核磁共振成像

定义

A magnetic resonance imaging (核磁共振成像) scan is an imaging test that uses powerful magnets and radio waves to create pictures of the body. 它不使用电离辐射(x射线).

单个核磁共振成像图像称为切片. The images can be stored on a computer or printed on film. 一次检查可以产生数千张图像.

不同类型的核磁共振成像包括:

• 腹部核磁共振
• 颈椎核磁共振
• 胸部核磁共振
• 头颅核磁共振
• 心脏核磁共振
• 腰椎核磁共振成像
• 盆腔核磁共振成像
• MRA(磁共振血管造影)
• MRV(磁共振静脉造影)

选择的名字

Magnetic resonance imaging; Nuclear magnetic resonance (NMR) imaging

如何执行测试

You may be asked to wear a hospital gown or clothing without zippers or snaps (such as sweatpants and a t-shirt). 某些类型的金属会导致图像模糊.

You will lie on a narrow table, which slides into a large tunnel-shaped scanner.

有些检查需要特殊的染料(造影剂)。. Most of the time, the dye will be given through a vein (IV) in your hand or fore手臂 before the test. The dye helps the radiologist see certain areas more clearly.

小型设备, 称为线圈, 可以放在头部周围吗, 手臂, 或腿, 或者在其他有待研究的领域. These help send and receive the radio waves, and improve the quality of the images.

During the 核磁共振成像, the person who operates the machine will watch you from another room. The test usually lasts about 30 to 60 minutes, but may take longer.

如何准备考试

You may be asked not to eat or drink anything for 4 to 6 hours before the scan.

Tell your health care provider if you are afraid of close spaces (have claustrophobia). You may be given a medicine to help you feel sleepy and less anxious, 或者你的十大赌博平台排行榜可能会建议你做开放式核磁共振, 在这种情况下，机器离身体不那么近.

在测试前，告诉你的十大赌博平台排行榜你是否有:

• 人工心脏瓣膜
• 脑动脉瘤夹
• 心脏除颤器或起搏器
• 内耳(耳蜗)植入物
• Kidney disease or dialysis (you may not be able to receive contrast)
• 最近放置的人工关节
• 血管 支架
• Worked with sheet metal in the past (you may need tests to check for metal pieces in your eyes)

因为核磁共振成像含有强磁铁, metal objects are not allowed into the room with the 核磁共振成像 scanner:

• Items such as jewelry, watches, credit cards, and hearing aids can be damaged.
• Pens, pocketknives, and eyeglasses may fly across the room.
• Pins, hairpins, metal zippers, and similar metallic items can distort the images.
• Removable dental work should be taken out just before the scan.

考试的感觉如何

核磁共振检查不会引起疼痛. If you have difficulty lying still or are very nervous, you may be given a medicine to relax you. Too much movement can blur 核磁共振成像 images and cause errors.

The table may be hard or cold, but you can request a blanket or pillow. The machine produces loud thumping and humming noises when turned on. 你可以戴上耳塞来减少噪音.

An intercom in the room allows you to speak to someone at any time. Some 核磁共振成像 facilities have televisions and special headphones that you can use to help the time pass.

There is no recovery time, unless you were given a medicine to relax. After an 核磁共振成像 scan, you can resume your normal diet, activity, and medicines.

为什么要进行测试

核磁共振成像通常会有所帮助:

• 诊断感染
• 在活检时，引导十大赌博平台排行榜到正确的区域
• 鉴别肿块和肿瘤，包括癌症
• 研究血管

核磁共振成像 images taken after a special dye (contrast) is delivered into your body may provide extra information about the blood vessels.

A 磁共振血管造影(MRA) is a form of magnetic resonance imaging that creates 3-dimensional pictures of blood vessels.

正常的结果

A normal result means the body area being studied looks normal.

异常结果意味着什么

Results depend on the part of the body being examined and the nature of the problem. Different types of tissues send back different 核磁共振成像 signals. For example, healthy tissue sends back a slightly different signal than cancerous tissue. Consult your provider with any questions and concerns.

风险

核磁共振不使用电离辐射. No side effects from the magnetic fields and radio waves have been reported.

The most common type of contrast (dye) used is gadolinium. This substance is thought to be generally safe for most people. Gadolinium is retained in the brain and other organs (including the skin in people with kidney disease) after use. In rare cases, organ and skin damage have occurred in patients with preexisting kidney failure. Tell your provider before the test if you have kidney problems.

The strong magnetic fields created during an 核磁共振成像 can cause heart pacemakers and other implants not to work as well. The magnets can also cause a piece of metal inside your body to move or shift.

参考文献

Carpenter JP, Litt H, Gowda M. 磁共振成像和动脉造影. 见:Sidawy AN, Perler BA编. Rutherford's 血管 Surgery and Endovascular Therapy. 10日艾德. Philadelphia, PA: Elsevier; 2023:chap 30.

莱文MS，戈尔RM. 胃肠病学诊断成像程序. 参见:Goldman L, Schafer AI主编. Goldman-Cecil医学. 26日艾德. Philadelphia, PA: Elsevier; 2020:chap 124.

Van Thielen T, van den Hauwe L, Van Goethem JW, Parizel PM. Current status of imaging of the spine and anatomical features. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. 格兰杰 & Allison's Diagnostic Radiology: A Textbook of Medical 成像. 7日艾德. Philadelphia, PA: Elsevier; 2021:chap 47.

Wymer DTG, Wymer DC. 成像. In: Feehally J, Floege J, Tonelli M, Johnson RJ, eds. 综合临床肾脏病学. 6日艾德. Philadelphia, PA: Elsevier; 2019:chap 5.