11C-Choline Positron Emission Tomography in Prostate Cancer: Primary Staging and Recurrent Site Staging

Defining Oligometastatic Disease in the New Era of PSMA-PET Imaging for Primary Staging of Prostate Cancer

Oligometastatic prostate cancer has traditionally been defined in the literature as a limited number of metastatic lesions (either to soft tissue or bone), typically based on findings seen on CT, MRI, and skeletal scintigraphy. Although definitions have varied among research studies, many important clinical trials have documented effective treatments and prognostication in patients with oligometastatic prostate cancer. In current clinical practice, prostate-specific membrane antigen (PSMA)-PET/CT is increasingly utilized for the initial staging of high-risk patients and, in many cases, detecting metastases that would have otherwise been undetected with conventional staging imaging. Thus, patients with presumed localized and/or oligometastatic prostate cancer undergo stage migration based on more novel molecular imaging. As a result, it is challenging to apply the data from the era before widespread PET utilization to current clinical practice and to relate current trials using PSMA-PET/CT for disease detection to older studies using conventional staging imaging alone. This manuscript aims to review the definition of oligometastatic prostate cancer, summarize important studies utilizing both PSMA-PET/CT and conventional anatomic imaging, discuss the concept of stage migration, and discuss current problems and challenges with the current definition of oligometastatic disease.

Role of molecular imaging in the detection of localized prostate cancer

Molecular imaging of prostate cancer continues to grow, with recent inclusion of several positron emission tomography (PET) radiotracers into the recent National Comprehensive Cancer Network guidelines and the US Food and Drug Administration approval of prostate-specific membrane antigen (PSMA)-targeted radiotracers. While much of the work for many of these radiotracers is focused on systemic staging and restaging in both newly diagnosed high-risk prostate cancer and biochemically recurrent disease patients, the potential role of molecular imaging for the detection of localized prostate cancer has not yet been fully established. The primary aim of this article will be to present the potential role for molecular imaging in the detection of localized prostate cancer and discuss potential advantages and disadvantages to utilization of both PET/computed tomography (CT) and PET/magnetic resonance imaging (MRI) for this clinical indication of use.

Iodinated Choline Transport-Targeted Tracers

We present a novel series of radioiodinated tracers and potential theranostics for diseases accompanied by pathological function of proteins involved in choline transport. Unlike choline analogues labeled with ¹¹C or ¹⁸F that are currently used in the clinic, the iodinated compounds described herein are applicable in positron emission tomography, single-photon emission computed tomography, and potentially in therapy, depending on the iodine isotope selection. Moreover, favorable half-lives of iodine isotopes result in much less challenging synthesis by isotope exchange reaction. Six of the described compounds were nanomolar ligands, and the best compound possessed an affinity 100-fold greater than that of choline. Biodistribution data of ¹²⁵I-labeled ligands in human prostate carcinoma bearing (PC-3) mice revealed two compounds with a biodistribution profile superior to that of [¹⁸F]fluorocholine.

Localization and restaging of carcinoma prostate by 68Gallium prostate-specific membrane antigen positron emission tomography computed tomography in patients with biochemical recurrence

INTRODUCTION

Radical prostatectomy (RP) and radical radiotherapy (RT) are well established primary curative options for localized prostate cancer. Despite technical improvements, prostate-specific antigen (PSA)-recurrence after RP and RT is a common clinical scenario. We aimed to assess the role of ⁶⁸Gallium (⁶⁸Ga) prostate-specific membrane antigen positron emission tomography computed tomography (PSMA PET/CT) in patients with biochemical recurrence of prostate cancer after RP or RT for the detection and localization recurrent and metastatic disease.

MATERIALS AND METHODS

We ambispectively (70 retrospective and 100 prospective) analyzed the data of men with biochemical recurrence post-RP and post-RT who were evaluated by ⁶⁸Ga PSMA PET/CT at our institute. We aimed to assess the relationship between serum PSA levels and the probability of having a positive scan in patients with recurrent prostate cancer.

RESULTS

The study included 170 men, all had adenocarcinoma of the prostate, 124/170 had previous RP and 46/170 had prior RT. The median serum PSA in the RP group was 1.8 ng/ml and 5.2 ng/ml in the RT group. In the post-RP cohort, the detection rate of ⁶⁸Ga PSMA PET/CT was 39.3% for PSA 0.2 to <0.5 ng/ml, 47.3% for PSA 0.5 to <1 ng/ml, 68.4% for PSA 1 to <2 ng/ml and 93.1% for PSA ≥2 ng/ml. In the post-RT group, the detection rate was 88.8% for PSA 2 to <4 ng/ml and 100% for PSA ≥4 ng/ml.

CONCLUSIONS

⁶⁸Ga PSMA PET/CT provides a novel imaging modality for the detection of prostate cancer recurrence and metastases at low posttreatment PSA levels, which may help in directing appropriate salvage treatments.

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.

Role of 18F-Choline PET/CT in guiding biopsy in patients with risen PSA levels and previous negative biopsy for prostate cancer

OBJECTIVES

To study ¹⁸F-Choline PET/CT in the diagnosis and biopsy guide of prostate cancer (pCa) in patients with persistently high prostate-specific antigen (PSA) and previous negative prostate biopsy. To compare the clinical risk factors and metabolic variables as predictors of malignancy.

METHODS

Patients with persistently elevated PSA in serum (total PSA >4ng/mL) and at least a previous negative or inconclusive biopsy were consecutively referred for a whole body ¹⁸F-Choline PET/CT. Patient age, PSA level, PSA doubling time (PSAdt) and PSA velocity (PSAvel) were obtained. PET images were visually (positive or negative) and semiquantitatively (SUVmax) reviewed. ¹⁸F-Choline uptake prostate patterns were defined as focal, multifocal, homogeneous or heterogeneous. Histology on biopsy using transrectal ultrasound-guided approach was the gold standard. Sensitivity (Se), specificity (Sp) and accuracy (Ac) of PET/CT for diagnosis of pCa were evaluated using per-patient and per-prostate lobe analysis. Receiver-operating-characteristic (ROC) curve analysis was used to assess the value of SUVmax to diagnose pCa. Correlation between PET/CT and biopsy results per-prostate lobe was assessed using the Chi-square test. Univariate and multivariate logistic regression analysis were applied to compare clinical risk factors and metabolic variables as predictors of malignancy.

RESULTS

Thirty-six out of 43 patients with histologic confirmation were included. In 11 (30.5%) patients, pCa was diagnosed (Gleason score from 4 to 9). The mean values of patient age, PSA level, PSAdt and PSAvel were: 65.5 years, 15.6ng/ml, 28.1 months and 8.5ng/mL per year, respectively. Thirty-three patients had a positive PET/CT; 18 had a focal pattern, 7 multifocal, 4 homogeneous and 4 heterogeneous. Se, Sp and Ac of PET/CT were of 100%, 12% and 38% in the patient based analysis, and 87%, 29% and 14% in the prostate lobe based analysis, respectively. The ROC curve analysis of SUVmax showed an AUC of 0.568 (p=0.52). On a lobe analysis, poor agreement was observed between PET/CT findings and biopsy results (p=0.097). In the univariate/multivariate analysis, none of clinical and metabolic variables were statistically significant as predictor of pCa.

CONCLUSION

Choline PET/CT is a suitable procedure for the detection of pCa in highly selected patients, however, a high rate of false positive should be expected.

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.

Initial prostate cancer diagnosis and disease staging--the role of choline-PET-CT

An early and correct diagnosis together with accurate staging of prostate cancer is necessary in order to plan the most appropriate treatment strategy. Morphological imaging modalities such as transrectal ultrasonography (TRUS), CT, and MRI can have some limitations regarding their accuracy for primary diagnosis and staging of prostate cancer; for instance, they have limited specificity in differentiating cancer from benign prostatic conditions and, by using size as the only criterion to characterize lymph node metastases, they might not be accurate enough for tumour characterization. In this scenario, PET-CT with (11)C-labelled or (18)F-labelled choline derivatives provides morphological and functional characterization and could overcome the limitations of the conventional imaging techniques. PET-CT is one of the most investigated molecular imaging modalities for prostate cancer diagnosis and staging. Currently, the main investigations on the role of PET-CT in the diagnosis and staging of prostate cancer have been performed on a retrospective basis and this type of analysis might be one of the main reasons why different results regarding its diagnostic accuracy have been reported.

Evaluation of Hybrid ⁶⁸Ga-PSMA Ligand PET/CT in 248 Patients with Biochemical Recurrence After Radical Prostatectomy

The expression of prostate-specific membrane antigen (PSMA) is increased in prostate cancer. Recently, (68)Ga-PSMA (Glu-NH-CO-NH-Lys-(Ahx)-[(68)Ga(HBED-CC)]) was developed as a PSMA ligand. The aim of this study was to investigate the detection rate of (68)Ga-PSMA PET/CT in patients with biochemical recurrence after radical prostatectomy.

METHODS

Two hundred forty-eight of 393 patients were evaluable for a retrospective analysis. Median prostate-specific antigen (PSA) level was 1.99 ng/mL (range, 0.2-59.4 ng/mL). All patients underwent contrast-enhanced PET/CT after injection of 155 ± 27 MBq of (68)Ga-PSMA ligand. The detection rates were correlated with PSA level and PSA kinetics. The influence of antihormonal treatment, primary Gleason score, and contribution of PET and morphologic imaging to the final diagnosis were assessed.

RESULTS

Two hundred twenty-two (89.5%) patients showed pathologic findings in (68)Ga-PSMA ligand PET/CT. The detection rates were 96.8%, 93.0%, 72.7%, and 57.9% for PSA levels of ≥2, 1 to <2, 0.5 to <1, and 0.2 to <0.5 ng/mL, respectively. Whereas detection rates increased with a higher PSA velocity (81.8%, 82.4%, 92.1%, and 100% in <1, 1 to <2, 2 to <5, and ≥5 ng/mL/y, respectively), no significant association could be found for PSA doubling time (82.7%, 96.2%, and 90.7% in >6, 4-6, and <4 mo, respectively). (68)Ga-PSMA ligand PET (as compared with CT) exclusively provided pathologic findings in 81 (32.7%) patients. In 61 (24.6%) patients, it exclusively identified additional involved regions. In higher Gleason score (≤7 vs. ≥8), detection efficacy was significantly increased (P = 0.0190). No significant difference in detection efficacy was present regarding antiandrogen therapy (P = 0.0783).

CONCLUSION

Hybrid (68)Ga-PSMA ligand PET/CT shows substantially higher detection rates than reported for other imaging modalities. Most importantly, it reveals a high number of positive findings in the clinically important range of low PSA values (<0.5 ng/mL), which in many cases can substantially influence the further clinical management.

Correlation of metabolic tumor volume and 11C-choline uptake with the pathology of prostate cancer: evaluation by use of simultaneously recorded MR and PET images

PURPOSE

This study was conducted to assess the relationship between (11)C-choline uptake and pathologic findings obtained by combined use of magnetic resonance (MR) and positron emission tomography (PET) imaging of patients with prostate cancer.

MATERIALS AND METHODS

We retrospectively evaluated 69 patients with prostate cancer who underwent (11)C-choline PET-CT and magnetic resonance imaging before radical prostatectomy. Combined MR-PET images were acquired to obtain precise anatomic information. The maximum standardized uptake value (SUVmax) and metabolic tumor volume (MTV) were compared with pathologic findings from resected specimens as the reference standard.

RESULTS

The mean and standard deviation of tumor SUVmax and MTV were 3.9 ± 1.8 and 12.9 ± 16.4, respectively. Tumors with high MTV (≧8.2) were more likely to be admixed with prostatic intraepithelial neoplasia (PIN) (p < 0.0001) or hyperplasia (p < 0.0001) in the background than those without these findings. Multiple regression analysis also revealed that the presence of hyperplasia (OR; 4.25, 95% CI 1.25-14.4, p = 0.02) and PIN (OR; 9.22, 95% CI 2.60-32.7, p = 0.001) were associated with tumors with high MTV.

CONCLUSION

We have demonstrated, by pathologic evaluation of patients with prostate cancer, that (11)C-choline uptake volume is greater for prostate cancer admixed with PIN and hyperplasia than that without.

[11C]choline PET/CT impacts treatment decision making in patients with prostate cancer referred for radiotherapy

BACKGROUND

The purpose of our study was to analyze the role of [(11)C]choline-positron emission tomography/computed tomography (cho-PET/CT) in the management of patients with prostate cancer referred for radiotherapy.

PATIENTS AND METHODS

Inclusion criteria for this retrospective study were (1) presence of prostate cancer, (2) referral for first radiotherapy course (for primary or recurrent tumor) between February 2007 and July 2010, and (3) performance of cho-PET/CT. All cho-PET/CT scans were classified according to whether they were positive in the prostate/prostate bed (T), pelvic lymph nodes (N), and distant metastases (M) or negative. Therapeutic strategy based on the cho-PET/CT evaluation was compared with the strategy that would have been proposed had cho-PET/CT imaging not been available, following international and national prostate cancer guidelines.

RESULTS

Eighty-two cho-PET/CT scans performed in 74 patients were analyzed. Cho-PET/CT was positive in 49 studies (60%): T only in 22 (45% of all positive studies); N only in 4 (8%); T in combination with N in 3 (6%); and M in combination with T or N, or both, in 16 (33%). Treatment after positive cho-PET/CT examination included radiotherapy ± androgen deprivation (29 patients), surgery ± radiotherapy (6 patients), androgen deprivation only (8 patients), and other treatment (6 patients). In 22 cases, cho-PET/CT (27%) altered the treatment approach compared with the treatment that would have been adopted in the absence of cho-PET/CT analysis.

CONCLUSION

Cho-PET/CT is valuable in defining the extent of disease and supporting therapeutic decisions in the management of prostate cancer. The therapeutic strategy turned out to be influenced by cho-PET/CT imaging in about one third of the patients included in this study.

The role of 11C-choline and 18F-fluorocholine positron emission tomography (PET) and PET/CT in prostate cancer: a systematic review and meta-analysis

CONTEXT

The role of positron emission tomography (PET) and PET/computed tomography (PET/CT) in prostate cancer (PCa) imaging is still debated, although guidelines for their use have emerged over the last few years.

OBJECTIVE

To systematically review and conduct a meta-analysis of the available evidence of PET and PET/CT using 11C-choline and 18F-fluorocholine as tracers in imaging PCa patients in staging and restaging settings.

EVIDENCE ACQUISITION

PubMed, Embase, and Web of Science (by citation of reference) were searched. Reference lists of review articles and included articles were checked to complement electronic searches.

EVIDENCE SYNTHESIS

In staging patients with proven but untreated PCa, the results of the meta-analysis on a per-patient basis (10 studies, n = 637) showed pooled sensitivity, specificity, and diagnostic odds ratio (DOR) of 84% (95% confidence interval [CI], 68-93%), 79% (95% CI, 53-93%), and 20.4 (95% CI, 9.9-42.0), respectively. The positive and negative likelihood ratios were 4.02 (95% CI, 1.73-9.31) and 0.20 (95% CI, 0.11-0.37), respectively. On a per-lesion basis (11 studies, n = 5117), these values were 66% (95% CI, 56-75%), 92% (95% CI, 78-97%), and 22.7 (95% CI, 8.9-58.0), respectively, for pooled sensitivity, specificity, and DOR; and 8.29 (95% CI, 3.05-22.54) and 0.36 (95% CI, 0.29-0.46), respectively, for positive and negative likelihood ratios. In restaging patients with biochemical failure after local treatment with curative intent, the meta-analysis results on a per-patient basis (12 studies, n = 1055) showed pooled sensitivity, specificity, and DOR of 85% (95% CI, 79-89%), 88% (95% CI, 73-95%), and 41.4 (95% CI, 19.7-86.8), respectively; the positive and negative likelihood ratios were 7.06 (95% CI, 3.06-16.27) and 0.17 (95% CI, 0.13-0.22), respectively.

CONCLUSIONS

PET and PET/CT imaging with 11C-choline and 18F-fluorocholine in restaging of patients with biochemical failure after local treatment for PCa might help guide further treatment decisions. In staging of patients with proven but untreated, high-risk PCa, there is limited but promising evidence warranting further studies. However, the current evidence shows crucial limitations in terms of its applicability in common clinical scenarios.

Tumour volume delineation in prostate cancer assessed by [11C]choline PET/CT: validation with surgical specimens

PURPOSE

PET has been proven to be helpful in the delineation of gross tumour volume (GTV) for external radiation therapy in several tumour entities. The aim of this study was to determine if [(11)C]choline PET could be used to localize the carcinomatous tissue within the prostate in order to specifically target this area for example with high-precision radiation therapy.

METHODS

Included in this prospective study were 20 patients with histological proven prostate carcinoma who underwent [(11)C]choline PET/CT before radical prostatectomy. After surgical resection, specimens were fixed and cut into 5-mm step sections. In each section the area of the carcinoma was delineated manually by an experienced pathologist and digitalized, and the histopathological tumour volume was calculated. Shrinkage due to resection and fixation was corrected using in-vivo and ex-vivo CT data of the prostate. Histopathological tumour location and size were compared with the choline PET data. Different segmentation algorithms were applied to the PET data to segment the intraprostatic lesion volume.

RESULTS

A total of 28 carcinomatous lesions were identified on histopathology. Only 13 (46 %) of these lesions had corresponding focal choline uptake. In the remaining lesions, no PET uptake (2 lesions) or diffuse uptake not corresponding to the area of the carcinoma (13 lesions) was found. In the patients with corresponding PET lesions, no suitable SUV threshold (neither absolute nor relative) was found for GTV segmentation to fit the volume to the histological tumour volume.

CONCLUSION

The choline uptake pattern corresponded to the histological localization of prostate cancer in fewer than 50 % of lesions. Even when corresponding visual choline uptake was found, this uptake was highly variable between patients. Therefore SUV thresholding with standard algorithms did not lead to satisfying results with respect to defining tumour tissue in the prostate.

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.

Choline PET and PET/CT in Primary Diagnosis and Staging of Prostate Cancer

PET and PET/CT using [(11)C]- and [(18)F]-labelled choline derivates is increasingly being used for imaging of primary and recurrent prostate cancer. While PET and PET/CT with [(11)C]- and [(18)F]-labelled choline derivates in patients suffering from biochemical recurrence of prostate cancer has been examined in many studies that demonstrate an increasing importance, its role in the primary staging of prostate cancer is still a matter of debate.Morphological and functional imaging techniques such as CT, MRI and TRUS have demonstrated only limited accuracy for the diagnosis of primary prostate cancer. Molecular imaging with PET and PET/CT could potentially increase accuracy to localize primary prostate cancer. A considerable number of studies have examined the value of PET/CT with [(11)C]- and [(18)F]- labelled choline derivates for the diagnosis of primary prostate cancer with mixed results. Primary prostate cancer can only be detected with moderate sensitivity using [(11)C]- and [(18)F]choline PET and PET/CT. The detection rate depends on the tumour configuration. Detection is also limited by a considerable number of microcarcinomas that cannot be detected due to partial volume effects. Therefore small and in part rind-like tumours can often not be visualized. Furthermore, the differentiation between benign changes like prostatitis, high-grade intraepithelial neoplasia (HGPIN) or prostatic hyperplasia is not always possible. Therefore, at the present time, the routine use of PET/CT with [(11)C]- and [(18)F]-labelled choline derivates cannot be recommended as a first-line screening procedure for primary prostate cancer in men at risk. A potential application of choline PET and PET/CT may be to increase the detection rate of clinically suspected prostate cancer with multiple negative prostate biopsies, for example in preparation of a focused re-biopsy and may play a role in patient stratification with respect to primary surgery and radiation therapy in the future.

Synthesis of oncological [11C]radiopharmaceuticals for clinical PET

Positron emission tomography (PET) is a nuclear medicine modality which provides quantitative images of biological processes in vivo at the molecular level. Several PET radiopharmaceuticals labeled with short-lived isotopes such as (18)F and (11)C were developed in order to trace specific cellular and molecular pathways with the aim of enhancing clinical applications. Among these [(11)C]radiopharmaceuticals are N-[(11)C]methyl-choline ([(11)C]choline), l-(S-methyl-[(11)C])methionine ([(11)C]methionine) and 1-[(11)C]acetate ([(11)C]acetate), which have gained an important role in oncology where the application of 2-[(18)F]fluoro-2-deoxy-d-glucose ([(18)F]FDG) is suboptimal. Nevertheless, the production of these radiopharmaceuticals did not reach the same level of standardization as for [(18)F]FDG synthesis. This review describes the most recent developments in the synthesis of the above-mentioned [(11)C]radiopharmaceuticals aiming to increase the availability and hence the use of [(11)C]choline, [(11)C]methionine and [(11)C]acetate in clinical practice.

Restricted water diffusibility as measured by diffusion-weighted MR imaging and choline uptake in (11)C-choline PET/CT are correlated in pelvic lymph nodes in patients with prostate cancer

PURPOSE

(11)C-Choline-positron emission tomography (PET)/computed tomography (CT) is increasingly used in patients with prostate cancer. Another promising technique for assessment of tumor biology is diffusion-weighted MR imaging (DWI). The aim of the study was to compare the functional parameters standardized uptake value (SUV) in PET and apparent diffusion coefficient (ADC) value in DWI of lymph nodes in prostate cancer patients.

PROCEDURES

Fourteen patients with prostate cancer underwent DWI at 1.5T and (11)C-Choline-PET/CT. ADC values and SUVs of all lymph nodes larger than 5 mm (n = 55) were compared by using linear regression analysis. Performance of DWI and (11)C-Choline PET was assessed by receiver operator characteristic curve analysis using histopathology or clinical follow-up as standard of reference.

RESULTS

ADC values and SUV showed a moderate but highly significant inverse correlation (r = -0.5144, p < 0.0001). In lymph nodes with low ADC values, the dispersion of SUV was more pronounced. Moreover, a highly significant difference was observed for mean ADC values and SUV in lymph nodes considered as benign or malignant by follow-up/histopathology (ADC 1.60 ± 0.24 vs. 1.09 ± 0.23 × 10(-3) mm(2)/s; SUV 1.82 ± 0.57 vs. 4.68 ± 03.12; p < 0.0001, respectively).

CONCLUSION

These pilot data propose the ADC value in DWI as a new potential imaging biomarker which might provide additional information on tumor pathophysiology compared to the SUV in (11)C-Choline PET/CT.

Influence of (11)C-choline PET/CT on the treatment planning for salvage radiation therapy in patients with biochemical recurrence of prostate cancer

BACKGROUND AND PURPOSE

The present study evaluates the incidence of (11)C-choline PET/CT positive findings in patients with recurrent prostate cancer referred for salvage radiotherapy (SRT) and the influence on the definition of the planning target volume (PTV).

MATERIAL AND METHODS

Thirty-seven patients treated with radical prostatectomy and referred to SRT to the prostatic fossa because of biochemical relapse, were analysed retrospectively. All patients underwent (11)C-choline PET/CT before radiotherapy. The influence of PET/CT on the extent of the PTV was analysed. The median total follow up after SRT was 51.2 months.

RESULTS

11/37 (30%) patients had a positive finding in the (11)C-choline PET/CT, 5 (13%) outside of the prostatic fossa (iliac lymph nodes), implicating an extension of the PTV. Patients with positive (11)C-choline PET/CT had a significant higher PSA value than patients with no pathologic uptake (p=0.03). Overall, at the end of follow up 56% of the patients had a PSA ≤ 0.2ng/ml and 44% had a biochemical relapse of prostate cancer.

CONCLUSIONS

(11)C-choline PET/CT detects abnormalities outside of the prostatic fossa in 13% of patients referred for SRT because of biochemical relapse after radical prostatectomy, affecting the extent of the PTV. Prospective studies need to be implemented to evaluate the benefit of SRT with a PTV based on (11)C-choline PET/CT.

Imaging of prostate cancer with PET/CT and radioactively labeled choline derivates

PET- and PET/CT using [(11)C]- and [(18)F]-labeled choline derivates are increasingly being used for imaging of prostate cancer. The value of PET- and PET/CT with [(11)C]- and [(18)F]-labeled choline derivates in biochemical recurrence of prostate cancer has been examined in many studies and demonstrates an increasing importance. PET/CT, in comparison to PET, improves especially the lesion localization as well as characterization. Primary prostate cancer can be detected with moderate sensitivity using PET and PET/CT using [(11)C]- and [(18)F]-labeled choline derivates--the differentiation between benign prostatic hyperplasia, prostatitis, or high-grade intraepithelial neoplasia (HGPIN) is not always possible. At the present time, [(11)C]-choline PET/CT is not recommended in the primary setting but may be utilized in clinically suspected prostate cancer with repeatedly negative prostate biopsies, in preparation of a focused re-biopsy. Promising results have been obtained for the use of PET and PET/CT with [(11)C]- and [(18)F]-labeled choline derivates in patients with biochemical recurrence. The detection rate of choline PET and PET/CT for local, regional, and distant recurrence in patients with a biochemical recurrence shows a linear correlation with PSA value at the time of imaging and reaches about 75% in patients with PSA > 3 ng/ml. Even at PSA values below 1 ng/ml, the recurrence can be diagnosed with choline PET/CT in approximately one-third of the patients. PET and PET/CT with [(11)C]- and [(18)F]-choline derivates can be helpful in the clinical setting for choosing a therapeutic strategy in the sense of an individualized treatment: an early diagnosis of recurrence is crucial to the choice of optimal treatment. Especially important for the choice of treatment is the exact localization of the site of recurrence: local recurrence, recurrence as lymph node metastasis, or systemic recurrence, as it has direct influence on individual therapy. This article reviews the use of PET and PET/CT with [(11)C]- and [(18)F]-labeled choline derivates in prostate cancer imaging with special emphasis on patients with biochemical recurrence. We briefly provide an overview of PET tracers for prostate cancer imaging, the rationale of using choline derivatives for prostate cancer imaging and discuss the contribution of choline PET/CT in patients suffering from prostate cancer with an emphasis on recurrent disease. Furthermore, we provide an outlook on future prospects of choline PET/CT imaging for therapy guidance and monitoring in the framework of therapy individualization.

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.

PET/CT Imaging and Radioimmunotherapy of Prostate Cancer

Prostate cancer is a common cancer in men and continues to be a major health problem. Imaging plays an important role in the clinical management of patients with prostate cancer. An important goal for prostate cancer imaging is more accurate disease characterization through the synthesis of anatomic, functional, and molecular imaging information. Positron emission tomography (PET)/computed tomography (CT) in oncology is emerging as an important imaging tool. The most common radiotracer for PET/CT in oncology, (18)F-fluorodeoxyglucose (FDG), is not very useful in the imaging of prostate cancer. However, in recent years other PET tracers have improved the accuracy of PET/CT imaging of prostate cancer. Among these, choline labeled with (18)F or (11)C, (11)C-acetate, and (18)F-fluoride has demonstrated promising results, and other new radiopharmaceuticals are under development and evaluation in preclinical and clinical studies. Large prospective clinical PET/CT trials are needed to establish the role of PET/CT in prostate cancer patients. Because there are only limited available therapeutic options for patients with advanced metastatic prostate cancer, there is an urgent need for the development of more effective treatment modalities that could improve outcome. Prostate cancer represents an attractive target for radioimmunotherapy (RIT) for several reasons, including pattern of metastatic spread (lymph nodes and bone marrow, sites with good access to circulating antibodies) and small volume disease (ideal for antigen access and antibody delivery). Furthermore, prostate cancer is also radiation sensitive. Prostate-specific membrane antigen is expressed by virtually all prostate cancers, and represents an attractive target for RIT. Antiprostate-specific membrane antigen RIT demonstrates antitumor activity and is well tolerated. Clinical trials are underway to further improve upon treatment efficacy and patient selection. This review focuses on the recent advances of clinical PET/CT imaging and RIT of prostate cancer.

Clinical evidence on PET/CT for radiation therapy planning in prostate cancer

The present chapter is focused on the role of positron emission tomography/computed tomography (PET/CT) and [11C]-labelled Choline ([11C]Choline) for the management of prostate cancer patients for radiation therapy planning. Although still a matter of debate, PET/CT with [11C]Choline is not routinely recommended for selecting patients for prostate cancer primary radiation treatment. However, due to its high accuracy in detecting and localizing recurrences when a biochemical failure occurs, [11C]Choline PET/CT may play a role in the re-staging phase to distinguish patients with local versus distant relapse, thus influencing patient management (curative versus palliative therapy). Limited data are currently available on the role of [11C]Choline PET/CT in target volume selection and delineation. According to available literature, [11C]Choline PET/CT is not clinically recommendable to plan target volume both for primary prostate treatment and for local recurrence. Nevertheless, promising data suggested a potential role of [11C]Choline PET/CT as an image guide tool for the irradiation of prostate cancer relapse.

Imaging localized prostate cancer: current approaches and new developments

OBJECTIVE

Prostate cancer is the most common noncutaneous malignancy among men in the Western world. Imaging has recently become more important in the diagnosis, local staging, and treatment follow-up of prostate cancer. In this article, we review conventional and functional imaging methods as well as targeted imaging approaches with novel tracers used in the diagnosis and staging of prostate cancer.

CONCLUSION

Although prostate cancer is the second leading cause of cancer death in men, imaging of localized prostate cancer remains limited. Recent developments in imaging technologies, particularly MRI and PET, may lead to significant improvements in lesion detection and staging.

Characterization of preclinical models of prostate cancer using PET-based molecular imaging

PURPOSE

Transgenic adenocarcinoma of the mouse prostate (TRAMP) mice spontaneously develop hormone-dependent and hormone-independent prostate cancer (PC) that potentially resembles the human pathological condition. The aim of the study was to validate PET imaging as a reliable tool for in vivo assessment of disease biology and progression in TRAMP mice using radioligands routinely applied in clinical practice: [(18)F]FDG and [(11)C]choline.

METHODS

Six TRAMP mice were longitudinally evaluated starting at week 11 of age to visualize PC development and progression. The time frame and imaging pattern of PC lesions were subsequently confirmed on an additional group of five mice.

RESULTS

PET and [(18)F]FDG allowed detection of PC lesions starting from 23 weeks of age. [(11)C]Choline was clearly taken up only by TRAMP mice carrying neuroendocrine lesions, as revealed by post-mortem histological evaluation.

CONCLUSION

PET-based molecular imaging represents a state-of-the-art tool for the in vivo monitoring and metabolic characterization of PC development, progression and differentiation in the TRAMP model.

[(11)C]choline PET/CT in prostate cancer patients with biochemical recurrence after radical prostatectomy

OBJECTIVE

To evaluate [(11)C]choline positron emission tomography/computed tomography ([(11)C]choline PET/CT) for the detection of a biochemical recurrence of prostate cancer after radical prostatectomy.

METHODS

Retrospective analysis of [(11)C]choline PET/CT performed in 41 consecutive prostate cancer patients with a rising PSA. The mean time to biochemical relapse was 24 months. PSA levels were determined at time of examination, and patients received either a targeted biopsy or surgery. Histopathology reports served as reference for the evaluation of the [(11)C]choline PET/CT findings.

RESULTS

Mean PSA in [(11)C]choline PET/CT positive patients was 3.1 ng/ml (median 2.2 ng/ml, range 0.5-11.6 ng/ml) and 0.86 ng/ml in [(11)C]choline PET/CT negative patients (median 0.83 ng/ml, range 0.41-1.40 ng/ml). Six of 12 patients with PSA < 1.5 ng/ml [(11)C]choline PET/CT revealed a pathological uptake. Histopathology was positive in 6/12 patients in this group. At PSA levels ranging from 1.5 to 2.5 ng/ml all [(11)C]choline PET/CT were positive (n = 16), a positive histology was found in 12/16 patients (75%) and at PSA 2.5-5 ng/ml [(11)C]choline PET/CT was positive in 8/8 patients, confirmed by histology in 7/8 patients. Finally, at PSA higher than 5 ng/ml [(11)C]choline PET/CT identified 5/5 patients positive all confirmed by histology. The sensitivity of [(11)C]choline PET/CT for the detection of recurrence at PSA < 2.5 ng/ml was 89% with a positive predictive value of 72%.

CONCLUSION

[(11)C]choline PET/CT is useful for re-staging of prostate cancer in patients with rising PSA even at levels below 1.5 ng/ml. Our study confirms results from other published studies on [(11)C]choline PET/CT in prostate cancer relapse.

Endorectal magnetic resonance imaging at 1.5 Tesla to assess local recurrence following radical prostatectomy using T2-weighted and contrast-enhanced imaging

To evaluate diagnostic performance of endorectal magnetic resonance (eMR) for diagnosing local recurrence of prostate cancer (PC) in patients with previous radical prostatectomy (RP) and to assess whether contrast-enhanced (CE)-eMR improved diagnostic accuracy in comparison to unenhanced study. Unenhanced eMR data of 72 male patients (mean of total PSA: 1.23 +/- 1.3 ng/ml) with previous RP were interpreted retrospectively and classified either as normal or suspicious for local recurrence. All eMR examinations were re-evaluated also on CE-eMR 4 months after the first reading. Images were acquired on a 1.5-T system. These data were compared to the standard of reference for local recurrence: prostatectomy bed biopsy results; choline positron emission tomography results; PSA reduction or increase after pelvic radiotherapy; PSA modification during active surveillance. Sensitivity, specificity, predictive positive value, negative predictive value and accuracy were 61.4%, 82.1%, 84.4%, 57.5% and 69.4% for unenhanced eMR and 84.1%, 89.3%, 92.5%, 78.1% and 86.1% for CE-eMR. A statistically significant difference was found between accuracy and sensitivity of the two evaluations (chi(2) = 5.33; p = 0.02 and chi(2) = 9.00; p = 0.0027). EMR had great accuracy for visualizing local recurrence of PC after RP. CE-eMR improved diagnostic performance in comparison with T2-weighted imaging alone.

Role of whole-body 18F-choline PET/CT in disease detection in patients with biochemical relapse after radical treatment for prostate cancer

PURPOSE

The aim of this study was to evaluate the role of whole body 18F-choline (FCH) positron emission tomography-computed tomography (PET-CT) in detecting and localising disease recurrence in patients presenting biochemical relapse after radical treatment for prostate cancer.

MATERIALS AND METHODS

Fifty-six consecutive patients with increased serum prostate-specific antigen (PSA) levels after radical prostatectomy were included in the study. None of them was receiving hormone treatment at the time of the examination or had been treated during the previous 6 months. All patients underwent whole-body 18F-choline PET imaging, and the pathological findings were compared with those of further imaging exams, biopsy and follow-up. On the basis of the PSA levels, we divided our patient population into three subgroups: PSA < or = 1, 1 < PSA < or = 5, and PSA > 5 ng/ml.

RESULTS

Overall, the PET scan detected disease relapse in 42.9% of cases (24/56). PET sensitivity was closely related to serum PSA levels, showing values of 20%, 44% and 81.8% in the PSA < or = 1, 1 < PSA < or = 5 and PSA > 5 ng/ml subgroups, respectively.

CONCLUSIONS

In patients with biochemical relapse after radical treatment for prostate cancer, 18F-choline PET-CT represents a single step, whole-body, noninvasive study that allows disease detection and localisation. The disease detection rate is related to serum PSA levels.

[(11)C]choline uptake with PET/CT for the initial diagnosis of prostate cancer: relation to PSA levels, tumour stage and anti-androgenic therapy

PURPOSE

The accuracy of positron emission tomography (PET)/CT with [(11)C]choline for the detection of prostate cancer is not well established. We assessed the dependence of [(11)C]choline maximum standardized uptake values (SUV(max)) in the prostate gland on cell malignancy, prostate-specific antigen (PSA) levels, Gleason score, tumour stage and anti-androgenic hormonal therapy.

METHODS

In this prospective study, PET/CT with [(11)C]choline was performed in 19 prostate cancer patients who subsequently underwent prostatectomy with histologic sextant analysis (group A) and in six prostate cancer patients before and after anti-androgenic hormonal therapy (bicalutamide 150 mg/day; median treatment of 4 months; group B).

RESULTS

In group A, based on a sextant analysis with a [(11)C]choline SUV(max) cutoff of 2.5 (as derived from a receiver-operating characteristic analysis), PET/CT showed sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 72, 43, 64, 51 and 60%, respectively. In the patient-by-patient analysis, no significant correlation was detected between SUV(max) and PSA levels, Gleason score or pathological stage. On the contrary, a significant (P < 0.05) negative correlation was detected between SUV(max) and anti-androgenic therapy both in univariate (r (2) = 0.24) and multivariate (r (2) = 0.48) analyses. Prostate [(11)C]choline uptake after bicalutamide therapy significantly (P < 0.05) decreased compared to baseline (6.4 +/- 4.6 and 11.8 +/- 5.3, respectively; group B).

CONCLUSION

PET/CT with [(11)C]choline is not suitable for the initial diagnosis and local staging of prostate cancer. PET/CT with [(11)C]choline could be used to monitor the response to anti-androgenic therapy.

The roles of PET and PET/CT in the diagnosis and management of prostate cancer

2-(18)F-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) imaging in prostate cancer is challenging because glucose utilization in well-differentiated prostate cancer is often lower than in other tumor types. Nonetheless, FDG-PET has a high positive predictive value for untreated metastases in viscera, but not lymph nodes. A positive FDG-PET can provide useful information to aid the clinician's decision on future management in selected patients who have low prostate-specific antigen levels and visceral changes as a result of metastases. On the other hand, FDG-PET is limited in the identification of prostate tumors, as normal urinary excretion of radioisotope can mask pathological uptake. Moreover, there is an overlap in the degree of uptake between prostate cancer, benign prostatic hyperplasia and inflammation. The tracer choice is also important. (11)C-choline has the advantage of reduced urinary excretion, and thus (11)C-choline PET may provide more accurate information on the localization of main primary prostate cancer lesions than MRI or MR spectroscopy. (11)C-choline PET is sensitive and accurate in the preoperative staging of pelvic lymph nodes in prostate cancer. A few studies are available but there were no PET or PET/CT studies with a large number of patients for tissue confirmation of prostate cancer; further investigations are required.

Conventional and novel PET tracers for imaging in oncology in the era of molecular therapy

In the last ten years, the development of several novel targeted drugs and the refinement of state of the art technologies such as the genomics and proteomics and their introduction to clinical practice have revolutionized the management of patients affected by cancer. However, everyday practice points out several clinical questions: the difficulty of response assessment to new drugs especially using standard RECIST criteria that do not provide information on biological, vascular or metabolic variations; the inadequate selection of patients who are likely to benefit from a targeted therapy excluding those with breast cancer and gastrointestinal stromal tumours; the need to know the global biological background of diseases especially in metastatic setting using repeatable non-invasive procedures. Molecular imaging could provide information on in vivo distribution of biological markers in response to targeted therapy and could improve the selection of patients before therapies. The aim of this review is to analyze the current role of conventional and innovative positron emission tomography (PET) radiotracers in clinical practice and to explore the promising perspectives of molecular imaging in cancer research.

Positron emission tomography and positron emission tomography/computerized tomography of urological malignancies: an update review

PURPOSE

Appropriate imaging in uro-oncology is a crucial component at primary diagnosis, followup and recurrence to achieve an accurate assessment of the disease and determine the most effective treatment. We summarize recent developments in positron emission tomography and positron emission tomography/computerized tomography for prostate, bladder and renal cancer.

MATERIALS AND METHODS

The recent published literature on positron emission tomography and positron emission tomography/computerized tomography in uro-oncology was searched and reviewed.

RESULTS

For prostate cancer 18F-fluorodeoxyglucose is not highly effective for primary diagnosis but it has a limited role in staging and recurrence detection. Promising results have been shown by 11C-choline, 18F-fluorocholine, 11C-acetate and 18F-fluoride. The role of 11C-methionine, 18F-fluoro-5-alpha-dihydrotestosterone and anti-1-amino-3-18F-fluorocyclobutane-1-carboxylic acid remains to be elucidated. For bladder cancer 18F-fluorodeoxyglucose positron emission tomography is useful for identifying distant metastases but not for detecting primary tumors due to the urinary excretion of 18F-fluorodeoxyglucose. The role of 11C-choline and 11C-methionine remains to be evaluated further in clinical studies. For renal cancer 18F-fluorodeoxyglucose is of limited use for primary diagnosis but it has a role in staging and restaging of the disease. More clinical data are needed to investigate the roles of 18F-fluoromisonidazole and 18F-fluorothymidine.

CONCLUSIONS

Several advances in positron emission tomography and positron emission tomography/computerized tomography for urological cancer have been made in recent years. However, larger clinical trials are needed to establish the role of this imaging method for urological malignancy. In the near future the new radiotracers and further advancement in this imaging technique are expected to improve the performance of positron emission tomography/computerized tomography in uro-oncology.

Current concepts on imaging in radiotherapy

New high-precision radiotherapy (RT) techniques, such as intensity-modulated radiation therapy (IMRT) or hadrontherapy, allow better dose distribution within the target and spare a larger portion of normal tissue than conventional RT. These techniques require accurate tumour volume delineation and intrinsic characterization, as well as verification of target localisation and monitoring of organ motion and response assessment during treatment. These tasks are strongly dependent on imaging technologies. Among these, computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (US) and positron emission tomography (PET) have been applied in high-precision RT. For tumour volume delineation and characterization, PET has brought an additional dimension to the management of cancer patients by allowing the incorporation of crucial functional and molecular images in RT treatment planning, i.e. direct evaluation of tumour metabolism, cell proliferation, apoptosis, hypoxia and angiogenesis. The combination of PET and CT in a single imaging system (PET/CT) to obtain a fused anatomical and functional dataset is now emerging as a promising tool in radiotherapy departments for delineation of tumour volumes and optimization of treatment plans. Another exciting new area is image-guided radiotherapy (IGRT), which focuses on the potential benefit of advanced imaging and image registration to improve precision, daily target localization and monitoring during treatment, thus reducing morbidity and potentially allowing the safe delivery of higher doses. The variety of IGRT systems is rapidly expanding, including cone beam CT and US. This article examines the increasing role of imaging techniques in the entire process of high-precision radiotherapy.

Evaluation of [11C]-choline positron-emission/computed tomography in patients with increasing prostate-specific antigen levels after primary treatment for prostate cancer

OBJECTIVE

To evaluate [(11)C]-choline positron-emission tomography (PET)/computed tomography (CT) for detecting clinical recurrence after primary treatment for prostate cancer.

PATIENTS AND METHODS

In all, 50 patients with prostate cancer who had had initial therapy (radical prostatectomy in 40, external beam radiation in three and interstitial brachytherapy in seven) had PET/CT using [(11)C]-choline in the presence of an increased or increasing prostate-specific antigen (PSA) level. The mean (range) time to biochemical progression was 22 (2-136) months. Current PSA levels were determined in all patients at the time of examination. The results were correlated with the histopathology reports after targeted biopsy or surgery, and with the clinical follow-up.

RESULTS

The mean (median, range) PSA level in patients with positive PET/CT was 3.62 (2.42, 0.5-13.1) ng/mL, and that in patients with a negative scan was 0.90 (0.95, 0.41-1.40) ng/mL. PET/CT was positive in seven of 13 patients with a PSA level of <1.5 ng/mL, and histology was positive in this group in nine. In 17 patients with PSA levels of 1.5-2.5 ng/mL PET/CT was positive in all and the histology was positive in 13; in 11 men with a PSA level of 2.5-5 ng/mL PET/CT was positive in all 11 and the histology was positive in 10; in nine men with PSA levels of >5 ng/mL PET/CT identified all as positive and the histology was positive in eight. The sensitivity at a PSA level of <2.5 ng/mL of PET/CT for detecting recurrence was 91% (95% confidence interval, 71-99%) with a specificity of 50% (16-84)%.

CONCLUSION

[(11)C]-choline PET/CT seems to be useful for re-staging prostate cancer after curative therapy and with increasing PSA levels; this was verified by histological examination. We recommend this method at PSA levels of <2.5 ng/mL.

The detection rate of [11C]choline-PET/CT depends on the serum PSA-value in patients with biochemical recurrence of prostate cancer

PURPOSE

An increase of the serum PSA-level is a sensitive in vitro marker for recurrent prostate cancer. However, it remains difficult to differentiate between local, regional or distant recurrent disease. The aim of this study was to assess the relationship between the detection rate of [(11)C]Choline-PET/CT and the serum PSA-level in patients with a biochemical recurrence of prostate cancer with the view towards localisation of recurrent disease.

METHODS

Sixty-three patients (mean age, 68.8 +/- 6.9; range, 45-83 years) with biochemical recurrence after primary therapy for prostate cancer were included in the analysis. Mean PSA-levels were 5.9 +/- 9.7 ng/ml (range, 0.2-39 ng/ml; median, 2.15). Of the 63 patients, 17 were under anti-androgen therapy at the time of [(11)C]Choline PET/CT. Patients underwent a [(11)C]Choline-PET/CT study after injection of 656 +/- 119 MBq [(11)C]Choline on a Sensation 16 Biograph PET/CT scanner.

RESULTS

Of the 63 patients, 35 (56%) showed a pathological [(11)C]Choline uptake. The detection rate of [(11)C]Choline-PET/CT showed a relationship with the serum PSA-level: The detection rate was 36% for a PSA-value <1 ng/ml, 43% for a PSA-value 1-<2 ng/ml, 62% for a PSA-value 2-<3 ng/ml and 73% for a PSA-value >or=3 ng/ml. Anti-androgen therapy did not show a significant effect on the detection rate of [(11)C]Choline-PET/CT (p = 0.374).

CONCLUSION

As an important result our study shows that even for PSA-values <1.0 ng/ml the detection efficiency of [(11)C]Choline-PET/CT is 36%. Furthermore, the detection rate of [(11)C]Choline-PET/CT shows a positive relationship with serum PSA-levels in patients with biochemical recurrence of prostate cancer after primary therapy. Therefore, in these patients, [(11)C]Choline PET/CT allows not only to diagnose but also to localise recurrent disease with implications on disease management (localised vs systemic therapy).

[11C]choline PET/CT imaging in occult local relapse of prostate cancer after radical prostatectomy

PURPOSE

The aim of this study was to assess the accuracy and clinical impact of [(11)C]choline PET/CT for localizing occult relapse of prostate adenocarcinoma after radical prostatectomy.

METHODS

Fourty-nine patients with prostate adenocarcinoma, radical prostatectomy, no evidence of metastatic disease, and occult relapse underwent [(11)C]choline PET/CT. Thirty-six of the patients had biochemical evidence and histological evaluation of local recurrence. Thirteen patients had PSA < 0.3 ng/ml and no evidence of active disease after 1 year follow-up. Focal nodular [(11)C]choline uptake in the prostatic fossa was visually assessed and graded on a five point scale. Maximum standardized radioactivity uptake value (SUV(max)) and the lesion size were measured. A receiver operating characteristic (ROC) analysis was performed and the clinical impact of the PET/CT study was determined.

RESULTS

[(11)C]choline PET/CT was true positive in 23/33 patients and true negative in 12/13 controls. SUV(max) of local recurrence was 3.0 (median, range 0.6-7.4) and 1.1 (0.4-1.6) in controls (p = 0.0002). Lesion size was 1.7 cm (range 0.9-3.7). Area under the ROC curve for detecting relapse was 0.90 +/- 0.05 and 0.83 +/- 0.06 for visual evaluation and SUV(max), respectively. Sensitivity and specificity of [(11)C]choline PET/CT were 0.73 and 0.88, respectively. [(11)C]choline PET/CT identified 12/17 (71%) patients with a favourable biochemical response to local radiotherapy at 2 year (median, 0.8-3.2 range) follow-up.

CONCLUSIONS

Focally increased [(11)C]choline uptake in the prostatic bed reliably predicted local low volume occult relapsing prostate adenocarcinoma after radical prostatectomy and identified 71% of patients with a favourable biochemical response to local radiotherapy.