Nuclear Cardiac Imaging
A cardiac nuclear medicine exam is used to study the structure and function of the heart. Blood vessels of the heart are best studied by watching the change in blood flow due to exercise. Therefore you will undergo a stress test – either through physical exercise or by a drug that simulates exercise – to make your heart work harder than normal. You will then be given a radioactive compound, called a tracer. The tracer will collect in your heart muscle and will emit gamma rays, which the gamma camera detects. A computer will then produce pictures of the heart by means of the detected gamma rays.
What to Expect
The combination stress/rest exam may be performed in one day or on two separate days. For the resting portion, a small amount of tracer will be injected into a vein in your arm. After a 45-minute wait, imaging of your heart will be performed with a gamma camera while you are lying on your back with your arms above your head.
For the stress portion of the exam, electrodes will be attached to your chest to monitor your heart activity during the stress test. You will walk on a treadmill for a few minutes or, if you are unable to exercise, you will be given a drug that will simulate exercise. A physician will monitor your ECG and your blood pressure.
A second dose of the tracer is given when the blood flow to the heart is at peak stress level. The tracer will collect in your heart within the following 45 minutes. The gamma camera will then be used to obtain more pictures. You will need to lie very still during that part of the exam, which takes about 20 minutes. A comparison of the images is done to conclude whether or not blood flow to your heart has changed between the resting and stress states, and to check for heart disease.
The entire exam will take approximately three hours if done in one day. Often, the study is scheduled as a two-day exam.