A CAT scan uses computer enhanced X-rays to create a cross-sectional image of the anatomy. There are several different scans: the Brain Scan, Abdomen Scan, and Chest Scan. Patient preparation varies depending upon which scan is being made. During the actual scan, patients lie still and may be asked to hold their breath from time to time. CT Brain Scan For a scan such as this, patients will be given an I.V. injection of "contrast media"-a solution that can be seen by the scanner. This scan takes a total of about 30 minutes. CT Abdomen Scan Before this scan, patients are given contrast media to drink, and then an I.V. injection of more contrast media. This test takes from 30 to 45 minutes to complete. CT Chest Scan Patients in a CT Chest Scan are given an I.V. injection of contrast media before the scan, which takes 15 to 20 minutes. For more information of CT Scans, please visit this site.