The CT scanner is like a large donut-shaped x-ray machine with a hole, or short tunnel, in the center. You will lie on a narrow examination table that slowly move into and out of this tunnel. It rotating around you, the x-ray tube and electronic x-ray detectors are located opposite each other in a ring, called a gantry. The computer workstation that processes the imaging information is located in a separate control room, where the radiographer operates the scanner and monitors the examination. The radiographer will still be able to communicate with the patient, and vice-versa, through an intercom.
A CT scan is not painful but lying still on the table during the procedure may be a little uncomfort. During the scan, the x-ray machine may make soft buzzing, clicking and whirring sounds. All Diagnostic CT exams last from fifteen to forty-five minutes, depending on the extent of the study being performed.
CT and MRI are very different and used for different needs and reasons; both are valuable and both have specific applications; they are not interchangeable and one is not a better test than the other for all things.
CT scanning is useful to get a very detailed 3-D image of certain parts of the body, such as soft tissues, the pelvis, blood vessels, the lungs, the brain, abdomen, and bones.
It is often the preferred method of diagnosing many cancers, such as liver, lung, and pancreatic cancers. The image allows a doctor to confirm the presence of a tumor. The tumor's size can be measured, plus its exact location, as well as to determine how much the tumor has affected nearby tissue.
A scan of the head can provide the doctor with important information about the brain (whether there is any bleeding, swelling of the arteries, or tumors).
A CT scan will tell the doctor whether the patient has a tumor in his/her abdomen, and whether any internal organs in that area are swollen or inflamed. It will reveal whether there are lacerations of the spleen, kidneys or liver.
As a CT scan can detect abnormal tissue it is a useful device for planning areas for radiotherapy and biopsies.
A CT scan can also provide valuable data on the patient's vascular condition. Vascular refers to blood flow. Many vascular conditions can lead to stroke, kidney failure, and even death. It can help a doctor asses bone diseases, bone density, and the state of the patient's spine.
A CT scan can reveal vital data about injuries to the patient's hands, feet and other skeletal structures - even small bones can be seen clearly, as well as their surrounding tissue.
1) CT is very good for imaging bone structures.
2) Some patients who have received certain types of surgical clips, metallic fragments, cardiac monitors or pacemakers cannot receive an MRI.
3) The time taken for total testing is shorter in CT than for MRI.
4) MRI cannot be done in patients who are claustrophobic as the patient has to remain inside the noisy machine for about 20-45 minutes
5) It is more economical than an MRI, the cost of an MRI scan tends to be higher than for a CT scan.
6) Patient might option for CT is if they have metal implants in their body, since these often mean that an MRI is impossible.