Neuro-Imaging and Alzheimer's: The Basics

Contributed by: Dennis Fortier, President, Medical Care Corporation
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Rarely a day goes by when I do not see several news items about the role of neuro-imaging in detecting, treating, or monitoring the progression of Alzheimer's disease. Here are a few comments to bear in mind as you consume the daily press.

Magnetic Resonance Imaging (MRI) yields an image of brain structure and will reveal tumors, strokes, and (importantly for Alzheimer's disease) atrophy (or shrinkage) in particular parts of the brain that can be helpful in reaching an accurate diagnosis.

Positron Emission Tomography (PET) yields an image of brain metabolism and reveals where brain cells are engaged the healthy activities of their daily function. In some instances, this can reveal an earlier stage of a problem than MRI would reveal because cells may have stopped functioning but remained intact structurally.

Many news stories report on "tracers" or agents such as PIB that, once injected into the blood, make their way to the brain and bind with the beta amyloid, rendering it clearly visible in the scan. This is important because many scientists believe beta amyloid accumulation may be the cause of Alzheimer's disease.

While the PET/PIB studies are generally promising, public optimism should be tempered by the fact that the PIB compound has some significant practical shortcomings. It decays rapidly and must be injected very quickly after being manufactured. For that reason alone, the prospect of wide-spread use in a clinical setting is a distant one.