Tc-99m-ECD brain perfusion SPET: variability, asymmetry and effects of ageand gender in healthy adults

Reliable and high-resolution reference data for regional cerebral blood flo w measured with single-photon emission tomography (SPET) are necessary for optimal clinical and research use. Therefore, a large dataset of normal tec hnetium-99m labelled ethylene cysteine dimer (ECD) perfusion SPET in carefu lly screened healthy volunteers with an age range spanning six decades was created, with correction for non-uniform attenuation and scatter and based on an anatomically standardised analysis. Eighty-nine healthy volunteers, s tratified for gender (46 females, 43 males; age 20-81 years), were included . Twelve volunteers underwent repeated Tc-99m-ECD SPET after 2.5 +/-2.3 wee ks. An automated whole-brain volume of interest analysis with MANOVA as wel l as voxelwise analysis using SPM99 was conducted. Average intersubject var iability was 4.8% while intrasubject reproducibility was 3.0%. An age-relat ed decline in tracer uptake was found in the anterior cingulate gyrus, bila teral basal ganglia, left prefrontal, left lateral frontal and left superio r temporal and insular cortex (all P=0.001-0.02). There was an overall incr ease in right/left asymmetry with age, which was most pronounced in the fro ntal and temporal neocortex. The most significant correlations between AI a nd age decade were found in the prefrontal (R=0.35, P=0.001) and superior t emporal neocortex (R=0.43, P <0.001). Women had significantly higher uptake in the right parietal cortex (P <0.001), while men showed higher uptake in the cerebellum and the left anterior temporal and orbitofrontal cortex (al l P <0.01). This normative dataset allows age- and gender-specific patient and group assessment of Tc-99m-ECD per fusion SPET under a wide variety of clinical circumstances in relation to normal variations and highlights the importance of both age- and gender-specific normal datasets for optimal ana lysis sensitivity.