Intravascular ultrasound

Intravascular ultrasound (IVUS) is a medical imaging methodology using a specially designed catheter with a miniaturized ultrasound probe attached to the distal end of the catheter. The proximal end of the catheter is attached to computerized ultrasound equipment. It allows the application of ultrasound technology, such as piezoelectric transducer or CMUT, to see from inside blood vessels out through the surrounding blood column, visualizing the endothelium (inner wall) of blood vessels in living individuals.

Procedure

The arteries of the heart (the coronary arteries) are the most frequent imaging target for IVUS. IVUS is used in the coronary arteries to determine the amount of atherosclerotic plaque build up in the vessel wall. IVUS is of particular interest to interventional cardiologists for determining the amount of atheroma in a segment of artery, the area of the vessel lumen, and the area of the vessel wall and outer vessel area (within the adventitia).

Clinical Applications

IVUS is used during angioplasty and stenting procedures. It helps in assessing the lesion that is to be stented, guiding stent placement and expansion, and assessing the result of the intervention. IVUS can also be used to assess non-atherosclerotic coronary artery disease conditions, such as coronary artery aneurysm or coronary dissection.

Advantages

IVUS has the advantage of being able to visualize the vessel in a cross-sectional view. It can measure the vessel lumen diameter, vessel area, plaque area and volume, and the plaque morphology. IVUS is the only method that can measure the plaque burden, vessel remodelling, and the plaque composition.

Limitations

IVUS has a limited penetration depth, which restricts its use in large vessels. It also has a limited resolution, which restricts its ability to accurately measure thin-cap fibroatheromas and small calcium deposits.

See Also

• Angiography
• Cardiology
• Coronary artery disease
• Atherosclerosis