Dual-photon bone mineral density in the proximal femur: correlation by site

Using 153Gd dualphoton absorptiometry, bone mineral density (BMD) was measured in three areas of the proximal femur-the femoral neck, Ward's triangle and the greater trochanter-in 129 females referred for possible osteoporosis. In addition, lumbar spine bone density was determined. Lumbar spine BMD was significantly greater than any regional proximal femoral BMD (p less than 0.0001). Ward's triangle was significantly less than the trochanteric region (p less than 0.01) and both Ward's triangle and the greater trochanter were significantly less than the femoral neck (p less than 0.0005). Correlations within the three regions of the proximal femur are considerably higher than those between the spine and the proximal femur regions. This suggests that measurement of all three areas of the proximal femur is not essential for a satisfactory assessment of proximal femoral mineral content. In particular, since Ward's triangle is strongly correlated with the greater trochanter and the femoral neck, it may rationally be excluded from analysis of proximal femoral bone density.     

CT evaluation of trabecular and cortical bone mineral density of the lumbar spine in patients on hemodialysis

It is difficult to evaluate the severity of bone involvement in patients on maintenance hemodialysis (HD) by the measurement of vertebral bone mineral density (BMD), since many endocrine factors influence bone metabolism, making the value of BMD variable from high to low. It is also difficult to interpret the BMD measured in one ROI (region of interest) since bone density distribution is sometimes very heterogenous. On the other hand QCT method is useful to evaluate the value of trabecular and cortical bone mineral density separately. Vertebral BMD was measured in 138 patients on maintenance HD, by using DEQCT (dual energy QCT). 161 patients without bone metabolic disorders were studied for control group. In patients on HD, various BMD values ranging from high to low were observed, and there was no correlation between BMD value and duration of HD. The number of patients with low mineral content was greater than that with high mineral content in both cortical and trabecular bone. The trabecular BMD decreased with age, and the speed of BMD decline was the same in both sexes. The rapid decrease of trabecular BMD after menopause seen in control female group was not observed in female patients on hemodialysis. The deviation of BMD from the age-matched average BMD value was smaller in older male patients than that in young male and female patients. In order to evaluate the difference of change between the trabecular and cortical bone at the same vertebra, cases in which discrepancy of Z-score was more than 0.2 were divided into three groups; group A: increased trabecular BMD (Z-score greater than 1), group B: decreased trabecular BMD (-1 greater than Z-score), group C: normal trabecular BMD (-1 less than Z-score less than 1), and in each group T/C ratio (Z-score of trabecular BMD/Z-score of cortical BMD ratio) was evaluated. In group A, almost all cases showed trabecular BMD to be higher than cortical, and in group B, 60% cases showed trabecular BMD to be lower than cortical, suggesting that the change of BMD in trabecular bone is greater than that in cortical bone.     

健康老年妇女近段股骨骨密度和结构的定量CT研究

目的 采用定量CT(QCT)和双能X线吸收测量(DXA)仪对健康老年妇女近段股骨骨密度(BMD)和骨结构进行研究,并对2种测量方法的结果进行比较.方法 对66名65岁以上健康妇女左侧髋关节进行DXA测量,计算出股骨颈和粗隆区BMD;对其双侧近段股骨进行QCT测量,计算出股骨颈、粗隆区和整体股骨ROI的皮质骨、松质骨和总体骨的BMD和体积;并将QCT三维图像模拟DXA的平面投影计算出模拟DXA股骨颈BMD和模拟DXA股骨粗隆区BMD.对所获数据进行配对t检验或非参数秩和检验,并用Pearson法分析DXA和QCT相对应ROI的相关性.结果 用QCT可以对股骨近段不同ROI(股骨颈、粗隆区和整体股骨区)及不同骨成分(皮质骨、松质骨和总体骨)的BMD及体积等参数进行精确的定量分析.除右侧股骨颈皮质骨BMD[(0.52±0.04)g/cm3]、股骨粗隆区皮质骨BMD[(0.49±0.03)g/cm3]、股骨粗隆区综合骨BMD[(0.22±0.04)g/cm3]大于左侧相应参数[分别为[(0.51±0.04)、(0.48±0.03)、(0.21±0.04)g/cm3],差异均有统计学意义(P值均<0.05),但差别均<3.3%;而模拟DXA股骨颈BMD、模拟DXA股骨粗隆区BMD、股骨颈皮质骨体积、股骨颈松质骨BMD、股骨颈松质骨体积、股骨颈综合骨BMD、股骨颈综合骨体积、股骨粗隆区皮质骨体积、股骨粗隆区松质骨BMD、股骨粗隆区松质骨体积、股骨粗隆区综合骨体积左侧参数分别为(0.52±0.10)g/cm2、(0.78±0.13)g/cm2、5.80 cm3、(0.06±0.03)g/cm3、(5.19±1.40)cm3、(0.25±0.04)g/cm3、15.66 cm3、(21.74±3.43)cm3、(0.08±0.03)g/cm3、(34.27±6.09)cm3、(76.12±11.11)cm3,右侧分别为(0.52±0.10)g/cm2、(0.78±0.13)g/cm2、6.01 cm3、(0.06±0.02)g/cm3、(5.17±1.27)cm3、(0.25±0.04)g/cm3、15.62 cm3、(22.12±3.60)cm3、(0.09±0.03)g/cm3、(34.17±5.94)cm3、(76.53±10.71)cm3,差异均无统计学意义(P值均>0.05).左右两侧近段股骨QCT各相对应参数之间的r值范围在0.656～0.955,均具有相关性(P<0.05).QCT模拟DXA股骨颈和粗隆区BMD与真正DXA测量的相应值之间r值分别为0.685和0.855,具有相关性(P<0.05).结论 利用QCT技术可以对老年妇女近段股骨不同区域和不同成分的BMD和结构进行精确定量分析,QCT是骨质疏松研究中非常有用的测量技术.     

Study of optimal X-ray exposure conditions in consideration of bone mineral density: relation between bone mineral density and image contrast

Bone mineral density (BMD) increases through infancy and adolescence, reaching a maximum at 20-30 years of age. Thereafter, BMD gradually decreases with age in both sexes. The image contrast of radiographs of bones varies with the change in BMD owing to the changes in the X-ray absorption of bone. The image contrast of bone generally is higher in the young adult than in the older adult. To examine the relation between BMD and image visibility, we carried out the following experiments. (1) We measured the image contrast of radiographs of a lumbar vertebra phantom in which BMD was equivalent to the average BMD for each developmental period. (2) We examined image visibility at various levels of imaging contrast using the Howlett chart. The results indicated that differences in BMD affect the image contrast of radiographs, and, consequently, image visibility. It was also found that image visibility in the young adult was higher than that in the older adult. The findings showed that, in digital radiography of young adults with high BMD, X-ray exposure can be decreased according the ratio of improvement in image visibility.     

Quantitative CT for determination of bone mineral density: a review

One of the major uses of quantitative computed tomography (CT) has been the measurement of bone mineral density (BMD) at various skeletal sites. The published literature on this subject from 1974 to the present is extensive. Because many investigators and clinicians are just now starting to explore the utility of this technique, the author reviewed this literature to provide both the historic perspective and current status of BMD measurement with CT. The physical and physiologic bases of the method, accuracy, reproducibility, radiation dose, and clinical utility are all discussed.     

定量CT在骨密度测量中的应用

骨质疏松症已逐渐成为全社会日益关注的医疗问题之一,早期的诊断对其疾病本身的治疗和骨折等并发症的预防至关重要.目前,许多骨密度(BMD)测量方法已广泛地用于骨质疏松的诊断、骨折危险性的预测和骨量变化监测的研究和临床工作中.定量CT(quantitative computered tomograpy,QCT)测量即为众多BMD测量方法之一,这是一种依赖临床CT机和特有的体膜(phantom)进行BMD测量的方法.     

应用定量CT测定胸椎骨矿密度

目的对行心脏CT检查的病人应用定量CT进行胸椎骨矿密度(BMD)测定,获得标准值,并将该值(来自各亚组)与行腰椎定量CT检查所获得的骨矿密度值进行比较。材     

Three-dimensional quantitative CT of the proximal femur: relationship to vertebral trabecular bone density in postmenopausal women

Dual-photon absorptiometry (DPA) of the proximal femur cannot independently measure cortical and high-turnover cancellous bone. In this investigation, integrated cancellous, cortical, and total bone densities in the femoral neck and intertrochanteric region were measured bilaterally in 22 women aged 42-75 years. Contiguous section data were analyzed with two different protocols by means of three-dimensional histogram software. Single-section quantitative computed tomography (CT) was used to determine mean mineral equivalent values for vertebral cancellous bone from T-11 to L-3 in each woman. Significant correlation was found between cancellous bone density at the two sites, as well as between total femoral and vertebral measurements. Femoral cortical bone density was predicted less well by means of the vertebral cancellous data. Cortical, cancellous, and total proximal femoral density values tended to exhibit bilateral symmetry. Quantitative three-dimensional volumetric CT affords comprehensive evaluation of proximal femoral mineral status because of its capability for selective measurement of cortical, cancellous, and total bone density.     

Effect of Paget's disease of bone on areal lumbar spine bone mineral density measured by DXA, and density of cortical and trabecular bone measured by quantitative CT

Although bone density may be increased in bone that is affected by Paget's disease, density changes in cortical and trabecular bone and the effect on bone that is apparently unaffected by Paget's disease are relatively unexplored. We have investigated 81 vertebrae (28 affected, 53 unaffected) in 27 patients with Paget's disease, by dual X-ray absorptiometry (DXA) and by quantitative CT (QCT) bone density measurements of trabecular and cortical bone. DXA bone density was high (mean z-score = 1.62, p < 0.001) in vertebrae affected by Paget's disease, but not significantly different from normal in unaffected vertebrae (mean z-score = 0.07, ns). Mean QCT z-score in Paget's vertebrae was 2.07 (p = 0.009) for cortical bone and 1.37 (p = 0.008) for trabecular bone. DXA correlated with QCT cortical values in affected and unaffected bone (r = 0.8 and 0.56, respectively), and with QCT trabecular values (r = 0.72 and 0.48, respectively). There was no significant difference in the slopes for the correlations in affected or unaffected bone. Cortical QCT values are underestimated in Paget's disease compared with physical measurements of density, owing to the computer algorithm used. High DXA values may alert to the possibility of Paget's disease, especially if the value deviates from the expected normal sequence in lumbar vertebrae. Osteoporotic vertebrae may be overlooked if the average value of bone mineral density is taken in the lumbar spine without reviewing each vertebra.     

Assessment of vertebral bone mineral density using volumetric quantitative CT

PURPOSE: The purpose of this work was to determine the precision and diagnostic efficacy of bone mineral density (BMD) measures based on volumetric quantitative CT (QCT) of the spine. METHOD: Volumetric CT scans of L1 and L2 (GE-9800Q; 80 kVp, 140 mAs, 3 mm slices) were acquired in a cohort of 62 osteoporotic women (mean age 70.4 years, T(DXA hip or spine) < -2.5), of whom 20 had vertebral fractures and 42 were nonfractured control subjects. An image analysis technique delineated trabecular, cortical, and integral regions in reference to a vertebra-fixed coordinate system. We computed precision values and fracture control differences for these new regions and for single-slice QCT and dual X-ray absorptiometry (DXA) measures synthesized from the volumetric data. RESULTS: Volumetric trabecular BMD showed higher precision (1.3%) than the synthesized single-slice measures (2.1-2.8%). Volumetric and single-slice trabecular BMD showed equivalent decrements between fractured and nonfractured subjects (17-19%), with integral BMD showing smaller and less significant differences (7-8%). CONCLUSION: Volumetric and single-slice QCT techniques are equivalent for vertebral fracture risk estimation, but volumetric techniques should be superior for monitoring therapy efficacy.     

Trabecular bone density in the proximal femur: quantitative CT assessment. Work in progress

A new technique has been developed for quantitative assessment of trabecular bone content in the proximal femur using computed tomography (CT). The method employs the same contoured calibration phantom currently used for vertebral mineral studies and can be performed on any standard body scanner. Both femurs are evaluated simultaneously, and an integral approach to mean density determinations compensates for the complex geometry and trabecular architecture of the region. Specimen studies have documented acceptable reproducibility, and radiation dose and examination time are comparable to those of quantitative CT in the spine. Greater inherent accuracy has been achieved more rapidly through the addition of three-dimensional histogram analysis using a free-standing CT data processor. High correlation with vertebral trabecular bone content has been documented in the limited number of patients studied to date. Widespread availability of the technique and the high frequency of fractures related to metabolic bone disease in the proximal femur render the method a potentially valuable contribution to noninvasive bone densitometry.     

我国定量CT骨量测量的临床评估

骨质疏松症是老年人常见的骨关节疾患,其骨折并发症严重地影响老年人的生活质量.为了早期预防骨质疏松症及其并发症,各国相关学者均对此给予了极大的关注,特别是对骨质疏松症诊断的骨矿含量测量进行了大量的研究工作.     

CT bone density analysis of low-impact proximal femur fractures using Hounsfield units

AimTo quantify and compare changes in bone mineral density (BMD) via CT analysis in patients with and without spontaneous femoral fractures.Materials and methodsConsecutive series of patients with CT imaging for spontaneous femoral fractures were compared to the age and gender matched controls. Bone density fixed region of interest measurements were obtained at the site of the fracture, proximally at the femoral head, and distally at the lesser trochanter in fracture patients and controls. Inter- and intrapatient comparisons were performed, including Chi-square and t-test analyses.Results24 spontaneous fractures and 25 controls were analyzed with no significant differences in mean age, gender, or body mass index. There were differences in the bone density between the fracture and contralateral non-fracture sides at (p = 0.0001) and distal (p < 0.0001) to the fracture. Proximal and distal bone density differences existed between case fracture and control non-fracture sites (p < 0.0001, p = 0.0001), and between the case non-fracture and control non-fracture sites (p < 0.0001, p < 0.0001). The reliability for measurements was good to excellent proximally (ICC = 0.63–0.87), moderate to excellent at the fracture site (ICC = 0.43–0.78), and fair to good distal (ICC = 0.24–0.68) to the fracture site.ConclusionPatients with spontaneous femoral fractures exhibit lower bone density than the asymptomatic controls. Bone insufficiency is best demonstrated proximal or distal to, rather than at the fracture site.     

骨密度定量CT测量用固体标准件的研究

目的报告一种自制骨矿密度ＣＴ测量固体标准件。方法使用聚乙二醇塑料和骨基质加工成固体标准件，其两部分Ｘ线衰减特性分别相当于水和骨组织，体积为３０．０ｃｍ×９．０ｃｍ×２．５ｃｍ，重量为０．７ｋｇ。对１２个椎骨标本灰化进行标准性测试。结果骨密度定量ＣＴ（ＱＣＴ）测量结果和灰化标本灰重值相比准确性为８．６％，二者间具有非常显著相关性（ｒ＝０．９１，Ｐ＜０．００１），标准件的精确性为１．１％和０．１％。结论本组固体标准件质量可靠，为国内ＱＣＴ骨密度测量提供了一种新的更准确、可靠的工具     

Spinal bone mineral density by quantitative CT in a normal Italian population

The purpose of this study was to describe the normal cross-sectional pattern of spinal bone loss associated with aging in an Italian population and to compare these values to the American normative database. A group of 472 healthy subjects (382 females and 90 males) were recruited for bone mineral density (BMD) assessment by quantitative computed tomography (QCT). To eliminate technique-related differences in a comparison of Italian and American normal values obtained with two different scanners we performed a cross-calibration analysis scanning the same computerized imaging reference system (CIRS) phantom at both centers. The results of the cross-calibration study using the CIRS phantom were used to compare regression slopes of BMD with age and age-adjusted mean BMD of American men and women vs cross-calibrated Italian men and women. American men and women decrease more rapidly vs Italian men and women, and Italian men have significantly lower age-adjusted mean BMD than American men. For these reasons we recommend normal values to be locally obtained for an Italian population. Correspondence to: G. Guglielmi