Cardiac CT (computed tomography)
Massachusetts General Hospital Imaging provides Cardiac CT (computed tomography) imaging services in a caring environment using the latest technology and radiation-dose-reduction techniques, and every scan is interpreted by a cardiac-imaging specialist.
Massachusetts General Hospital Imaging provides cardiac CT imaging on the Mass General main campus. Our staff places priority on making your journey through the imaging process comfortable, safe, and successful. All images are read by a cardiac-imaging specialist with additional expertise in CT.
Cardiac CT overview
- A CT scanner rotates to take X-ray images from different angles all around your body. A computer puts these images together to form detailed, two-dimensional pictures.
- CT provides clearer, more detailed pictures than traditional X-rays.
- A cardiac CT is a special type of CT scan designed to detect the buildup of plaque in the coronary arteries.
- Exams take up to 90 minutes; the actual scanning takes about 10 minutes.
- You will be asked not to drink anything with caffeine on the day of the exam, and not to eat in the two hours before the exam.
- You will receive an injection of contrast—a substance that makes the image more clear—just before scanning.
- If you are over 60 or have kidney disease, diabetes, lupus, or multiple myeloma, you’ll need a blood test beforehand to make sure the contrast will be safe for you.
- To help us get clear images, you may also receive a medicine called a beta blocker that reduces your heart rate for a short time.
- We will attach electrodes to your chest to monitor your heart rate during the exam.
- The trained professional performing your exam, called a technologist, will be nearby and able to talk to you throughout the scan.
- You will be asked to hold your breath for 12 to 18 seconds a few times during the scan.
- CT exams require that you lie still in a confined space. But because the scanning time is so short, most people tolerate the experience well.
- Every exam is interpreted by a cardiac-imaging specialist. A specialist is capable of seeing and understanding subtle things due to advanced training and singular focus.
- We use the latest technology, and the capabilities of our state-of-the-art scanners play a key role in tailoring each exam to your specific needs and reducing radiation exposure.
Cardiac CT in depth
What is cardiac CT?
A CT (computed tomography) scan is a noninvasive medical test that uses special X-ray equipment to produce multiple images or pictures of the inside of the body and a computer to join them together in cross-sectional views of the area being studied.
A Cardiac CT scan is a non-invasive way of obtaining information about the location and extent of calcified plaque in the coronary arteries--the vessels that supply blood to the heart wall. Plaque is a build-up of fat and other substances, including calcium, which can, over time, narrow the arteries or even close off blood flow to the heart. The result may be painful angina in the chest or a heart attack. Because calcium is a marker of coronary artery disease, the amount of calcium detected on a Cardiac CT scan is a helpful diagnostic tool.
CT examinations improve health care and are an essential part of diagnosis and treatment planning. However, there are some risks associated with the level of radiation exposure during a CT and therefore the medical benefit of conducting the exam should always outweigh any risks involved. No direct data have shown that CT examinations are associated with an increased risk of cancer; extrapolations from studies of radiation exposure suggest there is a very small incremental risk.
At Mass General Imaging, we pay special attention to minimizing radiation exposure—without giving up image quality. Dose reduction has long been a priority for our entire staff, including radiologists, the technologists who administer most exams, researchers, and equipment engineers. We use many strategies to reduce exposure, from taking advantage of the latest technology to customizing exams for each patient.
Our radiologists are part of the Massachusetts General Heart Center—a multidisciplinary program that unites expert medical professionals from Imaging, Cardiology, Cardiac Surgery, Cardiac Anesthesia, and Cardiac Nursing to provide patients with the very best in cardiac care.
What should I expect BEFORE my cardiac CT?
- Food and drink: On the day of the exam, please do not consume any caffeinated beverages or food (coffee, caffeinated sodas, chocolate etc). Do not eat food within the last 2 hours prior to the exam. You may drink clear non-caffeinated liquids until you arrive at the scanner.
- Medications: You may take any medication that you usually take, except for metformin (Glucophage). You must discontinue the use of metformin at the time of or prior to the procedure, and withhold the use of metformin for 48 hours after the procedure, starting it again only after your doctor as evaluated your renal function and found it to be normal.
- When to arrive: We ask you to arrive 30 minutes prior to your appointment time. We will ask you a series of questions that will determine whether or not it is safe for you to undergo the CT. Your early arrival will help to ensure that we are able to perform the test efficiently and safely.
- Preparation: An intravenous catheter will be inserted in your arm for intravenous contrast injection. If you have a known contrast allergy or had a reaction to contrast dye, please tell your physician and CT technologist prior to the exam. Electrocardiogram leads will be placed on your chest in order to monitor your heartbeat. Before beginning the Cardiac CT exam, you will be coached in a method to hold your breath. You will be asked to hold your breath a few times for 12-18 seconds.
- Beta blocker: The image quality of Cardiac CT examinations is highly dependant on your heart rate during the scan. The desired heart rate is ~60bpm. Therefore the cardiac imaging physician may administer an intravenous beta-blocker immediately prior to the examination.
Please inform the cardiac imager of any known contraindications to the use of beta-blockers when ordering the exam. In patients with known high heart rates, the administration of oral beta-blocker the evening prior to and the morning of the exam may be very helpful. Referring physicians may consider prescribing an oral beta-blocker if a patient has a high heart rate.
What should I expect DURING my cardiac CT?
- Scanning: Your CT technologist will bring you into the CT scan room where you will lie down on the patient table. The technologist positions your body in the middle of the large doughnut-shaped scanner ring which holds the X-ray tube and an electronic detector. The technologist leaves the room, but is in full view and communication with you through the observation window in the adjoining room.
The scanner does not touch you, nor do you feel the x-rays. It does make some noise and the table you are lying on may move slightly to make adjustments for a better view. It is important for you to lie very still and at some points, you may be asked to briefly hold your breath as the picture is taken. During the scan, a thin beam of X-ray is focused on a specific part of your body. The X-ray tube moves very rapidly around this area, enabling multiple images to be made from different angles to create a cross-sectional picture. The X-ray beam information goes to the electronic detector and then into a computer, which analyzes the information and constructs an image for the radiologist to interpret.
What should I expect AFTER my cardiac CT?
- Instructions: You will have no restrictions after the exam and can return to normal activities.
- Exam results: Typically, the results of any examination will be available to your doctor within 24 hours. Your doctor will communicate the results of your study directly to you.
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