Predictive value of bone mineral density and morphology determined by peripheral quantitative computed tomography for cancellous bone strength of the proximal femur

Peripheral quantitative computed tomography (pQCT) is an established diagnostic method for assessment of bone mineral density in the diagnosis of osteoporosis. However, the capacity of structural parameters of cancellous bone measured by high-resolution computed tomography remains to be explored. In 33 patients, bone mineral density (BMD) of the proximal femur was measured in vitro by pQCT using cylindrical biopsies from the intertrochanteric region harvested before the implantation of an artificial hip joint. By digital image analysis of CT scans, parameters derived from histomorphometry describing the microarchitecture of cancellous bone were measured. The biopsies were also loaded to failure by an uniaxial compression test to determine the biomechanical parameters, Young's modulus, strength, and maximum energy absorption (E(max)). Strong correlations were found for BMD vs. mechanical parameters (r = 0.73 for Young's modulus, r = 0.82 for strength, and r = 0.79 for E(max); p < 0.001, n = 29). The morphological parameters, bone volume per trabecular volume (BV/TV), apparent trabecular thickness (app.Tb.Th), apparent trabecular separation (app.Tb.Sp), and trabecular number (Tb.N), correlated significantly with all mechanical parameters. The combination of morphological parameters with BMD in a multivariate regression model led to an overall, but only moderate, increase in R(2) in all cases. Our data confirm the high predictive value of BMD for the mechanical competence of cancellous bone of the intertrochanteric region. However, quantification of cancellous bone structure by image analysis of CT scans may provide additional qualitative information for the analysis of bone strength.     

Nondestructive determination of iliac crest cancellous bone strength by pQCT

The close relationship between apparent bone density and compressive strength is well established. In clinical situations, histomorphometry, and determination of the compressive strength on bone biopsies are destructive methods and require two separate biopsies from each patient. The aim of this study was to evaluate whether volumetric bone density measured by peripheral quantitative computed tomography (pQCT) could be used as a nondestructive method for estimating trabecular bone strength of iliac crest bone biopsies, thereby allowing the same biopsy to be used for subsequent histomorphometry. Materials consisted of trabecular bone samples prepared from unilateral transiliac crest bone samples obtained at autopsy [total 95 specimens; 41 females (21–90 years) and 54 males (23–87 years)]. From these, the apparent density of the cancellous bone was evaluated by pQCT in a 1-mm-thick slice in the middle of the biopsy and also by ash density measurement. Bone strength was measured by compression test. A strong power relationship was found between density measured by pQCT and compressive strength (r = 0.93, p < 0.00001). Likewise, there was a strong power relationship between ash density and compressive strength (r = 0.97, p < 0.00001). A linear correlation was found between pQCT measurement and ash density (r = 0.98, p < 0.00001), indicating a very high accuracy for the pQCT measurement. In conclusion, pQCT provides a very good estimate of cancellous bone strength. This nondestructive assessment of strength of iliac crest bone biopsies thereby enables biomechanical information as well as histomorphometric measurements to be obtained from the same biopsy.     

Alfacalcidol treatment increases bone mass from anticatabolic and anabolic effects on cancellous and cortical bone in intact female rats

It has been reported that alfacalcidol had an anticatabolic and anabolic effect on bone in ovariectomized and aged male rat models, but this has not been tested on intact female rats. The current study was to determine the effects of alfacalcidol on cancellous and cortical bone in intact female rats with or without exercise. Seventy-four, 8.5-month-old, intact female rats were orally treated with 0, 0.005, 0.025, 0.05, or 0.1 microg/kg alfacalcidol alone or in combination with raised cage (RC) exercise for 3 months. In vivo peripheral quantitative computerized tomography (pQCT) of the proximal tibial metaphyses (PTM) and ex vivo histomorphometric analyses of the PTM and tibial shaft (TX) were performed. Only the 0.1 microg alfacalcidol/kg dose proved to be anabolic. pQCT analysis showed that this dose increased total and cortical bone mineral content and density and trabecular bone mineral density. Histomorphometrically, it induced an anabolic response by increased trabecular mass and microarchitecture from stimulated cancellous bone and bone bouton formations, and suppressed bone resorption more than bone formation on the trabecular and endocortical surfaces, to produce a positive bone balance. A positive correlation between trabecular connectivity and bone bouton numbers occurred. These findings suggest alfacalcidol treatment augments bone mass by increased cancellous bone mass and improved trabecular architecture through its anticatabolic and anabolic properties in the intact adult female rat. Last, raised cage exercise alone or the combination of raised cage and alfacalcidol was no more effective than alfacalcidol alone.     

Impact of Weight Loss With Intragastric Balloon on Bone Density and Microstructure in Obese Adults

The historical concept that obesity protects against bone fractures has been questioned. Weight loss appears to reduce bone mineral density (BMD); however, the results in young adults are inconsistent, and data on the effects of weight loss on bone microstructure are limited. This study aimed to evaluate the impact of weight loss using an intragastric balloon (IGB) on bone density and microstructure. Forty obese patients with metabolic syndrome (mean age 35.1?±?7.3 yr) used an IGB continuously for 6 mo. Laboratory tests, areal BMD, and body composition measurements via dual-energy X-ray absorptiometry, and volumetric BMD and bone microstructure measurements via high-resolution peripheral quantitative computed tomography were conducted before IGB placement and after IGB removal. The mean weight loss was 11.5%. After 6 mo, there were significant increases in vitamin D and carboxyterminal telopeptide of type 1 collagen levels. After IGB use, areal BMD increased in the spine but decreased in the total femur and the 33% radius. Cortical BMD increased in the distal radius but tended to decrease in the distal tibia. The observed trabecular bone loss in the distal tibia contributed to the decline in the total volumetric BMD at this site. There was a negative correlation between the changes in leptin levels and the measures of trabecular quality in the tibia on high-resolutionperipheral quantitative computed tomography. Weight loss may negatively impact bone microstructure in young patients, especially for weight-bearing bones, in which obesity has a more prominent effect.     

Peripheral computed tomography (pQCT) detected short-term effect of AAACa (heated oyster shell with heated algal ingredient HAI): A double-blind comparison with CaCO3 and placebo

Trabecular bone density at the distal radius and cortical bone density at the midradius were measured in four randomized groups of women before and after 4 months administration of AAACa, oyster shell heated under reduced pressure with addition of heated algal ingredient (HAI) (group A); AACa, the same preparation without HAI (group B); CaCO₃ (group C); and placebo (group D) in a double-blind system using peripheral quantitative computed tomography (pQCT) with lumbar spine density measurement by dual-energy X-ray absorptiometry (DXA). Groups A, B, and C received 900 mg/day elemental calcium and D received none. In subjects of group A, but not B, C, and D, radial trabecular bone density increased significantly, to 106.2% ± 2.1% of the initial value (mean ± SEM). The increase of trabecular bone density was significantly different from the placebo group (D) only in AAACa (group A) and not in AACa (group B) and the calcium carbonate (group C). Cortical bone density increase was also greater in group A (but not in B and C) than in D. Lumbar spine density did not change significantly. AAACa was apparently more effective, increasing trabecular bone density more than AACa and CaCO₃ containing the same amount of elemental calcium. Received: July 17, 1999 / Accepted: Dec. 27, 1999     

Three-dimensional texture analysis of cancellous bone cores evaluated at clinical CT resolutions

The objective of this study was to determine if three-dimensional (3D) Haralick co-occurrence texture measures calculated from low-resolution CT images of trabecular bone correlate with 3D structural indices measured from high-resolution CT images. Thirty-three cubical regions of trabecular bone from human calcanei were analyzed using images obtained from a micro-computed tomography (micro-CT) scanner. 3D measures of bone architecture were calculated. The original images were then subsampled by factors of 5, 10, 15, and 20, and 3D texture features were calculated for each set of subsampled images. Linear regression models showed that co-occurrence texture features were significantly correlated with structural indices. Over 90% of the variation in three different structural indices was explained in two-variable regression models using texture features as predictors when the voxel side length was reduced by a factor of 10. Texture features calculated from clinical images may increase our ability to obtain trabecular bone architectural information when high-resolution images are unobtainable.     

Bone mineral density in children with primary hyperoxaluria type I.

BACKGROUND: In primary hyperoxaluria type I (PH 1), hepatic overproduction of oxalate leads to its deposition in various organ systems including bone (oxalosis). To evaluate skeletal status non-invasively in PH 1 we measured bone mineral density (BMD). METHODS: Peripheral quantitative computed tomography of the distal radius was performed in 10 children with PH 1 (mean chronological age 9+/-3.1, mean skeletal age 8.3+/-3.0 years): seven were on conservative treatment (CT) including one patient after pre-emptive liver transplantation (PH1-CT) and three were studied with end-stage renal disease on peritoneal dialysis (PH1-ESRD). RESULTS: Mean trabecular bone density (TBD) was significantly increased in PH1-ESRD compared with both age-matched healthy and uraemic controls (65227 vs. 168+/-63 and 256+/-80 mg/cm(3); P<0.002 and P<0.007, respectively), while cortical bone density (CBD) was elevated to a lesser degree (517+/-23 vs. 348+/-81 vs. 385+/-113 mg/cm(3); P<0.02 and P<0.04, respectively). In PH 1, CBD and, even more so, TBD were significantly correlated with serum creatinine (r=0.91 and r=0.96, P<0.0001, respectively) and plasma oxalate levels (r=0.86 and r=0.94, P<0.001 and P<0.0001, respectively). In children with PH 1 and normal glomerular function, both CBD and TBD were comparable with healthy controls. CONCLUSION: These preliminary data suggest that in PH 1 BMD is significantly increased in ESRD, probably due to oxalate disposal. Measurement of BMD may be a valuable and non-invasive tool in determining and monitoring oxalate burden in this disorder.     

Effective therapy of glucocorticoid-induced osteoporosis with medroxyprogesterone acetate

Summary The effect of long-acting medroxyprogesterone acetate (MPA) on the trabecular bone density in patients with glucocorticoid-induced osteoporosis (GCO) was evaluated. Thirteen steroid-dependent asthmatic male patients with GCO were administered 200 mg MPA intramuscularly at 6-week intervals and 1 g of elemental calcium daily for a period of 1 year. Ten additional matched steroid-dependent asthmatic male patients received 1 g of elemental calcium daily (controls). All 23 patients involved in the study had vertebral trabecular bone densitometry (TBD) by quantitative computed tomography (QCT) at baseline and at 6 and 12 months into the study. A 17% increase in TBD was found in the MPA-treated patients at 1 year (from 68.5±5 to 80.2±4 mg K₂HPO₄/cc) in contrast to the control group who experienced a 21% decrease in TBD during the same period of time (from 80.5±7 to 63.7±8 mg K₂HPO₄/cc) (T=6.90,P=0.0001 df=21). There were no significant changes in other parameters followed during the study in the MPA-treated group (serum calcium, phosphorus, magnesium, PTH, alkaline phosphatase, triglycerides, total and HDL cholesterol, urinary excretion of calcium, phosphate, creatinine) except for a decrease in the serum luteinizing hormone (LH) and testosterone (P<0.01) as well as of the hydroxyproline-creatinine ratio (P<0.01). The results lend support to the hypothesis of a progesterone-glucocorticoid competitive antagonism at the bone level, though other possibilities can be entertained, and suggest MPA as an effective therapy for glucocorticoid-induced osteoporosis in men.     

Mechanical Properties of Ewe Vertebral Cancellous Bone Compared With Histomorphometry and High-Resolution Computed Tomography Parameters

The goal of the present study was to determine if a high-resolution computed tomography (HRCT) system with 150 μm resolution was sufficient to predict mechanical properties in ewe lumbar vertebrae. To answer this question, we used a triangular comparison between: HRCT; biomechanics (compression and shear tests); and histomorphometry, which was the reference method for the measurements of morphometric parameters. Two dissected lumbar vertebrae (L-4 and L-5) from 32 ewes were used. Both compressive and shear properties correlated significantly with amount of bone and structural parameters evaluated by histomorphometry (bone volume/tissue volume, trabecular thickness, trabecular separation), but no significant correlation was found with the trabecular number. With our shear test involving the trabecular architecture itself more significant correlations were found with the node-strut analysis parameters than from the compressive test. Significant correlations were also found between HRCT and histological parameters (bone volume/tissue volume, bone surface/bone volume, trabecular separation, trabecular number, total strut length, number of nodes, and number of termini). Correlations between HRCT structural parameters and mechanical properties on L-4 were of the same magnitude as the correlations between the histomorphometric structural parameters and mechanical results on L-5 but with the remarkable advantage that HRCT is a noninvasive method. In spite of the resolution (150 μm) of our HRCT system, which entailed mainly an enlargement of the thinnest trabeculae or their loss during the segmentation process, we obtained coherent relationships between mechanical and tomographic parameters. The thinnest trabeculae probably had little effect on the mechanical strength. Also, this type of resolution allows us to consider the possibility of perfecting an in vivo HRCT system. However, physical density and bone mineral density correlated much better with strength than either classical histomorphometric or tomographic parameters. The current conclusion is fairly negative with respect to the ability of HRCT to assess mechanical properties nondestructively as compared with dual-energy X-ray absorptiometry. But, the noninvasive nature of the imaging modality and the capacity for three-dimensional imaging at arbitrary orientation make HRCT a promising tool in the quantitative assessment of cancellous architecture.     

Patient-specific microarchitecture of vertebral cancellous bone: a peripheral quantitative computed tomographic and histological study

This study directly compares peripheral quantitative computed tomography (pQCT) and histology for the assessment of 11 morphological parameters. Sixty-eight cylindrical cancellous bone samples were cored from the thoracic (T-9) thoracolumbar (T-12 or L-1), and lumbar (L-4) vertebral bodies of nine autopsy subjects (aged 44–88 years). Four transverse slices were acquired by pQCT from the bottom to the top of each cylinder. Slice thickness was 300 μm and pixel size was 70 × 70 μm. Thin sections (5 μm) were obtained at the same location in the samples, stained with Von Kossa, and photographed. Classical morphological parameters and strut analysis parameters were measured on all images (272 pQCT and 272 matched histological sections). Because of the partial volume effect and specific thresholding procedure, pQCT overestimated the absolute value of the bone volume fraction (BV/TV) and trabecular thickness (Tb.Th) by a factor 2. The trabecular number (Tb.N), trabecular spacing (Tb.Sp), and total strut length (TSL) were correctly estimated. However, the direct correlation between pQCT and histology was excellent (r² > 0.85, p < 0.001) for BV/TV, Tb.N, Tb.Sp, TSL, and star surface. For Tb.Th, number of nodes, and number of free ends, the correlation was also good (r² > 0.6, p < 0.001). Using a random regression model, we also explored the ability of these parameters to add structural information to the readily available BV/TV or apparent density. The model identified significant (p < 0.001) differences between subjects. For a given BV/TV, some patients had more trabeculae (Tb.N) that were thinner (Tb.Th) and more disconnected (higher free ends and star). This was observed for both histology and pQCT morphometrical data. Our analysis demonstrates the capacity of both histology and pQCT to detect subjects with specific structural patterns in vertebral cancellous bone.     

Bone Density Measurements by Computed Tomography in Osteogenesis Imperfecta Type I

The objectives of this study were (1) to determine whether there are differences in bone density in children versus adults with osteogenesis imperfecta type I (OI-type I) using computed tomography (CT) bone density measurements, (2) to determine whether there are differences in bone density between normal infants and infants with OI-type I using CT bone density measurements and (3) to determine whether CT bone density measurements could be helpful in investigating the infant with unexplained fractures. CT bone density measurements determine both the cortical bone density (CBD) and the trabecular bone density (TBD). CT bone density was determined using the OsteoQuant in 14 individuals with OI-type I who ranged in ages from 8 months to 45 years. The control groups consisted of over 1000 normal individuals, mostly adults, and included 7 normal infants who ranged in age from 10 months to 27 months. One of the individuals with OI-type I was a 4-month-old infant with multiple, unexplained fractures who had no other features of OI-type I and whose parents were accused of child abuse. Infants and children with OI-type I had low CBD and low TBD compared with normal controls, whereas adults with OI-type I had low TBD and high CBD when compared with controls. The one infant with multiple unexplained fractures and no other features of OI-type I had a bone density profile suggesting OI-type I with a low TBD and low CBD. Subsequent collagen analysis showed biochemical evidence of OI-type I. Individuals with OI-type I have abnormal CT bone density profiles that evolve over time from a low CBD and low TBD during infancy and childhood to a high CBD and low TBD during adulthood. This may explain the decreased frequency of fractures in individuals with OI-type I in adulthood compared with childhood. Individuals with OI-type I can present with only multiple unexplained fractures and have no other clinical features to strongly suggest the diagnosis. CT bone density measurements can be helpful in these atypical cases of OI-type I and should be considered in the investigation of the infant with unexplained fractures to help distinguish intrinsic bone disease from child abuse. Received: 19 May 1998 / Accepted: 23 September 1998     

Changes in bone structure after augmentation cystoplasty in chronic uraemic rats

OBJECTIVE: To investigate the effect of urinary diversion using several types of intestinal segments on cortical and cancellous bone structure of growing rats with renal insufficiency. MATERIAL AND METHODS: In all, 110 female Sprague-Dawley rats (8 weeks old) had either a two-stage subtotal nephrectomy by removing five-sixths of the renal mass, or a sham operation. Except for a uraemic control group, all uraemic rats then had an enterocystoplasty using stomach, ileum or colon (20 animals per group). An additional group with colic augmentation received the bisphosphonate ibandronate. After 12 weeks, the left tibia was assessed using peripheral quantitative computed tomography and bone histomorphometry. RESULTS: After subtotal nephrectomy all groups had approximately 30% less endogenous creatinine clearance. Renal failure alone or in association with gastric or colic augmentation induced only negligible changes in the mass and structure of cortical and cancellous tibial bone. In contrast, rats after ileal augmentation and renal failure had a significant reduction in cancellous bone mineral density (P < 0.05) whereas the reduction in trabecular bone area and volume was not statistically significant. Furthermore, ileocystoplasty caused a decrease in trabecular number and perimeter, increased trabecular separation and enlarged bone marrow space, whereas ileocystoplasty had no effect on cortical bone. The changes were not associated with alterations in serum pH. Ibandronate treatment in the colonic cystoplasty group increased trabecular bone mass and structural variables over the untreated colonic cystoplasty group. CONCLUSIONS: These results suggest that cystoplasty using an ileal segment causes a decrease in bone mass and architecture in growing rats with mild uraemia. It remains open to question whether the results obtained from experimental animals can be directly extrapolated to the clinical situation.     

Precision of 3D Registration Analysis for Longitudinal Study of Second-Generation HR-pQCT

Objective: The objective of this research was to develop 3D registration analysis method in longitudinal studies of high-resolution peripheral quantitative computed tomography (HR-pQCT), to analyze ranges of bone microstructure parameters in addition to standard parameters, and to test the precision of these measurements. Methods: Scans of HR-pQCT and analysis of bone microstructure were performed at 3 times in 15 subjects. The 3 images were matched 3-dimensionally, and bone microstructures were analyzed in the common region. In addition to standard measurement parameters of geometry, bone mineral density (BMD), trabecular bone, and cortical bone, parameters showing plate to rod-like structure, connectivity, cavity formation of trabecular bone, and bending stability of cortical bone were also measured. Precision was evaluated with the root mean square percent coefficient variance (RMS%CV). Results: RMS%CV was 0.1%–1.3% for geometry, 0.6%–1.9% for BMD, 0.8%–3.3% for trabecular bone, 2.1%–9.8% for additionally measured trabecular bone, 1.0%–3.4% for cortical bone excluding Ct.Po, 6.0%–6.1% for Ct.Po, and 0.8%–1.5% for additionally measured cortical bone. Precision was higher for 3D registration than for 2D registration in geometry, BV/TV, and Ct.Po. Conclusions: 3D registration analysis of a range of bone microstructural parameters in longitudinal analysis of HR-pQCT showed good precision, offering potential for contributing to future research on osteoporosis and bone metabolic diseases.     

High‐resolution peripheral quantitative computed tomography can assess microstructural and mechanical properties of human distal tibial bone

High‐resolution peripheral quantitative computed tomography (HR‐pQCT) is a newly developed in vivo clinical imaging modality. It can assess the 3D microstructure of cortical and trabecular bone at the distal radius and tibia and is suitable as an input for microstructural finite element (µFE) analysis to evaluate bone's mechanical competence. In order for microstructural and image‐based µFE analyses to become standard clinical tools, validation with a current gold standard, namely, high‐resolution micro‐computed tomography (µCT), is required. Microstructural measurements of 19 human cadaveric distal tibiae were performed for the registered HR‐pQCT and µCT images, respectively. Next, whole bone stiffness, trabecular bone stiffness, and elastic moduli of cubic subvolumes of trabecular bone in both HR‐pQCT and µCT images were determined by µFE analysis. The standard HR‐pQCT patient protocol measurements, derived bone volume fraction (BV/TV^d), trabecular number (Tb.N*), trabecular thickness (Tb.Th), trabecular spacing (Tb.Sp), and cortical thickness (Ct.Th), as well as the voxel‐based direct measurements, BV/TV, Tb.N*, Tb.Th*, Tb.Sp*, Ct.Th, bone surface‐to‐volume ratio (BS/BV), structure model index (SMI), and connectivity density (Conn.D), correlated well with their respective gold standards, and both contributed to µFE‐predicted mechanical properties in either single or multiple linear regressions. The mechanical measurements, although overestimated by HR‐pQCT, correlated highly with their gold standards. Moreover, elastic moduli of cubic subvolumes of trabecular bone predicted whole bone or trabecular bone stiffness in distal tibia. We conclude that microstructural measurements and mechanical parameters of distal tibia can be efficiently derived from HR‐pQCT images and provide additional information regarding bone fragility. © 2010 American Society for Bone and Mineral Research     

Bone microarchitecture is more severely affected in patients on hemodialysis than in those receiving peritoneal dialysis

We used high-resolution quantitative computed tomography to study the microarchitecture of bone in patients with chronic kidney disease on dialysis. We compared bone characteristics in 56 maintenance hemodialysis (21 women, 14 post-menopausal) and 23 peritoneal dialysis patients (9 women, 6 post-menopausal) to 79 healthy men and women from two cohorts matched for age, body mass index, gender, and menopausal status. All underwent dual-energy X-ray absorptiometry of the spine and hip to measure areal bone mineral density, and high-resolution peripheral quantitative computed tomography of the radius and tibia to measure volumetric bone mineral density and microarchitecture. When compared to their matched healthy controls, patients receiving hemodialysis and peritoneal dialysis had a significantly lower areal bone mineral density in the hip. Hemodialysis patients had significantly lower total, cortical, and trabecular volumetric bone mineral density at both sites. Hemodialysis patients had significantly lower trabecular volumetric bone mineral density and microarchitecture at the tibia than the peritoneal dialysis patients. Overall, peritoneal dialysis patients were less affected, their cortical thickness at the distal tibia being the only significant difference versus controls. Thus, we found more severe trabecular damage at the weight-bearing tibia in hemodialysis compared to peritoneal dialysis patients, but this latter finding needs confirmation in larger cohorts.     

Cut-off Values Determined for Vertebral Fracture by Peripheral Quantitative Computed Tomography in Japanese Women

In spite of the benefits of bone mass measurement by dual-energy X-ray absorptiometry (DXA), the use of DXA has limitations. It is unable to assess a true bone density, and cannot discriminate between the trabecular and cortical bone compartments. Ultradistal radius bone density was measured using peripheral quantitative computed tomography (pQCT) to determine reference values for total bone density (BD), trabecular bone density (TBD), polar strength strain index (pSSI), total bone mineral content (BC), trabecular bone mineral content (TBC), cortical bone density (CBD), cortical bone mineral content (CBC) and polar cross-sectional moment of inertia (pCSMI) in the Japanese female population, and to ascertain the cut-off values of the measured indicators that could most efficiently discriminate osteoporotic subjects with vertebral fractures. A total of 5266 healthy Japanese women aged 20–89 years were included in this study to determine Japanese reference values. Additionally, 621 who had undergone radiographic examination of the thoracic and lumbar spine at the time of pQCT measurement were selected to determine the cut-off values of BD, TBD, pSSI and other indicators for vertebral fractures. All the healthy subjects were divided into 5 year age groups. The BD showed nonsignificant changes from the 20–24 year age group to the 45–49 year age group, and fell significantly thereafter. The TBD maintained a plateau until the 40–44 year group, which corresponds to the young adult mean (YAM) values of the lumbar spine, femoral neck and radius BMDs measured using DXA. The TBD decreased significantly thereafter. The pSSI did not change significantly from the 20–24 year age group to the 45–49 year age group, and decreased slightly in the 50–54 year age group and markedly after 55–59 years. The cut-off values for the discrimination of vertebral fractures were obtained by the calculation of sensitivities, specificities and the area under the curves obtained using age-adjusted receiver operating characteristics (ROC) analysis. Odds ratios and 95% confidence limits (CL) were calculated using age-adjusted logistic analysis. The cut-off values for vertebral fractures, the area under the ROC curves (AUC) and odds ratios were 270.1 mg/cm³ (−2.2 SD, 66.6% of YAM), 0.689 ± 0.025, 2.10 (1.63, 2.70) for BD, 104.8 mg/cm³ (−2.2 SD, 53.5% of YAM), 0.699 ± 0.023, 2.17 (1.69, 2.77) for TBD and 192.8 mm³ (−1.9 SD, 59.8% of YAM), 0.631 ± 0.028, 1.72 (1.34, 2.21) for pSSI, respectively. These findings suggest that ultradistal radius BMD measured using pQCT can be used to discriminate women with vertebral fractures. Received: 3 August 2000 / Accepted: 5 March 2001     

Can the fast bone loss in osteoporotic and osteopenic patients be stopped with active vitamin D metabolites?

The aim of this study was to evaluate whether fast trabecular bone loss in osteoporotic and osteopenic patients can effectively be treated with active vitamin D metabolites. Thirty-one osteoporotic and osteopenic patients were monitored between 4 and 22 months before and between 8 and 18 months during the treatment. Fast bone losers were designated as osteoporotic or osteopenic patients with a loss of trabecular bone density in the radius of 3% or more calculated for 1 year. For this differentiation, the high precise peripheral quantitative computed tomography system (DENSISCAN 1000) was used (reproducability 0.3% in mixed collectives). The pretreatment loss and the ``gain' under treatment with active vitamin D metabolites was calculated for 1 year. The treatment consisted of either 0.5 μg calcitriol daily or 1 μg of alfacalcidol daily. Before treatment, the trabecular bone loss in the radius/year was −6.6 ± 0.5% (mean ± SEM). After treatment with vitamin D metabolites, the trabecular bone gain in the radius/year was 0.01 ± 0.6% (mean ± SEM). The difference was highly significant (P < 0.001). In contrast to this, the loss of cortical bone density before treatment was −1.8 ± 0.3% (mean ± SEM) and the reduced loss after treatment −0.2 ± 0.4% (mean ± SEM), both values calculated for 1 year. This difference was less significant (P < 0.05). This study shows that the treatment with active vitamin D metabolites is very effective in slowing fast trabecular bone loss in osteoporotic and osteopenic patients.     

A study of trabecular bones in ovariectomized goats with micro-computed tomography and peripheral quantitative computed tomography

Osteoporotic fractures occur most frequently in trabeculae-rich skeletal sites. The purpose of this study was to use a high-resolution micro-computed tomography (micro-CT) to investigate the changes in trabecular bone microarchitecture and to use a peripheral quantitative computed tomography (pQCT) to study changes in volumetric bone mineral density (BMD) in a large animal model resulted from ovariectomy (OVX). Ten adult goats were used for this study. The first iliac crest biopsy was harvested before OVX and served as baseline; the second biopsy was collected 6 months later from the opposite side for both pQCT and micro-CT measurements. Results showed that after 6 months of OVX, the BMD of the iliac crest biopsies decreased significantly by 16.3% (P < 0.05). The bone volume density (BV/TV), trabecular number (Tb.N), and connectivity density (Conn.D) measured with micro-CT decrease significantly after OVX, with an average decrease of 8.34%, 8.51%, and 18.52% (P < 0.05 each), respectively. The trabecular plate separation (Tb.Sp) was 8.26% (P < 0.05) greater than baseline after OVX. Significant correlations were found between the reduction of BMD and the decreases of BV/TV and Tb.N (r = 0.839 and 0.719, respectively; P< 0.001 both), as well as the increase of Tb.Sp (r = -0.758, P< 0.001) and SMI (r = -0.697, P< 0.001). In conclusion, this was the first experimental study in goat model to show that OVX-induced bone loss in goats was attributed by deterioration of trabecular microarchitecture.     

Ultrasound velocity and broadband attenuation over a wide range of bone mineral density

Ultrasound velocity (UV) and broadband ultrasound attenuation (BUA) were studied in human and bovine bone with a wide range of bone mineral density (BMD). The BMD of 98 fresh specimens was measured by quantitative computed tomography: 42 cancellous specimens from women in the age group of 64±4 years; 51 bovine cancellous and 5 bovine cortical. BMD values ranged from 90 to 400 mg/cm³ for the human cancellous bone, 310 to 870 mg/cm³ for the bovine cancellous bone, and 1750 to 1780 mg/cm³ for the bovine cortical bone. BMD showed a strong linear correlation with apparent density over the entire range of density (r=0.979). UV of human and bovine cancellous bone was 1480 –2650 m/s and 2880–3100 m/s for bovine cortical bone. BUA values were 1–61 dB/MHz/cm for the cancellous specimens and 5–12 dB/MHz/cm for cortical specimens. UV was found to be linear with BMD for all specimens; however, BUA was linear with BMD only for the specimens from elderly women. A quadratic relationship between BUA and BMD was found when the bovine samples were included.