PET/CT scan. You need to fast for 4 hours first, then you will recieve an injection of a small amount of radioactive glucose (i.e. Sugar). Next you will sit in a recliner chair for about 70 minutes to allow the glucose to distribute throughout you. Then you will lie on your back on the pet/ct scanner (a tunnel shaped machine) for 20 minutes. There are no side effects from the test or restrictions afterwards.
Physiology. First, follow all of the directions given to you by the imaging center re pet appt. That usually means no strenuous activity for 24 hours before the scan time, nothing to eat after midnight, etc. The scan uses an injection of radioactive, sterile fluid, like a blood test in reverse. You sit quietly for 1 hour and are scanned for about 20 min. The scanner is like a ct, not as tight as a mri.
Together in 1 machne. A pet scan measures the uptake of glucose. The uptake of glucose is increased in most cancers. A ct scan is a basically a series of xrays over the area of interest which provides superb anatomic detail. If a ct scan picks up a mass, it may not be able to tell if it is cancerous or benign. Combining the information with the pet scan allow for superior sensitivity and specificity in detecting tumors.