That includes atherosclerosis , a disease in which fat builds up inside the wall of your arteries (blood vessels that deliver oxygen-rich blood throughout your body). Other things that can come into play:

Several things, including your medical history and lifestyle, can increase your odds of a brain aneurysm.

Diagnosis

Several types of scans and tests can be used to figure out whether you have a brain aneurysm. They include:

CT scan: This exam creates images of your brain. You will lie on a table that slides into a CT scanner. A technician will inject contrast dye into one of your veins to make it easier to see the blood flow and spot aneurysms in your brain.

MRI: This exam is similar in that you lie on a table that slides into a scanner. The MRI uses magnetic field and radio waves to create detailed images of your brain and blood vessels. MRIs and CT scans can detect aneurysms larger than 3 to 5 millimeters.

The following tests are more invasive than CT or MRI scans. But they could give you and your doctors with a more complete picture of what’s going on:

Angiogram: This test, considered the most reliable way to detect aneurysms, shows the weak spots in your blood vessels.

During the test, you lie on an X-ray table, and you will be given something to numb any pain.

Your doctor will insert a small flexible tube through a blood vessel in the leg. She will guide that tube, called a catheter, into the blood vessels in your neck that reach the brain.

She will inject a contrast dye into you, and X-rays will be taken that show all the blood vessels in the brain. This gives your doctor a map of your blood vessels, pinpointing the aneurysm.

Cerebrospinal fluid test: Your doctor may order this test if she suspects that an aneurysm may have ruptured.

You’ll be given something to block any pain. A technician will inject a needle into you to draw spinal fluid. That fluid is tested to see whether it contains blood, which could indicate that an aneurysm has ruptured.