June 17, 2004
Medicare, the government's insurance program for seniors, is soon expected to cover a specialized form of brain scan called PET to aid in the early diagnosis of Alzheimer's disease. The procedure may help doctors make a diagnosis of Alzheimer's in some people in the early stages of memory loss. Final approval is expected in the next 90 days, following a period in which the government is hearing comments from the public.
The PET procedure may help doctors determine if someone is suffering from Alzheimer's. Confirming a diagnosis as early as possible is important for many patients and caregivers, who must begin planning for the future. It may also allow someone who is suffering from early Alzheimer's to begin taking medicines, such as Aricept, Reminyl, or Exelon, that may slow disease progression in some people during the early stages of mental decline.
It is important to note, however, that a PET scan is just one additional instrument in the Alzheimer's diagnostic toolbox. Determining that someone actually has Alzheimer's requires careful examination by a doctor to rule out other possible causes of memory loss. Before a PET scan is even considered, a doctor must conduct a series of mental tests to look for signs of memory loss or mental decline. Other scanning techniques, such as MRI (magnetic resonance imaging) or CAT scans, may also be done to look for areas of poor blood flow, tumors, strokes, or other brain defects that may explain a patient's symptoms.
In many cases, a doctor can make a probable diagnosis of Alzheimer's based on the person's history, clinical exams, mental and psychological tests, and other procedures. The PET scan procedure may be useful in difficult cases, when the diagnosis remains uncertain. People must have had memory loss and/or other symptoms suggestive of Alzheimer's for at least six months. They must also have had a thorough medical workup to look for medical disorders other than Alzheimer's, such as depression or a stroke, that may be causing the mental decline.
The PET procedure has previously been approved for diagnosis of other ailments, such as heart disease and lung cancer. However, many private insurers do not cover it for the diagnosis of Alzheimer's disease. A move by Medicare to cover it may lead to increased coverage by private insurers.
If you are considering a PET scan, talk with your doctor. The test must be conducted by a specially trained radiologist or technician at an accredited medical center. It is also expensive, costing around $1,500. Local malls or shopping centers may offer "virtual scanning" and other procedures, but these might not be covered by insurance or provide the necessary expertise.
In the current report, issued by the Centers for Medicare and Medicaid Services, which administers the government's Medicare and Medicaid programs providing health services to seniors, children, the poor and disabled, experts recommend the PET procedure be done by an M.D. who is certified in either Neurology, Psychiatry, Geriatrics, Internal Medicine, or Family Practice. They also recommend that you look for a doctor who specializes in Alzheimer's and other forms of dementia.
What You Can Expect
PET, or positron emission tomography, is a non-invasive scanning procedure that measures body processes like blood flow and metabolism in various organs, including the brain. The person undergoing the scan first receives an injection of a radioactive tracer. After you enter a special scanning machine, radiation detectors record the emissions of the radioactive substance. The information is then relayed to a computer, which creates color-coded, cross-sectional images depicting areas of the brain. PET scans provide valuable information not just about the structure of the brain, but about activities going on in certain areas of the brain.
The PET test can take from 1 to 2 hours, and except for a few needle-sticks is generally painless. You will first be asked to lie down on a table, and one or two intravenous (IV) lines are placed in the veins or your arms. It's important not to drink alcohol, beverages containing caffeine, smoke, or take sedatives or sleeping pills a day beforehand, as these may interfere with test results.
A radioactive material is then fed through the IV line, and a doctor or technician slides the patient into the PET scanning machine. It's important to remain as still as possible. In order to minimize distractions, you may wear an eye cover or earplugs. Special cushions will be placed against your head to help keep it still. As the test proceeds, the doctor may ask you to add or subtract numbers or remember a sequence of words.
Afterwards, you may feel a little faint or dizzy, so stand up slowly. You can leave the medical center and resume your day-to-day activities once you feel okay. Drink lots of fluids to help flush the radioactive tracer from your body. Only small amounts of radiation are used, not enough to be considered generally dangerous, though experts caution that you should avoid unnecessary radiation and so should not have a PET scan unless it will provide additional helpful information.
A radiologist will have your test results within a day or so. You can discuss results and next steps with your doctor.
Centers for Medicare & Medicaid Services, "NCA Tracking Sheet for Positron Emission Tomography (FDG) and Other Neuroimaging Devices for Suspected Dementia" (CAG-00088R).
Centers for Medicare & Medicaid Services, Medicare Coverage Database, Draft Decision Memo for Positron Emission Tomography (FDG) and Other Neuroimaging Devices for Suspected Dementia (CAG-00088R