The detection rate of intracranial aneurysms has increased with the improved availability of non-invasive imaging methods. Moreover, persons who have relatives with intracranial aneurysms increasingly demand imaging to rule out aneurysms. To deal with these problems, radiologists require basic knowledge regarding the detection and treatment of unruptured intracranial aneurysms. The prevalence of aneurysms in the normal population is 2?-?3?%. It increases to 4?-?10?% in persons with one relative with an aneurysm and to about 20?% in persons with two relatives with an aneurysm. The average natural rupture risk is estimated to be 5?% within 5 years of detection. In the individual case it depends on several variables that are discussed here. According to the literature, the risk of endovascular aneurysm treatment is about 5?%. On the basis of these data, the benefit of MRA screening needs to be discussed individually with the patient.
