Interuncal distance as a measure of hippocampal atrophy: normative data on axial MR imaging.

PURPOSE To assess the effects of age and gender on the interuncal distance measured from MR images.

METHODS High-field strength MR images (axial) of 75 volunteers, 21-82 years old and free of neurologic disorders, were used to measure the interuncal distance.

RESULTS The interuncal distance increased with age (r = 0.66, P < .0001). The mean (SD) interuncal distance for all subjects was 21.4 (4) mm with a range of 12 to 29 mm.

CONCLUSIONS The interuncal distance in healthy subjects is unlikely to exceed 30 mm. Our data may be of clinical significance in view of a previous report stating that the interuncal distance may be enlarged in pathologic hippocampal degeneration, such as in patients with Alzheimer disease.