CT扫描

定义

A computed tomography (CT) scan is an imaging method that uses x-rays to create pictures of cross-sections of the body.

相关测试包括:

• 腹部及骨盆CT扫描
• 头颅或头部CT扫描
• 颈椎，胸椎，还有 腰骶椎CT扫描
• 眼眶CT扫描
• 胸部CT扫描
• CT血管造影

选择的名字

CAT scan; Computed axial tomography scan; 计算机断层扫描 scan

如何执行测试

You will be asked to lie on a narrow table that slides into the center of the CT扫描ner.

Once you are inside the scanner, the machine's x-ray beam rotates around you. Modern spiral scanners can perform the exam without stopping. 噪音很小.

A computer creates separate images of the body area, called slices. These images can be stored, viewed on a monitor, or copied to a disk. Three-dimensional models of the body area can be created by stacking the slices together.

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

完整的扫描通常只需要几分钟. The newest scanners can image your entire body in less than 30 seconds.

如何准备考试

某些检查需要一种特殊的染料, 叫对比, to be delivered into your body before the test starts. Contrast helps certain areas show up better on the x-rays.

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 avoid another reaction.

Contrast can be given several ways, depending on the type of CT being performed.

• It may be delivered through a vein (IV) in your hand or forearm.
• 你可以在扫描前喝些造影剂. When you drink the contrast depends on the type of exam being done. The contrast liquid may taste chalky, although some are flavored. The contrast passes out of your body through your stools.
• Rarely, the contrast may be given into your rectum using an enema.

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.

静脉注射造影剂前, tell your provider if you take the diabetes medicine metformin (Glucophage). People taking this medicine may need to stop temporarily. Also let your provider know if you have any problems with your kidneys. 静脉造影剂会使肾功能恶化.

Find out if the CT machine has a weight limit if you weigh more than 300 pounds (135 kilograms). 重量太大会损坏扫描仪.

You will need to remove jewelry and wear a gown during the study.

考试的感觉如何

Some people may have discomfort from lying on the hard table.

Contrast given through an IV may cause a slight burning feeling, 嘴里有金属的味道, 还有温暖的身体潮红. These sensations are normal and usually go away within a few seconds.

为什么要进行测试

A CT扫描 creates detailed pictures of the body, including the brain, chest, spine, and abdomen. 该测试可用于:

• 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

正常的结果

Results are considered normal if the organs and structures being examined are normal in appearance.

异常结果意味着什么

Abnormal results depend on the part of the body being studied. Talk to your provider about questions and concerns.

风险

CT扫描的风险包括:

• 对造影剂过敏
• 造影剂对肾功能的损害
• 暴露于辐射

CT扫描s expose you to more radiation than regular x-rays. Having many x-rays or CT扫描s over time may increase your risk for cancer. 然而，任何一次扫描的风险都很小. You and your provider should weigh this risk against the value of the information that will come from a CT扫描. Most new CT扫描 machines have the ability to reduce the radiation dose.

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. 如果你对碘过敏，对比剂可能会导致 恶心或呕吐, 打喷嚏, 瘙痒, or 荨麻疹.
• 如果你一定要给这样的对比, your provider may give you antihistamines (such as Benadryl) or steroids before the test.
• 肾脏帮助排出体内的碘. You may need to receive extra fluids after the test to help flush iodine out of your body if you have diabetes or kidney disease.

Rarely, 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 immediately. Scanners come with an intercom and speakers, so the operator can hear you at all times.

参考文献

布兰肯斯坦JD，莱利RJ. 计算机断层扫描. 见:Sidawy AN, Perler BA编. Rutherford's Vascular Surgery and Endovascular Therapy. 10日艾德. Philadelphia, PA: Elsevier; 2023:chap 29.

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 Imaging. 7日艾德. Philadelphia, PA: Elsevier; 2021:chap 47.