April 20, 2001

WESTPORT (Reuters Health) - Single photon emission computed tomography (SPECT) can increase the likelihood of an accurate diagnosis of Alzheimer's disease, according to a report in the April 10th issue of Neurology.

Dr. William Jagust, from the University of California Davis Medical Center, and colleagues prospectively collected clinical data and SPECT images on 70 patients with dementia, who were followed to autopsy. In addition, they collected data on 14 control subject subjects who were followed to autopsy and on 71 controls on whom no autopsies were performed.

Analysis revealed that among all the patients and controls, a clinical diagnosis of probable Alzheimer's disease was associated with an 84% likelihood of pathologic Alzheimer's disease.

Using SPECT imaging, the likelihood of Alzheimer's disease was raised to 92% when the SPECT scan was positive. If the scan was negative the likelihood of Alzheimer's disease was reduced to 70%, Dr. Jagust's group reports.

When the clinical diagnosis was possible Alzheimer's disease, the likelihood of Alzheimer's disease was 84% when SPECT imaging was positive and 52% when it was negative. Without SPECT the likelihood of Alzheimer's disease among these patients was 67%, the investigators note.

The use of SPECT to increase the likelihood of a correct diagnosis of Alzheimer's disease may be essential because "some potential therapeutic options (eg., antiamyloid agents, vaccination, or neural transplantation) might be associated with high risks, necessitating accurate diagnoses," Dr. Jagust and colleagues suggest.

Neurology 2001;56:950-956.