CT (computed tomography) angiography (CTA) is an examination that uses x-rays to visualize blood flow in arterial and venous vessels throughout the body, from arteries serving the brain to those bringing blood to the lungs, kidneys, and arms and legs. CT combines the use of x-rays with computerized analysis of the images.

Magnetic resonance imaging (MRI) is a method of producing extremely detailed pictures of body tissues and organs without the need for x-rays. The electromagnetic energy that is released when exposing a patient to radiofrequency waves in a strong magnetic field is measured and analyzed by a computer, which forms two- or three-dimensional images that may be viewed on a TV monitor. MR angiography (MRA) is an MRI study of the blood vessels.

Ultrasound (US) imaging, also called ultrasound scanning or sonography, is a method of obtaining images from inside the human body through the use of high frequency sound waves. The reflected sound wave echoes are recorded and displayed as a real-time visual image. Ionizing radiation (x-rays) are not involved in ultrasound imaging.

Ultrasound is a useful examination tool for many of the body's internal organs, including the heart, liver, gallbladder, spleen, pancreas, kidneys, and bladder. Because ultrasound images are captured in real-time, they can show movement of internal tissues and organs, and enable physicians to see blood flow and heart valve functions.

How should I prepare for the procedure?
Depending on the part of the body to be examined, you may be asked to take only clear liquids by mouth before CTA. You may be asked whether you have asthma or any allergies to foods or drugs, and what medications you are currently taking. If you are pregnant, you should inform the technologist before the procedure. You probably will not have to undress if you are undergoing an exam of the head, neck, arms or legs but you will have to remove any jewelry, hair clips, dentures and the like that could show up on the x-rays and make them hard to interpret

The magnetic field used for MRA will pull on any iron-containing object in the body, such as a heart pacemaker, intrauterine device, vascular access port, metal plate, pins, screws or staples. You will be given a questionnaire to answer regarding these issues. The radiologist or technologist should know about any such item and also whether you have ever had a bullet in your body, whether you ever worked with metals, or if you have had a joint replacement. If there is any question, an x-ray can be taken to detect metal objects.