An aortic aneurysm is an abnormal widening or bulging of part of the aorta, the body’s largest artery, which carries blood from the heart down through the chest and abdomen. Aneurysms most commonly form in the abdominal aorta (an abdominal aortic aneurysm, or AAA) but can also develop in the thoracic aorta, which runs through the chest. Studies suggest that abdominal aortic aneurysms occur in roughly 4 to 8 percent of men over age 65, with thoracic aneurysms substantially less common. Most aneurysms are slow-growing, cause no symptoms, and are identified incidentally on imaging done for unrelated reasons.
The clinical concern with an aneurysm is the risk that it will continue to grow and eventually rupture, which is a medical emergency. The risk of rupture depends primarily on size — small aneurysms (less than 4 centimeters across in the abdomen) carry very low risk, while larger aneurysms (greater than 5 to 5.5 centimeters) are usually evaluated for surgical or endovascular repair. Risk factors include age, male sex, a history of smoking, high blood pressure, and a family history of aneurysm. Many aneurysms are stable for years, and the standard approach for smaller ones is periodic imaging to confirm they remain unchanged.
MRI is well-suited to evaluating aortic aneurysms because it provides detailed three-dimensional images of the aorta and surrounding structures without ionizing radiation, which matters when monitoring a finding across years. A whole-body MRI can identify a previously unknown aneurysm, characterize its size and shape, and provide a baseline against which future scans can be compared. Patients who would benefit from related context can read the companion entry on brain aneurysm, our blog post on what causes an enlarged heart, or learn more about the Whole Body Scan at MRI Wellness.
Frequently Asked Questions #
Is an aortic aneurysm cancer? #
No. An aneurysm is a structural change in the wall of a blood vessel, not a malignant growth. It does not become cancer.
Do I need surgery? #
Most small aneurysms are monitored with periodic imaging. Surgical or endovascular repair is generally considered for larger aneurysms (typically greater than 5 to 5.5 centimeters in the abdomen) or for aneurysms that are growing rapidly.
What causes an aortic aneurysm? #
Risk factors include age, male sex, smoking history, high blood pressure, atherosclerosis, and a family history of aneurysm. Genetic conditions affecting connective tissue, such as Marfan syndrome, also raise risk.
Should I change my activities if I have one? #
Most patients with small, stable aneurysms continue their normal routine. Your physician may recommend avoiding very heavy lifting or extreme blood-pressure spikes. Managing blood pressure and quitting smoking are the most impactful steps.
How often should it be imaged? #
The interval depends on size. Smaller aneurysms may be checked every 12 to 24 months; aneurysms approaching the surgical threshold are imaged more frequently. Your physician will recommend the right cadence for you.
References #
- U.S. Preventive Services Task Force. Final Recommendation Statement — Abdominal Aortic Aneurysm: Screening. uspreventiveservicestaskforce.org.
- American College of Radiology. ACR Appropriateness Criteria — Nontraumatic Aortic Disease. acr.org.
- Cleveland Clinic. “Aortic Aneurysm.” my.clevelandclinic.org.
- Radiopaedia. “Aortic aneurysm.” radiopaedia.org.
