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The diagnosis of hemimegalencephaly using in utero MRI
1Department of Neuroradiology, Royal Hallamshire Hospital, Sheffield, UK.
Aim:
To review our experience of diagnosing hemimegalencephaly (HME) using in utero magnetic resonance imaging (MRI).
Materials And Methods:
The MRI database in the Academic Unit of Radiology, University of Sheffield was searched using "hemimegalencephaly" and "in utero MR" as search terms. The antenatal histories and reports of ultrasound imaging were reviewed as well as the in utero MRI images.
Results:
Nine cases of foetal HME were located. One case was referred after ultrasound with the diagnosis of HME, one as a "complex brain malformation", and one as a "mass lesion". The other six were referred as "unilateral ventriculomegaly". A common finding in foetuses imaged in the second trimester was disruption of the normal "transient structures" found in the developing cerebral hemispheres.
Conclusion:
HME is a difficult diagnosis to make using antenatal ultrasound and in utero MRI should be considered in cases of unilateral ventriculomegaly diagnosed at ultrasound. Disruption of the transient structures of the cerebral hemispheres is a common finding on in utero MRI and can sometimes produce mass-like appearances in the region of the germinal matrix/ganglionic eminence.
Insights
Diagnosing fetal hemimegalencephaly (HME) is challenging with ultrasound alone. In utero magnetic resonance imaging (MRI) aids diagnosis, especially when unilateral ventriculomegaly is detected.
Area of Science:
- Neuroimaging
- Fetal Medicine
- Developmental Biology
Background:
- Hemimegalencephaly (HME) is a rare congenital brain malformation.
- Antenatal diagnosis of HME can be challenging with conventional ultrasound.
- In utero magnetic resonance imaging (MRI) offers advanced visualization of fetal brain development.
Purpose of the Study:
- To evaluate the diagnostic utility of in utero MRI for hemimegalencephaly (HME).
- To review experience with diagnosing HME using prenatal MRI.
- To identify key imaging findings suggestive of HME on fetal MRI.
Main Methods:
- Retrospective review of fetal MRI cases diagnosed with HME.
- Search of MRI database using specific keywords: "hemimegalencephaly" and "in utero MR".
- Analysis of antenatal histories, ultrasound reports, and in utero MRI images.
Main Results:
- Nine cases of fetal HME were identified.
- Referral indications included HME, complex brain malformation, mass lesion, and unilateral ventriculomegaly.
- Disruption of transient cerebral hemisphere structures was a common second-trimester finding.
Conclusions:
- In utero MRI is valuable for diagnosing HME, particularly when antenatal ultrasound suggests unilateral ventriculomegaly.
- Disruption of transient cerebral hemisphere structures on fetal MRI can mimic mass lesions.
- Prenatal MRI enhances the diagnostic accuracy of complex fetal brain malformations.
