title: Measurement of middle cerebral artery diameter as a method for assessment of brain sparing in intra-uterine growth-restricted discordant twins.
abstract: OBJECTIVE
  Blood vessel resistance is assessed by flow velocity indexes. However, the actual resistance should be more strongly correlated with vessel diameter rather than variations in flow velocity. We aimed to determine the utility of middle cerebral artery (MCA) diameter measurement as a tool for evaluating brain sparing effect in intrauterine growth-restricted (IUGR) discordant twins.
  
  
  METHODS
  Ten dichorionic-diamniotic twin pairs with weight discordance were included in the study. Fetal assessment included estimated fetal weight, umbilical artery flow, MCA flow and MCA diameter. Paired statistical analysis was used to compare MCA diameter and MCA pulsatility index (PI) between the discordant twins.
  
  
  RESULTS
  MCA diameter was significantly larger in the smaller twin (mean diameter 3.55 ± 0.26 vs 2.71 ± 0.22, P = 0.018, mean ratio 1.39 ± 0.14). There was no significant difference in MCA PI values within the twin pairs (mean PI 1.51 ± 0.13 vs 1.57 ± 0.07, P = 0.878, mean ratio 0.99 ± 0.11).
  
  
  CONCLUSIONS
  Measurement of MCA diameter can potentially be used as a tool for assessing vessel resistance. Further studies are needed to assess the feasibility and sensitivity of this method as well as the clinical significance of MCA dilatation in the presence of normal Doppler flow indexes.
authors.affiliation: Department of Obstetrics and Gynecology, Sheba Medical Center, Tel-Hashomer, Ramat-Gan, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Eran
authors.initials: E
authors.lastname: Barzilay
authors.forename: Jigal
authors.initials: J
authors.lastname: Haas
authors.forename: Hila
authors.initials: H
authors.lastname: de Castro
authors.forename: Yoav
authors.initials: Y
authors.lastname: Yinon
authors.forename: Reuven
authors.initials: R
authors.lastname: Achiron
authors.forename: Yinon
authors.initials: Y
authors.lastname: Gilboa
mesh_terms: D005260:Female; D005317:Fetal Growth Retardation / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging*; D011247:Pregnancy; D059285:Pregnancy, Twin; D014430:Twins, Monozygotic; D016216:Ultrasonography, Prenatal; D014655:Vascular Resistance