Dual X-ray Absorptiometry Examinations Research Articles

Application of magnetic resonance image compilation (MAGiC) in the diagnosis of middle-aged and elderly women with osteoporosis

ObjectiveTo investigate the feasibility of diagnosing osteoporosis (OP) in women through magnetic resonance image compilation (MAGiC).MethodsA total of 110 patients who underwent lumbar magnetic resonance imaging and dual X-ray absorptiometry examinations were collected and divided into two groups according bone mineral density: osteoporotic group (OP) and non-osteoporotic group (non-OP). The variation trends of T1 (longitudinal relaxation time), T2 (transverse relaxation time) and BMD (bone mineral density) with the increase of age, and the correlation of T1 and T2 with BMD were examined by establishing a clinical mathematical model.ResultsWith the increase of age, BMD and T1 value decreased gradually, while T2 value increased. T1 and T2 had statistical significance in diagnosing OP (P < 0.001), and there is moderate positive correlation between T1 and BMD values (R = 0.636, P < 0.001), while moderate negative correlation between T2 and BMD values (R=-0.694, P < 0.001). Receiver characteristic curve test showed that T1 and T2 had high accuracy in diagnosing OP (T1 AUC = 0.982, T2 AUC = 0.978), and the critical values of T1 and T2 for evaluating osteoporosis were 0.625s and 0.095s, respectively. Besides, the combined utilization of T1 and T2 had higher diagnostic efficiency (AUC = 0.985). Combined T1 and T2 had higher diagnostic efficiency (AUC = 0.985). Function fitting results of OP group: BMD=-0.0037* age − 0.0015*T1 + 0.0037*T2 + 0.86, sum of squared error (SSE) = 0.0392, and non-OP group: BMD = 0.0024* age − 0.0071*T1 + 0.0007*T2 + 1.41, SSE = 0.1007.ConclusionT1 and T2 value of MAGiC have high efficiency in diagnosing OP by establishing a function fitting formula of BMD with T1, T2 and age.

Uticaj lokalnih vibracija na mineralnu gustinu kostiju distalne podlaktice

A prolonged, mainly professional, exposure to hand-arm vibration (HAV) may cause a complex chronic disorder of the upper extremities known as Hand-Arm Vibration Syndrome (HAVS). Besides vascular and neurological injuries, such exposure to HAV may cause various bone disorders in the form of cystic changes, exostoses, aseptic necrosis, osteoarthritis, spontaneous fractures and osteoporosis. The objective of this study was to examine whether there were any changes in the bone mineral density in the distal forearm in persons professionally exposed to HAV. In a group of 31 workers professionally exposed to vibrations (29 men and 1 woman) with neurological and/or vascular signs of HAVS, the bone mineral density of the distal part of the radius of both hands was examined by dual X-ray absorptiometry (DXA). The control group consisted of 25 healthy subjects with no history of HAV exposure. Osteopenia was found in 14 subjects (45.16%), which makes a statistically significant difference compared to the control group (p=0.017), where osteopenia was found in 3 subjects (12.0%). Osteoporosis was not found in any of the subjects. Analyzing the value of T score for the dominant (-0.81±0.58 SD) and non-dominant hand (-0.62±0.68SD) in our patients, we found no statistically significant difference in the average T score values of the dominant and non-dominant hand (p=0.269). Changes in bone density at the distal radius are common in persons occupationally exposed to HAV. Distal forearm DXA examination in workers occupationally exposed to HAV can help diagnose HAVS.

Does Quantitative Ultrasound at the Calcaneus Predict an Osteoporosis Diagnosis in Postmenopausal Women from the Silesia Osteo Active Study?

The aims of the study were to assess the clinical conformity between quantitative ultrasound (QUS) and densitometry with use of the standard World Health Organization T-score thresholds to determine optimal diagnostic cutoff values for QUS T-scores in different age groups. Three hundred sixty-five postmenopausal Caucasian women were enrolled into the study and divided into two age groups (<65 y and ≥65 y). Skeletal status was assessed using QUS measurements at the calcaneus and bone densitometry at the spine and proximal femur (Hologic Explorer, Bedford, MA, USA). QUS measurement results expressed as the stiffness index (SI) correlated significantly with both femoral neck bone mineral density (r = 0.51, p < 0.0001) and lumbar spine bone mineral density (r = 0.52, p < 0.0001). On the basis of receiver operating characteristic curve analyses, the thresholds for correspondence between QUS T-score values and T-score –2.5SD in dual X-ray absorptiometry (DXA) were established. They ranged between –1.63SD and –1.70SD in relation to femoral neck DXA and between –1.22SD and –1.51SD in relation to lumbar spine DXA, depending on age category. In conclusion, the study described here confirmed that QUS measurements at the calcaneus may provide information comparable to DXA examinations at the femoral neck and lumbar spine in postmenopausal women.

Duodenal histopathology and laboratory deficiencies related to bone metabolism in coeliac disease.

Coeliac disease (CD) is a chronic immune-mediated small intestine enteropathy precipitated by gluten in genetically predisposed individuals. Adult presentation is often atypical and malabsorption of vitamins and minerals is common, with a consequent disturbance of bone metabolism. We aim to evaluate laboratory deficiencies related to bone metabolism and the relationship between severity of histological damage and degree of bone mass loss at diagnosis of CD. A retrospective cross-sectional study of 176 adult coeliac patients was carried out. All patients fulfilled the histopathological criteria for CD. Biochemical data were analysed (calcium/phosphate/alkaline-phosphatase/vitamin D/parathormone). Duodenal histology was classified according to the Marsh classification. Bone mass density (BMD) at the lumbar and femoral regions measured by dual X-ray absorptiometry. A P-value of less than 0.05 was considered significant. No correlation was found between the presence of gastrointestinal symptoms and the Marsh histopathological stage (P>0.05). Vitamin D deficiency was most common (44.5%), whereas only 5.7% had hypocalcaemia. Calcium was lower (P<0.05) and parathormone was higher (P=0.01) in patients with Marsh III. These patients had lower lumbar T-score (P<0.05). Although low BMD occurred in all age groups, most osteoporotic patients were aged 45-49 years (81.8%). A multiple regression analysis showed that the Marsh histopathological stage could be a predictor of lower lumbar BMD (r=0.322, B=-1.146, P<0.05). Laboratory deficiencies and decreased BMD could be severe and unrelated to the presence of gastrointestinal symptoms. At diagnosis, the Marsh histopathological stage could predict the occurrence of low BMD, which carries a risk of developing into osteoporosis. In coeliac patients older than 30 years, evaluation of bone biomarkers and dual X-ray absorptiometry examination should be considered.

Low bone mineral density and fat-free mass in younger patients with a femoral neck fracture.

Reduced bone mineral density (BMD) together with muscle wasting and dysfunction, that is sarcopenia, emerges as a risk factor for hip fracture. The aim of this study was to examine body composition and BMD and their relationship with trauma mechanisms in young and middle-aged patients with femoral neck fracture. Altogether, 185 patients with femoral neck fracture aged 20-69 were included. BMD, body composition and fat-free mass index (FFMI) were determined by dual-X-ray absorptiometry (DXA), and trauma mechanisms were registered. Ninety per cent of the whole study population had a femoral neck BMD below the mean for age. In the young patients (< 50 years), 27% had a Z-score of BMD ≤ -2 SD. More than half of the middle-aged patients (50-69 years) had osteopenia, that is T-score -1 to -2.5, and 35% had osteoporosis, that is T-score < -2.5, at the femoral neck. Patients with low-energy trauma, sport injury or high-energy trauma had a median standardised BMD of 0.702, 0.740 vs. 0.803 g/cm(2) (P = 0.03), and a median FFMI of 15.9, 17.7 vs. 17.5 kg/m(2) (P < 0.001), respectively. FFMI < 10th percentile of an age- and gender-matched reference population was observed in one-third. A majority had low BMD at the femoral neck, and one-third had reduced FFMI (i.e. sarcopenia). Patients with fracture following low-energy trauma had significantly lower femoral neck BMD and FFMI than patients with other trauma mechanisms. DXA examination of both BMD and body composition could be of value especially in those with low-energy trauma.

Dual-Energy CT–based Phantomless in Vivo Three-dimensional Bone Mineral Density Assessment of the Lumbar Spine

To evaluate the feasibility of phantomless in vivo dual-energy computed tomography (CT)-based three-dimensional (3D) bone mineral density (BMD) assessment in comparison with dual x-ray absorptiometry (DXA). This retrospective study was approved by the institutional review board, and the requirement to obtain informed consent was waived. Data from clinically indicated dual-energy CT and DXA examinations within 2 months, comprising the lumbar spine of 40 patients, were included. By using automated dedicated postprocessing dual-energy CT software, the trabecular bone of lumbar vertebrae L1-L4 were analyzed and segmented. A mixed-effects model was used to assess the correlations between BMD values derived from dual-energy CT and DXA. One hundred sixty lumbar vertebrae were analyzed in 40 patients (mean age, 57.1 years; range, 24-85 years), 21 male (mean age, 54.3 years; range, 24-85 years) and 19 female (mean age, 58.5 years; range, 31-80 years). Mean BMD of L1-L4 determined with DXA was 0.995 g/cm(2), and 18 patients (45%) showed an osteoporotic BMD (T score less than -2.5) of at least two vertebrae. Mean dual-energy CT-based BMD of L1-L4 was 0.254 g/cm(3). Bland-Altman analysis with mixed effects demonstrated a lack of correlation between dual-energy CT-based and DXA-based BMD values, with a mean difference of 0.7441 and 95% limits of agreement of 0.7441 ± 0.4080. Dedicated postprocessing of dual-energy CT data allows for phantomless in vivo BMD assessment of the trabecular bone of lumbar vertebrae and enables freely rotatable color-coded 3D visualization of intravertebral BMD distribution.

AB0624 High correlation between a new ultrasonic method for spinal densitometry and dual x-ray absorptiometry

BackgroundOsteoporosis is a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue leading to increased fragility and augmented fracture risk. Bone densitometry performed through dual...

TBS (Trabecular Bone Score) and Diabetes-Related Fracture Risk

Type 2 diabetes is associated with increased fracture risk but paradoxically greater bone mineral density (BMD). Trabecular bone score (TBS) is derived from the texture of the spine dual x-ray absorptiometry (DXA) image and is related to bone microarchitecture and fracture risk, providing information independent of BMD. This study evaluated the ability of lumbar spine TBS to account for increased fracture risk in diabetes. We performed a retrospective cohort study using BMD results from a large clinical registry for the province of Manitoba, Canada. We included 29,407 women 50 years old and older with baseline DXA examinations, among whom 2356 had diagnosed diabetes. Lumbar spine TBS was derived for each spine DXA examination blinded to clinical parameters and outcomes. Health service records were assessed for incident nontraumatic major osteoporotic fractures (mean follow-up 4.7 years). Diabetes was associated with higher BMD at all sites but lower lumbar spine TBS in unadjusted and adjusted models (all P < .001). The adjusted odds ratio (aOR) for a measurement in the lowest vs the highest tertile was less than 1 for BMD (all P < .001) but was increased for lumbar spine TBS [aOR 2.61, 95% confidence interval (CI) 2.30-2.97]. Major osteoporotic fractures were identified in 175 women (7.4%) with and 1493 (5.5%) without diabetes (P < .001). Lumbar spine TBS was a BMD-independent predictor of fracture and predicted fractures in those with diabetes (adjusted hazard ratio 1.27, 95% CI 1.10-1.46) and without diabetes (hazard ratio 1.31, 95% CI 1.24-1.38). The effect of diabetes on fracture was reduced when lumbar spine TBS was added to a prediction model but was paradoxically increased from adding BMD measurements. Lumbar spine TBS predicts osteoporotic fractures in those with diabetes, and captures a larger portion of the diabetes-associated fracture risk than BMD.

Effects of anti-resorptive agents on trabecular bone score (TBS) in older women

We evaluated the longitudinal effects of anti-resorptive agents (534 treated women vs. 1,150 untreated) on lumbar spine bone mineral density (BMD) and trabecular bone score (TBS). TBS was responsive to treatment in women over age 50. The treatment-related increase in TBS was less than the increase in BMD, which is consistent with bone texture preservation. In addition to inducing an increase in BMD, anti-resorptive agents also help to preserve bone architecture. TBS, a new gray-level texture measurement, correlates with 3D parameters of bone micro-architecture independent of BMD. Our objective was to evaluate the longitudinal effects of anti-resorptive agents on lumbar spine BMD and TBS. Women (≥ 50 years), from the BMD program database for the province of Manitoba, Canada, who had not received any anti-resorptive drug prior to their initial dual X-ray absorptiometry (DXA) exam were divided into two groups: untreated, those without any anti-resorptive drug over the course of follow-up, and treated, those with a non-estrogen anti-resorptive drug (86 % bisphosphonates, 10 % raloxifene, and 4 % calcitonin). Lumbar spine TBS was calculated for each lumbar spine DXA examination. Changes in TBS and BMD between baseline and follow-up (mean follow-up 3.7 years), expressed in percentage per year, were compared between the two groups. A total of 1,150 untreated women and 534 treated women met the inclusion criteria. Only a weak correlation was seen between BMD and TBS in either group. Significant intergroup differences in BMD change and TBS change were observed over the course of follow-up (p < 0.001). Similar mean decreases in BMD and TBS (-0.36 %/year and -0.31 %/year, respectively) were seen for untreated subjects (both p < 0.001). Conversely, treated subjects exhibited a significant mean increase in BMD (+1.86 %/year, p < 0.002) and TBS (+0.20 %/year, p < 0.001). TBS is responsive to treatment with non-estrogen anti-resorptive drug therapy in women over age 50. The treatment-related increase in TBS is less than the increase in BMD, which is consistent with bone texture preservation.

Evaluation of vertebral bone marrow fat content by chemical-shift MRI in osteoporosis

To quantitatively evaluate vertebral bone marrow fat content and investigate its association with osteoporosis with chemical-shift magnetic resonance imaging (CS-MRI). Fifty-six female patients (age range 50-65 years) with varying bone mineral densities as documented with dual x-ray absorptiometry (DXA) were prospectively included in the study. According to the DXA results, the patients were grouped as normal bone density, osteopenic, or osteoporotic. In order to calculate fat content, the lumbar region was visualized in the sagittal plane by CS-MRI sequence. "Region of interest" (ROI)s were placed within L3 vertebral bodies and air (our reference point) at different time points by different radiologists. Fat content was calculated through "signal intensity (SI) suppression rate" and "SI Index". The quantitative values were compared statistically with those obtained from DXA examinations. Kruskal-Wallis, and Mann-Whitney U tests were used for comparisons between groups. The reliability of the measurements performed by two radiologists was evaluated with the "intraclass correlation coefficient". This study was approved by an institutional review board and all participants provided informed consent to participate in the study. Eighteen subjects with normal bone density (mean T score, 0.39 ± 1.3 [standard deviation]), 20 subjects with osteopenia (mean T score, -1.79 ± 0.38), and 18 subjects with osteoporosis (mean T score, -3 ± 0.5) were determined according to DXA results. The median age was 55.9 (age range 50-64 years) in the normal group, 55.5 (age range 50-64 years) in the osteopenic group, and 55.1 (age range 50-65 years) in the osteoporotic group (p = 0.872). In the CS-MRI examination, the values of "SI suppression ratio" and "SI Index" (median [min:max]) were calculated by the first and second reader, independently. There was no statistically significant difference between the groups with regard to vertebral bone marrow fat content (p > 0.05). According to the "intraclass correlation coefficient", the measurements were reliable (0.55 and 0.60). Vertebral bone marrow fat content calculated with CS-MRI is not a reliable parameter for predicting bone mineral density in female patients aged between 50 and 65 years.

Body fluid volumes measurements by impedance: A review of bioimpedance spectroscopy (BIS) and bioimpedance analysis (BIA) methods

This paper reviews various bioimpedance methods permitting to measure non-invasively, extracellular, intracellular and total body water (TBW) and compares BIA methods based on empirical equations of the wrist-ankle resistance or impedance at 50 kHz, height and weight with BIS methods which rely on an electrical model of tissues and resistances measured at zero and infinite frequencies. In order to compare these methods, impedance measurements were made with a multifrequency Xitron 4200 impedancemeter on 57 healthy subjects which had undergone simultaneously a Dual X-ray absorptiometry examination (DXA), in order to estimate their TBW from their fat-free-mass. Extracellular (ECW) and TBW volumes were calculated for these subjects using the original BIS method and modifications of Matthie [Matthie JR. Second generation mixture theory equation for estimating intracellular water using bioimpedance spectroscopy. J Appl Physiol 2005;99:780–1], Jaffrin et al. [Jaffrin MY, Fenech M, Moreno MV, Kieffer R. Total body water measurement by a modification of the bioimpédance spectroscopy method. Med Bio Eng Comput 2006;44:873–82], Moissl et al. [Moissl UM, Wabel P, Chamney PW, Bosaeus I, Levin NW, et al. Body fluid volume determination via body composition spectroscopy in health and disease. Physiol Meas 2006;27:921–33] and their TBW resistivities were compared and discussed. ECW volumes were calculated by BIA methods of Sergi et al. [Sergi G, Bussolotto M, Perini P, Calliari I, et al. Accuracy of bioelectrical bioimpedance analysis for the assessment of extracellular space in healthy subjects and in fluid retention states. Ann Nutr Metab 1994;38(3):158–65] and Hannan et al. [Hannan WJ, Cowen SJ, Fearon KC, Plester CE, Falconer JS, Richardson RA. Evaluation of multi-frequency bio-impedance analysis for the assessment of extracellular and total body water in surgical patients. Clin Sci 1994;86:479–85] and TBW volumes by BIA methods of Kushner and Schoeller [Kushner RF, Schoeller DA. Estimation of total body water by bioelectrical impedance analysis. Am J Clin Nutr 1986;44(3):417–24], Lukaski et al. [Lukaski HC, Bolonchuk WW. Estimation of body fluid volumes using tetrapolar bioelectrical impedance measurements. Aviat Space Environ Med 1988;59:1163–9], Hannan et al. [Hannan WJ, Cowen SJ, Fearon KC, Plester CE, Falconer JS, Richardson RA. Evaluation of multi-frequency bio-impedance analysis for the assessment of extracellular and total body water in surgical patients. Clinical Science 1994;86:479–85], Deurenberg et al. [Deurenberg P, van der Koy K, Leenen R, Westrate JA, Seidell JC. Sex and age specific prediction formulas for estimating body composition from bioelectric impedance: a cross validation study. Int J Obesity 1991;15:17–25] These volumes were compared against those given by BIS method and, in the case of TBW, with those by DXA. For ECW, a good agreement was found between various BIS methods and that of Sergi while Hannan's values were higher. Both Matthie's and Moissl's methods gave mean TBW resistivities and volumes lower than those of Jaffrin's and DXA methods. Kushner et al. method gave values of TBW not significantly different from those of Jaffrin et al. and DXA, as Hannan's method in men, but Lukaski and Deurenberg methods led to an underestimation.

Potential value of vertebral proton MR spectroscopy in determining osteoporosis

目的 探讨椎体氢质子MR波谱(1H MRS)测量值与双能X线(DXA)及定量CT(QCT)所测骨密度(BMD)值的相关性.方法 152名[30～80岁,平均(58±14)岁]女性志愿者分别进行以下检查:胸腰椎侧位(T4～L4)X线平片,并采用Genant半定量法对其进行评阅.腰椎(L2～4)用DXA及QCT进行BMD测量.腰椎常规行矢状面T2WI、T1 WI和横轴面T2WI.MR常规扫描结束后采用单体素点解析波谱(PRESS)序列对L2～4椎体进行波谱采集,相应谱线采用SAGE 7.0软件分析,并计算脂水比(LWR)、脂肪比(FF%)及水峰、脂峰线宽(LW)等相关椎体MRS定量指标.结果 FF%、LWR随年龄增加逐步增大;平均LWR(2.71)与DXA、QCT所测平均BMD值(分别为1.038g/cm2和104.2 mg/cm3)具有相关性(r值分别为-0.477、-0.769,P值均＜0.01).水峰LW随年龄增加呈逐渐变窄趋势,其同DXA、QCT测量的BMD具有相关性(r值分别为0.439、0.712,P值均＜0.01).脂峰线宽无明显变化趋势,且同DXA、QCT所测BMD无明显相关性(r值分别为-0.183、-0.199,P值均＞0.05).结论 MRS可在常规腰椎MR基础上无创性评估椎体骨髓状况,进而来评估骨髓的变化对于骨量所带来的影响。

Comparison of effective dose to children and adults from dual X-ray absorptiometry examinations

Dual X-ray absorptiometry (DXA) is increasingly used to measure bone density in children. If the system software does not include pediatric scan modes, then child examinations must be performed using adult scan modes that give a higher radiation dose to children than adults. This report describes a study to compare the effective dose to children and adults from DXA scans performed on the Hologic Discovery and QDR4500 models. Depth dose measurements were made using thermoluminescent dosimeters in a Rando phantom and were mapped onto the Cristy mathematical phantoms representing a 5-, 10- and 15-year-old child and an adult, and effective dose (ED) was calculated using the ICRP Publication-60 tissue weighting factors. The ED for spine (hip) examinations performed with the Express mode using the default adult scan lengths were 16.1 (9.8), 11.1 (6.7), 5.6 (3.9) and 4.4 (3.1) μSv for a 5-, 10- and 15-year-old child and adult respectively. However, if care is taken to adjust scan lengths appropriately, the child doses were reduced to 9.1 (7.4), 7.1 (5.9) and 5.0 (3.7) μSv. ED figures for the Fast and Array modes were larger by factors of 1.5 and 3 respectively. EDs for whole body scans for a 5-, 10- and 15-year-old child and adult performed on the A-model (W-model) were 5.2 (10.5), 4.8 (9.6), 4.2 (8.4) and 4.2 (8.4) μSv. Using the infant whole body mode (only available on the A-model), they were 7.5 μSv for a 1-year-old and 8.9 μSv for a neonate. Although doses from child DXA examinations are low, it is still important to keep them as small as possible. DXA operators using Discovery systems can do this by using the Express scan mode, by setting appropriate values of the scan length before scan acquisition and by avoiding mistakes that lead to scans having to be unnecessarily repeated.

Differing lumbar vertebral mineralization rates in ambulatory pediatric patients with osteogenesis imperfecta.

The purpose of this study was to evaluate serial changes in bone mineral density (BMD) of the lumbar spine in individual children and adolescents with untreated osteogenesis imperfecta (OI) using dual X-ray absorptiometry (DXA). Twenty-seven pediatric patients with OI who had no historical or radiographic evidence of lumbar fracture, required no assistive device for mobility, and were taking no medications known to affect skeletal mineralization during the study period comprised the investigational group. Absolute BMD and age- and gender-matched BMD (Z-scores) were assessed relative to standard parameters of growth (height, weight, age, height adjusted for age and gender and body surface area) and severity of disease (lifetime fracture rate). The spinal mineralization rate (SMR) between examinations for 15 patients with more than one measurement (n = 20 intervals) was expressed as the magnitude of the change in BMD Z-score per year. Both BMD and BMD Z-score were closely correlated with height, height Z-score, weight and body surface area and were inversely related to fracture rate (P < 0.001 for all comparisons). BMD was also highly correlated with patient age (P < 0.001). Stepwise regression analysis showed that together height Z-score and lifetime fracture rate improved the prediction of BMD Z-score (r = 0. 71; P < 0.001). SMRs ranged from -0.5 to 3.5. The average change in SMR between sequential measurements was 168% for the five children who had more than two DXA examinations. Linear regression showed a significant negative correlation between SMR and height Z-score (r = -0.79, P < 0.001). We conclude that vertebral body size is a critical determinant of BMD and BMD Z-score in OI because DXA results are expressed per unit area, not per unit volume. Pediatric patients with OI mineralize their lumbar vertebrae at rates similar to healthy children but tend to lag behind in overall mineralization. The rate of mineralization at any age appears to be related to the patient's height (adjusted for age- and gender-matched controls) and inversely related to the patient's lifetime rate of fractures. Our data suggest that vertebral mineralization in children with OI is related primarily to rapid increases in vertebral volume and only secondarily to increases in vertebral mineral density.