This is a prospective observational registry with intent to detect the prevalence of intracranial aneurysms with contrast-enhanced MR angiography (CE-MRA) at 1.5T, and to determine the risk factors such as high blood pressure and cigarette smoking relating to intracranial aneurysms.

Intracranial aneurysms are common and have been reported increased incidence rate because of the widespread use of high-resolution imaging techniques. They are clinically important because of the life-threatening rupture and hemorrhage. Early detection and diagnosis is the key of treatment. Contrast-enhanced MR angiography (CE-MRA), as a simple, sensitivity and noninvasive method, is playing an important role in Vascular Imaging. CE-MRA has been an accuracy modality for intracranial aneurysm at most centers and proved the high sensitivity and accuracy comparing with DSA. Therefore, we use CE-MRA at 1.5T as a tool of epidemiological investigation of intracranial aneurysms.

In retrospective analysis, conventional risk factors for intracranial aneurysms include hypertension, hyperlipidemia, diabetes mellitus (DM), smoking history, and family history, etc. However, retrospective analysis probably gives an underestimation or overestimation of the actual results. Prospective analysis will get accurate data on the risk factors relating to intracranial aneurysms

Inclusion Criteria:

• Aged 20 to 80 years
• Willing to undergo study procedures
• Who are fully informed about the study and have signed the informed consent form

Exclusion Criteria:

• History of intracranial aneurysm
• History of intracranial tumor
• History of cerebral infarction
• Acute stroke
• Require emergency treatment
• Contraindication for MRI examination
• Severely impaired renal functions
• Known anaphylactic reaction to MR contrast media
• Pregnancy or nursing

People coming to Changhai hospital to get health check or consult docter, undergoing cerebral CE-MRA, and according with the criteria were recruited. Assuming an 8 percent prevalence of intracranial aneurysm in the general population and using a two-sided alpha value of 0.05, we estimated that 4000 persons would need to be enrolled for the study.