What Are the Types of CT?

CT classification criteria and bases are numerous; however, the most commonly used classification method is based on the type of examination performed. This is also the classification most frequently encountered by the general public, with the following common types:

1. Non-contrast CT (Plain CT): Many patients have undergone this type of CT scan. Typically, physicians order a plain CT, which refers to a CT examination performed without intravenous contrast medium.

2. Contrast-enhanced CT: As the name implies, contrast-enhanced CT requires the administration of a contrast agent to increase the CT density of specific tissues. This involves intravenous injection of iodinated contrast medium specifically formulated for CT.

3. CT Angiography (CTA): While similar to contrast-enhanced CT in requiring intravenous contrast injection, CTA differs in its objective—namely, to visualize relatively large arteries or veins. Due to this distinct imaging goal, the contrast injection protocol—including both dosage and injection rate—differs between CTA and standard contrast-enhanced CT.

4. CT Three-Dimensional (3D) Reconstruction: CT 3D reconstruction utilizes raw data acquired during CT scanning, which is transferred to a post-processing workstation for advanced image processing. Common techniques include sagittal and coronal reconstructions, volume rendering, and virtual endoscopy.