Treating Cardiovascular Diseases in Wisconsin and Northern Illinois
Radiographic testing is a general term that refers to several different techniques for visualizing the body’s internal structures. Images produced by radiographic tests can be examined on computer monitors, printed or recorded electronically.
Although many radiographic tests involve radiation, they are considered safe because their dosages are very low. (However, they are generally not recommended for women who are pregnant or breastfeeding.)
How Do Radiographic Tests Work?
With many radiographic tests, X-ray beams (electromagnetic radiation) are passed through your body. Some of the X-rays are absorbed by your internal structures; the remaining are transmitted to a detector and sent to a monitor or recorded.
Different parts of your body absorb X-rays differently. Your bones are the most absorbent, which is why they appear white on radiograph images. Fat and other soft tissues are less absorbent, which is why they look gray. Air is the least absorbent, which is why lungs appear black.
Computed tomography (CT) scanning, also called computerized axial tomography or CAT scanning, is an imaging procedures that uses X-ray images and a computer to generate cross-sectional views, or slices, of your body. This test provides greater clarity and detail than traditional X-rays.
Magnetic resonance imaging (MRI) does not use X-rays. Instead, it uses strong magnetic fields and radio waves to produce cross-sectional images of organs and internal structures. MRI signals vary depending on the water content and magnetic properties of different parts of the body, allowing doctors distinguish between different tissues and substances.
Several Types of Radiographic Tests
Doctors use several different radiographic teststo diagnose various heart conditions and disorders:
- A calcium-score screening heart scan is a type of CT scan thathelps doctors detect calcium deposits in your coronary (heart) arteries.This testis also known as a coronary calcium scan, calcium score test or a cardiac CT for calcium scoring.
Calcium is one of several materials found in plaque, a substance that can build up in your arteries, causing them to harden and narrow. When plaque builds up in your coronary arteries, it can lead to coronary artery disease and increase your risk for a heart attack. Learn the signs and symptoms of coronary artery disease.
A calcium-score test is one of the most sensitive approaches for detecting coronary artery disease before symptoms develop. However, it only detects hard, calcified plaque; it does not detect soft plaque. If calcium is detected, you will receive a score estimating the extent of your coronary artery disease. This will help your doctor devise a treatment plan.
During a calcium-score test, you lie on a table that moves inside a donut-shaped scanner that captures multiple images of your heart. An EKG monitors you heart’s electrical activity. The test takes about 10 to15 minutes.
Your doctor may ask you to avoid caffeine and smoking for 4 hours prior to the test. You may also be asked to undergo a lipid analysis before the test, which requires a 12-hour fast.
Chest X-rays help doctors see whether your heart is enlarged, which can be a sign of heart failure or if fluid has built up in your lungs. Chest X-rays also help doctors evaluate the placement pacemakers, defibrillators and catheters.
No special preparations are necessary for chest X-rays. Allow about a half hour for your appointment.
Learn more about radiation from your X-ray exam. (PDF, 36 KB)
- A chest X-ray uses a very small amount of radiation to produce an image of the structures inside the chest (your heart, lungs, blood vessels and bones). A chest X-ray is also known as CXR or chest radiography.
- Cardiac computed tomography uses advanced CT technology with contrast dye and special X-rays to create 3-D images of the moving heart, its circulation and great vessels (aorta and pulmonary arteries).
This testhas many names: CT coronary angiography, coronary CT angiography, CT angiography, CTA, cardiac CT, cardiac CAT scan, coronary CTA, multi-slice computed tomography or MSCT.
After the contrast is injected and reaches your heart, the CT scanner takes thousands of cross-sectional views, or slices, of your heart. The scanner then puts the pictures back together to form a 3-D image of your heart.
Cardiac computed tomographyhelps doctors detect plaque in coronary arteries, one of the signs and symptoms of coronary artery disease. Unlike a calcium-score screening, cardiac computed tomographyis able to detect soft plaque. It also helps doctors detect aneurysms or a pulmonary embolism and plan for bypass surgery.
Cardiac computed tomography is noninvasive, meaning it does not require surgery or the insertion of catheters. Compared to cardiac catheterization, cardiac computed tomographyis performed more quickly and with potentially less risk, discomfort and recovery time. However, catheterization may be the preferred option if there is a potential need for stenting.
During cardiac CT coronary angiography, you lie very still on a table that moves inside a donut-shaped scanner. X-rays pass through your body and are picked up by detectors in the scanner, which produces 3-D images on a computer screen. The test is performed in hospitals and outpatient offices.
- Magnetic Resonance Imaging (MRI) creates moving images of the heart throughout its pumping cycle, helping doctors evaluate the anatomy and function of the heart, great vessels (aorta and pulmonary arteries) and the sac surrounding the heart.
Heart specialists use this test to help detect many conditions, including:
o Pulmonary artery disease
o Some forms of congenital heart disease
o Thoracic aortic disease
Because MRI uses powerful magnets, people who undergo this exam should be free of metallic or magnetic items. Tell your doctor if you have implanted devices, such as stents, a pacemaker, a defibrillator, a clip in a blood vessel in the brain, a choclear (ear) implant, insulin pump, narcotic pump or nerve stimulator for back pain.
During this test, you will lie on a platform bed that moves into the MRI scanner unit, which is a long tube that is open at both ends. An intercom system allows you to talk to scanner operators during the test.
An EKG will monitor your heart’s electrical activity. Most likely, an intravenous (IV) line will be inserted into a vein in your arm to administer contrast dye. During the scanning, you may hear loud noises, which can be muffled with headphones or earplugs provided for you. Depending on the extent of the imaging needed, the scan make take about 30 to 75 minutes.
If you have a fear of closed spaces, you may be sedated for this exam. To avoid nausea with the sedation, avoid all solid food for 6 hours prior to the exam. You may have clear liquids up to 2 hours before receiving the sedative. Arrange for someone to take you home.
If you are not sedated, you may resume your usual activities and diet after the exam.
- MRI adenosine stress testis a pharmacological MRI. It is for people who are unable to exercise or cannot increase their heart rate adequately. This test can help doctors determine if you are getting enough blood to your heart when you are active compared to when you are resting.
During the test, you will receive a small amount of medication (usually adenosine) to increase blood flow to your heart as if you were exercising. A small amount of dye will be injected into a vein when you’re resting and after you receive the adenosine. An EKG will monitor your heart’s electrical activity. Your heart rate and blood pressure will also be monitored.
The MRI scanner takes pictures of the dye as it passes through your heart muscle, creating images of your heart. The test itself may take about 45 minutes. Allow at least 2 hours for your appointment.
To prepare for this test, avoid all products containing caffeine for 24 hours before the test. Your doctor may ask you to stop taking your heart medications on the day of the test. Also, do not smoke, eat or drink, except for small sips of water with your other medications on testing day. Bring a copy of all medications with you to your appointment. Talk to your doctor if you have diabetes for special instructions.