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31.
Model-based 3-D segmentation of multiple sclerosis lesions in magnetic resonance brain images 总被引:2,自引:0,他引:2
Kamber M Shinghal R Collins DL Francis GS Evans AC 《IEEE transactions on medical imaging》1995,14(3):442-453
Human investigators instinctively segment medical images into their anatomical components, drawing upon prior knowledge of anatomy to overcome image artifacts, noise, and lack of tissue contrast. The authors describe: 1) the development and use of a brain tissue probability model for the segmentation of multiple sclerosis (MS) lesions in magnetic resonance (MR) brain images, and 2) an empirical comparison of the performance of statistical and decision tree classifiers, applied to MS lesion segmentation. Based on MR image data obtained from healthy volunteers, the model provides prior probabilities of brain tissue distribution per unit voxel in a standardized 3-D "brain space". In comparison to purely data-driven segmentation, the use of the model to guide the segmentation of MS lesions reduced the volume of false positive lesions by 50-80% 相似文献
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Weaver M Arisaka K Roberts D Slater W Briere RA Cheu E Harris DA Roodman A Schwingenheuer B Wah YW Winstein B Winston R Barker AR Swallow EC Bock GJ Coleman R Crisler M Enagonia J Ford R Hsiung YB Jensen DA McFarland KS Ramberg E Tschirhart R Collins EM Gollin GD Nakaya T Yamanaka T Gu P Haas P Hogan WP Kim SK Matthews JN Myung SS Schnetzer S Somalwar SV Thomson GB Zou Y 《Physical review letters》1994,72(24):3758-3761
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Strachan JD Adler H Alling P Ancher C Anderson H Anderson JL Ashcroft D Barnes CW Barnes G Batha S Bell MG Bell R Bitter M Blanchard W Bretz NL Budny R Bush CE Camp R Caorlin M Cauffman S Chang Z Cheng CZ Collins J Coward G Darrow DS DeLooper J Duong H Dudek L Durst R Efthimion PC Ernst D Fisher R Fonck RJ Fredrickson E Fromm N Fu GY Furth HP Gentile C Gorelenkov N Grek B Grisham LR Hammett G Hanson GR Hawryluk RJ Heidbrink W Herrmann HW Hill KW Hosea J Hsuan H Janos A Jassby DL Jobes FC 《Physical review letters》1994,72(22):3526-3529
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High-purity Fe powder was mechanically milled under argon at ambient temperature using an SPEX 8000 mill. The local atomic and magnetic structure was studied using57Co/Fe Mössbauer and111In/Cd perturbed angular correlations (PAC) spectroscopies. After 32 hours of milling, X-ray diffraction revealed effective grain diameters of 18 nm and energy-dispersive X-ray analysis indicated a Cr impurity concentration of 5%, presumably introduced by mechanical attrition of steel ball bearings used for milling. In addition to a spectral component very similar to bulk iron metal, the Mössbauer spectra exhibited hyperfine field shifts attributed to the Cr impurities. PAC spectra on Fe milled for 5 h, with no contamination, exhibited two components: (1) A slightly broadened magnetic interaction attributed to interior, defect-free sites of In/Cd probes with a mean hyperfine field slightly greater than in macroscopic grains. The defect-free site fraction grew appreciably during milling, even though In is essentially insoluble in Fe. (2) An indistinct signal due to mixed magnetic and quadrupole interactions attributed to probes at surface or other defect sites. 相似文献
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Gu P Haas P Hogan WP Kim SK Matthews JN Myung SS Schnetzer S Thomson GB Zou Y Arisaka K Roberts D Slater W Spencer MB Weaver M Briere RA Cheu E Harris DA Krolak P McFarland KS Roodman A Schwingenheuer B Somalwar SV Wah YW Winstein B Winston R Barker AR Swallow EC Bock GJ Coleman R Crisler M Enagonio J Ford R Hsiung YB Jensen DA O'Dell VR Ramberg E Tschirhart R Collins EM Gollin GD Nakaya T Yamanaka T 《Physical review letters》1996,76(23):4312-4315
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Poly(vinyl acetates) with either isopropylol or (1-hydroxyethyl)-2-oxyisopropanyl end groups were analysed by tandem mass spectrometry using a quadrupole-time-of-flight (Q-TOF) instrument. Random scission along the polymer backbone was not observed. Instead the initial scissions were derived from the cleavage of end-group species. The resultant macrocations were subject to further elimination reactions that eventually produced polyene macrocations. A smaller fraction of the initial macrocations also reacted by loss of ketene and this reaction produced macrocations containing vinyl alcohol units. 相似文献
40.
Michael J. Beam Jeannette Schulz Anvita Sinha Pamela Collins Susan Hallenbeck Michael Kustin 《Journal of heterocyclic chemistry》1989,26(2):521-524
Notwithstanding its tendency toward air oxidation in solution, 2-hydrazinobenzothiazole I reacted with aromatic aldehydes in ethanol to give the corresponding hydrazones III-XV in high yields and analytical purity. In related examples, acylation took place under similar conditions to produce hydrazides XVI-XX . The near-infrared bands of the absorption spectra of the araldehyde hydrazones have been associated with charge transfer and appeared to correlate with structural elements of the compounds in a way suggesting that the charge transfer was intermolecular. 相似文献