The study goal is to investigate how the simulated reduction of injected radiotracer affects PET image quality and quantification in whole-body PET/MR in patients with oncologic findings. PET data of fifty-one patients was reconstructed with 4, 3, 2 and 1 minute/bed time interval. Image quality parameters were analyzed. As expected, the image quality decreases with shorter PET image acquisition times. Besides the two key factors acquisition time and injected activity, the image quality is influenced by the BMI. A lower BMI results in better image quality parameters. 2 minutes acquisition time per bed is sufficient to provide accurate lesion detection.