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  • 1
    Electronic Resource
    Electronic Resource
    Unraveling the Role of Structure and Density in Determining Vertebral Bone Strength (1997)
    Springer
    Calcified tissue international 61 (1997), S. 474-479 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Vertebral strength — Magnification radiographs — Texture — Quantitative computed tomography.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The strength of bone is determined not only by bone density but also by structure. Therefore, quantification of the structure in radiographs by texture parameters may result in a better prediction of fracture risk. Since in radiographs density and structure are strongly correlated, the predictive power of texture parameters should be corrected for the influence of BMD to determine the additional information conveyed by these parameters. In this study, we evaluated the predictive power of various texture parameters based on the Grey-Level Dependence Method and the Morphological Gradient Method. This study was performed on 67 vertebrae obtained from 20 male and 12 female human cadaver thoracolumbar spines. BMD and area of the vertebral body were determined from QCT images and texture parameters were derived from direct magnification (DIMA) radiographs. The fracture force, measured under conditions simulating the in vivo situation, was corrected with the area of the vertebra to yield the fracture stress (FS). Results of the study indicate that BMD correlates significantly with FS r= 0.82 (P 〈 0.001, n= 24) and r= 0.94 (P 〈 0.001, n= 43) for female and male vertebrae, respectively. Correlation coefficients of the investigated texture parameters were as high as 0.80 (P 〈 0.001) and 0.67 (P 〈 0.001) for the female and male vertebrae, respectively. Multiple regression analysis showed that in female vertebrae, the addition of one texture parameter to BMD results in a better prediction of strength. The multiple correlation coefficient was 0.87 (P 〈 0.001) in this case. In male vertebrae, BMD was the best predictor of fracture stress. These results suggest that texture parameters, as measured in magnification radiographs, can predict bone strength. Whereas in all cases BMD is the best single predictor of bone strength, for women texture parameters contain useful additional information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900370
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  • 2
    Electronic Resource
    Electronic Resource
    Vertebral Dimensions: Influence of X-Ray Technique and Patient Size on Measurements (1998)
    Springer
    Calcified tissue international 62 (1998), S. 214-218 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Vertebral dimension — Correction — Osteoporosis — Technique — Patient size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. In this study a new reference value, ``corrected vertebral dimension,'' is presented for vertebral height measurements. Of 68 females (age 18–88 years; mean 44.2 years) and 40 males (age 16–81 years; mean 55 years) the projected vertebral dimensions (T4–L5) were measured on lateral radiographs. In addition to this, the vertebra-to-film distances (VFD) were measured and a fixed focus-to-film distance (FFD) was used during the study. Corrected dimensions of the thoracic and lumbar vertebrae (T4–L5) were calculated using the FFD and VFD. These corrected dimensions were then used to recalculate projected vertebral dimensions at different focus-to-film distances. The applied geometric corrections were verified in a phantom study representing an in vitro situation. The results indicate that studies using different X-ray techniques for making lateral radiographs of the spine can become comparable when using corrected vertebral dimensions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900420
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  • 3
    Electronic Resource
    Electronic Resource
    Adaptive filtering of canine electrogastrographic signals. Part 1: system design (1981)
    Springer
    Medical & biological engineering & computing 19 (1981), S. 759-764 
    Details
    ISSN: 1741-0444
    Keywords: Adaptive filtering ; Electrogastrography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The study of the relation between gastric myo-electrical activities recorded from serosal and cutaneous electrodes is hindered by the poor quality of the cutaneous signal. This hindrance could be minimised by suitable filtering of the signal. Since it is not yet clear which aspects of the cutaneous signal constitute valuable information, the filter process should not affect phase, amplitude, frequency and waveform of the gastric component, while noise components should be suppressed strongly. The system design of a modified adaptive filter that meets these requirements is described. The filter was implemented on a digital Nova 2 minicomputer. the filter performance is described and tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441337
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  • 4
    Electronic Resource
    Electronic Resource
    Adaptive filtering of canine electrogastrographic signals. Part 2: filter performance (1981)
    Springer
    Medical & biological engineering & computing 19 (1981), S. 765-769 
    Details
    ISSN: 1741-0444
    Keywords: Adaptive filtering ; Electrogastrography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The modified adaptive filter method described in Part 1 was applied to 16 stretches of (cutaneous) electrogastrographic signal of 17·07 min duration. A signal-to-noise ratio improvement of about 8 dB was achieved. The most characteristic feature of the filter method appeared to be that wave-form and phase of the gastric component of the electrogastrographic signal are preserved. It is concluded that the use of the modified adaptive filter forms a valuable tool in the study of the electrogastrographic signal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441338
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  • 5
    Electronic Resource
    Electronic Resource
    Electrogastrography in the dog: waveform analysis by a coherent averaging technique (1983)
    Springer
    Medical & biological engineering & computing 21 (1983), S. 56-64 
    Details
    ISSN: 1741-0444
    Keywords: Coherent signal averaging ; Dog ; Electrogastrogram ; Waveform
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Electrogastrograms (e.g.g.s) recorded cutaneously in the dog were subjected to waveform analysis by coherent (or ‘triggered’) averaging techniques, to study the relation between e.g.g. waveforms and gastric contractile activity on the one hand, and the position of the cutaneous electrodes used to pick up the e.g.g. on the other. The trigger pulses used were picked up by electrodes applied to the serosal surface of the stomach. To make allowance for the influence of gastric contractions and the related electrical signals on the e.g.g. waveforms a computer program was developed to create a multicategory averager. Instead of adding all signal segments together, each segment was assigned to one of four categories, depending on the magnitude of the corresponding gastric contraction (as recorded by a force transducer applied to the stomach wall). The signal segments in each category were then averaged. The results of the analysis showed that both abdominal electrode position and magnitude of gastric contraction had a clear influence on e.g.g. waveforms. It was also concluded that, depending on the position of the abdominal electrodes, e.g.g. waveforms are related to either corporal or antral regions, or to both regions simultaneously.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02446407
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  • 6
    Electronic Resource
    Electronic Resource
    Running spectrum analysis as an aid in the representation and interpretation of electrogastrographic signals (1987)
    Springer
    Medical & biological engineering & computing 25 (1987), S. 57-62 
    Details
    ISSN: 1741-0444
    Keywords: Electrical control activity ; Electrical response activity ; Electrogastrography ; Fast Fourier transform ; Gastric myoelectrical activity ; Running spectrum analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The recording of gastric myoelectrical activity by means of cutaneous electrodes attached to the external abdominal wall is termed electrogastrography. Respiration and motion artefacts hamper the interpretation of electrogastrographic signals. Running spectrum analysis, using the fast Fourier transform, seems to provide a concise spectral representation of electrogastrographic data. In this paper the concept of running spectrum analysis is presented in detail using test signals consisting of frequency modulated sine waves and actual recordings from dog and man. Especially the visual interpretable representation in appropriate plots is emphasised and discussed. It is demonstrated that tachygastrias with a duration of the order of 30s can easily be recognised in the spectra. In most cases the gastric frequency can be recognised in the spectra. It is concluded, therefore, that running spectrum analysis has to be considered an attractive noninvasive method to study gastric myoelectrical activity in dog and man.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02442821
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