At United Radiology Group, a majority of CT exams are performed either with IV contrast or without, while just a few exams are performed both with, and without, IV contrast.
When a CT scan is performed both without and with contrast, we are essentially doing two scans through the patient. We have CT scanning protocols in place to assist with determining how patients should be scanned. These protocols are directed and set by the radiologists who are the acting medical directors of the radiology department and are accredited by the American College of Radiology.
The suggested appropriateness criteria for all radiological exams including CT are offered forth by the American College of Radiology.
Download: CT Protocols Revised 2017