Pictures of Brain Activity
Doctors can get some idea of how much amyloid plaques have encroached on healthy brain tissue by taking sophisticated pictures of brain activity, which can highlight where nerve cells are becoming weaker and starting to deteriorate and may eventually affect brain function.
Computed tomography (CT) scans provide details that differentiate between fat, fluid, soft tissue, bone, and air. Doctors may use CT scans to make sure that a person with memory problems does not have a tumor or evidence of a stroke.
Positron emission tomography (PET) yields an image of brain metabolism and reveals where brain nerve cells engage the healthy activities of their daily function. These images can show changes in brain function. A radioactive substance is injected into the bloodstream and unstable atoms released from the radioactive substance collide with electrons in body tissue, releasing gamma rays. The gamma rays are collected into an image of where cells are most active.
This real-time technique allows doctors to see whether any areas of the brain have stopped functioning due to Alzheimer’s.
By combining a PET and CT scan the researcher can see how much activity your brain has and compare it with structural information. In Alzheimer’s dementia, the level of brain activity decreases. This decrease also corresponds with areas of nerve cell loss.
In 2004, researchers at the University of Pittsburgh reported for the first time that an agent named Pittsburgh compound B (PiB) could bind to amyloid. Using PiB during a brain scan to enhance the images may alert doctors to the presence of protein plaques before symptoms of Alzheimer’s appear. PIB glows when patients’ brains are scanned with PET. One in five elderly persons who do not have cognitive impairment or memory problems show brain deposit of amyloid similar to levels found in individuals who have Alzheimer’s. Why these persons have been able to escape the symptoms of Alzheimer’s remains an important scientific question. Still not widely used, PIB could become a useful addition to the panel of factors that doctors consider when diagnosing the disease.
These scans can show areas where groups of nerve cells have died due to Alzheimer’s. MRI images are most useful in identifying areas where nerve cells have begun to die off, a sign that Alzheimer’s may be progressing.