Alzheimer's Disease takes a terrible toll on patients and their families. In the past, its diagnosis has been elusive because it mimics the symptoms of other forms of dementia. Diagnosis was generally made by ruling out other causes but a definitive confirmation could only be made by an autopsy.

As frustrating as this uncertainty was for both patient and family, it did not significantly impact care for the simple reason that relatively few treatment options were available. Today, however, there is a new class of drug therapies having great success in slowing the onset of Alzheimer's symptoms in some patients. With the hope of delaying symptoms for as much as a year, the urgency to more accurately distinguish Alzheimer's from other diseases has become an important first step in determining the right treatment for patients with dementia.

In September, 2004, Medicare approved the use of PET scanning for Alzheimer's, citing the growing body of evidence that the technology has proven its ability to accurately diagnose this devastating disease. PET, short for Positron Emission Tomography, is a molecular imaging procedure that shows the biological changes that occur in the brain when Alzheimer's is present. These changes occur very early on in the disease when treatment can have its greatest impact.

A normal brain uses a large amount of sugar or glucose as fuel. PET provides a picture of this activity. In contrast, the brain of an Alzheimer's patient has a distinct pattern of altered function caused by the presence of amyloid plaques and neuro-fibrillary tangles which over time kill brain cells. What the PET image shows is a lack of glucose in these areas.

To be eligible for Medicare reimbursement, a patient must show a documented decline in cognitive function for 6 months, have undergone a mental status exam by their doctor, have had other possible causes like brain tumor ruled out with MRI or CT and still lack a clear diagnosis. Of course, a patient may always choose to pay for the procedure themselves, provided they have referral from their physician.

For more information on PET/CT click on technology. If you already have a PET/CT scheduled, click here for exam preparations.