The correlation between dual-energy X-ray absorptiometry measures of bone density in the proximal femur and lumbar spine of children

 Objective. To assess the correlation between a pediatric patient’s proximal femur and lumbar spine bone mineral density (BMD) Z-scores, and the side-to-side difference between proximal femurs. Design. Three hundred and thirty-nine patients aged 2.2–17.0 years with an assortment of underlying conditions underwent dual-energy X-ray absorptiometry (DXA) measures of BMD in both proximal femurs and the lumbar spine. Results. Z-scores in the proximal femur and lumbar spine correlated highly (r=0.73, P=0.0001), but for individual patients the difference was often significant, and increased as BMD deviated further from normal. For patients with proximal femur Z-scores of 1 to –1 the mean difference between proximal femur and lumbar spine Z-scores was 0.5; with proximal femur Z-scores of less than –3 the mean difference was increased to 1.7. In conditions which symmetrically involve the lower extremities, the right and left proximal femur Z-scores differed on average by only 0.2. Conclusion. BMD measurements for pediatric patients are most easily interpreted by clinicians if converted to Z-scores, yet these are usually available only for the lumbar spine. Age-normalized BMD assessment at more than one site is necessary to provide a more reliable, complete assessment of bone mineral status in pediatric patients.     

Measurements of bone mineral density in the lumbar spine and proximal femur using lunar prodigy and the new pencil-beam dual-energy X-ray absorptiometry

Objective  

We evaluated the correlation of the absolute bone mineral density (BMD) values of the lumbar spine and standard sites of the proximal femur obtained from a Lunar Prodigy and the newly developed pencil-beam dual-energy X-ray absorptiometry (Dexxum).     

Cyclic oral phosphate and etidronate increase femoral and lumbar bone mineral density and reduce lumbar spine fracture rate over three years.

We have performed a study of the safety and efficacy of cyclic sequential oral phosphate, diphosphonate and calcium carbonate. Forty-two postmenopausal women with osteoporosis diagnosed by dual-photon absorptiometry were treated with a sequential cyclic regimen of oral phosphate for 3 days, etidronate for 2 wk, and then a calcium salt for 12 wk. This was repeated cyclically for 3 yr. They were rescanned after every two 101-day cycles. A control group of 20 patient receiving only the calcium salt was matched for age, time since menopause, race and sex. The group treated with cyclic phosphate, etidronate, and calcium regimen had 80% fewer fractures than the control group over 3 yr of follow-up. Significant response in halting bone mineral loss and increasing bone mineral density was seen in none of the controls but in 90% of treated patients' lumbar spine and 70%-80% of the three regions of the femoral neck examined.     

Estimation of lumbar spine bone mineral density by dual-energy X-ray absorptiometry: standard anteroposterior scans vs sub-regional analyses of whole-body scans

Dual-energy X-ray absorptiometry of the lumbar spine (anteroposterior (AP) L(1)-L(4) DXA) is one of the standards for testing bone density (BMD). Whole-body (WB) DXA scanning allows analysis of the L-spine (WB-LS). The objective of this study was (i) to predict the AP L(1)-L(4) BMD from the WB-LS BMD, and (ii) to compare WB and AP L(1)-L(4) T-scores. 132 women participated in the study (age, 50.84+/-9.69 years; range, 21-74 years). AP L(1)-L(4) BMD was measured on a Hologic QDR 4500-A densitometer, and was followed by a WB scan. Linear regression analyses and curve estimations were performed for area, bone mineral content (BMC), BMD and T-scores. Precision errors for BMD from AP scans and WB-LS scans were 1.37% and 1.65%, respectively. The best linear correlations were found for BMD, followed by the T-scores (R = 0.882 and 0.871; p<0.001). A power model for BMC (R(2) = 0.630) and a model S for BMD and the scanned area (R(2) = 0.841 and 0.539) were built. Discordant classification between AP L(1)-L(4) and WB T-scores was found in 12.73% and 19.09% cases, respectively. WB T-score cut-off values of -2.35 and -0.90 produced the best sensitivity-to-specificity ratio in the diagnosis of lumbar spine osteoporosis and low bone mass. In conclusion, WB-LS analysis may provide data for the indirect estimation of spinal BMD.     

Dual-energy x-ray absorptiometry: a precise method of measuring bone mineral density in the lumbar spine

We compared two methods of measuring spinal bone mineral content and density (BMC/BMD): conventional dual-photon absorptiometry (DPA) and a more recent method, dual-energy x-ray absorptiometry (DEXA). The clinical usefulness of both methods was compared in the measurement of BMC in the forearm. DEXA had a long-term in vivo precision of 1% which was significantly better than that of DPA. Changes in the distribution of fatty tissue influenced the accuracy of the two spinal methods in different ways. Forearm BMC discriminated between the bone mass of early and late postmenopausal women to the same degree as DPA and DEXA. The variability in the response to estrogen treatment and placebo was much lower with DEXA and forearm BMC than with DPA. We conclude that DEXA provides a fast and precise measurement of spinal BMC/BMD. The accuracy remains to be evaluated for in vivo studies.     

Normative data for lumbar spine bone mineral content in children: influence of age, height, weight, and pubertal stage

In 136 normal growing children between the ages of 1 and 18 yr, bone mineral content (BMC) at the level of the lumbar spine (L2-L4) was determined with a commercial dual-photon absorptiometer. BMC was calculated as BML (BMC per unit length) and BMD (BMC per unit surface). The mean lumbar spine BML of the studied children (2.53 +/- 0.86 gHA/cm) was significantly lower than the spinal mineral content of adults (4.26 +/- 0.57 gHA/cm). No sex difference existed in lumbar spine BMC. BML as well as BMD were highly dependent on age, body height, and body weight. During the prepubertal years, BML and BMD increased in a fairly rectilinear pattern. During puberty, BMC increased more rapidly: 40% for BMD and 77% for BML. For the entire group, the increase in BMC with age, height, and weight was best predicted by an exponential regression line analysis.     

Bone mineral density reference values in the normal female and male population of Izmir,Turkey

In this study we aimed to establish the dual-energy X-ray absorptiometry (DXA) bone mineral density (BMD) reference values of healthy Turkish women and men residing in Izmir, western Turkey. We examined 347 women and 119 men (age range 20-80 years) who did not have any known risk factor that might affect bone mass. The BMD measurements were performed by Hologic QDR 4500 W Elite DXA instrument from the lumbar spine (L1-L4) and non-dominant hip. In women the mean BMD (g/cm(2))+/-standard deviation (SD) of the normal reference group between 20 and 39 years of age was 0.963+/-0.121 g/cm(2) in the lumbar spine and 0.891+/-0.119 g/cm(2) in total femoral region. The percentages of annual and total BMD losses in women between 30 and 80 years of age were 0.74 and 29% at spinal level and 0.65 and 26% in femoral region, respectively. The average BMD of the normal men's group between 20 and 39 years of age was 0.996+/-0.111 g/cm(2) in the lumbar spine and 1.025+/-0.110 g/cm(2) in femoral region. The percentages of annual and total BMD losses were 0.33 and 13% at spinal level and 0.50 and 20% in femoral region, respectively. In conclusion, like the values reported from mid-Anatolian region of Turkey, the BMD values of Turkish women and men residing in Izmir, western Anatolia, are also lower than in most European countries with regard to US and preinstalled Hologic values.     

CT of the middiaphyseal femur: cortical bone mineral density and relation to porosity

PURPOSE: To determine whether computed tomography (CT) can be used to quantify age- and site-related changes in cortical bone mineral density (cBMD) at the middiaphyseal femur and whether cBMD differences are related to intracortical porosity. MATERIALS AND METHODS: Cortical bone specimens from 163 femurs were studied with CT and microradiography. Femurs were from 77 males and 86 females in a white anthropologic collection covering a broad age spectrum. In each sample, the cBMD was measured in the entire cortical width and in periosteal, midcortical, and endosteal subregions of interest. Age- and site-related changes in cBMD were tested for significance by using a two-way analysis of variance for both sexes. By using linear regression, cBMD was compared with porosity in the entire cortical width and in each subregion. RESULTS: There were significant age-related differences in cBMD (P <.001 in females, P =.008 in males). In addition, cBMD values were significantly different between the three cortical subregions (P <.001 for both sexes), decreasing from the periosteum to the midcortex to the endosteum. The cBMD values were closely related to porosity, and porosity contributed to 71.6% of the variance in cBMD in the overall population. CONCLUSION: CT is effective in the measurement of age- and site-related changes in cBMD. Decreases in cBMD are closely correlated with increased cortical porosity.     

Bone mineral density reference values in the normal female and male population of İzmir, Turkey

In this study we aimed to establish the dual-energy X-ray absorptiometry (DXA) bone mineral density (BMD) reference values of healthy Turkish women and men residing in İzmir, western Turkey. We examined 347 women and 119 men (age range 20–80 years) who did not have any known risk factor that might affect bone mass. The BMD measurements were performed by Hologic QDR 4500 W Elite DXA instrument from the lumbar spine (L1–L4) and non-dominant hip. In women the mean BMD (g/cm²)±standard deviation (SD) of the normal reference group between 20 and 39 years of age was 0.963±0.121 g/cm² in the lumbar spine and 0.891±0.119 g/cm² in total femoral region. The percentages of annual and total BMD losses in women between 30 and 80 years of age were 0.74 and 29% at spinal level and 0.65 and 26% in femoral region, respectively. The average BMD of the normal men's group between 20 and 39 years of age was 0.996±0.111 g/cm² in the lumbar spine and 1.025±0.110 g/cm² in femoral region. The percentages of annual and total BMD losses were 0.33 and 13% at spinal level and 0.50 and 20% in femoral region, respectively. In conclusion, like the values reported from mid-Anatolian region of Turkey, the BMD values of Turkish women and men residing in İzmir, western Anatolia, are also lower than in most European countries with regard to US and preinstalled Hologic values. Electronic Publication     

Effect of Paget's disease of bone on areal lumbar spine bone mineral density measured by DXA, and density of cortical and trabecular bone measured by quantitative CT

Although bone density may be increased in bone that is affected by Paget's disease, density changes in cortical and trabecular bone and the effect on bone that is apparently unaffected by Paget's disease are relatively unexplored. We have investigated 81 vertebrae (28 affected, 53 unaffected) in 27 patients with Paget's disease, by dual X-ray absorptiometry (DXA) and by quantitative CT (QCT) bone density measurements of trabecular and cortical bone. DXA bone density was high (mean z-score = 1.62, p < 0.001) in vertebrae affected by Paget's disease, but not significantly different from normal in unaffected vertebrae (mean z-score = 0.07, ns). Mean QCT z-score in Paget's vertebrae was 2.07 (p = 0.009) for cortical bone and 1.37 (p = 0.008) for trabecular bone. DXA correlated with QCT cortical values in affected and unaffected bone (r = 0.8 and 0.56, respectively), and with QCT trabecular values (r = 0.72 and 0.48, respectively). There was no significant difference in the slopes for the correlations in affected or unaffected bone. Cortical QCT values are underestimated in Paget's disease compared with physical measurements of density, owing to the computer algorithm used. High DXA values may alert to the possibility of Paget's disease, especially if the value deviates from the expected normal sequence in lumbar vertebrae. Osteoporotic vertebrae may be overlooked if the average value of bone mineral density is taken in the lumbar spine without reviewing each vertebra.     

Measurement of lumbar spine bone mineral: a comparison of dual photon absorptiometry and computed tomography

A comparison of computed tomography (CT) and dual photon absorptiometry (DPA) in the measurement of spinal bone mineral was made in 44 subjects of whom 26 had vertebral crush fractures. Although CT measures only trabecular bone within the vertebral body whilst DPA measures the whole vertebral segment, a good correlation was observed (r = 0.80) when these quantities were expressed in dimensionally similar units. Trabecular bone in the distal radius measured by CT correlated less well with vertebral CT (r = 0.65). Cortical bone in the radius correlated poorly with the spinal DPA measurement (r = 0.38).     

Relationship between body composition, body mass index and bone mineral density in a large population of normal, osteopenic and osteoporotic women

Purpose

The knowledge of factors modulating the behaviour of bone mass is crucial for preventing and treating osteoporotic disease; among these factors, body weight (BW) has been shown to be of primary importance in postmenopausal women. Nevertheless, the relative effects of body composition indices are still being debated. Our aim was to analyze the relationship between body mass index (BMI), fat and lean mass and bone mineral density (BMD) in a large population of women. Moreover, this study represents a first important report on reference standard values for body composition in Italian women.

Materials and methods

Between 2005 and 2008, weight and height of 6,249 Italian women (aged 30?C80 years) were measured and BMI was calculated; furthermore BMD, bone mineral content, fat and lean mass were measured by dual-energy X-ray absorptiometry. Individuals were divided into five groups by decades (group 1, 30.0?C39.9; group 2, 40.0?C49.9; group 3, 50.0?C59.9; group 4, 60.0?C69.9; group 5, 70.0?C79.9). Differences among decades for all variables were calculated using a one-way analysis of variance (ANOVA) and Bonferroni test by the SPSS programme.

Results

Mean BW was 66.8±12.1 kg, mean height 159.1±6.3 cm and mean BMI 26.4±4.7 kg/m². According to BW and BMI, there was an increase of obesity with age, especially in women older than 50 years (p<0.001). Lean mass increased until 50 years of age but significantly decreased after this age (p<0.001). The percentage of osteopenia and osteoporosis in the examined population was 43.0% and 16.7%, respectively.

Conclusions

Our data show that obesity significantly decreased the risk for osteoporosis but did not decrease the risk for osteopenia. It is strongly recommended that a strong policy regarding prevention of osteopenia and osteoporosis be commenced. An overall examination of our results suggests that both fat and lean body mass can influence bone mass and that their relative effect on bone could be modulated by their absolute amount and ratio to total BW.     

Bone densitometry using computed tomography. Part I: selective determination of trabecular bone density and other bone mineral parameters. Normal values in children and adults.

Gamma-ray computed tomography (gamma-ray CT), using a special purpose scanner, enables in-vivo quantitative analysis of bone mineralization. Trabecular bone density (TBD), the relative amount of compact bone (bone density, BD) and the total absorption (TA) for a cross-section of the radius are determined from measurements of local linear absorption coefficients. A preliminary study of normal children (n = 49) and adults (n = 34) indicated that TBD is independent of age and sex in the age range 4 to 40 years. DB remains constant throughout childhood but increases after puberty in both women and men. TA is higher for adults than for children, and also higher for men than for women. A correlation between TA and parameters relating to body size indicates a relationship between body weight and bone mass.     

Bone mineral density of the lumbar spine by dual photon absorptiometry: age-related regression in normal Japanese subjects and fracture threshold in osteoporotics

The bone mineral density (BMD) of the lumbar spine was determined by DPA in 280 normal Japanese volunteers and 11 osteoporotic women with compression fractures. In women, bone loss started from the mid thirties and accelerated after the age of 50 years at the rate of 0.75% (0.0074 g/cm2) per year. In men, bone loss started from the mid twenties and occurred linearly at the rate of 0.30% (0.0032 g/cm2). The overall diminutions in vertebral BMD throughout life in men and women were 13.0% and 24.3%, respectively. The mean vertebral BMD of the osteoporotic women with recent compression fractures was 37.5% lower than that of age-matched controls. The 90th percentile for vertebral BMD in this group was 0.584 g/cm2. By the age of 80 years, approximately one-fifth of normal Japanese women have BMD values less than this.     

Whole-body bone mineral content, lean body mass, and fat mass measured by dual-energy X-ray absorptiometry in a population of normal Canadian children and adolescents.

Measurements of body composition have evident value in evaluating growing children and adolescents, and dual-energy X-ray absorptiometry (DXA) is a tool that provides accurate measurements of whole-body bone mineral content (WBBMC), lean body mass (LBM), and fat mass (FM). To interpret such measurements in the context of ill health, normative values must be available. Such information could be expected to be regionally specific because of differences in ethnic, dietary, and physical activity determinants. In this study, DXA was performed with Hologic densitometers in normal girls (n = 91) and boys (n = 88) between 3 and 18 years of age. The derivation of normal ranges is presented for boys and girls. The correlation of the sum of WBBMC, LBM, and FM with directly measured body weight was almost perfect (r > 0.997). As expected, FM and body mass index correlated strongly. The normal values for WBBMC, LBM, and FM from this study are compared with other Canadian data and with published normative data from Argentina and the Netherlands, all of which use different densitometers. The results of this study allow the calculation of z scores for each facet of body composition and facilitate the use of DXA to report routine evaluations of body composition in children and adolescents.