单光子发射计算机断层扫描(SPECT)

什么是心脏SPECT扫描?

A SPECT scan of the heart is a noninvasive nuclear imaging test. It uses radioactive tracers that are injected into the blood to produce pictures of your heart. 医生使用SPECT进行诊断 冠状动脉疾病 然后求出a 心脏病 发生. SPECT (called a myocardial perfusion scan) can show how well blood is flowing to the heart and how well the heart is working. 

为什么人们要做心脏SPECT扫描?

SPECT scans show areas of your heart that have low blood flow at rest or during exercise. This information helps your health care professional find out:

• 如果你有冠状动脉疾病.
• 如果你有心脏病发作后留下的疤痕组织.
• 旁路手术或其他心脏手术效果如何.
• If you are having a 心脏病 and need more immediate tests such as a cardiac catheterization or percutaneous coronary intervention.
• 如果你有心脏病发作的危险.

SPECT扫描是如何工作的?

A small amount of radioactive tracer is injected into your bloodstream. Inside your body, the tracer produces a type of energy called gamma rays. 伽马摄像机接收到追踪器发出的信号, and a computer converts them into pictures of blood flow through your heart. Images of thin slices made all the way through the heart can be produced from all different directions and angles. These images are reviewed for the location and distribution of the tracer. Computer graphics can be used to create a 3-dimensional image of your heart from the thin-slice images.

SPECT scans can be done while you rest and during an exercise 压力测试 (称为核压力测试). The 压力测试 gives your health care professional a better idea of how well your heart handles work. 如果你不能锻炼, you may get a medicine to increase the blood flow in your heart as if you were exercising. 这被称为化学或药理学压力测试.

• 如果在运动和休息期间测试正常, 冠状动脉的血流正常.
• The test may show normal blood flow at rest but not after exercise. This may be due to a blockage in one or more coronary (heart) arteries. A blockage can create an area where little to no uptake of tracer can be seen.
• 运动和休息时测试结果都可能不正常. 在这种情况下，示踪剂在某个区域将不可见. This means that not enough blood is flowing to that area of the heart at any time. 
• Lack of tracer may mean the cells in that area are dead from a prior 心脏病. (它们变成了疤痕组织.)可能需要其他影像学检查来评估这一点.
• By using specific radioactive tracers designed for this test, SPECT scans can also show how well your heart’s left ventricle (lower pumping chamber) is working.

心脏SPECT扫描的风险是什么?

心脏SPECT扫描对大多数人来说是安全的. 辐射量很小, and your body will get rid of it through your kidneys in about 24 to 72 hours.

If you’re pregnant or think you might be pregnant, tell your health care professional. They may have you wait until after your pregnancy to have the scan if it's not urgent. 如果你是哺乳期的母亲, you should pump enough milk for a couple of days of feedings before your scan or feed your baby formula for one to two days after the scan.

我该如何准备心脏SPECT扫描?

• 告诉你的医生你服用的任何药物, 包括非处方药, 草药和维生素. 他们可能会要求你在考试前不要服用.
• You may be asked not to have caffeine-containing food or drinks for 24 hours before your test. 咖啡因会影响测试结果. 
• Don’t eat, and drink only water for 4 to 6 hours before your test.
• Wear loose-fitting clothing and comfortable shoes if you will have an exercise 压力测试.

在心脏SPECT扫描期间发生了什么?

A doctor and nuclear medicine technologist usually perform the scan in a hospital or clinic using special equipment.

• The technician will place small disks or pads (electrodes) on your chest, arms and legs. The electrodes have wires that hook to a machine that records your electrocardiogram (ECG or EKG). The ECG keeps track of your heartbeat during the test and can be used to signal the camera when to take a picture.
• You’ll wear a cuff around your arm to track your blood pressure.
• The technician will put an intravenous line (IV) in your arm. 示踪剂将通过静脉注射. 
• 静息扫描, you’ll lie on a table and a gamma camera will move around your chest and convert the tracer’s signals into pictures. 
• For a nuclear 压力测试, you’ll either walk on a treadmill or ride on a stationary bicycle. 然后你再躺在桌子上拍更多的照片. 如果你不能锻炼, you’ll receive a medicine through the IV to increase the blood flow in your heart similar to what occurs during physical activity. 测试可能需要大约一个小时.

我的SPECT扫描后发生了什么?

• You can usually go back to your normal activities right away.
• 在接下来的几天里多喝水. This will help flush the radioactive material from your body.
• Make an appointment with your health care professional to discuss the test results and next steps.