contrastCT

Contrast-enhanced computed tomography, or contrast CT, is a CT imaging technique in which iodinated contrast material is administered to improve visualization of vascular structures and tissue differences. The contrast increases attenuation in selected areas, helping to delineate blood vessels, organs, and lesions. Imaging can be single-phase or multiphase, including arterial, venous, and delayed phases, depending on the clinical question. CT angiography is a common application that focuses on arterial anatomy and pathology.

The contrast agent is typically an iodinated medium given by intravenous injection, often with a programmable power injector. In some protocols, oral or rectal contrast may be used to opacify the gastrointestinal tract. Modern CT scanners and automated injectors allow precise timing of image acquisition to capture specific enhancement phases. The choice of contrast, flow rate, and timing depend on the suspected condition and patient factors.

Indications for contrast CT include evaluation of acute abdominal pain, suspected appendicitis, diverticulitis, bowel ischemia, trauma, pulmonary embolism, stroke, and cancer staging. It is also used for CT angiography to assess arterial or venous vessels and for infection or inflammatory processes where enhancement patterns aid diagnosis. Non-contrast CT may be used when contrast is unnecessary or contraindicated.

Safety considerations include the risk of contrast reactions and contrast-induced nephropathy, particularly in patients with preexisting kidney dysfunction or dehydration. Contraindications include known severe iodinated contrast allergy and markedly reduced renal function. Precautions may involve premedication, hydration, and alternative imaging strategies when warranted.