Why does the liver have three phases?
The liver is unique in having a dual blood supply: about a quarter of the blood comes from the hepatic artery and three quarters from the portal vein. Tumors feed primarily from the artery, so in the arterial phase they clearly accumulate contrast, and in the venous phase they are “washed out” - this is a classic sign of hepatocellular cancer. Metastases, on the contrary, are better visible in the venous phase as areas of reduced accumulation. A three-phase study records all these points and at the same time builds a map of the liver vessels - data necessary for the surgeon before resection or transplantation, as well as before chemoembolization.
What is the power of computed tomography?
MSCT creates an image using X-rays and produces thin sections with high spatial resolution. It is indispensable where bone, lung tissue, fresh hemorrhage and precise vessel geometry are important, as well as in emergency situations - the examination takes seconds.
Three-dimensional reconstructions are constructed from the resulting sections: this allows the surgeon to see the anatomy in volume in advance and plan the intervention.
When you need contrast
Intravenous contrast dramatically increases the information content in the study of blood vessels, tumors, inflammatory processes and parenchymal organs. It shows the nature of the blood supply to the formation, which often determines its nature.
Before a contrast study, kidney function is assessed by creatinine level and an allergic history is clarified - reactions to iodine-containing drugs are rare, but require attention.
CT or MRI
- CT scan is better: bones, lungs, acute hemorrhage, stones, vessels, emergency conditions
- MRI is better: brain and spinal cord, soft tissues, joints, pelvis, liver
- CT is faster and more accessible, MRI does not provide radiation exposure
About radiation exposure
Computed tomography uses x-rays and is therefore prescribed according to indications. Modern machines use dose reduction protocols, and the information obtained from sound research usually far outweighs the risk. During pregnancy, CT scans are performed only for health reasons.