Magnetic Resonance Imaging of Corpus Callosum Dysgenesis
The normal corpus callosum is probably best viewed in the midline sagittal section (Figure 1). This plane can be achieved by neuropathologists at brain cutting or, noninvasively, by Magnetic Resonance Imaging (abbreviated MRI or simply MR). By comparison, using Computed Tomography (CT) it is generally physically impossible to produce direct midsagittal images. Ultrasound, another commonly used imaging modality, can image patients in the midsagittal plane but requires a sonographic “window” through the skull. This is only available naturally in infants with fontanels which are still open. MR, on the other hand, allows high resolution and high contrast images in multiple directly acquired planes in patients of all ages. For this reason, MR is by far the most superior tool currently available for evaluation of the corpus callosum in its normal and pathologic state. While it is true that neuropathologists are able to obtain very high resolution images of the brain, such studies are not available until after the patient’s demise. Obviously at that time it is too late to administer neuropsychological tests to these patients to investigate their callosal function. As will be seen, MR not only allows the identification of abnormal development of the corpus callosum in the living patient, but allows accurate delineation of the extent of callosal abnormality as well. Another advantage over neuropathology is that MR can perform direct acquisitions in the axial, coronal, and sagittal planes. Once the neuropathologist has made the standard cuts in the axial (or coronal) plane, it is often difficult to piece the brain back together to produce precise sagittal images in the case of an incidental finding such as callosal dysgenesis.
KeywordsCorpus Callosum Anterior Commissure Midsagittal Plane High Contrast Image Callosal Agenesis
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