When you learn that PET stands for Positron Emission Tomography and CT stands for computed tomography, you understand why we simply call it a PET CT or PET. This exam has become a critical tool for physicians to gauge how advanced a cancer is and to assess the best way to treat that cancer.
PETs scans are precise. They measure the extent of disease to a much greater degree than any other tool physicians currently have. They work particularly well in assessing lymphoma, malignant melanoma, breast, lung, colon and cervical cancers.
How PET Works
PET imaging or a PET scan, is a type of nuclear medicine imaging. In nuclear medicine, we use small safe amounts of radioactive material to diagnose or treat disease. This is a noninvasive procedure that is usually painless.
Depending on your type of exam, you swallow, inhale or are injected with a radiotracer. A radiotracer is a radioactive substance added to your metabolic system in a very small quantity. The PET machine can trace or follow the substance through your system. A complicated set of equipment measures the amount of radiotracer absorbed by your body and produces special pictures with details of the structure and function of your organs and tissues.
A PET scan measures critical functions like blood flow, oxygen use, and sugar (glucose) metabolism. These measurements help your physician and radiologist evaluate the health and well-being of your organs and tissues.
Today, we perform PET scans on instruments that combine PET and CT scanners. The combined PET CT scans provide images that pinpoint the location of abnormal metabolic activity within the body and offer a more accurate diagnoses than the two scans performed separately.
Why Physicians Use PET
Unlike other imaging techniques, PET scans and other nuclear medicine imaging studies are less directed toward picturing anatomy and structure. They are more concerned with depicting physiologic processes within the body – the rate of metabolism or levels of various other chemical activity, for example. Areas of greater intensity, called “hot spots”, indicate where large amounts of the radiotracer have accumulated and where there is a high level of chemical activity. PET scans are typically used to:
- Detect cancer
- Determine whether cancer has spread
- Assess the effectiveness of a treatment plan
- Determine if a cancer has returned after treatment
- Evaluate brain abnormalities for seizure disorders and dementia
- Detect heart disease (for example, sarcoidosis)
Preparing For Your PET Scan
You may be asked to wear a gown during the exam or you may be allowed to wear your own clothing. Women should always inform their physician or technologist if there is any possibility that they are pregnant or if they are breastfeeding. Also let your physician and the technologist know about:
- Medications you are taking
- Any allergies
- Recent illnesses or other medical conditions, specifically diabetes
You will receive specific instructions based on the type of PET scan you are undergoing. If you are a diabetic, you will also receive special instructions.
For the exam to function properly, you must remove any metal objects including jewelry, eyeglasses, dentures and hairpins. You may also be asked to remove hearing aids and removable dental work. It’s also very important that you do not eat or drink anything except for water for 6 hours before your exam because it could interfere with the results; don’t even chew gum. If you take medications, drink only water to swallow them.
What a PET Scan is Like
In most cases, a PET scan and other nuclear medicine imaging exams are performed on an outpatient basis. Please plan on at least two hours in our office with 30 minutes of that time devoted to the actual scan.
You will be positioned on an exam table. A nurse or technologist will insert an intravenous (IV) line into a vein in your hand or arm to inject the radiotracer. It takes about 60 minutes for the radiotracer to travel through your body and be absorbed by the organ or tissue being studied. You will rest quietly, avoiding movement and talking.
You will then be moved into the PET/CT scanner and the imaging will begin. You should not feel a thing during the scan.
Please remain still during imaging. The CT exam will be done first, followed by the PET scan. You may be asked to wait 15 minutes after the scan has been completed for a technologist to give you a CD of your exam.
Unless your physician tells you otherwise, you may resume your normal activities after your PET scan. If any special instructions are necessary, you will be informed by a technologist, nurse or physician before you leave the facility.
Benefits & Risks
Your physician and our radiologists only recommend a PET when it is essential. The information the scan provides is unique and often unattainable using any other imaging procedure. For many diseases, a PET yields the most useful information for correct diagnosis and for best determining treatment. By identifying changes in your body within cells, PET imaging may detect the early onset of disease before it can be discovered with other imaging tests.
With the more detailed and dependable data a PET provides, treatments tend to be shorter and yield better long-term health results.
The benefits of a combined PET/CT scanner include greater detail with a higher level of accuracy. Since Radiology & Imaging performs both scans at one time without you changing positions, there is less room for error. And taking two tests at once is more convenient for you.
The risks are small. Diagnostic nuclear medicine procedures result in low radiation exposure. Nuclear medicine diagnostic procedures like PET scans have been used for more than five decades. There are no known long-term adverse effects from low-dose exposure.
Allergic reactions are extremely rare and usually mild. But do inform the technologist of your allergies or any problems you had during a previous nuclear medicine exam.
Limits of PET
The clarity of a PET image may not be as crisp as with CT, MRI or other imaging technique. However, nuclear medicine exams like PET scans are more sensitive than other techniques for a variety of health indicators. And the functional information gained from a PET scan is often unobtainable by any other imaging exam.
Being on time for your appointment is important. The radioactive substance used in PETs decays quickly and is effective for only a short period of time. For the exam to work you need to receive the radioactive material at the scheduled time.
We Subspecialize In Reading PET Images
We use high-resolution, state-of-the-art PET CT equipment. The diagnostic detail our equipment provides is exceptional. Having a radiologist, like ours, who subspecializes in reading PET CT images means more expertise and experience is at work for you.
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