John- It makes me happy to hear that you will be seeing another doctor. Dede shared a site that you should look at about PET scans. The difference between a PET scan and CT is its purpose.

A CT scan can be used to visualize nearly all parts of the body and is used to diagnose disease or injury as well as to plan medical, surgical, or radiation treatment.

A PET scan can help reveal the metabolic or biochemical function of your tissues and organs. The PET scan uses a radioactive drug (tracer) to show both normal and abnormal metabolic activity. Cancer throws off energy and the radioactive injection will light up on the scan indicating that something is injured or needs further attention, like cancer.

I will be very interested to hear what your new doctor has to say. Your appointment is this Monday, right?