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Katsuhiro Kobayashi DG Tomoyuki Nakahori Iori Ohmori Harumi Yoshinaga Yoko Otsuka Eiji Oka Shunsuke Ohtahara 《Brain topography》1996,9(2):125-134
Summary We have produced a method to estimate ictal localized epileptic activity hidden among the background in scalp EEGs. When the visually completely different waveforms of the epileptic and background activities are nearly orthogonal, epileptic activity may be approximately extracted from the EEG data matrix by singular value decomposition with subsequent orthogonal rotation to match the distribution of one component with that of the epileptic source. A simulation study was carried out using a matrix mimicking the scalp EEG with an inconspicuous ictal epileptic activity from a dipole source. This hidden epileptic activity was approximately recovered by matching the dipole of interest with the epileptic dipole, even when the simulated waveforms of the epileptic and background activities were not exactly orthogonal. High linear correlation between these two types of waveforms hampered the recovery of the epileptic activity. In another simulation study employing two epileptic dipoles producing activities with the same waveform and a brief time lag, it was indicated that the temporal relationship between the epileptic activities could be also estimated using the cross-correlation function. In the preliminary clinical application of this method to the ictal EEGs of complex partial seizures, rhythmic activities with seemingly epileptic waveforms were estimated at the dipoles which were located in the vicinity of cortical lesions revealed by neuroimaging studies. These activities were indicated to appear before any change in the scalp EEG. We hope for the clinical application of this method for noninvasive estimation of inconspicuous ictal epileptic activity.The authors thank Prof. Peter K.H. Wong of the Department of Paediatrics, University of British Columbia, Canada, and Prof. Yutaka Tanaka and Mr. Kim Hyun Bin of the Department of Environmental and Mathematical Sciences, Faculty of Environmental Science and Technology, Okayama University, Japan, for their technical suggestions. This study was aided by a grant from the Japan Epilepsy Research Foundation. 相似文献
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Mitchell DG; Merton D; Needleman L; Kurtz AB; Goldberg BB; Levy D; Rifkin MD; Pennell RG; Vilaro M; Baltarowich O 《Radiology》1988,167(2):303-306
Color Doppler imaging (CDI) can demonstrate the relative direction and velocity of blood flow in color, superimposed on a conventional gray-scale ultrasound image that depicts stationary tissue. Twenty-five infants were studied with portable CDI in the coronal, sagittal, and axial planes. Bilateral antegrade flow was noted in the anterior, middle, and posterior cerebral arteries in all patients. Multiplanar CDI can image flow in the circle of Willis and its tributaries and branches. 相似文献
66.
Complications of spinal cord arteriography: prospective assessment of risk for diagnostic procedures
Forbes G; Nichols DA; Jack CR Jr; Ilstrup DM; Kispert DB; Piepgras DG; Wiebers DO; Earnest F th; Axley PL 《Radiology》1988,169(2):479-484
A prospective study was done of complications associated with 134 consecutive diagnostic spinal cord arteriograms in 96 patients (63 men and 33 women aged 17-78 years). Patients were examined for either arteriovenous malformation (n = 88) or tumor (n = 8), as indicated by myelography. Among the complications, 11 (8.2%) were local, five (3.7%) were systemic nonneurologic, and three (2.2%) were neurologic (two were associated with full recovery in less than 24 hours, and one was associated with full recovery in less than 1 week). No specific clinical or technical factors were significantly associated with the development of neurologic complications. Details of the clinical profile, angiographic technique, and pathologic findings for each patient were recorded and analyzed with respect to the potential risk for arteriographic complications. Diagnostic spinal cord arteriography had an acceptable risk within the range of other neuroangiographic diagnostic procedures. 相似文献
67.
Spacing of cytochrome oxidase blobs in visual cortex of normal and strabismic monkeys 总被引:3,自引:3,他引:0
Murphy KM; Jones DG; Fenstemaker SB; Pegado VD; Kiorpes L; Movshon JA 《Cerebral cortex (New York, N.Y. : 1991)》1998,8(3):237-244
Some models of visual cortical development are based on the assumption that
the tangential organization of V1 is not determined prior to visual
experience. In these models, correlated binocular activity is a key element
in the formation of visual cortical columns, and when the degree of
interocular correlation is reduced the models predict an increase in column
spacing. To examine this prediction we measured the spacing of columns, as
defined by cytochrome oxidase (CO) blobs, in the visual cortex of monkeys
whose binocular vision was either normal or disrupted by a strabismus. The
spatial distribution of blobs was examined in seven normal and five
strabismic macaques. Tangential sections through the upper layers of the
visual cortex were stained to reveal the two-dimensional (2D) pattern of CO
blobs. Each blob was localized and their center-to-center spacing, packing
arrangement and density were calculated using 2D nearest-neighbor spatial
analyses. The mean center-to-center spacing of blobs (590 microm for
normally reared and 598 microm for strabismic macaques) and the mean
density of blobs (3.67 blobs/mm2 for normally reared and 3.45 blobs/mm2 for
strabismic macaques) were not significantly different. In addition, the 2D
packing arrangement of the blobs was not affected by strabismus. While it
is clear that neural activity plays a key role in the elaboration and
refinement of ocular dominance cortical modules, we conclude that it does
not determine the spatial period of the pattern of CO blobs. This suggests
that aspects of the neural circuitry underlying the columnar architecture
of the visual cortex are established prenatally and its fundamental
periodicity is not modifiable by experience.
相似文献
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Klatskin tumors of the bile ducts: sonographic appearance 总被引:4,自引:0,他引:4
The authors present 3 cases of surgically proved Klatskin tumor diagnosed by ultrasound alone. Sonographic features of these tumors include (a) dilatation of the intrahepatic biliary ducts but not the extrahepatic duct, (b) non-union of the right and left hepatic ducts, and (c) small, solid masses at the hepatic hilus. Local spread to the liver may also be seen. If the pancreas appears normal and no primary tumor can be found, Klatskin tumor can be diagnosed with a high degree of accuracy. 相似文献