Radiographic tests
A reference guide so you know what to expect.
If you are having tests or procedures done at St. Luke's, please
read this before your visit.
Radiographic tests
Radiographic tests
Calcium-Score Screening Heart Scan
This test can help detect atherosclerosis (hardening of the arteries or coronary artery disease) before symptoms appear. It does this by detecting the calcium deposits found in the plaque that causes atherosclerosis in the coronary arteries of the heart. More calcium indicates a greater degree of atherosclerosis and increased risk for heart attack, high blood pressure and other cardiovascular conditions. However, not all forms of atherosclerosis contain large amounts of calcium.
This test is a type of cardic computed tomography (CT), which uses a special kind of X-rays. The procedure is not recommended for pregnant women or people who are having radiation treatments. A type of blood test may be taken before the heart scan. Three electrodes are attached to the patient's chest and connected to an electrocardiogram machine to measure the heart's electrical activity. The patient lies on a table connected to the donut-shaped CT machine. The table moves into the "hole" of the donut and the scanner takes multiple images as the heart beats. The scan only takes a few minutes. A computer develops a calcium score based on the number and density of the calcified plaque areas in the heart's arteries.
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Cardiac Computed Tomography (CT)
This procedure involves taking special X-rays which provide cross-sectional images of the heart and coronary arteries. It is used to evaluate diseases of the aorta (the largest artery in the body) and the pericardium (the membrane-like sac surrounding the heart), as well as tumors or other masses in the heart. Patients may be asked not to eat or drink before the test. A CT often involves injecting a contrast dye into an IV inserted into a vein in the hand or arm. The dye improves computer images of the heart. For the scan itself, the patient lies on a table connected to the CT machine, which resembles a large "donut." At specific intervals, the table may move through the center "hole" of the donut in conjunction with the machine. Patients should lie motionless for the best images. The CT scan usually takes less than 30 minutes. There are generally no side effects of a CT scan, although a small portion of patients may have a reaction to the contrast dye.
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Magnetic Resonance Imaging
(MRI)
An MRI uses a strong magnetic field and radio waves to create three-dimensional images of the inside of the body. There is no radiation involved. A heart MRI may take from 20 minutes to two hours in order to take unique pictures of the heart, its movement and function. An MRI can help detect heart disease, heart attack damage, some congenital heart defects as well as diseases of the aorta (the largest artery in the body) and other large blood vessels.
All watches, jewelry and other metal objects must be removed before the test. The patient should tell the doctor and MRI technician if there are metal objects in his or her body, such as artificial joints. The medical staff should also be aware of any tattoos (some contain metallic ink) or if the patient frequently works with metal or metal shavings. Patients with pacemakers or women in the first trimester of pregnancy are generally not candidates for an MRI.
The patient lies on the MRI table and special pads are placed behind the back and on the front of the chest. Sometimes an IV is inserted into a vein in the hand or arm before the test if dye or medications are required for the test. Sometimes a medication may be injected to make the heart work harder during the MRI.
The table then moves into the center of a large cylinder. Most (closed) MRI machines provide little room for movement once inside because movement can distort MRI images. Some people may find this somewhat claustrophobic and may require sedation before the test. The machine makes loud thumping noises. Some facilities offer earplugs or headphones playing music to muffle the sounds. When inside the machine, the patient can be seen and heard by the technician. The patient may be asked to hold his or her breath at certain times to ensure clear images. Heart rhythm and blood oxygen levels may be monitored during the test.
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Magnetic Resonance Angiography
MRA is used to take images of the coronary arteries to diagnose narrowing or blockages from coronary artery disease. It is also useful for diagnosing and treatment planning for disorders of the aorta (the largest artery in the body). MRA may also be used to check for disorders such as blood clots in other arteries of the body. It is sometimes used in place of or in conjunction with angiography or certain ultrasound tests. It also serves as an alternative in some cases to a transesophageal echocardiogram and cardiac computed tomography.
MRA utilizes the same technology as magnetic resonance imaging - magnetic fields and radio waves. It provides images of blood flow as well as blood vessels. It is a helpful tool for surgical planning and as an alternative for people who are not candidates for angiography. A contrast dye may be injected through an IV to improve MRA images, but it is safe for people allergic to the iodine solutions used in other tests. The MRA procedure lasts from 10 minutes to an hour.
All watches, jewelry and other metal objects must be removed before the test. The patient should tell the doctor and MRA technician if there are metal objects in his or her body, such as artificial joints. The medical staff should also be aware of any tattoos (some contain metallic ink) or if the patient frequently works with metal or metal shavings. Patients with pacemakers are generally not candidates for an MRA. Check with the physician about eating, drinking or taking medications before the test.
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