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Biomedical subjects

T F Lang

Publications and source records attributed to T F Lang.

At least 19 recordsLinked to original sources
PubMed2006

Influence of anthropometric parameters and bone size on bone mineral density using volumetric quantitative computed tomography and dual X-ray absorptiometry at the hip.

PURPOSE: To evaluate the influence of anthropometric parameters (age, height, and weight) and bone size on bone mineral density (BMD) using volumetric quantitative computed tomography (QCT) and dual X-ray absorptiometry (DXA) in a group of elderly women. MATERIAL AND METHODS: BMD values were obtained with DXA and QCT at the spine and hip in a cohort of 84 elderly women (mean age 73 +/- 6 years). QCT measures included trabecular, integral, and cortical BMD assessed at the hip and spine as well as cross-sectional areas of the mid-vertebrae and proximal femora. Spinal integral and femoral neck BMD measures were well matched to the regions of bone quantified on anteroposterior (AP) spine DXA and the femoral neck region of hip DXA. RESULTS: When QCT parameters were linearly regressed against body height and weight, only the relationships with weight were found to be statistically significant. Except for cortical BMD at the femoral neck, all BMD and geometric parameters measured from both DXA and QCT showed statistically significant associations with body weight (r2 = 0.4, 0.0001 < P < 0.02). The strongest associations with weight were found for DXA Neck (DXA_NECK) and DXA lumbar spine (DXA_LSP) (r2 = 0.4, P < 0.0001). CONCLUSION: The relationship of DXA BMD is stronger than QCT BMD with body weight and it encompasses the response of both bone size and density to increasing body mass.

Absorptiometry, Photon↗
PubMed2005

Effect of spinal degenerative changes on volumetric bone mineral density of the central skeleton as measured by quantitative computed tomography.

PURPOSE: To evaluate the impact of degenerative changes due to osteoarthritis (OA) at the spine on volumetric bone mineral density (BMD) as measured by volumetric quantitative computed tomography (vQCT). MATERIAL AND METHODS: Eighty-four elderly women (mean age 73 +/- 6 years), comprising 33 with vertebral fractures assessed by radiographs and 51 without vertebral fractures, were studied. Trabecular, cortical, and integral BMD were examined at the spine and hip using a helical CT scanner and were compared to dual X-ray absorptiometry (DXA) measurements at the same sites. OA changes visible on the radiographs were categorized into two grades according to severity. Differences in BMD measures obtained in the two groups of patients defined by OA grade using the described radiologic methods were compared using analysis of variance. Standardized difference (effect sizes) was also compared between radiologic methods. RESULTS: Spinal trabecular BMD did not differ significantly between OA grade 0 and OA grade 1. Spinal cortical and integral BMD measures showed statistically significant differences, as did the lumbar spine DXA BMD measurement (13%, P = 0.02). The QCT measurements at the hip were also higher in OA 1 subjects. Femoral trabecular BMD was 13-15% higher in OA grade 1 subjects than in OA grade 0 subjects. The cortical BMD measures in the CT_TOT_FEM and CT_TROCH ROI's were also higher in the OA 1 subjects. The integral QCT BMD measures in the hip showed difference between grades OA 1 and 0. The DXA measurements in the neck and trochanter ROI's showed smaller differences (9 and 11%, respectively). There were no statistically significant differences in bone size. CONCLUSION: There is no evidence supporting that trabecular BMD measurements by QCT are influenced by OA. Instead, degenerative changes have an effect on both cortical and integral QCT, and on DXA at the lumbar spine and the hip. For subjects with established OA, assessment of BMD by volumetric QCT may be suggested.

Absorptiometry, Photon↗
PubMed2004

Iatrogenic copper deficiency following information and drugs obtained over the Internet.

We report the case of a 56-year-old woman with a 7-year history of metastatic cancer who presented with severe copper deficiency following self-treatment with the copper-chelating agent tetrathiomolybdate. This compound was used with the aim of inhibiting tumour angiogenesis and was obtained from the USA by placing an order on the internet. The patient exhibited severe neutropenia as her serum copper concentration fell from 19.8 micromol/L to 3.3 micromol/L and her caeruloplasmin concentration from 35 mg/dL to 4 mg/dL.

Copper↗
PubMed2003

Daily treatment with parathyroid hormone is associated with an increase in vertebral cross-sectional area in postmenopausal women with glucocorticoid-induced osteoporosis.

Daily treatment with hPTH (1-34) is associated with a significant increase in bone formation which results in large gains in lumbar spine bone mass. However, bone formation is known to occur on trabecular, endocortical and periosteal surfaces. The purpose of this study was to determine whether daily treatment with hPTH (1-34) for 1 year was associated with a change in vertebral cross-sectional area, or vertebral size, as measured by serial quantitative computed tomography scans. Fifty-one postmenopausal women treated chronically with both glucocorticoids and hormone replacement therapy (HRT) were randomized to either daily hPTH (1-34) for 1 year and HRT or to a control group treated with only HRT. Measurements of bone density of the spine were obtained every 6 months by dual-energy X-ray absorptiometry (DXA) and annually by QCT of the L1 and L2 vertebrae. Vertebral cross-sectional area (VCSA) was obtained from the QCT scans. In addition, we estimated the vertebral compressive strength (VSFOM, g(2)/cm(4) = trabecular BMD(2) x VCSA). After 1 year of hPTH (1-34) treatment, VCSA increased 4.8% (p < 0.001), and 1 year after treatment was discontinued VCSA was still 2.6% higher than the baseline value (p < 0.05). The control group had no change in VCSA. In addition, estimated vertebral compressive strength increased more than 200% over baseline levels in the hPTH (1-34) treatment group and no change was observed in the control group. In summary, daily treatment with hPTH (1-34) for 1 year increased vertebral size as measured by VCSA and this increase was maintained after hPTH (1-34) was discontinued. Since vertebral fracture risk is related to both bone size and bone mass, we cautiously speculate that the increase in vertebral size associated with hPTH (1-34) treatment is at least partially responsible for increased vertebral bone strength and reduction of fracture risk associated with this therapy in postmenopausal osteoporosis.

Absorptiometry, Photon↗
PubMed2002

Measurement of bone mineral density at the spine and proximal femur by volumetric quantitative computed tomography and dual-energy X-ray absorptiometry in elderly women with and without vertebral fractures.

The goal of this study was to determine the effect of vertebral fracture status on trabecular bone mineral density (BMD) measurements obtained in the proximal femur and spine by helical volumetric quantitative computed tomography (vQCT). The study population consisted of 71 Italian women (average age 73 +/- 6) years. This group included 26 subjects with radiographically confirmed atraumatic vertebral fractures and 45 controls. The subjects received helical CT scans of the L1 and L2 vertebral bodies and the hip. The three-dimensional CT images were processed using specialized image analysis algorithms to extract measurements of trabecular, cortical, and integral BMD in the spine and hip. To compare the vQCT results with the most widely used clinical BMD measurement, dual X-ray absorptiometry (DXA) scans of the anteroposterior (AP) spine and proximal femur were also obtained. The difference between the subjects with vertebral fractures and the age-matched controls was computed for each BMD measure. All BMD measurements showed statistically significant differences, which ranged from 7% to 22% between subjects with fractures and controls. Although, given our small sample size, we could not detect statistically significant differences in discriminatory power between BMD techniques, integral BMD of the spine measured by vQCT and DXA tended to show stronger associations with fracture status (0.001 < p < 0.004). Measurements by QCT and DXA at the hip were also associated with vertebral fracture status, although the association of DXA BMD with fracture status was explained largely by differences in body weight between subjects with vertebral fractures and controls.

Absorptiometry, Photon↗
PubMed2001

Bicarbonate and fluid secretion evoked by cholecystokinin, bombesin and acetylcholine in isolated guinea-pig pancreatic ducts.

1. HCO3- secretion was investigated in interlobular duct segments isolated from guinea-pig pancreas using a semi-quantitative fluorometric method. Secretagogue-induced decreases in intracellular pH, following blockade of basolateral HCO3- uptake with a combination of amiloride and DIDS, were measured using the pH-sensitive fluoroprobe BCECF. Apparent secretory HCO3- fluxes were calculated from the initial rate of intracellular acidification. 2. In the presence of HCO3-, stimulation with secretin (10 nM) or forskolin (5 microM) more than doubled the rate of intracellular acidification. This effect was abolished in the absence of HCO3-. It was also abolished in the presence of HCO3- when DIDS and NPPB were applied to the luminal membrane by microperfusion. We therefore conclude that the increase in acidification rate is a useful index of secretagogue-induced HCO3- secretion across the luminal membrane. 3. Secretin, cholecystokinin (CCK) and bombesin each stimulated HCO3- secretion in a dose-dependent fashion. They evoked comparable maximal responses at about 10 nM and the EC50 values were 0.5 nM for secretin, 0.2 nM for CCK and 30 pM for bombesin. Acetylcholine (ACh) was also effective, with a maximum effect at 10 microM. 4. The stimulatory effect of CCK was blocked completely by the CCK1 receptor antagonist devazepide but not by the CCK2 receptor antagonist L365,260. The CCK analogue JMV-180 (Boc-Tyr(SO3H)-Nle-Gly-Trp-Nle-Asp-phenylethyl ester), which is an agonist of the high-affinity CCK1 receptor but an antagonist of the low-affinity receptor, also stimulated HCO3- secretion but with a smaller maximal effect than CCK. JMV-180 partially inhibited the response to a high concentration of CCK but not to a lower concentration, suggesting that both high- and low-affinity states of the CCK1 receptor evoke HCO3- secretion. 5. The stimulatory effect of bombesin was blocked completely by the gastrin-releasing peptide (GRP) receptor antagonist D-Phe6-bombesin(6-13)-methyl ester (BME) but not by the neuromedin B (NMB) receptor antagonist D-Nal-cyclo[Cys-Tyr-D-Trp-Orn-Val-Cys]-Nal-NH2 (BIM-23127). 6. Secretagogue-evoked fluid secretion was also examined using video microscopy to measure the rate of swelling of ducts whose ends had sealed during overnight culture. Secretin, CCK, bombesin and ACh all evoked fluid secretion with maximal rates of approximately 0.6 nl x min(-1) x mm(-2), and with concentration dependences similar to those obtained for HCO3- secretion. 7. We conclude that CCK, bombesin and ACh stimulate the secretion of a HCO3--rich fluid by direct actions on the interlobular ducts of the guinea-pig pancreas and that these responses are mediated by CCK1 receptors, GRP receptors and muscarinic cholinoceptors, respectively.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2001

Race and sex effects on the association between muscle strength, soft tissue, and bone mineral density in healthy elders: the Health, Aging, and Body Composition Study.

Two factors generally reported to influence bone density are body composition and muscle strength. However, it is unclear if these relationships are consistent across race and sex, especially in older persons. If differences do exist by race and/or sex, then strategies to maintain bone mass or minimize bone loss in older adults may need to be modified accordingly. Therefore, we examined the independent effects of bone mineral-free lean mass (LM), fat mass (FM), and muscle strength on regional and whole body bone mineral density (BMD) in a cohort of 2,619 well-functioning older adults participating in the Health, Aging, and Body Composition (Health ABC) Study with complete measures. Participants included 738 white women, 599 black women, 827 white men, and 455 black men aged 70-79 years. BMD (g/cm2) of the femoral neck, whole body, upper and lower limb, and whole body and upper limb bone mineral-free LM and FM was assessed by dual-energy X-ray absorptiometry (DXA). Handgrip strength and knee extensor torque were determined by dynamometry. In analyses stratified by race and sex and adjusted for a number of confounders, LM was a significant (p < 0.001) determinant of BMD, except in white women for the lower limb and whole body. In women, FM also was an independent contributor to BMD at the femoral neck, and both FM and muscle strength contributed to limb BMD. The following were the respective beta-weights (regression coefficients for standardized data, Std beta) and percent difference in BMD per unit (7.5 kg) LM: femoral neck, 0.202-0.386 and 4.7-5.9%; lower limb, 0.209-0.357 and 2.9-3.5%; whole body, 0.239-0.484 and 3.0-4.7%; and upper limb (unit = 0.5 kg), 0.231-0.407 and 3.1-3.4%. Adjusting for bone size (bone mineral apparent density [BMAD]) or body size BMD/height) diminished the importance of LM, and the contributory effect of FM became more pronounced. These results indicate that LM and FM were associated with bone mineral depending on the bone site and bone index used. Where differences did occur, they were primarily by sex not race. To preserve BMD, maintaining or increasing LM in the elderly would appear to be an appropriate strategy, regardless of race or sex.

Absorptiometry, Photon↗
PubMed2000

Advanced imaging of the macrostructure and microstructure of bone.

Noninvasive and/or nondestructive techniques are capable of providing more macro- or microstructural information about bone than standard bone densitometry. Although the latter provides important information about osteoporotic fracture risk, numerous studies indicate that bone strength is only partially explained by bone mineral density. Quantitative assessment of macro- and microstructural features may improve our ability to estimate bone strength. The methods available for quantitatively assessing macrostructure include (besides conventional radiographs) quantitative computed tomography (QCT) and volumetric quantitative computed tomography (vQCT). Methods for assessing microstructure of trabecular bone noninvasively and/or nondestructively include high-resolution computed tomography (hrCT), micro-computed tomography (muCT), high-resolution magnetic resonance (hrMR), and micromagnetic resonance (muMR). vQCT, hrCT and hrMR are generally applicable in vivo; muCT and muMR are principally applicable in vitro. Although considerable progress has been made in the noninvasive and/or nondestructive imaging of the macro- and microstructure of bone, considerable challenges and dilemmas remain. From a technical perspective, the balance between spatial resolution versus sampling size, or between signal-to-noise versus radiation dose or acquisition time, needs further consideration, as do the trade-offs between the complexity and expense of equipment and the availability and accessibility of the methods. The relative merits of in vitro imaging and its ultrahigh resolution but invasiveness versus those of in vivo imaging and its modest resolution but noninvasiveness also deserve careful attention. From a clinical perspective, the challenges for bone imaging include balancing the relative advantages of simple bone densitometry against the more complex architectural features of bone or, similarly, the deeper research requirements against the broader clinical needs. The considerable potential biological differences between the peripheral appendicular skeleton and the central axial skeleton have to be addressed further. Finally, the relative merits of these sophisticated imaging techniques have to be weighed with respect to their applications as diagnostic procedures requiring high accuracy or reliability on one hand and their monitoring applications requiring high precision or reproducibility on the other.

Animals↗
PubMed1998

Vertebral fracture assessment using the lateral scoutview of computed tomography in comparison with radiographs.

Semiquantitative vertebral fracture assessment was compared between lateral computed tomography (CT) scoutviews and conventional thoracolumbar spinal radiographs. Vertebral levels T4-L4 were assessed by both techniques in a group of 56 women (mean age 60 +/- 13 years). In order to compare inter- and intra-observer variabilities for the two techniques, the images were analyzed twice by two independent observers, and percentage agreement and kappa statistics were measured both between readings and between observers. Percentage agreement and kappa statistics were also used to quantify differences between techniques. In the CT scoutviews, noise and artifacts from overlying tissues in the thoracic spinal levels rendered 3.4% of the vertebrae unreadable for the first observer and 8.3% for the second observer. For the CT scoutviews the agreement between readings was 98.1%, 97.3% and 100% (kappa = 0.87, 0.83 and 1.0) on T4-L12, T4-12 and L1-4, respectively for the first observer, and 97.8%, 97.1% and 99.5% (kappa = 0.79, 0.73 and 0.92) for the second observer. For the lateral radiographs, the agreement between readings was 97.7%, 96.9% and 100% (kappa = 0.87, 0.85 and 1.0) on T4-L12, T4-12 and L1-4, respectively for the first observer, and 98.4%, 97.7% and 99.5% (kappa = 0.86, 0.82 and 0.95) for the second observer. The agreement between observers was 96.1%, 94.4% and 100% (kappa = 0.68, 0.58 and 1.0) on T4-L12, T4-12 and L1-4, respectively for the CT scoutviews and 96.8%, 95.9% and 99.0% (kappa = 0.79, 0.76 and 0.91) for the lateral radiographs. The inter-technique was 95.8%, 94.2% and 99.5% (kappa = 0.73, 0.68 and 0.95) on T4-L12, T4-12 and L1-4, respectively for the first observer and 95.6%, 94.2% and 99.0% (kappa = 0.64, 0.55 and 0.90) for the second observer, with the scoutview technique detecting, on average, 23% fewer fractures than the lateral radiographs. Although the vertebral fracture detection in lumbar spine is quite comparable to that of conventional radiographs, given its reduced sensitivity for vertebral fracture detection in thoracic spine, the lateral CT scoutview technique should not be substituted for conventional radiographs where diagnosis of all vertebral fractures is of primary importance.

Adult↗
PubMed1998

Image-based assessment of spinal trabecular bone structure from high-resolution CT images.

The goal of this study was to assess whether a high-resolution CT measure of trabecular bone structure can enhance the discrimination between subjects with or without a vertebral fracture and having overall low hip or spine bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA). Sixty-one women with low BMD by DXA (T-score < -2.5 at hip or spine) were examined. Twenty women had sustained a vertebral fracture. Quantitative CT (QCT) BMD and high-resolution CT spinal scans were performed on a whole-body CT scanner. For the high-resolution images (0.31 mm pixel, 1.5 mm thick slice), trabecular bone was segmented from marrow using an adaptive threshold, region growth and skeletonization step. From the processed image we measured the apparent trabecular bone fraction (BV/TV), apparent trabecular thickness (I.Th) and apparent trabecular spacing (I.Sp). We also assessed the connectivity of the marrow space using region growing to derive a mean (HA) and maximum (HM) hole size. Despite the fact that the study population was preselected to have a low BMD by DXA, QCT BMD was highly associated with (p < 0.005) with fracture status. All structural parameters were correlated (r approximately 0.64 to 0.79) with BMD with p < 0.003 and showed significant differences between the fracture and non-fracture group. However, except for HA, this difference did not remain significant after adjustment for BMD. When BMD and then HA was entered into a paired linear regression model to predict fracture outcome, HA contributed with p = 0.03 and BMD with p = 0.86. ROC analysis was applied and showed that HA, BMD, I.Th and I.Sp discriminated the two groups with areas of 0.76, 0.75, 0.71 and 0.68, respectively. These findings suggest that an assessment of vertebral trabecular structure from high-resolution CT images is useful in discriminating subjects with vertebral fractures and potentially useful for predicting future fractures.

Aged↗
PubMed1998

Anisotropy of the elastic modulus of trabecular bone specimens from different anatomical locations.

To associate the mechanical anisotropy of trabecular bone with the relationship between bone mineral density (BMD) and mechanical properties, 97 cubic specimens of human trabecular bone were imaged with computed tomography. Bone cubes from the spine, the calcaneus, the distal, and the proximal femur were tested multidirectionally to measure their compressive stiffness and to calculate their ratios of mechanical anisotropy. The ultimate strength was determined in a destructive test in cephalo-caudal (c-c) direction. Compressive stiffness was largest in the c-c direction for the specimens from the spine, as well as the distal and the proximal femur, but not the calcaneus. Anisotropy ratios in c-c direction were larger at the distal femur and the spine than in the proximal femur. The predictive power of BMD for the mechanical properties varied with anatomical location and strongly depended on the loading direction. While at the spine the c-c stiffness was highly correlated to BMD (r2 = 0.73), the perpendicular directions showed only modest correlations (r2 < 0.53). The correlations of mechanical properties with BMD were greatest at locations where the anisotropy was less pronounced (proximal femur) or rather uniform (spine). The data suggest that BMD can be most successfully applied to determine the mechanical properties in the principal loading direction, which from a clinical perspective may be most relevant.

Adult↗
PubMed1998

Assessment of bone mineral at appendicular sites in females with fractures of the proximal femur.

The prediction of hip fractures by measurements at remote sites or the improvement of predictive power by measurements at multiple sites could potentially increase the success of osteoporosis screening programs. In a cross-sectional study on 137 postmenopausal women, we tested the hypothesis that bone assessment at the hip, the forearm, and the tibia are independently associated with osteoporotic fractures of the hip. Bone mineral densities, geometric features, and ultrasound properties were determined with hip dual X-ray absorptiometry, forearm peripheral quantitative computed tomography (QCT), and tibia speed of sound measurement. While the odds ratios for fracture discrimination per standard deviation decrease ranged between 3 and 4 for measurements at the hip, they were only 1.8 at the forearm and 1.4 at the tibia. Measurements at the tibia or the forearm were neither independently associated with osteoporotic hip fractures (p > 0.05) nor could any combination of measurements significantly increase the power for the identification of fractures as measured with receiver operating curves. Women who sustained trochanteric fractures were characterized by a generalized loss of bone mineral. Cervical fractures were associated with a decrease of bone mineral density at the hip, but no significant alterations in bone mass or geometric properties were observed at the tibia or at the forearm. Fracture risk prediction at the hip is therefore preferably performed by measurements at the hip itself. Peripheral QCT at the distal radius and tibial ultrasound seem capable of depicting women with an increased risk for trochanteric but not for cervical fractures. The risk assessment appears not to be improved by including information of cortical or geometric properties of the forearm.

Absorptiometry, Photon↗
PubMed1998

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

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

Aluminum↗
PubMed1998

Trochanteric hip fracture: strong association with spinal trabecular bone mineral density measured with quantitative CT.

PURPOSE: To determine the discriminatory capability for hip fracture of trabecular and integral bone mineral density (BMD) measured with quantitative computed tomography (CT) of the spine. MATERIALS AND METHODS: Fifty-six women who had sustained hip fractures and 59 control subjects underwent volumetric quantitative CT of L1 and L2 and dual x-ray absorptiometry of the hip. BMD was measured in vertebral regions of interest that encompassed trabecular, cortical, and integral bone. Logistic regression analysis was applied to each BMD measure to derive age-, weight-, and height-adjusted relative risk (RR) factors for overall hip fracture and for trochanteric fracture and cervical fracture separately. RESULTS: Spinal trabecular BMD was modestly related to overall hip fracture (RR, 1.4-1.7; P < .05) and strongly associated with trochanteric fracture (RR, 4.2-4.5; P < .005). Spinal integral BMD related similarly to overall hip fracture (RR, 1.7-1.8; P < .05) but more weakly to trochanteric fracture (RR, 2.3-3.2; P < .01). No spinal BMD measures were significantly related to cervical fracture. BMD at the hip was strongly related to overall hip fracture (RR, 3.3-4.3; P < .001), cervical fracture (RR, 2.7-5.3; P < .001), and trochanteric fracture (RR, 2.9-7.2; P < .001). CONCLUSION: Spinal trabecular BMD is strongly associated with both trochanteric and vertebral fractures.

Absorptiometry, Photon↗
PubMed1997

Spinal trabecular bone loss and fracture in American and Japanese women.

This study examined trabecular bone mineral density (BMD) in Japanese women with and without spinal fracture, and compared the results to American women with and without fracture. The quantitative computed tomography (QCT) systems used at the University of California, San Francisco (UCSF) and at Nagasaki University were cross-calibrated. Normative BMD was assessed with the K2HPO4 liquid phantom in 538 Americans aged 20-85 years, and with the B-MAS200 phantom in 577 Japanese aged 20-83 years. These BMD were adjusted for use with the Image Analysis solid phantom using the result of cross-calibration. The trabecular BMD in 111 postmenopausal American women (55 with fracture), and in 185 postmenopausal Japanese women (67 with fracture) were compared for investigation of the difference in BMD values relative to fracture status. The absolute BMD values in Japanese were lower than those in Americans, and the differences were greater with advancing age. The magnitude of the BMD difference was 8.6, 20.5, 38.1 mg/cm3 in women aged 20-24 years, 40-44 years, 60-64 years, respectively. In premenopausal women, BMD began to decrease at the age of 20 in Japanese, whereas the peak bone mass was maintained until the age of 35 in the American women. In immediate postmenopausal women, BMD significantly decreased in both populations. In later postmenopausal women, BMD significantly decreased with age in the Japanese women but decreased less rapidly in the American women. The aging decrease of BMD was 1.4% and 2.2% per year in the later postmenopausal American and Japanese women, respectively. The fracture threshold is considered to be lower in Japanese women. However, the BMD difference between American and Japanese women with fracture was similar to that without fracture. The Z-scores of fracture subjects versus controls were 2.9 in American and 1.8 in Japanese women. In conclusion, Japanese women were found to have a lower BMD and lower fracture threshold than American women. The significant decrease of spinal trabecular BMD in late postmenopause is potentially responsible for the higher prevalence of spinal fracture in Japanese women.

Adult↗
PubMed1997

Volumetric quantitative computed tomography of the proximal femur: precision and relation to bone strength.

We have developed a three-dimensional computed tomography (CT) scanning and image analysis method for measurement of trabecular and integral bone mineral density (BMD) and geometry in automatically determined femoral-neck and trochanteric subregions of the proximal femur. We measured the correlation of the density and geometry variables to femoral strength assessed in vitro under loading simulating a single-limb condition and a fall to the side. While BMD alone accounted for 48%-77% of the variability in strength for the stance loading configuration, femoral neck cross-sectional area (minCSA) and femoral neck axis length (FNAL) also contributed independently to femoral strength, and a combination of BMD and geometry variables explained 87%-93% of the variance in the data. For the fall loading configuration, trochanteric trabecular BMD alone explained 87% of the variability of strength. The reproducibility in vivo of the technique was assessed in a group of seven postmenopausal women, who underwent repeat scans with repositioning. For trabecular BMD, the precision was 1.1% and 0.6% for the femoral neck and trochanteric subregions, respectively, compared to 3.3% and 1.6% for the corresponding integral envelopes. Thus, trabecular BMD measurements were reproducible and highly correlated to biomechanical strength measurements. These results support further exploration of quantitative CT for assessment of osteoporosis at the proximal femur.

Accidental Falls↗