什么是核磁共振?

磁共振成像, 或核磁共振, 是否有一种非侵入性医学成像测试可以产生人体几乎所有内部结构的详细图像, 包括器官, 骨头, 肌肉和血管. MRI scanners create images of the body using a large magnet and radio waves. No ionizing radiation is produced during an MRI exam, unlike X-rays. 这些图像给你的医生诊断你的身体状况和计划一个疗程的重要信息.

What to Expect During 你r MRI Exam at Johns Hopkins 医学成像

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核磁共振扫描是如何工作的?

核磁共振成像仪很大, 圆柱形(管状)机器，在推荐十大正规网赌平台周围产生强磁场，并从扫描仪发出无线电波脉冲. Some MRI machines look like narrow tunnels, while others are more open.

核磁共振扫描仪产生的强磁场使你体内的原子向同一方向排列. 然后从核磁共振成像仪发出无线电波，将这些原子移出原来的位置. 因为无线电波被关掉了, the atoms return to their original position and send back radio signals. 这些信号被计算机接收并转换成被检查身体部位的图像. This image appears on a viewing monitor.

MRI may be used instead of computed tomography (CT) when organs or soft tissue are being studied. MRI能更好地区分不同类型的软组织以及正常和异常的软组织.

因为没有使用电离辐射, there is no risk of exposure to radiation during an MRI procedure.

磁共振成像的新用途促进了其他磁共振技术的发展. 磁共振血管造影(MRA) is a procedure used to evaluate blood flow through arteries. 核磁共振成像也可以用来检测脑动脉瘤和血管畸形——脑血管的异常, 脊髓或身体的其他部位.

功能性磁共振成像(fMRI)是用来确定大脑中某个特定功能所在的特定位置, 比如演讲或记忆, 发生. The general areas of the brain in which such functions occur are known, but the exact location may vary from person to person. 在大脑的功能磁共振成像中, you will be asked to perform a specific task, such as reciting the Pledge of Allegiance. By pinpointing the exact location of the functional center in the brain, doctors can plan surgery or other treatments for a brain disorder.

我该如何准备核磁共振检查?

吃/喝: 你 may eat, drink and take medications as usual for most MRI exams.  There are some specialty MRI exams that require certain restrictions. 当您安排检查时，约翰霍普金斯医学影像公司将为您提供详细的准备说明.

服装: 你 will be asked to remove all clothing, including underwear, 把所有私人物品锁好. Please remove all piercings and leave all 珠宝 and valuables at home.

期待什么: 成像是在一个两端开放的大管状结构内进行的. 你 must lie perfectly still for quality images. Due to the MRI machine's loud noise, earplugs are required and will be provided.

过敏一些核磁共振检查需要静脉造影剂. If you have had an allergic reaction to MRI contrast, contact your ordering physician to obtain the recommended prescription. 你可能会在考试前24小时、12小时和2小时口服这种药物.

抗焦虑药物: If you require anti-anxiety medication due to claustrophobia, contact your ordering physician for a prescription. 你 must bring your prescription on the day of your appointment. Please note that you will need someone to drive you home.

强磁环境由于强磁场, 如果你体内有任何金属，你必须在预约之前通知你的医生. 需要详细的资料, 如类型和位置, 来确定你是否有资格做核磁共振. If you have metal in your body that was not disclosed before your appointment, 你的学习可能会耽误, 在您到达后重新安排或取消，直到获得更多信息.

根据您的医疗状况，您的医疗保健提供者可能需要其他准备.

当你打电话预约的时候, 如果你有以下任何一种情况，通知你的医生是非常重要的:

• 你 have a pacemaker or have had heart valves replaced.
• 你 have any type of implantable pump, such as an insulin pump.
• 你 have vessel coils, filters, stents, or clips.
• 你 are pregnant or think you might be pregnant.
• 你有过枪伤吗.
• 你 have ever worked with metal (for example, as a metal grinder or welder).
• 你 have metallic fragments anywhere in the body.
• 你 are not able to lie down for 30 to 60 minutes.

How do I prepare for specialized MRI studies?

 在某些情况下, 我们将在考试前与您联系，讨论考试程序的细节以及如何准备.

专门的核磁共振检查包括:

• 乳房核磁共振成像
• 乳房活组织检查 通过核磁共振成像
• MRI动态骨盆/排便造影
• MRI肠造影
• 功能磁共振成像
• 磁共振血管造影(MRA)
• 前列腺MRI成像

在核磁共振检查过程中会发生什么?

MRI扫描可以在门诊进行，也可以作为住院的一部分. Although specific protocols may differ among facilities, an MRI procedure generally follows this process:

• 你 will be asked to remove all clothing, 珠宝, 眼镜, 助听器, 发夹, removable dental work or other objects that may interfere with the procedure.
• 你会得到一件长袍.
• If you are to have a procedure done with contrast, 在手或手臂上开始静脉注射造影剂. 如果造影剂是口服的，你会被要求吞下.
• 你将躺在扫描台上，扫描台上滑进扫描机的一个大的圆形开口. Pillows and straps may be used to prevent movement during the procedure.
• The technologist will be in another room where the scanner controls are located. However, you will be in constant sight of the technologist through a window. 扫描仪内的扬声器将使技术人员能够与你交流并听到你的声音. 你会有一个交流球，这样你就可以让技术人员知道你在手术过程中有任何问题. 技术人员会一直看着你，并与你保持联系.
• 医生会给你戴上耳塞或耳机，帮助你屏蔽扫描仪发出的噪音. 有些耳机可以播放音乐.
• 扫描过程中, 当产生磁场和从扫描仪发出无线电波脉冲时，会发出咔嗒声.
• It will be important for you to remain very still during the examination, as any movement could cause distortion and affect the quality of the scan.
• 时间间隔, you may be instructed to hold your breath or not breathe for a few seconds, depending on the body part being examined. 你 will then be told when you can breathe. 你 should not need to hold your breath for longer than a few seconds.
• 如果使用造影剂，当注射到静脉管线时，您可能会遇到一些影响. These effects include a flushing sensation or a feeling of coldness, 咸味:口中的咸味或金属味, 短暂的头痛, 瘙痒, 或者恶心和/或呕吐. These effects usually last for a few moments.
• 你 should notify the technologist if you have any breathing difficulties, 出汗, 麻木或心悸.
• 一旦扫描完成, the table will slide out of the scanner and you will be helped off the table.
• 如果静脉注射是为了注射造影剂，那么静脉注射线将被移除.

While the MRI procedure itself causes no pain, 在整个手术过程中必须躺着不动可能会引起一些不适或疼痛, particularly if you had a recent injury or invasive procedure, 比如手术. 技术人员将使用所有可能的舒适措施，并尽快完成程序.

核磁共振检查后会发生什么?

从扫描台上起身时应动作缓慢，以避免在手术过程中平躺引起头晕或头晕.

如果在手术过程中服用了镇静剂，你可能需要休息，直到它们消失. 你还需要避免开车.

如果在手术过程中使用了造影剂，并且您对造影剂有任何副作用或反应, 比如瘙痒, 肿胀, 约会后出现皮疹或呼吸困难，立即打电话给医生. If you feel it is a life threatening emergency, call 911. 

如果你感到疼痛, redness and/or 肿胀 at the IV site after you return home, 你应该通知你的医生, as this could indicate an infection or other type of reaction.

Otherwise, no special type of care is required after an MRI scan. 你可以恢复你平常的饮食和活动，除非你的医生有不同的建议.

根据你的具体情况，你的医生可能会在手术后给你更多或其他指示.

If you are a patient at 约翰霍普金斯医学院, 你应该在预约后三四天在我的病历上看到你的核磁共振检查的最终报告. (Note: 你 must sign up for MyChart to have access to your medical records.)

A Child’s MRI without Anesthesia – Johns Hopkins Pediatric 放射学

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Is your child about to have an MRI exam? 孩子们可以从鳍鱼那里学到他们需要知道的关于去约翰霍普金斯大学做核磁共振扫描的一切. 你r child’s MRI exam may or may not use anesthesia. 这段视频解释了在约翰霍普金斯大学进行无麻醉儿童核磁共振扫描的过程.