Both cardiac MRI and cardiac CT scan are used to take images of the heart:
- Cardiac MRI. This uses strong magnets and radio waves. A cardiac MRI scan can show problems with heart structure, abnormal blood flow, or tissue damage.
- Cardiac CT scan. This uses X-rays and computer processing technology. A cardiac CT scan can show problems with heart structure, especially if there is damage to blood vessels.
The scans are done by a technologist or radiologist. A radiologist is a doctor trained to diagnose and treat problems with imaging technology. The scans can also be done by a cardiologist with special training in radiology. A cardiologist is a doctor trained to diagnose and treat heart problems. The scan can take place in either a hospital or outpatient imaging center. A cardiac MRI scan lasts about 60 to 90 minutes and cardiac CT scan lasts about 30 minutes.
You may need to do the following before your cardiac MRI or CT scan:
- Follow any directions given for taking medicines and for not eating or drinking before the test.
- Follow your normal daily routine unless the healthcare provider tells you otherwise.
- Remove any makeup. Makeup may contain some metal.
- Remove ear (cochlear) implants.
- Make a list of all implanted devices and any metal in your body. These include shrapnel or bullet fragments. Discuss these with your healthcare provider and the MRI technologist. If there is any uncertainty, an X-ray may be taken of the involved body part to be sure.
- Remove any metal objects, including watches, eyeglasses, hearing aids, jewelry, belts, or clothing with zippers. These things may interfere with the MRI scanner’s magnetic field. Dental braces and fillings aren’t a problem. But in many cases, MRI scans shouldn’t be done if you have metal implants.
What to expect during the scan:
- Movement affects the quality of the results and can even need a repeat scan. Restraints may be used or you may be given a sedative (medicine that makes you relax or sleep).
- Contrast dye may be used to improve image results.
- A coil may be placed over the heart during a cardiac MRI scan. The coil sends and receives radio waves and helps improve image results.
- Small, EKG stick-on type patch leads may be attached to the chest.
- If awake, you may speak to and hear the technologist through a speaker inside the scanner.
- During a cardiac MRI scan, you will get earplugs to block out the noise from the scanner.
- During a cardiac CT scan, you may be asked to hold your breath at certain points to improve image results.
What to expect after the scan:
- If a sedative or anesthesia was given, you may be taken to a recovery room. It may take 1 to 2 hours for any medicines to wear off.
- Unless told not to, you can return to a normal routine and diet right away.
- Any contrast dye given should pass through the body in about 24 hours. The healthcare provider may tell you to drink extra water or other fluids during this time.
- The images are reviewed by a radiologist and cardiologist. The cardiologist will follow up with you with complete results.
While uncommon, risks and possible complications include:
- Allergic reaction to contrast dye, such as hives, itching, or wheezing
- Kidney damage from IV contrast dye used in CT scan (rarely)
- Nephrogenic systemic fibrosis, an illness that has been linked to MRI IV contrast material (extremely rare)
- Problems with undetected metal implants or foreign bodies (only with MRI)
- Radiation exposure from X-rays (only with CT scan)
- Reaction to sedative or anesthesia, such as headaches, shivering, and vomiting