Variability of quantitative echographic parameters of the liver: Intra- and interindividual spread, temporal-and age-related effects
| Autor: | G.J.E. Rosenbusch, P.C. Hartman, B.J. Oosterveld, Johan M. Thijssen |
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| Rok vydání: | 1991 |
| Předmět: |
Adult
Aging medicine.medical_specialty Acoustics and Ultrasonics Statistics as Topic Biophysics Time gain compensation Biology Region of interest Age related Internal medicine Image Processing Computer-Assisted medicine Humans Radiology Nuclear Medicine and imaging Circadian rhythm Aged Ultrasonography Morning Aged 80 and over Observer Variation Radiological and Ultrasound Technology business.industry Healthy subjects Reproducibility of Results Middle Aged Regression Circadian Rhythm Endocrinology Liver Attenuation coefficient Nuclear medicine business |
| Zdroj: | Ultrasound in Medicine & Biology. 17:857-867 |
| ISSN: | 0301-5629 |
| Popis: | The values of acoustic and image texture parameters were estimated from liver scans of healthy subjects. The values were obtained after appropriate preprocessing of the radio frequency echograms by an on-line computerized system. The preprocessing comprised a correction for the Time Gain Compensation (TGC), the beam diffraction and the frequency dependent attenuation in the Region of Interest (ROI). The intra- and interindividual variability of the parameter values appeared to be of the same order of magnitude, but significantly larger than the variability assessed by measurements of a homogeneously scattering tissue mimicking phantom. Significant temporal effects were found for all the parameters, which consistently occurred during the morning. These results are discussed in relation to the circadian rhythm of the glycogen content and of the hepatic circulation. All the parameters appeared to be significantly correlated to age. The slope of the regression ranged from 3.6% per decade (attenuation coefficient) to 7.6% per decade (mean echolevel). A tentative explanation to these results is presented: the increased stiffness of hepatic vasculature with age. |
| Databáze: | OpenAIRE |
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