Transmenopausal change of trabecular bone density and structural pattern assessed by peripheral quantitative computed tomography in Japanese women

Peripheral quantitative computed tomography: optimization of reproducibility measures of bone density, geometry, and strength at the radius and tibia

The aim of this study was to determine the reproducibility for in vivo measurements at the radius and tibia for trabecular and cortical parameters, bone geometry, and bone strength indices with the peripheral quantitative computed tomography (pQCT) XCT 3000. We performed 3 repeated scans within 2mo at the radius (N=18) and tibia (N=16) on healthy, premenopausal women, aged 22-35 yrs and report precision measures including %coefficient of variation (%CV) and least significant changes (LSCs). For the radius, we studied 2 sections (4% and 33% of total length) and for the tibia, 3 sections (4%, 38%, and 66% of total length). Reproducibility for radius at 33% and tibia at every site was good (%CV ranged from 0.02% to 2.19%). The precision error for the distal 4% radius was, however, higher. The reproducibility at the distal radius improved when we considered only the scans with a change of ± 10mm(2) in the radius total area at this site (%CV from 0.87% to 2.25%). This study showed that, when follow-up measurements are carefully obtained, pQCT yields excellent reproducibility at both the radius and tibia. These precision errors, in conjunction with changes in LSC for the pQCT measures, are useful for research and potential clinical applications.

Relationship of circulating total homocysteine and C-reactive protein to trabecular bone in postmenopausal women

Homocysteine (Hcy) and C-reactive protein (CRP) are novel risk factors for osteoporosis. The purpose of this analysis was to determine the relationship of Hcy and CRP to volumetric trabecular bone, but also to assess their relationship to areal composite bone in healthy postmenopausal women (N=184). We used peripheral quantitative computed tomography to assess volumetric bone at the distal tibia and dual-energy X-ray absorptiometry to assess areal composite bone at the proximal femur and lumbar spine. Multiple regression revealed that 22% of the variability in trabecular bone mineral content (F=9.59, p<or=0.0001) was accounted for by weight (12.4%; p<or=0.0001), hemoglobin (5.5%; p=0.0006), uric acid (4.2%; p=0.003), and blood glucose (1.5%; p=0.07). Multiple regression revealed that 5.4% of the variability in trabecular bone mineral density (F=3.36; p=0.020) was accounted for by hemoglobin (4.2%; p=0.006) and Hcy (1.5%; not significant, p=0.10). Total Hcy and CRP were not significantly related to trabecular bone, perhaps because these were nonosteoporotic women. However, our results suggested a weak but negative relationship between Hcy and trabecular bone. Further investigation is needed to examine the relationship of Hcy as an endogenous bioactive molecule to trabecular bone loss in early postmenopausal women and the response of trabecular bone to dietary intervention.

Quantitative bone ultrasound at phalanges and calcaneus in osteoporotic postmenopausal women: influence of age and measurement site

Phalangeal and calcaneal quantitative ultrasound (QUS) measurements were tested in a postmenopausal osteoporotic population of a wide age range to assess their ability to identify subjects with vertebral fractures in a population of postmenopausal women with osteoporosis. A group of 127 osteoporotic women aged from 50 to 85 y, who had been postmenopausal for at least 5 y, were enrolled. All subjects underwent phalangeal and calcaneal QUS measurements, femoral neck and lumbar spine dual energy X-ray absorptiometry (DXA) measurements and lateral thoracic and lumbar spine radiography. Osteoporosis was defined on the basis of femoral neck or lumbar spine bone mineral density (BMD) T-score lower than -2.5 SD or of the presence of one or more vertebral atraumatic fractures, independently of BMD values. Fifty-two women had one or more vertebral fractures, while the remaining 75 had no evidence of previous fracture. Both QUS techniques were able to discriminate between fractured and nonfractured subjects in the whole group (p < 0.05). When patients aged <70 y (n = 43) and patients aged > or = 70 y (n = 84) were considered separately, phalangeal QUS and lumbar spine BMD were able to discriminate vertebral fractures in the younger group (p < 0.05), whereas calcaneal QUS was able to discriminate vertebral fractures in the older one (p < 0.05). The results of this study raise an issue of the optimal use of different QUS techniques and different skeletal sites in the management of osteoporosis in early or late postmenopausal life.

Differences of bone mass and bone structure in osteopenic rat models caused by spinal cord injury and ovariectomy

Both spinal cord injury and ovariectomy can result in ostepenia in rats. SCI induces more deterioration of cortical geometric structure and trabecular microstructure in the proximal tibial metaphysis than OVX. The proximal tibial metaphysis microstructure significantly correlates with its biomechanical properties.

INTRODUCTION

The purpose of the present study was to compare the effects of spinal cord injury (SCI) and ovariectomy (OVX) on bone gain in young female rats.

METHODS

Thirty young female Sprague-Dawley rats were randomized into three groups: age-matched intact control (CON), OVX and SCI. The tibiae were assessed for DXA and micro-CT analysis, biomechanical testing, the upper tibial epiphyseal plate height, and blood samples for biochemical analysis.

RESULTS

SCI rats showed lower aBMD in the proximal tibiae as compared with OVX rats. Cortical geometric structural parameters of the tibial midshaft in SCI rats were significantly lower than OVX rats. SCI or OVX induced significant changes in all trabecular microstructural parameters in the proximal tibial metaphysis. The trabecular separation (Tb.Sp) and structure mode index (SMI) in SCI rats were significantly higher than in OVX rats. BV/TV explained 84% of the variation of ultimate load of the proximal tibial metaphysis. There was no difference of the upper tibial epiphyseal plate height between SCI and OVX rats. Serum NTX level in SCI rats was significantly higher than in OVX rats.

CONCLUSIONS

SCI induces more deterioration of cortical bone geometric structure and trabecular microstructure in the proximal tibial metaphysis than OVX.

Influence of sex hormone disturbances on the internal structure of the mandible in newborn mice

It has not yet been clarified how sex hormones affect craniofacial bone development immediately after birth. The purpose of this study was to examine the effects of sex hormone deficiency on craniofacial bone development immediately after birth, in terms of the internal structure of the mandible in newborn mice with orchiectomy (ORX) and ovariectomy (OVX). ORX, OVX and a sham-operation were performed on 40 five-day-old C57BL/6J mice. Eight weeks after surgery, each mandible was subjected to histomorphometric analysis of trabecular (Tr) and cortical (Ct) bone mineral density (BMD) by peripheral quantitative computed tomography (pQCT). In the experimental groups, a significant reduction in BMD was found in comparison with the control groups. In histomorphometric analysis, the number of tartrate-resistant acid phosphatase (TRAP)-positive cells in the condyle and the thickness of the condylar cartilage layer was significantly greater in the experimental mice than in the controls. Trabecular bone volume of the condyle measured on azocarmine-aniline blue (AZAN) sections was significantly less in the experimental mice than in the controls. These results indicate that mandibular growth is inhibited by sex hormone disturbances and the relevant internal structures changed. The findings show that sex hormones are one of the key determinants of mandibular growth and development immediately after birth.

Femoral neck trabecular microstructure in ovariectomized ewes treated with calcitonin: MRI microscopic evaluation

Ovariectomy induces deterioration of the trabecular structure in the femoral neck of ewes, as depicted by MR microscopic imaging. This structural deterioration is prevented by salmon calcitonin treatment.

INTRODUCTION

This study evaluated the trabecular (Tb) microarchitecture of an ovariectomy (OVX)-induced osteoporotic model in ewes and determined the effects of salmon calcitonin (sCT), an osteoclast inhibitor, on the Tb structure. This is the first report of OVX-induced changes in the Tb structure in the femoral neck in the ewes and effect of sCT on the microarchitecture.

MATERIALS AND METHODS

Ewes (5-8 years old, n = 28) were equally allocated into sham (Sham), OVX injected with vehicle, or OVX injected with sCT at 50 or 100 IU, three injections per week. They were killed 6 months after OVX. The femoral neck was examined with an MR imager at 9.4 T in axial, coronal, and sagittal planes. An internal calibration procedure as a means of standardizing image analysis was used to adjust the segmentation threshold. Data from all three planes were averaged.

RESULTS AND CONCLUSIONS

Compared with Sham, OVX induced significant changes (p < 0.0125) in the MRI-derived femoral neck Tb structure: Tb bone volume fraction (BV/TV), -18%; Tb number, -20%; Tb separation, +23%; number of free ends, +28%; number of nodes, -39%; number of Tb branches, -23%; mean length of Tb branches, -19%. Compared with OVX, treatment of sCT at 100 IU significantly improved all the Tb structural parameters to the Sham level (p < 0.0001 approximately p = 0.0281), whereas 50 IU significantly increased the Tb number and the mean length of the Tb branches. BV/TV explained 74% of the variation of compressive stress of the trabecular cylinder cores of the femoral neck. Combining all structural parameters in a multivariate regression analysis significantly improved the explanation to 84%, and adding BMD further improved the predictive ability of the model to 92%. We conclude that OVX induces deterioration of the MRI-derived Tb microstructure in the femoral neck of ewes. sCT treatment prevents OVX-induced changes. The femoral neck microarchitecture significantly correlates with its biomechanical properties. Combining microstructural parameters with BMD further improves the prediction of bone biomechanical properties. The effects of sCT on OVX ewes may help explain reduced fracture risk in postmenopausal osteoporotic women treated with sCT.

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.

Effects of physical training on cortical bone at midtibia assessed by peripheral QCT

Effects of long-term exercise on volumetric bone mineral density (vBMD), bone mineral content, bone geometric properties, and the strength indexes of bone were examined in a cross-sectional study of athletes and controls. Tibias of 25 jumpers (13 women), 30 swimmers (15 women), and 25 controls (15 women), aged 18-23 yr, were scanned at midsite by using peripheral quantitative computed tomography. The cortical vBMD of female athletes was lower than that of the controls (2.00 +/- 0.05, 1.90 +/- 0.08, and 1.92 +/- 0.12 g/cm3, respectively, for controls, swimmers, and jumpers). On the other hand, periosteal areas of male jumpers and female athletes were greater than that of controls (460 +/- 50, 483 +/- 46, and 512 +/- 55 mm2, respectively, for male controls, swimmers, and jumpers, and 283 +/- 52, 341 +/- 73, and 378 +/- 75 mm2, respectively, for female controls, swimmers, and jumpers). The endocortical area of female swimmers was greater than that of controls (103 +/- 29, 148 +/- 52, and 135 +/- 54 mm2, respectively, for controls, swimmers, and jumpers). The polar moment of inertia and strength strain index of male jumpers and female athletes were significantly greater than those of controls, except for the difference in strength strain index between male jumpers and controls. We conclude that the improvement of mechanical properties of young adult bone in response to long-term exercise is related to geometric adaptation and not to vBMD.

Regular Tai Chi Chuan exercise may retard bone loss in postmenopausal women: A case-control study

OBJECTIVE

To evaluate the potential benefits of regular Tai Chi Chuan exercise on the weight-bearing bones of postmenopausal women.

DESIGN

Case-control study.

SETTING

University medical school in Hong Kong.

PARTICIPANTS

Postmenopausal women (age range, 50-59y), including 17 self-selected regular Tai Chi Chuan exercisers (TCE) with over 4 years of regular exercise, and 17 age- and gender-matched nonexercising controls (CON).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Bone mineral density (BMD) in the lumbar spine and proximal femur was measured at baseline and at follow-up 12 months later by using dual-energy x-ray absorptiometry (DXA) and in the distal tibia using multislice peripheral quantitative computed tomography (pQCT).

RESULTS

Baseline results showed that the TCE group had significantly higher BMD (10.1%-14.8%, all P<.05) than the CON group in the lumbar spine, proximal femur, and the ultradistal tibia. The follow-up measurements showed generalized bone loss in both groups. Although both DXA and pQCT measurements revealed decelerated rates of bone loss in the TCE group, only the more sensitive pQCT showed significantly reduced rate of bone loss in trabecular BMD of the ultradistal tibia (TCE vs CON: -1.10%+/-1.26% vs -2.18%+/-1.60%, P<.05) and of cortical BMD of the distal tibial diaphysis (TCE vs CON: -0.90%+/-1.36% vs -1.86%+/-0.93%, P<.05).

CONCLUSION

This is the first case-control study to show that regular Tai Chi Chuan exercise may help retard bone loss in the weight-bearing bones of postmenopausal women.

Paradoxical adaptation of mature radius to unilateral use in tennis playing

The positive effects of physical activity on human bone mass have been well documented in many cross-sectional studies comparing athletes with sedentary controls as well as in longitudinal follow-up. By applying peripheral quantitative computed tomography (pQCT), which has the advantage of measuring volumetric bone mineral density (BMD) and the ability to distinguish among trabecular and cortical components, it was demonstrated that cortical BMD of the dominant arm was not greater than that of the nondominant arm. Cortical drift toward the periosteal direction and an increase in cortical thickness resulted in an improvement of mechanical characteristics of the playing arm's midradius. An improvement in the mechanical properties of young adult bone in response to long-term exercise was therefore related to geometric adaptation, but not to an increase in BMD. The manner in which the recruitment and function of bone cells are coordinated differs between the growing and the nongrowing skeleton. In the former, modeling is the dominant mode, and in the latter it is remodeling. In the present study, the side-to-side difference of 92 middle-aged female tennis players who initiated training after bone had matured was analyzed by pQCT. The side-to-side difference detected suggested a paradoxical adaptation of the mature radius to unilateral use during tennis playing, and that tennis playing after bone had matured did not stimulate cortical drift in the periosteal direction, unlike that seen in young subjects. Unexpectedly, the cross-sectional areas (periosteal and endocortical area) of the radius were smaller in the dominant arm than in the nondominant arm in the middle-aged female players. The findings suggest that unilateral use of the arm after the third decade of life suppresses age-related changes in bone geometry.

A comparison of radial peripheral quantitative computed tomography, calcaneal ultrasound, and axial dual energy X-ray absorptiometry measurements in women aged 45-55 yr

Perimenopausal bone loss is considered to affect trabecular bone preferentially. Peripheral quantitative computed tomography (pQCT) quantifies trabecular bone mineral density (BMD) independently at the ultradistal radius. This article examines differences in pQCT BMD between late premenopausal and early postmenopausal women, comparing the differences with calcaneal ultrasound and axial dual energy X-ray absorptiometry measurements. One hundred nineteen normal perimenopausal women aged 45-55 yr who attended a randomized osteoporosis screening program were stratified by menopausal status into premenopausal (PRE: n = 79) and postmenopausal (POST: n = 40) groups. All measurements were lower in the postmenopausal group with the exception of ultrasonic velocity (PRE vs POST: 1397 +/- 53.8 vs 1421 +/- 58.5 m/s, p = 0.037). Total (391.8 +/- 52.9 vs 366.3 +/- 68.6 g/cm(3), p = 0.013) and subcortical (533.6 +/- 59.4 vs 504.3 +/- 79.8 g/cm(3) p = 0.018), but not trabecular (187.5 +/- 38.8 vs 173.2 +/- 46.6 g/cm(3), p = 0. 098) or cortical (561 +/- 53.4 vs 551.2 +/- 66 g/cm(3), p = 0.174), pQCT BMD measurements were significantly lower in the POST group, as were ultrasonic attenuation (79.4 +/- 16 vs 72.3 +/- 18.0 dB/Mz, p = 0.034), DXA spine (1.032 +/-16 vs 0.959 +/- 0.2 g/cm(2), p = 0.003), and all hip (p </= 0.001) measurements. Although body mass index (BMI) was positively and menopausal status and age negatively correlated with most bone mass measurements, adjusting for BMI did not alter the relative deficits in postmenopausal compared with premenopausal women. This study suggests that early postmenopausal bone loss at the radius preferentially affects subcortical, rather than trabecular, bone in the appendicular skeleton, which suggests preferential trabecular bone loss in the axial skeleton.

Trabecular bone mineral and calculated structure of human bone specimens scanned by peripheral quantitative computed tomography: relation to biomechanical properties

The relationship of cortical bone mineral density (BMD), and geometry to bone strength has been well documented. In this study, we used peripheral quantitative computerized tomography (pQCT) to acquire trabecular BMD and high-resolution images of trabeculae from specimens to determine their relationship with biomechanical properties. Fifty-eight human cubic trabecular bone specimens, including 26 from the vertebral bodies, were scanned in water and air. Trabecular structure was quantitated using software developed with Advanced Visual Systems interfaced on a Sun/Sparc Workstation. BMD was also obtained using a whole-body computerized tomography scanner (QCT). Nondestructive testing of the specimens was performed to assess their elastic modulus. QCT and pQCT measurements of BMD of specimens in water were strongly correlated (r2 = 0.95, p < 0.0001), with a slope (0.96) statistically not significantly different from 1. Strong correlations were found between pQCT measurements of specimens in water and in air, for BMD (r2 = 0.96, p < 0.0001), and for apparent trabecular structural parameters (r2 = 0.89-0.93, p < 0.0001). Correlations were moderate between BMD and apparent trabecular structural parameters (r2 = 0.37-0.64, p < 0.0001). Precision as coefficient of variation (CV) and standardized coefficient of variation (SCV) for these measurements was < 5%. For the vertebral specimens, the correlation was higher between elastic modulus and BMD (r2 = 0.76,p < 0.0001) than between elastic modulus and apparent trabecular structural parameters (r2 = 0.58-0.72, p < 0.0001), while the addition of apparent trabecular nodes and branches to BMD in a multivariate regression model significantly increased the correlation with the elastic modulus (r2 = 0.86, p < 0.01). Thus, pQCT can comparably and reproducibly measure trabecular bone mineral in water or air, and trabecular structure can be quantitated from pQCT images. The combination of volumetric BMD with trabecular structural parameters rather than either alone improves the prediction of biomechanical properties. Such a noninvasive approach may be useful for the preclinical study of osteoporosis.

Accuracy of cortical and trabecular bone measurements with peripheral quantitative computed tomography (pQCT)

In order to assess the accuracy of peripheral QCT (Stratec XCT 960) we analysed scans of the European Forearm Phantom and another phantom consisting of K2HPO4 encased in aluminium tubes to simulate cortical walls. Additionally 14 cadaveric forearm specimen scans were compared to CT scans acquired on a GE9800Q. The accuracy for density assessment of the European Forearm Phantom was better than 3%. A small increase in density was observed with increasing thickness of the aluminium wall (10% for each mm). Density measurements within the wall were confounded by limited spatial resolution. For a thickness of less than 4 mm, the density within the wall was underestimated by up to 40%. The measurement of mineral content was not influenced by this effect and showed an accuracy error of less than 6%. The agreement of density measurements on the different CT systems was very strong (R2 > 0.96; RMSE < 6.2%). Our findings suggest that the Stratec pQCT scanner very accurately measures volumetric trabecular and total bone mineral densities at the distal radius while the assessment of cortical density is associated with considerable inaccuracies due to limited spatial resolution.

Clinical evaluation of a high-resolution new peripheral quantitative computerized tomography (pQCT) scanner for the bone densitometry at the lower limbs

Precision, long-term stability, linearity and accuracy of the x-ray peripheral quantitative computerized tomographic (pQCT) bone scanner XCT 3000 (Norland-Stratec Medical Sys.) were evaluated using the European Forearm Phantom (EFP). In vivo measurements were assessed using a standardized procedure at the distal femur and the distal tibia. In the patient-scan mode, the spatial resolution of the system was 1.04 +/- 0.05 lp/mm as measured at the 10% level of the modulation transfer function (MTF). The contrast-detail diagram (CDD) yielded a minimal difference in attenuation coefficient (AC) of 0.07 cm(-1) at an object size of 0.5 mm. The effective dose for humans was calculated to be less than 1.5 microSv per scan. Short-term precision in vivo was expressed as root mean square standard deviation of paired measurements of 20 healthy volunteers (RMSSD = 0.5%). At the distal femur total volumetric density (ToD) and total cross-sectional area (ToA) were found to be less sensitive to positioning errors than at the distal tibia. Structural parameters like the polar cross-sectional moment of inertia (CSMIp) or the polar cross-sectional moment of resistance (CSMRp) showed a good short-term precision at the distal femur (RMSSD = 1.2 and 1.4%). The relation between the two skeletal sites with respect to CSMIp or CSMRp showed a high coefficient of determination (r2 = 0.77 and 0.74).

Volumetric bone mineral density using peripheral quantitative computed tomography in Japanese women

The present study evaluated a commercial device for peripheral quantitative computed tomography (pQCT) and examined the age-related changes in normal Japanese women. The volumetric bone mineral density (vBMD) of the distal radius [integral bone mineral density (BMDI), trabecular bone mineral density (BMDT) and cortical with subcortical bone mineral density (BMDSC)] was measured using pQCT (Norland-Stratec XCT960) in 617 healthy women aged 20-79 years and 75 subjects with osteoporosis aged 60-89 years who exhibited at least one vertebral fracture. The short-term precision errors in vivo (CV, %) were 1.1% for BMDI, 1.1% for BMDT and 1.2% for BMDSC. The correlations between pQCT and dual-energy X-ray absorptiometry measurements (Lunar DPX) of the lumbar spine were r approximately 0.8 (BMDI, BMDT and BMDSC). The maximal mean vBMD values were observed between 20 and 49 years; BMDI, BMDT and BMDSC all showed a linear postmenopausal decline averaging 1.1% per year. The overall decreases in vBMD from the peak values in those 70-79 years were 34%, 32% and 33% in BMDI, BMDT and BMDSC, respectively. The diagnostic sensitivity of osteoporosis was expressed as a T-score. T-scores using pQCT were -3.0 (BMDI), -2.4 (BMDT) and -2.9 (BMDSC). Bone mineral measurement of the distal radius may be useful in the evaluation of age-related bone loss and for the diagnosis of osteoporosis.