Prenatal US evaluation of the spinal cord using high-frequency linear transducers.

We illustrate the contribution of high-frequency linear abdominal transducers in the prenatal US examination of the spinal cord. After birth, such transducers are commonly used in US examination of the spinal cord. During the third trimester of gestation, the fetal spine is commonly facing anteriorly and US images of the spinal cord can be acquired using a high-frequency linear abdominal transducer. Images of the normal spinal cord, normal variants (ventriculus terminalis, cyst of filum terminale) and spinal cord abnormalities (myelomeningocele, meningocele, diastematomyelia, tethered spinal cord and caudal regression syndrome) are presented. In this pictorial essay, comparison between images acquired with low- and high-frequency transducers are provided as well as correlation with postnatal data. In the normal spine, anatomical details such as the conus medullaris, the filum terminale and the nerve root bundles are exquisitely depicted, making it possible to differentiate normal variants from abnormalities. In abnormal cases, the position of the conus medullaris, its shape and the nerve roots can be analyzed in detail. We describe the benefits of using high-frequency linear transducers in US examination of the spinal cord, which is common after birth but has not been hitherto reported in fetuses.

Prenatal evaluation of the middle ear and diagnosis of middle ear hypoplasia using MRI.

BACKGROUND: Analysis of the middle ear with fetal MRI has not been previously reported. OBJECTIVE: To show the contribution of fetal MRI to middle ear imaging. MATERIALS AND METHODS: The tympanic cavity was evaluated in 108 fetal cerebral MRI examinations (facial and/or cerebral malformation excluded) and in two cases, one of Treacher Collins syndrome (case 1) and the other of oculo-auriculo-vertebral (OUV) spectrum (case 2) with middle ear hypoplasia identified by MRI at 27 and 36 weeks' gestation, respectively. RESULTS: In all 108 fetuses (mean gestational age 32.5 weeks), the tympanic cavity and T2 hypointensity related to the ossicles were well visualised on both sides. Case 1 had micro/retrognathia and bilateral external ear deformity and case 2 had retrognathism with a left low-set and deformed ear. MRI made it possible to recognize the marked hypoplasia of the tympanic cavity, which was bilateral in case 1 and unilateral in case 2. Both syndromes are characterized by craniofacial abnormalities including middle ear hypoplasia, which cannot be diagnosed with US. CONCLUSION: The middle ear cavity can be visualized with fetal MRI. We emphasize the use of this imaging modality in the diagnosis of middle ear hypoplasia.