正电子发射断层扫描(PET)

什么是心脏PET扫描?

心脏PET扫描是一种无创核成像检查. It uses radioactive tracers (called radionuclides) to produce pictures of your heart. 医疗保健专业人员使用心脏PET扫描来诊断 冠状动脉疾病(CAD) 以及a造成的损害 heart attack. PET扫描可以显示健康和受损的心肌. PET scans are also used to help find out if you will benefit from a 经皮冠状动脉介入治疗 比如血管成形术和支架植入， 冠状动脉搭桥手术 (CABG)或其他手术. 

我为什么需要它?

A PET scan can accurately diagnose coronary artery disease and detect areas of low blood flow in the heart. PET can also identify dead tissue and injured tissue that’s still living and functioning. If the tissue is viable, you may benefit from a PCI or 冠状动脉搭桥手术.

PET扫描是如何工作的?

一种放射性示踪剂被注射到你的血液中. The tracers used for PET are mostly natural body compounds such as glucose, 水或氨, which are labeled or “tagged” with a small amount of radioactive material. Inside your body the radioactive tracer produces a type of energy called a gamma ray. Gamma rays are detected by a gamma detector and are used to produce a series of clear images of your heart. Images of thin slices made all the way through the heart can be produced from all different directions and angles.

Computer graphics can be used to create a three-dimensional image of your heart from the thin-slice images.

Your health care professional will be able to tell whether your heart muscle is functioning by how well it takes up and uses the different tracers. Your health care professional will examine the images to find where the tracer is. Viable heart tissue will take in more of the tracer than tissue that’s no longer viable.

心脏PET的风险是什么?

心脏PET对大多数人来说是安全的. The amount of radiation is small, and your body will get rid of it through your kidneys or stool. 多喝水，把它排出体外. 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.

我该如何准备扫描?

• 告诉你的医疗团队你服用的任何药物, 包括非处方药, 草药和维生素. 你可能会被要求在考试前不要参加一些考试.
• 如果你有糖尿病并服用胰岛素, ask how much insulin you should take before the scan and what you should eat. 你的血糖水平将在测试过程中被监测. 糖尿病患者的检测结果并不总是准确的.
• 你也可能被要求避免某些食物和饮料, 比如含咖啡因的饮料或酒精, 检查前24小时.
• Don’t eat, and drink only water for 4 to 6 hours before your test.
• Wear comfortable, loose-fitting clothing, and don’t wear jewelry or other metal objects.
• Tell your health care team if you’re afraid of tight spaces or have anxiety from being enclosed.

扫描过程中发生了什么?

A health care professional and a nuclear medicine technologist usually perform the scan in a hospital or at a PET center using special equipment.

• The technologist will place small metal disks (electrodes) on your chest, arms and legs. 磁盘上的电线连着一台记录你的 心电图 (ECG or EKG). The ECG keeps track of your heartbeat during the test and can signal the computer when to take a scan.
• 你的手臂上将有静脉注射管. 示踪剂将通过静脉注射.
• You’ll lie on a flat table that’s connected to the PET scanner and a computer. The table will slide into the scanner, which is shaped like a giant doughnut.
• Within the PET scanner, detectors record the radioactive patterns of the tracer in your heart. The information is transformed into images on a computer screen. Several scans are done over time to provide pictures of thin slices of your entire heart from all angles. It’s very important to hold completely still with your arms above your head while each scan is being done.
• Your health care team will take a baseline picture of your heart before the tracer is injected. 这大约需要15到30分钟. 
• Next, the tracer will be injected and your heart will be scanned again.
• If you have a nuclear chemical stress test (also called a pharmacologic stress test), you’ll get a medicine that increases the blood flow in your heart, 类似于运动时发生的情况. These medicines may include adenosine, dipyridamole (Persantine) or dobutamine. The health care team will examine how well your heart takes up the tracer before and after receiving the medicine. 如果你有严重的冠状动脉疾病, some areas of your heart may not get enough blood during stress so the tracer won’t show up in those areas.
• 测试需要1到3个小时.

我的PET扫描后会发生什么?

• Ask your health care professional if you can go back to your normal activities right away.
• Drink plenty of water for the next 24 hours to flush the radioactive material from your body.
• Make an appointment with your health care professional to discuss the results of the test and next steps.