68Ga-PSMA Ligand Research Articles

68Ga-PSMA ligand PET/CT integrating indocyanine green-guided salvage lymph node dissection for lymph node metastasis after radical prostatectomy.

To efficiently remove all recurrent lymph nodes (rLNs) and minimize complications, we developed a combination approach that consisted of 68Gallium prostate-specific membrane antigen (PSMA) ligand positron emission tomography (PET)/computed tomography (CT) and integrated indocyanine green (ICG)-guided salvage lymph node dissection (sLND) for rLNs after radical prostatectomy (RP). Nineteen patients were enrolled to receive such treatment. 68Ga-PSMA ligand PET/CT was used to identify rLNs, and 5 mg of ICG was injected into the space between the rectum and bladder before surgery. Fluorescent laparoscopy was used to perform sLND. While extensive LN dissection was performed at level I, another 5 mg of ICG was injected via the intravenous route to intensify the fluorescent signal, and laparoscopy was introduced to intensively target stained LNs along levels I and II, specifically around suspicious LNs, with 68Ga-PSMA ligand PET/CT. Next, both lateral peritonea were exposed longitudinally to facilitate the removal of fluorescently stained LNs at levels III and IV. In total, pathological analysis confirmed that 42 nodes were rLNs. Among 145 positive LNs stained with ICG, 24 suspicious LNs identified with 68Ga-PSMA ligand PET/CT were included. The sensitivity and specificity of 68Ga-PSMA ligand PET/CT for detecting rLNs were 42.9% and 96.6%, respectively. For ICG, the sensitivity was 92.8% and the specificity was 39.1%. At a median follow-up of 15 (interquartile range [IQR]: 6–31) months, 15 patients experienced complete biochemical remission (BR, prostate-specific antigen [PSA] <0.2 ng ml−1), and 4 patients had a decline in the PSA level, but it remained >0.2 ng ml−1. Therefore, 68Ga-PSMA ligand PET/CT integrating ICG-guided sLND provides efficient sLND with few complications for patients with rLNs after RP.

Soft tissue metastasis of the penis detected by copper-64 labeled prostate-specific membrane antigen positron emission tomography (64Cu-PSMA PET/CT) in a patient with prostate cancer.

Prostate cancer is considered to be the most common solid cancer affecting men worldwide and leading to a significant morbidity and mortality. Metastases are usually seen in bone or lymph nodes. For recurrent disease, PET imaging with 68Ga-PSMA-11 (also known as HBED-CC, Glu-urea-Lys(Ahx)-HBED-CC, and PSMA-HBED-CC) is widely used. However, preparation of 68Ga-PSMA ligand requires the presence of radiochemistry facilities and can therefore not be utilized in centers lacking such facilities. Recently, copper labeled prostate-specific membrane antigen positron emission tomography (64Cu-PSMA PET/CT) demonstrated promising results in patients with recurrent disease and in the primary staging of selected patients with progressive local disease. In the present case, a rare manifestation site of a metastatic lesion in a patient with advanced prostate cancer is detected by 64Cu-PSMA PET/CT.

Prostate-Specific Membrane Antigen: The Target of the Decade, from Biochemical Recurrence to Widespread Adoption.

> FDG—the molecule of the (last) century. PSMA—the target of this and the next decade. > > —Richard P. Baum, fourth Theranostics World Congress (2016), Melbourne, Australia Every year, a myriad of promising new radiopharmaceuticals is described in The Journal of Nuclear Medicine, but few

Detection Rate of 68Ga-PSMA Ligand PET/CT in Patients with Recurrent Prostate Cancer and Androgen Deprivation Therapy.

Prostate-specific membrane antigen (PSMA) ligand PET/CT enables the localization of tumor lesions in patients with recurrent prostate cancer, but it is unclear whether androgen deprivation therapy (ADT) influences diagnostic accuracy. The aim of this study was to evaluate the effect of ADT on the detection rate of 68Ga-PSMA ligand PET/CT. Thus, 399 patients with initial radical prostatectomy and 68Ga-PSMA ligand PET/CT during PSA relapse were retrospectively evaluated. Propensity score matching was used to create two balanced groups of 62 subjects who either did or did not receive ADT within six months before imaging. All 68Ga-PSMA ligand PET/CT were evaluated visually and with semiquantitative measures. The detection rate of tumor recurrence was significantly higher in the group with ADT (88.7% vs. 72.6%, p = 0.02) and improved with increasing PSA-levels in both groups. In subjects with pathological PET/CT and ADT, whole-body total lesion PSMA (p < 0.01) and PSMA-derived tumor volume (p < 0.01) were significantly higher than in those without ADT. More PSMA-positive lesions and higher PSMA-derived volumetric parameters in patients with ADT suggest that a better detection rate is related to a (biologically) more advanced disease stage. Due to high detection rates in patients with PSA-levels < 2 ng/mL, the withdrawal of ADT before PSMA ligand PET/CT cannot be recommended.

Differential impact of radiation therapy after radical prostatectomy on recurrence patterns: an assessment using [68Ga]Ga-PSMA ligand PET/CT(MRI).

To evaluate the differential impact of postoperative radiotherapy (RT) on recurrence patterns in patients treated with radical prostatectomy (RP) using [68Ga]Ga-PSMAHBED-CC conjugate 11 positron emission tomography (PSMA 11-PET). We assessed 162 consecutive patients who experienced biochemical recurrence (BCR) after RP for nonmetastatic prostate cancer (PC). All had at least one positive lesion on imaging. No patient was on androgen deprivation therapy (ADT). Patients were categorized into those who had received adjuvant/salvage RT ± ADT and those who did not (RP only). Lesion- and patient-based analyses were performed. The impact of the radiation field was assessed. Overall, 57 BCR patients underwent RP only, 105 received postoperative RT. Median PSA was 1.01 ng/ml (IQR 0.58-2). In the lesion-based analysis, compared to the RP only patients, those who had received postoperative RT, had less lymph node (LN) recurrences distal to the common iliac bifurcation (35.2 vs. 57.9%, p = 0.05), but were more likely to harbor positive LNs proximal to the iliac bifurcation and in the presacral (34.2 vs. 12.3%, p = 0.002) areas as well as bone metastases (25.7 vs. 8.8%, p = 0.01). In the patient-based analysis, the patients with postoperative RT after RP had less recurrence in the pelvis only (pelvic LNs and/or prostate bed) (52.4 vs. 79%, p = 0.002), but were more likely to harbor extrapelvic recurrence (41.9 vs. 15.8%, p = 0.001). Patients who received RT to the prostate bed only had more recurrence to the pelvic LN only (54.2% vs. 23.4%, p = 0.002), but less extrapelvic recurrence (31.3 vs. 53.2%, p = 0.03) and less bone recurrence (16.7 vs. 36.2%, p = 0.031) compared to those patients, who received RT to the prostate bed and pelvic nodes. Postoperative radiation treatment alters the recurrence pattern in BCR patients after RP. Further prospective studies are needed to establish a decision tree for optimal imaging/management according to previous treatments.

Response assessment using [68 Ga]Ga-PSMA ligand PET in patients undergoing systemic therapy for metastatic castration-resistant prostate cancer.

To assess which parameters of [68 Ga]Ga-PSMA-11 positron emission tomography (PSMA-PET) predict response to systemic therapies in metastatic (m) castration-resistant prostate cancer (CRPC). In addition, to investigate which of these factors are associated with overall survival (OS). We retrospectively assessed the following PSMA-PET parameters in 43 patients before and after systemic therapies for mCRPC: PSMA total tumor volume (TTV), mean standardized uptake value (SUVmean), SUVmax, and SUVpeak. prostate-specific antigen (PSA) levels and PSMA-PET/CT(magnetic resonance imaging [MRI]) imaging were both performed within 8 weeks before and 6 weeks after systemic therapy. PSMA-PET and CT (MRI) images were reviewed according to the modified PET Response Criteria in Solid Tumors (PERCIST) and Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Results were compared to PSA response. Univariable survival analyses were performed. Overall, 43 patients undergoing 67 systemic therapies were included (9 patients radium-223, 12 cabazitaxel, 22 docetaxel, 6 abiraterone, and 18 enzalutamide). Median serum PSA level before any therapy was 11.3 ng/mL (interquartile range [IQR] = 3.3, 30.1). Delta (d) PSA after systemic therapies was -41%, dTTV 10.5%, dSUVmean -7.5%, dSUVmax -13.3%, dSUVpeak -12%, and dRECIST -13.3%. Overall, 31 patients had dPSA response (46.3%), 12 stable disease (17.9%), and 24 progressive disease (35.8%). All observed PET parameters, as well as the RECIST evaluation, were significantly associated with PSA response (dTTV P = .003, dSUVmean P = .003, dSUVmax P = .011, dSUVpeak P < 0001, dRECIST P = .012), while RECIST assessment was applicable in 37 out of 67 patients (55.2%). Within a median follow-up of 33 months (IQR = 26, 38), 10 patients (23.3%) died of PC. On univariable survival analyses, neither the investigated PET parameters nor PSA level or RECIST criteria were associated with OS. PSMA-PET provides reliable parameters for prediction of response to systemic therapies for mCRPC. These parameters, if confirmed, could enhance RECIST criteria, specifically concerning its limitations for sclerotic bone lesions.

Current Status of Radionuclide Renal Cortical Imaging in Pyelonephritis.

Pyelonephritis is an infection of the kidneys that is seen more commonly in children than the adults. 99mTc-dimercaptosuccinic acid (99mTc-DMSA) scanning is a radionuclide imaging study to detect renal scarring after acute pyelonephritis (a late 99mTc-DMSA scan) and also helps to diagnose acute pyelonephritis in febrile urinary tract infections (an acute 99mTc-DMSA scan). Planar imaging in multiple views (posterior and bilateral posterior oblique) is generally used. Pinhole imaging with a high-resolution-collimator magnification of each kidney allows detection of smaller cortical defects. SPECT is optional. SPECT/CT is not recommended in children because it has a higher radiation exposure than routine 99mTc-DMSA scans. The main limitations of 99mTc-DMSA scanning include a relatively long waiting time after radiotracer injection, a long acquisition time, and a high radiation dose, which is particularly important in repeated studies on children and with the limited spatial resolution of γ-cameras. 99mTc-glucoheptonate is an alternative radiotracer when 99mTc-DMSA is not available. Radiotracers for dynamic renal functional imaging can grossly assess the renal cortex in the first few minutes of imaging. 68Ga-prostate-specific membrane antigen ligand (68Ga-PSMA ligand) PET has the ability to provide images of normal renal cortex and demonstrate renal cortical defects from cysts. In this article, we assess the current status of renal cortical imaging and present 68Ga-PSMA ligand PET images. 68Ga-PSMA ligand provides excellent renal cortical images, and studies should be done to compare 68Ga-PSMA ligand PET with 99mTc-DMSA scanning in renal diseases, particularly in pyelonephritis.

526 - Response assessment using 68Ga-PSMA ligand PET in patients undergoing 177Lu-PSMA radioligand therapy for metastatic castration resistant prostate cancer

526 - Response assessment using 68Ga-PSMA ligand PET in patients undergoing 177Lu-PSMA radioligand therapy for metastatic castration resistant prostate cancer

Detection Rate of 18F-Choline PET/CT and 68Ga-PSMA-HBED-CC PET/CT for Prostate Cancer Lymph Node Metastases with Direct Link from PET to Histopathology: Dependence on the Size of Tumor Deposits in Lymph Nodes.

Accurate detection of prostate cancer lymph node metastases (LNM) through PET/CT before lymphadenectomy is crucial for successful therapy. PET/CT with choline derivatives used to be the standard tool for imaging metastases, whereas 68Ga-PSMA (prostate-specific membrane antigen) PET/CT was introduced recently. Both PET techniques were investigated with respect to what extent the detection rate of LNM depends on the size of tumor deposits (TDs) within LNM. Methods: Documenting the switch from the use of 18F-choline to 68Ga-PSMA in 2014, we used 2 patient cohorts undergoing a template lymphadenectomy because of a PET/CT indicating LNM. Forty-four and 40 patients underwent PET/CT with 18F-choline or 68Ga-PSMA ligand, respectively. In total, 226 LNM (125 18F-choline, 101 68Ga-PSMA) originated from 73 salvage lymphadenectomies at biochemical recurrence and from 11 primary lymphadenectomies at radical prostatectomy. LNM eligible for direct correlation of PET/CT to histopathology were identified from lymphadenectomies conducted in small anatomic subregions, with 1 LNM (condition 1) or 1-2 LNM (condition 2). Longitudinal and short diameters of TD within LNM were determined by histopathology, allowing linking of the size of TD in LNM to the detection threshold of PET/CT. Diameters associated with a detection rate of 50% and 90% (d50%, d90%) were calculated on the basis of logistic growth curve models fitted. Results: Gleason score, number of removed LNs, and subregions for lymphadenectomy per patient did not differ significantly between the 18F-choline and 68Ga-PSMA groups. The median prostate-specific antigen level at imaging and number of LNM per patient were significantly higher in the 18F-choline group (3.4 ng/mL, n = 34) than in the 68Ga-PSMA group (2.2 ng/mL, n = 28; both P < 0.05). Longitudinal and short diameters of TD in LNM to reach d90% were 11.2 and 7.4 mm, respectively, for 18F-choline PET/CT and 6.3 and 4.9 mm, respectively, for 68Ga-PSMA PET/CT. Corresponding diameters to reach d50% were 5.5 and 3.3 mm, respectively, for 18F-choline PET/CT and 3.7 and 2.3 mm, respectively, for 68Ga-PSMA PET/CT. Detection rates were significantly higher under 68Ga-PSMA (P = 0.005 and 0.04 for longitudinal and short diameter). Conclusion: 68Ga-PSMA PET/CT is superior to 18F-choline PET/CT in the detection of LNM. Whether those results will lead to an improved patient outcome after 68Ga-PSMA PET-guided therapy needs to be investigated by further studies.

Super Scan in 68Ga-PSMA Ligand PET/CT in Prostate Cancer-Diagnostic Criteria and Its Significance

Super Scan in 68Ga-PSMA Ligand PET/CT in Prostate Cancer-Diagnostic Criteria and Its Significance

Response assessment using 68Ga-PSMA ligand PET in patients undergoing 177Lu-PSMA radioligand therapy for metastatic castration-resistant prostate cancer

PurposeThe first aim of this study was to evaluate 68Ga-PSMAHBED-CC conjugate 11 positron emission tomography (PSMA PET) parameters for assessment of response to 177Lu-PSMA-617 radioligand therapy (RLT) in patients with metastatic castration-resistant prostate cancer (mCRPC). The second aim was to investigate factors associated with overall survival (OS).MethodsWe retrospectively assessed mean standardized uptake values (SUVmean) and total tumor volumes (TTV) on PSMA PET in 38 of 55 mCRPC patients before and after RLT. PSA testing and PSMA PET/CT(MRI) imaging were performed during the 8 weeks before and the 6 weeks after RLT. PSMA PET and CT(MRI) images were reviewed separately according to the modified PET Response Criteria in Solid Tumors (mPERCIST) and RECIST1.1. The results were compared with PSA responses. Associations between OS and the RECIST evaluation and changes in SUVmean, TTV, and PSA, CRP, LDH, hemoglobin and ALP levels were determined in a univariable survival analysis.ResultsThe median PSA level at the time of pretherapy PSMA PET/CT(MRI) was 60.8 ng/ml (IQR 15.4, 264.2 ng/ml). After RLT the median PSA level decreased by 44%, TTV by 45.1%, SUVmean by 25.8% and RECIST by 11.3%. A PSA response was seen in 18 patients (47.4%), stable disease in 12 (31.6%) and progressive disease in 8 (21.1%). Contrary to the changes in SUVmean and the RECIST evaluation, the change in TTV was significantly associated with PSA response (p = 0.15, p = 0.58, and p < 0.001, respectively). After a median follow-up of 17 months (IQR 8.0, 24.2 months), 11 patients (28.9%) had died of their prostate cancer. The changes in both TTV and PSA levels were associated with OS (HR 1.001, 95% CI 1–1.003, p = 0.04, and HR 1.004, 95% CI 1.001–1.008, p = 0.01, respectively), while the changes in SUVmean and the RECIST evaluation were not. The pre-therapy CRP level was also associated with OS (HR 1.07, 95% CI 1.009–1.14, p = 0.02).ConclusionTTV on PSMA PET seems to be a reliable parameter for response assessment in mCRPC patients undergoing RLT and might overcome the limitations of RECIST in prostate cancer. Furthermore, the change in TTV was significantly associated with OS in our cohort.

1342P - 68Ga-PSMA-PET/CT imaging for locally advanced, recurrent and metastatic adenoid cystic carcinoma and salivary duct carcinoma

Background: Salivary gland cancer (SGC) is a rare cancer with few treatment options. Adenoid cystic carcinoma (ACC) and salivary duct carcinoma (SDC) are major subtypes of SGC which often show immunohistochemical expression of prostate-specific membrane antigen (PSMA). In prostate cancer, PSMA ligands labeled with radioisotopes such as 68Ga or 177Lu, are used for imaging or therapy. The aim of this study was to evaluate 68Ga-PSMA ligand uptake in patients with locally recurrent and/or metastatic ACC and SDC and to establish the diagnostic value of 68Ga-PSMA-PET/CT imaging compared to full-dose CT imaging. Methods:68Ga-PSMA-HBED-CC PET/CT scans were performed in 14 ACC patients and 10 SDC patients including a full-dose CT scan of the neck, chest and abdomen. 68Ga-PSMA ligand uptake was evaluated in local recurrences and metastatic lesions. Detected lesions were compared to CT results. Maximum standardized uptake values (SUVmax) were determined. The study protocol was approved by the local medical ethical committee and a written informed consent was obtained from all patients. Results: Moderate to intense PSMA ligand uptake was observed in local recurrences and distant metastases in all ACC patients and 40% of SDC patients. In addition, PSMA-PET imaging detected additional bone metastases in 2 ACC patients and additional lymph node metastases in 1 ACC patient which were not detected on a full-dose CT scan. In 1 ACC patient a local recurrence of a vulvar ACC was suspected on CT but PSMA-PET imaging was negative, which turned out to be scar tissue, eventually. Conclusions: PSMA-PET imaging showed moderate to intense ligand uptake in local recurrences and distant metastases of all ACC patients and 40% of SDC patients. Based on the high uptake, these patients may be promising candidates for 177Lu-PSMA radioligand therapy in future. Moreover, PSMA-PET imaging has added diagnostic value compared to full-dose CT imaging. Clinical trial identification: NCT03319641. Legal entity responsible for the study: Radboud university medical center, Nijmegen, the Netherlands. Funding: Adenoid Cystic Carcinoma Research Foundation (ACCRF) and the Dutch Salivary Gland Cancer Patient Platform. Disclosure: All authors have declared no conflicts of interest.

54 - 68Ga-PSMA ligand PET/CT in patients with biochemical recurrence after prostate cancer treatment – initial data

54 - 68Ga-PSMA ligand PET/CT in patients with biochemical recurrence after prostate cancer treatment – initial data

Patterns of relapse as determined by 68Ga-PSMA ligand PET/CT after radical prostatectomy : Importance for tailoring and individualizing treatment.

To evaluate the patterns of relapse and impact on the intended treatment when using 68Ga-prostate-specific membrane antigen (PSMA) ligand positron emission tomography/computed tomography (PET/CT) imaging for restaging of disease in patients with biochemical relapse after radical prostatectomy (RP) before salvage radiotherapy (sRT). In all, 39patients with biochemical recurrence after RP who had no primary indication for adjuvant RT due to the absence of biologically unfavorable disease (e.g., extracapsular extension, seminal vesicle invasion, positive margins, or lymph node involvement) underwent a 68Ga-PSMA ligand PET/CT for planning of sRT. PET/CT was positive in 84.6% (33/39) of patients. A total of 61lesions were observed in these patients (on average 1.8lesions per patient); 30.3% (10/33) of patients had locally recurrent disease in the prostatic bed. The clinical TNM stage (TNM: tumour-lymph nodes-metastasis-classification) was altered in 69.7% (23/33) of patients following PET, resulting in individualized treatment concepts. A prostate-specific antigen (PSA) >1.0 ng/mL was significantly associated with an increased risk of extrapelvic metastatic disease (p= 0.048). The PSA level at the time of PSMA ligand PET/CT correlated with the peak standardized uptake value (SUVpeak; p= 0.002). According to current clinical guidelines, the remaining 15.4% (6/39) of patients without evidence of disease on PET received sRT with a dose of 66.0 Gy. Our results suggest that in patients with biochemical recurrence who did not receive early sRT, a 68Ga-PSMA ligand PET/CT for restaging of disease allows for tailoring and individualizing treatment. Particularly in patients with PSA levels above 1.0 ng/mL, a 68Ga-PSMA ligand PET/CT should be performed for therapy planning, since patients often have metastases not confined to the pelvis.

Multiple Time-Point 68Ga-PSMA I&T PET/CT for Characterization of Primary Prostate Cancer: Value of Early Dynamic and Delayed Imaging.

The aims of this study were to gain mechanistic insights into prostate cancer biology using dynamic imaging and to evaluate the usefulness of multiple time-point Ga-prostate-specific membrane antigen (PSMA) I&T PET/CT for the assessment of primary prostate cancer before prostatectomy. Twenty patients with prostate cancer underwent Ga-PSMA I&T PET/CT before prostatectomy. The PET protocol consisted of early dynamic pelvic imaging, followed by static scans at 60 and 180 minutes postinjection (p.i.). SUVs, time-activity curves, quantitative analysis based on a 2-tissue compartment model, Patlak analysis, histopathology, and Gleason grading were compared between prostate cancer and benign prostate gland. Primary tumors were identified on both early dynamic and delayed imaging in 95% of patients. Tracer uptake was significantly higher in prostate cancer compared with benign prostate tissue at any time point (P ≤ 0.0003) and increased over time. Consequently, the tumor-to-nontumor ratio within the prostate gland improved over time (2.8 at 10 minutes vs 17.1 at 180 minutes p.i.). Tracer uptake at both 60 and 180 minutes p.i. was significantly higher in patients with higher Gleason scores (P < 0.01). The influx rate (Ki) was higher in prostate cancer than in reference prostate gland (0.055 [r = 0.998] vs 0.017 [r = 0.996]). Primary prostate cancer is readily identified on early dynamic and static delayed Ga-PSMA ligand PET images. The tumor-to-nontumor ratio in the prostate gland improves over time, supporting a role of delayed imaging for optimal visualization of prostate cancer.

50 - 68Ga-PSMA ligand PET/CT in patients with prostate cancer: First experience

50 - 68Ga-PSMA ligand PET/CT in patients with prostate cancer: First experience

68Ga-PSMA Ligand PET/CT-based Radiotherapy for Lymph Node Relapse of Prostate Cancer After Primary Therapy Delays Initiation of Systemic Therapy

To evaluate 68Ga-PSMA ligand positron-emission tomography-computed tomography (PET/CT)-based radiotherapy for lymph node metastases of prostate cancer after primary therapy. Twenty-three patients received radiotherapy for PSMA ligand-positive lymph node metastases. The median follow-up time was 12.4 (range=6.0-28.5) months. The median pre-treatment prostate-specific antigen (PSA) decreased from 2.75 (range=0.52-8.92) ng/ml to a nadir of 1.37 (range=0.11-8.00) ng/ml (p=0.001) following radiotherapy. Except for one patient (4.4%), PSA level decreased in 22 patients (95.6%). The biochemical failure-free survival and time to initiation of systemic therapy at the median follow-up were 95.6% and 100%, respectively. Three patients (12.9%) presented with recurrent disease outside the initial radiation field. No grade III acute toxicities or late grade II toxicities were observed. 68Ga-PSMA ligand PET/CT-based radiotherapy is a promising local treatment option for isolated lymph node metastases of prostate cancer.

Detection Efficacy of Hybrid 68Ga-PSMA Ligand PET/CT in Prostate Cancer Patients with Biochemical Recurrence After Primary Radiation Therapy Defined by Phoenix Criteria.

The aim of this retrospective study was to evaluate the detection rate of Glu-NH-CO-NH-Lys-(Ahx)-[68Ga(HBED-CC)] (68Ga-PSMA ligand; PSMA is prostate-specific membrane antigen) PET/CT in patients with biochemical recurrent prostate cancer defined by Phoenix criteria after external-beam radiotherapy or brachytherapy as primary treatment. Methods: One hundred eighteen patients with a median prostate-specific antigen (PSA) of 6.4 ng/mL (range, 2.2-158.4 ng/mL; interquartile range, 4.2-10.2 ng/mL) were finally eligible for this retrospective analysis. Seventy-seven and 41 patients had been treated by external-beam radiotherapy or brachytherapy, respectively. Of the 118 patients, 45 were receiving androgen-deprivation therapy (ADT) within at least 6 mo before the PET/CT. The detection rates were stratified by PSA. The influence of primary Gleason score and ADT was assessed. Relationships between SUV and clinical as well as pathologic features in patients with positive findings were analyzed using univariate and multivariable linear regression models. Results: One hundred seven of 118 patients (90.7%) showed pathologic findings indicative for tumor recurrence in 68Ga-PSMA ligand PET/CT. The detection rates were 81.8% (36/44), 95.3% (41/43), and 96.8% (30/31) for PSA of 2 to <5, 5 to <10, and ≥10 ng/mL, respectively (P = 0.0377). 68Ga-PSMA ligand PET/CT indicated local recurrence in 68 of 107 patients (63.5%), distant lesions in 64 of 107 patients (59.8%), and local recurrence as well as distant lesions in 25 of 107 patients (23.4%). The detection rate was significantly higher in patients with ADT (97.7%) versus without ADT (86.3%, P = 0.0381), but independent from primary Gleason score ≥ 8 (92.0%) versus ≤ 7 (90.2%, P = 0.6346). SUVmax and SUVmean were significantly associated with PSA and ADT (P = 0.018 and 0.004 for SUVmax, respectively; P = 0.025 and 0.007 for SUVmean, respectively). Conclusion:68Ga-PSMA ligand PET/CT demonstrates high detection rates in patients with biochemical recurrence of prostate cancer after primary radiation therapy. The detection rate was positively associated to increasing PSA as well as concomitant ADT. 68Ga-PSMA ligand PET/CT enables discrimination of local versus metastatic disease and thus might have a crucial impact on further clinical management. A major limitation of this study is the lack of histopathologic proof in most patients.

64Cu-PSMA-617 PET/CT Imaging of Prostate Adenocarcinoma: First In-Human Studies.

The prostate-specific membrane antigen (PSMA) is a cell surface protein, which is overexpressed in nearly all cases of prostate cancer (PCa). PET imaging with 68Ga-PSMA-HBED-CC has recently found widespread application in the diagnosis of recurrent PCa. In this study, the diagnostic potential of 64Cu-labeled PSMA ligand (PSMA-617) PET in patients with PCa has been investigated. The study was conducted simultaneously at two nuclear medicine centers, Austria (Vienna, Center 1) and Germany (Bad Berka, Center 2). The patients (n = 29) included in this study were referred for PET (Center 1, 21 patients) or PET/CT (Center 2, 8 patients) imaging with either a high suspicion of recurrent disease or for possible surgical or PSMA radioligand therapy planning. PET images of the whole body were performed at 1 hour p.i. and additional images of the pelvis at 2 hours p.i. In 23 of 29 patients, at least one focus of pathological tracer uptake suspicious for primary disease in the prostate lobe or recurrent disease was detected. Among healthy organs, the salivary glands, kidneys, and liver showed the highest radiotracer uptake. Lesions suspicious for PCa were detected with excellent contrast as early as 1 hour p.i. with high detection rates even at low prostate-specific antigen (PSA) levels. The preliminary results of this study demonstrate the high potential of 64Cu-PSMA ligand PET/CT imaging in patients with recurrent disease and in the primary staging of selected patients with progressive local disease. The acquired PET images showed an excellent resolution of the detected lesions with very high lesion-to- background contrast. Furthermore, the long half-life of 64Cu allows distribution of the tracer to clinical PET centers that lack radiochemistry facilities for the preparation of 68Ga-PSMA ligand (satellite concept).

(68)Ga-PSMA ligand PET/CT in patients with prostate cancer: How we review and report.

Recently, positron emission tomography (PET) imaging using PSMA-ligands has gained high attention as a promising new radiotracer in patients with prostate cancer (PC). Several studies promise accurate staging of primary prostate cancer and restaging after biochemical recurrence with 68Ga-PSMA ligand Positron emission tomography/computed tomography (PET/CT). However, prospective trials and clinical guidelines for this new technique are still missing. Therefore, we summarized our experience with 68Ga-PSMA ligand PET/CT examinations in patients with primary PC and biochemical recurrence. It focuses on the technical and logistical aspects of 68Ga-PSMA ligand PET/CT examination as well as on the specific background for image reading discussing also potential pitfalls. Further, it includes relevant issues on free-text as well as structured reporting used in daily clinical routine.