Abstract
1414
Objectives Prostate specific membrane antigen (PSMA) is a cell surface protein, which is expressed at high levels in prostate cancer cells. It provides a promising target for prostate carcinoma specific imaging and therapy. Recently labelling procedures have been developed to label PSMA ligands with 68Gallium (68Ga) which makes them suitable for PET imaging. Our initial experience with 68Ga-PSMA-PET/CT suggests that this novel method can detect prostate carcinoma relapses and metastases with improved contrast compared to 18FECH-PET/CT. The aim of this study was to investigate the normal tissue uptake in patients.
Methods 15 patients underwent [68Ga]-PSMA-PET/CT. The mean and the maximum standardized uptake values (SUVmean/SUVmax) of brain, lacrimal glands, parotid glands, submandibular glands, lungs, mediastinal blood pool, liver, spleen, pancreas head, bowels and kidneys were determined one hour after intravenous injection. Furthermore, the uptake was measured in 26 tumor lesions.
Results SUVmean/SUVmax mean values (and standard deviation) were in brain 0.2/0.3 (±0.3/±0.3), lacrimal glands 4.4/8.9 (±1.0/±3.5), parotid glands 7.7/17.1 (±1.4/±5.0), submandibular glands 8.1/19.0 (±1.6/±4.9), lungs 0.5/0.9 (±0.4/±0.4), mediastinal blood pool 0.9/1.3 (±0.2/±0.3), liver 3.8/7.1 (±0.7/±2.4), spleen 4.8/8.9 (±2.0/±3.9), pancreas head 1.6/2.9 (±0.7/±1.2), bowels 4.3/9.2 (±1.3/±3.0) and kidneys 19.1/48.8 (±3.1/±13.0). Tumor- SUVmean/SUVmax mean values (and standard deviation) were 4.4/8.1 (±1.3/±3.3).
Conclusions This study presents for the first time the normal uptake values of [68Ga]-PSMA-ligands in healthy tissue. It is remarkable only in salivary glands, lacrimal glands, liver, spleen, parts of bowels and kidneys. Our analysis helps to distinguish between pathologic and healthy tissue in patients with PSMA-PET imaging due to metastatic prostate cancer