A multiphase CT scan is a contrast-enhanced computed tomography exam that acquires images at several timed phases (typically arterial, portal venous, and delayed) after IV contrast injection. It shows how tissues and lesions enhance over time, improving detection and characterization of tumors, vascular abnormalities, and liver or pancreatic disease, and aiding treatment planning and surgical decision-making.

Multiphase scanning is a contrast-enhanced CT protocol that acquires images at several timed phases—noncontrast, arterial, portal-venous and delayed—after contrast injection. Comparing enhancement patterns across phases improves detection and characterization of lesions (liver, pancreas, kidneys) and vascular anatomy, aiding diagnosis, staging and treatment planning. It involves ionizing radiation and iodinated contrast, which carry small risks like allergic reaction and kidney injury.

Multiphase CTA (computed tomography angiography) is a contrast-enhanced CT technique that acquires multiple timed image sets—typically arterial, venous, and delayed phases—to visualize blood vessels and tissue perfusion. It improves detection and characterization of vascular disease (stenosis, aneurysm, dissection), active bleeding, stroke and tumor vascularity, and guides diagnosis, treatment planning and endovascular interventions.

A CT liver multiphase scan is indicated to detect and characterize focal liver lesions by imaging arterial, portal venous, and delayed contrast phases. It’s used for diagnosing hepatocellular carcinoma, metastases, hemangiomas and vascular lesions, for preoperative staging and surgical planning, assessing trauma, and for monitoring post-treatment or ablation response. Multiphase timing improves lesion conspicuity and vascular detail.

The three common types of CT scans are: 1) Non-contrast CT — images acquired without contrast, useful for detecting bleeding, fractures, stones; 2) Contrast-enhanced CT — IV or oral contrast improves visualization of organs and tumors; 3) CT angiography (CTA) — timed contrast study focused on blood vessels to detect blockages, aneurysms, or clots. Choice depends on the clinical question.

A CT scan typically involves three phases: non-contrast (pre-contrast) imaging to assess calcification, hemorrhage, and baseline anatomy; arterial (early post-contrast) phase to visualize arterial supply and hypervascular lesions; and venous or portal-venous (later post-contrast) phase to evaluate venous structures, parenchymal enhancement, and most tumors. Timing depends on the clinical indication.