Cortical stroke was produced in rats by cautery occlusion of the middle cerebral artery distal to the lenticulostriate origins. Brains were removed, and nuclear magnetic resonance (NMR) scans of whole fixed brains and in vitro measurements of small samples were obtained. Brain tissue was then processed for histology. Routine scans used a modified spin-echo… (More)
A prospective clinical study was performed in 32 patients with multiple sclerosis (MS) to evaluate the sensitivity of lesion detection and accuracy of lesion localization by neurologic examination, delayed enhanced computed tomography (CT) with a double dose of contrast material, and proton magnetic resonance (MR) imaging. After neurologic examination… (More)
Magnetic Resonance Imaging (MRI) affords a considerable improvement in image contrast over other methods by virtue of the intrinsic NMR parameters spin density, T1, and T2. However, the clinical utility of routine quantification of these parameters is currently unknown. Calculated T2 images might afford additional disease specific information provided the… (More)
We present a method for producing accurate calculated T1 and spin density nuclear magnetic resonance images. A modified Carr-Purcell-Meiboom-Gill pulse sequence is used to obtain a series of images containing both T1 and T2 dependence. The image series is first analyzed to remove the T2 dependence. The resulting images are then analyzed, pixel by pixel, to… (More)
One of the important characteristics of a computed tomography scanner is the image slice thickness. Most phantoms designed to measure this parameter do so with a ramp or tilted wire. Such a phantom must be precisely aligned to avoid possible significant inaccuracy. We present here a procedure for measuring the image slice thickness using a phantom… (More)
Two of the AAPM CT performance phantom inserts require precise alignment. We present a method for aligning an insert which makes use of the partial volume effect. We demonstrate that the procedure is sensitive to tilts of less than one degree and, using the slice thickness insert, allows reproducible positioning.