Computerized Axial Tomography Scan (CT or CAT Scan)
A CT Scan is a procedure that combines many x-ray images with the aid of a computer to generate cross-sectional and three-dimensional views of anatomy. CT Scans are performed to analyze the internal structures of various parts of the body. CT Scans can identify normal and abnormal structures and be used to guide procedures.
CT Scans are preferred for numerous parts of the body including brain, sinus, neck, chest, spine, abdomen, pelvis, and extremities. CT Scans can also be beneficial for evaluating the heart and lungs.
Some CT Scans require contrast material to be injected intravenously, administered by mouth and/or by enema in order to increase the distinction between various organs or areas of the body that have circulation. The intravenous contrast is iodine-based liquid given in the vein. Rarely, are there any adverse reactions to the intravenous contrast. New intravenous contrast agents, such as Isovue have been developed and are used at Radiology and Imaging Specialists to decrease allergic reactions. If the patient has a history of allergy to contrast material, the requesting physician and radiology staff should be notified. Patients that are allergic to iodinated products still may have a CT Scan performed with intravenous contrast. To eliminate complication with the contrast medium an antihistamine may be administered prior to or after the examination. With the intravenous injection patients may feel a warm sensation throughout their body or they may experience a metallic taste in their mouth. This is a normal reaction to the intravenous contrast.
Contrast administered by mouth is called barium. Oral barium is a liquid contrast given to outline the bowel and distinguish the bowel from other local structures with similar attenuation values. Oral barium is to be ingested by the patient one hour prior to the CT examination. Certain CT Scans require the barium contrast medium to be administered rectally by the radiologic technologist.
CT Scans are very low-risk procedures. The amount of radiation the patient receives during a CT Scan is minimal and the results are extremely advantageous. CT Scans provide a clear, accurate display of tissues without superimposition of structures. CT Scans may detect disease processes and lesions at an earlier stage than with conventional imaging. CT Scans provide a wide range of imaging and the technique does not have to be limited to specific organs. CT Scans have vastly improved the ability of doctors to diagnose many diseases earlier in their course and with much less risk than previous methods.
Preparation and Special Instructions
Patients having CT exams scheduled without contrast medium require no special preparation.
In preparation for a CT Scan with the use of intravenous or oral contrast medium, patients are often asked to be NPO (nothing by mouth) four hours prior to having the exam.
Patients who require oral contrast need to arrive one hour prior to their appointment to start the drinking process. It is extremely important to drink plenty of fluids after having a CT study performed with the use of an intravenous or oral contrast medium. Drinking fluids help the body expel the contrast medium through normal body functions.
Patients should continue to take their medications as prescribed. If a woman is pregnant or thinks she might be pregnant, it is important that she informs the referring physician. The patient should also inform the radiologic technologist upon performing the exam.
Please, bring any previous radiology studies and reports that are related to this exam.
What to expect
The CT Scanner is a large donut-shaped machine that acquires images at many different angles around the body. The actual procedure can take from a few minutes to forty five minutes. Patients are asked to please remove all metallic materials, such as jewelry and certain types of clothing prior to having the CT examination performed. These materials may interfere with the clarity of the images. Patients are placed on a movable table and the table is slid into the center of the large donut-shaped machine. It is important during the CT procedure that the patients minimize any body movement by remaining as still and quiet as possible. For some CT Scans, special breathing instructions are required. The radiologic technologist will inform the patient when to breathe or hold his/her breath during the examination. If the CT exam is to include intravenous contrast medium a small IV will be placed by the radiologic technologist. The IV will be removed upon completing the CT Scan. The technologist directly watches the patient through an observation window during the procedure, there is an intercom system in the room for added patient safety and communication. If any problems are experienced during the CT Scan the technologist should be informed immediately.