THE VALUE OF HMPAO SPECT SCANNING IN THE DIAGNOSIS OF EARLY ALZHEIMERS-DISEASE IN PATIENTS ATTENDING A MEMORY CLINIC

The value of hexamethylpropyleneamine oxime (HMPAO) single photon emis sion computed tomograpy (SPECT) as a diagnostic test for Alzheimer's d isease (AD) was assessed in 44 patients attending a Memory Clinic. A c omprehensive physical and psychiatric examination and detailed neurops ychological tests were used to arrive at a clinical diagnosis, in acco rdance with NINCDS-ADRDA criteria. The mean patient age was 69 (range 59-84) years, and the mean score on the Mini-Mental State Examination (MMSE) was 24 (range 7-30). Of 26 patients with a clinical diagnosis o f AD, only 15 demonstrated a scan pattern strongly suggestive of AD. F our scans were normal, four showed evidence of ischaemic change and th ree were in the category 'other', one of which showed bilateral fronta l hypoperfusion, but normal temporoparietal flow. Of the eight patient s considered by clinical criteria to be non-demented, no scan showed a n AD pattern, but three showed an ischaemic pattern. Both of the patie nts diagnosed clinically as suffering from multi-infarct dementia show ed SPECT scan evidence of ischaemic change. Of the remaining eight pat ients with other clinical diagnoses only one scan suggested AD. We con clude that the HMPAO SPECT scan appearances which arise from AD in the early stages of the disease do not on their own allow the disease to be accurately diagnosed, but they may be useful if interpreted in conj unction with other imaging techniques.