Purpose: To test the assumption underlying every morphometric twin study that the brains of monozygotic twins are almost identical.
Methods: High resolution MRI of the neurocranium of 26 monozygotic twin pairs were acquired and the volumes of 36 cerebral structures were measured. The same twins served as control group after rear-ranging them into non-related pairs of same sex and matching them for age, body height and body weight.
Results: For most of the examined structures the correlations within the twins were significant (R = 0.97-0.59). Except for total forebrain volume the controls showed no significant similarity.
Conclusions: For almost every measured cerebral structure the assumption, that significant similarities exist between healthy monozygotic twins is correct. Therefore discordant monozygotic twins represent an excellent sample when investigating cerebral correlates of neurologic and psychiatric disorders.