Objective: The primary objective is to evaluate the uptake of 68Ga-PSMA in locally advanced, recurrent and metastatic ACC/SDC by performing 68Ga-PSMA-PET/CT scans. The secondary objectives are to calculate the SUV tumor-to-background ratio and tumor-to-'healthy salivary gland tissue' ratio. To correlate the SUV to the degree of immunohistochemical PSMA expression of the primary tumor on archival tissue, and to establish whether new metastatic lesions are found by 68GA-PSMA-PET/CT imaging.