Feasibility of dynamic MRI for evaluating velopharyngeal insufficiency in children.

OBJECTIVE: To demonstrate the feasibility of dynamic MRI with near-real-time temporal resolution for analysing velopharyngeal closure. METHODS: Eleven children and young adults (seven girls, four boys, mean age: 8.4 years) with suspected velopharyngeal insufficiency (VPI), and one healthy volunteer underwent MRI (1.5 Tesla) using T2 fast imaging sequences. Imaging was done without any sedation at rest and during various phonations in the axial and sagittal planes. Images were analysed by two radiologists, a plastic surgeon and a speech therapist. RESULTS: The MRI examinations were well tolerated by even the youngest patient. A qualitative analysis found that the sagittal dynamic sequences during phonation were in relation to the clinical data in all patients. A quantitative analysis enabled calculation of the elevation angle of the soft palate in relation to the hard palate, the velar eminence angle and the percentage of reduction of the antero-posterior diameter of the pharyngeal lumen. CONCLUSION: Dynamic MRI is a non-invasive, rapid and repeatable method. It can be considered a complementary tool to endoscopy and fluoroscopy, particularly in children, for assessing VPI without any sedation or radiation exposure.

Pineal cysts in children.

OBJECTIVE: To describe the prevalence and characteristics of pineal cysts found on MRI in children. METHODS: This is a retrospective monocentric study of all brain magnetic resonance imaging (MRI) examinations performed under the same technical conditions for checking the idiopathic nature of short stature (ISS group, n = 116) and for the investigation of central precocious puberty (CPP) over a 3-year period (n = 56). Dimensions, wall and septal thickness, number of locules, signal intensity, and the presence of a solid component were analysed. Ten of 19 cysts were re-evaluated (follow-up interval 4-28 months). The prevalence of the pineal cysts was compared between the two groups using χ2 and Fisher's exact tests, and a significance threshold of p < 0.05. RESULTS: The prevalence of cysts was comparable in the two groups, CPP (10.7%) and ISS (11.2%). Cyst characteristics were similar in the two groups and 74% had thin septations. None of the cysts changed on follow-up. None of the children with pineal cysts exhibited neurological signs. CONCLUSION: Benign pineal cysts are a common finding in young children. High-resolution MRI demonstrates that these cysts are often septated. This pattern is a normal variant and does not require follow-up MR imaging or IV contrast media.

[Fetal cerebral magnetic resonance imaging (MRI). Indications, normal and pathological patterns]. / Imagerie par résonance magnétique (IRM) foetale cérébrale : indications, aspects normaux et pathologiques.

Fetal MRI is a specific imaging modality, always performed after a reference ultrasound examination. The decision to perform an MRI-scan must take into account the anxiety constantly generated by the need for this unusual examination during pregnancy. To date, no side-effect associated with 1.5 tesla magnets has been described. Compared to ultrasonography, fetal brain MRI provides better contrast between grey and white matter, as well as better delineation of the brainstem (pontic curvature) and the cerebellum (lobules and fissures). However, it often remains difficult to inform parents about prognosis. Thereby, it is of utmost importance to be familiar with the definite criteria associated with a poor neurological prognosis such as lack of pontic curvature or as diffuse or bilateral cortical malformations. This has to be considered within the framework of French regulations which allow pregnancy termination with no time limit. The optimal timing to perform a fetal MRI-scan depends on the context. The period between 27 and 30 weeks of gestation is a good balance between gestational age and gyration or sulcation development. The main ultrasonographic findings requiring MRI are ventriculomegalies and posterior fossa abnormalities. MRI exploration can sometimes be performed despite a normal ultrasonography in case of genetic disorders such as tuberous sclerosis and lissencephalies. In addition to its diagnostic value towards decision to terminate pregnancy, fetal MRI can be used as "in vivo autopsy", in case of expected technical difficulties or refusal of post-abortion examinations by relatives. Technical advances (real time and specific sequences like diffusion tensor and spectroscopy) and prospective clinical studies will probably improve the efficiency of this method to assess neurological prognosis.