1. Section of Radiology, Department of Surgery, Radiology, Anaesthetics and Intensive Care, Faculty of Medical Sciences, University of the West Indies, Mona Campus, Kingston, Jamaica
2. Department of Clinical Surgical Sciences, Faculty of Medicine, University of the West Indies, St. Augustine Campus, St. Augustine, Trinidad and Tobago
3. Section of Anatomy, Basic Medical Sciences, University of the West Indies, Mona Campus, Kingston 7, Jamaica
4. University Surgical Unit, Southampton General Hospital, Southampton SO16 6YD, UK