Chapter 17 - Computed Tomography Scan

Abstract

A computed tomography (CT) scan is an imaging modality that uses rotating x-ray beams and detectors to produce high-quality cross-sectional imaging of anatomic structures. Compared with standard radiography, CT scans produce images with higher-contrast resolution that allows for improved tissue differentiation and characterization. However, it is also more expensive and exposes patients to significantly more ionizing radiation than standard radiography. It has numerous clinical indications and is often used in the diagnosis of medical emergencies. Iodinated contrast media (ICM) may be administered during a CT scan to further enhance radiographic differentiation. Allergic-like reactions to modern ICM are rare. However, patients with a history of a prior allergic-like reaction to ICM are at the highest risk and require corticosteroid premedication. Although less common than previously believed, administration of intravenous ICM to patients with an estimated glomerular filtration rate <30 mL/minute/1.73 m2 or acute kidney injury may result in contrast-induced nephropathy.