Positron emission tomography with 11C-acetate and 18F-FDG in prostate cancer patients

Recent advancement of imaging strategies of the lymphatic system: Answer to the decades old questions

The role of the lymphatic system in maintaining tissue homeostasis and a number of different pathophysiological conditions has been well established. The complex and delicate structure of the lymphatics along with the limitations of conventional imaging techniques make lymphatic imaging particularly difficult. Thus, in-depth high-resolution imaging of lymphatic system is key to understanding the progression of lymphatic diseases and cancer metastases and would greatly benefit clinical decisions. In recent years, the advancement of imaging technologies and development of new tracers suitable for clinical applications has enabled imaging of the lymphatic system in both clinical and pre-clinical settings. In this current review, we have highlighted the advantages and disadvantages of different modern techniques such as near infra-red spectroscopy (NIRS), positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI) and fluorescence optical imaging, that has significantly impacted research in this field and has led to in-depth insights into progression of pathological states. This review also highlights the use of current imaging technologies, and tracers specific for immune cell markers to identify and track the immune cells in the lymphatic system that would help understand disease progression and remission in immune therapy regimen.

Synthesis and Evaluation of 11C-Labeled Triazolones as Probes for Imaging Fatty Acid Synthase Expression by Positron Emission Tomography

Cancer cells require lipids to fulfill energetic, proliferative, and signaling requirements. Even though these cells can take up exogenous fatty acids, the majority exhibit a dependency on de novo fatty acid synthesis. Fatty acid synthase (FASN) is the rate-limiting enzyme in this process. Expression and activity of FASN is elevated in multiple cancers, where it correlates with disease progression and poor prognosis. These observations have sparked interest in developing methods of detecting FASN expression in vivo. One promising approach is the imaging of radiolabeled molecular probes targeting FASN by positron emission tomography (PET). However, although [11C]acetate uptake by prostate cancer cells correlates with FASN expression, no FASN-specific PET probes currently exist. Our aim was to synthesize and evaluate a series of small molecule triazolones based on GSK2194069, an FASN inhibitor with IC50 = 7.7 ± 4.1 nM, for PET imaging of FASN expression. These triazolones were labeled with carbon-11 in good yield and excellent radiochemical purity, and binding to FASN-positive LNCaP cells was significantly higher than FASN-negative PC3 cells. Despite these promising characteristics, however, these molecules exhibited poor in vivo pharmacokinetics and were predominantly retained in lymph nodes and the hepatobiliary system. Future studies will seek to identify structural modifications that improve tumor targeting while maintaining the excretion profile of these first-generation 11C-methyltriazolones.

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.

Prediction of prostate cancer aggressiveness using 18F-Fluciclovine (FACBC) PET and multisequence multiparametric MRI

The aim of this prospective single-institution clinical trial (NCT02002455) was to evaluate the potential of advanced post-processing methods for 18F-Fluciclovine PET and multisequence multiparametric MRI in the prediction of prostate cancer (PCa) aggressiveness, defined by Gleason Grade Group (GGG). 21 patients with PCa underwent PET/CT, PET/MRI and MRI before prostatectomy. DWI was post-processed using kurtosis (ADCk, K), mono- (ADCm), and biexponential functions (f, Dp, Df) while Logan plots were used to calculate volume of distribution (VT). In total, 16 unique PET (VT, SUV) and MRI derived quantitative parameters were evaluated. Univariate and multivariate analysis were carried out to estimate the potential of the quantitative parameters and their combinations to predict GGG 1 vs >1, using logistic regression with a nested leave-pair out cross validation (LPOCV) scheme and recursive feature elimination technique applied for feature selection. The second order rotating frame imaging (RAFF), monoexponential and kurtosis derived parameters had LPOCV AUC in the range of 0.72 to 0.92 while the corresponding value for VT was 0.85. The best performance for GGG prediction was achieved by K parameter of kurtosis function followed by quantitative parameters based on DWI, RAFF and 18F-FACBC PET. No major improvement was achieved using parameter combinations with or without feature selection. Addition of 18F-FACBC PET derived parameters (VT, SUV) to DWI and RAFF derived parameters did not improve LPOCV AUC.

Comparison of FDG-PET/CT for Cancer Detection in Populations With Different Risks of Underlying Malignancy

Background/Aim: Whole-body positron-emission tomography/computed tomography with the glucose analog 2-[ 18 F]fluoro-2-deoxy-D-glucose (FDG-PET/CT) has been used to screen examinees for underlying malignancy in many countries. The aim of this study was to compare the potential value of FDG-PET/CT application in asymptomatic individuals with those with suspected malignancy. Patients and Methods: A total of 9,408 examinees underwent whole-body FDG-PET/CT at our hospital from July 2006 to August 2013. Three thousand and seven hundred asymptomatic individuals and 848 individuals with laboratory and clinical/radiologicaI suspicion of malignancy who had undergone FDG-PET/CT for cancer screening were recruited. The final confirmation of cancer and outcomes were based on a pathological report and continuous follow-up. Results: Forty-five out of 3,700 asymptomatic individuals (1.2%) had proven malignancy, and 42 of them (93.3%) were found by FDG-PET/CT. Two hundred and twelve out of 848 with suspected malignancy (25%) had proven malignancy, and 196 of them (92.5%) were detected by FDG-PET/CT. Most of these cancers in asymptomatic individuals were clinically at an early stage. The discovery rate in asymptomatic individuals and those with suspected malignancy was 1.1% and 23.1%, respectively. The overall survival of patients with cancer diagnosed with PET/CT was higher than those with suspected malignancy (78.6% vs. 48.5%, p<0.001). Patients with a resectable lesion, early-stage disease, and lower maximal standardized uptake value had significantly better survival than those without. Conclusion: FDG-PET/CT is useful in the early diagnosis of cancer and thus might improve the survival rates of these patients. Considering the costs and risk of radiation exposure, it would be better used as a priority in patients with laboratory and clinical/radiologic suspicion of malignancy.

Evaluation of Prostate Cancer with 11C-Acetate PET/CT

In this article, we will first describe the metabolic fate of ¹¹C-acetate; then discuss its biodistribution in health and disease; and subsequently focus on its key clinical applications, the detection and localization of prostate cancer tissue in patients with primary or recurrent disease. Finally, we will discuss the potential role of ¹¹C-acetate in the context of other prostate cancer imaging probes and non-radionuclide-based imaging approaches.

Malignant lipogenesis defined by 11C-acetate PET/CT predicts prostate cancer-specific survival in patients with biochemical relapse after prostatectomy

PURPOSE

Malignant de novo lipogenesis is strongly linked to the aggressiveness of prostate cancer (PCa) under experimental conditions. ¹¹C-Acetate PET/CT is a potential noninvasive biomarker of malignant lipogenesis in PCa, but its prognostic value is not known. The objective of this study was to analyse ¹¹C-acetate PET/CT image metrics in relation to survival.

METHODS

All patients undergoing ¹¹C-acetate PET/CT in one university hospital from 2005 to 2011 due to PSA relapse after previous prostatectomy were retrospectively evaluated. Two groups of patients were compared: those who died from PCa and those who were censored. All previously reported findings of local recurrence, regional or distal lymph node metastases and bone metastases were counted and evaluated regarding ¹¹C-acetate uptake intensity (SUV_max) and tumour volume. Total tumour volume and total lipogenic activity (TLA, summed SUV_max × TV) were calculated. Survival analysis in the entire study population was followed by Cox proportional hazards ratio (HR) analysis.

RESULTS

A total of 121 patients were included, and 22 PCa-specific deaths were recorded. The mean PSA level at the time of PET was 2.69 ± 4.35 ng/mL. The median follow-up of the study population was 79 ± 28 months. PET identified at least one PCa lesion in 53 % of patients. Five-year PCa-specific survival after PET was 80 % and 100 % in patients with a positive and a negative PET scan, respectively (p < 0.001). Time-to-death was linearly correlated with highest SUV_max (r = -0.55, p = 0.01) and nonlinearly with TLA (r = -0.75, p < 0.001). Multivariate analysis showed statistical significance for number of bone metastases (HR 1.74, p = 0.01), tertile of TLA (HR 5.63, p = 0.029) and postoperative Gleason score (HR 1.84, p = 0.045).

CONCLUSION

Malignant ¹¹C-acetate accumulation measured with PET/CT is a strong predictor of survival in the setting of PSA relapse after prostatectomy. The study provides further evidence for a quantitative relationship between malignant de novo lipogenesis and early death. ¹¹C-Acetate PET/CT might be useful for identifying a high-risk population of relapsing patients in which therapies targeting malignant lipogenesis might be of particular benefit.

Molecular and Functional Imaging of Bone Metastases in Breast and Prostate Cancers: An Overview

Our ability to accurately assess the skeleton for metastases in breast and prostate cancers has improved significantly in recent years with hybrid imaging methods. Nevertheless, no consensus has been reached on the best imaging modality for diagnosis and treatment response assessment of skeletal disease. Hybrid SPECT/CT has low false-positive and false-negative rates compared with planar bone scintigraphy (BS) or BS augmented with SPECT in breast and prostate cancers. In breast cancer, 18F-FDG PET is more sensitive and accurate at detecting bone metastases than BS. Currently, little evidence has accrued to support the superiority of 18F-fluoride (18F-NaF) PET in diagnosing osseous metastases or monitoring treatment response in breast cancer when compared with conventional imaging. In prostate cancer, the sensitivities of 18F-NaF PET/CT, 18F-fluorocholine (18F-choline), or 11C-choline PET/CT are equivalent, although 11C-/18F-choline PET/CT scans are more specific. Whole-body MRI, using anatomical sequences complemented by diffusion-weighted MRI, shows early evidence of utility for diagnosis and monitoring therapy response. We review the literature for staging and response assessment in metastatic breast and prostate cancer. While staging accuracy has significantly improved with hybrid imaging, optimal methods for assessing early treatment response have not been determined, and this is an area of active research.

Intraoperative mapping of sentinel lymph node metastases using a clinically translated ultrasmall silica nanoparticle

The management of regional lymph nodes in patients with melanoma has undergone a significant paradigm shift over the past several decades, transitioning from the use of more aggressive surgical approaches, such as lymph node basin dissection, to the application of minimally invasive sentinel lymph node (SLN) biopsy methods to detect the presence of nodal micrometastases. SLN biopsy has enabled reliable, highly accurate, and low-morbidity staging of regional lymph nodes in early stage melanoma as a means of guiding treatment decisions and improving patient outcomes. The accurate identification and staging of lymph nodes is an important prognostic factor, identifying those patients for whom the expected benefits of nodal resection outweigh attendant surgical risks. However, currently used standard-of-care technologies for SLN detection are associated with significant limitations. This has fueled the development of clinically promising platforms that can serve as intraoperative visualization tools to aid accurate and specific determination of tumor-bearing lymph nodes, map cancer-promoting biological properties at the cellular/molecular levels, and delineate nodes from adjacent critical structures. Among a number of promising cancer-imaging probes that might facilitate achievement of these ends is a first-in-kind ultrasmall tumor-targeting inorganic (silica) nanoparticle, designed to overcome translational challenges. The rationale driving these considerations and the application of this platform as an intraoperative treatment tool for guiding resection of cancerous lymph nodes is discussed and presented within the context of alternative imaging technologies. WIREs Nanomed Nanobiotechnol 2016, 8:535-553. doi: 10.1002/wnan.1380 For further resources related to this article, please visit the WIREs website.

Imaging and evaluation of patients with high-risk prostate cancer

Approximately 15% of men with newly diagnosed prostate cancer have high-risk disease. Imaging is critically important for the diagnosis and staging of these patients, and also for the selection of management. While established prostate cancer staging guidelines have increased the appropriate use of imaging, underuse for high-risk prostate cancer remains substantial. Several factors affect the utility of initial diagnostic imaging, including the variable definition of high-risk prostate cancer, variable guideline recommendations, poor accuracy of existing imaging tests, and the difficulty in validating imaging findings. Conventional imaging modalities, including CT and radionuclide bone scan, have been employed for local and metastatic staging, but their performance characteristics have generally been poor. Emerging modalities including multiparametricMRI, positron emission tomography (PET)-CT, and PET-MRI have shown increased diagnostic accuracy and could improve accuracy in staging patients with high-risk prostate cancer.

Comparison of meta-analyses among elastosonography (ES) and positron emission tomography/computed tomography (PET/CT) imaging techniques in the application of prostate cancer diagnosis

The early diagnosis of prostate cancer (PCa) appears to be of vital significance for the provision of appropriate treatment programs. Even though several sophisticated imaging techniques such as positron emission tomography/computed tomography (PET/CT) and elastosonography (ES) have already been developed for PCa diagnosis, the diagnostic accuracy of these imaging techniques is still controversial to some extent. Therefore, a comprehensive meta-analysis in this study was performed to compare the accuracy of various diagnostic imaging methods for PCa, including 11C-choline PET/CT, 11C-acetate PET/CT, 18F-fluorocholine PET/CT, 18F-fluoroglucose PET/CT, transrectal real-time elastosonography (TRTE), and shear-wave elastosonography (SWE). The eligible studies were identified through systematical searching for the literature in electronic databases including PubMed, Cochrane, and Web of Science. On the basis of the fixed-effects model, the pooled sensitivity (SEN), specificity (SPE), and area under the receiver operating characteristics curve (AUC) were calculated to estimate the diagnostic accuracy of 11C-choline PET/CT, 11C-acetate PET/CT, 18F-fluorocholine (FCH) PET/CT, 18F-fluoroglucose (FDG) PET/CT, TRTE, and SWE. All the statistical analyses were conducted with R language Software. The present meta-analysis incorporating a total of 82 studies demonstrated that the pooled sensitivity of the six imaging techniques were sorted as follows: SWE > 18F-FCH PET/CT > 11C-choline PET/CT > TRTE > 11C-acetate PET/CT > 18F-FDG PET/CT; the pooled specificity were also compared: SWE > 18F-FCH PET/CT > 11C-choline PET/CT > TRTE > 18F-FDG PET/CT > 11C-acetate PET/CT; finally, the pooled diagnostic accuracy of the six imaging techniques based on AUC were ranked as below: SWE > 18F-FCH PET/CT > 11C-choline PET/CT > TRTE > 11C-acetate PET/CT > 18F-FDG PET/CT. SWE and 18F-FCH PET/CT imaging could offer more assistance in the early diagnosis of PCa than any other studied imaging techniques. However, the diagnostic ranking of the six imaging techniques might not be applicable to the clinical phase due to the shortage of stratified analysis.

Lymph node staging in prostate cancer

Nodal staging is important in prostate cancer treatment. While surgical lymph node dissection is the classic method of determining whether lymph nodes harbor malignancy, this is a very invasive technique. Current noninvasive approaches to identifying malignant lymph nodes are limited. Conventional imaging methods rely on size and morphology of lymph nodes and have notoriously low sensitivity for detecting malignant nodes. New imaging techniques such as targeted positron emission tomography (PET) imaging and magnetic resonance lymphography (MRL) with iron oxide particles are promising for nodal staging of prostate cancer. In this review, the strengths and limitations of imaging techniques for lymph node staging of prostate cancer are discussed.

Lymphatic imaging: focus on imaging probes

In view of the importance of sentinel lymph nodes (SLNs) in tumor staging and patient management, sensitive and accurate imaging of SLNs has been intensively explored. Along with the advance of the imaging technology, various contrast agents have been developed for lymphatic imaging. In this review, the lymph node imaging agents were summarized into three groups: tumor targeting agents, lymphatic targeting agents and lymphatic mapping agents. Tumor targeting agents are used to detect metastatic tumor tissue within LNs, lymphatic targeting agents aim to visualize lymphatic vessels and lymphangionesis, while lymphatic mapping agents are mainly for SLN detection during surgery after local administration. Coupled with various signal emitters, these imaging agents work with single or multiple imaging modalities to provide a valuable way to evaluate the location and metastatic status of SLNs.

Imaging biomarkers in prostate cancer: role of PET/CT and MRI

Prostate-specific antigen (PSA) is currently the most widely used biomarker of prostate cancer (PCa). PSA suggests the presence of primary tumour and disease relapse after treatment, but it is not able to provide a clear distinction between locoregional and distant disease. Molecular and functional imaging, that are able to provide a detailed and comprehensive overview of PCa extension, are more reliable tools for primary tumour detection and disease extension assessment both in staging and restaging. In the present review we evaluate the role of PET/CT and MRI in the diagnosis, staging and restaging of PCa, and the use of these imaging modalities in prognosis, treatment planning and response assessment. Innovative imaging strategies including new radiotracers and hybrid scanners such as PET/MRI are also discussed.

[Diagnostic performance of bone scintigraphy and (11)C-Choline PET/CT in the detection of bone metastases in patients with biochemical recurrence of prostate cancer]

AIM

To compare bone scan (BS) with (11)C-Choline PET/CT for the detection of bone metastases in patients with biochemical recurrence of prostate cancer (PC).

MATERIAL AND METHODS

A total of 169 patients with biochemical recurrence of PC(PSA:2.4-58 ng/ml) who were referred for both exams (0-15 days-in-between) were included. Lesion-detection-rate per patients and lesions were analyzed for both BS and (11)C-Choline PET/CT. Metastasis diagnosis was reached by: biopsy, CT/(18)F-Fluoride PET/MRI confirmation, or evidence of progression in subsequent imaging procedures.

RESULTS

A total of 91 lesions were found to be active in BS and/or (11)C-choline PET/CT (40 patients), with 78 of which were metastatic. BS detected 38 blastic, 2 lytic and 10 non-CT-evident lesions. (11)C-Choline PET/CT detected 41 blastic, 4 lytic and 29 non-CT-evident lesions. BS and (11)C-Choline PET/CT sensitivities were 65.4% and 96.1%; specificities ere 38.5 and 92.3% (χ(2) 8.27, p<0.04). Both imaging techniques were negative in 118 patients. Tracer avid lesions were found in 51 patients: with 30/51 being BS and (11)C-Choline PET/CT concordant; in 21/51 patients had discordant lesions (kappa 0.712, p=0.00). Lesions were absolutely discordant in 10/19 patients,: 5 FN BS, 2 FP BS (degenerative changes; dysplasia), 1 FN (11)C-Choline PET/CT (blastic), 1 FP (11)C-Choline PET/CT (degenerative), 1 out of field-of-view lesion with (11)C-Choline PET/CT (tibia alone). (11)C-Choline PET/CT showed extraosseous involvement in 26/51 patients with bone metastases: 9 local recurrences, 5 infra-diaphragmatic-lymph-nodes, 2 supra-diaphragmatic, 5 local and infra-diaphragmatic, 4 infra- and supra-diaphragmatic, 1 supra-diaphragmatic and lung metastases.

CONCLUSION

(11)C-Choline PET/CT yielded better sensitivity and specificity than BS for the detection of bone involvement in patients with biochemical recurrence of PC and allowed extraosseous restaging, with an impact in the clinical management of these patients.

Diagnosis of complex renal cystic masses and solid renal lesions using PET imaging: comparison of 11C-acetate and 18F-FDG PET imaging

PURPOSE

The study aims to assess the usefulness of PET with C-acetate and F-FDG to differentiate renal cell carcinoma (RCC) from complicated renal cysts.

METHODS

Thirty-one patients were enrolled, 14 patients with complicated renal cysts (12 with Bosniak III and 2 with Bosniak IV) and 17 patients with 19 solid renal tumors. The patients underwent both C-acetate PET and FDG PET. Nephrectomy or partial nephrectomy was performed after the PET scans.

RESULTS

In 29 patients, 32 renal lesions were diagnosed as RCC. Twenty-three of the 32 RCCs (72%) had positive C-acetate PET findings, whereas only 7 FDG PET studies were positive (22%). Considering the relationship between tumor size measured by macroscopic appearance of resected tumors and PET results, 22 of 25 (88%) tumors more than 1.5 cm showed positive C-acetate PET findings. In 12 patients with Bosniak III renal cysts, 10 renal lesions were diagnosed as RCC. In this subgroup, 5 of the 10 RCCs (50%) had positive C-acetate PET findings, whereas 2 RCCs (20%) had positive FDG PET findings. None of the cases with benign findings had positive C-acetate PET or FDG PET scans.

CONCLUSIONS

C-acetate PET demonstrates a pronounced increase in tracer uptake in RCC, especially in renal tumors more than 1.5 cm, and displays a higher sensitivity than FDG PET. These preliminary data show that C-acetate may be a useful PET tracer to exclude RCC in complex renal cysts.

Advanced imaging for the early diagnosis of local recurrence prostate cancer after radical prostatectomy

Currently the diagnosis of local recurrence of prostate cancer (PCa) after radical prostatectomy (RT) is based on the onset of biochemical failure which is defined by two consecutive values of prostate-specific antigen (PSA) higher than 0.2 ng/mL. The aim of this paper was to review the current roles of advanced imaging in the detection of locoregional recurrence. A nonsystematic literature search using the Medline and Cochrane Library databases was performed up to November 2013. Bibliographies of retrieved and review articles were also examined. Only those articles reporting complete data with clinical relevance for the present review were selected. This review article is divided into two major parts: the first one considers the role of PET/CT in the restaging of PCa after RP; the second part is intended to provide the impact of multiparametric-MRI (mp-MRI) in the depiction of locoregional recurrence. Published data indicate an emerging role for mp-MRI in the depiction of locoregional recurrence, while the performance of PET/CT still remains unclear. Moreover Mp-MRI, thanks to functional techniques, allows to distinguish between residual glandular healthy tissue, scar/fibrotic tissue, granulation tissue, and tumour recurrence and it may also be able to assess the aggressiveness of nodule recurrence.

A paradigm shift from anatomic to functional and molecular imaging in the detection of recurrent prostate cancer

Approximately a third of men with localized prostate cancer who are treated with external beam radiation therapy (EBRT) or radical prostatectomy (RP) develop biochemical failure (BF). Presumably, BF will progress to distant metastasis and prostate cancer-specific mortality in some patients over subsequent years. Accurate detection of recurrent disease is important because it allows for appropriate treatment selection (e.g., local vs systemic therapy) and early delivery of therapy (e.g., salvage EBRT), which affect patient outcome. In this article, we discuss the paradigm shift in imaging technology in the detection of recurrent prostate cancer. First, we discuss the commonly used morphological and anatomical imaging modalities and their role in the post-RP and post-EBRT settings of BF. Second, we discuss the accuracy of functional and molecular imaging techniques, many of which are under investigation. Further studies are needed to establish the role of imaging techniques for detection of cancer recurrence and clinical decision-making.

Imaging of prostate carcinoma

BACKGROUND

Imaging of prostate carcinoma is an important adjunct to clinical evaluation and prostate specific antigen measurement for detecting metastases and tumor recurrence. In the past, the ability to assess intraprostatic tumor was limited.

METHODS

Pertinent literature was reviewed to describe the capabilities and limitations of the currently available imaging techniques for assessing prostate carcinoma. Evaluation of primary tumor and metastatic disease by ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine techniques is discussed.

RESULTS

Ultrasonography and MRI have limited usefulness for local staging of prostate cancer because of suboptimal sensitivity and specificity for identifying tumor extent and capsular penetration. Additional MRI techniques such as magnetic resonance-based perfusion imaging, diffusion imaging, and spectroscopy may provide incremental benefit. CT and bone scanning provide an assessment of metastatic disease but are also limited by the poor sensitivity of lymph node size as a criterion for detecting metastases. Novel imaging techniques such as hybrid imaging devices in the form of single-photon emission CT/CT gamma cameras, positron emission tomography/CT cameras, and, in the near future, positron emission tomography/MRI combined with tumor specific imaging radiotracers may have a significant impact on tumor staging and treatment response.

CONCLUSIONS

Cross-sectional imaging and scintigraphy have an important role in assessing prostate carcinoma metastases and treatment response. Increasingly, the incremental value of primary tumor imaging through MRI is being realized.

Contemporary issues in radiotherapy for clinically localized prostate cancer

Radiotherapy is a valid curative alternative to surgery for prostate cancer. However, patient selection is critical to ensure patients obtain benefits from therapy delivered with curative intent. Dose-escalated radiation has been shown to improve patient outcomes, facilitated by development of robust image guidance and better target delineation imaging technologies. These concepts have also rekindled interest in hypofractionated radiotherapy in the forms of stereotactic body radiotherapy and brachytherapy. Postprostatectomy radiotherapy also improves long-term biochemical outcome in men at high risk of local recurrence.

The potential of ¹¹C-acetate PET for monitoring the Fatty acid synthesis pathway in Tumors

Positron emission tomography (PET) is a molecular imaging modality that provides the opportunity to rapidly and non-invasively visualize tumors derived from multiple organs. In order to do so, PET utilizes radiotracers, such as ¹⁸F-FDG and ¹¹C-acetate, whose uptake coincides with altered metabolic pathways within tumors. Increased expression and activity of enzymes in the fatty acid synthesis pathway is a frequent hallmark of cancer cells. As a result, this pathway has become a prime target for therapeutic intervention. Although multiple drugs have been developed that both directly and indirectly interfere with fatty acid synthesis, an optimal means to assess their efficacy is lacking. Given that ¹¹Cacetate is directly linked to the fatty acid synthesis pathway, this probe provides a unique opportunity to monitor lipogenic tumors by PET. Herein, we review the relevance of the fatty acid synthesis pathway in cancer. Furthermore, we address the potential utility of ¹¹C-acetate PET in imaging tumors, especially those that are not FDG-avid. Last, we discuss several therapeutic interventions that could benefit from ¹¹C-acetate PET to monitor therapeutic response in patients with certain types of cancers.

Imaging of castration-resistant prostrate cancer: development of imaging response biomarkers

PURPOSE OF REVIEW

The current standard for imaging castration-resistant prostate cancer (CRPC) focuses solely on detection. However, in order to assess treatment response, imaging must provide quantitative results that can be validated.

RECENT FINDINGS

Bone scintigraphy remains the most commonly used imaging tool for CRPC in bone, but with limited quantification capabilities. Both PET and MRI provide quantitative measures that could be used to assess treatment response. Several PET tracers have been shown to be able to detect bone metastases, but more research regarding their use for treatment response assessment is necessary. Similarly, research has shown that diffusion-weighted and dynamic contrast-enhanced MRI can detect metastases, with some studies suggesting that they may be suitable for assessing treatment response.

SUMMARY

Recent research has shown that many imaging techniques are able to successfully detect metastases in CRPC patients as well as or better than standard imaging. These imaging methods can also be applied to treatment response assessment; however, more research must be done to validate the quantitative measures before these techniques can be used clinically for assessing patients.

Update on positron emission tomography for imaging of prostate cancer

Prostate cancer is the most common non-cutaneous malignancy among men in the Western world, and continues to be a major health problem. Imaging has recently become more important in the clinical management of prostate cancer patients, including diagnosis, staging, choice of optimal treatment strategy, treatment follow up and restaging. Positron emission tomography, a functional and molecular imaging technique, has opened a new field in clinical oncological imaging. The most common positron emission tomography radiotracer, 18F-fluorodeoxyglucose, has been limited in imaging of prostate cancer. Recently, however, other positron emission tomography tracers, such as 11C-acetate and 11C- or (18) F-choline, have shown promising results. In the present review article, we overview the potential and current use of positron emission tomography or positron emission tomography/computed tomography imaging employing the four most commonly used positron emission tomography radiotracers, 18F-fluorodeoxyglucose, 11C-acetate and 11C- or 18F-choline, for imaging evaluation of prostate cancer.

Application of C-11-acetate positron-emission tomography (PET) imaging in prostate cancer: systematic review and meta-analysis of the literature

To review the literature on the application of (11) C-acetate positron-emission tomography (PET) imaging in prostate cancer. We systematically reviewed the available literature and presented the results in meta-analysis format. PubMed, SCOPUS, ISI web of knowledge, Science Direct, Springer, and Google Scholar were searched with 'Acetate AND PET AND Prostate' as keywords. All studies that evaluated accuracy of (11) C-acetate imaging in primary or recurrent prostate cancer were included, if enough data could be extracted for calculation of sensitivity and/or specificity. In all, 23 studies were included in the study. For evaluation of primary tumour, pooled sensitivity was 75.1 (69.8-79.8)% and specificity was 75.8 (72.4-78.9)%. For detection of recurrence, sensitivity was 64 (59-69)% and specificity was 93 (83-98)%. Sensitivity for recurrence detection was higher in post-surgical vs post-radiotherapy patients and in patients with PSA at relapse of >1 ng/mL. Studies using PET/computed tomography vs PET also showed higher sensitivity for detection of recurrence. Imaging with (11) C-acetate PET can be useful in patients with prostate cancer. This is especially true for evaluation of patients at PSA relapse, although the sensitivity is overall low. For primary tumour evaluation (localisation of tumour in the prostate and differentiation of malignant from benign lesions), (11) C-acetate is of limited value due to low sensitivity and specificity. Due to the poor quality of the included studies, the results should be interpreted with caution and further high-quality studies are needed.

Molecular and functional imaging for detection of lymph node metastases in prostate cancer

Knowledge on lymph node metastases is crucial for the prognosis and treatment of prostate cancer patients. Conventional anatomic imaging often fails to differentiate benign from metastatic lymph nodes. Pelvic lymph node dissection is an invasive technique and underestimates the extent of lymph node metastases. Therefore, there is a need for more accurate non-invasive diagnostic techniques. Molecular and functional imaging has been subject of research for the last decades, in this respect. Therefore, in this article the value of imaging techniques to detect lymph node metastases is reviewed. These techniques include scintigraphy, sentinel node imaging, positron emission tomography/computed tomography (PET/CT), diffusion weighted magnetic resonance imaging (DWI MRI) and magnetic resonance lymphography (MRL). Knowledge on pathway and size of lymph node metastases has increased with molecular and functional imaging. Furthermore, improved detection and localization of lymph node metastases will enable (focal) treatment of the positive nodes only.

Evaluation of androgen-induced effects on the uptake of [18F]FDG, [11C]choline and [11C]acetate in an androgen-sensitive and androgen-independent prostate cancer xenograft model

Background

Androgen deprivation (AD) is generally used as a first-line palliative treatment in prostate cancer (PCa) patients with rising prostate-specific antigen (PSA) after primary therapy. To acquire an accurate detection of tumour viability following AD with positron emission tomography (PET), an androgen-independent uptake of tracers would be advantageous. Several metabolic PET tracers are employed for detecting recurrent PCa. We evaluated the effect of AD on the uptake of 2-deoxy-2-[¹⁸F]fluoro-d-glucose ([¹⁸F]FDG), [¹¹C]choline and [¹¹C]acetate in vivo.

Methods

An [¹⁸F]FDG, [¹¹C]choline and [¹¹C]acetate baseline micro(μ)PET/μ computed tomography (CT) scan was subsequently performed in xenografts of androgen-sensitive (LAPC-4) and androgen-independent (22Rv1) tumours in nude mice. An untreated control group was compared to a surgical castration group, i.e. androgen-deprived group. μPET/μCT imaging with the above-mentioned tracers was repeated 5 days after the start of treatment. The percentage change of SUV_max and SUV_meanTH in the tumours was calculated.

Results

AD did not significantly affect the uptake of [¹⁸F]FDG and [¹¹C]choline in LAPC-4 tumours as compared with the uptake of both tracers in untreated tumours. In control 22Rv1 tumours, [¹¹C]choline and [¹⁸F]FDG uptake increased over time. However, compared with the uptake in control tumours, AD significantly decreased the uptake of [¹¹C]choline and tended to decrease [¹⁸F]FDG uptake. [¹¹C]acetate uptake remained unaffected by AD in both PCa xenograft models.

Conclusions

[¹⁸F]FDG and especially [¹¹C]choline PET, which is currently used for the detection of recurrent PCa, could miss or underestimate the presence of local recurrent PCa following AD therapy. [¹¹C]acetate uptake occurs independently of androgens and thus may be more favourable for detecting tumour viability during or following AD.

11C-acetate PET/CT before radical prostatectomy: nodal staging and treatment failure prediction

Despite early detection programs, many patients with prostate cancer present with intermediate- or high-risk disease. We prospectively investigated whether (11)C-acetate PET/CT predicts lymph node (LN) metastasis and treatment failure in men for whom radical prostatectomy is planned.

METHODS

107 men with intermediate- or high-risk localized prostate cancer and negative conventional imaging findings underwent PET/CT with (11)C-acetate. Five underwent LN staging only, and 102 underwent LN staging and prostatectomy. PET/CT findings were correlated with pathologic nodal status. Treatment-failure-free survival was estimated by the Kaplan-Meier method. The ability of PET/CT to predict outcomes was evaluated by multivariate Cox proportional hazards analysis.

RESULTS

PET/CT was positive for pelvic LN or distant metastasis in 36 of 107 patients (33.6%). LN metastasis was present histopathologically in 25 (23.4%). The sensitivity, specificity, and positive and negative predictive values of PET/CT for detecting LN metastasis were 68.0%, 78.1%, 48.6%, and 88.9%, respectively. Treatment failed in 64 patients: 25 with metastasis, 17 with a persistent postprostatectomy prostate-specific antigen level greater than 0.20 ng/mL, and 22 with biochemical recurrence (prostate-specific antigen level > 0.20 ng/mL after nadir) during follow-up for a median of 44.0 mo. Treatment-failure-free survival was worse in PET-positive than in PET-negative patients (P < 0.0001) and in those with false-positive than in those with true-negative scan results (P < 0.01), suggesting that PET may have demonstrated nodal disease not removed surgically or identified pathologically. PET positivity independently predicted failure in preoperative (hazard ratio, 3.26; P < 0.0001) and postoperative (hazard ratio, 3.07; P = 0.0001) multivariate models.

CONCLUSION

In patients planned for or completing prostatectomy, (11)C-acetate PET/CT detects LN metastasis not identified by conventional imaging and independently predicts treatment-failure-free survival.

Antilipolytic drug boosts glucose metabolism in prostate cancer

INTRODUCTION

The antilipolytic drug Acipimox reduces free fatty acid (FFA) levels in the blood stream. We examined the effect of reduced FFAs on glucose metabolism in androgen-dependent (CWR22Rv1) and androgen-independent (PC3) prostate cancer (PCa) xenografts.

METHODS

Subcutaneous tumors were produced in nude mice by injection of PC3 and CWR22Rv1 PCa cells. The mice were divided into two groups (Acipimox vs. controls). Acipimox (50mg/kg) was administered by oral gavage 1h before injection of tracers. 1h after i.v. co-injection of 8.2MBq (222 ± 6.0 μCi) (18)F-FDG and~0.0037 MBq (0.1 μCi) (14)C-acetate, (18)F-FDG imaging was performed using a small-animal PET scanner. Counting rates in reconstructed images were converted to activity concentrations. Quantification was obtained by region-of-interest analysis using dedicated software. The mice were euthanized, and blood samples and organs were harvested. (18)F radioactivity was measured in a calibrated γ-counter using a dynamic counting window and decay correction. (14)C radioactivity was determined by liquid scintillation counting using external standard quench corrections. Counts were converted into activity, and percentage of the injected dose per gram (%ID/g) tissue was calculated.

RESULTS

FDG biodistribution data in mice with PC3 xenografts demonstrated doubled average %ID/g tumor tissue after administration of Acipimox compared to controls (7.21 ± 1.93 vs. 3.59 ± 1.35, P=0.02). Tumor-to-organ ratios were generally higher in mice treated with Acipimox. This was supported by PET imaging data, both semi-quantitatively (mean tumor FDG uptake) and visually (tumor-to-background ratios). In mice with CWR22Rv1 xenografts there was no effect of Acipimox on FDG uptake, either in biodistribution or PET imaging. (14)C-acetate uptake was unaffected in PC3 and CWR22Rv1 xenografts.

CONCLUSIONS

In mice with PC3 PCa xenografts, acute administration of Acipimox increases tumor uptake of (18)F-FDG with general improvements in tumor-to-background ratios. Data indicate that administration of Acipimox prior to (18)F-FDG PET scans has potential to improve sensitivity and specificity in patients with castration-resistant advanced PCa.

Functional imaging for prostate cancer: therapeutic implications

Functional radionuclide imaging modalities, now commonly combined with anatomical imaging modalities computed tomography (CT) or magnetic resonance imaging (single photon emission computed tomography [SPECT]/CT, positron emission tomography [PET]/CT, and PET/magnetic resonance imaging), are promising tools for the management of prostate cancer, particularly for therapeutic implications. Sensitive detection capability of prostate cancer using these imaging modalities is one issue; however, the treatment of prostate cancer using the information that can be obtained from functional radionuclide imaging techniques is another challenging area. There are not many SPECT or PET radiotracers that can cover the full spectrum of the management of prostate cancer from initial detection to staging, prognosis predictor, and all the way to treatment response assessment. However, when used appropriately, the information from functional radionuclide imaging improves, and sometimes significantly changes, the whole course of the cancer management. The limitations of using SPECT and PET radiotracers with regard to therapeutic implications are not so much different from their limitations solely for the task of detecting prostate cancer; however, the specific imaging target and how this target is reliably imaged by SPECT and PET can potentially make significant impact in the treatment of prostate cancer. Finally, although the localized prostate cancer is considered manageable, there is still significant need for improvement in noninvasive imaging of metastatic prostate cancer, in treatment guidance, and in response assessment from functional imaging, including radionuclide-based techniques. In this review article, we present the rationale of using functional radionuclide imaging and the therapeutic implications for each of radionuclide imaging agent that have been studied in human subjects.

Pharmacokinetics, metabolism, biodistribution, radiation dosimetry, and toxicology of (18)F-fluoroacetate ((18)F-FACE) in non-human primates

INTRODUCTION

To facilitate the clinical translation of (18)F-fluoroacetate ((18)F-FACE), the pharmacokinetics, biodistribution, radiolabeled metabolites, radiation dosimetry, and pharmacological safety of diagnostic doses of (18)F-FACE were determined in non-human primates.

METHODS

(18)F-FACE was synthesized using a custom-built automated synthesis module. Six rhesus monkeys (three of each sex) were injected intravenously with (18)F-FACE (165.4 ± 28.5 MBq), followed by dynamic positron emission tomography (PET) imaging of the thoracoabdominal area during 0-30 min post-injection and static whole-body PET imaging at 40, 100, and 170 min. Serial blood samples and a urine sample were obtained from each animal to determine the time course of (18)F-FACE and its radiolabeled metabolites. Electrocardiograms and hematology analyses were obtained to evaluate the acute and delayed toxicity of diagnostic dosages of (18)F-FACE. The time-integrated activity coefficients for individual source organs and the whole body after administration of (18)F-FACE were obtained using quantitative analyses of dynamic and static PET images and were extrapolated to humans.

RESULTS

The blood clearance of (18)F-FACE exhibited bi-exponential kinetics with half-times of 4 and 250 min for the fast and slow phases, respectively. A rapid accumulation of (18)F-FACE-derived radioactivity was observed in the liver and kidneys, followed by clearance of the radioactivity into the intestine and the urinary bladder. Radio-HPLC analyses of blood and urine samples demonstrated that (18)F-fluoride was the only detectable radiolabeled metabolite at the level of less than 9% of total radioactivity in blood at 180 min after the (18)F-FACE injection. The uptake of free (18)F-fluoride in the bones was insignificant during the course of the imaging studies. No significant changes in ECG, CBC, liver enzymes, or renal function were observed. The estimated effective dose for an adult human is 3.90-7.81 mSv from the administration of 185-370 MBq of (18)F-FACE.

CONCLUSIONS

The effective dose and individual organ radiation absorbed doses from administration of a diagnostic dosage of (18)F-FACE are acceptable. From a pharmacologic perspective, diagnostic dosages of (18)F-FACE are non-toxic in primates and, therefore, could be safely administered to human patients for PET imaging.

Ghrelin receptor as a novel imaging target for prostatic neoplasms

BACKGROUND

Ghrelin is a natural growth hormone secretagogue (GHS) that is co-expressed with its receptor GHSR in human prostate cancer (PCa) cells. Imaging probes that target receptors for ghrelin may delineate PCas from benign disease. The specificity of a novel ghrelin-imaging probe for PCa over normal tissue or benign disease was assessed.

METHODS

A fluorescein-bearing ghrelin analogue was synthesized (fluorescein-ghrelin(1-18)), and its application for imaging was evaluated in a panel of PCa cell lines and human prostate tissue. Prostate core biopsy samples were collected from fresh surgery specimens of 13 patients undergoing radical prostatectomy. Ghrelin probe signal was detected and quantified in each sample using a hapten amplification technique and associated with pathological features.

RESULTS

The ghrelin probe was taken up by GHSR-expressing LNCaP and PC-3 cells, and not in BPH cells that express low levels of GHSR. Binding was blocked by competition with excess unlabeled probe. The ghrelin probe signal was 4.7 times higher in PCa compared to benign hyperplasia tissue (P = 0.0027) and normal tissue (P = 0.0093). Furthermore, while the ghrelin probe signal was 1.9-fold higher in PIN compared to benign hyperplasia (P = 0.0022) and normal tissue (P = 0.0047), there was no significant difference in the signal of benign hyperplasia compared to normal tissue.

CONCLUSION

The imaging probe fluorescein-ghrelin(1-18) is specific for PCa, and did not associate significantly with benign hyperplasia or normal prostate tissue. This data suggests that ghrelin analogues may be useful as molecular imaging probes for prostatic neoplasms in both localized and metastatic disease.

Lipids and prostate cancer

The role of lipid metabolism has gained particular interest in prostate cancer research. A large body of literature has outlined the unique upregulation of de novo lipid synthesis in prostate cancer. Concordant with this lipogenic phenotype is a metabolic shift, in which cancer cells use alternative enzymes and pathways to facilitate the production of fatty acids. These newly synthesized lipids may support a number of cellular processes to promote cancer cell proliferation and survival. Hence, de novo lipogenesis is under intense investigation as a therapeutic target. Epidemiologic studies suggest dietary fat may also contribute to prostate cancer; however, whether dietary lipids and de novo synthesized lipids are differentially metabolized remains unclear. Here, we highlight the lipogenic nature of prostate cancer, especially the promotion of de novo lipid synthesis, and the significance of various dietary lipids in prostate cancer development and progression.

Preclinical lymphatic imaging

Noninvasive in vivo imaging of lymphatic vessels and lymphatic nodes is expected to fulfill the purpose of analyzing lymphatic vessels and their function, understanding molecular mechanisms of lymphangiogenesis and lymphatic spread of tumors, and utilizing lymphatic molecular markers as a prognostic or diagnostic indicator. In this review, we provide a comprehensive summary of in vivo imaging modalities for detecting lymphatic vessels, lymphatic drainage, and lymphatic nodes, which include conventional lymphatic imaging techniques such as dyes and radionuclide scintigraphy as well as novel techniques for lymphatic imaging such as optical imaging, computed tomography, magnetic resonance imaging, ultrasound, positron emission tomography using lymphatic biomarkers, photoacoustic imaging, and combinations of multiple modalities. The field of lymphatic imaging is ever evolving, and technological advances, combined with the development of new contrast agents, continue to improve the research of lymphatic vascular system in health and disease states as well as to improve the accuracy of diagnosis in the relevant diseases.

Do androgens control the uptake of 18F-FDG, 11C-choline and 11C-acetate in human prostate cancer cell lines?

PURPOSE

The aim of this study was to evaluate the impact of androgen ablation therapy in different prostate cancer (PCa) cell lines--reflecting different stages of the disease--on (18)F-fluorodeoxyglucose (FDG), 11C-choline and 11C-acetate uptake.

METHODS

Uptake experiments were performed in androgen-sensitive (LNCaP, PC346C) and independent cell lines (22Rv1, PC346DCC, PC-3) as well as in a benign prostatic hyperplasia (BPH-1) cell line. Tracer uptake was assessed under androgen ablation. Results of the cancer cell lines were normalized to those of BPH-1. To evaluate the effect of androgen on the uptake of 18F-FDG, 11C-choline and 11C-acetate in PCa cell lines, 10(-8) M R1881, 10(-10) M R1881, the combination of 10(-10) M R1881 plus 10(-6) M Casodex or 10(-6) M Casodex alone were added in parallel cell cultures 1 day before uptake experiments. Uptake in androgen-supplemented cell cultures was compared to the uptake under androgen deprivation. Uptake was corrected for cell number using protein content.

RESULTS

Compared to BPH-1, a higher 18F-FDG uptake was observed only in PC346C cells, whereas a higher 11C-choline and markedly increased 11C-acetate uptake was seen in all cancer cell lines. Androgens significantly modulated the uptake of 18F-FDG in LNCaP, PC346C and 22Rv1 cells, and of 11C-choline in the PC346C and 22Rv1 cell line. No androgenic effect on 11C-choline and 18F-FDG uptake was observed in PC-3 and PC346DCC cells. 11C-Acetate uptake was independent of androgen status in all PCa cell lines studied.

CONCLUSION

18F-FDG uptake in PCa cell lines showed the highest variability and strongest androgen effect, suggesting its poor potential for metabolic imaging of advanced PCa. In contrast to 18F-FDG and 11C-choline, 11C-acetate uptake was unaffected by androgens and thus 11C-acetate seems best for monitoring PCa progression.

C11-acetate and F-18 FDG PET for men with prostate cancer bone metastases: relative findings and response to therapy

PURPOSE OF THE REPORT

This study tested the feasibility of C11-acetate (acetate) positron emission tomography (PET) imaging to assess response to therapy in men with bone metastatic prostate cancer and compared results for disease detection and response evaluation with F-18 fluorodeoxyglucose (FDG) PET.

MATERIALS AND METHODS

Men with ≥3 prostate cancer bone metastases identified by Tc-99m methylene diphosphonate (MDP) bone scintigraphy and/or computed tomography were enrolled in a prospective study of serial acetate and FDG PET imaging. Patients were imaged before and 6 to 12 weeks after initial androgen deprivation therapy for new metastatic prostate cancer or first-line chemotherapy with docetaxel for castration-resistant prostate cancer. Qualitative assessment and changes in the tumor:normal uptake ratio were used to assess response by both acetate and FDG PET. In addition, the detection of bone metastases pretherapy was compared for acetate and FDG PET.

RESULTS

A total of 8 patients with documented bone metastases were imaged, of which 6 were imaged both pre- and post-therapy. Acetate PET detected bone metastases in all 8 patients, whereas FDG PET detected lesions in 6 of the 7 imaged patients. Acetate PET generally detected more metastases with a higher tumor:normal uptake ratio. Qualitative and quantitative assessments of post-treatment response correlated with composite clinical designations of response, stable disease, or progression in 6 of 6 and 5 of 6 by acetate and 4 of 5 and 3 of 5 by FDG PET, respectively.

CONCLUSIONS

In this pilot study, results indicate that acetate PET holds promise for response assessment of prostate cancer bone metastases and is complementary to FDG PET in bone metastasis detection.

Role of imaging and biopsy to assess local recurrence after definitive treatment for prostate carcinoma (surgery, radiotherapy, cryotherapy, HIFU)

PURPOSE

Defining the site of recurrent disease early after definitive treatment for a localized prostate cancer is a critical issue as it may greatly influence the subsequent therapeutic strategy or patient management.

METHODS

A systematic review of the literature was performed by searching Medline from January 1995 up to January 2011. Electronic searches were limited to the English language, and the keywords prostate cancer, radiotherapy [RT], high intensity focused ultrasound [HIFU], cryotherapy [CRIO], transrectal ultrasound [TRUS], magnetic resonance [MRI], PET/TC, and prostate biopsy were used.

RESULTS

Despite the fact that diagnosis of a local recurrence is based on PSA values and kinetics, imaging by means of different techniques may be a prerequisite for effective disease management. Unfortunately, prostate cancer local recurrences are very difficult to detect by TRUS and conventional imaging that have shown limited accuracy at least at early stages. On the contrary, functional and molecular imaging such as dynamic contrast-enhanced MRI (DCE-MRI), and diffusion-weighted imaging (DWI), offers the possibility of imaging molecular or cellular processes of individual tumors. Recently, PET/CT, using 11C-choline, 18F-fluorocholine or 11C-acetate has been successfully proposed in detecting local recurrences as well as distant metastases. Nevertheless, in controversial cases, it is necessary to perform a biopsy of the prostatic fossa or a biopsy of the prostate to assess the presence of a local recurrence under guidance of MRI or TRUS findings.

CONCLUSION

It is likely that imaging will be extensively used in the future to detect and localize prostate cancer local recurrences before salvage treatment.

Prostate cancer

Prostate cancer is biologically and clinically a heterogeneous disease and its imaging evaluation will need to be tailored to the specific phases of the disease in a patient-specific, risk-adapted manner. We first present a brief overview of the natural history of prostate cancer before discussing the role of various imaging tools, including opportunities and challenges, for different clinical phases of this common disease in men. We then review the preclinical and clinical evidence on the potential and emerging role of positron emission tomography with various radiotracers in the imaging evaluation of men with prostate cancer.