Positron Emission Tomography PET is different from a Computed or computer assisted Tomography CT/CAT Scan dramatically. PET is accomplished by administering Glucose (IV Drip) and then injecting a radioactive isotope. You are then left in a darkened room for one hour for the isotope to reach cellular level. they then take you to a CT scanner or a new faster 32 slice CT, the total body scan lasts about 1 hour. When the scan is read the cancer cells light up due to the fact that cancer cells (mutant cells)metabolize sugars differently than healthy cells.
But, let me stress, that it takes a highly trained individual to read a PET scan, there are a LOT of false positives, especially when dealing with lymphatic tissue.
They are a priceless tool for detecting early stage tumors but are vague with metastatic lymphatic disease.
Darrell