PURPOSE: To establish that incorrect scanning of the fetal posterior fossa may falsely create the appearance of a mega-cisterna magna (MCM) or Dandy-Walker variant (DWV). MATERIALS AND METHODS: After routine sonography, 100 consecutive fetuses (gestational age range, 25-40 weeks) without abnormality underwent additional posterior fossa scanning in an attempt to create the appearance of an MCM (anteroposterior diameter larger than 10 mm) or DWV. Sonograms were obtained in a plane inferior to or angled more coronally than the routine axial plane. RESULTS: The posterior fossa was depicted in 93 fetuses. Pseudo-MCM occurred in 35 (38%) of 93 fetuses: 12 (30%) of 40 fetuses aged 25.0-29.9 weeks, 11 (50%) of 22 fetuses aged 30.0-34.9 weeks, and 12 (39%) of 31 fetuses aged 35.0-40.0 weeks. Pseudo-DWV occurred in 40 (43%) of 93 fetuses: 20 (50%) of 40 fetuses aged 25.0-29.9 weeks, 12 (55%) of 22 fetuses aged 30.0-34.9 weeks, and eight (26%) of 31 fetuses aged 35.0-40.0 weeks. CONCLUSION: Sonography of the posterior fossa in an angled semi-coronal plane should be avoided because it may create an appearance that mimics an abnormality.
PURPOSE: To establish that incorrect scanning of the fetal posterior fossa may falsely create the appearance of a mega-cisterna magna (MCM) or Dandy-Walker variant (DWV). MATERIALS AND METHODS: After routine sonography, 100 consecutive fetuses (gestational age range, 25-40 weeks) without abnormality underwent additional posterior fossa scanning in an attempt to create the appearance of an MCM (anteroposterior diameter larger than 10 mm) or DWV. Sonograms were obtained in a plane inferior to or angled more coronally than the routine axial plane. RESULTS: The posterior fossa was depicted in 93 fetuses. Pseudo-MCM occurred in 35 (38%) of 93 fetuses: 12 (30%) of 40 fetuses aged 25.0-29.9 weeks, 11 (50%) of 22 fetuses aged 30.0-34.9 weeks, and 12 (39%) of 31 fetuses aged 35.0-40.0 weeks. Pseudo-DWV occurred in 40 (43%) of 93 fetuses: 20 (50%) of 40 fetuses aged 25.0-29.9 weeks, 12 (55%) of 22 fetuses aged 30.0-34.9 weeks, and eight (26%) of 31 fetuses aged 35.0-40.0 weeks. CONCLUSION: Sonography of the posterior fossa in an angled semi-coronal plane should be avoided because it may create an appearance that mimics an abnormality.
Authors: E M Simon; R B Goldstein; F V Coakley; R A Filly; K C Broderick; T J Musci; A J Barkovich Journal: AJNR Am J Neuroradiol Date: 2000-10 Impact factor: 3.825
Authors: Catherine Limperopoulos; Richard L Robertson; Judy A Estroff; Carol Barnewolt; Deborah Levine; Haim Bassan; Adré J du Plessis Journal: Am J Obstet Gynecol Date: 2006-04 Impact factor: 8.661
Authors: Catherine Limperopoulos; Richard L Robertson; Omar S Khwaja; Caroline D Robson; Judy A Estroff; Carole Barnewolt; Deborah Levine; Donna Morash; Luanne Nemes; Linda Zaccagnini; Adré J du Plessis Journal: AJR Am J Roentgenol Date: 2008-06 Impact factor: 3.959