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  • 1990-1994  (2)
  • 1980-1984
  • Speed-of-sound  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 54 (1994), S. 91-95 
    ISSN: 1432-0827
    Schlagwort(e): Fat ; Ultrasound attenuation ; Speed-of-sound ; Os calcis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract Measurements of the speed-of-sound (SOS) and of the broadband ultrasound attenuation (BUA) on the os calcis were recently proposed to assess osteoporotic fragility. Velocity and attenuation were measured through the heel which can be divided in three phases including hydroxyapatite, soft tissue, and fat. The aim of this study was to evaluate the influence of fat composition and heel width on SOS and BUA. This influence was determined from both in vitro investigations examining fat samples, phantoms, and cadaver heels, and in vivo ones observing adult volunteers as well as a wide sample section of healthy elderly women. Ultrasound velocities on various fat samples were significantly lower than those on distilled water (-65 m/second to -123 m/second). The excision of the surrounding soft tissue from cadaver heels made SOS steadily increase whereas the insertion of a 10 mm piece of lard in the lateral face of cadavers' and volunteers' heels os calcis lowered SOS about 30 m/second. ond. Furthermore, a difference of SOS was estimated at 15 m/second for a 12.5% variation of the marrow fat weight. Among 334 elderly and healthy women aged 75 and over, a significant negative correlation was found between SOS and heel width (r=-0.27; P〈0.0001). On the other hand, fat composition had no significant effect on BUA measurement, and no significant relationship was found between BUA and heel width. This study demonstrates that an increase of heel width and fat thickness provides an underestimation of os calcis SOS, but has no significant effect on BUA.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-0827
    Schlagwort(e): Broadband ultrasound attenuation ; Speed-of-sound ; Stiffness index ; Interunit precision
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract Ultrasonic assessment is a new approach to assess both quality and density. Two ultrasonic parameters are measured on the os calcis: the attenuation or broadband ultrasound attenuation (BUA) and the velocity or speed of sound (SOS). The interunit variations in vitro and in vivo of an ultrasound instrument, the Lunar AchillesR system, used in a French multicenter study named EPIDOS, were calculated and the stability of these intruments over a 12-month period was evaluated. A third parameter called “stiffness index”, calculated from the SOS and BUA, was also used in this study. The average CV in vitro for the BUA and SOS was 0.92% and 0.12%, respectively, and the average CV in vivo for the BUA, the SOS, and the stiffness index was 1.83%, 0.23%, and 1.9%, respectively. The interunit (or inter-machines) variations were calculated by a one-way analysis of variance. We detected small but significant measurement differences among centers on a phantom for both SOS (maximum significant difference 0.4%) and stiffness (maximum significant difference 3.5%) but not for BUA. Similar diffrences were found in vivo. The precision over 12 months of the interunit variations in vitro was evaluated by measuring a single phantom traveling from one center to another several times. The range of the CV for the BUA (1.54–0.51%), for the SOS (0.25–0.14%), and for the stiffness index (2.26–1.10%) are explained in part by technical failures. The variation among the five Achilles was estimated by the combined CV which was 1.42% for the BUA, 0.32% for the SOS, and 2.33% for the stiffness index. In conclusion, our findings indicate that equipment from one manufacturer appears to be consistent between machines for the BUA, but not completely for the SOS. The results for this stiffness index are necessarily influenced by both SOS and BUA. The shortterm and long-term interunit precision is good, both in vitro and in vivo. Such results provide increased confidence in multicenter clinical trials where ultrasonic data are pooled.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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