What is computed tomography?

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Computed tomography (short: CT) is a modern and powerful examination with x-rays. This method acquires cross-sections of the body. Computed tomography can provide very detailed pictures of different organs like brain, lung, liver, pancreas and kidneys. With these pictures it is possible to define location and extent of lesions. Computed tomography is based on x-rays, consequently it is usually not used during pregnancy. If you are (possibly) pregnant, please tell us before the exam.

What is to know?

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All metals cause some interferences. Therefore you have to take off all accessoires in the examination area that contain metal e.g. hairpins, dental protheses, bra, chains. Belts and zippers of trousers and skirts can stay.

Drinking contrast agent:

For examination of the abdomen, you should drink one liter of water. This helps us to distinguish between areas in and outside the bowels. Rarely, oral contrast agent is used in stead of water.

Lab results:

Contrast agent can have side effects, for example renal failure and hyperthyroidism. Please bring the following lab results: creatinine (not older than 4 weeks) and TSH (not older than 3 months). If TSH is too low, please bring T3 and T4 as well.

How is the exam done?

Contrast agent administration:

Depending on the clinical question it may become necessary to inject contrast agent into the blood stream. Therefore a cannula is placed in one of your arm veins. The contrast agent is injected using a power injector.

Because the contrast agent is eliminated from the body through the kidneys, normal kidney functions are a prerequisite.

During contrast medium injection, you may feel transient feeling of warmth and a metal taste which is self-limiting without any side effects.

As with any other medication, an allergic reaction to contrast agent may occur. Minor reactions include slight breathing difficulty, cough, and skin rashes and usually do not require any treatment. However major reactions like allergic shock may require active treatment and resuscitation. Most major reactions occur during a few minutes after the start of the injection and immediate treatment is necessary which is readily provided by the attending doctor and his team.

Buscopan injection:

Some CT examinations require bowel relaxation, for which Buscopan is injected. After injection, there may be slight transient difficulty of vision and dizziness. Therefore, it is recommended that you do not drive a car afterwards.

Contra indication to Buscopan injection is elevated eye pressure (glaucoma) or prostate hyperplasia. If you have cardiac problems (tachycardia) please tell us in advance.

What is the examination procedure?

The exam lasts for approximately 10 minutes and is painless.

The steps of the exam are:

• you will lay down on a table which moves slowly through the scanner with a gantry diameter of 80 cm and a length of 40 cm.

• body movements during the exam degrade image quality. Therefore, you should stay relaxed and do not move. You should breath normally unless asked specifically to follow breathing instructions.

• The examination is performed in multiple breath holds to minimize artefacts caused by respiratory movements. The person performing the examination will give you breathing instructions. If you follow the instructions, a good quality examination is achieved. For the specific investigation of heart and big vessels, ECG monitoring will be necessary during the examination. After the examination, you will go back to the waiting area. A technical assistant will remove the cannula unless it is necessary for other investigations being planned on the same day.

Images / Report:

A radiologist will review your images and send the report to your attending doctor.

Technical information about the CT Scanner

Our department offers you a high-end dual source dual energy CT scanner (Somatom Definition FLASH, Siemens). Two x-ray tubes rotate around the patient, which allows fast examination times. A thorax scan can be performed in 0.6 seconds, a heart scan in even 250 ms. Whole body imaging lasts about 5 seconds. The spectral information from the dual energy CT can be used to visualize tumor perfusion and to characterize tumor texture. Compared to older scanners, this CT can reduce radiation exposure, e.g. by automated x-ray modulation.

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