膝关节MRI扫描

定义

A knee MRI (magnetic resonance imaging) scan uses energy from strong magnets to create pictures of the knee joint and muscles and tissues.

核磁共振成像不使用辐射(x射线). 单个MRI图像称为切片. The images can be stored on a computer or printed on film. 一次检查产生许多图像.

选择的名字

MRI - knee; Magnetic resonance imaging - knee

如何执行测试

You will wear a hospital gown or clothes without metal zippers or snaps (such as sweatpants and a t-shirt). Please remove your watches, glasses, jewelry, and wallet. 核磁共振成像可以拉出任何金属物体. Certain types of metal can cause blurry images.

You will lie on a narrow table that slides into a large tunnel-like scanner.

一些检查使用一种特殊的染料(造影剂). Most of the time, you will get the dye through a vein (IV) in your arm or hand before the test. 有时，染料被注入关节. The dye helps the radiologist see certain areas more clearly.

During the MRI, the person who operates the machine will watch you from another room. The test most often lasts 30 to 60 minutes, but may take longer. 可能会很吵. The technician can give you some ear plugs if needed.

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 closed spaces (have claustrophobia). You may be given a medicine to help you feel sleepy and less anxious. Your provider may suggest an "open" MRI, in which the machine is not as close to the body.

Before the test, tell your provider if you have:

• 脑动脉瘤夹
• 某些类型的人工心脏瓣膜
• 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)
• Recently placed artificial joints or surgical repairs using metal plates and screws
• 某些类型的血管 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 MRI scanner:

• Pens, pocketknives, and eyeglasses may fly across the room.
• Items such as jewelry, watches, credit cards, and hearing aids can be damaged.
• 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. 你需要安静地躺着. Too much movement can blur MRI images and cause errors.

The table may be hard or cold, but you can ask for a blanket or pillow. The machine makes loud thumping and humming noises when turned on. You can wear ear plugs to help block out the noise.

An intercom in the room allows you to speak to someone at any time. Some MRIs have televisions and special headphones to help the time pass.

There is no recovery time, unless you were given a medicine to relax. After an MRI scan, you can return to your normal diet, activity, and medicines.

为什么要进行测试

Your provider may order this test if you have:

• An abnormal result on a knee x-ray or bone scan
• A feeling that your knee is giving away in the knee joint
• 膝关节后关节积液(贝克囊肿)
• 膝关节积液
• 膝关节感染
• 膝盖骨损伤
• 膝盖疼痛伴发烧
• 走路或移动时膝盖被锁住
• Signs of damage to the knee muscle, cartilage, or ligaments
• 膝盖疼痛 这种情况不会随着治疗而好转
• 膝关节不稳定

You may also have this test to check your progress after knee surgery.

正常的结果

正常的结果意味着你的膝盖看起来没问题.

异常结果意味着什么

Abnormal results may be due to a sprain or tear of the ligaments in the knee area.

异常结果也可能是由于:

• 衰老随着年龄的增长而发生的退化或变化
• 半月板或软骨损伤
• 膝关节关节炎
• 股骨头坏死 (也叫骨坏死)
• 骨肿瘤或癌症
• 骨折
• 膝关节后关节积液(贝克囊肿)
• 骨感染(骨髓炎)
• 炎症
• 膝盖骨受伤

Talk to your provider if you have questions or concerns.

风险

核磁共振成像不使用辐射. There have been no reported side effects from the magnetic fields and radio waves.

The most common type of contrast (dye) used is gadolinium. 它很安全. Allergic reactions to the substance are rare. However, gadolinium can be harmful to people with kidney problems that need dialysis. If you have kidney problems, please tell your provider before the test.

The strong magnetic fields created during an MRI can cause heart pacemakers and other implants to not work as well. It can also cause small pieces of metal inside your body to move or shift. For safety reasons, please do not bring anything that contains metal into the scanner room.

注意事项

Tests that may be done instead of a knee MRI include:

• 膝关节的CT扫描
• 膝盖x射线

参考文献

赫尔姆斯CA. 膝关节的磁共振成像. 见:赫尔姆斯CA编辑. 基础 骨骼放射学. 5日艾德. Philadelphia, PA: Elsevier; 2020:chap 9.

Kapoor G, tom AP. Current status of imaging of the musculoskeletal system. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. 格兰杰 & 埃里森的 诊断放射学. 7日艾德. Philadelphia, PA: Elsevier; 2021:chap 38.

Riff AJ, Chalmers PN, Bach BR. 膝关节诊断和决策. 见:米勒博士，汤普森博士，编辑. 口腔、Drez & 米勒的骨科运动医学. 5日艾德. Philadelphia, PA: Elsevier; 2020:chap 90.