MRA OF INTRACRANIAL ANEURYSMS

Most intracranial aneurysms are located in the circle of Willis. They occur in 5-6% of the general population. Patients with intracranial an eurysm either present catastrophically with rupture of the aneurysm ha ve aneurysms that are incidentally discovered. Prognosis is drasticall y different in each case, with a greater than 50% incidence of death i f there is a rupture of the aneurysm. On the other hand, the surgical or endovascular mortality following treatment of an unruptured aneurys m is minimal, with good patient neurological outcome. In the appropria te clinical setting, it is important to find a screening study that ca n detect a cerebral aneurysm so that definitive cerebral angiography c an be performed The combination of magnetic resonance imaging (MRI) an d magnetic resonance angiogram (MRA) can detect an aneurysm in 60-85% of cases. This screening test adds a few minutes of scanning time to t he average MR examination. Magnetic resonance angiography techniques c ontinue to improve with better gradients, enhanced sequences to detect flow and reduce flow-related artifacts, shorter echo times with possi ble use of echo-planar (short scanning time) techniques, and improved imaging matrix, and they may, in conjunction with computed tomographic angiography (CTA), become a reliable non-invasive technique for detec tion of intracranial aneurysm. (C) 1997 Wiley-Liss, Inc.