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Apparent diffusion coefficients (ADC) were measured in a rat spinal cord weight-drop injury model. After sacrifice, the spinal cords were fixed in situ and excised for MR imaging and ADC measurement. Diffusion is anisotropic in normal gray and white matter. There were significant decreases in ADCs measured along the longitudinal axis of the injured cord and(More)
To investigate the role of MR imaging in wallerian degeneration, a series of animal models of increasingly complex peripheral nerve injury were studied by in vivo MR. Proximal tibial nerves in brown Norway rats were either crushed, transected (neurotomy), or transected and grafted with Lewis rat (allograft) or brown Norway (isograft) donor nerves. The(More)
Zero-mean noise introduced into quadrature detected MRI signals is generally rectified by the reconstruction algorithm to give a nonzero background intensity in the displayed image. In low signal-to-noise ratio (SNR) images, this background will inflate region of interest (ROI) signal measurements, leading to improper T2 and diffusion fits. A method is(More)
We have developed an implanted radiofrequency coil to obtain high resolution in vivo MR images at 1.9 Tesla of rat spinal cords that have been injured using a standardized weight drop technique. The signal-to-noise ratio and motion artifact suppression of these images is superior to that achieved in earlier attempts at this field strength using an external(More)
Magnetic resonance (MR) imaging was used to evaluate normal fetal intracranial anatomy in axial, coronal, and sagittal planes. The T1 and T2 weighted images (WI) of aborted fetuses of varying gestational ages were correlated with anatomic sections. In the premature fetus three distinct intensity zones were seen on MR that were not visualized on gross(More)
Human and rat cervical spinal cords were imaged with high-resolution spin-echo and inversion-recovery pulse sequences in an experimental 1.9-T MR system. The gross morphology of the cord was easily discernible in fresh and fixed specimens, including the white and gray commissures, dorsal and ventral horns, and lateral and posterior funiculi. The T1, T2, and(More)
Most fast-imaging sequences use gradient echoes and a low flip-angle excitation. The low flip angle is used because it gives increased signal when TR less than T1. However, spin-echo sequences are less productive of certain artifacts, among them flow and magnetic susceptibility artifacts. We present a modification of the spin-echo pulse sequence designed to(More)
Computed tomographic (CT) measurements of the thoracic spine and its contents were obtained in 33 patients undergoing metrizamide myelography for various spinal disorders. Twenty-eight of these patients had symptoms referable to the cervical or lumbar region and form the basis of this study. Five patients had symptoms referable to the thoracic spine.(More)