Computed Tomography (CT)

Computed Tomography (CT) – Functional Principle

Computed tomography (CT) is an advancement of the traditional X-ray imaging. It has been used in diagnostic radiology since the end of the 1970s. With a CT images are recorded from various directions. The connected computer processes the image data and produces exact pictures of the different tissue layers. Each layer shows the tiniest details of tissue, partially in the submillimetre range. In this way, exact virtual, three-dimensional images of the examined body parts are created. In comparison to the traditional X-ray method, which only produces two-dimensional images, the CT offers an accurate imaging of even the smallest changes, which can be detected very early. At the same time, diagnosis at an early stage of disease can improve the curing prospects. CT makes use of X-rays. However, our ultra-fast multisclice CT scanners are designed with technical specifications reducing the patient’s exposure to radiation. The benefit of the examination should always outweigh the potential radiation risk by far.

Computed Tomography (CT) – Fields of Application

Computed tomography is particularly useful for the investigation of bone and many other organ structures.

Predominantly, CT is used for the examination of (the):

  • head (e.g. suspected brain haemorrhage, tumour, stroke, etc.)
  • skelettal system including spine and joint diagnostics (e.g. disc prolapse, fractures)
  • abdomen (e.g. changes in liver or pancreas, inflammation of the gastrointestinal tract, bile duct disorders)
  • tumours or severe injuries (search for metastases, gathering information) with the help of a whole-body CT scanning

Computed Tomography (CT) – Process of Examination

During CT scanning you will lie on your back or occasionally on your stomach on a soft examination table that slides slowly into the wide circular opening of the CT scanner. It’s not shaped like a long and narrow tube but like a huge ring. That’s the reason why patients rarely mention claustrophobic problems caused by the scanner.

In the course of examination you should feel at ease and lie as still as possible. Please avoid movement, breathe calmly and follow the breathing instructions given by our medical staff. Throughout the whole process of examination our medical staff is at your side, monitoring you from the control room. The procedure usually takes about 10 minutes.

Computed Tomography (CT) – Contrast Agents

The use of an intravenous contrast agent containing iodine, which is injected through a thin plastic catheter into a vein in the arm, can help to improve the quality of diagnostically conclusive images. Please note, that some findings can only be detected after injection of a contrast agent. Sometimes, the radiologist is able to make the decision for applying a contrast medium only after having started the examination.
Additionally, in special examinations of the digestive organs, the patient is asked to drink a contrast agent 0,5 to 3 hours before the procedure.

All of the contrast agents we employ in CT scanning are generally well tolerated.

Computed Tomography (CT) – Risks

During the application of a vein tube or injection of contrast medium:

Rarely: It can cause damage to skin, tissue or nerves. Under certain conditions these permanent consequences are possible: pain, inflammation, tissue necrosis, scars, disturbed sensation / function or paralyses.

After applying an oral contrast medium

Rarely: Symptoms like diarrhoea, flatulence, spasms or nausea or other mild forms of reaction can occur. They usually disappear shortly after treatment.

In case of hypersensitivities to the intravenous contrast agent

Occasionally: Itching, exanthema, nausea, vomiting, diarrhoea and other mild reactions, which tend to quickly subside after the examination.
Very rarely: Strong hypersensitive reaction with respiratory stress, circulatory shock, heart failure, apnoea require intensive care and might cause brain damages or organ failure. Allergic reactions can even appear hours after the injection of the contrast agent.
Very rarely: In case of pre-existing diseases of the kidney or thyroid: Impared renal function, which may lead to kidney failure and dependence on dialysis. Or hyperthyroidism (in the worst case: thyrotoxic crisis). Usually, these disorders can be treated efficiently with infusions or special medication.

In case of a special CT-guided virtual colonoscopy

Very rarely: Injuries of the colon due to an intestinal tube which administers air, water or contrast medium by enema.

Computed Tomography (CT) – Radiation Exposure

Your attending physician and radiologist will weigh up the benefits and risks of a CT scanning carefully. The radiation dose is device-specific and differs according to the body region under examination.
A CT scan of the thorax (lung, breast, skelettal system) can lead to an increased radiation exposure to the mammary gland. Therefore, an elevated risk of breast cancer in children and young women can’t be excluded. Furthermore, an increased cancer and leukaemia risk in children and teenagers can’t be totally excluded either. If repeated CT scans of the head are necessary, there will be a higher risk of cataract (“clouding“ of the lense). In case of pregnancy the radiation exposure caused by the CT scan could harm the unborn child. Please inform us, if you are pregnant or a pregnancy is assumed.

Computed Tomography (CT) – Alternatives

Non-invasive diagnostic alternatives to computed tomography can be ultrasound examination (sonography), magnetic resonance imaging (an imaging technique providing tomographic images using a magnetic field and radio waves) or scintigraphy (recording of radoactive signals after application of small amounts of low-level radioactive substances). Colon enema with contrast agent, colonoscopy or small intestine diagnostics using a contrast medium.

Computed Tomography (CT) – Contraindications

Significant contraindications have to be considered for CT scans carried out with contrast agents. This is particularly the case (for):

  • known hypersensitivity to contrast agent or iodine
  • hyperthyroidism
  • impared renal function
  • If you undergo a diabetes therapy with anti-diabetic medications like metformin, you’re not allowed to take them two days before and after the CT scan depending on your creatinine values (they usually serve as a marker for normal kidney function).

CT examinations are offered at the following locations of RUHRRADIOLOGIE: Our practices in Dortmund, Witten and Ennepetal.