To evaluate the distribution of normal intracranial artery diameter according to sex and age, using three-dimensional reconstruction rotational angiography.

One hundred and twenty-five adults with normal intracranial arteries who underwent 3D rotational angiography (n=177) were included in this study. The arterial diameter was measured at four sites of the internal carotid artery (cavernous, paraophthalmic, supraclinoid, and distal), that of the middle cerebral artery at two (proximal and distal), and that of the anterior cerebral artery at one (middle). For each sex and age group (<30, 30-39, 40-49, 50-59, > or = 60 years), the mean diameter of the artery at these seven sites was calculated, and differences analysed. In addition, the middle cerebral artery diameter was compared between a younger group (<50 years) and an older group (> or = 50 years).

The mean diameter at each site for each sex was as follows: male (mean±SD): 4.61±0.69, 3.96± 0.60, 3.48±0.45, 3.61±0.50, 2.44±0.32, 2.44±0.37, 1.81±0.32; female: 4.29±0.57, 3.83±0.56, 3.37±0.56, 3.52±0.48, 2.32±0.37, 2.30±0.36, 1.76±0.34. For those in their 40s, the diameter at five sites (all four sites of the internal cerebral artery and a distal middle cerebral artery) was significantly greater in males than in females. For other age groups, however, the difference between the sexes was absent, or was significant at only one (cavernous internal cerebral artery for those in their 30s) or two (proximal and distal middle cerebral artery for those in their 50s) of the seven sites. In the older age group, the diameter of the proximal middle cerbral artery was 2.59±0.35 mm in males and 2.38±0.37 mm in females. For the distal middle cerebral artery, the corresponding figures were 2.63±0.43 and 2.39±0.35 mm, respectively. For both sexes, the differences between the two age groups were significant.

For those in their 40s, the normal diameter of the intracranial artery at most arterial sites was significantly greater in males than in females. The normal diameter of the middle cerebral artery was significantly greater or tended to be greater among the older group than the younger group (for males and females, respectively, 2.59±0.35 mm and 2.38±0.37 mm at the proxinal site, and 2.63±0.43 mm and 2.39±0.35 mm at the distal site).