Comparison of ultrasound and X-ray absorptiometry bone measurements in a case control study of female rheumatoid arthritis patients and randomly selected subjects in the population

To compare quantitative ultrasound (QUS) and dual-energy X-ray absorptiometry (DXA) bone measurements in female rheumatoid arthritis (RA) patients and controls were randomly selected from the population; secondly, to examine disease and demographic factors associated with these bone measurements. In a total of 115 RA patients (mean age 63.0 years) and 115 age- and gender-matched controls demographic and clinical variables were collected and heel QUS parameters [speed of sound (SOS), broadband ultrasound attenuation (BUA) and stiffness index (SI)] as well as DXA bone mineral density (BMD) at spine and hip were measured. The differences in QUS and DXA measurements between RA patients and controls were tested both on a group and on an individual level. Univariate and multivariate statistical tests were applied to explore for associations to the bone measurements. In the RA patients mean disease duration was 16.6 years, erythrocyte sedimentation rate 23.6 mm/h, M-HAQ 1.68, 28-swollen joint count 7.7, 18-deformed joint count 4.5, 50.0% were rheumatoid factor (RF) positive and 44.2% were current users of prednisolone. All bone measurements were reduced in RA patients compared with controls (SOS 1.9%, BUA 9.4%, SI 19.5%, femoral neck BMD 7.4%, total hip BMD 7.5%, spine L2-L4 BMD -3.0%). Only at spine was the BMD reduction not statistically significant ( P=0.21). In the subgroup of never users of prednisolone SOS was decreased by 1.4%, BUA by 3.7%, SI by 11.0, femoral neck BMD by 2.7%, and total hip BMD by 0.6%, whereas for spine L2-L4 BMD was increased by 4.3% and only for SOS and SI was the decrease statistically significant. The QUS discriminated better than DXA between patients and controls on a group level, but this difference in favor of QUS disappeared on an individual level when the measurement errors were taken into account. Age, BMI, RF and deformed joint count, but not corticosteroids, were independently associated with at least one of the QUS and one of the DXA measures; however, the association between disease-related variables was stronger with the QUS bone measures than with the DXA bone measures. The results for the quantitative QUS bone measures seem to mainly reflect bone mass. Disease-related variables in multivariate analysis remained independently associated with all QUS measures even when adjusting for DXA bone measures. Further studies are needed to examine if QUS may reflect other aspects than bone mass and be a potential better predictor for fracture risk in RA and corticosteroid-induced osteoporosis.     

Bone mineral density in prepubertal obese and control children: relation to body weight,lean mass,and fat mass

The aim of the study was to determine the influence of obesity on bone status in prepubertal children. This study included 20 obese prepubertal children (10.7 +/- 1.2 years old) and 23 maturation-matched controls (10.9 +/- 1.1 years old). Bone mineral area, bone mineral content (BMC), bone mineral density (BMD), and calculation of bone mineral apparent density (BMAD) at the whole body and lumbar spine (L1-L4) and body composition (lean mass and fat mass) were assessed by DXA. Broadband ultrasound attenuation (BUA) and speed of sound (SOS) at the calcaneus were measured with a BUA imaging device. Expressed as crude values, DXA measurements of BMD at all bone sites and BUA (69.30 versus 59.63 dB/MHz, P < 0.01) were higher in obese children. After adjustment for body weight and lean mass, obese children displayed lower values of whole-body BMD (0.88 versus 0.96 g/cm2, P < 0.05) and BMC (1190.98 versus 1510.24 g, P < 0.01) in comparison to controls. When results were adjusted for fat mass, there was no statistical difference between obese and control children for DXA and ultrasound results. Moreover, whole-body BMAD was lower (0.086 versus 0.099 g/cm3, P < 0.0001), whereas lumbar spine BMAD was greater (0.117 versus 0.100 g/cm3, P < 0.001) in obese children. Thus, it was observed that, in obese children, cortical and trabecular bone displayed different adaptation patterns to their higher body weight. Cortical bone seems to enhance both size and BMC and trabecular bone to enhance BMC. Finally, considering total body weight and lean mass of obese children, these skeletal responses were not sufficient to compensate for the excess load on the whole body.     

Preliminary evaluation of a new ultrasound bone densitometer

Summary A new ultrasound bone densitometer has been developed that measures ultrasonic properties of the os calcis, namely, the speed of sound (SOS), broadband ultrasound attenuation (BUA), and a proprietary factor derived from SOS and BUA, termed stiffness. Short-term precision of ultrasound measurements was 1.4% for BUA, 0.2% for SOS, and 1.5% for stiffness in healthy women, and 1.1% for BUA, 0.1% for SOS, and 1.5% for stiffness in osteopenic women. One hundred seven women underwent measurements by ultrasound, together with dual energy X-ray absorptiometry (DXA) bone mineral density (BMD) measurements of the lumbar spine and proximal femur. Correlations between SOS, BUA, and stiffness measurements and DXA BMD measurements were all highly significant (P < 0.001) with r values varying from 0.54 to 0.67. BUA, SOS, and stiffness measurements were all significantly different between normal and osteopenic women even after adjusting for age, height, and weight (P < 0.05,P < 0.001, andP < 0.01, respectively). These results demonstrate that this ultrasound system measures ultrasonic properties of the os calcis with good precision, the measurements correlate moderately well with DXA BMD measurements and they can differentiate between normals and those with osteopenia.     

Influence of Physical Activity on Ultrasound and Dual-Energy X-ray Absorptiometry Bone Measurements in Peripubertal Girls: A Cross-Sectional Study

The aim of this cross-sectional study was to investigate whether two types of physical exercise affect the growing skeleton differently. We used calcaneal quantitative ultrasound measurements (QUS) and dual-energy X-ray absorptiometry (DXA) for measurement of bone mineral density (BMD), and to test how QUS values reflect the axial DXA values in these various study groups. A total of 184 peripubertal Caucasian girls aged 11–17 years (65 gymnasts, 63 runners, and 56 nonathletic controls) were studied. Weight, height, stage of puberty, years of training, and the amount of leisure-time physical activity were recorded. Broadband ultrasound attenuation (BUA) and sound of speed (SOS) through the calcaneus were measured. The BMD of the femoral neck and the lumbar spine were measured by DXA. The differences in mean values of bone measurements among each exercise group were more evident in pubertal than prepubertal girls. The mean BUA and SOS values of the pubertal gymnasts were 13.7% (77.8 dB/MHz versus 68.4 dB/MHz, P < 0.05) and 2.2% (1607.7 m/s versus 1572.4 m/s, P < 0.001) higher than of the controls, respectively. The mean BMD of the femoral neck in the pubertal gymnasts and runners was 20% (0.989 g/cm² versus 0.824 g/cm², P < 0.001) and 9.0% (0.901 g/cm² versus 0.824 g/cm², P < 0.05) higher than in the controls, respectively. The amount of physical activity correlated weakly but statistically significantly with all measured BMD and ultrasonographic values in the pubertal group (r = 0.19–0.35). The correlation between ultrasonographic parameters and BMD were weak, but significant among pubertal runners (r = 0.47–0.55) and controls (r = 0.39–0.42), whereas the DXA values of the femoral neck and the ultrasonographic parameters of the calcaneus did not correlate among highly physically active gymnasts. By stepwise regression analysis, physical activity accounted for much more of the variation in the DXA values than the ultrasonographic values. We conclude that the beneficial influence of exercise on bone status as measured by ultrasound and DXA was evident in these peripubertal girls. In highly active gymnasts the increase of the calcaneal ultrasonographic values did not reflect statistically significantly the BMD values of the femoral neck. Received: 28 June 1999 / Accepted: 2 November 1999     

Diagnostic value of ultrasound analysis and bone densitometry as predictors of vertebral deformity in postmenopausal women

Bone fractures depend not only on bone density, but also on bone quality. Ultrasound (US) has been proposed as a technique for evaluating skeletal status. Speed of sound (SOS) and broadband ultrasound attenuation (BUA) are the US properties currently used to assess bone strength and fragility. In 304 postmenopausal women (age 58.8±5.5 years) we measured: bone mineral density (BMD) of the lumbar spine (by dual-energy X-ray absorptiometry), SOS, BUA and Stiffness in the os calcis (using an Achilles machine). In all subjects we performed lateral lumbar and thoracic radiographs. Morphometric parameters were derived by measuring the anterior, middle and posterior height of each vertebral body, to obtain a semiquantitative grading of vertebral fractures as follows: 0, no vertebral deformity; 1, any vertebral height reduced between 20% and 25%; 2, any vertebral height reduced between 25% and 40%; 3, any vertebral height reduced more than 40%. On the basis of the number and severity of vertebral deformities the women were divided into: group 1 (n=79), normal; group 2(n=80), mild; group 3 (n=85), moderate; and group 4 (n=60), severe. Mean values of SOS, BUA, Stiffness and BMD were significantly lower (p<0.001) in women with vertebral deformity than in normals. In the whole population SOS, BUA and Stiffness values were significantly correlated with BMD. SOS, BUA and Stiffness values were significantly decreased (p<0.001) with vertebral deformity, as was BMD. Receiver operating characteristic (ROC) curve analysis showed BMD to be slightly better than Stiffness in discriminating among groups. Logistic regression analysis showed that BMD, BUA, SOS and Stiffness were independent predictors of vertebral fracture risk. Ultrasound parameters were still significant independent predictors of vertebral fracture even after adjusting for BMD.     

Stiffness in Discrimination of Patients with Vertebral Fractures

We measured the ultrasound parameters of the heels of 49 women with vertebral fractures and 87 age-matched controls using an Achilles ultrasound device. Average broadband ultrasound attenuation (BUA), speed of sound (SOS) and Stiffness were significantly lower in fracture patients (p<0.0001). We also estimated the ultrasound parameters of patients compared with age-matched non-fracture controls and found the mean BUA to be −1.02 SD below control values. The mean SOS was −0.97 SD and the mean Stiffness was −1.12 SD below control values.  Femoral bone mineral density (BMD) at the neck, Ward’s triangle and the trochanter, the total-body BMD and L2–4 BMD were measured with dual-energy X-ray absorptiometry (DXA) and found to be significantly lower in fracture patients (p<0.0001). All correlation coefficients between ultrasound parameters and DXA measurements were >0.5 and statistically significant (p<0.0001). A stepwise logistic regression with presence or absence of vertebral fracture as the response variable and all ultrasound – DXA parameters as the explanatory variables indicated that the best predictor of fracture was Stiffness, with additional predictive ability provided by spine BMD. Sensitivity and specificity of all measures were determined by the areas under the receiver operating characteristic (ROC) curve, which were 0.76 ± 0.04 for BUA, 0.77 ± 0.04 for SOS, 0.78 ± 0.04 for Stiffness and 0.78 ± 0.03 for spine BMD. The areas under the ROC curves of BUA, SOS, Stiffness and spine BMD were compared and it was found that Stiffness and spine BMD were significantly better predictors of fracture than BUA and SOS. These results support many recent studies showing that ultrasound measurements of the os-calcis have diagnostic sensitivity comparable to DXA, and also demonstrated that Stiffness was a better predictor of fracture than spine BMD. Received: 23 September 1997 / Accepted: 10 April 1998     

Comparison of calcaneus ultrasound and dual X-ray absorptiometry in children at risk of osteopenia.

The optimal method to assess pediatric bone mass remains controversial. Dual X-ray absorptiometry (DXA) is used most commonly for clinical assessments in children, but calcaneus ultrasound (CUS) is less costly, is free of ionizing radiation, and predicts fracture as well as DXA in adults. This study was designed to compare CUS and DXA in 42 young patients (ages 9-21) with chronic disease and/or fragility fractures. Zscores for broadband ultrasound attenuation (BUA) and speed of sound (SOS) determined using the Lunar Achilles Plus ultrasonometer were compared with Z-scores for areal bone mineral density (BMD) and volumetric BMD using DXA (Hologic). Logistic regression was employed to predict low bone density measured by DXA (defined as spinal BMD Z-score < -2) from CUS measurements. Sensitivity/specificity analysis was performed to compare CUS and spinal DXA Z-scores as predictors of previous low-impact fracture. Correlations between CUS and DXA Z-scores were in the range of r = 0.3-0.6. Areas under the receiver operator characteristic (ROC) curves for BUA and SOS predicting low bone density by DXA were similar: 0.81 and 0.82, respectively. ROC curve areas for spinal DXA, BUA, and SOS predicting previous fracture were also similar: 0.85, 0.84, and 0.84, respectively. While CUS correlates only modestly with DXA, ROC curve areas indicate that CUS detects low bone mineral in children with fragility fractures as well as DXA and may be a viable initial screen for osteopenia.     

Ultrasound bone measurement in pediatric subjects

Ultrasound bone measurement in healthy (n=71) and osteopenic (n=18) children aged 6 through 13 years of both sexes has been evaluated using the Achilles densitometer (Lunar Corporation). Measurements on the os calcis included speed of sound (SOS), broadband ultrasound attentiation (BUA), and a calculated stiffness index. The Achilles was adapted for children by a special positioning procedure that included the use of foot shims, and beam collimation on the receiving transducer. The precision of ultrasound results was comparable to that in adults (0.2% for SOS, 1.5% for BUA, and 1.8% for stiffness). SOS, BUA, and stiffness values increased with age in both sexes. Ultrasound measurements were correlated with bone mineral density (BMD in g/cm²) of the heel, AP spine (L2–L4), and total body by dual X-ray absorptiometry (DXA) densitometry (Lunar DPX-L). SOS, BUA, and stiffness measurements were significantly lower in osteopenic children (Z-1.9 to-2.5) (P<0.0001) than in normal age-matched controls. Total body BMD showed a higher Z-score than stiffness (-3.3 versus -2.5), but stiffness showed a greater percentage decrease (-30% versus -18%). In conclusion, ultrasound measurements of bone in children provide both good precision and discrimination of normals from osteopenic patients.     

Ultrasound and dual X-ray absorptiometry densitometry in women with hip fracture

To assess the usefulness of the measurement of the os calcis by ultrasound, a method that probably reflects bone quality as well as density, we have studied 54 women with hip fracture of the proximal femur and a control group. Ultrasound evaluation of the os calcis [broadband ultrasound attenuation (BUA), speed of the sound (SOS), and a combined index (stiffness)], and bone mineral density (BMD) determination over the proximal femur by dual X-ray absorptiometry (DXA) were performed. Weight, BMD, and ultrasound values in the hip fracture patients were significantly lower than controls (P<0.001). The Z-scores for BUA and stiffness were not different than that for femoral neck. Ward's triangle or trochanteric BMD (between-1.7 and -1.5). The odds ratios determined by receiver-operating characteristics (ROC) analysis were greater at the femoral neck (25.1) and BUA (24.4). Intermediate values were found at stiffness (16.9), Ward's triangle (12.8), and trochanter (11.1), and lower values were obtained at SOS (4.2). In turn, patients with trochanteric hip fractures had a significantly lower femoral neck and Ward's triangle BMD, stiffness, and BUA than patients with cervical hip fractures. Comparing a subgroup of 30 women with hip fractures without vertebral fractures with an age-matched group of 87 women with osteoporotic vertebral fractures, both groups were of similar weight and BMD but all ultrasound values were significantly lower in the hip fractures compared with vertebral fracture patients (P<0.05-P<0.01). Our findings suggest that in women with hip fractures, ultrasound evaluation of the os calcis has diagnostic sensitivity comparable to DXA of the femur and could be useful to predict hip fracture risk. Ultrasound values are lower in hip fractures compared with vertebral fracture, age-matched women and in older compared with younger hip fracture patients.     

Evaluation of quantitative ultrasound and dual X-Ray absorptiometry measurements in women with and without fractures.

Dual X-ray absorptiometry (DXA) is considered a gold standard for bone measurements in the assessment of osteoporosis. Other techniques such as quantitative ultrasound (QUS) are promising to detect patients with osteoporosis-related fractures and to predict fracture risk. In this cross-sectional retrospective study, we analyzed the behavior of QUS and DXA measurements alone and in combination with regard to the presence of fractures in 320 women, 147 with nontraumatic fractures. Speed of sound (SOS), broadband ultrasound attenuation (BUA), and a third parameter derived from SOS and BUA called stiffness were measured at the calcaneus using an Achilles device (Lunar, Madison, WI). Lumbar (BMDL) and hip (BMDH( bone mineral density were measured by DXA (Hologic QDR 1000, Waltham, MA). Mean SOS, BUA, stiffness, and BMDL and BMDH were significantly lower in women with fractures compared with women without fractures. Logistic regression adjusted for age identified stiffness as the parameter most strongly associated with the presence of fracture: its sensitivity was 54% and specificity 70%. Hip BMD was second, with a sensitivity of 54% and a specificity of 69%. Combining QUS and DXA measurements did not improve the specificity nor the sensitivity. There was no difference in the odds ratios with regard to the technique that was chosen for bone assessment. In conclusion, these results suggest that low QUS measurements are associated with the presence of fractures in a way similar to DXA. In our study, the combination of QUS and DXA did not improve the discrimination of women with fractures.     

A method for the estimation of femoral bone mineral density from variables of ultrasound transmission through the human femur

Quantitative ultrasound (QUS) measurements at peripheral sites can be used to estimate osteoporotic fracture risk. However, measurements at these sites are less suitable to predict bone mineral density (BMD) or fracture risk at the central skeleton. We investigated whether direct QUS measurements at the femur would allow to estimate dual X-ray absorptiometry (DXA) BMD of the total proximal femur with errors comparable to established DXA accuracy errors. Two independent sets of femora were measured in Kiel (6 f, 4 m, age: 55-90) and Paris (19 f, 20 m age: 45-95) using different benchtop systems in the two laboratories. The femora were scanned in transverse transmission mode using focused US transducers of 500 kHz center frequency. The QUS values were averaged over a region similar to the total hip region of dual X-ray absorptiometry (DXA) measurements. BMD was measured using DXA. SOS and BMD correlated significantly (p<0.0001) in both data sets (R2=0.81-0.93). Correlations between BUA and BMD were also significant at p<0.001, but correlation coefficients were lower (R2=0.61-0.75). Residual errors for the estimation of BMD were 8%-10% for SOS as predictor, and 14%-16% for BUA as predictor. The residual error of 8 to 10% for the estimation of BMD from SOS is comparable to variabilities among different DXA femur subregions and accuracy errors of femoral DXA measurements caused by the impact of soft tissue. It is substantially smaller than the errors of 13% for the estimation of total femur BMD from spine BMD, 14% for the estimation of total femur BMD from calcaneus SOS or 16% for the estimation of ash weight from DXA. The results of the study show that SOS is able to predict total BMD with adequate accuracy. If femoral BMD could be obtained in vivo with comparable accuracy, femoral QUS would be suited for the assessment of bone status at one of the main osteoporotic fracture sites.     

Ultrasound bone densitometry of Os calcis in elderly Japanese women with hip fracture

We evaluated 138 elderly patients (mean age 79 years) within 2 weeks after hip fracture (67 cervical and 71 trochanteric) using an Achilles ultrasound bone densitometer (Lunar Corporation, Madison, WI). The ultrasound variables of speed of sound (SOS in m/second), broadband ultrasound attenuation (BUA in dB/MHz), and stiffness (%) index were measured on the os calcis. Ultrasound densitometry also was done on 563 normal postmenopausal women to assess normal age changes. An elderly subgroup (n = 138) served as age-matched controls for the hip fracture group. Further subgroups of 33 patients and 33 controls were compared for lumbar spine and femoral neck BMD. There were no statistically significant differences between the hip fracture group and age-matched controls in height and weight, but each ultrasound variable was significantly lower for the hip fracture group (P < 0.0001). For the hip fracture group, SOS was 1470 ± 19 m/second, BUA was 84.3 ± 8.4 dB/MHz, and the stiffness index was 47.8 ± 9.2%, whereas for the age-matched controls, SOS was 1486 ± 27 m/second, BUA was 94.0 ± 11.4 dB/MHz, and the stiffness index was 59.1 ± 12.5%. There were no significant differences between cervical and trochanteric hip fracture groups. Logistic regression analysis showed that a change of the ultrasound values by 1 standard deviation (SD) changed the odds ratio for SOS, BUA, and stiffness index by 2.51, 3.24, and 3.60, respectively. Ultrasound variables, particularly stiffness, were good indicators of hip fracture risk. Received: 7 June 1995 / Accepted: 14 June 1996     

Age, gender, and fragility fractures are associated with differences in quantitative ultrasound independent of bone mineral density

Bone strength is determined by bone mineral density (BMD) and bone structure. Dual-energy X-ray absorptiometry (DXA) measures BMD. Whether quantitative ultrasound (qUS) measures a property of bone distinct from BMD is uncertain. To evaluate this, DXA and qUS were measured in 58 fracture patients and 428 controls. To study the independent effects of age and gender on qUS measurements and control for BMD by study design rather than statistical methods, subgroups from the normative database were created and intentionally matched by the same femoral neck (FN) BMD. Speed of sound (SOS; m/sec), broadband ultrasound attenuation (BUA; dB/MHz), and stiffness index (SI) were then compared in individuals matched by FN BMD but differing in age, gender, and presence or absence of fractures. The results are presented as percentage difference (mean +/- SD). Elderly women with the same FN BMD as young women had 1 +/- 2% lower SOS (p < 0.05), 8 +/- 15% lower SI (p < 0.05), and 4 +/- 9% lower BUA (p = 0.07). Elderly women with the same FN BMD as elderly men had 5 +/- 9% lower BUA (p < 0.05). Elderly men with the same FN BMD as young men had 1 +/- 2% lower SOS (p = 0.1), 5 +/- 14% lower SI (p = 0.2), and 1 +/- 9% lower BUA (n.s.). Young women with the same FN BMD as young men had 2 +/- 7% lower BUA (n.s.). Women with fragility fractures had 8 +/- 11% lower BUA (p < 0.001) and 13 +/- 22% lower SI (p < 0.01) than controls with no fractures matched by FN BMD, age, and gender. Men with fragility fractures had 13 +/- 12% lower BUA (p < 0.01) and 16 +/- 19% lower SI (p < 0.05) than controls with no fractures matched by FN BMD, age, and gender. Despite comparable femoral neck BMD, qUS measurements differed according to age, gender, and fracture status, suggesting that qUS may provide additional information independent of femoral neck BMD, such as differences in connectivity or other properties yet to be identified.     

Ultrasound bone densitometry of the os calcis in Japanese women

The velocity (SOS), attenuation slope (BUA) and stiffness index in the os calcis were measured using the Achilles ultrasound bone densitometer (Lunar, Madison, WI). We evaluated the basic attributes of this ultrasound bone densitometer, and showed the age-related changes in ultrasound values in normal Japanese women. The precision was measured in vivo on ten occasions over a 2-week period in 5 subjects. The short-term precision errors (CVs) in vivo were 0.6% for stiffness index, 0.3% for SOS and 1.0% for BUA. Spine, femur neck and total body BMD using dual X-ray absorptiometry (DXA) were highly correlated with stiffness index (r=0.80, 0.77 and 0.78, respectively) in 194 subjects. Ultrasound values for patients with osteoporosis were significantly lower than those for the normal controls. TheZ-score compared with young normals was significantly higher for spine bone mineral density (–4.4) than for stiffness index (–3.5); BUA and SOS gave significantly lowerZ-scores –2.9 and –3.0, respectively). Ultrasound values were also lower compared with age-matched normal controls. TheZ-score for stiffness index (–2.1) was significantly superior to that for either SOS or BUA (–1.5). Age-related change in ultrasound values was evaluated in 842 normal women. There was a decline in stiffness index of about 24% from the values in young adulthood to those of women in their seventies, about 75% of which occurred from age 44–49 years onward. These findings seem to indicate that the menopause affected the change in ultrasound values. In conclusion, ultrasound bone densitometry may not be as useful as DXA of the spine for screening for osteoporosis, since theZ-score for DXA is excellent. However, ultrasound bone densitometry appears potentially to be applicable to problems in the diagnosis and management of osteoporosis when used in association with DXA.     

Sex and age patterns of quantitative ultrasound densitometry of the calcaneus in normal japanese subjects

The speed of sound (SOS), broadband ultrasound attenuation (BUA), and the stiffness index (stiffness), which was derived from SOS and BUA, were measured on the calcaneus using the Achilles ultrasound densitometer (Lunar) in normal Japanese woman (n = 473) and men (n = 218). Sex differences and age-related changes in these variables were investigated. In addition, the bone mineral density (BMD) of the lumbar vertebrae measured by dual X-ray absorptiometry (QDR-2000, Hologic) was compared with SOS, BUA, and stiffness. There were some decreases of ultrasound variables in both young adult men and women. BMD values were similar in young adults of both sexes. BMD was relatively stable in women from 20 to 49 years, then decreased at about 1.5%/year. Ultrasound variables were higher in males than females at all ages, and they decreased from age 20 onward in both sexes with an annual loss of about 0.6%. Age-related changes in SOS, BUA, and stiffness were different from those in BMD in normal Japanese subjects. The correlations between BMD and SOS and BUA and stiffness were higher in women (r = 0.51–0.64) than in men (r = 0.43–0.49).     

Bone properties as estimated by mineral density, ultrasound attenuation, and velocity

Quantitative ultrasound (QUS) analysis of bone has been suggested to have a level of performance equal to dual-energy X-ray absorptiometry (DXA) for the assessment of fracture risk. In this study, QUS and DXA measurements were conducted on bovine trabecular bone in vitro using commercially available clinical instruments. The samples were then mechanically tested to obtain Young’s modulus and ultimate strength. In addition, QUS and DXA parameters of the human calcaneus (n = 34) were measured in vivo. The measurements revealed a significant effect of bovine bone size on broadband ultrasound attenuation (BUA) and speed of sound (SOS) in vitro. By normalizing the DXA and QUS results with bone thickness we could systematically improve their ability to predict bone strength. However, in bovine trabecular bone, BUA showed no significant linear correlation with either bone mineral density (BMD), Young’s modulus, or ultimate strength. This finding may be typical of only high-density and low-porosity bovine bone. We significantly improved prediction of ultimate strength by combining density and ultrasound velocity results as compared with assessments of volumetric BMD_vol (p < 0.05) or SOS (p < 0.001) alone. However, the improvement was not significant if BMD_vol, instead of wet density, was used. Altogether, 88% of the variation in the ultimate strength of bovine bone could be explained by combined density and ultrasound velocity. In vivo, SOS showed a weak negative correlation with heel width (r = −0.350). The in vivo measurements also showed a close correlation for BUA with BMD in the human calcaneus. This suggests that BUA is more suitable for quantitative analysis of low-density trabecular bone.     

A Comparison of the Longitudinal Changes in Quantitative Ultrasound with Dual-Energy X-ray Absorptiometry: The Four-Year Effects of Hormone Replacement Therapy

Quantitative ultrasound (QUS) has been proposed as a tool which can measure both the quantitative and qualitative aspects of bone tissue and can predict the future risk of osteoporotic fractures. However, the usefulness of QUS in long-term monitoring has yet to be defined. We studied a group of early postmenopausal women over a 4-year period. Thirty subjects were allocated to hormone replacement therapy and 30 selected as controls matched for age, years past the menopause (YPM) and bone mineral density (BMD) at the anteroposterior spine (AP spine). The mean age of the subjects was 52.4 years (SD 3.9 years), mean YPM 4.0 years (SD 3.2) and all subjects had a BMD T-score above −2.5 SD (number of standard units related to the young normal mean population). BMD was measured at baseline and annually by dual-energy X-ray absorptiometry (DXA) at the AP spine and total hip, and QUS carried out at the calcaneus, measuring broadband ultrasound attenuation (BUA), speed of sound (SOS) and Stiffness. Mean percentage changes from baseline were assessed at 2 and 4 years. The overall treatment effect (defined as the difference in percentage change between the two groups) was: AP spine BMD, 11.4%; total hip BMD, 7.4%; BUA, 6.4%; SOS, 1.1%; and Stiffness, 10.4% (p<0.01). To compare the long-term precision of the two techniques we calculated the Standardized Precision, which for QUS was approximately 2–3 times that of DXA, for a given rate of change. The ability of each site to monitor response to treatment was assessed by calculating the Treatment Response Index (Treatment Effect/Standardized Precision), which was: AP spine BMD, 10.4; total hip BMD, 3.9; BUA, 3.1; SOS, 0.3; and Stiffness, 4.2. This was then normalized for AP spine BMD (to compare the role of QUS against the current standard, AP Spine BMD), which was: total hip BMD, 0.38; BUA, 0.30; Stiffness, 0.40 (p<0.01); and SOS, 0.03 (NS). In summary, QUS parameters in the early menopause showed a similar rate of decline as AP spine BMD and total hip BMD measured by DXA. Hormone replacement therapy results in bone gain at the AP spine and total hip, and prevents loss in BUA and SOS measured by QUS at the calcaneus. QUS has a potential role in long-term monitoring, although presently the time period to follow individual subjects remains 2–3 times that for DXA, for a given rate of change. Anteroposterior spine remains the current optimal DXA monitoring site due to its greater rate of change and better long-term precision. Received: 20 January 1999 / Accepted: 14 June 1999     

Age-related changes in os calcis ultrasonic indices: A 2-year prospective study

We performed repeated ultrasound measurements approximately 2 years apart (average 23 months ±3 months) on the os calcis of 113 healthy postmeno-pausal women recruited from two large prospective cohort studies named OFELY and EPIDOS. Group A (from OFELY) consisted of 88 women aged 52–72 (63±5) years, randomly selected from a large insurance company, and group B (from EPIDOS) consisted of 25 women aged 75–88 (80±4) years, randomly selected from the voting lists. We obtained broadband ultrasonic attenuation (BUA) and speed of sound (SOS) measurements, as well as the Stiffness index, with a Lunar Achilles ultrasound machine. We performed dual energy X-ray absorptiometry (DXA) measurements of femoral neck bone mineral density (neck BMD) with a Hologic QDR 2000 for group A and with a Lunar DPX Plus for group B. The decrease that we observed over 2 years was on average ±1 SD: –1.01±4.6 dB/MHz (p=0.02) for BUA (which is approximately equal to the long-term precision error in vitro), –11.3±9.2 m/s (p=0.0001) for SOS (approximately 5 times the precision error), –3.8±4.2 %YA (p=0.0001) for Stiffness (2.5 times the precision error) and –0.01±0.03 g/cm2 (p=0.0001) for neck BMD (approximately equal to the precision error). In terms of percentage change this represents: –1.0%±4.3% for BUA, –0.8%±0.6% for SOS and –1.85%±4.4% for neck BMD. At the individual level, most SOS and Stiffness values were consistent with a decrease, whereas BUA and neck BMD values were spread out above and below the zero line of no change. The decreases in SOS and Stiffness were significantly larger in the early postmenopause (20 years since menopause [YSM]) than in the late postmenopause (>20 YSM). We observed a similar trend for BUA and BMD but this did not reach statistical significance. We found a weak but significant correlation between changes in ultrasound variables and changes in neck BMD. However, the 2-year changes observed in SOS were not significantly correlated with changes in BUA. This study suggests that the heel ultrasound measurements of SOS and Stiffness are valuable indices of postmenopausal bone loss, and could be used for follow-up in therapeutic trials.     

Dual X-ray Absorptiometry and Bone Ultrasonography in Patients with Rett Syndrome

This study evaluated bone status and bone turnover in 82 females (ages 2-21 years) with the Rett Syndrome (RS) and 82 age-matched controls. Bone mineral density (BMD) by dual X-ray absorptiometry (DXA) at the ultradistal and proximal radius and ultrasonographic (QUS) parameters at the calcaneus [speed of sound(SOS), broadband ultrasound attenuation(BUA), and stiffness] and at the phalanxes (amplitude dependent speed of sound: AD-SOS) were measured. We also measured serum calcium, phosphate, 25-hydroxyvitamin D, and biochemical markers of bone turnover. DXA and QUS parameters were significantly lower in patients with RS compared with controls and, among RS alone, in those treated with anticonvulsants and in those who are nonambulatory. Ambulatory RS patients showed QUS and DXA parameters significantly greater than nonambulatory patients but significantly lower than controls. Patients with RS treated with anticonvulsants presented QUS and DXA parameters lower than those of other RS. In RS patients, walking significantly influences BMD-UD, BMD-P, SOS. BUA. and Stiffness. Serum 25-hydroxyvitamin D was significantly lower in RS than in controls. These results suggest that ambulatory status, to a major extent, and anticonvulsant therapy certainly play an important role in the reduction of bone mass and bone quality, but they cannot completely explain the altered bone status. Whatever the cause, girls with RS present abnormal bone status with an increase in the risk of fracture.     

Relationship Among MRTA, DXA, and QUS Revisited

Inexpensive, commercially produced devices that directly measure bone strength in vivo are not currently available. Mechanical response tissue analysis (MRTA), a unique prototype device, is an in vivo vibrational test that measures transverse bending stiffness (a measure of whole bone strength expressed as the product of estimated Young's modulus of elasticity and cross-sectional moment of inertia, EI, Nm2) at ulna midshaft. We compared speed of sound (SOS; [m/s]) in ulna cortical bone using a commercially available axial transmission quantitative ultrasound (QUS) device with EI using MRTA. Dual-energy X-ray absorptiometry (DXA) was used to provide an estimate of ulna size (cm2), bone mineral content (BMC; [g/cm]) and areal bone mineral density (BMD; [g/cm2]). The objective of the study was to determine if ulna SOS--alone or in combination with BMD from DXA--was correlated with ulna EI, thus becoming a surrogate measure of transverse bending stiffness, and thus whole bone strength. Data were collected from 138 female volunteers (18-86 yr). EI and SOS were significantly correlated, r = +0.218, p = 0.01, but r2 was very low, 4.8%. SOS and total ulna BMD were combined to estimate elastic modulus, which correlated with EI, r = +0.377, p < 0.0001; however, the correlation was not significantly better than with SOS alone. We conclude that axial transmission QUS is not a strong surrogate in vivo technique for estimating transverse bending stiffness.