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.     

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.     

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     

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.     

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     

Relationships of cervical, thoracic, and lumbar bone mineral density by quantitative CT

PURPOSE: The purpose of this work was to compare, using quantitative CT (QCT), vertebral bone mineral density (BMD) in the cervical, thoracic, and lumbar spine in healthy volunteers. METHOD: QCT of the vertebral bodies of C2, C5, T12, and L4 was performed on 50 healthy volunteers (25 women, 25 men; mean age 31.7 years). Trabecular BMD analysis was performed at each level. RESULTS: Mean BMDs (mg/cm3 calcium hydroxyapatite) for women and men were highest at C5 (BMD women/men 341.6/300.6 mg/cm3) and C2 (297.2/269.6 mg/cm3) and lowest at T12 (193.1/184.9 mg/cm3) and L4 (186.2/180.1 mg/cm3). The BMD of C2 was statistically significantly different from that of C5, T12, and L4 (p < 0.0001) for both genders. Also, the BMD of C5 differed significantly from that of T12 and L4 (p < 0.0001). The BMD of C5 showed significant gender differences (p = 0.002). Correlation coefficient showed a strong correlation between the BMD of T12 and L4 for both genders (women, r = 0.67; men, r = 0.90). CONCLUSION: Trabecular BMD of C2 and C5 measured by QCT is significantly higher than trabecular BMD of T12 and L4 in nonosteoporotic volunteers of both genders.     

应用定量CT骨测量技术评价骨密度与静脉注射造影剂间的关系

目的通过定量CT骨检测(QTC),评估受试者注射增强造影剂前后骨密度(BMD)的变化。方法自2014年5月至2015年3月,共166例患者(其中106例无肾癌者,60例肾癌患者),同时接受腹部CT扫描,通过测量腰1椎体的CT值,记录三期(平扫、动脉期及静脉期)的骨密度(BMD)变化。结果注射增强剂的两组(动脉期及静脉期)CT衰减值比无注射组(平扫期)显著增高(P<0.01)。无肾癌组:增强组动脉期CT值由(127.6±46.3)HU增长至(141.2±46.2)HU,静脉期增长至(146.3±47.1)HU(P<0.01)。肾癌组:增强组动脉期CT值由(113.2±37.8)HU增长至(125.2±38.2)HU,静脉期增长至(131.2±36.1)HU(P<0.05)。结论 QCT对有肾癌组及无肾癌组患者进行三期(平扫、动脉期及静脉期)骨密度检测,注射增强造影剂均大幅度增加骨衰减,因此,造影剂对CT检测骨质疏松程度存在干扰,提示临床诊断骨质疏松症时须将造影剂的影响考虑在内。     

Hematopoietic bone marrow hyperplasia: high prevalence on MR images of the knee in asymptomatic marathon runners.

In a prior study of marathon runners, we noticed that MR scans of the knee frequently showed hyperplasia of red (i.e., hematopoietic) bone marrow. Because the frequency of this finding in various populations is unknown, the purpose of this study was to determine the relative prevalences of hematopoietic bone marrow hyperplasia on MR examinations of the knees of healthy volunteers (n = 74), patients with symptoms of knee disorders (n = 54), and asymptomatic marathon runners (n = 23). The prevalence of hematopoietic bone marrow hyperplasia was 3% (2/74) for the healthy volunteers, 15% (8/54) for the patients, and 43% (10/23) for the marathon runners. The difference in prevalence between each of the three groups was statistically significant at p less than .05 in each case with hematopoietic bone marrow hyperplasia, the distal femur was the only area affected, while the epiphysis and proximal tibia were uninvolved. This pattern of affected bone marrow with hyperplasia of the hematopoietic marrow may be useful for the differential diagnosis. We postulate that the high prevalence of hematopoietic bone marrow hyperplasia in marathon runners may develop as a response to "sports anemia", which is commonly found in highly conditioned, aerobically trained athletes. Furthermore, this is considered to be a normal variant when found in the pattern described here.     

绝经后妇女腰椎骨密度容积性定量CT测量研究

目的 应用容积性定量CT(vQCT)技术和双能X线吸收测量(DXA)仪测量绝经后妇女腰椎容积性骨密度(BMD),评价2种检查方法区分骨质疏松伴椎体骨折与骨质疏松不伴骨折的差异.方法 选取绝经后妇女118名[平均年龄(62.1±7.0)岁],按照所行胸腰椎X线平片检查结果及腰椎DXA测量的参数[前后位BMD(AP-SPINE)]值分组,>均值-1个标准差(x-1s)为正常组、x-1s～x-2s为骨量减少组、0.05).在骨质疏松组和骨质疏松伴骨折组AP-SPINE仅与3D-CORT间有相关性(R2=0.189,P<0.01);App60 BV/TV%、App80 BV/TV%、App100 BV/TV%、App120 BV/TV%与3D-TRAB或2D-TRAB之有相关性(3D法:R2值分别为0.955、0.951、0.941、0.912;2D法:R2值分别为0.912、0.910、0.878、0.821;P值均<0.01).容积性BMD的测量精确度为0.70%～2.25%.结论 vQCT技术可区分骨质疏松及伴骨质疏松性骨折绝经后妇女骨量,能力高于DXA,其中整体骨BMD诊断严重骨质疏松的效果最好;App BV/TV%可反映骨质疏松者骨小梁丢失程度,预测骨折风险.     

Lifestyle questionnaire to evaluate risk for reduced bone mineral density in women.

OBJECTIVE: To determine the contribution of various risk factors to quantitative ultrasound parameters in a sample of women, and to develop a tool to assess osteopenia risk, with a view to targeted early intervention. DESIGN: Questionnaire study. SETTING: A local center comprising a fitness center, conference center, and administrative offices for various businesses and sports. PATIENTS OR PARTICIPANTS: A convenience sample of 187 Caucasian women who volunteered as part of a free public health screening initiative. MAIN OUTCOME MEASUREMENTS: A questionnaire was designed to collect data on history of osteoporosis, current physical activity, calcium, alcohol and caffeine intakes, smoking, and various reproductive measures. Historical physical activity data were also collected, and lifetime energy expenditure and impact scores were calculated. Quantitative ultrasound was performed on the left calcaneus. Odds ratios (ORs) were calculated to determine the odds of being osteopenic (T-score < or =-1 SD) against not being osteopenic (T-score >-1SD), due to exposure to the aforementioned risk factors. RESULTS:: Significant ORs were obtained for age (OR: 1.042; 95% CI: 1.016-1.068), current physical activity (> or =3 times/wk; OR: 0.320; 95% CI: 0.140-0.732), and lifetime energy expenditure score (OR: 0.957; 95% CI: 0.926-0.989). A regression model based on age and current physical activity correctly identified 57% of women with or without osteopenia. CONCLUSIONS: Although the model we developed was not sensitive or specific enough to assess osteopenic risk accurately, the results show that frequency of physical activity, independent of age, is an important lifestyle factor to consider when quantifying osteopenic risk.     

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.     

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.     

Characterization of atherosclerotic plaque components by high resolution quantitative MR and US imaging

High resolution MRI at 3 T and US imaging at 50 MHz were used for atherosclerotic plaque characterization. For 14 excised segments of human arteries, conventional MR and US images, quantitative MR T2 maps, US integrated attenuation (IA) maps, and histologic sections were produced and compared. The MR T2 and US attenuation mean values estimated in selected regions of interest were related with tissue type as identified on histologic sections. Significant distinction between media or collagen and lipid or collagen lipidic plaque was achieved with both techniques (MR: P < .001; US: P < .01). Significant distinction was obtained between media and collagen (P < .0001) and between iliac and aortic media (P < .05) with MR T2 but not with IA. MR and US native and parametric images, with different sensitivities to tissue type, provide complementary information useful for quantitative plaque characterization.     

CT of the middiaphyseal femur: cortical bone mineral density and relation to porosity

PURPOSE: To determine whether computed tomography (CT) can be used to quantify age- and site-related changes in cortical bone mineral density (cBMD) at the middiaphyseal femur and whether cBMD differences are related to intracortical porosity. MATERIALS AND METHODS: Cortical bone specimens from 163 femurs were studied with CT and microradiography. Femurs were from 77 males and 86 females in a white anthropologic collection covering a broad age spectrum. In each sample, the cBMD was measured in the entire cortical width and in periosteal, midcortical, and endosteal subregions of interest. Age- and site-related changes in cBMD were tested for significance by using a two-way analysis of variance for both sexes. By using linear regression, cBMD was compared with porosity in the entire cortical width and in each subregion. RESULTS: There were significant age-related differences in cBMD (P <.001 in females, P =.008 in males). In addition, cBMD values were significantly different between the three cortical subregions (P <.001 for both sexes), decreasing from the periosteum to the midcortex to the endosteum. The cBMD values were closely related to porosity, and porosity contributed to 71.6% of the variance in cBMD in the overall population. CONCLUSION: CT is effective in the measurement of age- and site-related changes in cBMD. Decreases in cBMD are closely correlated with increased cortical porosity.     

Axial and appendicular bone mineral content determined by computed tomography. Relationship to age and body size in males

Bone density and mass related values were determined in femoral condyles and in the second lumbar vertebra in males of middle age. A poor agreement was found between measurements in the two locations. The measurements were compared with age and body size by means of correlation analysis and multiple regression analysis. There was a significant linear relationship between lumbar measures and age (beta coefficient -0.61 and -0.75) while the relationship with age for the femoral measures was less (beta -0.36 and -0.45). For all measurements there was a poor correlation with body size (weight, length and surface area). Bone mineral content measurements in the lumbar and appendicular skeleton have different clinical implications. When selecting a method for estimating the bone mineral content careful attention must be paid to what type of information is wanted and whether the method is adequate for that particular purpose.     

Assessment of the bone mineral density in the lumbar vertebrae of newborns by quantitative computed tomography

 Objective. To assess the true mineral density (BMD, in g/cm³) of the lumbar spine in newborns. Design and patients. A post-mortem analysis of five infants with gestational ages ranging from 35 to 40 weeks, and birth weights from 2765 to 3200 g, was conducted using dual-energy quantitative computed tomography (QCT; Siemens Somatom DR). A 2 or 4 mm thick slice was obtained for each lumbar vertebra from L1 to L4. The density measured in these vertebrae was corrected by reference to a solid phantom (Osteo-CT) measured simultaneously. A three-dimensional image of the spine (Elscint CT Twin), as well as a photomicrograph of histological preparation from L2 vertebra, were also obtained in another term baby for comparison with the CT results. Results and conclusions. In the range of values studied, the vertebral densities were not dependent on birth weight. BMD values measured in L2, L3 and L4 were not significantly different, but were 10% lower than in L1 in four of five infants. The spatial resolution of the QCT protocol used (0.4 mm) did not permit the differentiation of trabecular and cortical bone, and the vertebral bodies appeared very homogeneous and dense, with a mean density value of 210±30 mg Ca/cm³, which is 2.5 times higher than the mean maximum value found in young normal adults. These preliminary results highlight the potential of QCT in neonatology. Special protocols will, however, need to be developed for in vivo measurements in this particular paediatric field.