Jason Trang1, David McHarg2, Brian Owler1,3. 1. Department of Neurosurgery, Sydney Adventist Hospital, Sydney, New South Wales, Australia. 2. Department of Radiology and Nuclear Medicine, Sydney Adventist Hospital, Sydney, New South Wales, Australia. 3. Discipline of Child Health and Paediatrics, Children's Hospital at Westmead, The University of Sydney, Sydney, New South Wales, Australia.