Estimates of volumetric bone density from projectional measurements improve the discriminatory capability of dual X-ray absorptiometry

The correlation between osteoporotic vertebrae fracture risk and bone mineral density measured by quantitative computed tomography and dual energy X-ray absorptiometry: a systematic review and meta-analysis

This paper presents a comparison of quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA) in osteoporosis with vertebral fracture and osteoporosis without fracture. It has been proved that the volumetric bone mineral density (vBMD) measured by QCT exhibits a stronger correlation with fracture risk than areal bone mineral density (aBMD) measured by DXA.

PURPOSE

This study aims to systematically evaluate the ability of QCT and DXA to distinguish between osteoporosis with vertebral fracture and osteoporosis without fracture according to vBMD and aBMD.

METHODS

We conducted a primary literature search of the online databases up to 3 July, 2022, in both English and Chinese publications, combining synonyms for "QCT", "DXA" and "osteoporosis". The Newcastle-Ottawa scale (NOS) was employed to evaluate the quality of the selected articles. vBMD obtained through QCT and aBMD obtained through DXA were extracted, and were analyzed by Review Manager 5.4 and RStudio.

RESULTS

Six studies with 610 individuals aged 45 to 90, of which 179 had vertebral fractures, were included in the final analysis. The weighted mean difference (WMD) between osteoporosis with vertebral fracture and osteoporosis without fracture for vBMD was - 27.08 (95% CI  - 31.24 to  - 22.92), while for aBMD was - 0.05 (95% CI - 0.08 to - 0.03).

CONCLUSIONS

Both vBMD detected by QCT and aBMD detected by DXA could discriminate fracture status in the spine, and vBMD performed a stronger correlation with fracture risk.

TRIAL REGISTRATION

PROSPERO 2022 CRD42022349185.

Performance of iCare quantitative computed tomography in bone mineral density assessment of the hip and vertebral bodies in European spine phantom

BACKGROUND

Osteoporosis is a systemic bone disease which can increase the risk of osteoporotic fractures. Dual-energy X-ray absorptiometry (DXA) is considered as the clinical standard for diagnosing osteoporosis by detecting the bone mineral density (BMD) in patients, but it has flaws in distinguishing between calcification and other degenerative diseases, thus leading to inaccurate BMD levels in subjects. Mindways quantitative computed tomography (Mindways QCT) is a classical QCT system. Similar to DXA, Mindways QCT can directly present the density of trabecular bone, vascular or tissue calcification; therefore, it is more accurate and sensitive than DXA and has been widely applied in clinic to evaluate osteoporosis. iCare QCT osteodensitometry was a new phantom-based QCT system, recently developed by iCare Inc. (China). It has been gradually applied in clinic by its superiority of taking 3-dimensional BMD of bone and converting BMD values to T value automatically. This study aimed at evaluating the osteoporosis detection rate of iCare QCT, compared with synchronous Mindways QCT (USA).

METHODS

In this study, 131 patients who underwent hip phantom-based CT scan were included. Bone mineral density (BMD) of the unified region of interests (ROI) defined at the European spine phantom (ESP, German QRM) including L1 (low), L2 (medium), and L3 (high) vertebral bodies was detected for QCT quality control and horizontal calibration. Every ESP scan were taken for 10 times, and the mean BMD values measured by iCare QCT and Mindways QCT were compared. Hip CT scan was conducted with ESP as calibration individually. T-scores gained from iCare QCT and Mindways QCT were analyzed with Pearson correlation test. The detection rates of osteoporosis were compared between iCare QCT and Mindways QCT. The unified region of interests (ROI) was delineated in the QCT software.

RESULTS

The results showed that there was no significant difference between iCare QCT and Mindways QCT in the evaluation of L1, L2, and L3 vertebrae bodies in ESP. A strong correlation between iCare QCT and Mindways QCT in the assessment of hip T-score was found. It was illustrated that iCare QCT had a higher detection rate of osteoporosis with the assessment of hip T-score than Mindways QCT did. In patients < 50 years subgroup, the detection rate of osteoporosis with iCare QCT and Mindways QCT was equal. In patients ≥ 50 years subgroup, the detection rate of osteoporosis with iCare QCT (35/92, 38.0%) was higher than that with Mindways QCT. In female subgroup, the detection rate of osteoporosis with iCare QCT was significantly higher than Mindways QCT. In male subgroup, the detection rate of osteoporosis with iCare QCT was also markedly higher than Mindways QCT. The detection rate of osteoporosis by iCare QCT was higher than Mindways QCT with hip bone assessment. Of course, the results of the present study remain to be further verified by multicenter studies in the future.

Opportunistic Screening Using Low-Dose CT and the Prevalence of Osteoporosis in China: A Nationwide, Multicenter Study

Opportunistic screening for osteoporosis can be performed using low-dose computed tomography (LDCT) imaging obtained for other clinical indications. In this study we explored the CT-derived bone mineral density (BMD) and prevalence of osteoporosis from thoracic LDCT in a large population cohort of Chinese men and women. A total of 69,095 adults (40,733 men and 28,362 women) received a thoracic LDCT scan for the purpose of lung cancer screening between 2018 and 2019, and data were obtained for analysis from the China Biobank Project, a prospective nationwide multicenter population study. Lumbar spine (L₁ -L₂ ) trabecular volumetric bone mineral density (vBMD) was derived from these scans using quantitative computed tomography (QCT) software and the American College of Radiology QCT diagnostic criteria for osteoporosis were applied. Geographic regional differences in the prevalence of osteoporosis were assessed and the age-standardized, population prevalence of osteoporosis in Chinese men and women was estimated from the 2010 China census. The prevalence of osteoporosis by QCT for the Chinese population aged >50 years was 29.0% for women and 13.5% for men, equating to 49.0 million and 22.8 million, respectively. In women, this rate is comparable to estimates from dual-energy X-ray absorptiometry (DXA), but in men, the prevalence is double. Prevalence varied geographically across China, with higher rates in the southwest and lower rates in the northeast. Trabecular vBMD decreased with age in both men and women. Women had higher peak trabecular vBMD (185.4 mg/cm³ ) than men (176.6 mg/cm³ ) at age 30 to 34 years, but older women had lower trabecular vBMD (62.4 mg/cm³ ) than men (92.1 mg/cm³ ) at age 80 years. We show that LDCT-based opportunistic screening could identify large numbers of patients with low lumbar vBMD, and that future cohort studies are now required to evaluate the clinical utility of such screening in terms of fracture prevention and supporting national health economic analyses. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR)..

Soft-tissue spectral subtraction improves transcutaneous Raman estimates of murine bone strength in vivo

Transcutaneous determination of a bone's Raman spectrum is challenging because the type I collagen in the overlying soft tissue is spectroscopically identical to that in bone. In a previous transcutaneous study of murine tibiae, we developed a library-based model called SOLD to unmix spatially offset Raman measurements into three spectra: a bone estimate, a soft tissue estimate, and a residual. Here, we demonstrate the value of combining the bone estimate and the residual to produce a "top layer subtracted" (tls) spectrum. We report superior prediction of two standard bone metrics (volumetric bone mineralization density and maximum torque) using partial least squares regression models based upon tls spectra rather than SOLD bone estimates, implying that the spectral residuals contain useful information. Simulations reinforce experimental in vivo findings. This chemometric approach, which we denote as SOLD/TLS, could have broad applicability in situations where comprehensive spectral libraries are difficult to acquire.

Does Bone Mineral Apparent Density Facilitate Accurate Identification of Osteoporosis in the Short Postmenopausal Women?

OBJECTIVE

Height is one of the most important aspects affecting the areal bone mineral density (BMD). There are several height adjustments in children but none in widespread use for adults. This is specifically a problem in ethnic groups where mean height is substantially lower. We hypothesized that height adjustment of areal BMD would reduce the misclassification in short individuals.

MATERIALS AND METHODS

This is a retrospective study involving 373 postmenopausal women. Their records were reviewed and bone mineral apparent density (BMAD) were calculated. Areal BMD T-scores and BMAD T-scores were then compared.

RESULTS

The mean height of the cohort was 154.4 cm. There were 47 women who were defined as short (≤147 cm). In short women, BMAD neither showed improvement nor decrement in T-scores, and BMAD T-scores predicted more number of osteoporosis than BMD T-scores. When divided into height ranges, taller women (>160 cm) showed worsening of BMAD T-scores as compared to BMD T-scores (Chi-square test for trend P < 0.001). Hence, BMAD might actually "correct" for larger bone and not shorter bones.

CONCLUSION

BMAD was not found to be a suitable alternative in short postmenopausal women to accurately determine whether the low bone density in them is because of dual-energy X-ray absorptiometry artifact or whether they truly have a low density.

Regional bone mineral density differences measured by quantitative computed tomography: does the standard clinically used L1-L2 average correlate with the entire lumbosacral spine?

BACKGROUND CONTEXT

Quantitative computed tomography (QCT) of the lumbar spine is used as an alternative to dual-energy X-ray absorptiometry in assessing bone mineral density (BMD). The average BMD of L1-L2 is the standard reportable metric used for diagnostic purposes according to current recommendations. The density of L1 and L2 has also been proposed as a reference value for the remaining lumbosacral vertebrae and is commonly used as a surrogate marker for overall bone health. Since regional BMD differences within the spine have been proposed, it is unclear if the L1-L2 average correlates with the remainder of the lumbosacral spine.

PURPOSE

The aim of this study was to determine possible BMD variations throughout the lumbosacral spine in patients undergoing lumbar fusion and to assess the correlation between the clinically used L1-L2 average and the remaining lumbosacral vertebral levels.

STUDY DESIGN/SETTING

This is a retrospective case series.

PATIENT SAMPLE

Patients undergoing posterior lumbar spinal fusion from 2014 to 2017 at a single, academic institution with available preoperative CT imaging were included in this study.

OUTCOME MEASURES

The outcome measure was BMD measured by QCT.

METHODS

Standard QCT measurements at the L1 and L2 vertebra and additional experimental measurements of L3, L4, L5, and S1 were performed. Subjects with missing preoperative lumbar spine CT imaging were excluded. The correlations between the L1-L2 average and the other vertebral bodies of the lumbosacral spine (L3, L4, L5, S1) were evaluated.

RESULTS

In total, 296 consecutive patients (55.4% female, mean age of 63.1 years) with available preoperative CT were included. The vertebral BMD values showed a gradual decrease from L1 to L3 and increase from L4 to S1 (L1=118.8 mg/cm³, L2=116.6 mg/cm³, L3=112.5 mg/cm³, L4=122.4 mg/cm³, L5=135.3 mg/cm³, S1=157.4 mg/cm³). There was strong correlation between the L1-L2 average and the average of the other lumbosacral vertebrae (L3-S1) with a Pearson's correlation coefficient (r=0.85). We also analyzed the correlation between the L1-L2 average and each individual lumbosacral vertebra. Similar relationships were observed (r value, 0.67-0.87), with the strongest correlation between the L1-L2 average and L3 (r=0.87).

CONCLUSIONS

Our data demonstrate regional BMD differences throughout the lumbosacral spine. Nevertheless, there is high correlation between the clinically used L1-L2 average and the BMD values in the other lumbosacral vertebrae. We, therefore, conclude the standard clinically used L1-L2 BMD average is a useful bone quantity measure of the entire lumbosacral spine in patients undergoing lumbar spinal fusion.

DXA-based variables and osteoporotic fractures in Lebanese postmenopausal women

INTRODUCTION

The aim of this study was to assess DXA-based variables (bone mineral density, bone mineral apparent density, compressive strength index of the femoral neck and trabecular bone score) in Lebanese postmenopausal women having presented a previous fracture.

MATERIALS AND METHODS

One thousand Lebanese postmenopausal women between 45 and 89 years participated in this study. The women were recruited by advertisements offering bone mineral density measurements at a reduced cost. Subjects with previous history of radiotherapy or chemotherapy were excluded. Informed written consent was obtained from all the participants.

RESULTS

Femoral neck compressive strength index (FN CSI) was significantly (P<0.001) associated with the presence of fracture using a simple logistic regression (odds ratio=0.51 [0.385-0.653]). When a multivariate logistic regression analysis was performed with the presence of fracture as a dependent variable and each of age, FN BMD and FN CSI as independent variables, only FN BMD (P=0.005) and FN CSI (P=0.004) were found to be associated with the presence of fracture.

CONCLUSION

This study suggests that FN CSI is associated with history of osteoporotic fractures in postmenopausal women. The use of FN CSI in clinical practice may help to identify patients with high risk of fracture.

LEVEL OF EVIDENCE

Epidemiological study, level IV.

A comparative study of dual-X-ray absorptiometry and quantitative ultrasonography for the evaluating bone status in subjects with Rett syndrome

Rett syndrome, an X-linked neurodevelopmental disorder primarily affecting girls, is frequently characterized by a reduced bone mineral density (BMD) with an increased risk of fragility fractures. The aim of the study was to assess bone status by DXA technique and by quantitative ultrasound (QUS) in subjects with Rett syndrome and to evaluate which DXA or QUS parameters better correlate with clinical features. In 156 Rett subjects (mean age 13.6 ± 8.2 years) and in 62 controls, we measured BMD at femoral neck (BMD-FN) and at total femur (BMD-TF). Apparent volumetric bone mineral density (vBMAD) was also calculated. In all subjects, QUS parameters at phalanges by Bone Profiler-IGEA (amplitude-dependent speed of sound: AD-SoS and bone transmission time: BTT) were evaluated. We found that both DXA parameters and QUS parameters were significantly lower in Rett subjects than in controls. All clinical characteristics were positively correlated to BMD-FN, BMD-TF, AD-SoS, and BTT (p < 0.001) but not with vBMAD-FN. All ultrasonographic parameters were significantly correlated to BMD-FN and BMD-TF, whereas vBMAD-FN showed only positive significant correlation with densitometric parameters (p < 001). In Rett subjects BMD-FN was predicted primarily by weight and movement capacity, whereas vBMAD-FN was predicted by weight, height, and calcium intake. Moreover, AD-SoS was predicted by weight, height, and age, while BTT was predicted only by height. In conclusion, in our study the performance of QUS at phalanges was similar to those of BMD at femur, therefore, both areal BMD at femur and QUS at phalanges (AD-SoS and BTT) may be equally useful in the evaluation of skeletal status in Rett patients.

The ratio of anterior and posterior vertebral heights reinforces the utility of DXA in assessment of vertebrae strength

The objective of the study was to introduce a new parameter describing bone strength with greater precision than the widely used antero-posterior DXA (dual-energy X-ray absorptiometry), which measures areal bone mineral density (aBMD). The adjusted areal bone mineral density (AaBMD) defined as the ratio between aBMD and h a/h p (h a and h p: anterior and posterior vertebral body heights measured on the lateral view, respectively) is proposed: AaBMD = aBMD/(h a/h p). The utility of AaBMD in prediction of bone strength was assessed by in vitro measurements of cadaver L3 vertebrae. The AaBMD of 31 vertebrae was correlated with the ultimate stress (P max) and load (F max) values obtained in mechanical tests. The correlations were compared to those obtained for aBMD and for volumetric bone mineral density (vBMD) measured by computed tomography. The correlation of AaBMD to F max adjusted for donor's age was significantly higher than for aBMD and vBMD (r = 0.740, 0.658, and 0.609, respectively, p < 0.05). The differences between partial correlation coefficients for P max to AaBMD, aBMD and vBMD relationships were smaller (r = 0.764, 0.720, and 0.732, respectively, p < 0.05), but also showed the superiority of AaBMD. Combining antero-posterior DXA aBMD and the lateral h a/h p ratio, measured, for example, by the Vertebral Fracture Assessment software of the new generation of DXA devices, seems to accurately predict the mechanical vertebral parameters related to bone strength. It is assumed that the proposed AaBMD parameter may be more predictive for fracture risk assessment, which requires further studies.

Increased bone mineral density and decreased prevalence of osteoporosis in cervical ossification of the posterior longitudinal ligament: a case-control study

Bone and mineral metabolism has been reported to affect the development of the ossification of the posterior longitudinal ligament (OPLL). The aim of this study was to compare bone mineral densities (BMD) and rate of osteoporosis between cervical OPLL and a matched control group. We also investigated the correlation of BMD with the number of cervical spine levels involved with OPLL. From 1999 to August 2011, 178 patients with cervical OPLL underwent dual-energy X-ray absorptiometry (DXA) at our institute. The control group was age-, sex-, and body mass index (BMI)-matched with the OPLL group on a 1:1 basis. BMD was measured at the lumbar spine (L1-L4), femoral neck, and total femur using DXA. Age, sex, and BMI were the same in the OPLL and control groups. BMDs of the OPLL and control groups were significantly different in the lumbar spine, femoral neck, and total femur (p = 0.0001, 0.0001, 0.009, respectively). Rates of osteopenia and osteoporosis were lower in the OPLL than in the control group according to lumbar spine and femoral neck DXA (p = 0.01, 0.03, respectively). A positive correlation was observed between lumbar spine BMD and the number of cervical spine levels involved with OPLL (p = 0.004).

Combining areal DXA bone mineral density and vertebrae postero-anterior width improves the prediction of vertebral strength

OBJECTIVE

Areal bone mineral density (aBMD) measured by dual-energy X-ray absorptiometry (DXA) is an important determinant of bone strength (BS), despite the fact that the correlation between aBMD and BS is relatively weak. Parameters that describe BS more accurately are desired. The aim of this study was to determine whether the geometrical corrections applied to aBMD would improve its ability for BS prediction. We considered new parameters, estimated from a single DXA measurement, as well as BMAD (bone mineral apparent density) reported in the literature.

MATERIALS AND METHODS

In vitro studies were performed with the L3 vertebrae from 20 cadavers, which were studied with DXA and quantitative computed tomography (QCT). A mechanical strength assessment was carried out. Two new parameters were introduced: vBMD(min) = aBMD/W(PA)(min) and vBMD(av) = aBMD/W(PA)(av) (W PA(min) -minimal vertebral body width in postero-anterior (PA) view, W(PA)(av) - average PA vertebral body width). Volumetric BMD measured by QCT (vBMD), aBMD, BMAD, vBMD(min), and vBMD(av) were correlated to ultimate load and ultimate stress (P(max)) to find the best predictor of vertebrae BS.

RESULTS

The coefficients of correlation between P(max) and vBMD(min), vBMD(av), as well as BMAD, were r = 0.626 (p = 0.005), r = 0.610 (p = 0.006) and r = 0.567 (p = 0.012), respectively. Coefficients for vBMD and aBMD are r = 0.648 (p = 0.003) and r = 0.511 (p = 0.03), respectively.

CONCLUSIONS

Our results showed that aBMD normalized by vertebrae dimensions describes vertebrae BS better than aBMD alone. The considered indices vBMD(av), vBMD(min), and BMAD can be measured in routine PA DXA and considerably improve BS variability prediction. vBMD(min) is superior compared to vBMD(av) and BMAD.

Failure strength of human vertebrae: prediction using bone mineral density measured by DXA and bone volume by micro-CT

Significant relationships exist between areal bone mineral density (BMD) derived from dual energy X-ray absorptiometry (DXA) and bone strength. However, the predictive validity of BMD for osteoporotic vertebral fractures remains suboptimal. The diagnostic sensitivity of DXA in the lumbar spine may be improved by assessing BMD from lateral-projection scans, as these might better approximate the objective of measuring the trabecular-rich bone in the vertebral body, compared to the commonly-used posterior-anterior (PA) projections. Nowadays, X-ray micro-computed tomography (μCT) allows non-destructive three-dimensional structural characterization of entire bone segments at high resolution. In this study, human lumbar cadaver spines were examined ex situ by DXA in lateral and PA projections, as well as by μCT, with the aims (1) to investigate the ability of bone quantity measurements obtained by DXA in the lateral projection and in the PA projection, to predict variations in bone quantity measurements obtained by μCT, and (2) to assess their respective capabilities to predict whole vertebral body strength, determined experimentally. Human cadaver spines were scanned by DXA in PA projections and lateral projections. Bone mineral content (BMC) and BMD for L2 and L3 vertebrae were determined. The L2 and L3 vertebrae were then dissected and entirely scanned by μCT. Total bone volume (BV(tot)=cortical+trabecular), trabecular bone volume (BV), and trabecular bone volume fraction (BV/TV) were calculated over the entire vertebrae. The vertebral bodies were then mechanically tested to failure in compression, to determine ultimate load. The variables BV(tot), BV, and BV/TV measured by μCT were better predicted by BMC and BMD measured by lateral-projection DXA, with higher R(2) values and smaller standard errors of the estimate (R(2)=0.65-0.90, SEE=11%-18%), compared to PA-projection DXA (R(2)=0.33-0.53, SEE=22%-34%). The best predictors of ultimate load were BV(tot) and BV assessed by μCT (R(2)=0.88 and R(2)=0.81, respectively), and BMC and BMD from lateral-projection DXA (R(2)=0.82 and R(2)=0.70, respectively). Conversely, BMC and BMD from PA-projection DXA were lower predictors of ultimate load (R(2)=0.49 and R(2)=0.37, respectively). This ex vivo study highlights greater capabilities of lateral-projection DXA to predict variations in vertebral body bone quantity as measured by μCT, and to predict vertebral strength as assessed experimentally, compared to PA-projection DXA. This provides basis for further exploring the clinical application of lateral-projection DXA analysis.

Chronic low back pain is associated with reduced vertebral bone mineral measures in community-dwelling adults

Background

Chronic low back pain (CLBP) experienced in middle-age may have important implications for vertebral bone health, although this issue has not been investigated as a primary aim previously. This study investigated the associations between CLBP and dual energy X-ray absorptiometry (DXA)-derived vertebral bone mineral measures acquired from postero-anterior and lateral-projections, among community-dwelling, middle-aged adults.

Methods

Twenty-nine adults with CLBP (11 male, 18 female) and 42 adults with no history of LBP in the preceding year (17 male, 25 female) were evaluated. Self-reported demographic and clinical data were collected via questionnaires. Areal bone mineral density (aBMD) was measured in the lumbar spine by DXA. Apparent volumetric (ap.v) BMD in the lumbar spine was also calculated. Multiple linear regression models were used to examine associations between study group (CLBP and control) and vertebral DXA variables by gender, adjusting for height, mass and age.

Results

There was no difference between groups by gender in anthropometrics or clinical characteristics. In the CLBP group, the mean (SD) duration of CLBP was 13.3 (10.4) years in males and 11.6 (9.9) years in females, with Oswestry Disability Index scores of 16.2 (8.7)% and 15.4 (9.1)%, respectively. Males with CLBP had significantly lower adjusted lateral-projection aBMD and lateral-projection ap.vBMD than controls at L3 with mean differences (standard error) of 0.09 (0.04) g/cm² (p = 0.03) and 0.02 (0.01) g/cm³ (p = 0.04). These multivariate models accounted for 55% and 53% of the variance in lateral-projection L3 aBMD and lateral-projection L3 ap.vBMD.

Conclusions

CLBP in males is associated with some lumbar vertebral BMD measures, raising important questions about the mechanism and potential clinical impact of this association.

Measurement of subregional vertebral bone mineral density in vitro using lateral projection dual-energy X-ray absorptiometry: validation with peripheral quantitative computed tomography

Although a strong relationship exists between areal bone mineral density (aBMD) derived from dual-energy X-ray absorptiometry (DXA) and bone strength, the predictive validity of aBMD for osteoporotic vertebral fractures remains suboptimal. The diagnostic sensitivity of DXA may be improved by assessing aBMD within vertebral subregions, rather than relying on an estimate derived from the total area of the vertebra. The objective of this study was to validate a method of measuring subregional vertebral aBMD in vitro using lateral-projection DXA against subregional volumetric BMD (vBMD) measured with peripheral quantitative computed tomography (pQCT). A mixed set of 49 lumbar and thoracic vertebrae from 25 donors were scanned using lateral-projection DXA and pQCT. aBMD and apparent vBMD were measured in 7 vertebral regions (1 total area and 6 subregions) from the lateral DXA scan. vBMD was calculated in anatomically equivalent regions from pQCT scan data, using a customised software program designed to increase efficiency of the analysis process. Significant differences in densitometric parameters between subregions were observed by DXA and pQCT (P < 0.01). Subregional vBMD derived from pQCT was explained by a significant proportion of the variance in DXA-derived aBMD (R (2) = 0.51-0.67, P < 0.05) and apparent vBMD (R (2) = 0.64-0.75, P < 0.05). These results confirm the validity of measuring aBMD in vertebral subregions using lateral-projection DXA. The clinical significance should now be explored.

Effect of thiazides on bone mineral density in children with idiopathic hypercalciuria

To determine the effect of thiazide treatment on bone mineral density (BMD) in children with idiopathic hypercalciuria (IH) and osteopenia, we reviewed the case notes of 22 children aged 11.7 ± 2.7 years diagnosed with IH and osteopenia who had received thiazides for 2.4 years. The data on this group were compared with those of 32 IH children with osteopenia aged 11.2 ± 2.7 years who had not received thiazide treatment. By the end of the follow-up period, the z-BMD had improved spontaneously in 23 of the 32 control children (72%) and in 12 of the 22 patients on thiazides (54%). Although treated patients had a higher body mass index (BMI) and a higher BMD following treatment, the differences became statistically negligible when these parameters were expressed as z-BMD or as bone mineral apparent density (BMAD). In contrast, within the control group, there were significant differences in BMAD and z-BMD at the end of the follow-up. Patients who had an improved z-BMD at the end of the treatment also showed an increase in their BMI. Based on these results, we conclude that thiazide treatment does not improve the z-BMD in children with IH. More than half of the children suffering from IH enrolled in our study showed a spontaneous improvement in their z-BMD, which was more evident when the initial BMAD was not low and when their BMI increased during the follow-up period.

Trabecular bone mineral density measurement using thoracic and lumbar quantitative computed tomography

PURPOSE

To evaluate the agreement of bone mineral density (BMD) between lumbar (L) and individual thoracic (T) vertebrae and identify a standard thoracic spine level for BMD assessment in cardiac computed tomography (CT) images.

MATERIALS AND METHODS

Three hundred subjects who underwent simultaneous chest and abdomen CT scans for clinical indications were included. A calibration phantom that extended from the first thoracic spine (T(1)) to the fifth lumbar (L(5)) was employed. Vertebral BMD were measured by QCT 5000 and NVivo systems. The association between three consecutive lumbar (L1-L3) and thoracic BMD (3T, initiation site equivalent to left main coronary caudally) was evaluated.

RESULTS

There was a gradual decrease in BMD values from T(1) to L(3,) subsequently increasing in L(4) and L(5) in both genders. When stratified by gender, 3T BMD was significantly higher versus L(1-3) BMD (156.9 versus 141.9vmg/cm(3), P < .001) for women as well as for men (164.8 versus 151.0 mg/cm(3), P < .001). There is good correlation between 3T and L(1-3) BMD, the Pearson's correlation coefficients are 0.91 and 0.93 for women and men, respectively. We further analyzed the associations between L(1-3) and any individual spine of T(1)-L(5) and similar relationships were observed (r value, 0.62-0.98). The intraobserver, interobserver, and interscan variation measurement of thoracic quantitative CT was 2.5 (1.0, 95% CI 0.099-1.004); 2.6 (1.0, 95CI% 0.992-1.007), and 2.8% (1.0,95% 0.0994-1.008), respectively.

CONCLUSION

The 3T BMD was highly correlated with L(1-3) BMD. Thoracic BMD can be measured during cardiac and lung CT imaging without need for additional participant burden or radiation dose. This highly reproducible methodology is actively being applied to large cohort studies to evaluate the prevalence of osteoporosis and track BMD over time.

Mechanical loading during growth is associated with plane-specific differences in vertebral geometry: A cross-sectional analysis comparing artistic gymnasts vs. non-gymnasts

Lumbar spine geometry, density and indices of bone strength were assessed relative to menarche status, using artistic gymnastics exposure during growth as a model of mechanical loading. Paired posteroanterior (pa) and supine lateral (lat) DXA scans of L3 for 114 females (60 ex/gymnasts and 54 non-gymnasts) yielded output for comparison of paired (palat) versus standard pa and lat outcomes. BMC, areal BMD, vertebral body dimensions, bone mineral apparent density (BMAD), axial compressive strength (IBS) and a fracture risk index were evaluated, modeling vertebral body geometry as an ellipsoid cylinder. Two-factor ANCOVA tested statistical effects of gymnastic exposure, menarche status and their interaction, adjusting for age and height as appropriate. Compared to non-gymnasts, ex/gymnasts exhibited greater paBMD, paBMC, paWidth, pa Cross-sectional area (CSA), paVolume, latBMD, latBMAD, palatCSA and palatIBS (p<0.05). Non-gymnasts exhibited greater latDepth/paWidth, latBMC/paBMC, latVHeight, latArea and Fracture Risk Index. Using ellipsoid vertebral geometric models, no significant differences were detected for pa or palat BMAD. In contrast, cuboid model results (Carter et al., 1992) suggested erroneous ex/gymnast paBMAD advantages, resulting from invalid assumptions of proportional variation in linear skeletal dimensions. Gymnastic exposure was associated with shorter, wider vertebral bodies, yielding greater axial compressive strength and lower fracture risk, despite no BMAD advantage. Our results suggest the importance of plane-specific vertebral geometric adaptation to mechanical loading during growth. Paired scan output provides a more accurate assessment of this adaptation than pa or lat plane scans alone.

Bone metabolic abnormalities associated with well-controlled type 1 diabetes (IDDM) in young adult women: a disease complication often ignored or neglected

OBJECTIVES

This investigation on a homogenous cohort of young adult Caucasian type 1 diabetic (IDDM) patients (1) aimed at studying the occurrence of low bone mineral density (BMD) at an early stage prior to menopause (i.e., during the first decade after peak bone mass) and (2) elucidating the possible mechanisms underlying IDDM-induced bone complication.

METHODS

Twenty-seven female patients with insulin-treated and well-controlled diabetes, without renal complications, and 32 well-matched healthy controls, aged between 30 and 40 years and fulfilling rigorous inclusion criteria to minimize bone-confounding factors, were enrolled. Areal BMD was evaluated by dual energy X-ray absorptiometry at axial (lumbar spine) and appendicular (femur) sites, using diagnostic WHO reference (T-scores). Osteoblast functions, bone metabolism, related key minerals, and 2 osteoclast-stimulating calciotropic hormones regulating their serum levels were assessed biochemically.

RESULTS

The number of cases with low BMD (T-score below -1.1 SD) was almost 2-fold greater (p < 0.01) in the IDDM group. BMD was significantly lower in this group for 3 lumbar sites (p < 0.01) and femur Ward's triangle (p < 0.05). Bone formation was reduced, as evidenced by the suppressions of osteocalcin (OC; p < 0.01) and IGF-I (p < 0.001). However, bone alkaline phosphatase (bALP) was induced (p < 0.01), in contrast to what is usually observed in cases of reduced bone formation. Correlated total ALP activity was also significantly increased. There was no change in the specific marker of bone resorption (urinary deoxypyridinoline). Serum calcium was significantly elevated, particularly after adjustment for albumin (p < 0.001), despite lower 1,25(OH)(2)D(3) (p < 0.001) and no elevation of PTH. All significant bone-related biochemical changes were significantly correlated with glycosylated hemoglobin, a clinical indicator of long-term glycemic control, indicating a direct effect of the disease.

CONCLUSIONS

Bone loss in the IDDM group results from a decrease in bone formation rather than an increase of bone resorption. The induction of bALP is indicative of impaired osteoblast differentiation and maturation, which delayed (down-regulated) later stages of matrix mineralization, as evidenced by lower OC and BMD.

Regional distribution of spine and hip QCT BMD responses after one year of once-monthly ibandronate in postmenopausal osteoporosis

In the published placebo-controlled Ibandronate Quality (IQ) study, 12 months of once-monthly oral ibandronate increased femoral and vertebral integral and trabecular bone mineral density (BMD) measured by quantitative computed tomography (QCT). Ibandronate showed significant improvements versus placebo in finite element analysis of femoral and vertebral strength. This post hoc analysis examined QCT BMD changes in novel superior and inferior vertebral volumes of interest (VOIs) and femoral and vertebral subcortical, extended cortical, and extended trabecular VOIs. Ninety-three postmenopausal women (BMD(a)T-scores< or =-2.0 at lumbar spine, total hip, or femoral neck) received ibandronate 150 mg/month (n=47) or placebo (n=46) for 12 months. QCT with Medical Imaging Analysis Framework (MIAF)-Spine and MIAF-Femur used automated segmentation and coordinate system-based identification of integral, cortical, subcortical, and trabecular VOIs and combinations (extended cortical=cortical+subcortical; extended trabecular=trabecular+subcortical). Between-group differences in mean percentage changes from baseline were determined by treatment- and center-adjusted analysis of variance. P values were post hoc, exploratory, descriptive, and unadjusted for multiple comparisons. Ibandronate increased vertebral superior and inferior trabecular and extended cortical midsection BMD (4.9%, p=0.032; 4.6%, p=0.055; 3.9%, p=0.014, respectively) versus placebo. Femoral BMD treatment differences (ibandronate versus placebo) were significant in total hip (extended trabecular 4.0%, p=0.005; extended cortical 1.5%, p=0.047; subcortical 3.7%, p=0.009), trochanter (extended trabecular 5.2%, p=0.007; extended cortical 2.4%, p=0.01), and extended trabecular femoral neck (4.0%, p=0.02). Monthly oral ibandronate for 12 months improved QCT BMD versus placebo in the vertebral periphery, subcortical total hip, and all femoral extended trabecular regions.

Novel assessment of subregional bone mineral density using DXA and pQCT and subregional microarchitecture using micro-CT in whole human vertebrae: applications, methods, and correspondence between technologies

In the clinical environment dual-energy X-ray absorptiometry (DXA) is the current tool of first choice for assessing and monitoring skeletal integrity. A major drawback of standard DXA is that the bone mineral density (BMD) data cannot be used with certainty to predict who will sustain a vertebral fracture. However, measurement of BMD within vertebral subregions, instead of relying on a gross estimate of vertebral BMD, may improve diagnostic sensitivity. The aim of this article was to describe a validation study for subregional BMD measurement using lateral-projection DXA and to present preliminary data. Concurrent validity of measuring subregional BMD with DXA was established against measures of volumetric subregional BMD from peripheral quantitative computed tomography (pQCT) and subregional bone volume fraction from microCT at the L2 vertebral body in 8 cadaver spine specimens. The novel approaches for measuring subregional parameters with each imaging modality are described. Significant differences in bone parameters between vertebral subregions were observed for each imaging modality (p<0.05). Correspondence ranged from R(2)=0.01-0.79 and R(2)=0.06-0.80 between "DXA vs. pQCT" and "DXA vs. micro-CT," respectively. For both imaging modalities, correspondence with DXA was high for centrally and anteriorly positioned subregions. These data provide a basis for larger studies to examine the biological significance of heterogeneity in vertebral BMD.

Measuring and interpreting age-related loss of vertebral bone mineral density in a medieval population

This study investigates the age- and sex-related patterns in vertebral bone mineral density (BMD) and the relationship between BMD and vertebral osteophytosis (VO), using a specialized peripheral densitometer in a skeletal sample excavated from the British medieval village Wharram Percy. A total of 58 individuals were divided by sex into three broad age categories (18-29, 30-49, 50+ years.). Each fourth intact vertebral centra was scored for VO and 5-mm thick coronal sections scanned in a specialized peripheral densitometer (GE Lunar Piximus DXA). Changes in BMD associated with age, sex, and VO severity were examined in the whole vertebral section, a strictly trabecular region, and a primarily cortical region of bone separately. Significant change in vertebral BMD was found to occur by middle age with little or no statistical change in BMD between middle and old age. Females appear to suffer greater bone loss at an earlier age with no change in BMD between middle and old age, whereas males show a more steady loss of BMD across the age groups. The bone mineral content and BMD of the cortical region is higher in individuals with pronounced/severe osteophytosis. The unusual age- and sex-related patterns of change in vertebral BMD at Wharram Percy are compared with the patterns of age-related change from recent longitudinal population-based studies. The results emphasize the different pattern of bone loss in young adulthood seen in trabecular regions of the skeleton and highlight the importance of consideration of degenerative joint disease in BMD studies. The influence of lifestyle factors on vertebral BMD in this medieval population is also discussed.

Quantitative computed tomography

Quantitative computed tomography (QCT) was introduced in the mid 1970s. The technique is most commonly applied to 2D slices in the lumbar spine to measure trabecular bone mineral density (BMD; mg/cm(3)). Although not as widely utilized as dual-energy X-ray absortiometry (DXA) QCT has some advantages when studying the skeleton (separate measures of cortical and trabecular BMD; measurement of volumetric, as opposed to 'areal' DXA-BMDa, so not size dependent; geometric and structural parameters obtained which contribute to bone strength). A limitation is that the World Health Organisation (WHO) definition of osteoporosis in terms of bone densitometry (T score -2.5 or below using DXA) is not applicable. QCT can be performed on conventional body CT scanners, or at peripheral sites (radius, tibia) using smaller, less expensive dedicated peripheral CT scanners (pQCT). Although the ionising radiation dose of spinal QCT is higher than for DXA, the dose compares favorably with those of other radiographic procedures (spinal radiographs) performed in patients suspected of having osteoporosis. The radiation dose from peripheral QCT scanners is negligible. Technical developments in CT (spiral multi-detector CT; improved spatial resolution) allow rapid acquisition of 3D volume images which enable QCT to be applied to the clinically important site of the proximal femur, more sophisticated analysis of cortical and trabecular bone, the imaging of trabecular structure and the application of finite element analysis (FEA). Such research studies contribute importantly to the understanding of bone growth and development, the effect of disease and treatment on the skeleton and the biomechanics of bone strength and fracture.

Generation of a 3D proximal femur shape from a single projection 2D radiographic image

Generalized Procrustes analysis and thin plate splines were employed to create an average 3D shape template of the proximal femur that was warped to the size and shape of a single 2D radiographic image of a subject. Mean absolute depth errors are comparable with previous approaches utilising multiple 2D input projections.

INTRODUCTION

Several approaches have been adopted to derive volumetric density (g cm(-3)) from a conventional 2D representation of areal bone mineral density (BMD, g cm(-2)). Such approaches have generally aimed at deriving an average depth across the areal projection rather than creating a formal 3D shape of the bone.

METHODS

Generalized Procrustes analysis and thin plate splines were employed to create an average 3D shape template of the proximal femur that was subsequently warped to suit the size and shape of a single 2D radiographic image of a subject. CT scans of excised human femora, 18 and 24 scanned at pixel resolutions of 1.08 mm and 0.674 mm, respectively, were equally split into training (created 3D shape template) and test cohorts.

RESULTS

The mean absolute depth errors of 3.4 mm and 1.73 mm, respectively, for the two CT pixel sizes are comparable with previous approaches based upon multiple 2D input projections.

CONCLUSIONS

This technique has the potential to derive volumetric density from BMD and to facilitate 3D finite element analysis for prediction of the mechanical integrity of the proximal femur. It may further be applied to other anatomical bone sites such as the distal radius and lumbar spine.

Divergent effects of glucocorticoids on cortical and trabecular compartment BMD in childhood nephrotic syndrome

Glucocorticoid (GC) effects on skeletal development have not been established. The objective of this pQCT study was to assess volumetric BMD (vBMD) and cortical dimensions in childhood steroid-sensitive nephrotic syndrome (SSNS), a disorder with minimal independent deleterious skeletal effects. Tibia pQCT was used to assess trabecular and cortical vBMD, cortical dimensions, and muscle area in 55 SSNS (age, 5-19 yr) and >650 control participants. Race-, sex-, and age-, or tibia length-specific Z-scores were generated for pQCT outcomes. Bone biomarkers included bone-specific alkaline phosphatase and urinary deoxypyridinoline. SSNS participants had lower height Z-scores (p < 0.0001) compared with controls. In SSNS, Z-scores for cortical area were greater (+0.37; 95% CI = 0.09, 0.66; p = 0.01), for cortical vBMD were greater (+1.17; 95% CI = 0.89, 1.45; p < 0.0001), and for trabecular vBMD were lower (-0.60; 95% CI, = -0.89, -0.31; p < 0.0001) compared with controls. Muscle area (+0.34; 95% CI = 0.08, 0.61; p = 0.01) and fat area (+0.56; 95% CI = 0.27, 0.84; p < 0.001) Z-scores were greater in SSNS, and adjustment for muscle area eliminated the greater cortical area in SSNS. Bone formation and resorption biomarkers were significantly and inversely associated with cortical vBMD in SSNS and controls and were significantly lower in the 34 SSNS participants taking GCs at the time of the study compared with controls. In conclusion, GCs in SSNS were associated with significantly greater cortical vBMD and cortical area and lower trabecular vBMD, with evidence of low bone turnover. Lower bone biomarkers were associated with greater cortical vBMD. Studies are needed to determine the fracture implications of these varied effects.

Effect of total hip bone area on osteoporosis diagnosis and fractures

DXA is affected by skeletal size, with smaller bones giving lower areal BMD despite equal material density. Whether this size effect confounds the use of BMD as a diagnostic and fracture risk assessment tool is unclear. We identified 16,205 women of white ethnicity >or=50 yr of age undergoing baseline hip assessment with DXA (1998-2002) from a population-based database that contains all clinical DXA test results for the Province of Manitoba, Canada. Total hip measurements were categorized according to quartile in total hip bone area (Q1 = smallest, Q4 = largest). Longitudinal health service records were assessed for the presence of nontraumatic osteoporotic fracture codes during a mean of 3.2 yr of follow-up after BMD testing (757 osteoporotic fractures, 186 hip fractures). Total hip bone area strongly affected osteoporosis diagnosis with much higher rates in Q1 (14.4%) than Q4 (8.9%). However, incident fracture rates were constant across all area quartiles, and prevalent fractures were paradoxically fewer in smaller area quartiles (p < 0.001 for trend). Age was a potential confounder that correlated positively with area (r = 0.12, p < 0.0001). When age was not included in a Cox regression model, Q1 seemed to have a lower rate of incident osteoporotic fractures (HR = 0.80, 95% CI = 0.66-0.98, reference Q4) and hip fractures (HR = 0.63, 95% CI = 0.43-0.94) for a given level of BMD. In age-adjusted regression models, total hip BMD was strongly predictive of incident osteoporotic fractures (HR per SD = 1.83, 95% CI = 1.68-1.99) and hip fractures (HR per SD = 2.80, 95% CI = 2.33-3.35), but there was no independent effect of bone area (categorical or continuous). Nested matched subgroup analysis and ROC analysis confirmed that bone area had no appreciable effect on incident fractures. We conclude that total hip areal BMD categorizes a substantially higher fraction of women with smaller bone area as being osteoporotic despite younger age. Incident fracture rates correlate equally well with BMD across all bone area quartiles when adjusted for age.

Fracture risk and bone mineral density in Turner syndrome

Bone health is a major lifelong concern in caring for women and girls with Turner syndrome (TS). There is an approximately 25% increase in fracture risk most of which is related to medium or high impact trauma. The long bones, especially of the forearm are predominantly affected. This fact may be due to a selective cortical bone deficiency in TS which is unrelated to hypogonadism. In addition, lack of adequate estrogen replacement can lead to trabecular bone deficiency and increase in vertebral compression fractures after age 45. Evaluation of bone density by dual X-ray absorptiometry (DEXA) is important, however, it should be used judiciously in TS in view of its inherent tendency to underestimate the bone density of people with short stature. Bone size-independent methods, such as QCT or volumetric transformation of DEXA data should be used in individuals shorter than 150 cm. Achieving optimal bone density is of critical importance for fracture prevention in TS, and should be pursued by timely introduction of hormone replacement therapy, adequate dose of estrogens during the young adult life, optimal calcium and vitamin D intake and regular physical exercise. In addition, other measures to prevent fall and trauma should be considered, including optimizing hearing and vision, avoiding contact sports and exercise to improve coordination.

Tarsal and metatarsal bone mineral density measurement using volumetric quantitative computed tomography

A new method for measuring bone mineral density (BMD) of the tarsal and metatarsals is described using volumetric quantitative computed tomography (VQCT) in subjects with diabetes mellitus and peripheral neuropathy. VQCT images of a single foot were acquired twice from eight subjects (mean age 51 [11 SD], seven males, one female). The cortical shells of the seven tarsal and five metatarsal bones were identified and semiautomatically segmented from adjacent bones. Volume and BMD of each bone were measured separately from the two acquired scans for each subject. Whole-bone semiautomatic segmentation measurement errors were determined as the root mean square coefficient of variation for the volume and BMD of 0.8% and 0.9%, respectively. In addition to the whole-bone segmentation methods, we performed atlas-based partitioning of subregions within the second metatarsal for all subjects, from which the volumes and BMDs were obtained for each subregion. The subregion measurement BMD errors (root mean square coefficient of variation) within the shaft, proximal end, and distal end were shown to vary by approximately 1% between the two scans of each subject. The new methods demonstrated large variations in BMDs between the 12 bones of the foot within a subject and between subjects, and between subregions within the second metatarsal. These methods can provide an important outcome measure for clinical research trials investigating the effects of interventions, aging, or disease progression on bone loss, or gain, in individual foot bones.

Assessment of spine bone mineral density in juvenile idiopathic arthritis: impact of scan projection

Although children with juvenile idiopathic arthritis (JIA) are at risk for vertebral fractures, recent conventional posterior-anterior (PA) spine dual-energy X-ray absorptiometry studies reported minimal areal bone mineral density (aBMD, g/cm2) deficits. Width-adjusted BMD (WA-BMD, g/cm3) represents the bone mineral content (BMC) from the lateral projection, excluding the dense cortical spinous processes, divided by the estimated vertebral body volume based on paired PA-lateral bone dimensions. Therefore, WA-BMD may be more sensitive to JIA effects on the predominantly trabecular vertebral body. Age- and sex-specific Z-scores for spine aBMD and WA-BMD were generated in 84 JIA subjects compared with healthy controls, aged 5-21 yr. JIA was associated with lower mean WA-BMD Z-scores (-0.78, 95% CI: -1.03, -0.53; p<0.001) and aBMD Z-scores (-0.26, 95% CI: -0.49, -0.02; p<0.05), compared with controls. WA-BMD Z-scores were significantly lower than aBMD Z-scores in JIA (p<0.001). A significant JIA by age interaction (p<0.001) indicated that the magnitude of the difference between WA-BMD and aBMD Z-scores was greater in younger subjects. In conclusion, WA-BMD may be more sensitive to disease effects in children because it selectively measures the trabecular-rich vertebral body and is independent of growth-related changes in BMC of the dense spinous processes.

Bone mass in young adults with Down syndrome

BACKGROUND

Down syndrome (DS) is a frequent cause of intellectual disability. With the increasing life expectancy of these patients, concerns have been raised about the risk of osteoporosis. In fact, several investigators have reported a reduced bone mass in DS. However, the results may be confounded by comorbid diseases, and differences in lifestyle habits and body size. Therefore, we planned to determine anthropometric and lifestyle factors influencing bone mineral density (BMD) in young adults with DS.

METHODS

Thirty-nine patients with DS (mean age 26 years) and 78 controls were studied. Areal BMD was measured by dual x-ray densitometry (DXA); volumetric BMD at the lumbar spine and femoral neck was estimated with published formulae.

RESULTS

DS patients had lower areal BMD than controls at all regions (spine, hip and total body). Height and projected bone area were also lower. There were no differences between both groups regarding estimated volumetric BMD at the femoral neck. However, spine volumetric BMD was also lower in DS than controls. In multivariate analysis, DS, male sex, little physical activity and low sunlight exposure were associated with lower spine volumetric BMD; on the other hand, fat mass and sunlight exposure were associated with femoral neck volumetric BMD.

CONCLUSION

This study shows that patients with DS had a reduced areal BMD, but it is in part a consequence of the reduced body size, particularly at the femoral neck. Physical activity and sunlight exposure are associated to volumetric BMD and should be stimulated in order to maintain an adequate bone mass in these patients.

In vivo 3D reconstruction of human vertebrae with the three-dimensional X-ray absorptiometry (3D-XA) method

We used a standard DXA device equipped with a C-arm to do in vivo reconstruction of human vertebrae from two orthogonal scans. This new technique, called 3D-XA (three-dimensional X-ray absorptiometry), allows the direct measurement of geometric parameters of the vertebrae with a good accuracy and precision.

INTRODUCTION

Geometric parameters are predictors of bone strength. A technique called three-dimensional X-ray absorptiometry (3D-XA) allows 3D reconstruction of bones from DXA scans. We used the 3D-XA method to reconstruct human vertebrae and to evaluate the method's in vitro accuracy and in vivo precision.

METHODS

A standard DXA device equipped with a C-arm was used. Calibration of its environment and identification of different anatomical landmarks of the vertebrae allows personalized 3D geometric reconstruction of vertebrae. Accuracy was calculated by reconstructing 16 dry human vertebrae by 3D-XA and CT scanner. In vivo inter-observer precision was calculated using 20 human spines.

RESULTS

The mean difference between 3D reconstruction by CT and 3D-XA was -0.2 +/- 1.3 mm. The in vivo mean difference of the 3D-XA method between the two rheumatologists was -0.1 +/- 0.8 mm. For geometric parameters, mean difference ranged from 0.4 to 0.9 mm. For cross-sectional area and vertebral body volume, it was 2.9% and 3.2%, respectively.

CONCLUSION

This study shows the good accuracy and precision of 3D-XA using a standard DXA device. It yields complementary information on bone geometry. Further studies are needed to evaluate if, coupled with bone density, it improves vertebral fracture risk prediction.

Osteoporosis in a female population from Bratislava--age-related BMD changes

PATIENTS AND METHODS

We analysed 498 women (n=498) in a Bratislava (BA) population aged 21 to 90. We measured bone mineral density (BMD) in the proximal femur with one densitometric instrument (DXA Osteocore II, France; dual energy X-ray absorptiometry), applying BMD and T-score values in three standard regions of interest: Neck (ROI1), Ward's area (ROI2), Trochanter (ROI3).

RESULTS

Measured values of T-score in ROI1, ROI2 had normal distribution and a lognormal distribution of frequency in ROI3. Using chi2-test (chi-square goodness-of-fit statistics), we determined the distribution of the frequency of T-score values and the percentage of osteoporosis incidence in the Bratislava female population. The osteoporosis incidence, according to T-score values measured in ROI1 was 2.40%, in ROI2 16.34% and in ROI3 3.83%. Following the division of women into ten-year intervals, the statistically significant sample averages of T-score values were decreasing in relation to age only for ROI2. Osteoporosis incidence in age intervals was rising with age for ROI2, for ROI1 the number of osteoporotic patients in the 61 to 70-year interval was lower than in the 41 to 50-year interval, and for ROI3 the number of osteoporotic patients in the 51 to 60-year interval was lower than in the 41 to 50-year interval. Except in the above-mentioned intervals, T-score values decreased in relation to age also in ROI1 and ROI3. According to the analysis of variance, the age category explains 9.6% of the overall variability of T-score values for ROI1, 24.7% for ROI2 and 11.70% for ROI3.

CONCLUSIONS

As in ROI2 (Ward's area) a greater fraction of trabecular bone is measured in comparison with ROI1 and ROI3, ROI2 reflects best the age-related BMD changes. In ROI1 and ROI3 the relation was distorted by a greater fraction of cortical bone in comparison with ROI2 and by osteoarthritis.

Prediction of clinical non-spine fractures in older black and white men and women with volumetric BMD of the spine and areal BMD of the hip: the Health, Aging, and Body Composition Study*

In a prospective study of 1446 black and white adults 70-79 yr of age (average follow-up, 6.4 yr), vertebral TrvBMD from QCT predicted non-spine fracture in black and white women and black men, but it was not a stronger predictor than total hip aBMD from DXA. Hip aBMD predicted non-spine fracture in black men.

INTRODUCTION

Areal BMD (aBMD) at multiple skeletal sites predicts clinical non-spine fractures in white and black women and white men. The predictive ability of vertebral trabecular volumetric BMD (TrvBMD) for all types of clinical non-spine fractures has never been tested or compared with hip aBMD. Also, the predictive accuracy of hip aBMD has never been tested prospectively for black men.

MATERIALS AND METHODS

We measured vertebral TrvBMD with QCT and hip aBMD with DXA in 1446 elderly black and white adults (70-79 yr) in the Health, Aging, and Body Composition Study. One hundred fifty-two clinical non-spine fractures were confirmed during an average of 6.4 yr of >95% complete follow-up. We used Cox proportional hazards regression to determine the hazard ratio (HR) and 95% CIs of non-spine fracture per SD reduction in hip aBMD and vertebral TrvBMD.

RESULTS

Vertebral TrvBMD and hip aBMD were both associated with risk of non-spine fracture in black and white women and black men. The age-adjusted HR of fracture per SD decrease in BMD was highest in black men (hip aBMD: HR = 2.04, 95% CI = 1.03, 4.04; vertebral TrvBMD: HR = 3.00, 95% CI = 1.29, 7.00) and lowest in white men (hip aBMD: HR = 1.23, 95% CI = 0.85, 1.78; vertebral TrvBMD: HR = 1.06, 95% CI = 0.73, 1.54). Adjusted for age, sex, and race, each SD decrease in hip aBMD was associated with a 1.67-fold (95% CI = 1.36, 2.07) greater risk of fracture, and each SD decrease in vertebral TrvBMD was associated with a 1.47-fold (95% CI = 1.18, 1.82) greater risk. Combining measurements of hip aBMD and vertebral TrvBMD did not improve fracture prediction.

CONCLUSIONS

Low BMD measured by either spine QCT or hip DXA predicts non-spine fracture in older black and white women and black men. Vertebral TrvBMD is not a stronger predictor than hip aBMD of non-spine fracture.

DXA estimates of vertebral volumetric bone mineral density in children: potential advantages of paired posteroanterior and lateral scans

Dual-energy X-ray absorptiometry (DXA) estimates of areal bone mineral density (BMD) are confounded by bone size in children. Two strategies have been proposed to estimate vertebral volumetric BMD: (1) bone mineral apparent density (BMAD) is based on the posteroanterior (PA) spine scan; (2) width-adjusted bone mineral density (WABMD) is based on paired PA lateral scans. The objective of this study was to compare DXA estimates of vertebral bone mineral content (BMC), volume and volumetric BMD obtained from Hologic PA scans (Hologic, Inc., Bedford, MA) alone, and paired PA lateral scans in 124 healthy children, ages 4 to 20 yr. The PA scans were used to estimate bone volume (PA Volume) as (PA Area)1.5 and BMAD as [(PA BMC)/(PA Volume)]. Paired PA lateral scans were used to estimate width-adjusted bone volume (WA Volume) as [(pi/4)(PA width)(lateral depth)(vertebral height)] and WABMD as [(lateral BMC)/(WA Volume)]. Generalized estimating equations were used to compare the relationship between scan type (PA vs. paired PA lateral) and bone outcomes, and the effects of height and maturation on this relationship. The estimates of BMC and volume derived from PA scans and paired PA lateral scans were highly correlated (r>0.97); WABMD and BMAD were less correlated (r=0.81). The increases in BMC, volume, and volumetric BMD with greater height and maturation were significantly larger (all p<0.001) when estimated from paired PA lateral scans, compared with PA scans alone. The proportion of spine BMC contained within the vertebral body, versus the cortical spinous processes, increased significantly with age (p<0.001) from 28% to 69%. The smaller increases in bone measures on PA scans may have been due to magnification error by the fan beam as posterior tissue thickness increased in taller, more mature subjects, and the distance of the vertebrae from the X-ray source increased. In conclusion, paired Hologic PA lateral scans may increase sensitivity to growth-related increases in trabecular BMC and density in the spine, with less bias due to magnification error.

Advanced Imaging Assessment of Bone Quality

Noninvasive and/or nondestructive techniques can provide structural information about bone, beyond simple bone densitometry. While the latter provides important information about osteoporotic fracture risk, many studies indicate that bone mineral density (BMD) only partly explains bone strength. Quantitative assessment of macrostructural characteristics, such as geometry, and microstructural features, such as relative trabecular volume, trabecular spacing, and connectivity, may improve our ability to estimate bone strength. Methods for quantitatively assessing macrostructure include (besides conventional radiographs) dual X ray absorptiometry (DXA) and computed tomography (CT), particularly volumetric quantitative computed tomography (vQCT). Methods for assessing microstructure of trabecular bone noninvasively and/or nondestructively include high-resolution computed tomography (hrCT), microcomputed tomography (micro-CT), high-resolution magnetic resonance (hrMR), and micromagnetic resonance (micro-MR). vQCT, hrCT, and hrMR are generally applicable in vivo; micro-CT and micro-MR are principally applicable in vitro. Despite progress, problems remain. The important balances between spatial resolution and sampling size, or between signal-to-noise and radiation dose or acquisition time, need further consideration, as do the complexity and expense of the methods versus their availability and accessibility. Clinically, the challenges for bone imaging include balancing the advantages of simple bone densitometry versus the more complex architectural features of bone, or the deeper research requirements versus the broader clinical needs. The biological differences between the peripheral appendicular skeleton and the central axial skeleton must be further addressed. Finally, the relative merits of these sophisticated imaging techniques must be weighed with respect to their applications as diagnostic procedures, requiring high accuracy or reliability, versus their monitoring applications, requiring high precision or reproducibility.

Evaluation of bone mineral density of the lumbar spine in patients with beta-thalassemia major with dual-energy x-ray absorptiometry and quantitative computed tomography: a comparison study

Osteoporosis is a common, multifactorial cause of morbidity in patients with beta-thalassemia. The present study was performed to compare bone mineral density (BMD) results in the lumbar spine of thalassemic patients measured by both dual-energy x-ray absorptiometry (DEXA) and quantitative computed tomography (QCT), and to determine their correlations with the markers of bone turnover. BMD was measured in the lumbar spine of 13 regularly transfused patients with beta-thalassemia major by both DEXA and QCT. Blood and urine samples were obtained for the determination of biochemical and hormonal profiles. Both T-scores and Z-scores were higher when measured by QCT (T-score = -0.41 +/- 1.31, Z-score = -0.56 +/- 1.08, mean +/- SD) compared with the values given by DEXA (T-score = -2.57 +/- 0.88, Z-score = -2.32 +/- 1.11, P = 0.0005). In comparison to DEXA, QCT T-scores were more closely correlated with age (r = -0.19 vs. r = -0.70, P = 0.0068). Strong negative correlation was found between QCT values and age (r = -0.67, P = 0.01). In comparison to DEXA T-scores, QCT T-scores were more closely correlated with osteocalcin, urine N-telopeptide cross-links of type I collagen, and deoxypyridinoline, but without statistical significance. DEXA T-scores were better correlated only with urine C-terminal telopeptides of type I collagen, but again without statistical significance. These results imply that the two methods cannot be used interchangeably in assessing BMD in thalassemic patients. However, which one of these two techniques more precisely determines the overall strength of vertebrae in patients with beta-thalassemia remains to be investigated.

Adaptation of the Carter method to adjust lumbar spine bone mineral content for age and body size: application to children who were born preterm

In adults, the Carter method allows the separation of the lumbar spine bone mineral content (BMC) into its constituents; bone volume (BV) and volumetric density (bone mineral apparent density [BMAD]). However, this method is not widely used in pediatric studies and does not account for the effects of body habitus on bone mass. The aims of this study were to modify the Carter method for use in children by developing an approach that adjusts separately for age and body height, and to test whether lumbar spine bone mass is normal in children born who were born preterm. Twenty-five preterm-born children were matched to a term-born child. Lumbar spine bone mass was measured using dual-energy X-ray absorptiometry. The BV and BMAD were calculated. Z-scores based on age and height were calculated. The preterm group had reduced absolute height, weight, BMC, BV, and BMAD, and reduced height, weight, and BMC for their age. The BMC was appropriate for height. The BV was appropriate for age. The BMAD was reduced for age but appropriate for height. In preterm children, the major abnormality at the lumbar spine is a decrease in volumetric density; however, this decrease is proportional with their reduced stature, and we speculate that there is no reduction in the strength of the lumbar spine.

Application of the 1994 WHO classification to populations other than postmenopausal Caucasian women: the 2005 ISCD Official Positions

In 2003, the International Society for Clinical Densitometry (ISCD) developed Official Positions regarding the applicability of the World Health Organization (WHO) classification of bone mineral density to populations other than postmenopausal women. However, these prior Official Positions do not fully address bone mineral density reporting in females prior to menopause, men, and non-whites. During the 2005 ISCD Position Development Conference, members of the ISCD Expert Panel in conjunction with the ISCD Scientific Advisory Committee re-addressed these topics and, based upon stringent reviews of best available data, developed ISCD Official Positions that provide greater specificity and clarification with respect to the following: (1) the utility of the term 'osteopenia'; (2) utilization of T- and Z-scores for bone mineral density reporting; (3) when to apply the WHO densitometric classification; and (4) which normative database(s) should be used for non-white individuals. Briefly, the term "osteopenia" is retained, but 'low bone mass' or 'low bone density' is preferred. Z-scores, not T-scores, are preferred in females prior to menopause and males under age 50. In these individuals, a Z-score of -2.0 or lower is defined as "below the expected range for age" and a Z-score above -2.0 is "within the expected range for age." T-scores are preferred and the WHO classification is applicable for postmenopausal women and men age 50 and older. These Official Positions, rationale and evidence are discussed in the following report.

Estimated risk score for spine fracture in the specific bending activity of normal Taiwanese men and women

OBJECTIVE

To investigate the effects of biologic age, as well as chronologic age, on the vertebral ultimate load (strength) and risk score of vertebral fracture (Phi) between the genders.

SUMMARY OF BACKGROUND DATA

Previous studies have shown a good correlation between the biomechanical strength of vertebral bodies and measured bone mineral parameters, whereas other factors also contribute to the bone strength and risk of fractures. Combining multiple factors into a single assessment may provide more comprehensive and individualized estimations of the fracture risk. In this study, we applied the measured bone mineral content (BMC) and bone projection area of the second through the fourth lumbar vertebrae (L2-L4) to assess the biomechanical strength of lumbar vertebrae. In addition, we used the body segment model to estimate the load of the L3 vertebral body during a bending-forward activity, to then estimate the risk score (Phi) of vertebral compression fracture in healthy Chinese volunteers in Taiwan, and to analyze the effects of gender and age on the risk score (Phi).

METHODS

A total of 611 females and 235 males aged 22-80 years were included in this study. The anteroposterior BMC and projection area of lumbar spine were measured by a Norland XR-26 dual energy radiograph absorptiometer (Norland Corp., Ft. Atkinson, WI). The estimated ultimate strength (L) of lumbar spine was calculated from the regression equation using anteroposterior lumbar BMC and bone area according to Bassman et al (Paper presented at: 39th Annual Meeting of Orthopedic Research Society; February 1993; San Francisco, CA). The estimated spinal load (F) for a person bending over with back horizontal, either with hand free (F0), lifting a 20 kg weight (F20), or a 30 kg weight (F30), was calculated from a force diagram according to William and Lissner. Risk score (Phi) was defined as the quotient of F/L.

RESULTS

The results showed an age-related decrease of bone mineral density (P < 0.001) in both genders corrected for weight and height. Using the multiple linear regression analysis and analysis of covariance, Phi for F0, F20, and F30 increased significantly, with increasing age only in females (P < 0.0001), especially after menopause, but not in males. The Phi of postmenopausal females was significantly larger than those of younger females (i.e., F0 (Phi) 0.533 +/- 0.075 vs. 0.458 +/- 0.064, P < 0.001; F20 (Phi) 0.903 +/- 0.101 vs. 0.789 +/- 0.080, P < 0.001; and F30 (Phi) 1.087 +/- 0.117 vs. 0.954 +/- 0.090, respectively, P < 0.001). In females, the ultimate load of the spine and Phi began to decrease to a significant level since the fifth decade, whereas in the males, the similar trends occurred since the sixth decade. Comparing both genders, the F0 (Phi) was slightly yet significantly larger in the young males (< 50 years) than the premenopausal females with similar ages (P < 0.001), but older females had higher F0 (Phi) values than males older than 60 years. Moreover, the Phi increased more prominently in the postmenopausal females with the weight lifted. As a result, both F20 (Phi) and F30 (Phi) were significantly larger in females older than 50 years as compared to males with the similar ages (P < 0.001).

CONCLUSIONS

Our findings emphasize the importance of Phi, which considers BMC, bone size, body weight, body height, and weight lifted, for evaluating a more individualized risk of spine fracture in elderly men and postmenopausal women. The Phi increased more prominently with lifting weight and increased with aging only in the early postmenopausal females. The study showed that a combination of bone mass and anthropometric parameters provides a more individualized assessment of fracture risk than bone mineral density alone.

Bone density accumulation is not affected by brace treatment of idiopathic scoliosis in adolescent girls

Bracing for adolescent scoliosis has been postulated to cause permanent loss of bone mass and to predispose to adult osteoporosis. To determine whether brace use affects the rate of bone accretion with growth, the authors conducted a prospective study of 52 girls with adolescent idiopathic scoliosis. Dual-energy x-ray absorptiometry (DEXA) showed a significant increase in spinal bone mineral density (BMD) over a 1-year period of brace wear. BMD correlated with measures of growth and pubertal status, but not average daily brace wear or severity of scoliosis. The annual rate of bone density accumulation was similar to reported normal values. The annual rate of change of volumetric bone density increased only slightly during the study period, suggesting that most of the change in BMD with time reflects growth in the dimensions of the spine. Brace treatment does not appear to inhibit bone density accumulation in girls with adolescent idiopathic scoliosis.

Three-dimensional X-ray absorptiometry (3D-XA): a method for reconstruction of human bones using a dual X-ray absorptiometry device

Three-dimensional accurate evaluation of the geometry of the proximal femur may be helpful for hip fracture risk evaluation. The purpose of this study was to apply and validate a stereo-radiographic 3D reconstruction method of the proximal femur, using contours identification from biplanar DXA images. Twenty-five excised human proximal femurs were investigated using a standard DXA unit. Three-dimensional personalized models were reconstructed using a dedicated non-stereo corresponding contours (NSCC) algorithm. Three-dimensional CT-scan reconstructions obtained on a clinical CT-scan unit were defined as geometric references for the comparison protocol, in order to assess accuracy and reproducibility of the 3D stereo-radiographic reconstructions. The precision of a set of 3D geometric parameters (femoral-neck axis length, mid-neck cross-section area, neck-shaft angle), obtained from stereo-radiographic models was also evaluated. This study shows that the NSCC method may be applied to obtain 3D reconstruction from biplanar DXA acquisitions. Applied to the proximal femur, this method showed good accuracy as compared with high-resolution personalized CT-scan models (mean error = 0.8 mm). Moreover, precision study for the set of 3D parameters yielded coefficients of variation lower than 5%. This is the first study providing 3D geometric parameters from standard 2D DXA images using the NSCC method. It has good accuracy and reproducibility in the present study on cadaveric femurs. In vivo prospective studies are needed to evaluate its discriminating potential on hip fracture risk prediction.

Lebanese guidelines for osteoporosis assessment and treatment: who to test? What measures to use? When to treat?

With the demographic explosion of the population worldwide, the human, social, and economic costs of osteoporosis will continue to rise. It is estimated that the magnitude of the problem might be even larger in developing countries, including those in the Middle East. Although several organizations and countries have developed or adapted guidelines to their local needs, as of today there are no guidelines for osteoporosis assessment in the Middle East. In April 2002, a panel of osteoporosis experts met and discussed practice guidelines for osteoporosis assessment and treatment in Lebanon. The process, which involved an overview of international guidelines as well as local data on osteoporosis, resulted in a draft for Lebanese guidelines that addressed three main questions: "Who to test?" "What measures to use?" and "When to treat?". Representatives from five major Lebanese societies (Endocrinology, Rheumatology, Orthopedics, Obstetrics and Gynecology, and Radiology) subsequently reviewed, discussed, and officially endorsed the guidelines after revisions. The Lebanese guidelines were also endorsed by the Eastern Mediterranean branch of the World Health Organization.

Apparent bone mineral density estimated from DXA in healthy men and women

The aim of this study was to measure bone mineral density (BMD) in healthy people and examine the influence of age, anthropometry, and postmenopause on calculated bone mineral apparent density (BMAD). The study included 541 healthy subjects (249 men and 292 women), aged 20 to 79 years. Anthropometric measurements included height, weight, and body mass index (BMI). Bone mineral content (BMC) and areal BMD were measured at the lumbar spine and proximal femur, using dual-energy X-ray absorptiometry (DXA). The calculation of volumetric density relied on the formula BMAD=BMD/ square root BA (where BA = bone area). Association between densitometric parameters and age, height, weight, and postmenopause was analyzed with multiple regression. BMC and BMD decreased with age, especially in postmenopausal women. The average annual bone loss in spine was 0.2% in both sexes, whereas femur loss was 0.5% in men and 0.3% in women. Bone area slightly increased with age in both sexes, and BMD loss after the age of 50 could be attributed to bone area increase. To minimize the effect of bone size on bone density, volumetric density and areal density were regressed to age, anthropometry, and postmenopause. Age and postmenopause were significantly associated with BMD and BMAD in the spine and femur. Furthermore, BMD showed a stronger association with height and weight than BMAD, in both regions. Weaker association of body height and weight with BMAD than with BMD suggests that BMD depends on the bone size and body size and that the different BMDs could be the consequence of the difference in those parameters.

Bone densitometry in premenopausal women: synthesis and review

Bone loss prior to menopause is being increasingly identified in women. Clearly, low bone mineral density (BMD) is a significant risk factor for fracture in the estrogen-deficient female postmenopause. The significance of low bone density prior to menopause needs to be addressed. Low bone density in the premenopausal female may reflect attainment of a lower peak bone mass. It may also be secondary to progressive bone loss following achievement of peak bone density. The etiology of low bone density in the premenopausal female needs to be clarified with meticulous exclusion of secondary causes of bone loss. Menstrual status is an important determinant of peak bone mass as well as the development of bone loss in women prior to the onset of menopause. Subclinical decreases in circulating gonadal steroids may be associated with a lower peak bone mass as well as progressive bone loss in otherwise reproductively normal women. Elevations of follicle-stimulating hormone (FSH) of greater than 20 miu/L are associated with evidence of increased bone turnover marker activity and correlate with progressive bone loss in perimenopausal women. This transitional period requires further study with respect to the magnitude of bone loss experienced and the potential benefits of antiresorptive therapy. Detailed assessment of menstrual status is necessary in the evaluation of low bone density in premenopausal women. The majority of the cross-sectional and longitudinal studies completed evaluating BMD in the premenopausal years suggest that minimal bone loss does occur prior to menopause after attainment of peak bone mass. The magnitude of premenopausal bone loss, however, is controversial and may be site-dependent. More rapid rates of bone loss are seen in the transitional period beginning 2-3 yr prior to the onset of menopause. Prospective data are needed to understand further the relationship between BMD and fracture in the premenopausal period. Women with steroid-induced bone loss as well as other secondary causes of osteoporosis respond to antiresorptive therapy with documented improvements in BMD. Biomarkers can identify perimenopausal women with increased bone turnover. Lifestyle modification can improve BMD in the pre- and the perimenopausal period. Antiresorptive therapy has not been evaluated in pre- or perimenopausal women with low BMD in the absence of secondary causes of osteoporosis. As new treatment options are evaluated and become available, biomarker assessment may be of value in identifying women at risk of fracture.

Bone density in survivors of childhood cancer

Advances in combination chemotherapy, radiation therapy, surgery, and bone marrow transplantation have resulted in markedly improved survival rates for many children with cancer. Advancements in therapy, however, have led to new concerns, namely long-term consequences of effective treatments. Young adult and adult survivors of childhood cancer are at risk for a number of disorders related to therapy. Specifically, the young adult who has survived cancer, attendant treatments, and their complications is at risk for factors that can lead to suboptimal acquisition of peak bone mass. These factors include chronic illness, nutritional deficiencies, limited physical activity, and treatment with glucocorticoids, multiagent chemotherapy, and radiation. The long-term adverse effects of these therapies on endocrine systems, especially sex steroid and growth hormone deficiencies, are additional risk factors for some patients. After a brief review of the processes associated with acquisition of peak bone mass in the young adult, this article examines the impact of cancer and cancer therapy on bone mineral density in survivors of childhood cancer.

Effects of projective bone area size of the spine on bone density and the diagnosis of osteoporosis in healthy pre-menopausal women in China

The aim of this study was to understand the effects of projective bone area (BA) size of the spine on bone density and the diagnosis of osteoporosis. Measurements of BA, bone mineral content (BMC), areal bone density (aBMD) and volumetric bone density (vBMD) at the posteroanterior (PA) lumbar spine (vertebrae L2-L4) followed by a paired PA/lateral spine (L2-L4) were made using a dual-energy X-ray absorptiometry (DXA) fan-beam bone densitometer (Hologic QDR 4500A) in 1436 healthy pre-menopausal women aged from 20 to 56-years-old. At the PA and lateral lumbar spine, there was a significant positive correlation between BA and BMC (r=0.762 and 0.762, p=0.000) and aBMD (r=0.370 and 0.352, p=0.000), but not vBMD (r=0.000 and 0.102, p=0.813 and 0.063). When BA at the PA spine changed by one standard deviation (SD), BMC and aBMD correspondingly changed by 12.6% and 4.3% on the basis of their respective means while vBMD indicated no change. When a variation of 1 SD was observed in BA at the lateral spine, BMC, aBMD and vBMD correspondingly changed by 13.8%, 4.4% and 1.73% on the basis of their respective means. Through an intercomparison among large, intermediate and small BA groups, significant differences were found in the means of subject's height, weight, BMC and aBMD at the PA and lateral spine as well as the detection rate of osteoporosis by aBMD (p=0.000). Detection rates of osteoporosis by aBMD at the PA, lateral spine and vBMD in healthy pre-menopausal women aged from 40 years to 56 years were 4.5%, 16.4% and 9.7%, respectively, in the small BA group; 1.3%, 6.4% and 7.3%, respectively, in the intermediate BA group; and 0, 0 and 5.5%, respectively, in the large BA group. No significant differences were found in the detection rates of osteoporosis by vBMD among the groups. The results of multiple linear regression revealed that the major factors influencing BA of the lumbar spine was height. In healthy pre-menopausal women of the same race and age, the BA size of the lumbar spine would have significant influence upon aBMD and the diagnosis of osteoporosis, i.e. the larger the BA, the greater the aBMD and the lower the osteoporosis detection rate while conversely, the smaller the BA, the smaller the aBMD and the higher the osteoporosis detection rate. Though vBMD does not change with BA sizes of the lumbar spine, it is a sensitive marker for diagnosing osteoporosis.