CORRELATION OF FETAL FRONTAL-LOBE AND TRANSCEREBELLAR DIAMETER MEASUREMENTS - THE UTILITY OF A NEW PRENATAL SONOGRAPHIC TECHNIQUE

Several authors have reported the value of the sonographic assessment of both the fetal frontal lobe and the cerebellum. Both frontal lobe s hortening and cerebellar hypoplasia have been associated with fetal an euploidy. We anecdotally observed that the distance between the calvar ium and the posterior cavum septum pellucidum (frontal lobe) closely a pproximated the transcerebellar diameter. This study was undertaken to investigate this relationship. Between 1 July 1994 and 1 January 1996 , the frontal lobe (posterior cavum septum pellucidum to the inner cal varium) and transcerebellar diameter were measured in patients referre d to two prenatal ultrasound laboratories in Denver, Colorado, USA. Al l pregnancies had certain dates and were uncomplicated. Statistical co mparison was completed using interval polynomial regression analysis. During the study period we performed 221 detailed ultrasound examinati ons in which the frontal lobe and the transcerebellar diameter were me asured. We found a correlation coefficient of 0.950 when comparing the two variables (p < 0.0001). Some conditions (Down's syndrome, lethal trisomies and pathological microcephaly) have differential effects on the frontal lobe and the transcerebellar diameter. Our preliminary jud gement is that this new technique may prove to be a useful tool in ass essing the relative effect of these conditions on structural neuroanat omy.