BACKGROUND: The aim of this study was to assess the accuracy of visual image rating as compared to parametric analysis of regional cerebral blood flow (rCBF) measured with SPECT in patients referred to a memory clinic for diagnostic evaluation of cognitive symptoms. METHODS: SPECT with (99m)Tc-HMPAO was used to determine rCBF in 47 patients and 26 healthy control subjects. The 47 patients (30 F/17 M) had a mean age of 74.6 years (range = 62-88) and mild or questionable dementia with an MMSE score of 24.8 (range = 20-30). Two experienced image readers blinded to the classifications and identity of subjects performed visual rating in consensus and the global and regional CBF patterns were evaluated and graded according to severity of hypoperfusion. Correlation coefficients were calculated using results from the parametric analyses as gold standard. RESULTS: The sensitivity and specificity of global visual rating (normal vs. abnormal SPECT) was 92 and 86%, respectively, yielding an overall accuracy of 89% for visual rating compared to parametric analysis. The correlation between visual rating and parametric analysis was highly significant (p < 0.001). CONCLUSION: Visual rating is a valid method for analyzing SPECT images in patients with mild or questionable dementia.