68Ga Prostate-Specific Membrane Antigen Research Articles

Assessing ChatGPT's summarization of 68Ga PSMA PET/CT reports for patients.

ChatGPT has recently been the subject of many studies, and its responses to medical questions have been successful. We examined ChatGPT-4's evaluation of structured 68Ga prostate-specific membrane antigen (PSMA) PET/CT reports of newly diagnosed prostate cancer patients. 68Ga PSMA PET/CT reports of 164 patients were entered to ChatGPT-4. ChatGPT-4 was asked to respond the following questions according to the PET/CT reports: 1-Has the cancer in the prostate extended to organs adjacent to the prostate? 2-Has the cancer in the prostate spread to neighboring lymph nodes? 3-Has the cancer in the prostate spread to lymph nodes in distant areas? 4-Has the cancer in the prostate spread to the bones? 5-Has the cancer in the prostate spread to other organs? ChatGPT-4's responses were scored on a Likert-type scale for clarity and accuracy. The mean scores for clarity were 4.93 ± 0.32, 4.95 ± 0.25, 4.96 ± 0.19, 4.99 ± 0.11, and 4.96 ± 0.30, respectively. The mean scores for accuracy were 4.87 ∓ 0.61, 4.87 ∓ 0.62, 4.79 ± 0.83, 4.96 ± 0.25, and 4.93 ± 0.45, respectively. Patients with distant lymphatic metastases had a lower mean accuracy score than those without (4.28 ± 1.45 vs. 4.94 ± 0.39; p < 0.001). ChatGPT-4's responses in 13 patients (8%) had the potential for harmful information. ChatGPT-4 successfully interprets structured 68Ga PSMA PET/CT reports of reports of newly diagnosed prostate cancer patients. However, it is unlikely that ChatGPT-4 evaluations will replace physicians' evaluations today, especially since it can produce fabricated information.

Diagnostic performance of simultaneous PET-magnetic resonance versus PET-computed tomography in oncology with an overview on clinical utility and referral pattern of PET-magnetic resonance: a single institutional study.

PET-magnetic resonance (PETMR) imaging is an upcoming investigative modality with a few installations in Asia and only three in India. PET-Computed tomography (PETCT) is an established diagnostic cornerstone for oncological indications but with limited resolution for small lesions due to low soft-tissue contrast and additional radiation exposure. Our primary objective was to evaluate the diagnostic performance of simultaneous PETMR and PETCT in lesion detection in oncological practice. Secondly to assess the referral pattern and study the clinical utility of PETMR in a university hospital practice. A total of 100 consecutive biopsy-proven cancer patients (breast or lung malignancy with suspected metastases) underwent 18F fluorodeoxyglucose (FDG) PETMR and PETCT for staging as a single injection, double examination protocol. Morphological lesion detection on correlative imaging/histopathology was used as the gold standard. Analysing the referral pattern, a total of 9366 patients underwent simultaneous PETMR imaging for indications in the past 5 years since installation. 18F FDG PETMR detected 100% of primary tumours in breast/lung carcinoma (Ca) patients while PETCT was positive in 96%. Overall accuracy of nodal metastases detection for PETMR and PETCT was 96 and 88%, while for distant metastases the accuracy was 100 and 93%, respectively. FDG PETMR proved more sensitive and specific than PETCT for regional nodal (P = 0.011 and P < 0.001) and distant metastases detection (P = 0.017 and P < 0.001, respectively). Analysing the general referral pattern for PETMR, the majority were oncology referrals (66.5, 33.5%) when compared to nononcological indications. About 66.24% were FDG based, followed by Ga prostate-specific membrane antigen and dodecane tetraacetic acid. The general utility of PETMR was found incremental in better delineation of small lesions especially in head, neck, liver, brain and gynaecological malignancies. In our past 5 years of PETMR practice, we found that simultaneous PETMR is a highly recommended ideal imaging technique for oncological and nononcological indications. It has excellent diagnostic performance with high sensitivity, specificity and accuracy when compared to PETCT in tumour, nodal metastases staging in specific subgroup of breast and lung malignancy patients.

The added value of 68Ga-PSMA PET/CT in anatomical staging of prostatic carcinoma in correlation with the histopathological zonal staging

BackgroundProstate cancer is well known as the commonest cancer in men and the second leading cause of cancer-related death. CT, MRI and bone scintigraphy are considered the commonly widely used imaging diagnostic tools for detection, staging and follow-up of prostate cancer. Prostate-specific membrane antigen (PSMA) is a membrane glycoprotein, that can be concentrated in prostate cancer cells up to 100 times higher than in normal cells. PSMA-targeted imaging modalities have now proven their efficacy in diagnosis, staging and follow-up of prostate cancer. The use of 68Ga PSMA PET-CT has efficiently improved the detection of loco-regional and metastatic disease. 68Ga PSMA PET-CT also has an effective role in the primary diagnosis, staging, and detecting biochemical recurrence after curative treatment and in metastasis-targeted therapy. This work aims to review the role of 68Ga PSMA PET-CT in anatomical staging of prostate cancer in correlation with histopathological staging.ResultsZonal correlation between 68Ga PSMA findings and biopsy results showed sensitivity ranging between 76.9 and 90.6% and specificity ranging from 85.7 to 100%. There was high significant correlation between the SUVmax uptake and the biopsy results, between the SUVmax uptake and the local staging as well as between the Gleason score and 68Ga PSMA PET/CT findings.Conclusions68Ga PSMA PET/CT is a highly promising imaging modality with an effective role in detection of prostate cancer showing high sensitivity and specificity in prediction of zonal histopathological results and loco-regional Gleason score staging with significant positive correlation between the SUV uptake results, Gleason score and the PSA levels.

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.

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.

68Ga Prostate-specific Membrane Antigen Uptake in Metastatic Medullary Thyroid Carcinoma.

We present the case of a 58-year-old man with advanced medullary thyroid carcinoma who had a treatment history with different types of modalities. In the follow-up, the patient had rising calcitonin and CEA levels. Metastatic lymph nodes, liver, and bone metastases with varying degrees of uptake were detected on 18F-fluorodeoxyglucose (FDG) and 68Ga-DOTATATE positron emission tomography/computed tomography (PET/CT). 68Ga prostate-specific membrane antigen (PSMA) PET/CT was performed to explore whether the patient might have a chance for PSMA-targeted radionuclide therapy, and increased PSMA expression was noted in most of the metastatic lesions, even some of which have higher PSMA uptake than 18F-FDG and 68Ga-DOTATATE.

Oncological Outcomes in Men With Favorable Intermediate Risk Prostate Cancer Enrolled in Active Surveillance.

To evaluate the long-term oncological outcomes in men with intermediate risk prostate cancer (PCa) enrolled in active surveillance (AS). From April 2015 to December 2022, 30 men with Gleason score 3+4/ISUP Grade Group2 (GG2), greatest percentage of cancer (GPC) ≤50%, Gleason pattern 4 ≤10%, ≤3 positive biopsy cores were enrolled in AS. All patients underwent confirmatory transperineal saturation biopsy (SPBx: 20 cores) 12 months from diagnosis plus multiparametric magnetic resonance (mpMRI) evaluation. At the last follow-up, 68Ga prostate-specific membrane antigen (PSMA) positron-emission tomography (PET)/computed tomography (CT) was added: lesions with PIRADS score ≥3 and/or standardized uptake value (SUVmax) >5 were submitted to four targeted cores. Three out of 30 (10%) men with GG2 PCa were reclassified at confirmatory biopsy. At the last follow-up (median 5.2 years), only 2 of 27 (7.4%) men were reclassified and 23/30 (76.6%) continued AS. Men with favorable GG2 PCa enrolled in AS have good long-term oncological results. The use of selective criteria (i.e., SPBx, mpMRI, PSMA PET/CT) reduces the risk of reclassification.

68 Ga-PSMA Uptake in Solar Elastosis.

68 Ga-prostate specific membrane antigen (PSMA) PET/CT scan for staging revealed increased 68 Ga-PSMA uptake in solar elastosis in a patient with prostate cancer. Solar elastosis is a degenerative condition of elastic tissue in the dermis caused by prolonged sun exposure. A few studies have demonstrated 68 Ga-PSMA uptake in cutaneous lesions. This case illustrates another instance of a benign cutaneous lesion accompanied by increased 68 Ga-PSMA uptake.

Total-body PET/CT with half-dose [68Ga]Ga-PSMA-11 for biochemical recurrent prostate cancer: comparable diagnostic value to short axial field-of-view PET/CT with full-dose [68Ga]Ga-PSMA-11.

The objective of this study was to evaluate the diagnostic performance and image quality of total-body positron emission tomography/computed tomography (PET/CT) imaging using a half-dose of [68Ga]Ga-prostate specific membrane antigen ([68Ga]Ga-PSMA) radiotracer, compared to conventional short axial field-of-view PET/CT imaging using a full dose of [68Ga]Ga-PSMA. This retrospective study enrolled 52 patients with biochemical recurrent (BCR) prostate cancer after radical prostatectomy who underwent total-body PET/CT with a half-dose (0.9-1.1MBq/kg) of [68Ga]Ga-PSMA. These patients were matched by baseline characteristics to another 52 BCR patients after prostatectomy who underwent conventional PET/CT with a full dose (1.8-2.2MBq/kg) of [68Ga]Ga-PSMA. The half-dose group was further divided into 5-min (G5) and 2-min (G2) acquisition subgroups. Image quality was assessed through subjective analysis using a 5-point scale and objective measurements of standard uptake value maximum (SUVmax), standard uptake value mean (SUVmean), background variation (BV) of the liver, blood pool, and parotid glands. Additionally, SUVmax and tumor-to-background ratio (TBR) were calculated for lesions. No significant difference in subjective image quality was found between the G2 and full-dose groups (p > 0.05). PET/CT image quality was significantly higher for the G5 versus G2 (p < 0.001) and full-dose groups (p < 0.001). TBR did not differ between the G2 and full-dose groups (4.23 ± 5.21 vs 4.22 ± 3.97, p = 0.99). Liver BV was significantly lower for G2 versus full-dose groups (0.16 ± 0.03 vs 0.20 ± 0.05, p < 0.001). Total-body PET/CT with a half-dose [68Ga]Ga-PSMA yields image quality superior or comparable to that of conventional PET/CT. The utilization of total-body [68Ga]Ga-PSMA PET/CT meets the diagnostic demands of BCR patients, particularly those who exhibit reduced tolerance to prolonged horizontal positioning and scan durations, while simultaneously reducing radiation exposure for the subjects.

Isolated Castrate-resistant Prostate Cancer Metastasis to Both Adrenal Glands Detected on 68Ga PSMA PET/CT.

A 61-year-old male patient, who had undergone radical prostatectomy, underwent 68Ga labeled prostate-specific membrane antigen (PSMA) positron emission tomography/computerized tomography (PET/CT) for evaluation of suspected biochemical recurrence of prostate cancer (PCa). PET/CT scan showed increased 68Ga PSMA expressions in hypodense mass lesions in both adrenal gland localizations. An adrenal gland tru-cut biopsy was performed for the right side, which showed poor-differentiated carcinoma metastases associated with the patient's high-grade PCa. As far as we could determine based on an extensive literature search, this is the second case in which isolated adrenal metastasis was detected by 68Ga PSMA PET/CT study in a patient with PCa.

Differential privacy preserved federated transfer learning for multi-institutional 68Ga-PET image artefact detection and disentanglement

PurposeImage artefacts continue to pose challenges in clinical molecular imaging, resulting in misdiagnoses, additional radiation doses to patients and financial costs. Mismatch and halo artefacts occur frequently in gallium-68 (68Ga)-labelled compounds whole-body PET/CT imaging. Correcting for these artefacts is not straightforward and requires algorithmic developments, given that conventional techniques have failed to address them adequately. In the current study, we employed differential privacy-preserving federated transfer learning (FTL) to manage clinical data sharing and tackle privacy issues for building centre-specific models that detect and correct artefacts present in PET images.MethodsAltogether, 1413 patients with 68Ga prostate-specific membrane antigen (PSMA)/DOTA-TATE (TOC) PET/CT scans from 3 countries, including 8 different centres, were enrolled in this study. CT-based attenuation and scatter correction (CT-ASC) was used in all centres for quantitative PET reconstruction. Prior to model training, an experienced nuclear medicine physician reviewed all images to ensure the use of high-quality, artefact-free PET images (421 patients’ images). A deep neural network (modified U2Net) was trained on 80% of the artefact-free PET images to utilize centre-based (CeBa), centralized (CeZe) and the proposed differential privacy FTL frameworks. Quantitative analysis was performed in 20% of the clean data (with no artefacts) in each centre. A panel of two nuclear medicine physicians conducted qualitative assessment of image quality, diagnostic confidence and image artefacts in 128 patients with artefacts (256 images for CT-ASC and FTL-ASC).ResultsThe three approaches investigated in this study for 68Ga-PET imaging (CeBa, CeZe and FTL) resulted in a mean absolute error (MAE) of 0.42 ± 0.21 (CI 95%: 0.38 to 0.47), 0.32 ± 0.23 (CI 95%: 0.27 to 0.37) and 0.28 ± 0.15 (CI 95%: 0.25 to 0.31), respectively. Statistical analysis using the Wilcoxon test revealed significant differences between the three approaches, with FTL outperforming CeBa and CeZe (p-value < 0.05) in the clean test set. The qualitative assessment demonstrated that FTL-ASC significantly improved image quality and diagnostic confidence and decreased image artefacts, compared to CT-ASC in 68Ga-PET imaging. In addition, mismatch and halo artefacts were successfully detected and disentangled in the chest, abdomen and pelvic regions in 68Ga-PET imaging.ConclusionThe proposed approach benefits from using large datasets from multiple centres while preserving patient privacy. Qualitative assessment by nuclear medicine physicians showed that the proposed model correctly addressed two main challenging artefacts in 68Ga-PET imaging. This technique could be integrated in the clinic for 68Ga-PET imaging artefact detection and disentanglement using multicentric heterogeneous datasets.

Head-to-head comparisons of 68Ga-PSMA-11 and 18F-FDG PET/CT in evaluating patients with upper tract urothelial carcinoma: a prospective pilot study.

To prospectively compare the uptake of 68Ga-prostate specific membrane antigen (68Ga-PSMA)-11 and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in upper tract urothelial carcinoma (UTUC) and investigate the correlation between radiological parameters and pathological features of UTUC. Clinicopathologic and imaging data were collected from 10 UTUC patients who underwent preoperative 68Ga-PSMA-11 and 18F-FDG PET/CT scans. The diagnostic capabilities of both imaging techniques were analyzed and compared in UTUC. Angiogenesis in the malignancies was assessed using Chalkley counting and the expression of folate hydrolase 1 (FOLH1) and glucose transporter1 (GLUT1) in UTUC were evaluated in the surgical specimens. Double immunofluorescence staining of PSMA and CD34 was used to examine tumor neovascularization. Tracer uptake and expression were compared and explored. Additionally, 10 patients with clear cell renal cell carcinoma (ccRCC) were included for prospective, comparative research. Ten UTUC patients with 12 malignant lesions and another 10 ccRCC patients were included. 18F-FDG PET/CT demonstrated a more effective detection of UTUC foci compared to 68Ga-PSMA-11 PET/CT (the SUVmax of 18.48 ± 6.73 vs. 4.38 ± 1.45, P < 0.01). Immunohistochemical analysis revealed a statistically significant difference in the expression of PSMA and GLUT1 in UTUC (P = 0.048), with higher pathological grades showing more intense GLUT1 staining than PSMA (75% vs. 12.5%). The Chalkley counting of angiogenesis in ccRCC was significantly higher than that in UTUC (229.34 vs. 71.67), which was proportional to 68Ga-PSMA-11 PET/CT SUVmax (both P < 0.05). 18F-FDG PET/CT holds better clinical potential for evaluating UTUC and detecting lymph node metastasis compared to 68Ga-PSMA-11 PET/CT, likely due to the relatively scant expression of FOLH1 in tumor neovascular endothelium while the abundant expression of GLUT1 in malignancy. Furthermore, the lower neovascular density in UTUC should not be overlooked.

177Lu-PSMA radioligand therapy for patients with recurrent/metastatic (R/M) salivary gland cancer (SGC): A phase II pilot study.

6099 Background: New treatments are warranted due to limited systemic treatment options for SGC patients (pts). Gallium [68Ga]Ga prostate-specific membrane antigen (PSMA) PET imaging results in SGC pts have demonstrated PSMA expression of SGC and thus indicated that PSMA radionuclide therapy may be a useful option, especially in the case of adenoid cystic carcinoma (AdCC) and salivary duct carcinoma (SDC) subtypes. Therefore, this study (EudraCT number 2019-003857-27) evaluated the safety and efficacy of PSMA-targeted radionuclide therapy in AdCC and SDC pts. Methods: This was a single-center, single-arm, phase II pilot study. R/M AdCC (n = 10) and SDC (n = 5) pts with sufficient PSMA tracer uptake on [68Ga]Ga-PSMA PET imaging, i.e., ≥1 lesion ≥1.5cm with PSMA expression above mean liver level, were treated with 2-4 cycles of 7.4 GBq [177Lu]Lu-PSMA-I&amp;T, with an interval of 6±1 weeks. Baseline imaging was repeated for evaluation 4 weeks after cycle 2; in case of progressive disease (PD) per RECIST 1.1 the treatment was discontinued; otherwise, pts received the full treatment (4 cycles). All pts received whole body post-therapeutic imaging after 1, 24, 48, 72 h and 7d after each cycle. The primary endpoint was safety. Secondary endpoints include the objective response rate, progression-free survival (PFS), and overall survival (OS). Results: Between 6-2020 and 2-2023, 15 AdCC pts and 10 SDC pts were screened for eligibility. Five AdCC pts and 8 SDC pts were screen failures due to insufficient PSMA expression in 11 pts (AdCC n = 4; SDC n = 7) or due to brain metastases in 2 pts (AdCC n = 1; SDC n = 1). Ten AdCC and 2 SDC pts received at least one cycle of 7.4 GBq [177Lu]Lu-PSMA-I&amp;T. The most observed adverse events (grade 1-2) included: nausea (75%), dry mouth (75%), fatigue (67%), and anemia (58%). Two pts (17%) developed grade 3 toxicity; lymphocytopenia (n = 1) and hyponatremia (n = 1). No grade 4-5 toxicities were observed. Two pts (AdCC n = 1; SDC n = 1) received only 1 treatment cycle due to early PD. The interim-treatment evaluation resulted in the discontinuation of treatment after 2 cycles in an additional 3 AdCC and the second SDC pts due to PD. Six AdCC pts received the full treatment (4 cycles); no responses were observed; 3 pts (75%) showed stable disease of more than 3 months after treatment completion (5, 15 and 21 months); 3 pts showed PD at 3 months after treatment completion. Median PFS in 10 AdCC pts was 6.7 months (95%CI: 0.0-15.1); OS was not reached after a median follow-up of 11.9 months. Conclusions: [177Lu]Lu-PSMA-I&amp;T treatment in SGC pts is well-tolerated. The efficacy in AdCC was limited; only stable disease was achieved in 3 out of 10 pts. In most screened SDC pts, PSMA expression was insufficient to undergo [177Lu]Lu-PSMA-I&amp;T treatment; the 2 SDC pts included showed early PD. Dosimetry analyses will be performed to calculate the delivered radiation doses to organs at risk as well as tumor lesions. Clinical trial information: EUCTR2019-003857-27.

68Ga-PSMA PET/CT evaluation in men enrolled in prostate cancer Active Surveillance

To evaluate the accuracy of 68Ga-prostate specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) in the diagnosis of clinically significant prostate cancer (csPCa: Grade Group ≥ 2) in men enrolled in Active Surveillance (AS) protocol. From May 2013 to December 2021 200 men aged between 52 and 74 years (median age 63) with very low risk PCa were enrolled in an AS protocol study. During the follow up 48/200 (24%) men were upgraded and 10/200 (5%) decided to leave the AS protocol. After five years from confirmatory biopsy (range: 48-60 months) 40/142 (28.2%) consecutive patients were submitted to mpMRI and 68Ga-PSMA PET/CT imaging examinations before scheduled repeated biopsy. All the mpMRI (PI-RADS ≥ 3) and 68Ga-PET/TC standardized uptake value (SUVmax) ≥ 5 index lesions underwent targeted cores (mpMRI-TPBx and PSMA-TPBx) combined with transperineal saturation prostate biopsy (SPBx: median 20 cores). Multiparametric MRI and 68Ga-PSMA PET/CT showed 18/40 (45%) and 9/40 (22.5%) lesions suspicious for PCa. In 3/40 (7.5%) men a csPCa (GG2) was found; 68Ga-PSMA-TPBx vs. mpMRI-TPBx vs. SPBx diagnosed 2/3 (66.6%) vs. 2/3 (66.6%) vs. 3/3 (100%) csPCa, respectively. In detail, mpMRI and 68Ga-PSMA PET/TC demonstrated 16/40 (40%) vs. 7/40 (17.5%) false positive and 1 (33.3%) vs. 1 (33.3%) false negative results. Although 68PSMA PET/CT did not improve the detection for csPCa of SPBx (1 false negative result equal to 33.3% of the cases), at the same time, would have spared 31/40 (77.5%) scheduled biopsies showing a better diagnostic accuracy in comparison with mpMRI (83.3% vs. 70.2%).

Impact of 68Ga-PSMA PET/CT in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with enzalutamide.

48 Background: 68Ga prostate specific membrane antigen positron emission tomography/computed tomography (68Ga-PSMA PET/CT) is a highly sensitive diagnostic tool to detect prostate metastatic sites even at low levels of Prostate Specific Antigen (PSA). We evaluated the impact of 68Ga-PSMA PET/CT in patients treated with enzalutamide as first-line therapy for mCRPC. Methods: In an observational prospective study, 67 consecutive mCRPC patients were treated with enzalutamide 160 mg once daily in first-line for mCRPC. 68Ga-PSMA PET/CT was performed at baseline, after 3 months, during follow-up and at PSA/clinical progression. Patients were evaluated on a monthly basis for serological PSA response and safety. We measured at baseline the sum of metabolic total volume (SMTV), mean standardized uptake volume (SSUVmean), maximum standardized uptake volume (SSUVmax) and total lesion activity (STLA), which is the product of SMTV and SSUVmean, for a maximum of 20 lesions. These parameters together with baseline PSA level, Eastern Cooperative Oncology Group performance status (ECOG PS), Gleason Score (GS) and age were analyzed by univariate and multivariate Cox regression models as potential predictors of progression-free survival (PFS) and overall survival (OS). Results: At the moment of the present analysis, 58 mCRPC patients were considered fully evaluable. The median age was 75 years (range, 47-91), ECOG PS was 0 in 47 cases (81%), 1-2 in 11 (19%), GS was &lt;8 in 22 (38%), 8-10 in 36 (62%), the median baseline PSA was 2.66 µg/L (range 0.09-197). We observed a median SMTV of 5.73 cm3, median SSUVmax of 44.85, median SSUVmean of 25.80 and median STLA of 59.66. At the median follow-up of 52 months, median PFS was 28.9 months (95% CI 16.3-43.6), median OS was not reached (95% CI 36.8-not reached). In univariate analysis, SSUVmax and STLA were significant for PFS (p=0.015 and p=0.001, respectively) and OS (p=0.026 and p=0.019, respectively), while SSUVmean was significant only for OS (p=0.028). On multivariate analysis, STLA only remained significant for PFS (p&lt;0.001) and OS (p=0.026). Conclusions: The assessment of mCRPC by 68Ga-PSMA PET/CT before starting enzalutamide was associated with longer median PFS and OS compared to prior studies using standard imaging only. STLA, expression of both volume and intensity of 68Ga-PSMA uptake, appeared the strongest parameter able to predict PFS and OS.

Characteristics of Radiopharmaceutical Uptake in Primary Tumor and Metastatic Lesions of Prostate Carcinoma: Comparison of Oligometastatic with Multimetastatic Disease.

Oligometastases may generate secondary to indolent tumor biology. In this study, we investigated whether semiquantitative measures of 18F-fluorodeoxyglucose (FDG) and gallium-68 (68Ga) prostate-specific membrane antigen (PSMA) uptake of metastatic lesions and prostatic sites are different between oligometastatic (OM) and multimetastatic (MM) disease of prostate carcinoma (PC). Patients with PC, who underwent positron emission tomography/computed tomography (PET/CT) from October 2012 to February 2020 were retrospectively reviewed. Patients, whose reports were consistent with metastatic diseases were selected. Patients classified as with MM or OM disease. Maximum standardized uptake values (SUVmax) were calculated from metastatic lesions and the prostatic site. The median of the SUVmax results between patients with OM and MM disease were compared. A totally 145 patients with a mean age of 71.46±9.26, were evaluated. In 59 of 145 patients, 18F-FDG PET/CT was performed;86 patients had gone through 68Ga PSMA PET/CT. Thirty-seven of 145 patients were OM, whereas 108 patients were MM. The median of the SUVmax of metastatic lesions in patients with OM and MM disease in the 18F-FDG group were 5.60 and 9.51, respectively. The results of the calculated median SUVmax values in OM and MM disease in the Ga-68 PSMA group were 13.44 and 29.84, respectively. A significant difference was observed in the median SUVmax results of metastatic lesions between OM and MM disease (p<0.05). Median values of SUVmax calculated from the prostatic site in OM and MM disease were 7.83 and 12.29 respectively in 18F-FDG; 26.23 and 26.74 in the 68Ga PSMA group. No significant difference was found in the SUVmax results of the prostatic site between OM and MM disease (p>0.05). SUVmax results of metastatic lesions are significantly higher in patients with MM than in patients with OM disease in patients with PC, which may be secondary to their different biological contents in terms of aggressiveness.

Prostate-Specific Membrane Antigen PET Positivity in a Lung Mass: Diagnosis of Diffuse Large B-Cell Lymphoma.

An 84-year-old man with nonmetastatic castrate-sensitive prostate cancer was referred for a 68Ga-prostate-specific membrane antigen (PSMA) PET/CT scan with a prostate-specific antigen level of 3.6 ng/mL for restaging. He was 22 years post-radical prostatectomy and had salvage radiation being managed with intermittent hormonal therapy. Imaging revealed a right lower lobe mass with increased PSMA uptake (SUVmax 6.2). Biopsy and subsequent immunostaining determined the mass to be diffuse large B-cell lymphoma. We report a case of diffuse large B-cell lymphoma diagnosed in the setting of PSMA positivity, highlighting awareness for oncologists and radiologists to know this possibility.

Protocol of the integrated boost to the dominant intraprostatic nodule in stereotactic body radiation therapy for localized prostate cancer.

Aim: To explore the safety and efficacy of the integrated boost to the dominant intraprostatic nodule (DIN) based on 68Ga prostate-specific membrane antigen PET/MRI in stereotactic body radiation therapy (SBRT) for patients with localized prostate cancer. Methods: SBRT regimen is employed - namely, sequential integrated boost (SIB) to the DIN based on 68Gaprostate-specific membrane antigen PET/MRI. SIB prescription dose of 36.25 Gy in five fractions to fixed prophylactic tumoricidal region is delivered, followed by 7.25 Gy in one fraction added to the DIN every other day. The primary end point of the study will be toxicity assessed by the Common Terminology Criteria for Adverse Events 5.0 grading scale. Secondary end points include biochemical progression-free survival, local progression-free survival, distant metastasis-free survival and overall survival. Discussion: This trial is to prove the safety and efficacy of sequential integrated boost to the DIN in SBRT. Clinical Trial Registration: NCT04599699 (ClinicalTrials.gov).

Unexpected Metastatic Localizations of Prostate Cancer Determined by 68Ga PSMA PET/CT: Series of Four Cases.

Prostate-specific membrane antigen (PSMA) is a transmembrane protein with overexpression in most prostate cancer cells. Gallium-68-(68Ga) PSMA positron emission tomography/computed tomography (PET/CT) imaging is a game-changer in the management of prostate cancer. 68Ga PSMA PET/CT scan is advanced and a promising radioligand has high sensitivity in determining lesions of prostate cancer with a high tumor to background ratio. The most common areas of metastasis are the bone and pelvic lymph nodes. The prognosis of prostate cancer is mainly determined by the status of metastases. The presence and the localization of metastases affects treatment planning. In our cases, we presented some examples of uncommon sites of metastases such as the brain, adrenal glands, penis and orbit. Improvements in imaging techniques, such as 68Ga PSMA PET/CT have led to the possibility to make more determi nation of rare metastase sites in prostate cancer patients.