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.     

Evaluation of bone mineral density with dual energy quantitative computed tomography (DEQCT)

Quantitative computed tomography (QCT) has been found useful in the evaluation of vertebral bone mineral density (BMD). It separates cortical from trabecular bone in the vertebral bodies. The accuracy of QCT, however, is limited because of the existence of unknown amounts of marrow fat in the trabecular bone. The purpose of this study is to investigate the precision and accuracy of QCT, with a particular emphasis on the advantage of dual energy technique over single energy technique, as well as to investigate age-related change of BMD in patients with no metabolic disorders. For evaluation of BMD, SOMATOM DR-H CT scanner was used, which provided dual energy scan with rapid kilovolt peak switching system. The lumbar vertebrae (L1-L3) were exposed at the middle portion together with the calibration phantom (Ca10(PO4)6(OH)2 200 mg/ml, 0 mg/ml). KV-separated images (KV-HI, KV-LO) and material-separated images (MAT-HI, MAT-LO) were calculated from dual-energy scan data. KV-separated data were considered as SEQCT data. In experiment, dipotassium hydrogen phosphate (K2HPO4) solution was used to simulate bone mineral, water to simulate lean soft tissue and ethanol (C2H5OH) to simulate fat. To investigate the variations originating from marrow fat, a series of phantoms (K2HPO4-C2H5OH-H2O mixtures) with a constant 10 gm% K2HPO4 concentration but with the various mixtures of C2H5OH ranging from 0-40% by volume was scanned with dual energy technique. The value of BMD obtained from KV-separated data was reduced about 12% per 10% fat by volume increase, while the value obtained by DEQCT technique was reduced 5.5% per 10% fat by volume increase. With the dual energy technique the error was greatly reduced. On the other hand, the higher precision of KV-separated images compared to MAT-HI images was obtained, as well as the relatively higher precision for determining high rather than low fraction of mineral. In conclusion, with the single energy technique, precision is high, and with the dual energy technique, accuracy is high. It was also noted that selection of the CT section was the most critical factor in clinical BMD analysis. Age-related change of BMD in vertebral trabecular and cortical bone was studied in 161 patients without bone metabolic disorders. There were two peaks of BMD in females in their 20s and 30s, and a single peak in males in their 20s.(ABSTRACT TRUNCATED AT 400 WORDS)     

Vertebral mineral determination by quantitative computed tomography (QCT): accuracy of single and dual energy measurements

Quantitative CT (QCT) studies of trabecular vertebral bone tissue have been carried out in vitro on a GE CT/T 9800 scanner. Results of both single energy (SE) 80 kVp and dual energy (DE) 80/140 kVp QCT data are compared with chemical mineral analysis to determine accuracy. We examined 62 vertebral specimens, from 28 cadavers (19 male and 9 female with an age range of 19-93 years, mean = 60.4). Averaging the results of all vertebral bodies of the same individual for SEQCT versus ashweight, we found a correlation coefficient (r) of 0.94 (p less than 0.0001), a standard error of the estimate (SEE) of 12.2 mg/cm3 (calibrated to K2HPO4), with a coefficient of variation (CV) of 13.2% and an average underestimation of bone mineral content of 18.7 mg/cm3. The corresponding DEQCT results were r = 0.98 (p less than 0.0001), SEE = 7.4 mg/cm3, CV = 7.0%, and an average underestimation of 4.9 mg/cm3. The SE and DE results are correlated with r = 0.98 (p less than 0.0001), SEE = 8.0 mg/cm3, and CV = 8.7%. From our SEQCT data and the results of the chemical analysis of bone mineral and fat content we calculated a fat sensitivity of 7.7 mg/cm3 K2HPO4 per 100 mg/cm3 fat change for our scanner. Using an average fat variability of 87.5 mg/cm3, this leads to a fat-related uncertainty for the normative SEQCT data of 6.7 mg/cm3, which is far lower than the normal biological variation of 29.4 mg/cm3. Using tabulated normative data on fat content versus age and versus mineral content of 188 vertebral specimens from five collaborating centers, we derived a correction algorithm for QCT measurement that reduces our average underestimation to 0.88 mg/cm3 with an SEE of 12.1 mg/cm3. Hence, this correction procedure can be used to estimate the fat corrected absolute mineral density for research purposes or for scanners with high fat sensitivity. For the GE CT/T 9800 scanner, with a relatively low fat to mineral sensitivity at 80 kVp, the correction procedure is generally not recommended for clinical studies since it minimizes the average fat induced error but does not reduce the residual, partially fat related uncertainty. Finally, since the fat related uncertainty is small compared to biological variation, the correlation is high between SEQCT and DEQCT, and the radiation dose is lower and the precision higher for SEQCT, we suggest that most clinical diagnostic studies using the GE CT/T 9800 scanner for bone mineral determination employ SEQCT at 80 kVp.     

正常人腰椎骨密度不同测量方法的比较分析

目的比较腰椎骨密度不同测量方法的异同点,旨在为合理地应用各种腰椎骨密度仪。方法应用定量ＣＴ（简称为ＱＣＴ）和双能Ｘ线骨密度仪（简称为ＤＸＡ,其中包括椎体正位测量,简称为ＰＡＤＸＡ;侧位全椎体测量,简称为ＬＤＸＡ;侧位椎体中部测量,简称为ＭＬＤＸＡ）测量了４４３例正常人腰椎的骨密度,其中男１８９例,平均年龄４６．９岁;女２５４例,平均年龄４５．７岁。结果ＱＣＴ和ＰＡＤＸＡ的重复性明显优于ＬＤＸＡ和ＭＬＤＸＡ;年下降率和骨密度线性丢失均以ＱＣＴ最为明显;无论男女,ＱＣＴ峰值出现最早,其次是ＭＬＤＸＡ和ＬＤＸＡ,ＰＡＤＸＡ峰值出现最晚;各种测量方法的相关性与所测的结构是否相似有关。结论腰椎各种骨密度测量方法各有其特点,各种测量方法仍不能互相取代。     

Assessment of geometric, biomechanical, and osteodensitometric properties of the ultradistal radius with peripheral quantitative computerized tomography in uremic patients with severe hyperparathyroidism]

INTRODUCTION: Bone integrity and mineral status were studied with a noninvasive method in uremic patients with severe secondary hyperparathyroidism undergoing maintenance hemodialysis. MATERIAL AND METHODS: Volumetric cortical and trabecular mineral density (cBMD, tBMD) and bone geometrical properties were evaluated in 16 patients (11 women and 5 men) candidate to parathyroidectomy. Peripheral quantitative Computed Tomography (pQCT) was used to make measurements at the distal radius of the nondominant forearm. Thirty-two age-matched healthy subjects were chosen as a control group. Cortical area (CA), cross-sectional area (Total A), cortical thickness (CThk) and stress strain index (SSI) were assessed as biomechanical parameters. Serum intact PTH levels were assessed with a radioimmunoassay method (IRMA). RESULTS: Both cBMD and tBMD were decreased in all patients and the difference was more significant in women (p < .0004 and p < .009) than in the smaller group of men (p < .01 and p < .01). Serum PTH levels correlated negatively with cBMD (r = .52; p < .01), CThk (r = .51; p < .04), CA (r = .52; p < .03) and SSI (r = .54; p < .02), as well as tBMD (r = .34), though not significantly. Dialysis duration did not significantly correlate with cBMD (r = .33), tBMD (r = .20), CA (r = .31), CThk (r = .40) and SSI (r = .35). As for geometrical and biomechanical parameters, CA, CThk and SSI were significantly different in both male and female uremic patients in comparison with the relative controls. Bone quantitative analysis and three-dimensional (3D) representation with the paraboloid revolution model also demonstrated osteopenia. CONCLUSIONS: pQCT shows significant cortical and trabecular osteopenia in uremic patients with severe secondary hyperparathyroidism. Osteopenia is associated with geometrical and mechanical impairment with consequently increased bone fragility and thus a higher risk of fracture. Prolonged PTH hyperexpression seems to be mainly associated with intracortical porosity and cortical-endosteal resorption. Bone quantitative analysis and 3D representation provide rapid automated information on the cortex mineral status.     

Relationship between bone mineral density and tooth loss in elderly Japanese women.

OBJECTIVE: To evaluate the relationship between vertebral bone mass and tooth loss and jaw bone mass in elderly Japanese women. METHODS: Mandibular cortical bone mass, alveolar bone height and number of teeth present (total, anterior, and posterior) were compared with the 3rd lumbar vertebral bone mineral density (L3BMD), measured by dual energy computed tomography (DEQCT), in 90 Japanese women by means of multiple regression analysis, controlling for body mass index, menopausal status, years since menopause and self-reported periodontal condition. RESULTS: Mandibular cortical bone mass and number of posterior teeth were associated with both alveolar bone height and L3BMD, but there was no association between alveolar bone height, number of anterior teeth present and L3BMD. CONCLUSION: Our results suggest that the loss of posterior teeth may be associated with a decrease not only in alveolar bone height, but also alveolar bone mineral density (BMD). The latter may be related to a decrease of lumbar vertebral BMD.     

Accuracy of single-energy quantitative computed tomography in the assessment of bone mineral density of cervical vertebrae

Earlier studies have shown that single-energy quantitative computed tomography (SEQCT) is a reliable method for bone mineral density (BMD) measurements in thoracic and lumbar vertebrae. Moreover, SEQCT has proved to be a useful parameter in the selection of appropriate implants in cervical spondylodesis. The aim of this study was to determine the accuracy of SEQCT in cervical vertebrae BMD measurement. BMD with reference to calcium hydroxyapatite (Ca₁₀[PO₄]₆[OH]₂) was assessed by SEQCT in 100 human vertebral bodies of the cervical spine. Bone cylinders were then cut from the appropriate region of interest. The cylinder volume was determined by the liquid displacement technique. The density of the mineral component was measured following incineration at 1100 °C for 24 h. The calculated BMD was correlated with the SEQCT values, resulting in a coefficient of r = 0.79 (P < 0.01). Mean SEQCT values were significantly lower than those determined by direct density assessment (t-test for coupled sampling, P < 0.02). This result was in agreement with studies on thoracic and lumbar vertebrae. These data suggest that SEQCT can reliably measure BMD in the cervical spine. Received 12 July 1996; Revision received 17 January 1997; Accepted 10 March 1997     

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.     

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     

Age-related changes in cortical and trabecular bone mineral status. A quantitative CT study in lumbar vertebrae

Purpose: To investigate the age and sex dependence of the bone mineral status of human lumbar vertebrae with special regard to differences between cortical and trabecular bone.Material and Methods: The study group comprised 125 normal Japanese healthy volunteers (54 males and 71 females), and was subdivided into adult male and female groups (subjects younger than 40 years), intermediate male and female groups (ages ranging between 41 and 64 years) and old male and female groups (subjects older than 65 years). The cortical bone mineral status was estimated using a single-energy quantitative CT (SE-QCT) technique, whereas trabecular bone mineral density (BMD) was estimated using a dual-energy (DE-QCT) technique.Results: A considerable gender difference in the age-related cortical bone status was found. There was a significant reduction of the mean values of the cortical volume and BMD in the old female group compared with those obtained in the old male group.Conclusion: The results suggest that in men, cortical and trabecular bone volume decrease very little with age. In women, cortical volume and BMD and trabecular BMD decrease with age while trabecular bone volume does not. The study showed that all variables had higher values in men than in women and that the difference increased with age.     

CT evaluation of bone mineral density (BMD) of lumbar spine in patients after gastrectomy

The late postoperative complications in patients after gastrectomy include anemia and metabolic bone disorders. We studied to determine whether gastric surgery is associated with metabolic bone disease. Vertebral BMD was measured in 55 patients after gastric resection by using DEQCT (dual energy quantitative CT). Forty patients were symptomatic, having bone or joint pain, history of bone fracture, or dental caries. The control group consisted of 161 patients without metabolic bone disorders. Forty percent of the patients with either the symptoms or history of bone fracture or dental caries, and 20% of the patients without the symptoms or the history showed decreased BMD. BMD was significantly lower in males in their 60s and in females in their 50s and 70s than BMD in age-matched control groups. When male subjects were grouped according to the years following the operation (1-5, 6-10, 11-15, 16-20 years), BMD was found to be decreased in 27%, 29%, 40% and 50% of the patients after surgery. Higher incidence of decreased BMD was found in the patients after total gastrectomy when compared with those after subtotal gastrectomy. Among the patients with subtotal gastrectomy, the incidence of decreased BMD was higher in patients with Billroth II anastomosis than in those with Billroth I anastomosis. In cases with compression fracture on thoracolumbar radiographs, BMD was significantly lower in comparison with cases with no fracture. It was difficult to differentiate between osteomalacia and osteoporosis only by the thoracolumbar radiographs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bone mineral density in adults with Down's syndrome

The objective of the study was to elucidate if individuals with Down's syndrome (DS) are likely to experience an increased risk of osteoporosis with advancing age, in addition to precocious aging and their skeletal anomalies. Bone mineral density (BMD) was measured in 22 home-reared adults (9 males and 13 females; age 26.22 ± 4.45 and 23.65 ± 3.23 years, respectively) by dual energy X-ray absorptiometry (DXA). The BMD of the second to fourth lumbar vertebrae was measured in posteroanterior projection and the mean density expressed as grams per square centimetre. The BMD of DS individuals was compared with 27 control subjects (12 males and 15 females) of the same age (age 24.16 ± 3.46 and 23.86 ± 2.92 years, respectively). The results showed that the BMD of the lumbar spine in the males as well as in the females with DS was significantly lower than that in their control counterparts (p < 0.001). Comparing the DS males with the females, the BMD was lower in the males at a level of 9 %. Factors that contribute to this disorder may be mainly the muscular hypotonia, the sedentary lifestyle and the accompanying diseases which frequently observed in the syndrome. Future studies must be focused on the biochemistry of bone metabolism, the evaluation of gonadal, thyroid and parathyroid function, and the genes of the extra chromosome 21. Received: 24 March 1998; Revision received: 27 May 1998; Accepted: 6 July 1998     

Impact of marrow fat on accuracy of quantitative CT

An assessment of the role of marrow fat as a source of error in single energy quantitative CT (SEQCT) measurements of the spine is presented. Fat-induced shifts and spreads in SEQCT findings are discriminated and quantified. Studies using chemical analysis have reported an average vertebral bone mineral (MIN) loss of approximately 1.3 mg/ml (0.9%) per year from a peak MIN of 150 mg/ml at age 30 years with a standard error of the estimate (SEE) of approximately 23 mg/ml [coefficient of variation (CV) = 20%]; intraosseous vertebral fat content increases by approximately 2.4 mg/ml (1.4%) per year from a fat density of 175 mg/ml at age 30 years with an SEE of approximately 87.5 mg/ml (CV = 36%). If one does not adjust for the average age-related fat change, SEQCT underestimates MIN and overestimates MIN loss by 10-30% (at a scanner setting of approximately 80 kVp). Application of correction procedures reduces the average underestimation to 1-3%. The impact of residual vertebral fat variability on the accuracy of MIN measurements accounts for only 12-24% of the total accuracy error of typically 10-15 mg/ml. The impact of fat changes between zero and twice the normal age-related rate on MIN loss measurements on individual patients and patient groups (treatment versus control) accounts for only 1-2% of the total precision error of typically 1.5-3 mg/ml. From 94 to 99% of the spread of SEQCT versus age data is caused by sources of variability other than fat. All fat-related errors are higher than the above estimates by a factor of approximately 1.5-2.5 when scanning at higher voltages of up to 130 kVp. Given the limited impact of fat variability, we conclude that for most clinical applications, MIN and bone loss measurements should use SEQCT. Adjustment for the average under/overestimation (by either explicitly correcting SEQCT findings or by comparing them with normative data obtained on a similar scanner), measuring at low voltages of approximately 80 kVp, and strict compliance to quality assurance procedures are highly recommended to achieve optimum accuracy.     

The effects of swimming training on bone tissue in adolescence

The aim was to analyze bone mineral content (BMC) and density (BMD) in regular swimming trained adolescents and the interaction that weigh‐bearing sports may have on these values. Bone mass was evaluated by dual energy x‐ray absorptiometry (DXA) and quantitative ultrasound (QUS) in 77 swimmers (34 females/43 males) and 52 normoactive controls (CG; 23 females/29 males) from 11 to 18 years. Swimmers who had performed or were performing other sports (OSP; 11 females/20 males) were compared with pure swimmers (PSW; 23 females/23 males). Both groups were compared with CG. Bone values were compared using analyses of covariance adjusting for height, calcium intake, subtotal lean (whole body lean minus head), and pubertal status. Male PSW showed lower BMD and BMC at several sites than male CG. However, for male OSP, only lumbar spine BMC was lower in OSP than male CG. Male PSW showed lower BMD and BMC when compared with male OSP. Female PSW showed higher arm BMD and lower leg BMC than female CG, while female OSP only presented lower leg BMC than female CG. Contrary to males, female‐PSW presented higher BMD and BMC than female OSP. No differences in QUS values were found between swimmers and CG. To summarize, although more information is needed for females, it seems that for males, swimming is associated with lower BMC and BMD.     

腰椎能谱CT评估Graves甲状腺功能亢进症患者131I治疗前后骨量变化的价值

目的探讨能谱CT成像对Graves甲状腺功能亢进症（简称甲亢）患者骨量评估的价值,以及131I治疗对Graves甲亢患者骨量的影响。方法收集2015年6月至10月期间在我科接受131I治疗的68例Graves甲亢患者[（男性13例、女性55例,年龄（40.6±10.7）岁],治疗前采用双能X线吸收法（DXA）测定腰椎骨密度（BMD）,能谱CT测定第3腰椎钙（水）密度,采用Pearson相关分析及线性回归探讨二者的相关性。治疗后半年随访评价疗效,复查腰椎能谱CT,采用配对t检验比较131I治疗前后骨量变化。结果DXA的测定结果显示,68例Graves甲亢患者中有21例伴有骨量减少（30.9%）,7例伴有骨质疏松（10.3%）。骨量正常组患者的第3腰椎钙（水）密度为（64.33±14.65）g/cm3,骨量减少组为（48.29±4.45）g/cm3,而骨质疏松组为（41.65±1.21）g/cm3,3组间差异有统计学意义（χ2=35.811,P < 0.001）。骨量正常组患者的第3腰椎BMD为（1.252±0.305）g/cm2,骨量减少组为（1.103±0.254）g/cm2,而骨质疏松组为（0.539±0.066）g/cm2,3组间差异有统计学意义（F=12.968,P < 0.001）。Graves甲亢患者的第3腰椎钙（水）密度与DXA测定的腰椎BMD呈高度正相关（r=0.794,假设检验水准α=0.01,t=10.605,P < 0.001）。由线性回归分析得到线性回归方程:第3腰椎钙（水）密度=24.485+34.529腰椎BMD。治疗后半年随访发现,甲亢治愈组患者131I治疗后腰椎钙（水）密度较治疗前增加,骨量改善,差异有统计学意义（t=7.86,P < 0.001）;而甲亢未愈组患者较治疗前变化不显著,差异无统计学意义（t=2.29,P=0.062）。结论能谱CT测得的腰椎钙（水）密度可用于评估Graves甲亢患者的骨量。患者经131I治疗后,骨量可随着甲亢的有效缓解而显著改善。     

肾移植术后患者骨密度水平的调查研究

 目的 探讨肾移植术后患者与正常体检人群骨密度(bone mineral density, BMD)水平,以及骨量丢失(骨量减少和骨质疏松)发病率的差异。方法 选择在武警总医院随访的肾移植患者177例(男104例,女73例),根据女性是否绝经和男性年龄将入选者分为＜50岁男性、≥50岁男性、绝经前女性和绝经后女性移植组。选择同期在我院体检的正常人群250例(男131例、女119例)作为对照组。采用双能X线骨密度仪测定所有人的腰椎、右股骨颈和右全髋BMD,比较各移植组与对照组BMD以及骨量丢失发病率的差异。结果 各肾移植组患者股骨颈和全髋骨密度均低于对照组(P<0.01);＜50岁男性肾移植患者腰椎骨密度低于对照组(P<0.01)。男性和绝经后女性移植患者骨量丢失(包括骨量减少和骨质疏松)发病率显著高于对照组(P<0.01)。结论 肾移植患者骨密度水平明显低于正常体检人群,且骨量丢失的发病率高于正常人群。建议肾移植患者术后在维生素D和钙剂的基础上,选用双膦酸盐防治骨质疏松和骨折。     

中老年人群肝脏脂肪含量与骨密度的相关性研究

目的探讨中老年人群肝脏脂肪含量与腰椎骨密度的相关性。方法2016年3月至6月纳入184名北京社区中老年居民,其中男68名、女116名,对其进行腹部MRI mDIXON-Quant序列扫描和腰椎定量CT(QCT)扫描,测量肝脏脂肪含量和腰1~腰3椎体骨密度。根据肝脏脂肪含量的四分位数分为四组,采用单因素方差分析比较不同肝脏脂肪含量组间骨密度及身高、体重、体质量指数(BMI)、腰围、臀围等变量的差异,并对肝脏脂肪含量和骨密度做Spearman相关性分析和偏相关分析。结果随着肝脏脂肪含量的升高,BMI、腰围呈上升趋势,而腰椎骨密度逐渐降低。肝脏脂肪含量与腰椎骨密度呈低度负相关(r=-0.203,P=0.003),校正年龄、体重之后,仍呈负相关(r=-0.291,P<0.001),男性中r=-0.283(P=0.021),女性r=-0.210(P=0.025)。结论中老年人群肝脏脂肪含量与腰椎骨密度呈低度负相关。     

定量CT分析年龄、腹部脂肪与骨密度的关系

目的采用定量CT(QCT)探讨腹部脂肪及骨密度(BMD)随年龄变化的规律及腹内脂肪(VAT)与BMD的相关性。资料与方法选取行低剂量胸部CT联合QCT检查的健康体检者2442例,其中男1522例,女920例,根据年龄分为5个年龄段:30~39、40~49、50~59、60~69、70~90岁。采用QCT测量L2中心层面腹部总脂肪(TAT)、VAT、皮下脂肪(SAT)及腰椎BMD。分析不同性别各年龄段间TAT、VAT、SAT、BMD的差异及TAT、VAT、SAT与BMD的相关性。结果50岁以上男性各年龄段TAT、VAT高于30~39岁男性(P均<0.01),而SAT低于30~39岁男性(P均<0.05)。50岁以上女性各年龄段TAT、VAT、SAT高于30~39岁女性(P均<0.001)。50岁以上男性及女性各年龄段间TAT、VAT、SAT比较,差异均无统计学意义(P均>0.05),40~49、50~59岁年龄段分别较上一年龄段VAT明显增多(P均<0.01),BMD随年龄增长逐渐减低(P均<0.001)。多元逐步回归分析显示,VAT是女性BMD的独立影响因素(β=-0.089,P=0.007),TAT、SAT不是BMD的独立影响因素(P均>0.05)。结论腹部脂肪和BMD随年龄发生变化,男性和女性均在40~59岁出现VAT明显增多。VAT可能是女性BMD的独立负性影响因素。     

The relationship between bone mineral density and immobilization duration in hemiplegic limbs

OBJECTIVE: Prolonged immobilization in stroke is known to result in hypercalciuria, hypercalcemia, accelerated bone resorption, and osteoporosis. Furthermore, bone mineral loss accelerated with increasing duration of hemiplegia. Although stroke is a common disease that causes sudden immobilization, relatively few investigations of bone metabolism in stroke have been reported. The aim of this study was to investigate the changes in bone mineral density of the forearms and legs related to duration of hemiplegia-induced immobilization after stroke. METHODS: Forty-one hemiplegic patients with stroke were evaluated. The patients' age, gender and duration of hemiplegia-induced immobilization were recorded. The measurements of bone mineral density (BMD) in all patients were evaluated with DEXA using the Norland apparatus. The BMD values (g/cm2) were determined by measurements made in the lumbar vertebrae, both forearm and legs (femoral neck and trochanter). RESULTS: We found that bone mineral density was decreased in the affected extremities relative to the intact contralateral side on measurements by dual energy x-ray absorptiometry in bones such as forearm, femoral neck and trochanter. There was a significant difference between bone mineral density of paretic and nonparetic forearms and legs. Bone mineral density of the upper limbs was lower than that of the lower limbs. There was a negative correlation between duration of hemiplegia and BMD values. CONCLUSIONS: Bone mineral loss may be related to the duration of hemiplegia-induced immobilization. Bone mineral loss is accelerated when the duration of hemiplegia is prolonged.     

Bone marrow fat content in the elderly: a reversal of sex difference seen in younger subjects

Purpose:

To investigate vertebral bone marrow fat content in elderly subjects related to sex, age, and bone mineral density (BMD) and relate these findings to published data in younger subjects.

Materials and Methods:

A total of 259 healthy subjects (145 females, 114 males; age range, 62–90 years) underwent proton (¹H) MR spectroscopy of L3 vertebral body and BMD of the lumbar spine with results stratified according to age. Ninety age‐ and BMD‐matched subjects were selected to determine sex differences in marrow fat content and BMD.

Results:

In females, vertebral marrow fat content rose sharply between 55 and 65 years of age while in males vertebral marrow fat content rose gradually throughout life. Vertebral marrow fat content in females more than 60 years was approximately 10% higher in females than males, i.e., a reversal of sex difference reported in marrow fat content for subjects less than 60 years.

Conclusion:

Marrow fat content increases sharply in female subjects between 55 and 65 years of age while male subjects continue to increase marrow fat at a more gradual steady rate. Females older than 60 years have a higher marrow fat content than males. This increased deposition in marrow fat concurs with recognized changes in extraosseous fat distribution in postmenopausal females. J. Magn. Reson. Imaging 2012;36:225–230. © 2012 Wiley Periodicals, Inc.