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At least 19 recordsLinked to original sources
PubMed2004

Bone mass evaluated by calcaneous ultrasound and radial peripheral computed tomography in 726 youngsters.

AIM: To compare the results of ultrasound and computed peripheral tomography in evaluating bone mass in a population of normal children. METHODS: Seven hundred and twenty-six healthy school children (260 males; age 8.3-20.9 y) underwent calcaneous ultrasound and peripheral computed tomography at the ultradistal radius. Broadband ultrasound attenuation (BUA) and areal and volumetric bone mineral density (aBMD and vBMD) were evaluated. The results were compared and correlated among them and with auxological parameters (height, BMI and pubertal stages) using the software package SPSS for Windows. RESULTS: The three variables examined (BUA, aBMD and vBMD) all showed a progressive increase with age and a positive correlation with age, height and BMI. When the population was subdivided according to pubertal stages, all variables showed a progressive increase, the difference being significant when stages 1-2 were compared with stages 4-5. A significant correlation was present among BUA, aBMD and vBMD even if the Pearson correlation coefficient was not high. CONCLUSIONS: The similar pattern of BUA, aBMD and vBMD with respect to age, height and pubertal stages indicates that ultrasound could be a reliable method to screen bone mass abnormalities in children. The low correlation coefficient, however, suggests that the methods employed measure different bone parameters. Moreover, the different skeletal locations could also account for these results.

Adolescent↗
PubMed1999

Measurement of forearm bone in children by peripheral computed tomography.

By means of peripheral computed tomography (pQCT), adult cortical bone density and volume was shown to be under a fixed rectilinear relationship regardless of age, sex, and presence or absence of osteoporosis. In children, however, the density-volume regression line followed a clearly different slope from that for adults (P < 0. 001), indicating a difference in property and composition of the cortical bone between growing bone of children and grown-up bone of adults. Although both relative cortical volume and density increased with age in both boys and girls, no significant increase of trabecular bone was noted in either during the growth period. When the same technique was applied to the bone of rats known to continue growing with indefinite modeling without remodeling, the regression line between cortical bone density and volume was different from that of adult humans and similar to that of growing human children. Growing bone in a constant process of modeling and mineralization thus seems to have cortical bone possibly with less complete mineralization somewhat different from those of grown-up bone only undergoing remodeling. Selective cortical bone measurement by pQCT appears to be useful in characterizing the unique properties of the cortex of the growing bone.

Adolescent↗
PubMed1997

Quantitative assessment of experimental fracture repair by peripheral computed tomography.

An experimental fracture model was used to assess bone mineral density at the fracture site by peripheral computed tomography and to compare the model with biomechanical, histological, and radiographic methods for the quantification of the fracture repair process. Transverse osteotomies in the mid-diaphysis of 28 tibia of sheep were externally fixed and mineral densities, cross-sectional areas, flexural rigidities, tissue composition, and projected callus area were calculated after 9 weeks of healing time. BMD measured by pQCT was strongly correlated with histologically determined percentages of mineralized tissue in the osteotomy gap (R = 0.71) and in the periosteal callus (R2 = 0.62). The percentage of mineralized tissue in the osteotomy gap was the best predictor of the flexural rigidity of the tibiae (R2 = 0.74). Because of high correlations with the histological findings, the volumetric BMD at the level of the osteotomy gap was also strongly correlated with the biomechanical findings (R2 = 0.70). Neither the cross-sectional area in pQCT nor the projected callus area in plane film radiography were positively correlated to the flexural rigidity of the tibiae. Quantitative computed tomography proved to be a successful estimator for the prediction of the mechanical stability of healing bones. The noninvasive procedure is a reliable tool for the quantification of the fracture repair process in experimental studies and may be useful for treatment decisions in particular clinical situations.

Animals↗
PubMed1994

Quantitative peripheral computed tomodensitometric study of cortical and trabecular bone mass in relation with menopause.

Changes in total, cortical and trabecular bone mass were studied using quantitative peripheral computed tomodensitometry on the forearm of 58 normal eugonadal premenopausal women and 116 normal postmenopausal women to evaluate the evolution of bone components with age. In premenopausal women, no changes were seen in any bone component. In postmenopausal women, only trabecular bone mass diminished in the first 5 years after menopause (P < 0.05). It continued to decrease in the next 5 years (P < 0.05), but not later. Cortical bone mass experienced a significant loss 6-10 years after menopause (P < 0.001), and more than 15 years after menopause (P < 0.0005). These results are similar to those obtained with other techniques, and document the differing behavior of the cortical and trabecular bone components with years of menopause.

Adolescent↗
PubMed1997

Factors associated with cortical and trabecular bone loss as quantified by peripheral computed tomography (pQCT) at the ultradistal radius in aging women.

Peripheral quantitative computed tomography (pQCT) allows the separate determination of cortical and trabecular bone mineral density in the peripheral skeleton. This cross-sectional study was designed to examine the effects of healthy aging on pQCT measurements at the ultradistal radius. In a well-defined sample of 129 community-based women, aged 70-87 years, the differences in cortical and trabecular density over the age range were equivalent to losses of -0.41% and -0.65% per year, respectively. To investigate the mechanism of this age-related decline, we assessed relationships between both parameters and height, weight, body mass index, dietary calcium intake, grip strength, and serum concentrations of insulin-like growth factor-I (IGF-I), calcidiol (25(OH)D3), calcitriol (1,25(OH)2D3), parathyroid hormone (PTH), and sex hormone binding globulin (SHBG). Multiple regression was used to adjust for potential confounders. Age was not significant after controlling for other covariables. Body mass index, grip strength, serum IGF-I, 25(OH)D3, and PTH (1-84) were found to be independent predictors of total bone density. Including (total or free) 1,25(OH)2D3 did not improve the model precision. These findings provide evidence that, among other factors, the activity of the growth hormone-IGF-I-axis is of importance for skeletal integrity. Grip strength, serum IGF-I, and PTH (1-84) were discovered to be significantly related to cortical but not to trabecular density, suggesting that different mechanisms may be involved in compact and cancellous bone loss.

Aged↗
PubMed1996

Cortical and total bone mineral content of the radius: accuracy of peripheral computed tomography.

The aim of the study was to evaluate the accuracy of an XCT 960 Stratec peripheral quantitative computed tomography (pQCT) device in assessing bone mineral content of the radius. We scanned 27 left forearm specimens excised from cadavers and focused on cortical bone mineral content (BMCc) at the junction of the middle and distal third and on total bone mineral content (BMCtot) at the distal end of the radius. Cylindrical specimens matched with those two sites were cut using a diamond circular saw, embedded in a polyester resin and subsequently submitted to two reference methods, nondestructive neutron activation analysis and flame atomic absorption spectrometry. Mineral contents measured by pQCT were closely correlated with those assessed by using the two reference methods, with correlation coefficients ranging from 0.862 to 0.960. The standard error of the estimate amounted 7-10% for the BMCc (junction of the middle and distal third), and 17-18% for the BMCtot (distal end). We conclude that pQCT is able to measure either cortical or total mineral content of the radius with a high degree of accuracy.

Aged↗
PubMed1994

Precision of dual X-ray absorptiometry and peripheral computed tomography using mobile densitometry units.

Irrespective of the method used for noninvasive bone mass determination, data comparison between different centers is a major problem as significant interunit variation may occur. We, therefore, have employed mobile densitometry units to reduce interunit variability in two large epidemiologic studies in Germany. Two cars were equipped with either two dual X-ray absorptiometry (DXA) instruments (QDR 1000 Hologic, USA) (car I) or a special purposed scanner for peripheral quantitative computed tomography (pQCT) (XCT 900, Stratec, FRG) (car II). The cars were moved across Germany 11,090 km and 1651 km during the studies over a period of 30 and 7 months, respectively. Precision in vitro was determined using hydroxyapatite phantoms. Forty-eight patients underwent duplicate measurements at the lumbar spine (n = 22) and hip (n = 26) for assessing reproducibility in vivo. Between the two series of scans, the car was moved 63 km. Long-term precision in vitro of the QDR 1000 instruments were 0.41% and 0.59% for BMD with no evidence of machine drift (rate of change per year 0.04% and 0.05%, respectively). Short-term reproducibility in vivo showed a coefficient of variation (cv) of 1.02% for spinal BMD (L2-L4) and 1.72% for femoral neck. Long-term precision in vitro of the pQCT scanner was 0.9%. Our study shows precision in vivo and in vitro and stability of the mobile densitometers similar to that achieved with stationary equipment. In conclusion, mobile densitometry may become a useful tool not only for epidemiologic surveys and clinical trials but also for routine evaluation in less densely populated areas.

Absorptiometry, Photon↗
PubMed2000

[Osteoporosis and phytoestrogens: an assessment of bone mineral density via quantitative peripheral computed tomography in milk-egg-vegetarian women in the premenopause].

PURPOSE: Noninvasive assessment of bone mineral density, geometrical and biomechanical properties in premenopausal women with dietary intake of phytoestrogens and comparison of these parameters with those of age-matched female subjects with "Mediterranean" dietary intake lacking in these substances. MATERIAL AND METHODS: Volumetric cortical, trabecular and total mineral density and bone geometrical properties were evaluated in 15 female subjects with phytoestrogens dietary intake. Peripheral quantitative Computed Tomography (pQCT) was used to make measurements at the distal radius of the nondominant forearm. Fifteen age-matched subjects with "Mediterranean" dietary intake were chosen as a control group. Cross-sectional area (Total A), trabecular area (TA), cortical area (CA), cortical thickness (CThk) and strength strain index (SSI) were assessed as biomechanical parameters. RESULTS: Daily consumption of phytoestrogens was significatively different in the two groups (phy: 17.45 mg/die vs ctr: 0.35; p < 0.0005), while calcium intake was similar (phy: 652 mg/die vs ctr: 650). Total (0.460 g/cm3 vs ctr: 0.433) and trabecular (phy: 0.209 g/cm3 vs ctr: 0.189) bone mineral densities, such as SSI (phy: 925 mm3 vs ctr: 894) values, were higher in women with dietary intake of phytoestrogens, in comparison with the relative controls, but not significantly (p = ns). Among geometrical parameters, total area and cortical area were tendential in women with a vegetarian diet while cortical thickness was the same in both groups. CONCLUSIONS: pQCT showed higher bone mineral density (total and trabecular) and SSI values in premenopausal women with dietary intake of phytoestrogens. Despite the lack of statistical significance, these preliminary results, should further support the few literature findings about the potential role of phytoestrogens consumption in preventing trabecular bone loss. However, further studies are warranted to evaluate definitively the efficacy of phytoestrogens in preventing postmenopausal osteoporosis.

Adult↗
PubMed2000

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.

Absorptiometry, Photon↗
PubMed1981

What pathologists should know and be able to do in laboratory data processing and computers: peripheral devices and storages.

This article is the second in a five-part educational series on laboratory data processing and computers. The authors describe the major components of peripheral storage and the limitations of input/output devices, and analyze in terms of laboratory workflow the type and placement of input/output devices. Preceding the article are competency areas and performance objectives, defined by the Laboratory Computer Applications and Data Processing Committee. Following the article are questions with which readers can test their understanding of the material. Next month the authors will focus on software.

Computers↗
PubMed1981

Description and applications of a programmable stimulation system for electrophysiology, used as a computer peripheral.

An original programmable stimulation and data acquisition system of general interest for electrophysiology is presented. It can be used as a peripheral of any 12 (or more) bits mini- or microcomputer. With the software described it is possible to determine stimulation parameters automatically as a function of results obtained during the experiment or from the keyboard. Verification of parameters is carried out by permanent registration on the terminal screen, in numerical and analog form, and by facultative printout from the teleprinter. Two applications in electrophysiology are presented: the measurement of thresholds and the establishment of response curves.

Analog-Digital Conversion↗
PubMed2004

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.

Animals↗
PubMed2005

Recommendations for thresholds for cortical bone geometry and density measurement by peripheral quantitative computed tomography.

Peripheral quantitative computed tomography (pQCT) is widely used for clinical and research purposes. For accurate determination of bone geometry (bone cross-sectional area, cortical thickness, and cortical area), volumetric bone mineral density (vBMD) and cortical bone mineral content (BMC), it is important to select the appropriate thresholds. A Stratec XCT-2000 scanner was used to compare current standard practice with new optimized thresholds. Currently, a single threshold of 710 mg/mL for the measurement of cortical vBMD and geometry is used. We hypothesised that this threshold may not be optimal and used the European Forearm Phantom (EFP) and patient data to test more appropriate thresholds. A single slice (1.2 mm width, 0.4 mm pixel size) was made at section 4 of the EFP (representing the diaphyseal portion of a long bone). The EFP has a known cortical thickness of 2.5 mm and, therefore, the correct threshold for geometry would be that which measures cortical thickness as 2.5 mm. Thresholds were altered at approximately the 50% value between soft tissue (60 mg/mL) and peak density (879 mg/mL), and cortical thickness versus threshold was plotted; the correct threshold for geometry was 460 mg/mL. By expressing this threshold as a percentage of the range of density values in the EFP ([460-60]/[879-60] = 49%) and then applying this percentage to in vivo data, the optimum threshold for geometry can be determined: ([1240-79] x 0.49) + 79 = 648 mg/mL. For cortical vBMD of in vivo bone measurements at the midshaft site of the radius, thresholds were varied around the peak value (1240 mg/mL), and the threshold was set to that which gave a cortical density of 1240 mg/mL; the threshold for cortical density was, therefore, 1200 mg/mL. A subset of radius scans from a population of young healthy females was analyzed using the new thresholds (648 mg/mL for bone geometry, 1200 mg/mL for cortical vBMD) versus the current threshold (710 mg/mL). For bone geometry, the mean difference between the analysis based on the new threshold and that based on the manufacturer-recommended threshold ranged between 2.1% and 14% (total area = 2.1%, cortical thickness = 14%, cortical area = 3.7%). Although there was a 10% difference between the analysis based on the new threshold and that based on the manufacturer-recommended threshold, this difference was not systematic. Thresholds will significantly affect results obtained from pQCT. The current threshold of 710 mg/mL is inadequate for accurate determination of bone geometry and cortical vBMD. New thresholds of 648 mg/mL for geometry and 1,200 mg/mL for cortical vBMD should be used.

Absorptiometry, Photon↗
PubMed2001

Bone densities and bone size at the distal radius in healthy children and adolescents: a study using peripheral quantitative computed tomography.

Peripheral quantitative computed tomography (pQCT) has the ability to improve the diagnostic utility of densitometry in children and adolescents, because bone size and volumetric bone mineral density (vBMD) can be measured independently. Nevertheless, detailed reference data are lacking. We therefore performed pQCT (XCT-2000 scanner, Stratec, Inc., Pforzheim, Germany) at the distal radius in 371 healthy children, adolescents, and young adults (185 males and 186 females, ages 6-23 years) and in 107 of their parents (19 men and 88 women, ages 29-40 years). Total vBMD, trabecular, and "cortical + subcortical" vBMD as well as cross-sectional area (CSA) were determined at the "4% site" of the distal radius. This location was defined as the site whose distance to the most distal portion of the growth plate or to the radial articular surface corresponded to 4% of the forearm length. In both genders, total vBMD remained stable between 6 and 15 years of age and then increased by 30% in girls and by 46% in boys. Regarding pubertal development, total vBMD remained almost constant throughout pubertal stages 1-4 and thereafter increased in both genders. Trabecular vBMD did not change with age in girls, whereas in boys an increase with age of about 10% was noted after 15 years of age. Males had higher trabecular vBMD than females. This gender difference increased from 6% in prepubertal children to 23% in adults. The variation with age and pubertal stage in "cortical + subcortical" vBMD-cort was similar to that of total vBMD. CSA roughly doubled between 6 and 15 years of age in both genders. In conclusion, the availability of this reference material will provide a basis for the use of pQCT in the assessment of pediatric bone diseases.

Absorptiometry, Photon↗