(CECT) Contrast agents are used during contrast enhanced computed (or computerized) tomography examinations to highlight specific tissues and parts of the body. Bones can be clearly seen on x-ray images, the visualization of some other organs and soft tissues is more difficult. Sufficient contrast is important in perceiving a difference in the density between areas of a CT image. The identification of a disease may be challenging due to very low contrast between pathological tissues (for example tumors, metastases and abscesses), normal organ structures and surrounding tissues.
Contrast agents are used in CT angiography (CTA) to delineate vessels, in multiphasic CT studies to provide dynamic information of blood supply (e.g., liver CT) and in CECT studies of various body parts to achieve opacification of tissue of interest (e.g., kidney CT) in relation to the background tissue. Contrast enhanced multi-detector row CT (MDCT) replaces several conventional diagnostic imaging methods such as intravenous urography, cholangiography, or catheter angiography, due to advanced CT studies with fast examination times, high contrast enhancement, perfusion measurement and multiplanar reformatting capabilities.
See also Contrast Media Injector, Single-Head CT Power Injector, Multi-Head Contrast Media Injector, Syringeless CT Power Injector, CT Power Injector.

Contrast media injectors are part of the medical equipment used to deliver fluids in examinations such as CT, MRI, fluoroscopy and angiography. Many of these diagnostic imaging procedures include the administration of intravenous contrast agents to enhance the blood and perfusion in tissues.

Mainly there are two types of injector technology:
See also Single-Head Contrast Media Injector, Dual-Head CT Power Injector, Syringeless CT Power Injector.

The use of x-ray contrast agents in computed tomography (CT) began with a hand injection by the radiologist in the scan room. During its history, CT scanners have made great improvements in speed and image quality. Actual CT systems with multiple detectors allow scan times of a few seconds per body region. Some CT protocols require multiphase scans, where a body region is imaged with a single bolus of contrast in different blood flow phases. Automatic power (pressure) contrast media injectors are required to provide precise control of flow rate, volume and timing of injection. The use of a saline bolus following contrast administration reduces the volume of contrast required.

Most relevant topics for the use of a power injector in medical imaging procedures such as contrast enhanced computed tomography (CECT):
Must have basic injector control options:
Examples of other injector control options:

Contrast-induced nephropathy is a serious complication of intravascular x-ray contrast agents. The osmolality of the contrast medium is an important fact in contrast-induced nephropathy and should ideally be iso-osmolar to blood. Today, nonionic contrast agents are state of the art for vascular use, the ionic contrast agents caused more adverse reactions.
Signs of contrast-induced nephropathy after the application of vascular contrast agents are a serum creatinine increase of 0.5 mg/dL (In the United States, creatinine is typically reported in mg/dL, while in Canada and Europe µmol/L may be used. 1 mg/dL of creatinine is 88.4 µmol/L) or an increase of serum creatinine greater than 25%.

A higher risk of contrast-induced nephropathy is associated with:
The use of a nonionic contrast agent, iso-osmolar to blood and a low dose reduces the risk for contrast-induced nephropathy.

A coronary angiogram (or cardiac catheterization) is the radiographic visualization of the coronary arteries after the introduction of a contrast agent. A coronary angiography can be performed for both diagnostic and interventional (treatment) purposes.
A catheter, inserted into a major blood vessel has to be maneuvered up to the coronary arteries to inject a blood compatible iodinated contrast material (dye). The x-ray visible catheter allows injecting a small amount of contrast agent selectively in the coronary arteries or the heart chambers. Continuous images are recorded (movies or cineangiogram) in multiple views from different angles are in order to ascertain the precise location and severity of coronary artery blockages. Digitized images are also saved on computer and replayed onto a video screen as needed.
A coronary angiogram is more invasive and requires more patient recovery time than coronary CT angiography. In the past, the gold standard for detecting atherosclerotic plaque was a coronary angiography and intravascular ultrasound. Today, the American Heart Association considers CT scanning to be one of the most effective, non-invasive methods for the detection of calcification in the coronary arteries.

See also Interventional Radiology.

The couch increment is the distance by which the position of a patient table is changed between individual slices. In spiral CT scanning the couch increment is the change of the table position during one 360° rotation of the x-ray tube.