Definition: Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.
Input: Abstract: CT scans were obtained in five patients who presented with abdominal pain and were found to have an abdominal aortic aneurysm without evidence of hypovolaemia. A periaortic haematoma and evidence of a rupture was found on scanning in three of the patients and confirmed at immediate operation. A retrospective diagnosis of rapidly expanding (acute) aneurysm was made in the other two patients in whom no other pathology was found at early elective operation. CT scanning is useful in differentiating small well-controlled ruptures from rapidly expanding aneurysms.

Differentiation of ruptured aortic aneurysm from acute expansion by computerised tomography.