Features of the physiological distribution of <sup>68</sup>Ga-PSMA and its importance in the differential diagnosis of metastatic lesions of lymph nodes in patients with prostate cancer

Abstract

Introduction. The appearance of new radiopharmaceuticals based on prostate-specific membrane antigen has significantly increased the accuracy of prostate cancer diagnosis. The physiological accumulation of 68Ga-PSMA in the sympathetic ganglia is important in the diagnosis of metastatic lesions of the lymph nodes. Erroneous interpretation of images can lead to an incorrect choice of tactics for the treatment of prostate cancer.Purpose: improving the diagnosis of prostate cancer with the help of updated data on the physiological accumulation of 68GaPSMA. Identify the sources of potential errors in the interpretation of PET/CT with 68Ga-PSMA.Materials and methods. In order to stage the verified prostate cancer, PET was performed in our center/CT with 68Ga-PSMA in 109 men. All patients were divided into groups by the level of prostate-specific antigen, Gleason sum, and d’Amico.Results. In all patients, we observed the accumulation of RFP in the cervical, abdominal and presacral ganglia. The capture level of the radiotracer was in the range of SUV=1,6–2,3 (median SUV=1,9). In the control PET/CT study after treatment, the accumulation of RFP in the cervical, abdominal and presacral ganglia remained at the same values, which made it possible to identify the detected changes as a variant of the physiological norm.Conclusions. It is necessary to take into account the peculiarities of the physiological distribution and accumulation of radiotracer in organs and tissues, in particular, the capture of 68Ga-PSMA by sympathetic ganglia. This will avoid false-positive cases when describing PET-CT images and will make it possible to increase the informative value of the method.