Cerebral hypoperfusion in medication resistant, depressed patients assessed by Tc99m HMPAO SPECT.

Functional imaging studies generally show decreased cerebral metabolism and perfusion in depressed patients relative to normal controls, although the location of the deficits varies. We used Tc99m HMPAO SPECT to compare cerebral blood flow in medication resistant, depressed patients and a normal control group. HMPAO uptake ratios (adjusted for age) were significantly lower in the depressed patients in the transaxial slices 4 cm and 6 cm above the orbitomeatal line (OML) on the left side. Examining individual regions of interest (corrected for age and multiple testing), we found significantly lower perfusion in the left superior temporal, right parietal and bilateral occipital regions in the patient group. These findings are in limited agreement with previous HMPAO SPECT studies. Methodological differences between studies, particularly variability in adjusting data for age, lead to a divergence in findings. Future research should seek to standardize protocols and data analysis in order to generate comparable results.