Ga-68 Prostate-specific Membrane Antigen Research Articles

Role of Ga68 Prostate-Specific Membrane Antigen Positron Emission Tomography-Computed Tomography in Prostate Cancer Imaging

Role of Ga68 Prostate-Specific Membrane Antigen Positron Emission Tomography-Computed Tomography in Prostate Cancer Imaging

The role of PSMA PET/CT in predicting downgrading in patients with Gleason score 4+4 prostate cancer in prostate biopsy

BackgroundTo investigate the predictable parameters associated with downgrading in patients with a Gleason score (GS) 8 (4+4) in prostate biopsy after radical prostatectomy.MethodsWe retrospectively analyzed 62 patients with a GS of 4+4 on prostate biopsy who underwent robotic radical prostatectomy between 2017 and 2022.Results38 of 62 (61.2%) were downgraded. In multivariable logistic regression model, Ga-68 prostate-specific membrane antigen (PSMA) positron-emission tomography (PET)/computed tomography (CT) SUV max was independent predictor of downgrading (OR 0.904; p = 0.011) and a Logistic Regression model was constructed using the following formula: Y = 1.465–0.95 (PSMA PET/CT SUV max). The model using this variable correctly predicted the downgrading in 72.6% of patients. The AUC for PSMA PET/CT SUV max was 0.709 the cut off being 8.8.A subgroup analysis was performed in 37 patients who had no other European Association of Urology (EAU) high risk features. 25 out of 37 (67.5%) were downgraded, and 21 of these 25 had organ confined disease. Low PSMA SUV max (<8.1) and percentage of GS 4+4 biopsy cores to cancer bearing cores (45.0%) were independently associated with downgrading to GS 7.ConclusionPSMA PET/CT can be used to predict downgrading in patients with GS 4+4 PCa. Patients with GS 4+4 disease, but no other EAU high risk features, low percentage of GS 4+4 biopsy cores to cancer bearing cores, and a low PSMA PET/CT SUV max are associated with a high likelihood of the cancer reclassification to intermediate risk group.

Association of Pre-Treatment Serum Testosterone Levels with Prostate Cancer: A Prospective Study

Introduction: It has been widely accepted that prostate cancer (PCa) growth is related to serum testosterone (ST). A direct correlation between pre-treatment ST level and PCa growth and progression has been reported. However, recent studies have shown that pre-treatment ST levels have a negative correlation with PCa. Thus, the literature is, at best, conflicting. In this study, we examined the pre-treatment serum total testosterone (ST) levels in PCa. Methods: In this prospective observational study, suspected cases of PCa underwent digital rectal examination, routine blood investigation, Prostate-Specific Antigen (PSA) measurement, and prostate biopsy. Diagnosed cases of PCa without any risk factors affecting testosterone levels were included. Their pre-treatment total ST levels were measured. All patients underwent staging evaluation with either Magnetic Resonance Imaging (MRI) &amp; Bone scan or Ga-68 Prostate Specific Membrane Antigen Positron Emission Tomography (PSMA PET). ST levels were also measured in patients with Benign Prostatic Hyperplasia (BPH) and compared with those in PCa patients. ST levels were also assessed according to Gleason Score (GS) and clinical stage in PCa. Results: 110 cases and 54 patients with BPH were included in the study. The median ST level in PCa patients was significantly lower as compared to BPH patients [352.28 ng/dL (Interquartile Range (IQR) 224.99-563.17) vs. 448.29 ng/dL (IQR 400.97-596.42) (p =0.004)]. The median ST level in metastatic PCa was significantly lower than the localized PCa group [298.20 ng/dL vs. 452.30 ng/dL (p=0.0001)]. Moreover, the median ST level was also significantly lower in patients with Gleason Score ≥ 8 than those with Gleason Score ≤ 7 [285.92 ng/dL (149.97-560.40) vs. 425.13 ng/dL (320.43-571.46) (p=0.002)]. Conclusion: This study shows lower ST levels in patients with PCa compared to patients with BPH, thus supporting a potential association as described in previous studies. ST levels may have prognostic value since a low pre-treatment ST level is associated with a higher clinical stage and aggressive 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.

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.

Hybrid Ga-68 prostate-specific membrane antigen PET/MRI in the detection of skeletal metastasis in patients with newly diagnosed prostate cancer: Contribution of each part to the diagnostic performance.

Bone metastasis is essential in patients with prostate cancer (PCa) as it determines prognosis and survival. Hybrid PET/MRI allows simultaneous acquisition of PET and MRI data, thus combining the strength of both technologies allows the detection of bone marrow metastases that are missed by PET/CT. In this retrospective study, we aimed to evaluate the diagnostic efficiency of hybrid PET/MRI with Ga-68 prostate-specific membrane antigen (PSMA) in detecting skeletal metastases in newly diagnosed PCa patients and compared the effectiveness of stand-alone PSMA PET reviewing versus stand-alone whole-body (WB) MRI evaluation. We also investigated the effect of the interpretation of all PET/MR data together on clinical management. We studied 74 newly diagnosed PCa patients who underwent PSMA PET/MRI for staging purposes. At first, PET and MRI were evaluated separately for bone lesions on a patient-and-lesion basis and then a further joint PSMA PET/MRI interpretation was made. Patient-based sensitivity, specificity, positive predictive value, negative predictive value and accuracy analysis for bone metastasis was, respectively, 1.0, 0.83, 0.54, 1.0, 0.86 for PET; 0.75, 0.96, 0.81, 0.95, 0.93 for WB MRI and 0.91, 0.95, 0.78, 0,98, 0.94 for PET/MRI. The combined PET/MRI evaluation changed the clinical impact in 13.5% of patients (eight correct and two wrong decisions) compared to PET stand-alone interpretation. PSMA PET imaging showed superior sensitivity to WB MRI in detecting bone metastases in newly diagnosed PCa patients, whereas WB MRI has superior specificity and PPV. Furthermore, the specificity and PPV of joint PET/MRI evaluation are better than PSMA PET alone. Despite the longer acquisition period, adding WB MRI sequences to PSMA PET imaging appears beneficial for PCa patient management.

Significance of metabolic tumor volume and total lesion uptake measured using Ga-68 labelled prostate-specific membrane antigen PET/CT in primary staging of prostate cancer.

To evaluate the accuracy of Ga-68 prostate-specific membrane antigen positron-emission-tomography and computed-tomography(PSMA-PET/CT) in primary nodal staging of prostate cancer (PCa), and the predictive value of volumetric parameters derived from Ga-68- PSMA-PET/CT data in lymph node(LN) metastasis and correlation with histopathological and surgical outcomes. Seventy-seven patients with newly diagnosed, biopsy-proven PCa who underwent Ga-68-PSMA-PET/CT for primary staging of disease and underwent radical prostatectomy with extendend pelvic LN dissection were evaluated retrospectively. 2 experienced nuclear medicine specialists have retrospectively reviewed PET/CT images blinded to all histopathological and clinical data. Sensitivity, specificity, positive predictive value(PPV), and negative predictive value(NPV) for the detection of LN metastases were analyzed per-patient. Volumetric and semiquantitative PET parameters of the primary prostate lesions including SUVmax,metabolic tumor volume(MTV), and total lesion uptake(TLU) were measured and recorded. Primary tumor SUVmax, MTV and TLU were found significantly higher in patients who were in higher ISUP Grade groups 3,4,5 after surgical treatment (P = 0.021,P = 0.049,P = 0.032, respectively). The sensitivity, specificity, PPV and NPV on LN metastasis detection of Ga-68-PSMA-PET/CT was found 60%, 91%, 82% and 78% respectively. Although the distribution of the measured primary tumor MTV and TLU values were higher in histopathologically proven LN metastasis positive patients compared to negative patients, only TLU was statistically significant(P = 0.023). Increase in primary tumor TLU values were correlated with higher pT stages and surgical margin positivity(P = 0.034). Ga-68-PSMA-PET/CT is of clinically valuable for primary staging. Measuring and adding these 2 parameters in routine clinical evaluation may increase the prediction power of high-grade disease confirmed by surgery.

A Case Report: Application of 68Ga-PSMA-PET/CT for the Diagnosis of Bone Metastases in Patients with Low Prostate-Specific Antigen Levels

Prostate cancer is the second most common type of cancer in men worldwide. It is one of the 5 most common cancer types and contributes to the greatest number of deaths among male patients. It is most common for prostate cancer to metastasize to the vertebrae, ribs, and pelvis. An important determinant of bone metastasis is the level of prostate-specific membrane antigen (PSMA). The risk of metastatic disease is low in patients who have low serum prostate-specific antigen (PSA) levels. This study examined a patient with suspected bone metastasis based on computed tomography (CT), which is considered to be a rare condition, but whose PSA level was abnormally low. 68Ga-PSMA-PET/CT scans were performed on the patient. It was discovered that bone metastases had developed in several regions of the patients’ body. Several sclerotic lesions were observed in the lumbar vertebrae and bilateral iliac wings, suggesting that bone metastases had occurred. An examination of the pelvis revealed a lesion exhibiting Ga-68 PSMA uptake, with a SUVmax of 4.97. Furthermore, laps with Ga-68 PSMA involvement with SUVmax: 8.65 could also be seen in the paracaval and aortokaval regions.

Normal Variants, Pitfalls, and Artifacts in Ga-68 Prostate Specific Membrane Antigen (PSMA) PET/CT Imaging

The advent of gallium 68 prostate specific membrane antigen (PSMA) PET imaging has revolutionized the diagnosis and treatment of prostate cancer. PSMA is a transmembrane glycoprotein that is overexpressed in prostate cancer and yields images with high tumor-to-background contrast. Effective “one-stop-shop” imaging of the prostate, lymph nodes, soft tissue, and bone is achieved with PSMA PET. Compared to conventional imaging, PSMA PET provides superior sensitivity and specificity and plays a pivotal role in staging high-risk prostate cancer as well as in biochemical recurrence by identifying oligometastatic disease. PSMA PET furthermore assists in the selection of patients with metastatic castrate resistant prostate cancer for possible treatment (e.g., labeled with a beta emitter lutetium 177) by using a theranostic approach. The term “prostate specific” is a misnomer as PSMA is also present in other malignant and benign conditions since it acts as a folate hydrolase. To avoid pitfalls and false-positives, a sound knowledge of the normal biodistribution of PSMA as well as other potential causes for false-positive uptake is imperative. This review will describe the expected patterns of distribution of Ga 68 PSMA PET imaging and the common pitfalls noted in published literature since the topic is still evolving.

Perineum and penile invasion of recurrent prostate carcinoma shown by Ga-68 PSMA PET/CT

Imaging of prostate cancer has recently had new modalities. Ga-68 Prostate Specific Membrane Antigen (PSMA) Positron Emission Tomography/Computed Tomography (PET/CT) has gained important diagnostic role in the management of the patients with prostate cancer. Patients with progressively elevated serum prostate specific antigen (PSA) level may be evaluated by Ga-68 PSMA PET/CT imaging. This case report presents a seventy five year old man with diagnosis of prostate cancer and progressive serum PSA increase. Local recurrence of the tumor as well as spread to the penis, perineum and skeleton was determined by Ga-68 PSMA imaging. This case illustrates that Ga-68 PSMA imaging may show unexpected sites of disease spread.

Obstructive Jaundice: An Unusual Presentation of Neuroendocrine Differentiation in Prostatic Adenocarcinoma.

An elderly male on androgen deprivation therapy for prostatic adenocarcinoma presented with obstructive jaundice. Since biopsy from the head of the pancreas showed neuroendocrine carcinoma (NEC), he was diagnosed with second primary pancreatic NEC. Ga-68 DOTANOC positron emission tomography/computed tomography (PET/CT) done subsequently showed enlarged mildly DOTANOC-avid retroperitoneal nodes infiltrating the pancreas. These nodes were found to be progression of prostate-specific membrane antigen (PSMA) nonavid retroperitoneal nodes visualized in his Ga-68 PSMA PET/CT performed at another institution before 4 months, when there was no lesion in the pancreas. This observation revised the diagnosis from second primary pancreatic NEC to progression of neuroendocrine differentiation in preexisting prostatic adenocarcinoma.

Unusual presentation of castrate-resistant prostate cancer with urethral and inguinal nodal metastasis.

Metastatic involvement of the urethra is a rare finding in patients with carcinoma prostate. The signs and symptoms overlap with those of a primary urethral malignancy. The diagnosis is made following a biopsy of the suspected lesions. We describe the case of a 66-year-old patient with carcinoma prostate who presented with penile pain, 18 months after the treatment with androgen deprivation therapy. Ga-68 prostate-specific membrane antigen positron emission tomography/computed tomography helped in the identification of the urethral and inguinal nodal metastasis, which was confirmed histologically. We also discuss the management of this unusual clinical scenario.

Differentiating benign and malignant pancreatic masses: Ga-68 PSMA PET/CT as a new diagnostic avenue.

Differentiation of malignant and benign pancreatic lesions on anatomical imaging is difficult in some cases with overlapping features. Prostate-specific membrane antigen (PSMA) is overexpressed during angioneogenesis in many tumors. We aimed to evaluate the PSMA expression in pancreatic lesions to differentiate these lesions and explore the performance of Ga-68 PSMA-PET/CT vis-a-vis F-18 FDG-PET/CT. Patients with pancreatic lesions on conventional imaging were prospectively recruited. All the patients underwent a whole-body F-18 FDG-PET/CT and a regional abdominal Ga-68 PSMA-PET/CT. Focal tracer uptake (FDG or PSMA) on PET images was considered positive. Histopathology and/or cytopathology were considered the reference standard. A total of forty patients (27 males, mean age 55.3 ± 9.8, range 37-71years) were enrolled. Of these, 19 were diagnosed as malignant on histopathology/cytology. Patients with benign lesions showed no worsening of symptoms for at least 6months on follow-up. FDG-PET/CT revealed 17 true-positive (TP), 9 false-positive (FP), 12 true-negative (TN), and 2 false-negative (FN) findings, whereas PSMA-PET/CT had 18 TP, 2 FP, 19 TN, and 1 FN finding. The sensitivity, specificity, PPV, NPV, and accuracy for FDG-PET/CT were 89.5%, 57.1%, 65.4%, 85.7%, and 72.5%, respectively, while for PSMA-PET/CT were 94.7%, 90.5%, 90%, 95%, and 92.5%, respectively. ROC curve analysis showed that the SUVmax value of 4.8 on PSMA-PET/CT could predict the malignant potential of a lesion with a specificity of 90.5% and a sensitivity of 84.2%. Ga-68 PSMA-PET/CT imaging helped in establishing a non-invasive pre-operative diagnosis of primary pancreatic malignancy with a higher degree of specificity and accuracy compared with FDG-PET/CT. • Conventional imaging such as CT and MRI are unable to reliably differentiate localized malignant pancreatic lesion from benign lesions mimicking malignancy such as mass-forming pancreatitis. • FDG PET/CT helps in detecting malignant foci in view of their increased glucose metabolism. However, it may be falsely positive in inflammatory lesions which may occasionally hinder its ability to differentiate between benign and malignant lesions. • Apart from prostatic malignancy, PSMA is overexpressed in neovasculature of many non-prostatic malignancies. The present study highlights that Ga68 PSMA PET/CT performed better in diagnosing malignancy non-invasively than FDG-PET/CT with a higher PPV (90.5% vs. 65.4%) and accuracy (92.5% vs. 72.5%).

The Role of Ga-68 PSMA PET/CT Scan on Differentiating of Oligometastatic and High Risk Prostate Cancer

Objectives:In this study, we aimed to investigate whether Ga-68 prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) scanning is adequate to predict intermediate risk, high risk, or oligometastatic prostate cancer (PCa) as an initial staging modality.Methods:The Ga-68 PSMA PET/CT scan images of 50 PCa patients pathologically proven by transrectal ultrasound guided biopsy were evaluated retrospectively. The association of standard uptake value maximum (SUVmax) value of the area with the highest PSMA expression within the primary tumor with the risk groups and metastatic burden is investigated.Results:The SUVmax value was 6.18 in oligometastatic patients where it was measured as 10.93 in patients with higher metastatic burden (p=0.037). The cut-off SUVmax value for multiple metastases was 7.96 (p=0.047). According to the regression model, SUVmax value has a positive influence [odds ratio (OR)=1.42], which was statistically significant (p=0.038). SUVmax values for intermediate and high risk patients were 6.91 and 11.44, respectively (p=0.014). The cut-off SUVmax value for the high risk group was 10.55 (p=0.006). In the regression model, SUVmax value has a positive influence (OR=1.198), which was statistically significant (p=0.021).Conclusion:In this paper, we demonstrated the association between SUVmax value of primary tumor and Gleason score. Our results also allowed us to suggest that primary tumor SUVmax is a sufficiently accurate predictor of D’Amico risk groups in newly diagnosed PCa cases. Additionally, Ga-68 PSMA PET/CT turns out to be a useful tool in determining oligometastatic PCa, which requires a different treatment approach.

What is the Prostate Specific Antigen Cut-off Value to Detect Metastases in Ga-68 Prostate Specific Membrane Antigen Ligand Positron Emission Tomography/ Computer Tomography Imaging for Intermediate and High-risk Prostate Cancer?

What is the Prostate Specific Antigen Cut-off Value to Detect Metastases in Ga-68 Prostate Specific Membrane Antigen Ligand Positron Emission Tomography/ Computer Tomography Imaging for Intermediate and High-risk Prostate Cancer?

Performance of Ga-68 PSMA PET/CT for diagnosis and grading of local prostate cancer.

BackgroundWe aimed to evaluate the utility of prostate-specific membrane antigen (PSMA) PET/CT for the detection of local disease within the prostate.MethodsThis is a retrospective review of a single-center experience evaluating intraprostatic detection rates compared with final histopathology in a radical prostatectomy (RP) population. Seventy-two patients had PSMA PET/CT scan performed as part of their primary staging. Intraprostatic PSMA PET/CT avidity was assessed. PSMA PET/CT uptake was retrospectively correlated with patient characteristics including final histopathology, MRI Prostate Imaging Reporting and Data System (PI-RADS) score, clinical tumor stage, prostate-specific antigen (PSA) level, and patient age.ResultsThe sensitivity of PSMA PET/CT for the detection of RP-confirmed prostate cancer was 81.2%. Much higher sensitivity was found within certain subpopulations. The patient characteristics that most strongly correlated with focal intraprostatic PSMA PET/CT uptake were patient age (Kendall's tau coefficient τb = 0.24, p < 0.05) and clinical T stage (τb = 0.21, p < 0.05).The International Society of Urological Pathology (ISUP) grade group from final RP was predicted by standardized uptake value (SUVmax) and to a lesser extent PSA and the maximal dimension of PET-avid lesions. SUVmax monotonically increased with ISUP grade group. If SUVmax was above 10 g/mL, the final RP histopathology had a relative risk of 2.3 (95% CI 1.3–4.1) of being ISUP grade group 5.ConclusionThis trial provides early evidence that PSMA PET/CT assists in the grading of prostate cancer and suggests that the imaging modality is particularly accurate in subpopulations including the elderly and those with palpable disease.

Comparing the Diagnostic Performance of Multiparametric Prostate MRI Versus 68Ga-PSMA PET-CT in the Evaluation Lymph Node Involvement and Extraprostatic Extension

Our research aims to compare the efficacy of PET and MRI for lymph node metastasis and extraprostatic extension in cases with newly diagnosed prostate cancer undergoing radical prostatectomy with extended pelvic lymph node dissection. Thirty-nine cases who underwent radical prostatectomy with pelvic lymph node dissection between June 2015 and January 2020 were included in the study. Patients with gallium (ga-68 Prostate-specific membrane antigen (PSMA) PET) PSMA PET-CT and multiparametric (mp) prostate MRI performed according to PIRADS v2 criteria in our clinic were included. The extraprostatic extension was observed in 16 cases. The sensitivity of MR in detecting extracapsular invasion was calculated as 56.2%, specificity 82.6%, positive predictive value (PPV) 69.2%, negative predictive value (NPV) 73.0%. The sensitivity of PET was 62.5%, specificity 60.8%, PPV 52.6%, NPV 70%. Eleven lymph node metastases were observed in nine cases. The sensitivity, specificity, PPV and NPV of metastatic lymph node detection were; 36.3%, 99.6%, 57.1%, 99.0% for MRI and; 18.1%, 99.4%, 33.3%, 98.8% for PET CT, respectively. Mp prostate MRI showed low sensitivity and high specificity compared to PSMA PET CT in extracapsular invasion evaluation. The sensitivity of both modalities in the detection of metastatic lymph nodes was low.

Diagnostic Utility of Lutetium-177 (Lu 177) Prostate-Specific Membrane Antigen (PSMA) Scintigraphy In Prostate Cancer Patients With PSA Rise And Negative Conventional Imaging.

Prostate cancer is a major worldwide health concern with up to 60% of patients experiencing biochemical relapse after radical treatment. Introduction of prostate-specific membrane antigen (PSMA)-based radiotracers for imaging and therapy had gained increasing attention in recent years. Positron emission tomography (PET) imaging with Ga68 PSMA is the most promising technique, but PSMA-based radiotracers SPECT imaging with low dose of 177Lu-PSMA when PET imaging is not available may also be considered. The goal of the study is to evaluate the sensitivity of 177Lu_psma for detection of metastatic sites in patients with biochemical relapse and negative conventional (MRI, MRS, CT scan and bone scintigraphy) imaging. 26 patients with biochemical recurrence after curative (surgery and/or radiotherapy) therapy, which had previous negative imaging as pelvic CT scan, pelvic MRI, MRS and bone scan, were enrolled in this clinical imaging approach between 2015 and 2017.After injection of 5 mCi (185MBq)177Lu-PSMA-617, diagnostic planar whole body scan and SPECT study was obtained after 3 hours, 24 hours and 72 hours . The images were analyzed visually by an expert nuclear medicine physician for the presence of active regional or distant lesions. Results were then prospectively checked by new CT scan images as a control. A total of 26 patients, with a mean age of 70 years (range: 46 to 89 years) were included in this study. The overall detection rates were 38.5% (10 out of 26 patients). Most common site of detected lesions was lung in 6 patients, abdominal lymph nodes in 2 and mediastinum in another 2 patients. 177Lu-PSMA SPECT scan can help detecting metastatic lesions in more than one third of patients with biochemical recurrence and negative conventional investigations, when 68Ga- PSMA PET is not available.

Assessment of the role of Ga-68 PSMA I&T PET/CT in response evaluation to docetaxel therapy in castration resistant prostate cancer patients

ObjectiveThere have been only few studies investigating the role of PSMA ligands in the therapy response assessment of metastasized castration resistant prostate cancer (mCRPC) cases. In this study we aimed at evaluating the capability of 68Ga- prostate-specific membrane antigen (PSMA) -I&T positron emission tomography/computerized tomography (PET/CT) in the assessment of therapeutic response in patients under docetaxel therapy for prostate cancer (PCa). Material and methodsThe clinical records of all mCRPC patients treated with docetaxel and referred to our department for 68Ga-PSMA I&T PET/CT imaging were retrospectively analysed. Sixteen patients (mean age 69 years, range 52–82 years) with castration-resistant prostate cancer patients receiving palliative docetaxel therapy and had undergone 68Ga-PSMA I&T PET/CT scan were included in the study. 68Ga-PSMA I&T PET/CT imaging was done and prostate specific antigen (PSA) levels were measured at baseline before administration of docetaxel (PET1) and after at least 3 cycles (range 4–12) of chemotherapy (PET2). Patient-based as well as lesion-based comparison of PET2 findings with PET1 findings were done. ResultsThe change (decrease) observed in lymph node and prostate gland/prostatic bed SUVmax values after treatment compared to pretreatment was found to be statistically significant (p=0.033).3/16 patients (19%) were classified as progressive disease (PD), 4/16 (25%) as stable disease (SD), 9/16 (56%) as partial remission (PR) radiologically. An increasing PSA trend (IT) was observed in 4 patients (25%) and a decreasing PSA trend (DT) in 3 patients (18%). Nine patients showed a PSA response of ≥50% (56%). Of the 4 patients showing SD, 3 had IT, 3 had BR. Of the 9 patients who showed PR on PET studies, 8 patients showed BR and 1 patient showed DT. ConclusionImaging with 68Ga-PSMA PET/CT showed great concordance with biochemical response evaluation in terms of PSA levels, especially in patients showing good response to therapy. 68Ga-PSMA PET/CT was also successful in identifying progressive disease in patients showing paradoxical decline in PSA levels.

Role of Early PET/CT Imaging with 68Ga-PSMA in Staging and Restaging of Prostate Cancer

Ga-68 Prostate-Specific Membrane Antigen PET/CT is a new tool for the assessment of prostate cancer. Standard imaging time is 60 minutes post injection of radiotracer. At 60 minutes, there is physiologic accumulation of radiotracer in the urinary bladder which may cause some lesions in its vicinity to be obscured. Our aim is to determine if early imaging at 3 minutes in addition to standard imaging at 60 minutes can improve the detection of PSMA-avid lesions. A retrospective review of 167 consecutive patients was conducted. Overall, 115 patients (68.9%) were ruled to have prostate cancer based on imaging as seen on early or standard PET/CT images. In 106/115 (64%), the lesions were detected on both early and standard imaging; in 8/115 (6.9%), the lesions were only detected on early imaging; in 1/115 (0.6%) the lesion was detected only on standard imaging. The addition of early imaging significantly improved the overall detection rate of PSMA-avid lesions (p = 0.039). The ratio of patients with lesions detected on early imaging but not on standard imaging in restaging group was 7/88 and was higher than that in staging group 1/79 (p = 0.043). We recommend early imaging in addition to the standard imaging in Ga-68 PSMA PET/CT, particularly in patients presenting for restaging of prostate cancer.