CT scanning

[placebo_B12]

What is the difference between a contrast CT scan and a CTA?

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[rad_one]

A contrast enhanced CT is a generic term used when IV contrast is administered to exaggerate contrast differences between structures. This can be timed to evaluate organs/structures in various phases of enhancement (arterial, venous, delayed, etc). A CT angiogram (CTA) is specifically timed and designed to evaluate aterial flow in the location of interest- chest to eval for PE, extremity exams, circle of willis, and others.

 

[Docxter]

What is the difference between a contrast CT scan and a CTA?

CTA is a CT exam in which the contrast injection timing, injection rate, scanning delay time, and in high-end institutions injection rate curve and saline chase have been optimized to visualize the vessels. Also the CT technique parameters are again chosen to optimize visualization of the arteries and make 3D reformats easier. Therefore CTA is often not the way to evaluate many parenchymal organs for contrast enhancement. Sometimes the parameters are optimized to look at the veins. CT perfusion is another technique in which extremely high flow rates of contrast are injected to assess many different parenchymal perfusion parameters, for example in the brain, to determine cerebral blood flow, blood volume, and mean transit time. CTA parameters are different for looking at different arteries (e.g., pulmonary, brain, feet). SOmetimes the timings are modified to match the patient's circulation time (cardiac output, etc.), often required for children or CHF patients.