As a stage 3, my doctor recommended alternating liver ultrasound, CAT Scan and MRI every six months. However, the recommendation was to screen for liver cancer and not to diagnose cirrhosis or attempt to stage liver fibrosis. Currently, I'm choosing to just do ultrasound and MRI because CAT scan involves more radiation.
Mike, earlier posted an article from the Mayo Clinic, that suggests the same. The last two posts in the thread are the relevant ones:
http://www.medhelp.org/forums/Hepatitis/messages/42020.html
In part it reads:
"The last and most conclusive way to diagnose cirrhosis is a liver biopsy. A physician removes a tiny sample of liver tissue and examines it under a microscope. The procedure can be conducted using a needle biopsy technique that typically requires only local anesthesia."
Another interesting article is by Dr. Nezam Afdhal, a leading hepatologist and researcher into the dx of fibrosis/cirrhosis using non-invasive techniques. He is the head of the current Fibroscan trials in the U.S. It is interesting to note that he doesn't even mention CAT scan in this article:
http://www.natap.org/2005/HCV/080905_01.htm