How accurately does current fetal imaging identify posterior fossa anomalies?
OBJECTIVE
The first objective of our study was to describe the prevalence and spectrum of posterior fossa anomalies over 5 years in a major fetal care center where the referral diagnosis (by fetal sonography) was investigated by fetal MRI and, if confirmed, by postnatal MRI if possible. The second objective was to assess the accuracy with which fetal MRI predicts postnatal MRI findings in this population.


METHODS
We retrospectively identified all cases of suspected fetal posterior fossa anomalies referred to our center from 2002 through 2006. We reviewed maternal, fetal, neonatal, and follow-up records of all cases and fetal and early postnatal imaging studies.


RESULTS
Of the 90 cases of suspected fetal posterior fossa anomalies (by fetal sonography) referred over the study period, 60 (67%) were confirmed by fetal MRI. Of 42 live-born infants, 39 (93%) underwent postnatal MRI. There was complete agreement in fetal and postnatal MRI diagnoses in 23 infants (59%). In 16 cases (41%), fetal and postnatal MRI diagnoses disagreed; postnatal MRI excluded fetal MRI diagnoses in six cases (15%) and revealed additional anomalies in 10 cases (26%).


CONCLUSIONS
Although a valuable adjunct to fetal sonography in cases of suspected posterior fossa anomaly, current fetal MRI, particularly in early gestation, has limitations in accurately predicting postnatal MRI abnormalities. Advancing the accuracy of MRI for the diagnosis of posterior fossa anomalies will require greater understanding of normal brain development and improved tissue resolution of fetal MRI. During the interim, our findings strongly support the need for postnatal MRI follow-up in cases with suspected posterior fossa anomalies by fetal MRI.
Limperopoulos
Catherine
C
Fetal-Neonatal Neurology Research Program, Department of Neurology, Children's Hospital Boston and Harvard Medical School, Boston, MA, USA. catherine.limperopoulos@mcgill.ca
Robertson
Richard L
RL
Khwaja
Omar S
OS
Robson
Caroline D
CD
Estroff
Judy A
JA
Barnewolt
Carole
C
Levine
Deborah
D
Morash
Donna
D
Nemes
Luanne
L
Zaccagnini
Linda
L
du Plessis
Adré J
AJ
D001900:Boston / Q000453:epidemiology; D003388:Cranial Fossa, Posterior / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000473:pathology*; D019465:Craniofacial Abnormalities / Q000175:diagnosis* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D011379:Prognosis; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000706:statistics & numerical data*