Diffusion Tensor MR Imaging Visualizes the Altered Hemispheric Fiber Connection in Callosal Dysgenesis
Seung-Koo Leea,
Susumu Morib,
Dong Joon Kima,
Sei Young Kima,
Si Yeon Kima and
Dong Ik Kima
a Department of Diagnostic Radiology and Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea
b Department of Radiology and Kennedy Krieger Institute, F. M. Kirby Research Center for Functional Brain Imaging, Johns Hopkins University School of Medicine, Baltimore, MD
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FIG 1. Anatomic T2-weighted images, diffusion tensor-based color maps, FA maps, and FT of callosal dysgenesis. Upper row depicts normal findings of corpus callosum; i.e., clear red fibers and high FA bundles crossing midline at diffusion tensor MR imaging. Tractography shows interhemispheric fiber connections through corpus callosum; i.e., red-colored fibers in the midline. Middle row shows partially developed corpus callosum in genu portion (white arrow). Tractography demonstrates fibers from parieto-occipital regions converging into small red-colored genu as well as fibers from frontal lobes. Fibers from the posterior part run anteriorly and form longitudinal green-colored fibers, the Probst bundle. In complete agenesis of corpus callosum, the Probst bundle is more apparent as thick, green, high-FA fibers medial to lateral ventricle (double arrows). Tractography shows thick bundles of green color consist of various fibers from ipsilateral hemisphere, Probst bundle, and thick red-colored AC (black arrows).
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FIG 2. T2-weighted and diffusion tensor-based color images at the level of the AC. Right-to-left running red fibers are identified in control subject and one patient with callosal agenesis, whereas other patients did not show these transverse fascicles on diffusion tensor maps (white arrows).
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