Effects of aging on regional cerebral blood flow assessed by using technetium Tc 99m hexamethylpropyleneamine oxime single-photon emission tomography with 3D stereotactic surface projection analysis.

OBJECTIVES Although many previous reports have described age-related changes in regional cerebral blood flow (rCBF), none has used 3D stereotactic surface projection (3D-SSP) analysis, which is able to detect subtle and significant changes in rCBF. METHODS The subjects were 31 healthy volunteers (16 men and 15 women; 50-79 years of age) without abnormal MR imaging and MR angiographic findings, cognitive impairment, or depression. For each subject, rCBF was evaluated by using technetium Tc 99m-radiolabeled hexamethylpropyleneamine oxime single-photon emission CT. Maps of rCBF were compared among different age groups (50-59, 60-69, and 70-79 years of age) by using 3D-SSP. The mean z score for each gyrus was calculated for each age group by using a recently developed stereotactic extraction estimation method. RESULTS Significant age-related reductions in rCBF were seen in the bilateral cingulate gyri, left inferior gyrus, bilateral medial frontal gyri, left subcallosal gyrus, and left superior temporal gyrus. Extensive and constant reduction in rCBF occurred with increasing age in the bilateral anterior cingulate gyri, and the mean z score for this region was the highest among all the regions examined. CONCLUSION The 3D-SSP analysis revealed that the greatest reduction in rCBF occurred within the bilateral anterior cingulate gyri in normal middle-aged and older subjects.