Is the detection rate of 18F-choline PET/CT influenced by androgen-deprivation therapy?

Molecular Imaging Assessment of Androgen Deprivation Therapy in Prostate Cancer

Hormonal therapy has long been recognized as a mainstay treatment for prostate cancer. New generation imaging agents have provided unprecedented opportunities at all phases along the natural history of prostate cancer. We review the literature on the effect of androgens and androgen deprivation therapy on prostate tumor at its various biological phases using the new generation molecular imaging agents in conjunction with positron emission tomography.

A Retrospective Comparative Study of Sodium Fluoride (NaF-18)-PET/CT and Fluorocholine (F-18-CH) PET/CT in the Evaluation of Skeletal Metastases in Metastatic Prostate Cancer Using a Volumetric 3-D Radiomics Analysis

Bone metastases are common in prostate cancer (PCa). Fluorocholine-18 (FCH) and sodium fluoride-18 (NaF) have been used to assess PCa associated skeletal disease in thousands of patients by demonstrating different mechanism of uptake-cell membrane (lipid) synthesis and bone mineralization. Here, this difference is characterized quantitatively in detail. Our study cohort consisted of 12 patients with advanced disease (> 5 lesions) (M) and of five PCa patients with no skeletal disease (N). They had routine PET/CT with FCH and NaF on consecutive days. Skeletal regions in CT were used to co-register the two PET/CT scans. Bone 3-D volume of interest (VOI) was defined on the CT of PET with a threshold of HU > 150, and sclerotic/dense bone as HU > 600, respectively. Additional VOIs were defined on PET uptake with the threshold values on both FCH (SUV > 3.5) and NaF (SUV > 10). The pathologic skeletal volumes for each technique (CT, HU > 600), NaF (SUV > 10) and FCH (SUV > 3.5) were developed and analyzed. The skeletal VOIs varied from 5.03 L to 7.31 L, whereas sclerotic bone VOIs were from 0.88 L to 2.99 L. Total choline kinase (cell membrane synthesis) activity for FCH (TCA) varied from 0.008 to 4.85 [kg] in M group and from 0.0006 to 0.085 [kg] in N group. Total accelerated osteoblastic (bone demineralization) activity for NaF (TBA varied from 0.25 to 13.6 [kg] in M group and varied from 0.000 to 1.09 [kg] in N group. The sclerotic bone volume represented only 1.86 ± 1.71% of the pathologic FCH volume and 4.07 ± 3.21% of the pathologic NaF volume in M group, and only 0.08 ± 0.09% and 0.18 ± 0.19% in N group, respectively. Our results suggest that CT alone cannot be used for the assessment of the extent of active metastatic skeletal disease in PCa. NaF and FCH give complementary information about the activity of the skeletal disease, improving diagnosis and disease staging.

10-Year Clinical Experience With 18F-Choline PET/CT: An Italian Multicenter Retrospective Assessment of 3343 Patients

PURPOSE

The primary aim of this multicenter retrospective analysis is to examine the role of F-choline PET/CT as a diagnostic tool for staging and restaging prostate cancer (PCa) in a large population in the light of 10 years of clinical experience. A secondary aim of the study is to produce data on the predictors of a positive F-choline PET/CT result in the setting of PCa primaries and biochemical recurrences.

MATERIALS AND METHODS

This multicenter retrospective cohort study is based on data collected by 9 Italian nuclear medicine departments. Between October 2008 and September 2019, 3343 men underwent F-choline PET/CT scans before receiving definitive treatments for a primary PCa or biochemical recurrence. Inclusion criteria were (1) histologically proven PCa (on surgical specimens or prostate biopsies from patients not treated surgically) and (2) availability of clinical and pathological data, including serum prostate specific antigen (PSA) level at the time of PET/CT scanning.

RESULTS

F-choline PET/CT was performed in 545 cases (16.4%) for cancer staging and in 2798 (83.6%) for restaging purposes, and the result was positive in 540 (99.1%) for the former and 1993 (71.2%) for the latter. A positive PET/CT result was always associated with a high Gleason score (>7) and high PSA levels (P < 0.01). The percentage of patients with a PSA threshold less than 1.0 ng/mL for performing PET/CT was higher in the years 2014 to 2019 (n = 341, 25% of cases) than during the previous period (n = 148, 16%; in 2008-2013). When used for staging purposes, receiver operating characteristic analysis showed that PSA levels of 9.2, 16.4, and 16.6 ng/mL were the optimal cutoffs for distinguishing between positive and negative PET/CT findings for local disease, lymph node involvement, and metastasis, respectively. In the restaging setting, a PSA level of 1.27 ng/mL was the optimal cutoff for distinguishing between a positive and negative PET/CT scan.

CONCLUSIONS

F-choline PET/CT can help identify early recurrences, even in the case of low PSA levels (<1 ng/mL). Our data suggest that important improvements have been made in the interpretation of F-choline images and in patient selection in the last 5 years.

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

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

Molecular imaging of prostate cancer: Review of imaging agents, modalities, and current status

INTRODUCTION

The clinical course of Prostate cancer (PCa) are markedly diverse, ranging from indolent to highly aggressive disseminated disease. Molecular imaging techniques are playing an increasing role in early PCa detection, staging and disease recurrence. There are some molecular imaging modalities, radiotracers agents and its performance are important in current clinical practice PCa.

OBJECTIVE

This review summarizes the latest information regarding molecular imaging of PCa and is designed to assist urologists with ordering and interpreting these modalities and different radiotracers for different patients.

EVIDENCE ACQUISITION

A PubMed-based literature search was conducted up to September 2019. We selected the most recent and relevant original articles, metanalysis and reviews that have provided relevant information to guide molecular imaging modalities and radiotracers use.

EVIDENCE SYNTHESIS

In this review, we discuss 3 main molecular imaging modalities and 7 radiotracer technologies available.

CONCLUSIONS

The use molecular imaging modalities and radiotracers has a unique role in biochemical recurrence and diagnosis of ganglionar and bone progression of PCa. In the present time, no one of these molecular imaging modalities can be recommended over the classical work-up of abdominopelvic CT scan and bone scan, and large-scale and multi-institutional studies are required to validate the efficacy and cost utility of these new technologies.

The effect of androgen deprivation therapy on 68Ga-PSMA tracer uptake in non-metastatic prostate cancer patients

PURPOSE

To evaluate the effect of neoadjuvant androgen deprivation treatment (ADT) on prostate-specific membrane antigen (PSMA) tracer uptake demonstrated in ⁶⁸Ga-PSMA-positron emission tomography (PET/CT) in non-metastatic hormone-naïve prostate cancer (PC) patients.

MATERIALS AND METHODS

The clinical data of 108 PC patients who received neoadjuvant ADT were retrospectively analyzed. All patients had a baseline ⁶⁸Ga-PSMA-PET/CT scan, and a second scan was delivered median of 2.9 months after the initiation of ADT. The maximum standardized uptake value (SUV_max) of primary tumor (SUV_p) and metastatic lymph nodes (SUV_ln) as well as PSA response were assessed between pre- and post-ADT ⁶⁸Ga-PSMA-PET/CT scans.

RESULTS

There were significant decreases in posttreatment serum PSA, SUV_p, and SUV_ln. A decrease in SUV_p was seen in 91 patients (84%) with a median value of 66% (range, 5-100%), while 17 patients (16%) had no change in or an increase in PSMA tracer uptake with a median value of 24% (range, 0-198%). Patients with Gleason score (GS) of 7 had significantly higher metabolic response rates compared to other patients. The disease progression was significantly higher only in patients with GS > 7 disease compared to GS 7 disease. The PSA response to ADT was the lowest in patients with ISUP high-grade tumors. A total of 16 patients (15%) had progressive disease, and in 9 patients (8%), radiotherapy decisions were modified according to posttreatment ⁶⁸Ga-PSMA-PET/CT scans.

CONCLUSIONS

The current study includes the largest number of patients analyzed to date and demonstrates that ADT causes a significant decrease in serum PSA values and SUV_p and SUV_ln. The authors demonstrate that ⁶⁸Ga-PSMA-PET/CT may be used as a quantitative imaging modality after neoadjuvant ADT in hormone-naïve non-metastatic PC patients.

Incidental Finding of Intrathyroid Metastases of Prostatic Cancer on 18F-Choline PET/CT

An 85-year-old man with a 2-year history of prostate cancer, treated with radiotherapy and hormonal therapy, presented increased prostatic-specific antigen levels. F-choline PET/CT showed focal prostatic uptake consistent with known local recurrence, increased uptake of 2 hypodense thyroid nodules and of 2 left cervical lymph nodes, suspected as thyroid cancer. Neck ultrasound confirmed the high risk of malignancy, and a guided biopsy (of a thyroid nodule and cervical lymph node) revealed cellular infiltrates thyroid transcription factor-1 (TTF-1) negative and prostatic-specific antigen positive, confirming intrathyroid and cervical lymph node metastases of prostate cancer. PET/CT changed the disease staging. Chemotherapy was initiated.

18F-fluorocholine PET/CT in patients with occult biochemical recurrence of prostate cancer: Detection rate, impact on management and adequacy of impact. A prospective multicentre study

Aim

To prospectively evaluate the clinical impact and the diagnostic performance of FCH-PET/CT in patients with occult biochemical recurrence of prostate cancer (PCa).

Materials and methods

Results of 179 patients (mean PSA = 7.5ng/mL) with negative/inconclusive results of pelvic-MRI and of bone-scintigraphy were analysed. To determine the impact of FCH-PET/CT on diagnostic thinking and on patient management, the referring physicians prospectively filled-in a 1^st and 2^nd questionnaire related to patient’s planned management before and after FCH-PET/CT. Based on data from a 6-month follow-up after FCH-PET/CT, an independent assessor blinded to results of FCH-PET/CT determined the adequacy of management changes motivated by FCH-PET/CT.

Results

FCH-PET/CT localised foci evocative of recurrent PCa in 59% (105/179) of patients. Results of FCH-PET/CT motivated a change in scheduled patient management in 56% (100/179) of patients; which was considered as adequate in 89% (89/100) of patients. FCH-PET/CT also led to the detection of lung cancer in two patients.

Conclusion

FCH PET/CT is a powerful tool to localise the sites of occult biochemical recurrence of PCa, leading to an adequate management change in half of patients.

Oligometastatic recurrent prostate cancer detects by fluorine-18-choline positron emission tomography/computed tomography in patients with prostate-specific antigen levels of up to 5 ng/ml

PURPOSE

The aim of this study was to assess the ability of fluorine-18-fluorocholine (F-FCH) PET/computed tomography (CT) to detect oligometastatic disease (OMD) in patients with early recurrence of prostate cancer (PC) [prostate-specific antigen (PSA)≤5 ng/ml].

PATIENTS AND METHODS

Between 2010 and 2016, 324 patients with PC and PSA levels of less than or equal to 5 ng/ml were recruited. The mean (SD) age of the patients was 71 (10) years. All patients were treated with a radical prostatectomy±lymphadenectomy. One-hundred and twenty-one patients were under hormonal therapy at the time of PET/CT, whereas 203 were not. The mean (SD) PSA at the time of PET/CT was 1.33 (1.19) ng/ml, the mean (SD) PSA doubling time (PSAdt) was 10 (12) months, and the mean (SD) PSA velocity (PSAvel) was 1.94 (3.31) ng/ml/year. The correlation between continuous and categorical data was assessed using Student's t-test or by analysis of variance and by the χ-test, respectively. Univariate and multivariate analysis was carried out for the identification of clinical variables able to predict the presence of OMD.

RESULTS

One-hundred and ninety-three patients had a negative F-FCH PET/CT, whereas 131 (40.4%) had a positive scan. Of these latter patients, 35 had a significant F-FCH uptake in the prostatic fossae, 59 in the lymph nodes, and 37 in bone. PSA levels were significantly different between patients with a positive than those with a negative scan (P<0.001). F-FCH PET/CT was negative in the majority of patients with a PSA of less than or equal to 1 (63.2%) ng/ml. More than 60% of patients with a PSAdt of less than or equal to 6 months had a positive F-FCH PET/CT scan for OMD. PSAvel was higher in patients with a positive scan than those with a negative finding. At univariate analysis, PSA level, PSAdt, and PSAvel were predictors of a positive F-FCH PET/CT for OMD, whereas on multivariate analysis, only PSA level and PSAdt were independent predictors (both P<0.01). Furthermore, PSAdt was the only independent predictor of OMD at the lymph node level.

CONCLUSION

In patients with early recurrence of PC, F-FCH PET/CT is able to detect OMD in 40% of cases. This finding has an important impact on the detection of PC recurrent lesions that could be treated by local therapy to achieve long-term survival or cure.

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

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

Imaging of Prostate Cancer Using 18F-Choline PET/Computed Tomography

¹⁸F-fluorocholine (FCH) PET/computed tomography (CT) is a valuable imaging modality in prostate cancer disease. Probably, its main role is restaging of patients with biochemical recurrence after radical prostatectomy or external beam radiotherapy. ¹⁸F-FCH PET/CT is strengthening its position in the initial staging, biopsy target definition, radiotherapy planning, and therapy monitoring. Gleason score and prostate-specific antigen value, doubling time, and velocity can influence positivity of ¹⁸F-FCH PET/CT. The influence of androgen deprivation therapy on choline uptake is not precisely clarified. Collaboration between nuclear medicine physicians, radiologists, urologists, oncologists, and radiotherapists is crucial to help patients with prostate cancer disease.

Initial single-centre Canadian experience with 18F-fluoromethylcholine positron emission tomography-computed tomography (18F-FCH PET/CT) for biochemical recurrence in prostate cancer patients initially treated with curative intent

INTRODUCTION

We sought to determine predictive factors (patient and prostate-specific antigen [PSA] characteristics) for 18F-fluoromethylcholine positron emission tomography-computed tomography (18F-FCH PET/CT) positivity in the context of biochemical recurrence after local treatment of prostate cancer (PCa) with curative intent.

METHODS

This is a retrospective study including 60 18F-FCH PET/CT scans of patients with biochemical recurrence after initial radical prostatectomy (RP), external beam radiation therapy (EBRT), or focal high-intensity focused ultrasound (HIFU) with curative intent. The results were compared to findings on magnetic resonance imaging (MRI), computed tomography (CT), bone scan (BS), and histological analysis when available. Univariate analysis was performed to correlate results with patient characteristics.

RESULTS

Thirty-eight (63.3%) scans were positive, 17 (28.3%) negative, and 5 (8.3%) equivocal. Of the positive scans, 16 demonstrated local recurrence, 12 regional/distant lymph nodes, five bone metastasis, and five local and distant recurrences. Among the 22 PET/CTs showing metastasis, conventional imaging was performed in 16 patients (72.7%). Of these, it demonstrated the lesion(s) found on PET/CT in eight patients (50.0%), was negative in seven (43.8%), and equivocal in one (6.3%). The trigger PSA (p=0.04), prostate-specific antigen velocity (PSAV) (p=0.03), and prostate-specific antigen doubling time (PSADT) (p=0.046) were significantly different when comparing positive and negative scans. Patients with positive scans were more likely to have received EBRT initially (odds ratio [OR] 11.0, 95% confidence interval [CI] 2.2-55.3). A trigger PSA of 2.6 ng/mL had a sensitivity of 84% and specificity of 65% for a positive scan. PET/CT changed the clinical management plan in 17 patients (28.3%).

CONCLUSIONS

18F-FCH PET/CT demonstrates a high detection rate for local and distant recurrences after localized PCa treatment. A trigger PSA above 2.6 ng/mL seems optimal for appropriate patient selection.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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