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吕玉波
吕玉波 副主任医师
好大夫工作室 医学影像科

磁共振成像(MRI)检查、检查前准备及注意事项

一、什么是MRI检查?What is MRI?

MRI即磁共振成像,是利用磁场及其梯度、射频脉冲,通过计算、记录人体内不同组织氢质子(如:水)含量与分布,以图像的形式显示人体各组织器官的解剖结构及其病变的病理生理进程。MRI对人体无电离辐射损害。

Magnetic resonance imaging(MRI),is use of the magnetic field and its gradient,radio frequency pulse to computer test and record 1H(such as:water)in human body.In the form of image to display tissues or organs anatomic structure and disease pathophysiological process.MRI has no ionizing radiation.

二、磁共振检查都有哪些用途?The clinic application of MRI?

磁共振可以用来进行身体各部位的检查,譬如:头颅,脊柱,四肢(肩关节、膝关节,肘关节、腕关节踝关节等),腹部,盆腔,乳腺,心脏和其他部位。由于磁共振使用多参数,多对比度成像,在一些部位的检查上要优于其他检查项目。

MRI can be used for scanning:head,spine,limbs(shoulder,knee,elbow and wrist joints of ankle,etc.),abdominal,pelvic,breast,heart and other parts.MRI’s multiparameter,multi-contrast imaging is better than CT or X-ray.

1.颅脑神经Neuroimaging

MRI比CT具有更好的组织分辨率,能更清楚地显示大脑功能性及结构性异常,包括肿瘤、脑血管疾病、中风、脱髓鞘疾病、痴呆、脑炎及癫痫等。磁共振血管造影(MRA)可直观地评价脑动脉狭窄程度及有无动脉瘤。

MRI has better resolution than CT and offers better visualization for study both functional and structural brain abnormalities,including tumors,cerebrovascular disease,stroke,demyelinating diseases,dementia,infectious diseases and epilepsy.Magnetic resonance angiography(MRA)generates pictures of the arteries to evaluate them for stenosis(abnormal narrowing)or aneurysms(vessel wall dilatations,at risk of rupture).

2.骨关节肌肉系统Musculoskeletal

包括脊柱成像,评估骨转移瘤、关节损伤及软组织肿瘤性病变等。

例如,如果您有背部疼痛,它可能是因为椎间盘突出导致。常规的X线只能显示脊椎骨却无法显示椎间盘;MRI扫描可以清晰地显示椎间盘,因此会提示椎间盘是否突出和压迫神经。有助于外科医生决定是否需要开展手术。

MRI扫描可以检测到关节周围韧带撕裂的情况,因此越来越多地被用于检查运动性损伤。

Applications in the musculoskeletal system includes spinal imaging,assessment of metastatic bone tumor,joint disease and soft tissue tumors.

For example,if you have back pain it may be caused by a disc which is protruding(a'slipped disc').A normal x-ray cannot show the disc,only the spinal bones,and so is not very useful.An MRI scan can show the discs clearly,and will show if one is protruding and pressing on a nerve.This helps a surgeon to decide if an operation is needed.

Even torn ligaments around joints can be detected by an MRI scan.So,it is being used more and more following sports injuries.

3.腹部及盆腔Abdomen and Pelvis

MRI腹部成像用来检测和描述肝脏、胆囊胆管、胰腺、脾脏、肾脏等器官病变,往往需要静脉注射对比剂。磁共振胰胆管造影(MRCP)不需注射造影剂即可清晰进行胆管(道)的解剖成像。

Abdomen MRI is used to detect and characterize focal or diffuse lesions of liver,gallbladder bile duct,pancreas,spleen,kidney,rectal,prostate and other organs.Dynamic contrast enhancement sequences are normally needed.Anatomical imaging of the bile ducts is achieved by using a heavily T2-weighted sequence in magnetic resonance cholangiopancreatography(MRCP)without contrast injection.

4.肿瘤Oncology

MRI可用于癌症的筛查、术前分期及分级、术后及化疗后评估疗效等.

MRI has a role in the cancer diagnosis,preoperative staging and follow-up.

三、MRI检查的注意事项有哪些?The attention tips of MRI?

1.磁共振设备,具有强大磁场,严禁病人和家属将所有铁磁性的物品及电子产品靠近或带入检查室,这些物品包括:所有通讯物品;各种磁卡;掌上电脑、计算器、强心卡等电子用品;钥匙、打火机、金属硬币、刀具、钢笔、针、钉、镙丝等铁磁性制品;发夹、眼镜、假眼、活动假牙、金属饰品、手表等不明材质的物品;易燃易爆品、腐蚀性药品、药膏、膏药等;病床、轮椅等。

2.体内安装、携带以下装置或物品的患者及家属不能进入磁体间,否则有生命危险及其它危险性伤害。包括:心脏起搏器、人工心脏瓣膜、动脉瘤术后金属夹、植入体内的药物灌注装置、植入体内的任何电子装置(神经刺激器、骨骼生长刺激器)、血管内栓塞钢圈、滤器、心电记录监护器、金属缝合线、体内有弹片或铁砂粒者、助听器、人工耳蜗、中耳移植物、眼内金属异物等。

3.神志不清的危重患者禁止磁共振检查。有各种手术史患者及家属需于检查前特别声明,以策安全。

1.MRI,with strong magnetic field,prohibits the patients and family members from bringing all ferromagnetic and electronic to the scanning room,which include all communication items;Various magnetic CARDS;Palmtop computer,calculator,strong heart card and other electronic products;Key,cigarette lighter,metal coin,cutter,pen,pin,nail,screw and other ferromagnetic products;Hair clips,eyeglasses,false eyes,movable denture,metal ornaments,watches,etc.Inflammable and explosive products,corrosive drugs,ointments,plaster,etc.Hospital bed,wheelchair etc.

2.The patient and family members who have the following devices or articles are not allowed to enter the MRI scanning area,otherwise there will be danger of life and other dangers.Include:heart pacemakers,artificial heart valve,aneurysm surgery metal clips,drug infusion device implanted in the bodies,any electronic devices implanted in bodies(nerve stimulator,bone growth stimulator),endovascular embolization rims,filter,ECG record monitor,metal suture,with shrapnel or iron ore pellets in vivo,hearing AIDS and cochlear implants,middle ear implant,intraocular foreign body,such as metal.

3.Patients with unconsciousness in critically ill patients are prohibited from MRI.Patients with various surgical histories and family members need to make a special statement before the examination to ensure safety.

四、孕妇和小孩做磁共振到底有没有影响?MRI scanning of pregnant women and children?

众所周知,CT、X线平片、透视都存在电离辐射。不提倡孕妇使用。磁共振一般认为是安全的。但是孕期前三个月行磁共振(MRI)对胎儿的安全性问题无法给出确切的答案。因为磁共振的发展时间还是太短。但是孕期行钆对比剂增强扫描需要引起注意,其与风湿免疫疾病、炎症、浸润性皮肤疾病、死产或新生儿死亡的风险增加相关。当然该研究也存在一定的局限性,其无法检测罕见的不良结局。临床工作中一般建议孕前三个月避免做MRI检查,孕期禁止做MRI增强检查。不建议对一周岁以下的小孩进行增强检查。

It is well known that there are ionizing radiation in CT,X-ray and fluoroscopy.Pregnant women are not recommended.MRI is generally considered safe.But in the first three months of pregnancy does not give an exact answer to the question of fetal safety.Gadolinium contrast enhancement needs to be noticed during pregnancy,which is associated with increased risk of rheumatic immune disease,inflammation,invasive skin disease,stillbirth,or neonatal death.In general clinic,it is generally recommended to avoid MRI examination in the first three months of pregnancy,and MRI enhancement should be prohibited during pregnancy.An enhancement scanning is not recommended for children under one year of age.

五、磁共振检查前准备及需要知道的小细节.Preparation and Details you need to know before MRI scanning.

1.一般情况下您不需要做特别准备。但是因为您将进入的检查室有一个强大的磁场,所以需要遵循安全流程。您绝对不能携带任何非固定的金属物品,例如珠宝,因为这会导致严重的安全问题。而且您将会被问及是否做过和金属植入物相关的手术,如身上是否有外科夹钳,或用于骨折修复的螺丝钉,或已植入的心脏起搏器。如果这些物件存在于您的体内,在扫描过程中会发生问题。

2.检查过程中噪音很大。你可能会听到很大的噪音,像一台冲击钻在施工,音量高达82~118分贝,所以最好提前戴上耳塞。一些人尤其是小孩子也许会受到惊吓,因此他们需要服用镇静剂来安静地接受检查。当然已有静音磁共振设备,但是估计普及到各个医院还需要一段时间。

3.检查时间也许比你预期的长。标准的检查程序只有20分钟左右,但有可能被拉长到一个小时。磁共振技师会建议患者在检查前去趟卫生间。

4.你可能会感到焦虑。有些人会在接受检查时感到恐惧或焦虑,类似幽闭恐惧症的感觉。所以最好在进入机器前先闭上眼睛,在整个过程中不要睁开。你不妨想像一些比较有趣的事情,或者你喜欢的人或宠物。有的人需要服用抗焦虑的药物。

5.最好不要化妆。有些化妆品中含有金属,它们会与磁场发生反应。所以检查当天不要化妆,包括指甲油、止汗药、防晒霜等,最好护发产品也不要用。

6.让医生了解你的文身情况。在检查过程中,文身中的颜料会加热,导致皮肤受到刺激甚至灼伤,遮盖也不管用。检查中如果皮肤有刺激感,应立刻停止。

7.可能感觉热。在无线电波的作用下,体表温度可能会升高1摄氏度左右,因此有些人会在检查过程中感到热。这时不要担心,保持冷静。

8.别乱动。如果你在检查过程中移动了,就得重新做一遍。

9.不必担心放射线辐射。核磁共振使用的是强大的磁场和无线电波,没有X射线,因此不用担心辐射危险。

1.Usually very little.But there are certain safety procedures as you will be inside a strong magnet.You must not have any loose metal on you such as jeweler as this could cause serious problems.Also,you will be asked if you have had any operations in the past where any metal was used.For example,if you have surgical clips,or screws used to fix fractures,or a pacemaker fitted.If these are still in your body they can cause problems during the scanning process.

2.There is a lot of noise during the inspection.You might hear a lot of noise,like a percussion drill in construction,with a volume of 82 to 118 decibels,so it's best to wear earplugs during imaging.Some people,especially children,may be frightened,so they need to take sedatives sometimes.

3.The imaging time may be longer than you expect.The standard procedure is only about 20 minutes,but it can be stretched to an hour.

4.You may feel anxious.Some people feel fear or anxiety when they are examined,similar to claustrophobia.Some people need to take anti-anxiety medications.

5.Don't wear makeup.Some cosmetics contain metals that react with the magnetic field.So don't wear makeup on the day,including nail polish,antiperspirant,sunscreen,etc.Don't use the hair conditioner.

6.Let the doctor know about your tattoo.During the inspection,the pigment in the tattoo maybe will heat up,causing the skin to be irritated and even burn.Check that if the skin is irritant,stop immediately.

7.It may feel hot.With radio waves,the temperature of the body may rise by about 1 degree Celsius,so some people will feel hot during the inspection.Don't worry,stay calm.

8.Don't move during scanning.If you move during imaging,you have to do it again.

9.Don't worry about radiation hazard.MRI powerful magnetic fields and radio waves,without x-rays,so there is no danger of radiation.

六、MRI扫描可能会产生并发症吗?Are there any possible complications?

MRI扫描是安全的。不像X线和CT检查,MRI扫描无电离辐射损害,然而:

有一种可能的严重并发症是强大的磁场会导致过去手术中遗留的金属夹或缝合发生移动,这就是为何您会被问及过去手术的情况。

在罕见的情况下,有些人会对造影剂过敏。一旦出现过敏,我们会立即为您采取有效的治疗。

对孕妇的建议是如果情况不紧急尽量不要做MRI检查。尽管扫描被认为是安全的,但强磁场对胎儿发育的长期影响仍未可知。

MRI scans are painless and safe.Unlike x-rays and CT,MRI does not carry the risks of exposing the patient to ionizing radiation.However:

A possible serious complication is the strong magnetic field can cause movement of a metal clip or stitch from a previous operation where these have been used.This is why you will be asked about previous operations.

Rarely,some people have an allergic reaction to the contrast dye which is sometimes used.This can usually be treated immediately.

Pregnant women may be advised not to have an MRI scan if it is not urgent.Although the scan is thought to be safe,the long-term effects of strong magnetic fields on a developing baby are not yet known.

七、在MRI扫描后应当注意些什么?What can I expect after an MRI scan?

MRI扫描不会对您产生即刻影响,因此您可以在检查结束后正常开展日常活动。但是如果您在扫描时使用了镇静剂,则需有人陪同您回家,因为只有等到镇静剂药效消失后您才能驾驶。放射科医生会阅读扫描图像,然后给您的主诊医生发送影像学报告。

There are no after effects form the scan.So,you can return to your normal activities as soon as the scan is over.However,if you had a sedative for the scan you will need someone to accompany you home.You will not be able to drive until the effect of the sedative wears off.The pictures from the scan are studied by a radiologist(Medical Imaging Doctor)who sends a report to the doctor who requested the scan.

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吕玉波
吕玉波 副主任医师
好大夫工作室 医学影像科
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