title: Vermian biometric parameters in the normal and abnormal fetal posterior fossa: three-dimensional sonographic study.
abstract: OBJECTIVE
  The purposes of this study were to describe a 3-dimensional sonographic technique for evaluation of the fetal vermis and to compare vermian biometric parameters in fetuses with a normal and an abnormal posterior fossa.
  
  
  METHODS
  A prospective study was conducted from 2006 through 2008 on 12 fetuses with an abnormal posterior fossa and 73 healthy control fetuses from 18 to 35 weeks' gestation. Three-dimensional scans of the fetal head were performed in the axial plane, using static volume contrast imaging in the C-plane. The vermian perimeter, cross-sectional area, and superoinferior diameter were measured and compared between abnormal and normal fetuses using the Wilcoxon nonparametric test. Linear regression analysis was used to describe trends of the vermis during gestation. The z scores for perimeter, cross-sectional area, and superoinferior diameter measurements in the abnormal posterior fossa group in each 2-week interval were calculated.
  
  
  RESULTS
  Twelve fetuses with an abnormal posterior fossa were recruited: 3 with a Blake pouch cyst, 1 vermian cyst, 1 enlarged cisterna magna, 2 Dandy-Walker malformation, 4 partial vermian agenesis, and 1 hemicerebellar hypoplasia. The vermian cross-sectional area was reduced significantly in the fetuses with an abnormal posterior fossa compared with the control fetuses starting at 18 to 19 weeks' gestation (P = .01); the mean vermian superoinferior diameter was lower only from 22 to 23 weeks (P = .01); and the mean vermian perimeter was decreased from 28-29 weeks' gestation (P = .03). Linear regression analysis of the parameters showed that fetuses with an abnormal posterior fossa had a statistically significantly lower growth rate than control fetuses during gestation (P < .001).
  
  
  CONCLUSIONS
  Measurements of the cross-sectional area were more useful than those of the perimeter and superoinferior diameter in distinguishing between fetuses with a normal and an abnormal posterior fossa during the early stages of gestation.
authors.affiliation: Prenatal Medicine Unit, Department of Obstetrics and Gynecology, Modena Hospital, Modena and Reggio Emilia University, Largo del Pozzo 71, 41123 Modena, Italy. emmabertucci@libero.it
authors.forename: Emma
authors.initials: E
authors.lastname: Bertucci
authors.forename: Liat
authors.initials: L
authors.lastname: Gindes
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Mazza
authors.forename: Claudia
authors.initials: C
authors.lastname: Re
authors.forename: Liat
authors.initials: L
authors.lastname: Lerner-Geva
authors.forename: Reuven
authors.initials: R
authors.lastname: Achiron
mesh_terms: D016022:Case-Control Studies; D002531:Cerebellum / Q000002:abnormalities / Q000000981:diagnostic imaging*; D003388:Cranial Fossa, Posterior / Q000002:abnormalities / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D007231:Infant, Newborn; D016014:Linear Models; D011247:Pregnancy; D011256:Pregnancy Outcome; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D016216:Ultrasonography, Prenatal / Q000379:methods*