Diagnostic value and clinical problems of MR imaging in congenital anomalies of the central nervous system, 1

Various forms of cerebral dysgenesis were studied by means of MR Imaging (MRI) in order to determine the diagnostic efficacy of MRI in comparison with conventional diagnostic procedures. All subjects have been diagnosed during the last 16 months at the National Kagawa Children's Hospital with conventional methods and then referred to MRI study at the Shinsuma Hospital, where a MRI system of a regular-conducting magnet operating at a field strength of 1.5 KG (Picker International Corp., U.S.A.) has been installed. Using the two-dimensional Fourier transform technique, three radiofrequency pulse sequences; inversion recovery: IR 2100/500, and spin-echo: SE 2100/40 or 2100/80, were routinely applied. Compared with X-ray CT, MR proved to be advantageous in the more precise detection of the pathoanatomical relation and in providing information about the myelinating process. The analysis of the myelinating process by MRI in such cerebral dysgeneses as lissencephaly, frontal-lobe dysgenesis, agenesis of the corpus callosum, and microcephalic hydrocephalus was very important for the detection of further functional cerebral developments. The pathoanatomical analysis by MRI, in particular with the midline sagittal view, is extremely advantageous in the diagnosis of Chiari malformation, holoprosencephaly, the Dandy-Walker syndrome, congenital dermal sinus, syringobulbia, and others. The disadvantages or weak points of MRI were also identified in this study. The CSF dynamics in both the major and minor fluid pathways as analyzed by metrizamide CT cisternography or ventriculography is much superior to the information revealed by MRI, although the SE technique can demonstrate some fluid distribution in the brain parenchyma and a different signal intensity in the fluid movements. The information about the bony structure in dysraphic states and calcifications in associated anomalies was also poor. (J.P.N.)