Basic question on structure and function. Blood test can tell you how your liver is functioning or if there is any damage occuring. Tests included SGOT, SGPT, Alk Phos, bilirubin, PT, PTT, INR, NH3. Again this is a test of how you liver is functioning. If there is a disturbance of function, then the question is what is causing the disturbance. Can the disturbance be caused by something structural like a stone, a mass, or abcess etc. This is where a CT scan can be useful. CT scan will look at the structure of the liver and can detect structural abnormalities that may be causing the liver blood test abnormalities.
Remember that in medicine we sometimes need more then one test to fully evaluate an organ. And again to evaluate and organ we look at function of the organ and then structure of it. For the lungs – Chest Xray and Pulmonary Function Test. For Kidneys – blood and urine test and CT or U/S. For heart – stress test, ekg, echo. etc

You probably had abnormal liver enzymes via a blood test and the doc is checking for abnormalities of your liver on the scan.He may be looking for tumors or enlargement.Hepatitis’s can be dx with a test and a liver biopsy.Cirrhosis must be dx with a biopsy also.

The most common reason for abnormal liver enzymes can be this so-called fatty liver, which accompanies obesity or pregnancy. Usually, an ultrasound should be sufficient for this kind of diagnosis. you provide very little information, hwich doesn’t really allow to explain why the doctor chose a CT scan versus an ultrasound, which doesn’t use radiation and costs less. there should be more than just abnormal liver enzymes.

The cat scan actually shows if you have any damage to your liver caused by enzymes. Obviously you’ve had some blood work that showed an elevated enzyme count.
The cause can be many things, alcohol, virus, genetics.
You can ask your Dr. for more info