Technology Increasingly Used in Diagnosis of Alzheimer's Disease

Patient Expert

They have fancy-schmancy names - PET, MRI, CAT and SPECT. These acronyms have become some of the frontline weapons in learning more about Alzheimer's disease and dementia. They are high-tech tools that the medical professionals can use to look at the brain and determine what is right - and more importantly, if you're experiencing cognitive issues - what is wrong.

These tests are just part of the way that Alzheimer's disease can be diagnosed. An evaluation for Alzheimer's disease and mild cognitive impairment also can include:

  • A complete health history and a comprehensive physical examination.
  • Screening for depression.
  • Neurologic testing.
  • Mental status testing.
  • Blood test.
  • Urine test.

So what are these acronyms? Here's goes:

  • Single photon emission computed tomography (SPECT), which is a type of scan that lets health care professionals analyze the function of some internal organs. This scan is a type of nuclear imaging test. A radioactive substance is injected into the body and a special camera then takes pictures to create three-dimensional views. "While imaging tests such as X-rays can show what the structures inside your body look like, a SPECT scan produces images that show how your organs work," the Mayo Clinic website states.
  • Magnetic resonance imaging (MRI), which uses a magnetic field and radio waves to provide detailed images of the body's organs as well as its tissues.
  • Positron emission tomography (PET), which uses a radioactive tracer that is injected into the body to measure how the organs and tissues are functioning.
  • Computerized tomography scan (CT), which combines a series of x-ray views that are taken from different angels and computer processing. This combination creates cross-sectional images of the body's internal views.

So are all of these new-fangled technologies great at identifying the brain changes that take place when mild cognitive impairment or Alzheimer's disease is present? Some experts seem to think "no." An international research team evaluated medical articles that had been published between 1989 and 2012 on the various tests available to assess cognitive problems. The team included doctors from the United States, Italy, France, the Netherlands, Sweden, the United Kingdom, Australia and Canada.

The researchers found that - not surprisingly -- the type of test as well as how the test was performed was tied to how well the test worked in cases of Alzheimer's disease as well as in cases of mild cognitive impairment. They also determined that assessments that were used for diagnosing Alzheimer's disease and mild cognitive impairment were more consistent than assessments that were used for predicting whether the patient who had mild cognitive impairment would develop Alzheimer's disease.

In looking at these assessments, the research team found that amyloid imaging seemed to work better than most assessments. This imaging process enables the detection and quantification of amyloid proteins in the brain. This technique involves using a PET scan to see the amyloid plaques as well as the structural and functional brain changes.

The research team's review of the literature also found that magnetic resonance imaging (MRI) may actually one of the least helpful tests. The research team's finding about this technique was based on the brain's mesial temporal lobe, which is a deep part of the temporal love. This particular brain part is often smaller in people who have Alzheimer's disease. The researchers found that the images created using the MRI to image this region of the brain could result in similar findings among people with Alzheimer's disease as well as people who do not have this cognitive condition.

The researchers also identified major variations in what studies found on specific tests. For instance, a review of the research found mixed results on positron emission tomogram (PET) scans. The research team hypothesized that the widely differing findings might be due to the difference in how individual radiologists read the study.

The researchers suggest these findings indicate that specific "rules" need to be developed about these tests in order to make sure the tests are standardized. This would enable the tests to be more helpful by being used for specific purposes by health professionals.

Primary Sources for This Sharepost:

Karceski, S. (2013). Alzheimer's disease: Which test is best? Neurology.

Mayo Clinic. (2012). CT scan.

Mayo Clinic. (2012). MRI.

Mayo Clinic. (2011). Positron emission tomography (PET) scan.

Mayo Clinic. (2011). SPECT.