Gallium-68-THP PSMA

Objectives: To assess the safety and clinical impact of a novel, kit-based formulation of ⁶⁸Ga-THP PSMA positron emission tomography/computed tomography (PET/CT) when used to guide the management of patients with prostate cancer (PCa). Methods: Patients were prospectively recruited in to one of: Group A: high-risk untreated prostate cancer; Gleason score >4+3, or PSA >20 ng/mL or clinical stage >T2c. Group B: biochemical recurrence (BCR) and eligible for salvage treatment after radical prostatectomy with two consecutive rises in prostate specific antigen (PSA) with a three month interval in between reads and final PSA >0.1 ng/mL or a PSA level >0.5 ng/mL. Group C: BCR with radical curative radiotherapy or brachytherapy at least three months prior to enrolment, and an increase in PSA level >2.0 ng/mL above the nadir level after radiotherapy or brachytherapy. Patients underwent evaluation with PET/CT 60 minutes following intravenous administration of 160±30 MBq of ⁶⁸Ga-THP PSMA. Safety was assessed by means including vital signs, cardiovascular profile, serum haematology, biochemistry, urinalysis, PSA, and Adverse Events (AEs). A change in management was reported when the predefined clinical management of the patient altered as a result of ⁶⁸Ga-THP PSMA PET/CT findings. Results: Forty-nine patients were evaluated with PET/CT; 20 in Group A, 21 in Group B and 8 in Group C. No patients experienced serious AEs discontinued the study due to AEs, or died during the study. Two patients had Treatment Emergent AEs attributed to ⁶⁸Ga-THP-PSMA (pruritus in one patient and intravenous catheter site rash in another). Management change secondary to PET/CT occurred in 42.9% of all patients; 30% in Group A, 42.9% in Group B and 75% in Group C. Conclusion: ⁶⁸Ga-THP PSMA was safe to use with no serious AE and no AE resulting in withdrawal from the study. ⁶⁸Ga-THP PSMA PET/CT changed the management of patients in 42.9% of the study population, comparable to studies using other PSMA tracers. These data form the basis of a planned Phase III study of ⁶⁸Ga-THP PSMA in patients with prostate cancer.

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.