MRI in multiple vascular lesions: identification of the ruptured malformation.

4 patients were recently admitted for subarachnoid haemorrhage with multiple vascular lesions. 3 of them presented with multiple aneurysms, and one with an aneurysm associated with an arteriovenous malformation. In these 4 cases identification of the ruptured lesion was difficult in spite of clinical examination, CT scan, and complete panangiography; on magnetic resonance imaging (MRI) was found a signal hyperintensity, mainly on T2 weighted views, corresponding to blood clots around the ruptured aneurysm. This signal hyperintensity was completely absent in the vicinity of the associated vascular lesion, which appeared only as a signal void corresponding to the blood flow inside the unruptured lesion. Therefore MRI can be used in such cases to identify the ruptured lesion, so permitting the choice of the best approach and strategy of treatment.