Purpose or Case Report: To present a MRI technic to explore the fetal petrous bone (3D high resolution MRI) and choanae, olfactory bulbs and sulci (3D whole brain sequence). To present the clinical applications in fetal detection of CHARGE syndrome. To remind the major diagnostic criteria of CHARGE syndrome.
Methods & Materials: In 2012-2013, 97 fetuses between 27 and 37 weeks of gestation were prospectively explored after maternal informed consent, in addition to the usual brain exploration, with a 3D high resolution T2 sequence with 1.4 mm scans centered on the petrous bones, and a 3D T2 TRUFISP sequence with 1.5 mm scans on the whole brain.
The cochlea, vestibule, semicircular canals, choanae, olfactory bulbs and sulci were analyzed.
These anatomical structures, as well as ocular globes, vermis and thymus were studied in 4 fetuses with US suspected CHARGE syndrome.
Results: The cochlea, anterior and lateral semicircular canals were identified in 95.8% of cases. In 4 cases motion artefacts prevented from a good analysis. Olfactory bulbs and sulci were correctly visualized in 94%. Choanae were always visible.
4 fetuses were referred for suspicion of CHARGE syndrome. The US abnormality were a cardiac malformation (3), external ears abnormalities (2), labiopalatine cleft (1), thymic hypoplasia (1).
MRI was performed at 26 to 32 weeks of gestation and showed
3 colobomas
4 absent semicircular canals
3 absent olfactory bulbs and sulci
1 bilateral choanal atresia
2 vermis hypoplasia
2 thymic hypoplasia
CHARGE syndrome was confirmed in all cases. 2 pregnancies were interrupted. 1 baby survived 8 weeks. 1 is 23 months old with multiple impairments.
Conclusions: Antenatal diagnosis of CHARGE syndrome is challenging because of the poor specificity of minor criteria (cardiac, limb, genital, oesophagal, urinary tract and central nervous system malformations, facial cleft) and the high difficulty to assess some of the major criteria: semicircular canal agenesis, arrhinencephalia, coloboma, choanal atresia. The 3D high resolution T2 TRUFISP MRI, as performed in our institution, provides a high sensitive tool to image these anatomical structures and thereby assess the diagnosis. Thymic and vermis hypoplasia are minor criteria that should lead to a petrous bone MRI exploration.
Given the severity of the malformations association in CHARGE syndrome, prenatal diagnostic is useful to help parents counselling and/or interrupt the pregnancy.