Ga-68 PSMA Research Articles

Imaging quality of an artificial intelligence denoising algorithm: validation in 68Ga PSMA-11 PET for patients with biochemical recurrence of prostate cancer

Background68 Ga-PSMA PET is the leading prostate cancer imaging technique, but the image quality remains noisy and could be further improved using an artificial intelligence-based denoising algorithm. To address this issue, we analyzed the overall quality of reprocessed images compared to standard reconstructions. We also analyzed the diagnostic performances of the different sequences and the impact of the algorithm on lesion intensity and background measures.MethodsWe retrospectively included 30 patients with biochemical recurrence of prostate cancer who had undergone 68 Ga-PSMA-11 PET-CT. We simulated images produced using only a quarter, half, three-quarters, or all of the acquired data material reprocessed using the SubtlePET® denoising algorithm. Three physicians with different levels of experience blindly analyzed every sequence and then used a 5-level Likert scale to assess the series. The binary criterion of lesion detectability was compared between series. We also compared lesion SUV, background uptake, and diagnostic performances of the series (sensitivity, specificity, accuracy).ResultsVPFX-derived series were classified differently but better than standard reconstructions (p < 0.001) using half the data. Q.Clear series were not classified differently using half the signal. Some series were noisy but had no significant effect on lesion detectability (p > 0.05). The SubtlePET® algorithm significantly decreased lesion SUV (p < 0.005) and increased liver background (p < 0.005) and had no substantial effect on the diagnostic performance of each reader.ConclusionWe show that the SubtlePET® can be used for 68 Ga-PSMA scans using half the signal with similar image quality to Q.Clear series and superior quality to VPFX series. However, it significantly modifies quantitative measurements and should not be used for comparative examinations if standard algorithm is applied during follow-up.

V10-06 INTRAOPERATIVE USE OF PET/CT SPECIMEN IMAGER TO GUIDE ROBOTIC RADICAL PROSTATECTOMY AND PELVIC LYMPH NODE DISSECTION

You have accessJournal of UrologyCME1 Apr 2023V10-06 INTRAOPERATIVE USE OF PET/CT SPECIMEN IMAGER TO GUIDE ROBOTIC RADICAL PROSTATECTOMY AND PELVIC LYMPH NODE DISSECTION Marco Oderda, Serena Grimaldi, Giorgio Calleris, Daniele D'Agate, Federico Lavagno, Alessandro Marquis, Giancarlo Marra, Desireé Deandreis, and Paolo Gontero Marco OderdaMarco Oderda More articles by this author , Serena GrimaldiSerena Grimaldi More articles by this author , Giorgio CallerisGiorgio Calleris More articles by this author , Daniele D'AgateDaniele D'Agate More articles by this author , Federico LavagnoFederico Lavagno More articles by this author , Alessandro MarquisAlessandro Marquis More articles by this author , Giancarlo MarraGiancarlo Marra More articles by this author , Desireé DeandreisDesireé Deandreis More articles by this author , and Paolo GonteroPaolo Gontero More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003328.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Today, PSMA is the most accurate radiopharmaceutical in PCa and it can be used as a tracer to identify PCa foci in resected specimens. To do so, a small, high-resolution PET/CT-imaging device (XEOS AURA®) was developed, with near five-fold optimization in spatial resolution as opposed to the standard clinical PET/CT devices. Aim of this feasibility study was to test the intraoperative use of this brand-new PET/CT specimen imager to guide robot-assisted radical prostatectomy (RARP) and pelvic lymph node dissection (PLND). METHODS: To date, we performed three cases of RARP and PLND with intraoperative use of XEOS AURA® specimen imager. All patients underwent preoperative staging with MRI and PSMA PET/CT. Surgeries were performed with Da Vinci Xi robot. During trocar placement, an intravenous injection of 68-Ga PSMA, 2 mBq/kg, was performed. Lymph nodes were immediately removed through the 12-mm assistant trocar and inserted into the specimen imager for analysis. After complete excision, the prostate was removed through a short Pfannestiel incision while maintaining CO2 insufflation, and analysed with the specimen imager to check for positive margins (PSM) before doing the urethra-vesical anastomosis. RESULTS: On average, the time required by XEOS AURA® to analyse each specimen was 12 minutes (SD 3). Total and positive nodal yield were 17.3 (5.8) and 0.3 (0.5 SD), respectively. PET/CT specimen imager showed a marked uptake for the only positive node retrieved, and a diffuse, weak uptake in several negative nodes. There was a good correspondence between marked uptake and node positivity, reflecting also preoperative PET/CT findings (Table 1). XEOS AURA® was useful to predict negative surgical margins, although in one locally advanced case this evaluation was uncertain. CONCLUSIONS: The use of PET/CT specimen imager is safe and feasible. The intraoperative knowledge of prostate cancer (PCa) location within lymph nodes or inside the prostate is essential to improve the oncological radicality of the procedure while safely pushing the boundaries of a hyper-conservative surgery. Source of Funding: University of Turin © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e927 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Marco Oderda More articles by this author Serena Grimaldi More articles by this author Giorgio Calleris More articles by this author Daniele D'Agate More articles by this author Federico Lavagno More articles by this author Alessandro Marquis More articles by this author Giancarlo Marra More articles by this author Desireé Deandreis More articles by this author Paolo Gontero More articles by this author Expand All Advertisement PDF downloadLoading ...

Performances of 68Ga-PSMA PET-CT compared to 18F-FDOPA PET-CT to discriminate inflammatory radiation related changes from early recurrences in Glioblastoma's patients: Preliminary analysis

Discriminating recurrence from post-radiation related modification in patients with glioblastomas still remains challenging with morphological and functional imaging. The purpose of this pilot study was to assess the feasibility of 68Ga-PSMA PET/CT in detecting early recurrence, by comparison with 18F-FDOPA PET/CT. This was a non-randomized, prospective, multicentric feasibility study. Patients followed up for glioblastomas, with a MRI performed since the end of the radiotherapy until 12 months of follow up after the end of radiotherapy, were referred for both 68Ga-PSMA and 18F-FDOPA PET-CT, whatever the conclusion of the MRI (post radiation modifications, relapse or doubtful MRI). Nine patients from 2 centers were included. They were referred for both PET/CT which were realized the same day with a 6 hours delay. SUVmax, lesion-to-striatum ratio (TBR), lesion-to-normal parenchyma ratio (TNR), and lesion-to-salivary glands ratio (TSGR) were calculated. Among our nine patients, five patients demonstrated good correlation between 18F-FDOPA and 68Ga-PSMA PECT/CT findings. For four of these five patients, both examinations were consistent with recurrence, better visualized with PSMA, thanks to a better lesion-to-background ratio. Examinations of the fifth patient were suggestive of post radiation related changes. It was better analyzed with PSMA which displays a very faint uptake compared to DOPA. Conversely, four of our nine patients showed conflicting results. A recurrence was not detected by the PSMA because of a previously introduced bevacizumab treatment (false negative). For another patient, both examinations were consistent with recurrence, but there was an uptake mismatch regarding suspected lesion sites. This highlights distinct pathophysiological processes. Eventually, two patients presented inconsistent examinations, one patient with post radiation related remodeling (DOPA + PSMA−) and one suspected of recurrence (DOPA + PSMA−). Investigations are ongoing to try to explain these findings. Despite some scarce discrepancies between 68Ga-PSMA and 18F-FDOPA examinations, and the small number of patients included, this pilot study highlights the potential role of 68Ga-PSMA in helping to discriminate post-radiation inflammatory related modifications from glioblastoma recurrence in patients whithout recent bevacizumab treatment. The discrepancies are probably related to not fully understood distinct pathophysiological processes. False positives and false negatives could be minimised by following certain rules before carrying out the examination. 68Ga PSMA PET/CT seems useful because of its excellent lesion to background ratio. In case of positive PSMA recurrence, 177Lu PSMA could be considered as a new therapeutic alternative. However, more powerful prospective studies are needed to validate these results.

Imaging quality of an AI denoising algorithm: Validation in 68Ga PSMA-11 PET of patients with biochemical recurrence of prostate cancer

Imaging quality of an AI denoising algorithm: Validation in 68Ga PSMA-11 PET of patients with biochemical recurrence of prostate cancer

External validation of a convolutional neural network for the automatic segmentation of intraprostatic tumor lesions on 68Ga-PSMA PET images.

State of the art artificial intelligence (AI) models have the potential to become a "one-stop shop" to improve diagnosis and prognosis in several oncological settings. The external validation of AI models on independent cohorts is essential to evaluate their generalization ability, hence their potential utility in clinical practice. In this study we tested on a large, separate cohort a recently proposed state-of-the-art convolutional neural network for the automatic segmentation of intraprostatic cancer lesions on PSMA PET images. Eighty-five biopsy proven prostate cancer patients who underwent 68Ga PSMA PET for staging purposes were enrolled in this study. Images were acquired with either fully hybrid PET/MRI (N = 46) or PET/CT (N = 39); all participants showed at least one intraprostatic pathological finding on PET images that was independently segmented by two Nuclear Medicine physicians. The trained model was available at https://gitlab.com/dejankostyszyn/prostate-gtv-segmentation and data processing has been done in agreement with the reference work. When compared to the manual contouring, the AI model yielded a median dice score = 0.74, therefore showing a moderately good performance. Results were robust to the modality used to acquire images (PET/CT or PET/MRI) and to the ground truth labels (no significant difference between the model's performance when compared to reader 1 or reader 2 manual contouring). In conclusion, this AI model could be used to automatically segment intraprostatic cancer lesions for research purposes, as instance to define the volume of interest for radiomics or deep learning analysis. However, more robust performance is needed for the generation of AI-based decision support technologies to be proposed in clinical practice.

Ga-68 PSMA-11 impacting prostate cancer management in a real-world setting: A pilot experience using the total-body PET/CT scanner.

62 Background: PET/CT using Ga-68 PSMA-11, which received FDA approval, can detect early biochemical recurrence of prostate cancer at greater sensitivity than conventional imaging, as well as more accurately clinical stage and impact treatment management, particularly vital for high-risk patients. We present our first experience with Ga-68 PSMA-11 PET/CT using the total-body PET/CT scanner (uExplorer). Methods: PET/CT imaging (1-bed acquisition of the entire body for 5 minutes) was performed on the uExplorer scanner 56-65 minutes after administering 150-200 MBq of Ga-68 PSMA-11 (Illucix) in 14 patients with prostate cancer at our clinic. The medical records of these patients were reviewed. Results: Of the 14 patients who underwent Ga-68 PSMA-11 total-body PET/CT, 6 had high risk, 6 had intermediate risk and 2 had low risk cancers. The scan was negative in 1 patient, whereas local recurrence and pelvic lymph nodes could be identified in the other patient with low-risk prostate cancer. The smallest size of the lymph node identified was 2 mm. All patients with intermediate and high-risk cancers had metastatic disease – 2 had metastases to the lymph nodes only. Of the 10 patients with widespread metastases to bones and lymph nodes, 4 had additional visceral metastases – in 3 patients to the lungs and in 1 to the liver. The line of management changed in 10/13 patients with a positive scan – 5 were treated with Lu-177 PSMA radioligand, 4 with chemotherapy and 1 with local irradiation. Conclusions: Our pilot experience is consistent with the clinical value of Ga-68 PSMA-11 PET/CT (Illucix) imaging to better inform patient management, in addition to demonstrating the role of rapid and high-resolution imaging with the total-body PET/CT scanner (uExplorer). With the availability of PSMA PET/CT, it should be considered the new standard of care for men who have prostate cancer for staging or localization of recurrence.

Cyclotron vs generator-produced 68Ga PSMA: a single-institution, prospective clinical trial

The clinical utility of gallium 68 (68Ga)-PSMA PET for the diagnosis and management of prostate cancer is driven in part by radioisotope availability and production costs. This study evaluates the equivalence between the two manufacturing processes for 68Ga-PSMA: 68Ga-PSMA-cyclotron (from a solid target) and 68Ga-PSMA-generator. A prospective, single-arm, single-institution non-randomized study was conducted where 16 patients with prostate adenocarcinoma underwent PET/CTs consecutively within 12 to 48 hours with each type of manufactured 68Ga-PSMA between December 2020 and June 2021. The intraclass correlation coefficients suggested acceptable reliability in all lesion parameters (ICC > 0.70). Bland-Altman analysis demonstrated acceptable bias levels for all lesion parameters. Thereby 68Ga-cyclotron (solid target) and 68Ga-generator production methods tagged to the same PSMA ligand resulted in scans which were deemed to be equivalent in detecting PSMA+ lesions in our study. As cyclotron-produced, solid- target 68Ga can be made in large (Ci) quantities, it is a promising tool for future application in 68Ga-PSMA PET scans with the potential to decrease radiotracer production costs and increase isotope availability.

Metabolic response after 68Ga-PSMA-PET/CT-directed IGRT/SBRT for oligometastases prostate cancer

BackgroundWe used 68Ga PSMA PET/CT in the current investigation to assess the metabolic response and local control of metastasis in patients with oligometastatic prostate cancer receiving SBRT.Materials and proceduresWe performed a retrospective evaluation of the medical data of all patients with oligometastatic prostate cancer who underwent stereotactic body radiation therapy (SBRT) between 2017 and 2021. Our analysis only included medical records of patients who had SBRT for oligometastatic prostate cancer and had pre and post-SBRT 68Ga PSMA PET/CT images. Patient-related (age), disease-related (Gleason score, location of metastases), and treatment-related (factors and outcomes) data were collected from the medical files.ResultsA total of 17 patients (28 lesions) with a median age of 69 years were included in the research. A median follow-up of 16.6 months was used (range 6–36 months). The median follow-up period for 68 Ga PSMA PET/CT was 8 months (the range was 5–24 months). The median pre-treatment PSA level was 1.7 ng/mL (range 0.39–18.3 ng/mL) compared to the post-treatment PSA nadir of 0.05 ng/mL (0.02–4.57). During the follow-up period, local control was 96%, and there was a link between PSMA avidity on PET. In the treated lesions, there were no recurrences. During follow-up, none of the patients experienced toxicities of grade 3 or above.ConclusionsSBRT is a highly successful and safe way of treating patients with oligometastatic prostate cancer. Additional research is needed to examine 68Ga PSMA PET/CT to assess further for demarcation and follow-up.

172P Impact on management of non-metastatic prostate cancer biochemical recurrence with use of 68Ga PET-PSMA PET/CT scans in single-institution experience

68-Ga PSMA PET/CT has become a new reference standard for prostate cancer (Pca) imaging beyond conventional techniques. This study aims to compare the role of 68-Ga PSMA PET/CT and conventional imaging for staging and re-staging in nonmetastatic Pca who have biochemical Recurrence and evaluate the impacts on management.

P069 - Identification of clinically significant recurrence patterns in biochemical recurrence after radical prostatectomy and first salvage treatment in patients with prostate cancer using Ga68 PSMA PET-CT

P069 - Identification of clinically significant recurrence patterns in biochemical recurrence after radical prostatectomy and first salvage treatment in patients with prostate cancer using Ga68 PSMA PET-CT

The Relationship between the SUVmax Value Obtained in Ga-68 PSMA PET/CT and Lactate Dehydrogenase and Alkaline Phosphatase in Prostate Cancer.

ALP and LDH are serum markers of prognostic importance in prostate cancer patients. PET/CT imaging with Ga-68 PSMA has played an important role in prostate cancer imaging in recent years. Our aim in this study was to evaluate the relationship and prognostic significance between SUVmax values obtained with Ga-68 PSMA PET/CT and LDH and ALP levels in prostate cancer patients. We retrospectively evaluated 61 prostate cancer patients who had Ga-68 PSMA PET/CT imaging and who did not have a prostatectomy between 2019 and 2020. PSA, ALP and LDH levels were measured in all patients before or after imaging within a maximum of 28 days. The median age of the patients included in this study was 73 (range: 57-89) and all 61 patients were prostatic adenocarcinoma. 50 (82%) of the patients had distant metastasis in Ga-68 PSMA PET/CT. There was a significant positive correlation between serum LDH and PSA levels. There was a positive correlation between serum ALP and PSA levels. A negative correlation was found between ALP levels and prostate SUVmax. While negative correlation was found between SUVmax and ALP levels, no correlation was found between LDH levels and SUVmax. High ALP levels were found to be related to metastasis rates and severity and high serum PSA levels.

Correlation of Target Volumes on Magnetic Resonance Imaging and Prostate-Specific Membrane Antigen Brain Scans in the Treatment Planning of Glioblastomas.

Imaging of gliomas/glioblastomas has always been challenging. Many magnetic resonance imaging (MRI) techniques are available for imaging glioblastomas. MRI cannot always differentiate tumor from nonspecific changes and postoperative changes in brain tissue. Among the new positron emission tomography-computed tomography (PET-CT) tracers, gallium-68 prostate-specific membrane antigen (Ga-68 PSMA-11 PET-CT) appears to be the most promising one. The absence of uptake by normal brain parenchyma leads to high tumor-to-background ratio leading to better visualization of the tumor. The aim of this study was to assess the correlation of target volumes on MRI and PSMA brain scans in the treatment planning of glioblastomas. Twenty-four patients in the age group of 5-75 years with histologically proven glioblastoma were included in the study following maximum safe resection. Simulation for treatment planning was done with Ga-68 PSMA PET-CT brain with IV iodine-based contrast. The pre- and postoperative MRI images were fused with PSMA simulation images. Gross tumor volumes (GTVs) contoured on T1-contrast MRI and on PSMA scans were compared. GTV contoured on MRI and PSMA brain scans showed complete overlap in 17 patients. In seven patients, the target volumes drawn on Ga-68 PSMA brain scans were slightly smaller than the target volumes drawn on MRI brain scans. This difference in volumes could be due to postoperative changes which showed enhancement on the MRI scan. Ga-68 PSMA PET-CT shows good correlation with MRI brain in the evaluation and RT planning in glioblastomas. Tumor necrosis and postoperative changes did not show PSMA uptake. Precise target delineation on PSMA PET-CT can potentially result in smaller and more accurate GTVs, which in turn would result in less RT-induced side effects.

Development and validation of a nomogram for predicting the likelihood of metastasis in prostate cancer patients undergoing Ga-68 PSMA PET/CT due to biochemical recurrence.

To develop a nomogram based on commonly used clinical data for predicting the likelihood of metastasis in gallium-68 prostate-specific membrane antigen PET/computed tomography (Ga-68 PSMA PET/CT) scans of prostate cancer patients with confirmed biochemical recurrence (BCR). One-hundred thirty-five ( n = 135) patients who underwent Ga-68 PSMA PET/CT due to BCR were included in the study. Predictors of metastasis in Ga-68 PSMA PET/CT were determined with multivariable logistic regression analysis. Coefficients derived from the regression model were used to develop a prediction nomogram. The performance of the prediction model was evaluated with receiver operating characteristic analysis. Internal validation was performed with 50 bootstrap resamples, and the nomogram's clinical benefit was assessed with decision curve analysis. Multivariable logistic regression analysis revealed that ISUP group, prostate-specific antigen (PSA) before PET and PSA doubling time were independent predictors of metastasis in Ga-68 PSMA PET/CT. A prediction nomogram was developed according to this model [the area under curve: 0.866; 95% confidence interval (CI), 0.788-0.944]. The best cutoff value of the nomogram-derived likelihood for predicting metastasis was 60%, with a bootstrap-corrected accuracy of 78.8%. An online version of the nomogram was implemented on pro-gram.nzm.co ( https://pro-gram.nzm.co ). The proposed nomogram provides a practical approach for predicting the likelihood of imaging-based metastasis according to Ga-68 PSMA PET/CT in patients with BCR, with results ≥60% being the most accurate cutoff for referring patients to Ga-68 PSMA PET/CT. If validated in a larger cohort, this tool can serve as a guide for the appropriate use of Ga-68 PSMA PET/CT.

Clinical impact of PSMA PET in patients with biochemically recurrent prostate cancer after locoregional definitive therapy.

e17009 Background: [68Ga]-PSMA-11 positron emission tomography (PSMA PET) detects sites of biochemically recurrent prostate cancer (BCR) at higher rates than conventional imaging. We hypothesized that PSMA PET would lead to high change in management (CIM) rates in this setting. Methods: We prospectively recruited patients (pts) with BCR, defined as confirmed PSA &gt; 0.2 ng/mL &gt; 6 weeks post-surgery or PSA ≥2 ng/mL above nadir post-radiation therapy, to undergo Ga-68 PSMA-11 PET. Some also had equivocal lesions on CT, MRI, bone scan, or fluciclovine PET obtained prior to PSMA PET. Pre-PET intended treatment, PSA (ng/mL), and PSA doubling time (PSAdt, months) from most recent 3 values were recorded prior to imaging. Post-PET treatment (intended or actual) was collected from medical record. CIM was categorized as major (change in or addition of treatment modality) vs minor (change within treatment modality, such as altered radiation field). Any lesion with uptake above blood pool was interpreted as positive for prostate cancer by an experienced PET reader (DLC). All values were represented as the median [interquartile range, IQR]. Kruskal Wallis analysis tested for significant differences among groups. Results: 44 pts with BCR age 71 [10] with Gleason scores (GS) at diagnosis of 6 (N = 2), 7 (N = 23), 8 (N = 5), and 9 (N = 13) enrolled, 14/44 with equivocal lesions on conventional imaging. 42 had post-PSMA PET treatment decisions available in medical records for CIM analysis. Time from PSA nadir to PSA at time of PSMA PET was 5 [7.25] months. PSMA PET was positive in 33 (8/33 with equivocal lesions on prior imaging; 7 local disease only; 11 regional nodal metastases, 2/11 also with local disease; and 15 with distant metastases, 4/15 also with local disease, 9/15 with regional nodal metastases), negative in 6, and equivocal in 5 pts. Of those with distant metastases, 8 had oligometastases, defined as 3 or fewer distinct sites (1 site = single nodal region or single bone lesion), 4 in bones and 4 in distant nodes. CIM rate was 71% (30/42) overall, 65.5% (16/29 major, 3/29 minor) in pts with BCR and negative conventional imaging; 84.6% (11/13, all major) in pts with equivocal lesions on conventional imaging. Of the patients with major CIM, a treatment modality was added in 21/27, modality switched in 3/27, and a modality removed in 3/27. PSA was significantly lower (p = 0.04) for those with negative or equivocal PSMA PET (0.5 [2.7]) than those with localized disease (4.1 [2.8]), regional nodal (1.1 [3.4]) or distant metastases (3.8 [5.3]), but not PSAdt (p = 0.2, negative/equivocal PET 5 [6.5], localized 15 [36], regional nodal metastases 11 [13], distant metastases 6 [6]). Conclusions: PSMA PET may impact decision making in pts with BCR after treatment of localized prostate cancer, particularly for those with equivocal findings on conventional imaging, regardless of clinical risk at diagnosis. Clinical trial information: NCT04777071.

Evaluation of the Relationship Between Prostate-Specific Antigen Levels, Gleason Scores, and 68Ga-PSMA PET/CT Scan Findings in Prostate Cancer Patients

Background: The use of 68-gallium prostatespecific membrane antigen positron emission tomography/computed tomography (68Ga-PSMAPET/CT) scan has recently received particular attention in the evaluation of prostate cancer patients. Objectives: The present study aimed to evaluate the relationship between the prostate-specific antigen (PSA) level, Gleason score, and 68Ga-PSMAPET/CT findings in prostate cancer patients. Patients and Methods: In this cross-sectional study, 80 male patients with a definitive diagnosis of prostate cancer, who were candidates for 68Ga-PSMA PET/CT scan for both initial staging and restaging, were included. Restaging indicated biochemical recurrence, which refers to a detectable level of PSA after being documented undetectable following a definitive primary treatment. All prostate cancer patients, who were not initially treated with a definitive therapy, were excluded from the study. A cutoff value ≥ 4 was considered significant for maximum standardized uptake value (SUVmax) to differentiate benign from malignant 68Ga-PSMA-avid lesions. Any 68Ga-PSMA uptake outside the prostate bed, especially in the lymph nodes, bones, and visceral organs, was considered metastatic. Results: Comparison of the PSA level between two subgroups with and without metastasis demonstrated a higher PSA level in patients with metastatic abdominal lymph nodes and a slightly higher PSA level in patients with metastatic pelvic lymph nodes. No significant correlation was found between the Gleason score and the total PSA. There was also no significant association between the level of PSA and the type of Lymph node involvement (single or multiple) in different involved areas. Besides, there was no significant correlation between the SUVmax and the level of PSA and the Gleason score in different involved areas. Conclusion: The SUVmax value in 68Ga PSMA PET/CT scan provides a reliable predictor for neither the grade of prostate cancer, nor the metastatic status associated with cancer progression. The measurement of total PSA may predict metastasis to the abdominal and pelvic lymph nodes caused by prostate cancer.

Role of 68Ga and 18F PSMA PET/CT and PET/MRI in biochemical recurrence of prostate cancer: a systematic review of prospective studies.

To systematically review the prospective literature on the role of 68Ga and 18F PSMA PET/CT and PET/MRI as a tool for functional imaging in prostate cancer biochemical recurrence (BCR), particularly with respect to detection efficacy and impact on management. We performed a systematic literature search using PubMed in July 2021, focusing on original prospective studies looking at PSMA PET/CT and PET/MRI in BCR. We included 20 prospective studies reporting on 68Ga and 18F PSMA PET/CT and PET/MRI. Pooled PSMA PET positivity was 66.6% out of 2110 patients. The only factor consistently reported as associated with PSMA PET positivity was PSA level at the time of the study. Analysis of PSMA PET positivity rates in differing PSA ranges confirmed increasing positivity with increasing PSA levels. No significant adverse reactions were reported in the 20 studies, but only 6 studies mentioned safety or adverse reactions. A major change of management occurred in 42.7% of all patients scanned with PSMA PET/CT and more specifically 63.2% of those patients positive on PSMA PET/CT. There are no long-term studies that prove a survival benefit from these changes in management. There is prospective evidence for efficacy of PSMA PET/CT and PET/MRI in localizing disease recurrence in BCR, which increases with increasing PSA level at the time of scanning. There are no reported significant adverse effects related to the PSMA PET ligands. There is evidence of major change in management but no evidence for whether this achieves any improvement in outcome.

99mTc-PSMA targeted robot-assisted radioguided surgery during radical prostatectomy and extended lymph node dissection of prostate cancer patients.

The feasibility of tracer production of 99mtechnetium (Tc)-prostate-specific membrane antigen (PSMA)-I&S sterile cold kit, imaging with single photon emission tomography/computed tomography (SPECT/CT), and 99mTc-PSMA-radioguided robot-assisted laparoscopic radical prostatectomy (99mTc-PSMA-RG-RALRP) technique for lymph node (LN) dissection of primary prostate cancer (PCa) patients were evaluated prospectively. Fifteen primary PCa patients with intermediate- or high-risk score according to D'Amico risk stratification who had PSMA receptor affinity with Ga-68 PSMA-11 PET/CT were enrolled. After 99mTc-PSMA-I&S injection and SPECT/CT imaging, 99mTc-PSMA-RG-RALRP with DaVinci XI robotic platform and laparoscopic gamma probe were performed. Radioactive rating of resected tissue was compared with post-operative histopathology. Physiological and pathological uptakes of organs and tissues for both imaging modalities were compared. Physiological radiotracer distribution was similar for both imaging modalities. PCa lesions were much more visible on PET/CT. Metastatic LNs could not be visualized with SPECT/CT. Eighteen of 297 totally dissected LNs were metastatic, which were exactly the same with per-operative probe counts with sensitivity, specificity, accuracy, and negative and positive predictive value of all 100%. The median follow-up was 23.5 ± 4.6months. tPSA reduction was > 98%. The 2.5years biochemical recurrence-free survival, PCa-specific treatment-free survival and overall survival rates were 86,7%, 66,7% and 100%, respectively. Tc-99m-PSMA-RG-RALRP is a promising technique for extended pelvic lymph node dissection (ePLND) during robotic surgery, which may shorten the operation time and reduce complication risks. If LN metastases is detected during surgery with PSMA-targeted probe, it may be an early indicator of PCa-spesific treatment planning. Tc-99m-PSMA-I&S SPECT/CT is not as successful as Ga-68 PSMA-11 PET/CT for diagnosis of primary PCA lesions or LN metastases.

The role of Ga68 PSMA PET/CT imaging in Lu177 PSMA treatment planning in metastatic castration-resistant prostate cancer.

Lutetium-177 (Lu177) prostate-specific membrane antigen (Lu177 PSMA) is a novel targeted treatment for patients with metastatic castration-resistant prostate cancer (CRPC). The purpose of the study was to determine the molecular volumetric Gallium-68 (Ga68) PSMA PET/CT parameters that can predict patients who will respond to treatment. These single-center retrospective data were obtained from metastatic CRPC patients receiving intravenous 6.0-8.5GBq Lu177 PSMA treatment every 6-8weeks for a maximum of 3-8 cycles, with baseline Ga68 PSMA PET/CT scan, clinical data, and information on treatment responses. All lesions were divided into two groups according to the increase and decrease in PSMA expression levels of 600 bone lesions and 85 lymph nodes that were compatible with metastasis of 23 patients after the treatment. The primary endpoint of our study was the evaluation of the relation between the baseline SUVmax, PSMA TV, TL PSMA values, and the treatment response of the two groups. The threshold values were determined for the parameters that had significant relations. In the present study, the prostate-specific antigen (PSA) response and treatment-induced toxicities were also evaluated as the secondary endpoint. It was found that SUVmax, PSMA TV, and TL PSMA values in bone metastases showed significant differences between the groups with decreased and increased PSMA expression levels after the treatment. The AUC value for SUVmax was significant (AUC = 0.677; p < 0.001). The cutoff value was > 10.50 (sensitivity = 91.8%, Specificity = 41.5%) for SUVmax, > 1.50 cm3 (sensitivity = 49.1%, specificity = 70%) for PSMA TV and > 8.50g (sensitivity = %60.9, specificity = %72.2) for TL PSMA. The median SUVmax value before the treatment in all metastatic lymph nodes was found to be 7.1 (5.4-12.4), and the median SUVmax after the treatment was 2.5 (1.6-12.1) (p < 0.001). It was shown in the present study that Lu177 PSMA treatment response may be higher in CRPC patients with metastatic bone lesion with high baseline PSMA expression level, and better treatment response may be achieved in patients with lymph node metastases than in bone metastases.

68Ga-PSMA and 68Ga-DOTA-RM2 PET/MRI in Recurrent Prostate Cancer: Diagnostic Performance and Association with Clinical and Histopathological Data.

Simple SummaryProstate cancer (PCa) relapse occurs in up to 50% of patients after radical treatment. Once PCa recurrence is detected, a precise identification of the number and sites of recurrence is necessary to tailor the treatment on the patient’s needs. Positron emission tomography (PET) plays a pivotal role in this clinical setting and new radiotracers have been developed to improve its performance. While 68Ga-PSMA is a well-established radiotracer for PCa recurrence detection, 68Ga-DOTA-RM2 is a recently proposed tracer that targets the gastrin-releasing peptide receptors that are overexpressed in prostate cancer. In this work, the performance of 68Ga-PSMA and 68Ga-DOTA-RM2 PET/MRI in identifying recurrent disease were compared on the same cohort, using the same study protocol, as this is the only way to assess whether one outperforms the other and therefore should be preferred in clinical practice. Furthermore, the association between PET findings and clinical and histopathological characteristics was investigated to find potential biomarkers.The aim of the present study is to investigate and compare the performances of 68Ga-PSMA and 68Ga-DOTA-RM2 PET/MRI in identifying recurrent prostate cancer (PCa) after primary treatment and to explore the association of dual-tracer PET findings with clinical and histopathological characteristics. Thirty-five patients with biochemical relapse (BCR) of PCa underwent 68Ga PSMA PET/MRI for restaging purpose, with 31/35 also undergoing 68Ga-DOTA-RM2 PET/MRI scan within 16 days (mean: 3 days, range: 2–16 days). Qualitative and quantitative image analysis has been performed by comparing 68Ga-PSMA and 68Ga-DOTA-RM2 PET/MRI findings both on a patient and lesion basis. Clinical and instrumental follow-up was used to validate PET findings. Fisher’s exact test and Mann-Whitney U test were used to investigate the association between dual-tracer PET findings, clinical and histopathological data. p-value significance was defined below the 0.05 level. Patients’ mean age was 70 years (range: 49–84) and mean PSA at time of PET/MR scans was 1.88 ng/mL (range: 0.21–14.4). A higher detection rate was observed for 68Ga-PSMA PET/MRI, with more lesions being detected compared to 68Ga-DOTA-RM2 PET/MRI (26/35 patients, 95 lesions vs. 15/31 patients, 41 lesions; p = 0.016 and 0.002). 68Ga-PSMA and 68Ga-DOTA-RM2 PET/MRI findings were discordant in 11/31 patients; among these, 10 were 68Ga-PSMA positive (9/10 confirmed as true positive and 1/10 as false positive by follow-up examination). Patients with higher levels of PSA and shorter PSA doubling time (DT) presented more lesions on 68Ga-PSMA PET/MRI (p = 0.006 and 0.044), while no association was found between PET findings and Gleason score. 68Ga-PSMA has a higher detection rate than 68Ga-DOTA-RM2 in detecting PCa recurrence. The number of 68Ga-PSMA PET positive lesions is associated with higher levels of PSA and shorter PSA DT, thus representing potential prognostic factors.

The Relationship between the SUVmax Value Obtained in Ga-68 PSMA PET/CT and Lactate Dehydrogenase and Alkaline Phosphatase in Prostate Cancer

Objectives: ALP and LDH are serum markers of prognostic importance in prostate cancer patients. PET/CT imaging with Ga-68 PSMA has played an important role in prostate cancer imaging in recent years. Our aim in this study was to evaluate the relationship and prognostic significance between SUVmax values obtained with Ga-68 PSMA PET/CT and LDH and ALP levels in prostate cancer patients. Methods: We retrospectively evaluated 61 prostate cancer patients who had Ga-68 PSMA PET/CT imaging and who did not have a prostatectomy between 2019 and 2020. PSA, ALP and LDH levels were measured in all patients before or after imaging within a maximum of 28 days. Results: The median age of the patients included in this study was 73 (range: 57–89) and all 61 patients were prostatic adenocarcinoma. 50 (82%) of the patients had distant metastasis in Ga-68 PSMA PET/CT. There was a significant positive correlation between serum LDH and PSA levels. There was a positive correlation between serum ALP and PSA levels. A negative correlation was found between ALP levels and prostate SUVmax. Conclusions: While negative correlation was found between SUVmax and ALP levels, no correlation was found between LDH levels and SUVmax. High ALP levels were found to be related to metastasis rates and severity and high serum PSA levels.