PET, SPECT surpass clinical tests for AD

How well a patient counts, remembers word lists, or performs other basic tests may not indicate how far Alzheimer's dementia has progressed biologically, according to a study presented at the RSNA meeting.

The Mini-Mental Status Exam has been the standard diagnostic tool for Alzheimer's disease for years, relying on a series of simple cognitive tests to calculate a score for degree of mental impairment. In 58 patients who also underwent PET or SPECT imaging, however, the MMSE showed little correlation with imaging evidence of advanced disease.

Many patients with near-normal MMSE scores showed pronounced bilateral defects on imaging, while others with extremely low MMSE scores showed only moderate PET or SPECT perfusion defects, according to Amitha Rao, a third-year medical student at the University of Kansas, who completed the research under the direction of radiologist Dr. Reginald Dusing.