PET is short for Positron Emission Tomography, and it's one of the newer imaging studies that is helping to change the detection and treatment of cancer and Alzheimer's disease. PET was first used in research over 50 years ago. Now the technology of PET has been married to the technology of X-ray Computed Tomography (CT) to make the new PET/CT scanner. Diagnostic Radiology Consultants brought the first PET scanner to the Chattanooga area over six years ago and has performed more PET scans and PET/CT scans than any other local radiology group.

Most PET scans are done on a PET/CT scanner which does a PET scan and a low-dose CT scan on the same machine. This allows the merging of the metabolic PET image with the anatomic CT image to give better detection and location of abnormal accumulation of FDG. The CT data is actually used to make the PET image look better by a process called attenuation correction. This same improved computer software allows the PET images to be merged with other imaging studies such as MRI.

How is a PET Scan Done?

PET scans use radioactive tracers made from radioisotopes. The radiotracer used most is 2-Fluorine-18 fluoro-2-deoxyglucose, or FDG. Individuals having the scan are given an intravenous injection of FDG after they have fasted for 4 hours. Fasting helps decrease the level of glucose (sugar) in the blood, which in turn increases the amount of FDG the cells in the body will use. Once the FDG is in the cells, it is changed by the cells and becomes trapped in the cells. One hour after being given FDG, the patient is ready for the scan. The scan takes 15 to 30 minutes on the new PET/CT scanners. The scan is then processed and sent to the Radiologist for interpretation who sends a report to the referring physician.

How is the PET Scan Used?

The PET/CT scan information is used by physicians to detect, stage, evaluate treatment and follow cancers. Most cancers will use more sugar than normal tissue due to increased metabolism. This increased uptake of FDG allows the PET scan to identify locations of cancers and possible spread or metastasis. The metabolic information helps to detect smaller cancers and metastases that are often not seen on other imaging studies. The PET scan also shows if the cancer metabolism is decreased after cancer therapy. This will allow the treating physician to know if the therapy is working much earlier than other imaging studies which usually look only at the size of the cancer. PET scans can also detect the reoccurrence of cancer earlier, especially in tissue that is scarred or deformed from prior treatments.

PET scans are now used in neurology to scan for dementias such as Alzheimer's disease. Brain cells are very active and use large amounts of glucose. Brain tissue that has been damaged by disease or stroke will have decreased metabolism and thus have a decreased uptake of FDG. The pattern of decreased uptake of FDG can be used to make the diagnosis of Alzheimer's disease and some other neurological disorders at earlier stages than CT or Magnetic Resonance Imaging (MRI) scans. Although there is no cure for Alzheimer's disese at this time, early treatment helps to delay the progression of the disease and increases the functional status of the patient.

Making an Appointment

When you call, we'll ask you for basic information such as your Social Security number. We'll ask you what type of test you need to schedule, and will schedule you for the best possible time. If you need to reschedule your exam, you can call us back and we'll be happy to arrange a better time for you.

When you call to schedule your exam, we'll also give you important information about preparing for the exam. If your doctor has scheduled the exam for you, and you have questions regarding the preparation or the procedure itself, you can call the imaging department where your procedure is being performed (please refer to our 'Locations' page for exact phone numbers).

Your physician will have several tasks to perform:

Complete the necessary paperwork to order the test (similar to writing a prescription for medication)

Fax, mail, or place the order in our computer system

Call us to schedule a test for you or have your physician call us directly

Obtaining Your Images

Exam Image Availability

DRC's state-of-the-art PACS technology offers you immediate access to the images of your radiologic exam. No longer does your physician have to wait to have copies of your films made. Although we can still print your X-ray on film for you with just 24 hours notice, your physician can now review your exam images immediately via the Internet. We offer safe and secure web access for your physician through Specialty Networks. Your privacy and HIPAA compliance is assured.

Images on a CD

If your physician prefers, the digital images from your study can be written to a CD-ROM, giving him/her a permanent record that can be accessed easily and quickly via a computer. CDs hold multiple studies and take up significantly less space than the traditional film in the brown envelope. A 24-hour notice is also requested to create this digital record for you.

Versatile Image Viewing Options

Internet access to your studies for your doctor is available immediately after your pictures are taken. Copies of your images can be obtained on a CD or on film with 24 hours notice.

Both Internet and CD viewing offer your physician the ability to digitally adjust your images in ways not possible with traditional X-ray film. Using the computer, the image can be made lighter or darker or zoomed for better visualization of a particular portion, for example. Your physician can fine-tune the images to accommodate his or her preferences.

Obtaining Copies of Your Images

To receive a CD or film copies of exam images, please follow these steps:

1. Call the location where your examination was performed (please refer to the locations page). Please provide your name and other identifying information along with the study being requested. With 24 hours notice, we can either create a CD-ROM or print a film for you. Our representative at the imaging center will provide you with the times available to pick up the exam.

2. To protect your privacy, please be sure to bring a picture ID when you pick up your CD/films, you will have to sign a Medical Images Release form when receiving your CD/films. If anyone else picks up your CD/films for you, please be sure to give him or her your written authorization to release your information to him or her.

3. If you would like us to send a copy of your study to a physician outside the DRC system, we will need a signed release from you along with the study you would like sent and the receiving doctor's name and address. You can fax or deliver us that release in the form of a signed letter at the fax number listed on the locations page. Please allow us plenty of time to send your films.

Any Costs

Currently the first set of films is provided at no cost to the patient. There is no charge for CD-ROM's and, of course, the Internet is always free.


For the convenience of our patients, we offer Imaging Scans at several DRC locations:

Battlefield Imaging
Chattanooga Outpatient Center
Diagnostic Center
Diagnostic PET/CT of Chattanooga
Hutcheson Medical Center
Tennessee Imaging & Vein Center