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Normal Fetal Posterior Fossa in MR Imaging: New Biometric Data and Possible Clinical Significance

Normal Fetal Posterior Fossa in MR Imaging: New Biometric Data and Possible Clinical Significance BACKGROUND AND PURPOSE: Posterior fossa malformations are a common finding in prenatal diagnosis. The objectives of this study are to re-evaluate existing normal MR imaging biometric data of the fetal posterior fossa, suggest and evaluate new parameters, and demonstrate the possible clinical applications of these data. MATERIALS AND METHODS: This was a retrospective review of 215 fetal MR imaging examinations with normal findings and 5 examinations of fetuses with a suspected pathologic posterior fossa. Six previously reported parameters and 8 new parameters were measured. Three new parameter ratios were calculated. Interobserver agreement was calculated by using the intraclass correlation coefficient. RESULTS: For measuring each structure, 151–211 MR imaging examinations were selected, resulting in a normal biometry curve according to gestational age for each parameter. Analysis of the ratio parameters showed that vermian lobe ratio and cerebellar hemisphere ratio remain constant with gestational age and that the vermis-to-cisterna magna ratio varies with gestational age. Measurements of the 5 pathologic fetuses are presented on the normal curves. Interobserver agreement was excellent, with the intraclass correlation coefficients of most parameters above 0.9 and only 2 parameters below 0.8. CONCLUSIONS: The biometry curves derived from new and existing biometric data and presented in this study may expand and deepen the biometry we use today, while keeping it simple and repeatable. By applying these extensive biometric data on suspected abnormal cases, diagnoses may be confirmed, better classified, or completely altered. ABBREVIATIONS: ICC intraclass correlation coefficient CHR cerebellar hemisphere ratio CMS cisterna magna cross-sectional area PF posterior fossa TCD transcerebellar diameter VCMR vermis-to-cisterna magna ratio VLR vermian lobe ratio VP vermian perimeter VS vermian cross-sectional area http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png American Journal of Neuroradiology American Journal of Neuroradiology

Normal Fetal Posterior Fossa in MR Imaging: New Biometric Data and Possible Clinical Significance

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References (34)

Publisher
American Journal of Neuroradiology
Copyright
Copyright © 2015 by the American Society of Neuroradiology.
ISSN
0195-6108
eISSN
1936-959X
DOI
10.3174/ajnr.A4258
pmid
25655869
Publisher site
See Article on Publisher Site

Abstract

BACKGROUND AND PURPOSE: Posterior fossa malformations are a common finding in prenatal diagnosis. The objectives of this study are to re-evaluate existing normal MR imaging biometric data of the fetal posterior fossa, suggest and evaluate new parameters, and demonstrate the possible clinical applications of these data. MATERIALS AND METHODS: This was a retrospective review of 215 fetal MR imaging examinations with normal findings and 5 examinations of fetuses with a suspected pathologic posterior fossa. Six previously reported parameters and 8 new parameters were measured. Three new parameter ratios were calculated. Interobserver agreement was calculated by using the intraclass correlation coefficient. RESULTS: For measuring each structure, 151–211 MR imaging examinations were selected, resulting in a normal biometry curve according to gestational age for each parameter. Analysis of the ratio parameters showed that vermian lobe ratio and cerebellar hemisphere ratio remain constant with gestational age and that the vermis-to-cisterna magna ratio varies with gestational age. Measurements of the 5 pathologic fetuses are presented on the normal curves. Interobserver agreement was excellent, with the intraclass correlation coefficients of most parameters above 0.9 and only 2 parameters below 0.8. CONCLUSIONS: The biometry curves derived from new and existing biometric data and presented in this study may expand and deepen the biometry we use today, while keeping it simple and repeatable. By applying these extensive biometric data on suspected abnormal cases, diagnoses may be confirmed, better classified, or completely altered. ABBREVIATIONS: ICC intraclass correlation coefficient CHR cerebellar hemisphere ratio CMS cisterna magna cross-sectional area PF posterior fossa TCD transcerebellar diameter VCMR vermis-to-cisterna magna ratio VLR vermian lobe ratio VP vermian perimeter VS vermian cross-sectional area

Journal

American Journal of Neuroradiology – American Journal of Neuroradiology

Published: Apr 1, 2015

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