The relationship between bone mineral density and ultrasound in postmenopausal and osteoporotic women

QUS characteristics in Normal Population: a Mini Review and our experience

Objectives

Quantitative ultrasound (QUS) is a bone densitometry method that is less expensive and more portable than DXA. It is also noninvasive. QUS parameters include speed of sound (SOS), broad band ultrasound attenuation (BUA), and stiffness index (SI). This study defined normal values of QUS parameters in Iranian men and women.

Methods

QUS of heels measured in 258 Iranian men and women, aged 20-76 y/o. They were participants of Iranian Multicenter Osteoporosis study (IMOS), selected by randomized sampling. QUS device was an Achilles+ (GE-Lunar) device.

Results

Percentiles of SI (2.5%, 50%, and 97.5%) determined. We found a good agreement between the Iranian reference values and western reference (used by device) value in defining normal and osteoporotic people (κ = 0.875).

Conclusion

Results from this study suggest that QUS of the heel may be a good method for diagnosis of low bone mass in different regions.

Quantitative Ultrasound of Phalanx in Primary and Secondary Osteoporosis: Mini-review and Practical Experience

Objective:

Dual x-ray absorptiometry (DXA) is gold standard of bone densitometry, but quantitative ultrasound (QUS) of bone is less expensive and portable. This study was designed to assess its usefulness in secondary osteoporosis diagnosis.

Materials and Methods:

There were 200 secondary osteoporosis cases (rheumatoid arthritis, hemodialysis, kidney transplant patients, and levothyroxine users) and of those, their phalanx QUS results were compared with normal controls. Also, the QUS and DXA results were compared to find any correlation of these methods for diagnosing osteoporosis.

Results:

There was not significantly different results compared with normal controls, except for those of hemodialysis patients ( P = .00). Also, the comparison of QUS with DXA results showed no significant correlation except in hemodialysis patients, in both spinal and femoral regions ( P = .023 and .21, respectively), as well as the levothyroxine group’s spinal region ( P = .005).

Conclusion:

These results suggest that QUS of phalanx may be useful in screening secondary osteoporosis but for establishment of diagnosis, DXA measurements are still needed.

A Cross-Sectional Study of the Association between Autoantibodies and Qualitative Ultrasound Index of Bone in an Elderly Sample without Clinical Autoimmune Disease

Bone loss is characteristic of the ageing process and a common complication of many autoimmune diseases. Research has highlighted a potential role of autoantibodies in pathologic bone loss. The confounding effects of immunomodulatory drugs make it difficult to establish the contribution of autoantibodies amongst autoimmune disease sufferers. We attempted to examine the relationship between autoantibodies and bone mass in a population of 2812 elderly participants without clinical autoimmune disease. Serum samples were assayed for a panel of autoantibodies (anti-nuclear, extractable nuclear antigen, anti-neutrophil cytoplasmic, thyroid peroxidase, tissue transglutaminase, anti-cardiolipin, rheumatoid factor, and cyclic citrullinated peptide). Bone mass was measured using quantitative ultrasound (QUS) of the calcaneus. The relationship between each autoantibody and bone mass was determined using linear regression models. Anti-nuclear autoantibodies were the most prevalent, positive in approximately 11%, and borderline in roughly 23% of our sample. They were also the only autoantibody observed to be significantly associated with QUS index in the univariate analysis (n = 1628; r = -0.20; 95% CI: -0.40-0.00; p = 0.046). However, statistical significance was lost after adjustment for various other potential confounders. None of the other autoantibodies was associated with QUS index in either univariate or multivariate analysis. We are limited by the cross-sectional nature of the study and the low prevalence of autoantibodies in our nonclinical sample.

Defining cut-off values for the diagnosis of osteoporosis in postmenopausal women by quantitative ultrasonography of the phalanx

AIM

Quantitative ultrasound (QUS) of the phalanx is a non-invasive, inexpensive and portable method for bone assessment. We determined a cut off point for it in the diagnosis of osteoporosis.

METHODS

In 180 postmenopausal women, dual-energy X-ray absorptiometry (DEXA) of the spine and femur and QUS of the phalanx were performed. Then, the optimum cut-off point for QUS was determined.

RESULTS

Osteoporosis was found in 28.8% of women by DEXA (18.3% in L2-L4, 3.9-7.8% in different regions of the femur) and in 28.9% by QUS. Agreement of the methods (kappa value) was 0.317 for spine and 0.036-0.068 for femoral regions. Using receiver-operating characteristic (ROC) curves, we found T-score of -2.0 as the optimum cut-off point of QUS in diagnosing osteoporosis in the spine (sensitivity and specificity were 78.8% and 55.9%, respectively). We did not find a cut-off point for femoral regions because the 95% confidence interval of the area under the ROC curve contained the diagonal line (p = 0.150, 0.179 and 0.05 for femoral neck, trochanter and total femur, respectively). We defined -2.5 as the other T-score cut-off point under these different conditions; more specificity is needed.

CONCLUSION

Agreement was weak to moderate between the two methods. Thus QUS of the phalanx is not a good replacement for DEXA in defining osteoporosis, but it may be used as a screening method.

Hip fracture discrimination by the Achilles Insight QUS imaging device

The importance of osteoporosis as a major health problem is well recognized. Its major clinical manifestation is low energy fractures. Considerable effort has been directed towards search of noninvasive methods for assessing osteoporotic fracture risk. The aim of this study was to evaluate the ability of quantitative ultrasound (QUS) variables measured by a new heel QUS imaging device to discriminate between postmenopausal women with and without hip fracture. The subjects included 30 postmenopausal female patients with hip fracture and 30 age-matched healthy women. Measurements were acquired using the Achilles Insight QUS imaging device. Bone mineral density (BMD) measurements were carried out using the Lunar Prodigy DXA scanner. Achilles Insight provides images of the heel bone and measures broadband ultrasound attenuation (BUA) and speed of sound (SOS) values in a circular region of interest. A third QUS variable, the stiffness index (SI) was also determined. The short-term precision for healthy subjects was 2.05%, 0.17% and 1.91% for BUA, SOS and SI, respectively. Corresponding values for patients with fractures were 1.80%, 0.16% and 2.04%. All QUS variables measured using the Achilles Insight were significant discriminators of hip fractures (area under ROC curve=0.77, 0.74 and 0.77 for BUA, SOS and SI, respectively). BMD measurements of the hip had the greatest discriminatory ability (area under ROC curve=0.88). Statistically significant differences were found between the area under the ROC curve of BMD and the corresponding curves of the QUS variables (P<0.05 for each of the three comparisons). QUS variables measured by Achilles Insight can be expected to be useful as indicators of the risk of hip fracture in postmenopausal women.

Identifying osteoporosis in a primary care setting with quantitative ultrasound: relationship to anthropometric and lifestyle factors

Dual-energy X-ray absorptiometry (DXA), the "gold standard" for diagnosis of osteoporosis, is not recommended for population screening, and thus quantitative ultrasound (QUS) of the calcaneus is gaining popularity. The aim of the present study was to evaluate the relationship between QUS values and anthropometric and lifestyle factors, and to assess the diagnostic performance of QUS in predicting DXA-defined osteoporosis. Eight hundred and thirty-two women and 87 men aged 40-88 years were included in the study. Anthropometric measurements, the questionnaire, and QUS and DXA measurements were performed by trained physicians. Both QUS and DXA T-scores were lower for women than for men. Postmenopausal women had significantly lower QUS T-scores compared to premenopausal women (P < 0.001). Age over 50, female sex, sedentary lifestyle, fracture history, presence of chronic disease, and > or =5 years since menopause were associated with QUS T-scores lower than -1.00 by multivariate analysis. Low QUS T-scores were related to lack of direct sun exposure, high parity, fair skin color, and no education by univariate analysis (P < 0.005). A weak correlation was found between calcaneal QUS and DXA T-scores at lumbar spine (r = 0.310, P < 0.001) and femoral neck (r = 0.288, P < 0.001). The sensitivity and specificity of the QUS test were 73.7% and 57.4%, respectively, regarding the identification of osteoporotic patients. Lower QUS T-scores were associated with several osteoporotic risk factors, and the sensitivity and specificity of QUS for predicting DXA-defined osteoporosis were at optimum values at ages between 50 and 59 years. We conclude that, even though the accuracy of QUS for predicting DXA-defined osteoporosis is not remarkably high, it can be applied to identify subjects at risk in this age group in developing countries and rural districts who should be the focus of fracture prevention.

Quantitative ultrasound is better correlated with bone mineral density and biochemical bone markers in elderly women

The association between quantitative ultrasound (QUS) and bone turnover in postmenopausal women of different ages is an area of continuous investigation. The aim of this study was to investigate the relationship of ultrasound parameters [broadband ultrasound attenuation (BUA) and speed of sound (SOS)] to bone mineral density (BMD) and biochemical markers of bone turnover in three age groups of postmenopausal women. One hundred and twenty-three postmenopausal Caucasian women were divided into three groups according to their age: group A, range 44-54 years, mean age (+/-SD) 48.3 +/- 2.3; group B, range 55-65 years, mean age 59.4 +/- 2.1; and group C, range 66-77 years, mean age 68.2 +/- 3.1. Ultrasound parameters were measured by the DTU-one imaging ultrasonometer in the calcaneus. BMD was assessed by dual-energy X-ray absorptiometry (DEXA) at the lumbar spine, femoral neck, and trochanter. Bone turnover was assessed by serum bone-specific alkaline phosphatase (BAP), urinary excretion of free deoxypyridinoline, N-telopeptides (NTX), and C-telopeptide breakdown products of type I collagen (CTX). QUS and BMD were significantly correlated in all sites, except hip BMD in group A. The most significant correlation was observed between BUA and femoral neck BMD in group C (r = 0.626, p < 0.01). BUA correlated significantly with BAP, NTX, and CTX (r = -0.434, -0.511, -0.478, respectively; p < 0.01), and SOS with BAP and NTX (r = -0.351 and -0.356, respectively; p < 0.05) only in group C. In groups A and B, ultrasound parameters did not correlate significantly to biochemical markers. Ultrasound parameters were better correlated to hip BMD and to biochemical markers of bone turnover in elderly postmenopausal women. These ultrasound measurements could be used as a screening test for bone status, either in nonambulatory third aged women or in those living in rural areas where attending medical centers with DEXA equipment and biochemical laboratories is difficult.

In vitro speed of sound measurement at intact human femur specimens

Quantitative ultrasound has been recognized as a useful tool for fracture risk prediction. Current measurement techniques are limited to peripheral skeletal sites. Our objective was to demonstrate the in vitro feasibility of ultrasonic velocity measurements on human proximal femur and to investigate the relationship between velocity and bone mineral density (BMD). Sound velocity images were computed from 2-D scans performed on 38 excised human femurs in transmission at 0.5 MHz. Different regions-of-interest were investigated. Dual x-ray absorptiometry scans have been achieved for BMD measurements in site-matched regions. Our study demonstrates the feasibility of ultrasonic velocity measurements at the hip with reasonable precision (coefficient of variation of 0.3%). The best prediction of BMD was reached in the intertrochanter region (r(2) = 0.91, p < 10(-4)), with a residual error of 0.06 g/cm(2) (10%). Because BMD measured at the femur is the best predictor of hip fracture risk, the highly significant correlation and small residual error found in this study suggest that speed of sound measurement at the femur might be a good candidate for hip fracture risk prediction.

In vitro ultrasound measurement at the human femur

Measurements of broadband ultrasonic attenuation (BUA) represent an established means of skeletal status assessment in osteoporosis. Today, the skeletal site that is the most widely used clinically is the calcaneus (heel bone). However, we hypothesized that fracture risk predictions could be improved if ultrasound measurements were performed directly at the main site of fracture, e.g., the proximal femur. The goal of this paper is to demonstrate in vitro the feasibility of quantitative ultra sound (QUS) imaging at the upper part of fee femur, and to investigate the relationships of BUA to bone mineral density (BMD). Forty-four excise human femurs were measured in transmission with a pair of focused 0.5-MHz central frequency transducers. Two-dimensional scans were performed, and the radio frequency (rf) signals were recorded at each measurement point. A data acceptance criterion for region of interest (ROI) selection was established based on the linearity of the frequency-dependent attenuation. Five measurements with repositioning were performed on each sample to determine the reproducibility. Dual energy x-ray absorptiometry (DXA) scans have been performed on the samples for BMD measurements: Three ROIs were selected in the specimens: greater, trochanter intertrochanteric, and femoral neck regions. Coefficient of variations were in the range 1.6% to 2.5%. The determination coefficients (r(2)) between BUA and BMD in site-matched ROIs were 0.81, 0.78, and 0.73, respectively, for the greater trochanteric, intertrochanteric, and femoral neck regions. Our results are consistent with data previously shown at the calcaneus and demonstrate the feasibility of QUS measurements at the femur in vitro, with reasonable reproducibility.

Use of quantitative ultrasound of the hand phalanges in the diagnosis of two different osteoporotic syndromes: Cushing's syndrome and postmenopausal osteoporosis

The aim of this study was to assess the ability of the quantitative ultrasound of the hand phalanges to detect different types of osteoporosis resulting from different pathogenetic mechanisms. For this purpose, postmenopausal and glucocorticoid-induced osteoporosis was studied. Thirteen female patients with Cushing's syndrome (CS) resulting from pituitary-dependent bilateral adrenal hyperplasia (10 patients) and from adrenal adenoma (3 patients), and 32 postmenopausal osteoporotic (OP) women, were examined. The two groups of patients were comparable for body mass index (BMI), but CS patients were significantly younger than OP ones (CS 44.5+/-11.6; OP: 73.9+/-3.6). All the patients had femoral neck bone mineral density (BMD) T-score less than -2.0. Cushing patients had a femoral neck BMD similar to that of OP patients (CS: 603+/-66 mg/cm2; OP: 628+/-69 mg/cm2; p=0.19). In contrast, amplitude-dependent speed of sound (AD-SoS) was significantly higher in CS patients than in OP patients (CS: 1997+/-91 m/s; OP: 1707+/-114 m/s; p<0.0001). By adjusting DXA and ultrasound parameters according to age, femoral neck BMD was significantly lower in CS patients and AD-SoS remained significantly higher than in OP patients. These findings indicate that these two different kinds of osteoporosis can be distinguished by ultrasonography and that ultrasound parameters alone cannot be used for evaluating skeletal status in CS patients.

Bone mineral density, ultrasound velocity, and broadband attenuation predict mechanical properties of trabecular bone differently

Measurement of areal bone mineral density (BMD(areal)), broadband ultrasound (US) attenuation (BUA), and speed-of-sound (SOS) are widely used ways to perform clinical assessment of bone quality. In this study, bovine (n = 37) and human (n = 32) trabecular bone was investigated in vitro and in vivo to reveal relationships between mechanical properties, mineral density, and US parameters BUA and SOS. To fulfill these aims, clinical US and dual-energy X-ray absorptiometry (DXA) techniques, as well as dynamic and destructive mechanical testing, were utilized. BUA correlated positively and linearly with BMD(areal) only in human calcaneus of low or moderate density (r = 0.849, n = 32, p < 0.01). When calcaneal areas with high BMD(areal) were included in the analysis, however, the in vivo study revealed that the BUA-BMD(areal) relationship could be described by a second-order polynomial fit (r(2) = 0.618, n = 408). In high-density human or bovine bone, the BUA-bone density relationship was negative. In the in vitro assessment, BUA correlated linearly and negatively with volumetric BMD (BMD(vol)) (r = -0.540, n = 29, p < 0.01) and with storage modulus, as measured at 1 Hz (r = -0.505, n = 28, p < 0.01). A weak positive correlation was found between BUA and mechanical loss tangent (r = 0.322, n = 28, p < 0.1). SOS correlated strongly positively with BMD(vol) (r = 0.888, n = 29, p < 0.01), as well with storage modulus (r = 0.649, n = 28, p < 0.01). In contrast, SOS correlated negatively with loss tangent (r = -0.417, n = 28, p < 0.05). When tested dynamically in the frequency range of 0.01-22.7 Hz, bovine trabecular bone was only slightly viscoelastic. In summary, the most accurate parameters for measuring storage modulus and strength of bovine trabecular bone were SOS and BMD(vol), respectively. BUA failed to predict the mechanical properties of high-density trabecular bone. In vivo mapping of the calcaneus revealed the importance of standardized and reproducible localization of the measurement site for the validity of BUA values.

Potential roles for quantitative ultrasound in the management of osteoporosis

OBJECTIVE

To assess the validity of four models for the role of quantitative ultrasound (QUS) in the management of osteoporosis.

DESIGN

Cross-sectional survey and review of literature.

SETTINGS

Nuclear medicine departments of three teaching hospitals in Sydney.

SUBJECTS

1000 women aged 22 to 88 years (mean, 59 years) referred for assessment of osteoporotic fracture risk.

MAIN OUTCOME MEASURES

BMD categories as defined by dual-energy x-ray absorptiometry (DEXA) of the lumbar spine and proximal femur, and QUS category as defined by calcaneal ultrasound stiffness; prevalence of DEXA-defined osteoporosis in the different QUS categories.

RESULTS

In women with QUS Achilles stiffness < or = 70 the prevalence of axial osteoporosis was 51%, whereas in the group with stiffness > 70 the prevalence of axial osteoporosis was 8%. In women 65 years and over the corresponding values were 59% and 17%.

CONCLUSIONS

Of the four possible models for QUS, the use of QUS for the estimation of BMD, or in a "standalone" model, can not be recommended at the current time. The model of QUS as a "prescreening" modality may be acceptable assuming adequate education of clinicians and patients of its limitations, particularly the risk of false negatives. The model of QUS as one factor in a composite risk factor assessment of patients is promising but more data are required.

Quantitative ultrasound in postmenopausal osteoporosis

Ultrasound has been proposed as a low-cost, radiation-free method for osteoporosis assessment in postmenopausal women. Large prospective studies have shown that ultrasound parameters can be used for fracture risk estimate in this population, providing that adequate quality control is performed. The places of both ultrasound and the current gold standard method for bone assessment, dual energy x-ray absorptiometry, are still to be determined. Further studies are needed on the diagnosis of osteoporosis using ultrasound, because current diagnostic thresholds, designed by the World Health Organization, do not apply to this-new technology. Monitoring of skeletal changes and treatment effects by ultrasound cannot be recommended.

Speed of sound, bone mineral density and bone strength in oophorectomized rats

BACKGROUND

The aim of this study was to determine the sensitivity of bone mineral density (BMD), ultrasounds (SOS) and resistance to torsion (T) to detect experimental osteopenia induced in rats 3 and 6 months after ooforectomy.

MATERIALS AND METHODS

Seventy-four rats were used, divided into four groups, ooforectomized rats analysed 3 and 6 months after the operation and their respective control groups, in which BMD (Hologic QDR 1000 S/N 277), SOS (DBM Sonic 1200) and T (adapted test machine) were determined in the right femur.

RESULTS

The results of the three techniques distinguished the ooforectomized groups from the controls, both 3 and 6 months after the ooforectomy, obtaining more significant differences with BMD (P = 0.0006, P = 0. 001, respectively) than SOS and T, where a significance of only P = 0.05 was obtained. In the correlation study among the three techniques, a significant correlation was observed between BMD and SOS (r = 0.39, P = 0.0008), as well as between BMD and T (r = 0.31, P = 0.03). However, significance was not observed between the SOS and T tests.

CONCLUSION

In the study of sensitivity and specificity of the techniques used to detect the osteopenia caused by the ooforectomy, by means of calculation of the area under the receiver operation characteristic (ROC) curve, it was proven that although the three techniques distinguished between the two analysed populations, BMD presented an area under the ROC curve that was superior (0.87, 0.85) to that obtained with SOS (0.73, 0.67) and T (0.73, 0.68), both 3 and 6 months after the operation.

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.