PET scanning can give false results if chemical balances within the body are not normal. Specifically, test results of diabetic patients or patients who have eaten within a few hours prior to the examination can be adversely affected because of altered blood sugar or blood insulin levels.
Disadvantages of PET/CT Scans
Because the radioactive material is combined with glucose and then injected into the patient, this can be a concern for some diabetic patients. Before having a PET/CT scan, a diabetic patient's blood sugar level will be evaluated, and a glucose serum blood test might be administered.
Limitations of a PET Scan
Slow-growing, less active tumors may not absorb much tracer. Small tumors (less than 7mm) may not be detectable. High levels of blood sugar can cause the cells to absorb this normal sugar rather than the radioactive, injected kind.
Concerns about CT scans include the risks from exposure to ionizing radiation and possible reactions to the intravenous contrast agent, or dye, which may be used to improve visualization. The exposure to ionizing radiation may cause a small increase in a person's lifetime risk of developing cancer.
A PET scan is considered to be a safe procedure. It exposes you to around the same amount of radiation that you would receive from the general environment over about three years. The injected radioactive chemicals have a very short lifespan and are removed from the body fairly quickly.
Be certain your healthcare provider knows about all of your medical conditions. Certain factors or conditions may interfere with the accuracy of a PET scan, including: High blood glucose levels in diabetics. Caffeine, alcohol, or tobacco consumed within 24 hours of the procedure.
PET Scans. PET is considered to be a safe exam with no known side effects.
CT scans are far quieter and do not cause hearing problems compared with MRIs. CT scans are also preferable among those who are claustrophobic or anxious because the machine is more open and the X-ray device circles around the patient. The main disadvantage to having a CT scan is that it exposes your body to radiation.
CT scans are quick, painless and generally safe. But there's a small risk you could have an allergic reaction to the contrast dye used and you'll be exposed to X-ray radiation. The amount of radiation you're exposed to during a CT scan varies, depending on how much of your body is scanned.
Not all cancers show up on a PET scan. PET scan results are often used with other imaging and lab test results. Other tests are often needed to find out whether an area that collected a lot of radioactive material is non-cancerous (benign) or cancerous (malignant).
The diagnostic accuracy of PET-CT was 93.5%, and the false positive rate was 6.50%. Among the false positive patients, inflammatory pseudotumor (42.86%) and tuberculoma (36.74%) were the most pathological types.
PET/CT is believed to be the most accurate imaging test available to evaluate lung cancer, colon cancer, breast cancer, melanoma, lymphoma, head and neck cancer, and esophageal cancer. In published research studies, PET has been shown to have an approximately 90% accuracy in many of these cancer types.
Why PET scans are used. An advantage of a PET scan is that it can show how well certain parts of your body are working, rather than showing what it looks like. They're particularly helpful for investigating confirmed cases of cancer, to determine how far the cancer has spread and how well it's responding to treatment.
A PET/CT scan is noninvasive, painless and takes about 30 minutes. Along with providing better imaging data, it notably increases patient comfort and convenience by reducing the number of scanning sessions a patient must undergo. The procedure is covered by private insurance and Medicare.
A CT scan creates a detailed non-moving image of organs, bones and tissues. A PET scan, on the other hand, shows doctors how the tissues in your body work on a cellular level. Other differences include: They use different materials: CT scans pass x-rays through the body to create images.
Delayed adverse reactions to radiographic contrast media are usually cutaneous (reported incidence varies from 1% to 23%) and include rash, skin redness, and skin swelling, sometimes associated with nausea, vomiting, and dizziness, that begin 1 hour or longer (usually 6–12 hours) after the administration of the ...
The amount of radiation is greater than you would get during a plain X-ray because the CT scan gathers more-detailed information. The low doses of radiation used in CT scans have not been shown to cause long-term harm, although at much higher doses, there may be a small increase in your potential risk of cancer.
Most skin reactions are self-limiting and resolve within a week. Management is symptomatic and similar to the management of other drug-induced skin reactions.
Unlike X-rays and CT scans, MRIs don't use any radiation. At Johns Hopkins, we've developed very fast, high-resolution MRIs that can be done in 10 minutes or less. An MRI scanner is a highly specialized machine and may not be available in some imaging facilities or emergency rooms at other hospitals.
Radiation Exposure
With the use of ultrasound, there is no exposure to radiation. However, with a CT scan, there is some radiation exposure, about the same as an average person receives from environmental radiation in 3 to 5 years.
MRI scans are generally considered as providing more accurate imagery and are therefore used for diagnosing conditions associated with your bones, organs or joints. CT scans are often used to identify any bone fractures, tumours, or internal bleeding. Reasons for getting an MRI scan could include: torn ligaments.
The radioactive tracer gives off very small levels of radiation that go away very quickly. As a precaution, you should avoid close contact with pregnant women, babies and young children for 6 hours after the scan. You need someone to take you home and stay overnight if you've had medicine to help you relax (sedative).
Does any radiation stay in the body after an imaging exam? After a radiographic, fluoroscopic, CT, ultrasound, or MRI exam, no radiation remains in your body. For nuclear medicine imaging, a small amount of radiation can stay in the body for a short time.
The specific amounts patients pay vary according to their insurance coverage. Medicare limits the number of PET scans following initial cancer treatment to three per patient. (More could be covered if deemed necessary by the doctor.) “These are good scans and appropriate in many situations,” Healy says.