| 1. |
- Arvidsson, Bo, 1962-, et al.
(författare)
-
Reference data for bone mineral density in Swedish women using digital X-ray radiometry
- 2013
-
Ingår i: Journal of clinical densitometry. - New York, USA : Elsevier. - 1094-6950 .- 1559-0747. ; 16:2, s. 183-188
-
Tidskriftsartikel (refereegranskat)abstract
- During the last decade, digital X-ray radiometry (DXR) has been used to measure bone mineral density (BMD) in the metacarpal bones. The aim of this study was to establish Swedish reference material for bone mass in women, measured in the metacarpal bones with DXR, and compare these data with the data from the manufacturer. A sample of 1440 women aged 20-79yr living in Örebro County was randomly assigned from the population register. Microdose mammography was used (Sectra MDM L30; Sectra Imtec AB, Linköping, Sweden) to measure BMD. Cole's LMS method was used to calculate DXR. Six hundred sixty-nine (48.3%) women participated. Peak bone mass occurred at the age of 43.4yr with a BMD of 0.597g/cm(2) (standard deviation: 0.050). Our Swedish data correlated well with the manufacturer's material. Only among women aged 50-59yr did BMD differ, where the Swedish sample had lower values. The LMS method can be used to describe the DXR data and provide a more detailed picture of bone density distribution. DXR-BMD in Swedish women aged 20-79yr is equivalent to findings from other studies, showing the same distribution of BMD in most age groups except for ages 50-59yr.
|
|
| 2. |
- Kälvesten, Johan, et al.
(författare)
-
Potential sources of quantification error when retrospectively assessing metacarpal bone loss from historical radiographs by using digital X-ray radiogrammetry : an experimental study
- 2014
-
Ingår i: Journal of clinical densitometry. - : Elsevier. - 1094-6950 .- 1559-0747. ; 17:1, s. 104-108
-
Tidskriftsartikel (refereegranskat)abstract
- During the past 15 yr, digital X-ray radiogrammetry (DXR) has been used to measure metacarpal bone mineral density (BMD). BMD is often measured in existing cohorts where X-ray images were not acquired in accordance with the DXR imaging protocol (DIP). The purpose of the present study was to analyze how deviations from DIP in historical radiographs may affect the reproducibility of DXR-BMD measurements. Cadaver hand phantoms were used to conduct repeat measurements of deviations from DIP with respect to voltage, exposure, lateral displacement, supination, combination of lateral displacement and supination or rotation, extension of the wrist, and edge enhancement. Direct digital radiography (Aristos; Siemens Healthcare, Erlangen, Germany) was used for image acquisition and dxr-online (Sectra, Linkoping, Sweden) for DXR-BMD measurements. The influence of the tested deviations from DIP ranged from 0 to 32.5 mg/cm(2) (0-6.8%). On repetition with the same specimen, none of the deviations resulted in a within-specimen reproducibility error greater than 2 mg/cm(2) (0.4%, equivalent to a T-score of 0.042). Among the tested deviations, all except tube voltage had a magnitude greater than the normal measurement noise for the technique and must therefore be considered when planning a study based on historical images.
|
|
| 3. |
|
|
| 4. |
- Callréus, Mattias, et al.
(författare)
-
Country-Specific Young Adult Dual-Energy X-Ray Absorptiometry Reference Data Are Warranted for T-Score Calculations in Women: Data From the Peak-25 Cohort.
- 2014
-
Ingår i: Journal of Clinical Densitometry. - : Elsevier BV. - 1094-6950. ; 17:1, s. 129-135
-
Tidskriftsartikel (refereegranskat)abstract
- The aims of this study were to provide normative data for dual-energy X-ray absorptiometry (DXA) in 25-yr-old women and evaluate whether young adult Swedish women have bone mineral density (BMD) comparable with DXA manufacturer reference values and other equivalent populations. BMD at all sites was measured in the population-based Peak-25 cohort (n = 1061 women; age, 25.5 ± 0.2yr). BMD values were standardized (sBMD) and compared against the Third National Health and Nutrition Examination Survey (NHANES III) and other cohorts. Based on the DXA manufacturer-supplied reference values, Z-scores were 0.54 ± 0.98 (femoral neck [FN]), 0.47 ± 0.96 (total hip [TH]), and 0.32 ± 1.03 (lumbar spine [LS]). In comparison with other studies, sBMD was higher in the Peak-25 cohort (FN, 1.5%-8.3%; TH, 3.9%-9.2%; and LS, 2.4%-6.5%) with the exception of trochanter-sBMD which was 2.5% lower compared with NHANES III. The concordance in identifying those in the lowest or highest quartile of BMD was highest between hip measurements (low, 71%-78% and high, 70%-84%), corresponding discordance of 0%-1%. At this age, the correlation between DXA sites was strong (r = 0.62-0.94). BMD in Swedish young adult women is generally higher than has been reported in other equivalently aged European and North American cohorts and suggests that the high fracture incidence in Sweden is not explained by lower peak bone mass. The use of nonregional-specific DXA reference data could contribute to misdiagnosed osteoporosis in elderly women.
|
|
| 5. |
- Lenora, Janaka, et al.
(författare)
-
Effect of Precision on Longitudinal Follow-Up of Bone Mineral Density Measurements in Elderly Women and Men.
- 2010
-
Ingår i: Journal of Clinical Densitometry. - : Elsevier BV. - 1094-6950. ; 13:4, s. 407-412
-
Tidskriftsartikel (refereegranskat)abstract
- Precision error of dual-energy X-ray absorptiometry exceeds the expected annual rate of bone loss in the elderly. The capacity to detect changes in areal bone mineral density (aBMD; g/cm(2)) over a 5-yr period was assessed. Six hundred ninety-one women, 75.2 (0.1)yr, from the Malmö OPRA-study, were measured using Lunar DPX-L (GE Lunar, Madison, WI), and 211 men, 74.7 (3.2)yr, from the Malmö Mr Os-study, were measured using Lunar Prodigy (GE Lunar) with follow-up 5yr later. Precision error was determined with 30 degrees of freedom. Least significant change (LSC, i.e., 2.77xprecision error) was calculated. Women's precision errors (g/cm(2)) for DPX-L were 0.028 (total hip [TH]) and 0.016 (lumbar spine [LS]), and for Prodigy, they were 0.009 (TH) and 0.039 (LS). In men, corresponding results for Prodigy were 0.014 and 0.031. In women, 41% and in men, 39% had aBMD changes exceeding the LSC at TH. Follow-up intervals (i.e., LSC/median rate of aBMD change) for both women and men were 8yr (TH) and 13yr (LS). Based on Prodigy precision data, follow-up intervals for women were 3 and 32yr at TH and LS. In summary, several years were needed to detect change. Only when a high rate of bone loss is suspected, a short follow-up time is possible, in elderly persons.
|
|
| 6. |
- Leslie, William D, et al.
(författare)
-
Selection of women aged 50-64 yr for bone density measurement.
- 2013
-
Ingår i: Journal of Clinical Densitometry. - : Elsevier BV. - 1094-6950. ; 16:4, s. 570-8
-
Tidskriftsartikel (refereegranskat)abstract
- The fracture risk assessment tool from the World Health Organization (FRAX(®)) estimates 10-yr major osteoporotic and hip fracture probabilities from multiple clinical risk factors and optionally femoral neck bone mineral density (BMD). FRAX without BMD has been proposed as a method to select postmenopausal women younger than 65yr for BMD measurement, but the efficiency of this strategy and its concordance with National Osteoporosis Foundation (NOF) treatment guidelines is unknown. The osteoporosis self-assessment test (OST) is another simple screening tool based on age and weight alone. A historical cohort of 18,315 women aged 50-64yr, drawn from the Manitoba Bone Density Program database, which contains clinical BMD results for the Province of Manitoba, Canada, was used to determine the performance of these screening tools in selecting postmenopausal women younger than 65yr for BMD testing. FRAX was closely aligned with indicators of high fracture risk (area under the receiver operating characteristic curve [AUROC]: 0.89), whereas OST was better for detecting women with osteoporotic BMD (AUROC: 0.72). The combination of major fracture probability 10% or higher from FRAX without BMD or OST less than 1 identified 42% of women for BMD testing, capturing 72% of women meeting any NOF treatment criteria (90% of women with NOF criteria for high risk from FRAX or prior fracture). The negative predictive value to exclude qualification for treatment under the NOF criteria was 90%. These data may help to inform an evidence-based approach for targeting BMD testing in postmenopausal women younger than 65yr under the NOF treatment guidelines.
|
|
| 7. |
- Rianon, Nahid J., et al.
(författare)
-
Fracture Risk Assessment in Older Adults Using a Combination of Selected Quantitative Computed Tomography Bone Measures: A Subanalysis of the Age, Gene/Environment Susceptibility-Reykjavik Study
- 2014
-
Ingår i: Journal of Clinical Densitometry. - : Elsevier BV. - 1094-6950. ; 17:1, s. 25-31
-
Tidskriftsartikel (refereegranskat)abstract
- Bone mineral density (BMD) and geometric bone measures are individually associated with prevalent osteoporotic fractures. Whether an aggregate of these measures would better associate with fractures has not been examined. We examined relationships between self-reported fractures and selected bone measures acquired by quantitative computerized tomography (QCT), a composite bone score, and QCT-acquired dual-energy X-ray absorptiometry-like total femur BMD in 2110 men and 2682 women in the Age, Gene/Environment Susceptibility-Reykjavik Study. The combined bone score was generated by summing gender-specific Z-scores for 4 QCT measures: vertebral trabecular BMD, femur neck cortical thickness, femur neck trabecular BMD, and femur neck minimal cross-sectional area. Except for the latter measure, lower scores for QCT measures, singly and combined, showed positive (p < 0.05) associations with fractures. Results remained the same in stratified models for participants not taking bone-promoting medication. In women on bone-promoting medication, greater femur neck cortical thickness and trabecular BMD were significantly associated with fracture status. However, the association between fracture and combined bone score was not stronger than the associations between fracture and individual measures or total femur BMD. Thus, the selected measures did not all similarly associate with fracture status and did not appear to have an additive effect on fracture status.
|
|
| 8. |
- Aslanzadeh, Solmaz, et al.
(författare)
-
Biogas Production from N-Methylmorpholine-N-oxide (NMMO) Pretreated Forest Residues
- 2014
-
Ingår i: Applied Biochemistry and Biotechnology. - : Humana Press, Inc.. - 0273-2289 .- 1559-0291. ; 172:6, s. 2998-3008
-
Tidskriftsartikel (refereegranskat)abstract
- Lignocellulosic biomass represents a great potential for biogas production. However, a suitable pretreatment is needed to improve their digestibility. This study investigates the effects of an organic solvent, N-Methylmorpholine-N-oxide (NMMO) at temperatures of 120 and 90 °C, NMMO concentrations of 75 and 85 % and treatment times of 3 and 15 h on the methane yield. The long-term effects of the treatment were determined by a semicontinuous experiment. The best results were obtained using 75 % NMMO at 120 °C for 15 h, resulting in 141 % increase in the methane production. These conditions led to a decrease by 9 % and an increase by 8 % in the lignin and in the carbohydrate content, respectively. During the continuous digestion experiments, a specific biogas production rate of 92 NmL/gVS/day was achieved while the corresponding rate from the untreated sample was 53 NmL/gVS/day. The operation conditions were set at 4.4 gVS/L/day organic loading rate (OLR) and hydraulic retention time (HRT) of 20 days in both cases. NMMO pretreatment has substantially improved the digestibility of forest residues. The present study shows the possibilities of this pretreatment method; however, an economic and technical assessment of its industrial use needs to be performed in the future.
|
|
