > 2 ng/mL, independently from the GS (ranging between 74% and 92%). Conversely, FP rate ranged between 50% and 65% in patients with a PSA ≤ 2 ng/mL, especially in the case of GS ≤ 7, whereas FP was around 25% in those with a GS >7 and PSA > 2 ng/mL.

CONCLUSIONS

FCH PET/CT has a limited role in evaluation of prostatic gland/fossa recurrence, due to the physiological biodistribution of the radiopharmaceutical agent. However, in 70-90% of patients with a PSA >2 ng/mL, independently from GS, a focal FCH uptake is compatible with a true local recurrence.

Salvage radiation therapy following radical prostatectomy. A national Danish study

BACKGROUND

The purpose of this observational cohort study was to evaluate the outcome and prognostic factors following salvage radiotherapy (SRT) in a consecutive national cohort.

MATERIAL AND METHODS

Between 2006 and 2010, 259 patients received SRT in Denmark. Patient- and cancer-related characteristics were retrospectively retrieved from patient charts. The primary end point was biochemical progression-free survival (b-PFS).

RESULTS

At the end of follow-up, 51% of the patients displayed a prostate-specific antigen (PSA) level <0.1 ng/ml. The three-year b-PFS rate for the total cohort was 57.0%. Nearly half of the patients (44%) received androgen deprivation therapy (ADT) in combination with SRT. Positive surgical tumour margins (p = 0.025) and ADT (p = 0.001) were the only markers independently correlated with b-PFS. In patients who received SRT without ADT, both a pre-SRT PSA level ≤0.5 ng/ml (p = 0.003) and pathological tumour stage T1-T2 (p = 0.036) independently correlated with b-PFS. Moreover, a duration between radical prostatectomy (RP) and SRT ≤29 months (p = 0.035) independently correlated with b-PFS in patients treated with ADT in combination with RT.

CONCLUSIONS

In patients treated for biochemical failure after RP, positive surgical tumour margins and PSA levels ≤0.5 ng/mL at the time of SRT were associated with a favourable outcome. Despite less favourable tumour characteristics, patients receiving SRT and ADT demonstrated improved b-PFS, and in particular, patients with PSA levels >0.2 ng/ml benefitted from additional ADT.

Initial Evaluation of [(18)F]DCFPyL for Prostate-Specific Membrane Antigen (PSMA)-Targeted PET Imaging of Prostate Cancer

PURPOSE

Prostate-specific membrane antigen (PSMA) is a recognized target for imaging prostate cancer. Here we present initial safety, biodistribution, and radiation dosimetry results with [(18)F]DCFPyL, a second-generation fluorine-18-labeled small-molecule PSMA inhibitor, in patients with prostate cancer.

PROCEDURES

Biodistribution was evaluated using sequential positron-emission tomography (PET) scans in nine patients with prostate cancer. Time-activity curves from the most avid tumor foci were determined. The radiation dose to selected organs was estimated using OLINDA/EXM.

RESULTS

No major radiotracer-specific adverse events were observed. Physiologic accumulation was observed in known sites of PSMA expression. Accumulation in putative sites of prostate cancer was observed (SUVmax up to >100, and tumor-to-blood ratios up to >50). The effective radiation dose from [(18)F]DCFPyL was 0.0139 mGy/MBq or 5 mGy (0.5 rem) from an injected dose of 370 MBq (10 mCi).

CONCLUSIONS

[(18)F]DCFPyL is safe with biodistribution as expected, and its accumulation is high in presumed primary and metastatic foci. The radiation dose from [(18)F]DCFPyL is similar to that from other PET radiotracers.

Optimized protocol for (18)F-choline PET/CT in patients with biochemically relapsed prostate cancer: experiences on 250 consecutive cases

PURPOSE

We review acquisition F-choline PET/CT methodology, evaluate a new F-choline acquisition protocol for prostate cancer (PC), and propose a standardized acquisition protocol on F-choline in PC patients.

MATERIALS

Two hundred fifty consecutive PC patients (mean age 72 years, mean PSA 7.9 ng/mL) were prospectively evaluated with F-choline PET/CT. An early scan of the pelvis (1 bed position of 4 minutes) was followed by a whole-body scan at 1 hour. Early and 1 delayed hour images of the pelvis were compared.

RESULTS

Twenty-one percent of patients (n = 57) with positive F-choline demonstrated abnormal local uptake; 18% of patients (n = 45) showed distant localization only; 23% of patients (n = 53) had both local and distant localization; 38% of patients (n = 38) did not show any pathological uptake. All early images showed absence of radioactive urine in ureters, bladder, or urethra with satisfactory visualization of the prostatic region. Considering the group of patients with local uptake only, the prostatic region uptake, confirmed by late images, was better visualized in the early phase in 32/57 cases (SUVmax 12.4 ± 3.2 vs. 7.3 ± 5.2, P <0.01). Instead distant lesions were visualized on both early and late images with similar uptakes values (SUVmax 9.8 ± 4.1 vs. 10.3 ± 4.5, P = N.S.).

CONCLUSION

Early F-choline images improve pelvic prostate cancer lesion clarity. All pathologic pelvic deposits (prostate, lymph nodes, bone) were visualized both in the early and late images.

Molecular Imaging of Prostate Cancer

Prostate cancer is the most common noncutaneous malignancy among men in the Western world. The natural history and clinical course of prostate cancer are markedly diverse, ranging from small indolent intraprostatic lesions to highly aggressive disseminated disease. An understanding of this biologic heterogeneity is considered a necessary requisite in the quest for the adoption of precise and personalized management strategies. Molecular imaging offers the potential for noninvasive assessment of the biologic interactions underpinning prostate carcinogenesis. Currently, numerous molecular imaging probes are in clinical use or undergoing preclinical or clinical evaluation. These probes can be divided into those that image increased cell metabolism, those that target prostate cancer-specific membrane proteins and receptor molecules, and those that bind to the bone matrix adjacent to metastases to bone. The increased metabolism and vascular changes in prostate cancer cells can be evaluated with radiolabeled analogs of choline, acetate, glucose, amino acids, and nucleotides. The androgen receptor, prostate-specific membrane antigen, and gastrin-releasing peptide receptor (ie, bombesin) are overexpressed in prostate cancer and can be targeted by specific radiolabeled imaging probes. Because metastatic prostate cancer cells induce osteoblastic signaling pathways of adjacent bone tissue, bone-seeking radiotracers are sensitive tools for the detection of metastases to bone. Knowledge about the underlying biologic processes responsible for the phenotypes associated with the different stages of prostate cancer allows an appropriate choice of methods and helps avoid pitfalls.

PET/CT with (11)C-choline for evaluation of prostate cancer patients with biochemical recurrence: meta-analysis and critical review of available data

PURPOSE

For the last decade PET and PET/CT with (11)C-choline have been proposed for the evaluation of prostate cancer (PC), but the diagnostic performance of (11)C-choline PET/CT is still a matter of debate. We performed a comprehensive review of the most important clinical application of (11)C-choline PET, restaging of patients with biochemical relapse, following a rigorous methodological approach and including assessment of the risk of bias. We conducted a systematic review and meta-analysis of the literature assessing (11)C-choline PET/CT for its accuracy in the diagnosis and ability to detect the site of recurrence of PC in the restaging of patients with biochemical recurrence after initial treatment with curative intent.

METHODS

We performed a comprehensive literature search of PubMed and the Cochrane Library to determine the accuracy for the detection of the site of recurrence (prostate bed recurrences, metastatic spread to locoregional pelvic lymph nodes or distant metastases). Only studies with a reference standard (for prostatic bed histopathology, for histopathology or biopsy of distant metastases or a composite reference standard with clinical follow-up of at least 12 months, correlative imaging and clinical data) were included.

RESULTS

Overall 425 studies were retrieved, of which 43 were judged as potentially relevant and 29 with 2,686 participants were finally included. Of these 29 studies, 18 reported results for any relapse, All 18 studies, with a total of 2,126 participants, reported detection rates. The pooled rate was 62 % (95 % CI 53 - 71 %). Of the 18 studies, 12 with 1,270 participants reported useful data to derive sensitivity and specificity. The pooled sensitivity was 89 % (95 % CI 83 - 93 %) and the pooled specificity was 89 % (95 % CI 73 - 96 %). Of 11 studies reporting results for local relapse, 9 with 993 participants reported detection rates. The pooled rate was 27 % (95 % CI 16 - 38 %). Six studies with 491 participants reported sensitivity and specificity. The pooled sensitivity was 61 % (95 % CI 40 - 80 %) and the pooled specificity was 97 % (95 % CI 87 - 99 %). Ten studies reported results for lymph nodes and distant metastases. For nodal disease, 7 studies with 752 participants reported detection rates. The pooled rate was 36 % (95 % CI 22 - 50 %). For bone metastases, 8 studies with 775 participants reported detection rates. The pooled rate was 25 % (95 % CI 16 - 34 %).

CONCLUSION

There is a significant amount of (11)C-choline PET data published showing a high degree of consistency in inclusion criteria, acquisition protocols and scan interpretation criteria. Furthermore, the quality of the data derived limited to the same standard of reference was acceptable. Despite a high variability in the observed prevalence of any relapse, the diagnostic performance of (11)C-choline PET was in line with previous meta-analyses. Our data confirm the very good accuracy of (11)C-choline PET for detection of lymph node metastases and/or distant lesions in a single examination in patients with biochemical relapse.

Significance of 18F-fluorocholine PET/CT positive pulmonary lesions in prostate cancer patients

AIM

To assess the frequency and the significance of incidental pulmonary lesions with 18F-fluorocholine (18F-FCH) PET/CT in prostate cancer (PCa) patients.

PATIENTS, METHODS

225 consecutive PCa patients referred for 18F-FCH PET/CT (median age 68 years) were retrospectively evaluated for the presence of lesions in the lungs: 173 referred for restaging and 52 for initial staging regarding their high risk of extra prostatic extension. The final diagnosis was based on histopathological or on clinical and radiological follow-up.

RESULTS

13 patients had 18F-FCH positive pulmonary and 8 patients malignant lesions: 5 patients (38%) had a primary lung cancer (2 squamous cell carcinomas, 1 papillary adenocarcinoma, 1 typical pulmonary carcinoid, 1 bronchioloalveolar carcinoma) and 3 patients (23%) PCa metastases. Benign lesions were found in 5 subjects (38%). SUVmax and maximum diameter were neither significantly different in primary and metastatic tumors nor between malignant and benign lesions.

CONCLUSIONS

Although our results suggest that incidental uptake in the lungs in PCa patients are nonspecific, their detection may have a significant impact on patient management knowing that more than 60% represent malignant disease.