AJNR. American journal of neuroradiology
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AJNR Am J Neuroradiol · Nov 2009
Diffusion tensor imaging study of the cortical origin and course of the corticospinal tract in healthy children.
Several studies have questioned the traditional belief that the corticospinal tract (CST) arises exclusively from the precentral gyrus and passes through the anterior half of the posterior limb of the internal capsule (PLIC) in humans; however, no direct evidence existed from structural imaging, and developmental aspects of CST origin have not been clarified. We used diffusion tensor imaging (DTI) tractography to test the hypotheses that CST can originate from both pre- and postcentral gyri and is located posteriorly in the PLIC, and we also determined how age, sex, or handedness affected these locations. ⋯ The CST most frequently originates from both pre- and postcentral gyri, especially in older children, and is typically centered approximately two thirds of the distance from the anterior margin of the PLIC and occupies about a quarter of its anteroposterior length. In young children, the CST can often be seen originating exclusively from the precentral gyrus by DTI.
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AJNR Am J Neuroradiol · Oct 2009
Localization of the subthalamic nucleus: optimization with susceptibility-weighted phase MR imaging.
On clinical MR images, the subthalamic nuclei (STN) are poorly delineated from adjacent structures, impeding safe direct targeting for placement of electrodes in the treatment of Parkinson disease. Susceptibility-weighted MR phase imaging offers improved contrast and spatial resolution at reduced imaging times relative to clinically used T2-weighted spin-echo imaging for STN visualization. Our purpose was to assess STN visibility by using phase imaging, comparing phase and magnitude images obtained concurrently by using susceptibility-weighted imaging (SWI). The goal was to identify an efficient scanning protocol for high-quality phase images of STN. ⋯ Visualization and delimitation of STN was superior on phase images and was achieved at 3T in <2.5 minutes. A TE of 20 ms and an acceleration factor of
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AJNR Am J Neuroradiol · Oct 2009
Case ReportsA case of spinal cord infarction following lumbar transforaminal epidural steroid injection: MR imaging and angiographic findings.
Spinal cord infarction following lumbar transforaminal epidural steroid injection is a rare and devastating complication. We describe the case of a 55-year-old woman who developed spinal cord infarction following right L2-3 transforaminal epidural injection, diagnosed on the basis of clinical and MR imaging findings. Spinal angiography demonstrated occlusion of the right L2 segmental artery with reconstitution of the radicular branch from collaterals. The artery of Adamkeiwicz could not be demonstrated and was presumably occluded by the steroid injection.
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AJNR Am J Neuroradiol · Sep 2009
Motion of the cerebellar tonsils in the foramen magnum during the cardiac cycle.
Tonsil motion was measured with cine MR imaging in patients clinically suspected of having Chiari I malformation. Cardiac-gated sagittal 2D fast imaging employing steady-state acquisition (2D FIESTA) was performed in 11 patients with a Chiari I malformation and in 6 subjects without tonsil ectopia. Tonsil motion was measured through the cardiac cycle with a pixel-shift program designed for that purpose. ⋯ In patients with Chiari I and subjects with normal cerebellar tonsils, 2D FIESTA showed small-amplitude tonsil movement in cephalad and caudad directions during the cardiac cycle. The average total magnitude of motion was 0.43 mm in subjects with normal tonsils (controls) and 0.57 mm in patients with Chiari malformations, 33% greater than that in controls. Tonsil motion was 0.61 mm in the patients with syringomyelia and 0.50 mm in those without it (22% difference).