Ga-68 PSMA Research Articles

Head-to-head comparison of GA-68 PSMA PET/CT and multiparametric MRI findings with postoperative results in preoperative locoregional staging and localization of prostate cancer.

Accurate staging of prostate cancer (PCa) is essential for determining the appropriate treatment and predicting outcomes. This study is comparing the effectiveness of Gallium-68 Prostate-Specific Membrane Antigen Positron Emission Tomography/Computed Tomography (Ga-68 PSMA PET/CT) and multiparametric MRI (mpMRI) in preoperative locoregional staging and localizing PCa. A retrospective analysis was conducted on 78 patients who underwent both mpMRI and Ga-68 PSMA PET/CT scans before surgery. The imaging was reviewed by radiologists and nuclear medicine specialists and compared with the final histopathology, which was reviewed by an experienced uropathologist. mpMRI demonstrated higher sensitivity in detecting extraprostatic extension (EPE) and bladder neck invasion (BNI) compared to Ga-68 PSMA PET/CT (83% vs. 44% and 29% vs. 17%, respectively). Conversely, Ga-68 PSMA PET/CT showed higher sensitivity in detecting seminal vesicle invasion (SVI) and lymph node metastasis (LNM) (75% vs. 55% and 50% vs. 30%, respectively). When both methods were combined, sensitivity increased in detecting both EPE and SVI. The index tumor localization in mpMRI and Ga-68 PSMA PET/CT was found to be in complete agreement with histopathological findings at 36.4% and 41.8%, respectively. When both imaging methods were combined, the agreement with histopathology in predicting index tumor localization reached 72.1%. Both mpMRI and Ga-68 PSMA PET/CT provide valuable and complementary information for tumor localization and locoregional staging. While mpMRI showed higher sensitivity in detecting EPE, Ga-68 PSMA PET/CT demonstrated superior performance in detecting LNM and SVI. The combined use of these imaging modalities enhance accuracy of index tumor localizations.

Time-efficient HPLC Validation Methodology for the Qualitative Analysis of 68Ga PSMA-11 in Routine Clinical Usage under Isocratic Method

Background: Prostate-specific membrane antigen (PSMA) has shown to be a promising agent for prostate cancer imaging under PET-CT. With the automation in radiolabeling with 68Ga, using iTG 68Ge/68Ga generator, it has helped introduce various new diagnostic agents and achieve good manufacturing practices (GMP) simultaneously. However, before any radiopharmaceutical is put into clinical usage, it should always be checked for its radiochemical purity and other quality parameters before injecting in the patient. Chromatography techniques such as Gas Chromatography (GC), High-Performance Liquid Chromatography (HPLC), and Thin-Layer Chromatography (TLC) are the most frequently utilized separation technique for purity analysis. A rapid quality control HPLC based methodology was required for radiopharmaceuticals. Aim & Objective: In our current setting, we conducted quality control analysis and standardized and validated HPLC method for the routine quality check of 68Ga-PSMA-11. Materials and Methods: The QC of 68Ga PSMA-11 was performed under ITLC and HPLC. Results: Linearity, accuracy, precision and specificity were assessed and quantified in accordance with International conference on harmonisation of technical requirements for registration of pharmaceuticals for human use (Q2 (R1) ICH) guidelines, which can be implemented in resource-limited settings to check the quality. Conclusion: The current HPLC based methodology is rapid, with a retention time of 2.24 min, rendering it a favorable analytical standard operating procedure for QC analysis of 68Ga-PSMA-11.

Baseline Ga-68 PSMA PET-Derived Primary Tumor Parameters in Patients with Prostate Cancer and Their Association with Clinical Risk Stratification and Clinicopathologic Features

Abstract Aim This article evaluates whether parameters derived from the gallium-68-labeled prostate-specific membrane antigen (68Ga-PSMA) positron emission tomography/computed tomography (PET/CT) imaging studies of primary prostate cancer (PCa) lesions were associated with Gleason score (GS), D'Amico risk class, Candiolo nomograms, and the metastatic status of the disease. Methods We retrospectively evaluated newly diagnosed PCa patients who underwent 68Ga-PSMA PET/CT before therapy. Age, baseline serum prostate-specific antigen (PSA), and metastatic status were recorded. Maximal standardized uptake value (SUVmax), mean SUV (SUVmean), total lesion PSMA (TL-PSMA), and PSMA-derived tumor volume (PSMA-TV) were analyzed. The patients were grouped according to GS (GS ≤ 7 and GS ≥ 8), D'Amico risk classes (low intermediate and high-risk), and also based on their results with the Candiolo nomogram which normally creates five risk classes. For Candiolo classes, very-low risk and low-risk patients were pooled into the low-risk Candiolo (LRC) group, high and very high-risk patients were pooled into the high-risk Candiolo (HRC) group. The intermediate-risk Candiolo group was utilized as-is (IRC). Results Mean age was 67 ± 8 years, median PSA value was 14.3 (3–211). There were 82 patients with GS ≤ 7 and 38 patients with GS ≥ 8; intermediate D'Amico class comprised 32 patients, while the high D'Amico class comprised 88 patients. For Candiolo, there were 23 LRC, 40 IRC, and 57 HRC patients. PSMA-positive metastases were detected in 44 (36.7%) patients. The SUVmean, SUVmax, PSMA-TV, and TL-PSMA values of the primary tumor demonstrated significant differences when compared according to classifications for GS, D'Amico, LRC versus HRC, and metastatic versus nonmetastatic patients. Of note, TL-PSMA was the only parameter that varied significantly among all risk groups. Conclusion Primary tumor parameters obtained from baseline 68Ga-PSMA PET/CT are useful to distinguish PCa patients in terms of GS, D'Amico, Candiolo nomogram, and metastatic states. TL-PSMA appears to be the best parameter as it is the only parameter that can distinguish all risk groups from each other.

Predictors of Metastasis in 68GA-Prostate Specific Membrane Antigen Pet-CT in the Primary Staging of Prostate Cancer.

Background: The objective of this study was to investigate factors influencing Gallium 68 Prostate Specific Membrane Antigen Positron Emission Tomography (Ga68 PSMA PET-CT) uptake for primary staging in prostate cancer. Methods: Retrospective analysis was conducted on 499 non-metastatic and 243 de novo metastatic prostate cancer cases undergoing Ga68 PSMA PET-CT. Demographic, clinical, and imaging data were collected and analyzed. Multivariate logistic regression determined independent risk factors for metastasis detection on Ga68 PSMA PET-CT. Results: Metastatic cases showed higher levels of total PSA, PSA density (dPSA) and biopsy ISUP grade group compared to non-metastatic cases. Multivariate analysis identified cT2 stage and dPSA as independent predictors of metastasis detection on Ga68 PSMA PET-CT. Conclusions: Ga68 PSMA PET-CT plays a crucial role in prostate cancer staging, with identified factors such as clinical T stage and dPSA significantly impacting its diagnostic accuracy. These findings underscore the importance of Ga68 PSMA PET-CT in refining clinical staging and guiding treatment decisions for prostate cancer patients.

An Analysis of the Diagnostic Performance of Tc-99m PSMA SSPECT/CT in Biochemically Recurrent Prostate Cancer Compared with Ga-68 PSMA PET/CT: A Single-center, Prospective Study.

Biochemical recurrence (BCR) after initial management of Prostate Carcinoma (PC) is frequent. Subsequent interventions rely on disease burden and metastasis distribution. 68Ga prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) is an excellent imaging modality in BCR. However, 68Ga is radionuclide generator produced and has restricted availability. 99mTc-labeled PSMA could be a potential cost-effective alternative. We compared the performance of 99mTc-PSMA single-photon emission CT (SPECT)/CT and 68Ga-PSMA PET/CT in BCR with a serum prostate surface antigen (PSA) level of <20 ng/mL. The prospective study included 25 patients with BCR and at least one lesion on a 68Ga-PSMA PET/CT. All patients underwent 99 mTc-PSMA SPECT/CT, and disease distribution and metastatic burden were compared with 68Ga-PSMA PET/CT. The maximum standard uptake value (SUVmax) and the tumor-to-background ratio (TBR) were computed and analyzed. The mean age and serum PSA (SPSA) were 69.72 ± 6.69 years and 5.65 ± 6.07 ng/mL. Eleven patients (44%) had SPSA ≤2 ng/mL. Recurrent sites were noted in the prostate (19, 76%), prostatic bed (3, 12%), and pelvis lymph nodes (LNs) (13, 52%). Distant metastasis to bones (13, 52%), lungs (5, 20%), and retroperitoneal LNs (2, 8%) were noted. Both modalities were concordant for the recurrent disease at the prostate, prostatic bed, bone, and lung lesions. 99mTc-PSMA could localize pelvis LNs in most patients (10/13, 76.9%). The site-specific sensitivity and specificity between the two modalities were not significantly different (P > 0.05). TBR shows excellent correlation with SUVmax (0.783, P < 0.001). Four (16%) patients were understaged with 99mTc-PSMA due to the nonvisualization of the subcentimeter size LNs. No patient with systemic metastases was understaged. 99mTc-PSMA SPECT/CT has good concordance with 68Ga-PSMA PET/CT in BCR, even at low PSA levels. However, it may miss a few subcentimeter LNs due to lower resolution. 99mTc-PSMA SPECT/CT could be a simple, cost-effective, and readily available imaging alternative to PET/CT.

Comparison of Ga-68 PSMA PET/CT and Multiparametric MRI for Initial Detection and Staging of Prostate Cancer

Abstract Background Multiparametric magnetic resonance imaging (mpMRI) is widely used for the evaluation of prostate cancer and is known to have better accuracy. Gallium-68 prostate-specific membrane antigen (Ga-68 PSMA) is a radiotracer that shows high localization in prostate cancer cells. Purpose The purpose of this study was to assess the sensitivity and utility of Ga-68 PSMA positron emission tomography/computed tomography (PET/CT) in comparison with mpMRI as a noninvasive imaging technique for the initial diagnosis and locoregional staging of prostate cancer using transrectal ultrasound (TRUS)-guided biopsy as gold standard. Materials and Methods This prospective observational study conducted from August 2017 to April 2020 evaluated 60 men (n = 60) with biopsy-proven prostate carcinoma. They underwent mpMRI and Ga-68 PSMA PET/CT scans within 14 days with TRUS biopsy being gold standard. T staging of disease, N staging of lymph nodes within the pelvis, and M staging of lesions in pelvic bones (within the imaging field of mpMRI) were compared using PSPP version 1.0.1 statistical software. Results All 60 men with a mean age of 69.9 ± 9.35 years showed Ga-68 PSMA avid disease, whereas 55 were detected by mpMRI. The sensitivity in detection of prostate lesions (with 95% confidence interval) was 99.08% for Ga-68 PSMA PET/CT and 84.40% for mpMRI. Ga-68 PSMA PET/CT detected greater number of patients with regional lymph nodal involvement (19/60) as compared with mpMRI (12/60). Ga-68 PSMA PET/CT showed PSMA avid pelvic skeletal lesions in nine patients, whereas mpMRI detected pelvic lesions in six patients. In addition, four other patients showed extrapelvic skeletal lesions on Ga-68 PSMA PET/CT. Conclusion Ga-68 PSMA PET/CT has superior sensitivity in detection of primary prostate tumor, as compared with mpMRI. Both modalities correlate well in detection of seminal vesicle involvement. Ga-68 PSMA PET/CT outperformed mpMRI in detection of lymph nodal and skeletal metastases. Hence, Ga-68 PSMA PET/CT should be considered as first-line diagnostic modality for carcinoma prostate. Summary Statement: Ga-68 PSMA PET/CT shows superior diagnostic performance than mpMRI in the evaluation of prostate cancer.

Diagnostic Accuracy of a Combination of Preoperative 68-Ga Prostate-Specific Membrane Antigen Positron Emission Tomography/Computed Tomography and Multiparametric Magnetic Resonance Imaging in Localized Prostate Cancer

Introduction: Prostate cancer (PCa) is a common and leading course of cancer-related death in men. Although there are studies on multiparametric magnetic resonance imaging (MpMRI) with good diagnostic results in detecting clinically significant PCa, new methods have been investigated due to the low positive predictive values. In this context, prostate-specific membrane antigen positron emission tomography (PSMA PET) emerges as an alternative imaging method to MpMRI. This study aimed to compare 68Ga PSMA I&T-PET/CT and MpMRI in determining tumor location. Methods: Preoperative MpMRI and 68Ga PSMA I&T-PET/CT scans and pathology specimens of patients who underwent radical prostatectomy for PCa at our clinic between 2018 and 2021 were retrospectively evaluated. PSMA I&T-PET/CT, MpMRI, combined imaging were compared for tumor localization according to histopathological data. Results: In terms of tumor localization, MpMRI demonstrated overall accuracy rates of 75.9% (p kappa [κ] 0.0001* [0.525]). 68Ga PSMA I&T-PET/CT showed 71.5% (p κ 0.0001* [0.438]). For the combined imaging approach, the overall accuracy rate was calculated as 79.2% (p κ 0.0001* [0.576]). Additionally, high diagnostic accuracy was achieved for the combined imaging approach, particularly in the intermediate ISUP group. Moreover, SUVmax was calculated as 6.37. Conclusion: The combined use of 68Ga PSMA I&T-PET/CT and MpMRI has high diagnostic rates. However, the high cost is a significant disadvantage that limits their routine combined use.

Patient-Derived Tumor Xenograft Study with CDK4/6 Inhibitor Plus AKT Inhibitor for the Management of Metastatic Castration-Resistant Prostate Cancer.

Metastatic castration-resistant prostate cancer (mCRPC) is an aggressive malignancy with poor outcomes. To investigate novel therapeutic strategies, we characterized three new metastatic prostate cancer patient derived-tumor xenograft (PDTX) models and developed 3D spheroids from each to investigate molecular targeted therapy combinations including CDK4/6 inhibitors (CDK4/6i) with AKT inhibitors (ATKi). Metastatic prostate cancer tissue was collected and three PDTX models were established and characterized using whole-exome sequencing. PDTX 3D spheroids were developed from these three PDTXs to show resistance patterns and test novel molecular-targeted therapies. CDK4/6i's were combined with AKTi's to assess synergistic antitumor response to prove our hypothesis that blockade of AKT overcomes drug resistance to CDK4/6i. This combination was evaluated in PDTX three-dimensional (3D) spheroids and in vivo experiments with responses measured by tumor volumes, PSA, and Ga-68 PSMA-11 PET-CT imaging. We demonstrated CDK4/6i's with AKTi's possess synergistic antitumor activity in three mCRPC PDTX models. These models have multiple unique pathogenic and deleterious genomic alterations with resistance to single-agent CDK4/6i's. Despite this, combination therapy with AKTi's was able to overcome resistance mechanisms. The IHC and Western blot analysis confirmed on target effects, whereas tumor volume, serum PSA ELISA, and radionuclide imaging demonstrated response to therapy with statistically significant SUV differences seen with Ga-68 PSMA-11 PET-CT. These preclinical data demonstrating antitumor synergy by overcoming single-agent CDK 4/6i as well as AKTi drug resistance provide the rational for a clinical trial combining a CDK4/6i with an AKTi in patients with mCRPC whose tumor expresses wild-type retinoblastoma 1.

Prognostic value of artificial intelligence (AI) –driven tumor estimation of PSMA PET total tumor burden (TTB) in newly diagnosed high-volume metastatic hormone-sensitive prostate cancer (mHSPC).

47 Background: Prostate cancer represents a significant economic burden for health systems; the identification of risk factors that allows the identification of subgroups of patients that require closer follow-up or more intense therapeutic regimens has a direct impact on the prognosis and expenses for the patient, there is currently great interest in patients with high-volume mHSPC, this group is defined according to the number of lesions and their location, this could represent a challenge in decision making due to the variety of presentations regarding tumor burden, currently with the development of AI algorithms it is possible to estimate the PSMA TTB by identifying patients who are candidates for specific therapies without exposing them to comorbidities associated to aggressive regimens. Methods: Baseline PSMA PET scans of patients with histopathological corroborated diagnosis of prostate cancer and considered as high volume according to 68Ga PSMA PET/CT imaging in the period from October 2017 to June 2020 were retrospectively analyzed using an automated algorithm to estimate PSMA TTB, the median follow-up was of 44 +/- 9.7 months. These patients were divided into two groups according to the optimal cutoff values of PSMA TTB and estimate progression-free survival after initial therapy with Kaplan-Meier curves and correlation index between tumor burden and prostatic specific antigen. Results: 53 patients with a mean age of 71 years (+/- 5.1) were included, 17 with Gleason 7 (4+3/3+4), 18; G8 (4+4), 15; G9 (5+4/4+5) and 3; G10 (5+5), ISUP group 3 (n=17), group 4 (n=18) group 5 (n=18), the mean PSA value at diagnosis was 62.1 ng/dL (range 25.2- 201.5). PSMA TTB mean was 100.1cm3 (range 21cm3- 518.8 cm3). Log-rank test revealed that PSMA TTB lower than 45 cm3 (n=21) presented higher time of progression-free survival in comparison with patients with PSMA TTB higher than 45 cm3 (n=32) (31.1 mo vs 47.8 mo, p &lt;0.003). TTB and PSA demonstrated a significant correlation (Pearson r= 0.526, p&lt; 0.0001). There was no difference between groups of low and high PSMA TTB and ISUP groups or Gleason score. Sites of visceral disease were lung (n=11), (pleura=9) liver (n=9), adrenal, (n=5) brain, (n=2), and sites of extra spinal and pelvic disease were ribs (n=24) femur (n=16), skull (n=8), scapula (n=7), humerus (n=7). All patients had one or more lesions at previously described sites. Conclusions: PSMA TTB has great value in predicting progression-free survival of patients with newly diagnosed high-volume metastatic hormone-sensitive prostate cancer and has a strong correlation with PSA, strengthening the role of next-generation molecular imaging with PSMA PET as an invaluable tool in initial diagnosis and potentially in follow-up by providing information on the biological behavior of the disease in a systemic way.

Convoluted Neural Network for Detection of Clinically Significant Prostate Cancer on 68Ga PSMA PET/CT Delayed Imaging by Analyzing Radiomic Features.

To assess the utility of convoluted neural network (CNN) in differentiating clinically significant and insignificant prostate cancer in patients with 68Ga PSMA PET/CT-targeted prostate biopsy-proven prostate cancer. In this retrospective study, 142 patients with clinical suspicion of prostate cancer were evaluated who underwent 68Ga-PSMA PET/CT imaging followed by 68Ga-PSMA PET/CT-targeted prostate biopsy from the PSMA-avid prostate lesion. Twenty patients with no PSMA-avid lesions were excluded. Local Image Features Extraction (LifeX) software was used to extract radiomic features (RF) from delayed 68Ga-PSMA PET/CT images of 122 patients. LifeX failed to extract radiomic features in 24 patients, and the remaining 98 were evaluated. RFs were fed to an in-built CNN of the software for computation and results were achieved. Patients with Gleason Score ≥ 7 on histopathology were labeled clinically significant prostate cancer (csPCa). The diagnostic values of radiomic features were evaluated. The csPCa was revealed in 69/98 (70.4%) patients, and insignificant PCa was noticed in 29/98 (29.6%) patients. The software extracted 124 RF from the delayed 68Ga-PSMA PET/CT images. The accuracy of the CNN was 80.7% to differentiate clinically significant and clinically insignificant prostate cancer, with an error percentage (E %) of 19.3%. The sensitivity, specificity, positive predictive, and negative predictive values were 90.3%, 57.7%, 83.6%, and 71.4%, respectively, to detect csPCa. CNN is a feasible pre-biopsy screening tool for identifying clinically significant prostate cancer and can be used as an adjunct in the initial diagnosis and early treatment planning. The online version contains supplementary material available at 10.1007/s13139-023-00832-3.

Diagnostic accuracy of bone scan at different PSA levels in biochemical recurrence of prostate cancer

ObjectiveTo determine the diagnostic accuracy of Bone Scan at different PSA levels for detecting skeletal metastases in men with biochemical recurrence of prostate cancer. MethodsWe conducted a retrospective review of the statewide RIS-PACS to identify 251 men with biochemical recurrence who underwent both a Bone Scan and Ga68 PSMA PET/CT (within 2 months of each other) between September 2019 and December 2022 at a single institution. The Ga68 PSMA PET/CT report was considered to be the reference standard. ResultsThe median age was 72 years (IQR 67–76) with a median PSA level of 1 ng/ml (IQR 0.25–2.8). Using Ga68 PSMA PET/CT as the reference standard, 68/251 patients (25%) were positive for osseus metastases. Overall sensitivity and specificity of Bone Scan was 51% (95% CI 40–64%) and 99% (95% CI 98–100%) respectively. Using PSA banding, a PSA threshold of 20 ng/ml provided the greatest discriminatory benefit with sensitivity of the Bone Scan below the threshold being 46% (95% CI 33–59%) and above the threshold being 89% (95% CI 68–100%). Specificity remained consistently high both below and above this threshold. ConclusionBone Scan provides greater diagnostic accuracy for detecting skeletal metastases in biochemical recurrence when the PSA level is above 20 ng/ml. This knowledge is valuable in optimising imaging algorithms in biochemical recurrence, particularly in regions where PSMA PET/CT is less readily available or affordable.

Evaluation of Gallium-68 prostate-specific membrane antigen, positron emission tomography/computed tomography (GA-68 PSMA PET/CT) in recurrent prostate cancer: a retrospective review of initial clinical experience at Tygerberg Hospital.

prostate cancer recurrence after definitive therapy for organ-confined disease often manifests as rising prostate-specific antigen (PSA) levels without clinically overt disease. 68Gallium prostate-specific membrane antigen, positron emission tomography/computed tomography (68GaPSMA PET/CT) imaging plays a major role in the management of recurrent prostate cancer. The purpose of this study was to assess the positivity rate of 68Ga PSMA PET/CT scans in cases of prostate cancer recurrence, and to compare the results with existing international literature. a retrospective analysis of 177 68Ga PSMA PET/CT scans of patients with biochemically proven disease recurrence was performed. The possible association of a positive PSMA PET/CT with the PSA level and Gleason score were analyzed. a total of 177 68Ga PSMA PET/CT scans were performed in 163 patients (median age 66 years). Of these, 117 (66%) scans detected the site of disease recurrence. Among patients with PSA 0.2-0.99 ng/ml, 23/49 (47%, p<0.0001) were positive, and 20/35 (57%, p<0.0005) were positive in the group of patients with PSA 1.00-1.99. When PSA values were further categorized into PSA <2 ng/ml and PSA ≥2 ng/ml, detection rates were 49% and 86% respectively (p <0.0001). The scans were positive in 65% of patients with Gleason score of <7, 62% with Gleason score of =7 and 68% with Gleason score >7 (p=0.745). there was an increase in the detection rate with an increase in the PSA. Gleason score was not a predictor of a positive 68Ga PSMA PET/CT scan. 68Ga-PSMA PET/CT should be prioritized in patients with biochemical recurrence with PSA levels >0.2 ng/ml.

Formulating a national position statement and guide on modern theranostics in the Philippines.

Barriers to the establishment of advanced technologies in developing countries were overcome when modern theranostics pertaining to the use of Ga-68 and Lu-177 PSMA and DOTATATE were first offered to patients in the Philippines in early 2018. However, significant growth was not experienced at St. Luke's Medical Center for five years and lutetium was not yet distributed to other institutions by a radiopharmaceutical supplier. Due to the relative novelty and rapid expansion of theranostics worldwide, position statements were released by the Australasian Association of Nuclear Medicine Specialists, European Association of Nuclear Medicine, Society of Nuclear Medicine and Molecular Imaging, and International Atomic Energy Agency primarily to uphold patient safety and ensure a level of standard among its practitioners. Subsequently in the latter half of 2022, these were adopted and modified according to what is feasible and applicable locally within the Philippine Society of Nuclear Medicine, considering the current status and future possibilities. Different representatives were involved, and several groups were mobilized for successful implementation. A liability clause was incorporated to discourage unprofessional acts.

Rational use of Ga-68 PSMA PET-CT according to nomograms and risk groups for the detection of lymph node metastasis in prostate cancer

ObjectivesThe aim was to ensure efficient utilization of PSMA PET-CT by examining the correlation of pathological lymph node metastasis with nomogram scores and risk classifications. Methods and materialsRobot-assisted radical prostatectomy and bilateral pelvic lymph node dissections for pelvic lymph nodes were performed using the same template. Bilaterally pelvic lymph nodes were removed within the boundaries of genitofemoral nerves, psoas muscle and lateral pelvic wall laterally, ureteric crossing of the iliac vessels superiorly, lateral bladder wall medially, Cooper ligaments distally, and endopelvic fascia, neurovascular bundles and internal iliac arteries posteriorly. Clinical nomograms were used to calculate the probability of lymph node metastasis preoperatively. Using receiver operating characteristics analysis, discriminatory cut-offs were calculated. The diagnostic performance of PSMA PET-CT was determined for detecting lymph node metastasis. ResultsFor 81 patients, the median age was 64 years. The median PSA was 6.8 ng/ml. Most patients were in the D'Amico intermediate (56.8%) and high (37%) risk groups. Median Briganti 2017, MSKCC, and Partin scores were 35 (4–99), 37 (8–90), and 12 (2–38), respectively, in pN1 patients. The area under the curve for Briganti 2017, MSKCC, Partin nomograms and PSMA PET-CT scans were 0.852, 0.871, 0.862, and 0.588. Sensitivity, specificity, positive predictive value and negative predictive value for Ga-68 PSMA PET-CT for lymph node metastasis detection were 21.4%, 94%, 42.9%, and 85.1%, respectively, for the whole group. By using higher threshold values for clinical nomograms (Briganti 2017 >32, MSKCC >12, Partin >5), PSMA PET-CT had higher sensitivity (42.9, 30, 27.2) in detecting lymph node metastasis. ConclusionsPatients in the D'Amico high-risk group and those with high nomogram scores are the best candidates who will benefit from preoperative PSMA PET-CT staging to estimate lymph node metastasis.

Enhancing PSMA PET/CT imaging of prostate cancer: investigating the impact of multiple time point evaluation, diuretic administration, cribriform pattern, and intraductal carcinoma.

Our objective was to correlate staging PSMA PET imaging parameters to final histopathology. Second objective was to assess the performance of standard versus delayed PSMA PET to detect primary prostate tumor. Thirty-one patients (mean age, 61.4 ± 8.2) who underwent radical prostatectomy and preoperative staging PSMA PET scans were included in the study. After defining dominant lesion in pathology, correlations with PET images were performed. Additionally, two physicians blind to clinical and pathological information retrospectively reviewed staging Ga-68 PSMA PET scans with standard and delayed imaging. Dominant lesion SUV's increased with time 8.2(± 4.5), 10(± 7.1), and 10.2(± 7.8) at 1, 2, and 3h (P = .03 T1-T3). WHO Grade group 3 had highest SUV (group 3 11.9 ± 5.6 vs. group 2 7.9 ± 1.5, p = .02). Addition of cribriform pattern on intraductal component was associated with higher SUV's (11 ± 2.9 vs. 6.5 ± 2.1, p = .01) and higher Gleason four ratios (64 ± 9% vs. 37 ± 17%, p = .01). Intraductal carcinoma was associated with larger tumors (6.3 ± 2.3cm3 vs. 2.6 ± 1.7cm3, p < .001). Physician sensitivities ranged from 61 to 81%. Excluding Gleason 3 + 3 lesions and small lesions (< 1cm3), sensitivities increased to 80-100%. Differences of sensitivity between different time points were not significant. Combined evaluation of all time points did not increase sensitivity. Cribriform pattern correlates with higher Gleason 4 ratios and SUVs in PSMA PET. Intraductal carcinoma is associated with larger tumors but not higher Gleason 4 ratios and SUVs. Multiple late imaging times did not enhance tumor detection and may pose tolerability issues for some patients.

Intraoperative Frozen Section via Neurosafe During Robotic Radical Prostatectomy in the Era of Preoperative Risk Stratifications and Primary Staging With mpMRI and PSMA-PET CT: Is There a Perfect Candidate?

We aimed to analyze the effect of preoperative risk assessment including Ga-68 PSMA PET and multiparametric magnetic resonance imaging (mpMRI) on nerve sparing practices, positive surgical margin (PSM) rates and oncological outcomes based on a comparison between patients underwent RARP with and without Neurosafe (NS). Patients underwent RARP with NS (RARP-NS) or without (RARP-only) NS retrospectively evaluated. Suspicion for extracapsular extension on mpMRI and/or Ga-68 PSMA PET was recorded as i(imaging)T3. NS was performed according to the Martini-Klinik technique. PSM at preserved bundle side were called PSM at region of interest (ROI) while the others were elsewhere. A total of 208 patients (90 in RARP-NS, 118 in RARP-only groups) were included. Preoperatively the RARP-only group showed significantly higher mean PSA (p=.01) and PIRADS 5 (p=.002) findings and had more D'Amico high risk (DAHR) patients (p=.08). The overall PSM rates for pT2 versus pT3 disease were 7.5% versus 21.6 and 15.6% versus 55% in RARP-NS and RARP-only groups, respectively. NS resulted in more bilaterally preserved bundles (81.1% vs. 66.3%) and less PSM at the ROI (3.3% vs. 23.4%) than RARP-only group. NS outperformed RARP-only in all clinical settings had its highest differential benefit in more bilateral nerve sparing and less PSM at ROI in patients with both DAHR and iT3 disease. BCR rates were 2.2% and 2.5% for RARP-NS and RARP only groups, respectively (p=.4). One patient in RARP-NS and 9 in RARP-only groups had PSA persistence (p=.02). RARP-NS led to more preserved bundles with less PSM. It was especially useful in DAHR patients with preoperative extracapsular extension suspicion in imaging simultaneously.

Poster 17 - The impact of Ga-68 PSMA PET CT scanning on change of treatment modalities for the management of recurrent prostate cancer, in an Irish cohort

Poster 17 - The impact of Ga-68 PSMA PET CT scanning on change of treatment modalities for the management of recurrent prostate cancer, in an Irish cohort

Role of 68Ga-PSMA PET/CT in Initial Staging of Prostate Cancer and Correlation with PSA and Gleason Score

Background Prostate cancer is the second most common male malignancy. Its prognosis depends on the tumor stage as well as its aggressiveness; expressed histopathologically by Gleason scores. Furthermore, optimal patient management depends on the tumor stage. 68Ga PSMA PET/CT has a wide spectrum of uses in prostate malignancy, some of them are comprehensively studied while others are still under investigation. The most widely accepted use is the accurate initial staging of cancer prostate as well as predicting the long-term outcome, with SUVmax being a promising prognostic parameter correlating significantly with other established prognostic parameters, including the Gleason score and the PSA levels. Objective To evaluate the role of 68GA- PSMA PET/CT in initial staging of prostate cancer and correlate with PSA level and Gleason score. Methods A prospective descriptive study over the course of 6 months. It included patients with pathologically proven prostate cancer referred for a PSMA PET/CT scan for initial staging without any treatment or interventions. Results 68Ga-PSMA PET/CT scans of 36 patients were evaluated for local staging (primary prostatic lesions, extra-prostatic spread, and seminal vesicle invasion), regional nodal staging, and metastatic spread (extra-regional lymph nodes, osseous lesions, and visceral lesions). PET/CT findings as well as the SUVmax of the most avid lesions were correlated with PSA level, Gleason scores, as well as Gleason grade risk groups. A statistically significant relationship was found between PSA level and SUVmax of prostatic lesion as well as that of the most avid metastatic regional lymph node, the presence of extra-regional lymph nodal spread, the presence of osseous metastatic lesions, the presence of seminal vesicle invasion, extra-prostatic extension, and the presence of PSMA-avid regional lymph nodal spread. On the other hand, a statistically significant relationship was found between Gleason scores and the presence of regional lymph nodal spread and osseous metastatic lesions. Lastly, a statistically significant relationship was found between Gleason grading risk groups and the presence of regional lymph nodal spread and osseous metastatic lesions. Conclusion 68Ga-PSMA PET/CT is a powerful staging and stratifying tool for the majority of prostate cancer patients, being significantly correlated with PSA level and Gleason scores. However, patients with low PSA scores still pose a dilemma as they showed significantly low PSMA uptake, rendering the use of 68Ga-PSMA PET/CT for staging in such patients controversial. 68Ga-PSMA PET/CT based imaging findings should ideally be supported with histopathological documentation and/or follow-up imaging results in order to confirm the nature of detected lesions and help establish accurate sensitivity and specificity of 68Ga-PSMA PET/CT.

Targeted Biopsy in Men High Risk for Prostate Cancer: 68Ga-PSMA PET/CT Versus mpMRI

Introduction/BackgroundTo evaluate the accuracy of 68Ga-PSMA PET/CT versus mpMRI targeted biopsy (TPBx) in the diagnosis of clinically significant prostate cancer (csPCa) in men high risk for PCa. Materials and MethodsFrom January 2021 to March 2023, 125 men with clinical parameters high risk for PCa were evaluated by mpMRI and 68Ga-PSMA PET/CT; median PSA was 32.5 ng/mL (range: 12-160 ng/mL) and 60/125 (48%) had abnormal digital rectal examination. The mpMRI lesions with PI-RADS scores ≥ 3 and/or 68Ga-PSMA areas characterized by a standardized uptake value (SUVmax) values ≥ 8 were submitted to TPBx (4 cores); in addition, all the patients underwent systematic transperineal prostate biopsy (18 cores) under sedation and antibiotic prophylaxis. ResultsIn 80 of 125 men (64%) a csPCa was found: 10 (12.5%) had a ISUP Grade Group 3 (GG), 45 (56.2%) a ISUP GG4 and 25 (31.2%) ISUP GG5. The median intraprostatic 68Ga-PSMA SUVmax was 42.3 (range:10.5-164) and 72 of 80 (90%) had a PI-RADS score ≥ 3. 68GaPSMA PET/CT showed the presence of metastases in 20 of 80 (25%) men: the median SUVmax in bone (15 cases) and nodes (40 cases) metastases was 55 and 47, respectively. Accuracy of 68Ga PSMA PET/CT (SUVmax cut-off ≥ 8) versus mpMRI PI-RADS score ≥ 3 in the diagnosis of csPCa was 92 versus 86.2%. Conclusion68GaPSMA PET/CT demonstrated a good diagnostic accuracy as a single procedure for the diagnosis and staging of high-risk PCa.

Retrospective review of 250 gallium-68 PSMA scans in prostate cancer patients in Health Canada Special Access Program.

e17035 Background: Prostate Cancer is the most common malignancy in men, and until recently has been staged using standard imaging tests, such as ultrasound, CT, bone scan, and MRI. A novel imaging test targeting the membrane receptor, Prostate Specific Membrane Antigen (PSMA) using the PET tracer Ga-68 PSMA-11 has recently been approved in several countries for staging and assessing potential for radionuclide therapy. This agent was only recently approved in Canada, but has been available through the Health Canada Special Access (SA) Program for over a year, until it was approved (Illuccix, Telix Pharmaceuticals). Methods: In the past year, 275 prostate cancer patients were scanned at our facility (INITIO Medical Imaging, Burnaby BC) through Health Canada SA. All patients were required to have positive prostate cancer biopsies, with negative or indeterminate CT and bone scan, and rising PSA (prostate specific antigen) blood test in order to qualify for SA, or high risk Gleason Score prostate cancer. Results: Of the 275 patients, 71 had high risk cancers and 28/71 had positive PSMA studies (39%). 185 of the patients had biochemical evidence of recurrence and negative /indeterminate conventional imaging tests, and 101/185 or 55% had positive PSMA scans. All other patients were scanned for metastatic castrate resistant prostate cancer (MCRPC). Conclusions: Ga-68 PSMA scans are highly sensitive for upstaging patients at high risk of prostate cancer metastasis or recurrence, even with negative conventional imaging studies.