SPECT-CT Imaging with 99mTc-PSMAin Patients with Recurrent Prostate Cancer

Abstract

Background: Prostate-specific membrane antigen (PSMA) is a cell surface glycoprotein with a large extracellular domain with overexpression of the prostatic tumour cells. Several small molecules of PSMA ligands of inhibitors binding to the active site of PSMA were developed. [ 99m Tc]Tc-PSMA-T4 is a new radiopharmaceutical (Polatom) for imaging loco-regional metastases and/or local relapse in patients with prostate cancer.The purpose of this work was to evaluate the clinical application of SPECT-CT imaging with [ 99m Tc]Tc-PSMA-T4 in patients with recurrent prostate cancer.Material and methods: Thirty-six patients with prostate cancer, aged 60-80 years with biochemical relapse of PSA (ranged from 0.1 to 73 ng/mL) were included. Three patients were studied after tru-cut biopsy, hormonal and cytoreductive radiotherapy and 33 patients out of 36 -after radical treatment (total prostatectomy or definitive radiotherapy of the tumour). All of them underwent whole-body imaging examinations with subsequent target SPECT-CT studies of the pelvis, abdomen and/or chest, 1-3 hrs post i.v. administration of [ 99m Tc]Tc-PSMA-T4. The average activity dose was 6.3 MBq/kg in a man of 70 kg. A Dual-head SPECT-CT gamma camera with a low dose CT scan (Symbia T2, Siemens) was used. The images were interpreted based on all other clinical and radiological data. Follow-up could be conducted in 11/36 patients during that period.Results: Normal biodistribution of the radiopharmaceutical with high activity background was observed in the liver, spleen, kidneys, lacrimal and salivary glands, bowels and urinary bladder. Positive imaging for local relapse in the prostate bad was imaged in 21 patients, lymph node metastases -in 16 cases, bone lesions -in 10 cases, pulmonary metastases -in 2 cases, hepatic lesions were visualised in one of them and in another -adrenal suprarenal metastasis with intensive tracer uptake significant for overexpression of PSMA. There was a suspicion for local recurrences in 4 patients with negative MRT studies who were followed up. In 3 cases, previously treated bone metastases were partially negative without tracer uptake, only some progressive bone lesions were positive. Five patients were with negative results. Sensitivity was 84.37% (27/32), specificity -100% (4/4) and accuracy -86.11% (31/36). Conclusions:In conclusion SPECT-CT imaging with [ 99m Tc]Tc-PSMA-T4 could be applied in patients with prostate cancer for the diagnosis of recurrent disease to determine personalized treatment for each patient. Specific uptake of this tracer, depicted by SPECT-CT images has clinical importance of identifying and assessing PSMA expression before consideration of Radio Ligand Therapy (RLT) with [ 177 Lu]Lu-PSMA. SPECT-CT imaging with [ 99m Tc]PSMA is promising and reliable nuclear medicine approach to monitoring therapeutic effect after treatment and for restaging of the disease.

Initial Experience of Clinical Use of [99mTc]Tc-PSMA-T4 in Patients with Prostate Cancer. A Pilot Study

“…To date, there are only a few publications that have indicated the potential clinical use of technetium-99m labeled PSMA [24,[30][31][32]. Here, we have reported our initial clinical experience with the use of [ 99m Tc]Tc-PSMA-T4 radiolabeled ligand in subjects with prostate cancer, which was initially and recently described by Sergieva et al [34,35]. The potential broader use of technetium ( 99m Tc) is suggested, because this radiotracer has the ideal nuclear properties of energy (140.5 keV photon) and half-life (6 h) and it is ideal for routine clinical use in all nuclear medicine departments equipped with standard a SPECT/CT gamma camera.…”

“…The potential broader use of technetium ( 99m Tc) is suggested, because this radiotracer has the ideal nuclear properties of energy (140.5 keV photon) and half-life (6 h) and it is ideal for routine clinical use in all nuclear medicine departments equipped with standard a SPECT/CT gamma camera. Additional use of convenient commercial technetium generators offers the possibility of wide clinical use of 99m Tc labeled ligand any time of the working day of the nuclear medicine department [30][31][32]34,35].…”

“…[ 99m Tc]Tc-PSMA-T4 is rapidly eliminated from the blood, so the images taken 1 h after injection of the radiotracer are of good quality. The activity accumulated in the blood cells is below 5% regardless of time after injection [33][34][35]. The images obtained after 3-4 h and 5-7 h are very similar in terms of clinical utility.…”

“…Investigators from the National Center for Nuclear Research Radioisotopes Centre POLATOM developed a new radioligand, PSMA-T4 (Glu-CO-Lys-L-Trp-4-Amc-HYNIC) (C 37 H 49 N 9 O 10 with a molecular weight (MW) of 779.36 g/mol), which potentially can be used in the diagnosis of PCa patients [33]. The first clinical use of this radiopharmaceutical in humans was presented by Sergieva et al [34]; the same team also reported its clinical use in patients with recurrent PCa [35].…”

Molecular Imaging in Primary Staging of Prostate Cancer Patients: Current Aspects and Future Trends

“…Therefore, different PSMA inhibitors were labeled with 99m Tc [ 134 , 135 , 136 , 137 , 138 ]. [ 99m Tc]Tc-PSMA scintigraphy has been investigated for different purposes, such as biochemical recurrence, primary staging, and radio-guided surgery [ 139 , 140 , 141 , 142 , 143 ].…”