What is the difference in a CT scan and a PET scan?

I had a ct scan and it showed a demarcated mass in my left pelvis so my doctor ordered a PET scan. Could the ct scan mistake my ovary for a mass????Help any advice would be grateful!!

In simple terms, a CT(computed tomography) shows your dr. a picture of what your body looks like on the inside. They can see what is/isn't there, the size and position of structures, and if there is air, fluid, or foreign materials present. A dr. would not mistake an ovary for a mass, he/she has been trained to identify all the organs & knows what they should look like and where they should be. A demarcated mass is one that has clearly defined margins, this could represent a multitude of completely benign things including a cyst(fluid filled cavity lined with normal epithelial cells), an abscess(a puss filled cavity lined with normal epithelial cells), a teratoma(normal tissue that grew in the wrong place), a hematoma(collection of blood), an enlarged/swollen ovulatory follicle, etc. It could also be something more serious but a benign cause is usually far more likely. A PET(positron emission tomagraphy) scan will show your dr. any structures that "light up" during the scan. Only tissues that are rapidly metabolizing energy sources(nutrients) or actively dividing(mitotic activity) will light up. Rapid and unregulated cell division/reproduction is a key characteristic of cancer cells. PET scans are useful for identifying rapidly dividing tissues, areas of high metabolic activity, cancerous tumors, and metastatic disease without the need for invasive procedures. Your best plan of action is to wait for the results of your pet scan, maintain clear and open communication with your doctor, and stay calm.

The CT scans are taken to gain anatomic information. It tells them where things are and whatnot. A PET scan gives them more detailed metabolic information. Basically they look at the CT and if something looks abnormal, they sometimes run a PET scan to see what it's doing biochemically. It tells them if there are abormal cells present and at what rate they're multiplying, etc.

CT-scan is like a bunch of x-ray slices that show bone, tissue, water and air. They are used to show the anatomy of structures in the body. there is no way any even mildly competent radiologist could mistake your ovaries for a mass.
PET scanning works at a molecular level to show the biological changes that cause the physical changes seen on CT.