The advantages of two-dimensional (2D) compared with three-dimensional (3D) imaging and reducing scan time in BGO based Positron Emission Tomography/Computed Tomography (PET/CT) scanners remains a matter of discussion. We investigate these parameters for an axial single-field-of view (SFOV) in head and neck cancer using an interleaved 2D and 3D protocol. Each scan pair consists of 4 min, 3 min and 2 min acquisitions on a GE DISCOVERY ST PET/CT scanner. Semi-quantitative parameters are investigated through regions-of-interest (ROIs) drawn around each tumour and associated background area in all scans. It is observed that all tumours are clearly seen regardless of 2D or 3D acquisition mode and scan time duration. 2D scans exhibit greater tumour SUV maximum and tumour/background (T/B) ratio while 3D scans exhibit lower image noise potential. The results suggest 3 min per bed scan time duration is feasible. The conclusion is that there is no distinct advantage of 2D compared with 3D imaging for a SFOV in head and neck caner and that a scan duration of 3 min may be implemented.