Prevalence and characteristics of paratracheal air cysts and their association with emphysema in a general population

Background

To evaluate the prevalence and characteristics of paratracheal air cysts and their association with emphysema and gender in a general population using low-dose computed tomography scanning of the chest.

Materials and methods

We retrospectively enrolled a total of 924 patients (584 women, 340 men; mean age, 59.73 years; range, 37–89 years) who had received low-dose computed tomography scanning for health examination during the period January 1, 2010 to June 30, 2010. Computed tomographic images were evaluated for the presence of paratracheal air cysts. If paratracheal air cysts were identified, the lungs were reconstructed as a three-dimensional model on a commercial workstation. An emphysema index, an objective quantification of the extent of emphysematous changes on CT imaging, was defined as the percentage area of lung with attenuation values below −950 Hounsfield units.

Results

A total of 60 patients with paratracheal air cysts were included in this study (estimated prevalence, 6.5%; 12 men, 48 women; mean age, 59.85; range 45–89 years). Emphysema index differed significantly between genders (P < 0.0001). The prevalence of paratracheal air cysts in men was significantly lower than that in women (P = 0.005); however, the emphysema index in patients of both genders showed no evidence of emphysema. The majority (95%) of paratracheal air cysts were at the level of the seventh cervical to the second thoracic vertebrae.

Conclusion

The presence of paratracheal air cysts is a common condition in general populations and should not be misdiagnosed as abnormal paratracheal free air. Paratracheal air cysts are more common in woman than in man. In our study, there is no patient with paratracheal air cysts has CT evidence of emphysema.     

Forearm bone mineral density in an unselected population of 2,779 men and women—The HUNT Study, Norway

The fracture incidence in Norway is among the highest in Europe, presumably due to osteoporosis. As part of a multipurpose health study in the county of Nord-Trøndelag, Norway (the HUNT study), a 5% randomly selected sample (n=4,646) of the population >19 years of age was invited to undergo single X-ray absorptiometry (SXA) of the forearm. A total of 1,274 men (50.5 years) and 1,505 women (49.9 years) participated (60%). The aim of the study was to describe the variation in bone mineral density (BMD) and the prevalence of forearm BMD 2.5 standard deviations (SD) below the mean value for young adults in an unselected population sample. In women the BMD remained stable until the age of 50 years, whereupon a strong decline in BMD was observed. In men, a BMD increase was observed until about the age of 40 years; the decline after the age of 65 was, however, similar to that in women. Based on age and gender-specific reference values, the age-adjusted prevalence of T-scores <–2.5 SD in women and men aged 50–69 years was 16.0% and 5.6%, respectively. In the age group of 70 years or older the prevalence was 65.8% and 30.6% for women and men, respectively. The accelerated BMD reduction in women aged 50–65 explains the higher prevalence of T-score <–2.5 SD in elderly women than in men. Further studies on bone loss and falls are required to explain the high fracture incidence in Norway.     

大鼠股骨骨折愈合中双能X线吸收法和组织学观察

目的 动态观察大鼠骨折愈合过程中骨折端的骨密度和组织学变化,探讨双能X线吸收法(DEXA)监测骨折愈合的作用。方法 60只3月龄,雌性SD大鼠,手术方法建立右股骨骨折模型,于术后2、4、6、8、10、12周截取双侧股骨。用双能X线吸收法作骨折端和干骺端骨密度测定,对侧股骨相同位置测量以作对照。同时对骨折端骨痂进行组织学观察。结果 骨折端平均骨密度值随时间变化递增,显示了一个明确的骨折愈合趋势。术后2、4、6、8周时分别为对侧股骨相应区域的29．5％、48．3％、85．3％、105．2％,各组差异明显。骨密度值的升高与骨痂组织的产生、钙化在时间上有一致性。干骺端骨密度在术后持续降低,到12周时尚未见回升迹象。结论 骨折端的骨密度变化与骨折端骨痂的组织学变化有一致性,骨密度能准确、定量地反映骨痂组织的钙化程度。用DXEA监测骨折愈合具应用前景。     

MR扩散加权成像评估椎体骨量状况的初步研究

目的 探讨椎体MR扩散加权成像(DWI)测量值与双能X线(DXA)、定量GT(QCT)所测骨密度的相关性.方法 152例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～L4)DXA和QCT骨密度测量;腰椎常规行MR矢状面T2 WI、T1 WI和横断面T2 WI扫描;MR常规扫描结束后采用单次激发自旋回波平面回波扩散加权序列(SS-SE-EPI DWI)[扩散敏感因子(b)=500 s/mm2]进行L2～L4椎体横断面DWI扫描,并使用GE-Functool分析软件测量相应椎体表观扩散系数(ADC值).计量资料间的相关性采用Pearson相关分析.结果 随年龄增加,椎体ADC值呈逐步降低趋势.L2～L4椎体平均ADC值(0.241×10-3 mm2/s)与相应椎体平均骨密度DXA(I.038 s/cm2)、QCT(104.2 mg/cm3)具有相关性(r值分别为0.461、0.731,P值均＜0.01).结论 DWI可在常规2腰椎MRI基础上无创性评估椎体骨髓变化状况,进而来评估骨髓的变化对于骨量状况所带来的影响.     

Accuracy and Precision of 62 Bone Densitometers Using a European Spine Phantom

Dual-energy absorptiometry (DXA) is widely used for bone mineral density measurements. Different types of devices are available. Differences between devices from either the same manufacturer or different manufacturers can lead to difficulties in clinical practice when patients are followed on different machines. We calculated the accuracy and precision of 62 DXA devices from two manufacturers (51 Hologic, 11 Lunar) using a European Spine Phantom (ESP, semi-anthropomorphic). The ESP was measured 5 times on each device without repositioning. Accuracy was assessed by comparing bone mineral density (BMD, g/cm²) values measured on each device with the actual value of the phantom. Precision was assessed by the coefficient of variation (CVsd), using the root mean square average. The limits of agreement were estimated from the differences between each replicate measurement of BMD and the estimated true value for a particular manufacturer, according to Bland and Altman. The results confirm the difference between devices from different manufacturers (18.5%). Mean CVsd values were 0.57% and 0.64% for Hologic and Lunar respectively. The limits of agreement among devices from the same manufacturer were 0.026 g/cm² and 0.025 g/cm² for Hologic and Lunar respectively. Differences in extreme results between devices from the same manufacturer were on average 5.4% and 3.6% for Hologic and Lunar respectively. Results of different devices from the same manufacturer are highly comparable, although unpredictable differences exist that may be clinically relevant. Received: 12 June 1998 / Accepted: 20 November 1998     

Comparison and Cross-Calibration of DXA Systems: ODX-240 and Sophos L-XRA versus Hologic QDR-4500, for Spinal Bone Mineral Measurement. Translation of a Reference Database

Replacement of dual-energy X-ray densitometry equipment may be necessary in time as a result of upgrading systems or new equipment. The lack of standardization in bone mineral density (BMD) measurements is known. Standardization efforts have been made for several years by the European Union under its organization COMAC-BME (Comité d'Actions Concertés–BioMedical Engineering) and by the International Committee for Standards in Bone Measurement. Cross-calibration is generally considered to be the result of linear regression between the measurements obtained with two densitometers. A major disadvantage of the regression method is the noncompatibility of the two formulae of calibration (Y versus X and X versus Y). In this study we considered cross-calibration in terms of a structural model that produced circular equations when, for example, three systems were cross-calibrated. Cross-calibration in this study was calculated from the measurement of the lumbar BMD of a population of 204 patients, with Hologic QDR-4500, ODX-240 and Sophos L-XRA systems. In vitro accuracy and short-term reproducibility of the three systems were studied. Using the structural calibration equation we transformed a reference database for L2–4 BMD obtained from a population of 983 French females, aged 11–47 years, on an ODX-240 to a reference database for a Hologic QDR-4500. A new young adult reference was obtained and consequently a new evaluation of the T-score for the Hologic QDR-4500. Received: 17 July 1997 / Revised: 9 March 1998     

The on-line characterization of a radium slurry by gamma-ray spectrometry.

We have developed an in-line monitor to directly measure the ²²⁶Ra concentration in a nuclear waste stream using quantitative gamma-ray spectrometry applied to the 186 keV emission. The waste stream is in the form of a slurry composed of the solid waste material mixed with water. The concentration measurement includes a self-attenuation correction factor determined from a transmission measurement using the 122 keV γ from ⁵⁷Co. Presented here is the model for the measurement system and results from some initial tests.     

骨疏松性骨折的定量CT预测

笔者分析了６３例女性骨疏松病例的脊椎平片及ＱＣＴ检查。６３例中伴骨折者２９例。骨折组的椎骨骨矿密度（ＢＭＤ）明显低于无骨折组者（Ｐ＝０．０００６）。笔者认为，以椎骨ＢＭＤ测值９５ｍｇ／ｃｍ￣３作为骨折阈值更适用于中国老龄妇女。６３例中有异位钙化者１８例。有及无异位钙化组的椎骨ＢＭＤ值有显著性差异（Ｐ＜０．０５），ＢＭＤ值越低，发生异位钙化的机会越大。笔者提议把异位钙化作为判断骨疏松的提示性征象。     

新疆汉维哈3个民族骨密度正常值测量结果及其差异性分析

目的　分析新疆汉、维吾尔、哈萨克 3个民族正常人群骨密度值测量结果及其差异性 ,确定本地区各民族骨密度正常值 ,为开展骨质疏松症防治工作提供判断骨密度的依据。方法　对年龄 2 0～ 6 5岁来自新疆汉维哈 3个民族正常人群的 1340名个体进行腰椎骨密度测量 ,按 5岁一个年龄段分别统计出均数和标准差 ,并且进行 3个民族同性别、同年龄之间骨密度差异性的分析。设备为TomoscanSR 70 0 0螺旋滑环式CT机 ,配合使用QCT 30 0 0骨密度测量系统 ,对所有调查对象的腰椎 2～ 4椎体松质骨进行测量和计算。结果　 (1)新疆汉维哈 3个民族男性的骨密度峰值分别为184 0 4± 34 34、2 2 5 18± 14 6 5、2 4 0 16± 31 4 9mg cm ,女性的骨密度峰值分别为 174 0 4± 34 2 4、180 37± 32 4 5、2 0 0 92± 38 77mg cm。 (2 ) 3个民族男性骨密度的峰值年龄段分别是 2 0～ 2 5岁、30～35岁、2 5～ 30岁 ,而女性骨密度的峰值年龄段分别是 30～ 35岁、2 5～ 30岁、2 0～ 2 5岁 ,骨密度到达峰值后随着年龄的增加而下降 ;(3) 3个民族男性各个年龄段的骨密度值经方差分析全部P <0 0 5(0 0 17～ 0 0 3) ;而 3个民族女性除了 5 0～年龄段P =0 1180外 ,其余各个年龄段均P <0 0 5 (0 0 0 4～ 0 0 4 )。结论　新疆汉维