Objective: The authors hypothesized that there is a pattern difference in cerebral perfusion of the 99-Technitium L, L-ethyl cysteinate dimer Single Photon Emission Computer Tomography (99-Tc ECD SPECT) between mild and moderate to severe dementia.

Material and Method: The authors reported a retrospective study in the Memory Clinic, Siriraj Hospital between January 2001 and October 2003 including only patients with Alzheimer’s disease, vascular dementia, and mixed dementia. Clinical dementia rating (CDR) was used to document dementia severity. Patterns of hypoperfusion were classified into no definite hypoperfusion, regional hypoperfusion, and diffused hypoperfusion.

Results: One hundred and seven patients were included in the present study. Only mean Thai Mental State Examination (TMSE) score was different between the two groups. There was no significant correlation between pattern of hypoperfusion in brain SPECT and severity of dementia.

Conclusion: The authors cannot demonstrate the pattern of hypoperfusion of 99-Tc ECD SPECT among patients’ difference in dementia severity.

Keywords: SPECT, Dementia, Thai