DEEP CALCARINE SULCUS AND PROMINENT CALCAR AVIS

MR imaging examinations of the brain 100 consecutive patients, ages ra nging from 1 year to 66 years, were evaluated in order to investigate the frequency of a deep calcarine sulcus and prominent calcar avis. Tw enty-four cases (24 %) were found with a deep calcarine sulcus and pro minent calcar avis. These were bilateral in four patients, and unilate ral in twenty. Fifteen of the unilateral cases demonstrated a right-si ded involvement, and remaining five were left-sided. A deep calcarine sulcus and prominent calcar avis should be distinguished from disorder s of neuronal migration and organization such as schizencephaly and he terotopia. Also, based on our findings in this study, we speculate tha t it is the deep calcarine sulcus and prominent calcar avis which crea tes the appearance of the so-called accessory occipital ventricle.