CT features of mycotic aneurysms

To describe CT features of mycotic aneurysms. We have retrospectively checked 10 patients diagnosed with mycotic aneurysm. Three revealed previously treated arteriosclerotic aneurysms, one was diabetic and had undergone a reno pancreatic transplant,and another presented advanced HIV infection. They al presented fever syndrome and eight exhibited leucocytosis. Mycotic aneurysm diagnosis was made by means of CT findings, clinical examination and positive hemo culture in all cases. Anatomopathological findings were available as confirmation for all four surgically treated patients. The CT scan was performed during arterial phase with spiral acquisition, without contrast and with endo venous administration of a contrast medium. Saccular aneurysms were found in seven patients (double aneurysms in the case of two), with seven of these being abdominal aneurysms (one retrocrural aortic,three infra renal aortic, and three iliac arteries) and two thoracic (aortic arch). In all three remaining patients, there was a pre-existing arteriosclerotic aneurysm (fusiform) and only incipient changes were observed in the adjacent fat. Perianeurysmatic soft-tissue was was noted in eight cases. Only two patients presented signs of tear (peri aneurysm hematoma and/or with contrast extravasation). In three cases, the calcium ring was disrupted. In two patients, absences were observed in other locations. In none of the cases was there gas in the aneurysm wall. Mycotic aneurysm is a rate entity, but must be considered in the evaluation of septic patients since it demands early diagnosis and treatment. In such patients, a CT finding of saccular aneurysm with adjacent soft-tissue mass, and associated with a positive hemo culture, is highly suggestive of this pathology. (Author) 9 refs