IMR Press / CEOG / Volume 48 / Issue 4 / DOI: 10.31083/j.ceog4804158
Open Access Case Report
The brainstem-tentorium angle revisited. Difficulties encountered and possible solutions
Laura Joigneau1,2Yolanda Ruiz1,2,3Coral Bravo2,3Julia Bujan4,5,6Miguel A Ortega4,5,6,7,*,†Juan De León-Luis1,2,3,8,†
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1 Department of Radiology. University Hospital Gregorio Marañón. 28009 Madrid, Spain
2 Fetal Medicine Unit, Maternal and Child Health and Development Network, Department of Obstetrics and Gynecology, Gregorio Marañón Hospital, 28009 Madrid, Spain
3 Department of Obstetrics and Gynecology, Complutense University of Madrid, 28009 Madrid, Spain
4 Ramón y Cajal Institute of Healthcare Research (IRYCIS), 28034 Madrid, Spain
5 Department of Medicine and Medical Specialties, Faculty of Medicine and Health Sciences, University of Alcalá, Alcalá de Henares, 2880 Madrid, Spain
6 University Center for the Defense of Madrid (CUD-ACD), 28047 Madrid, Spain
7 Department of Cancer Registry and Pathology, Hospital Universitario Principe de Asturias, Alcalá de Henares, 28801 Madrid, Spain
8 Department of Public and Maternal and Child Health, School of Medicine, Complutense University of Madrid, 28801 Madrid, Spain
*Correspondence: (Miguel A Ortega)
These authors contributed equally.
Clin. Exp. Obstet. Gynecol. 2021, 48(4), 991–994;
Submitted: 22 November 2020 | Revised: 11 January 2021 | Accepted: 19 January 2021 | Published: 15 August 2021
Copyright: © 2021 The Author(s). Published by IMR Press.
This is an open access article under the CC BY 4.0 license (

Background: Fetal posterior fossa fluid collections (PFFC) can range from normal variants to severe anomalies with highly variable neurological prognosis. The diagnosis of these entities is still a challenge for ultrasound as well as for fetal magnetic resonance imaging (MRI). The measurements of the brainstem-vermis angle (BV angle) and the brainstem-tentorium angle (BT angle) have been described as helpful in the differential diagnosis of the PFFC. Case: We present a case with posterior fossa abnormalities where the measurement of the BT angle could be difficult due to the anatomy distortion. Conclusion: We propose two alternative ways of measuring the BT angle that could be reliable in all the spectrum of PFFC.

Fetal posterior fossa fluid collections
Fetal magnetic resonance imaging
Brainstem-tentorium angle
BT angle
Brainstem-vermis angle
FIS-PI18/00912/Instituto de Salud Carlos III (Plan Estatal de I + D + i 2013-2016)
FIS-PI13/02769/Instituto de Salud Carlos III (Plan Estatal de I + D + i 2013-2016)
BA#09/90011/Instituto de Salud Carlos III (Plan Estatal de I + D + i 2013-2016)
B2017/BMD-3804 MITIC-CM/European Development Regional Fund “A way to achieve Europe” (ERDF)
Fig. 1.
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