Assessment of bone status using speed of sound at multiple anatomical sites

Studies in vitro and in vivo have shown that quantitative ultrasound (QUS) is a valid tool for the assessment of bone status. Current QUS methods usin g the transmission technique are limited to one peripheral bone site. A new system, Sunlight Omnisense (TM) (Omnisense, Sunlight Medical Ltd., Rehovot , Israel), measures speed of sound (SOS, in m/s) along the surface of the b one based on an axial transmission technique. The Omnisense (TM) can measur e SOS at several anatomical sites. This study evaluated the SOS at differen t anatomical sites In a healthy population. A total of 334 adult women from three research centers in the USA and Canada with a mean (+/- SD) age of 4 8.8 (+/- 17.4) years were enrolled in this study. SOS was measured at the p roximal third phalanx, distal one third radius, midshaft tibia, and fifth m etatarsal. The mean SOS ( SD) values for the phalanx, radius, tibia and met atarsal were 3984 (+/- 221), 4087 (+/- 147), 3893 (+/- 150) and 3690 (+/- 2 46) m/s, respectively. Each anatomical site SOS was significantly different (p < 0.001) from that of the other sites. SOS at the different anatomical sites was modestly, but significantly, correlated (r = 0.31 to 0.56, p < 0. 001). Similar correlation coefficients were obtained for the T scores. The mean T scores for subjects over the age of 60 years were -1.94, -2.01, -0.9 7 and -1.42 for the phalanx, radius, tibia and metatarsal, respectively. Th e age of peak SOS and the rate of change thereafter varied with anatomical site, implying that the prevalence of osteopenia and osteoporosis was site- dependent if only one T score cut-off point was used. Comparing individuals , 10% to 17% of patients had T scores that differed by more than a factor o f 2 between sites. Weight and age were some of the contributing factors to this heterogeneity. The Omnisense (TM) provides an opportunity to assess bo ne status at different anatomical sites. Whether or not combining measureme nts from all these anatomical sites will improve osteoporosis management st ill needs to be determined. (C) 2001 World Federation for Ultrasound in Med icine & Biology.