The Chinese Cerebral Aneurysms Survey is a continuing prospective study among middle-aged and older individuals (35 - 75 years) that aims to determine the prevalence of cerebral intracranial aneurysms in the general population with MRA at 3.0 Tesla (T).

Cerebral intracranial aneurysms are common. In angiographic and autopsy studies, estimates for prevalence vary between 0.2 and 9.9 percent. The methods used to detect the aneurysms markedly influenced the proportion of aneurysms. Retrospective autopsy studies probably give an underestimation and prospective angiography studies an overestimation of the actual prevalence. Accurate data on the prevalence of intracranial aneurysms are essential in evaluating the results of screening programs for aneurysms in general population.

During the past decade, MRA, as a preferred accuracy modality for noninvasive intracranial vascular imaging at most centers, is playing an increasing role in the evaluation of patients suspected of having intracranial aneurysms. In recurrent study, we have tested that MRA at 3T has excellent sensitivity, accuracy, and correlation with DSA and is comparable to catheter cerebral angiography for the evaluation of patients with intracranial aneurysms (Stroke, in press). Therefore, we examined trends in intracranial aneurysm prevalence with the use of MRA at 3.0T to determine the true prevalence of cerebral intracranial aneurysms in the general middle-aged or elder population.

Inclusion Criteria:

• Native inhabitants lived in a defined area sites in China
• Aged 35-75 years

Exclusion Criteria:

• Less than 35 years old or more than 75 years old
• Incompetent patient who cannot give consent for routine MR Angiography and his/her surrogate decision maker is not available
• Any patients with a contraindication to having a standard MRI examination, such as phase maker, orbital metallic foreign body, etc.

The investigators recruited 4500-5000 native inhabitants aged 35-75 years lived in China according to China census-tract data from the year 2005. The gender was accordance with China census-tract data, and the population aged 35-75 years has a higher incident of intracranial aneurysm in the literature. Assuming an 8 percent prevalence of intracranial aneurysm in the general population and using a two-sided alpha value of 0.05, the investigators estimated that 4500-5000 native inhabitants would need to be enrolled for the study.