心肌灌注显像试验

什么是心肌灌注显像检查?

Myocardial perfusion imaging (MPI) is a non-invasive imaging test that shows how well blood flows through your heart muscle. It can show areas of the heart muscle that aren’t getting enough blood flow. 它还可以显示心脏肌肉的泵送情况. 这种测试通常被称为核压力测试.

MPI有两种类型: 单光子发射计算机断层扫描 and 正电子发射断层扫描.

MPI is useful in people with chest discomfort to see if the pain comes from lack of blood flow to the heart muscle caused by narrowed or blocked heart (coronary) arteries. 这种疼痛被称为 angina. MPI doesn’t show the heart arteries themselves but can tell your health care professional if and how many  arteries are blocked. 该测试还可以显示你以前是否有过 heart attack.

If you have chest pain and an abnormal MPI test, the next step may be performing a 冠状动脉造影(PDF). 如果MPI测试正常, your health care professional will look into other causes of your chest pain.

为什么人们要做MPI测试?

MPI tests can help your health care professional find out if you:

• 心脏动脉变窄或堵塞.
• 心脏病发作导致心脏受损.
• 应该做冠状动脉造影吗. 
• Would benefit from a coronary stent or bypass surgery to treat your chest discomfort or help your heart pump normally.

MPI测试还可以显示:

• If a heart procedure you had to improve blood flow (stent, bypass) is working.
• 你的心脏对体力活动的承受能力如何.

如果测试正常, it means that no blood flow problems were found and your heart is functioning properly. 异常结果可能意味着存在心脏病. Discuss the findings with your health care professional and whether more testing will be needed and how severe the condition is.

MPI测试的风险是什么?

MPI测试对大多数人来说通常是安全的. MPI研究将你暴露在低剂量的辐射中. Experts disagree if radiation at such low doses can cause cancer, 但也有可能没有剂量的辐射, however low, 是完全安全的.  Discuss whether or not to undergo the test with your health care professional based on your risk of heart disease. 如果你怀孕了或者觉得自己可能怀孕了, 或者如果你是一个哺乳的母亲, 在你做这个测试之前告诉你的医疗保健专业人员. 它可能会伤害你的孩子.

我如何准备我的MPI考试?

• Tell your health care professional about any medicines you take, 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.
• Don’t eat certain foods, such as caffeine-containing beverages (i.e., coffee, tea and soft drinks) or chocolate for 24 hours before your test if your told not to. The test may have to be postponed or cancelled if you drink caffeine.
• You may be instructed to avoid eating and drinking after midnight before your test.
• Wear comfortable, loose-fitting clothing and comfortable shoes.

在我的MPI测试中发生了什么?

Specially trained technicians usually perform the test in a hospital or clinic with special equipment.

• The technician places small pads (electrodes) on your chest, arms and legs. The pads have wires that hook up to a machine to record your electrocardiogram (ECG or EKG). The ECG keeps track of your heartbeat during your test and is used to tell the camera when to take a picture.
• You’ll wear a cuff around your arm to track of your blood pressure.
• 技术人员会在你的手臂上插入静脉注射管. 
• 你可以在跑步机上或固定自行车上锻炼.
• 如果你不能锻炼, your IV will be connected to a bag that has a medicine to widen the arteries in your heart or make it go faster, 就像你锻炼的时候一样. 这被称为化学压力测试.
• 当你达到你的最高活动水平时, you’ll stop and receive a small amount of radioactive material (tracer) through the IV.
• You’ll lie still on a table for 10-30 minutes while the gamma camera takes pictures of your heart. Several scans are done during that time to provide pictures of thin slices of your entire heart from all angles. It’s important to hold still with your arms above your head while the pictures are being taken.
• 在测试的休息部分, you’ll receive more tracer and another set of pictures will be taken. This set of images will be compared to the images taken after exercise or stress.
• Some forms of the test don’t use stress or exercise but take sets of resting images with a tracer. 

测试需要三到四个小时. Some labs may do the resting part of the test first or do the resting and exercise tests on different days.

我的MPI测试后会发生什么?

• You can usually go back to your normal activities as directed by your heath care professional.
• Drink plenty of water to flush the radioactive material from your body.
• Make an appointment with your health care professional to discuss the test results and next steps.
• Ask for a note confirming your recent MPI test if you plan on travelling within a few days after your test. The radioactive material still in your body may trigger alarms in the airport.