头部CT扫描

定义

一个头 计算机断层扫描 (CT) scan uses many x-rays to create pictures of the head, 包括头骨, 大脑, 眼眶, 和鼻窦.

选择的名字

Brain CT; Cranial CT; CT scan - skull; CT scan - head; CT scan - orbits; CT scan - sinuses; Computed tomography - cranial; CAT scan - 大脑

如何执行测试

Head CT is done in the hospital or radiology center.

You lie on a narrow table that slides into the center of the CT scanner.

While inside the scanner, the machine's x-ray beam rotates around you.

A computer creates separate images of the body area, called slices. 这些图像可以是:

• 存储
• 在显示器上查看
• 胶片印刷
• 保存到磁盘

Three-dimensional models of the head area can be created by stacking the slices together.

You must be still during the exam, because movement causes blurred images. You may be told to hold your breath for short periods.

A complete scan usually takes only 30 seconds to a few minutes.

如何准备考试

Certain CT exams require a special dye, called contrast material. It is delivered into the body before the test starts. Contrast helps certain areas show up better on x-rays.

• Contrast can be given through a vein (IV) in your hand or forearm. 如果使用对比, you may also be asked not to eat or drink anything for 4 to 6 hours before the test.
• Let your health care provider know if you have ever had a reaction to contrast. You may need to take medicines before the test in order to safely receive it.
• 在接受对比之前, tell your provider if you take the diabetes medicine metformin (Glucophage). 你可能需要采取额外的预防措施. Also let your provider know if you have any kidney function problems as the IV contrast can worsen this problem.

If you weigh more than 300 pounds (135 kg), find out if the CT machine has a weight limit. 有些机器可以.

You will be asked to remove jewelry and may need to wear a hospital gown during the study.

考试的感觉如何

The x-rays produced by the CT scan are painless. Some people may have discomfort from lying on the hard table.

Contrast material given through a vein may cause a:

• 轻微的灼烧感
• 口中有金属味
• 身体温热潮红

This is normal and usually goes away within a few seconds.

为什么要进行测试

一个头 CT scan is recommended to help diagnose or monitor the following conditions:

• Birth (congenital) defect of the head or 大脑
• 大脑感染
• 脑瘤
• 头盖骨内积液(脑积水)
• Injury (trauma) to the 大脑, head, or face
• 中风
• 颅内或周围出血

It may also be done to look for the cause of:

• 儿童头部大小异常
• 思想或行为的变化
• 晕倒
• Headache, when you have certain other signs or symptoms
• 听力损失(部分人)
• 大脑部分受损的症状, 比如视力问题, 肌肉无力, 麻木和刺痛, 听力损失, 说话困难, 或者是吞咽问题

异常结果意味着什么

异常结果可能是由于:

• 血管异常(动静脉畸形)
• 脑血管膨大 (动脉瘤)
• 出血(例如， 硬脑膜下血肿 或者脑组织出血)
• 骨感染
• 脑脓肿 或感染
• 由于受伤造成的脑损伤
• 脑组织肿胀或损伤
• 脑瘤或其他生长(肿块)
• 脑组织丢失 (脑萎缩)
• 脑积水
• 听力神经有问题
• 中风或 短暂性脑缺血发作 (TIA)

风险

CT扫描的风险包括:

• 暴露在辐射中
• 对造影剂过敏
• 对比染料对肾脏的损害

CT scans use more radiation than regular x-rays. Having many x-rays or CT scans over time may increase your risk for cancer. However, the risk from any one scan is small. You and your provider should weigh this risk against the benefits of getting a correct diagnosis for a medical problem.

有些人对造影剂过敏. Let your provider know if you have ever had an allergic reaction to injected contrast dye.

• The most common type of contrast given into a vein contains iodine. If a person with an iodine allergy is given this type of contrast, 恶心或呕吐, 打喷嚏, 瘙痒, or 荨麻疹 可能发生.
• If you absolutely must be given such contrast, your provider may give you antihistamines (such as Benadryl) or steroids before the test to prevent an allergic reaction.
• The kidneys help remove iodine from the body. Those with kidney disease or diabetes may need to receive extra fluids after the test to help flush the iodine out of the body.

In rare cases, the dye may cause a life-threatening allergic response called 速发型过敏反应. If you have any trouble breathing during the test, tell the scanner operator right away. Scanners come with an intercom and speakers, so someone can hear you at all times.

注意事项

A CT scan can reduce or avoid the need for invasive procedures to diagnose problems in the skull. This is one of the safest ways to study the head and neck.

Other tests that may be done instead of a head CT scan include:

• 头部MRI
• 正电子发射断层扫描(宠物头部扫描

参考文献

Barras CD, Bhattacharya JJ. Current status of imaging of the 大脑 and anatomical features. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. 格兰杰 & 艾利森诊断放射学. 7日艾德. Philadelphia, PA: Elsevier; 2021:chap 53.

陈国强，张国强. 脑计算机断层扫描-诊断. 见:陈国强，张国强编. 实验室测试和诊断程序. 6日艾德. St Louis, MO: Elsevier Saunders; 2013:310-312.