1. Ultrasound Department, Mid Yorkshire Hospitals NHS Trust, Pinderfields General Hospital, Aberford Road, Wakefield WF1 4DG, UK;
2. Radiology Department, Mid Yorkshire Hospitals NHS Trust, Pinderfields General Hospital, Aberford Road, Wakefield WF1 4DG, UK;
3. School of Healthcare, University of Leeds, Baines Wing, Leeds LS2 9JT, UK