Bone densitometry and the diagnosis of osteoporosis

Parameter estimation-based discrimination method for osteoporosis stage with ultrasound bone densitometer

This paper proposes a new method for predicting the stage of osteoporosis by estimating bone-density parameters using an ultrasonic-bone densitometer. Using the developed ultrasonic bone densitometer, the ultrasonic signal passing through the phalanx of the finger was measured, and the measured signal was preprocessed to generate input data for parameter estimation. The Nakagami probability-density function was used for modeling this data, and optimal bone-density parameters were estimated using an optimization problem - to predict the stage of osteoporosis. The proposed method was verified through in vitro and in vivo experiments. In phantom experiments, cubes with different materials (ABS plastic, PLA plastic, Nylon) were used, and each cube had a different density through internal density so that it could mimic bones. The experiments were conducted using them and the results were compared. The experimental results confirmed that there was a correlation between the density and estimated parameters for all three materials. In the in vivo experiment, the osteoporosis stages were classified as normal, osteopenia, and osteoporosis, and the bone-density parameters were estimated for the participants of each group. Thus, a basis for predicting the stage of osteoporosis was created, and data from new participants were collected and verified as test data. As a result, normal and abnormal groups (osteopenia and osteoporosis) were predicted.

Changes in distribution of bone densitometry equipment from 1996 to 2006 in Japan

Many types of bone densitometry equipment are available in Japan, but the numbers of such machines and the numbers of institutions that offer bone densitometry have not been clarified. We analyzed the data from annual surveys conducted by the Japan Osteoporosis Foundation from 1996 to 2006, and we obtained the following results on the use of densitometry equipment: (1) In 1996 there were 6,687 units of bone densitometry equipment in 6,483 institutions in Japan; in 2006 there were 16,371 units in 15,020 institutions. (2) In 2006, of the types of institutions with bone densitometry equipment, the number of clinics was the highest, followed in order by general hospitals, other types of institutions, screening institutions and university hospitals. Rates of increase in the installation of equipment in clinics and other types of institutions were high during the 11-year period from 1996. (3) From 1996 to 2006 the region of interest most frequently used for bone densitometry was the radius. However, during the 11-year period, the proportion of radial densitometry equipment in all institutions with bone densitometry equipment decreased, whereas the proportion of calcaneal densitometry equipment increased. (4) The number of dual-energy X-ray absorptiometry (DXA) units was the highest from 1996 to 2006. However, the proportion of DXA machines in all institutions with bone densitometry equipment decreased over the 11-year period, whereas the proportion of quantitative ultrasound (QUS) machines increased. (5) In 2006, bone densitometry equipment was available in 118 institutions per million Japanese people. Central DXA (spine/hip) equipment was available in 15 per million, radial DXA equipment in 63 per million, and calcaneal QUS equipment in 44 per million. (6) In 2006, among those places with bone densitometry equipment, 46% of university hospitals, 14% of general hospitals, 12% of screening institutions, 5% of clinics, and 6% of other types of institutions possessed more than one type of densitometry equipment. (7) In 2006, central DXA (spine/hip) was frequently available in university hospitals, radial densitometry equipment in general hospitals and clinics, and calcaneal densitometry equipment in screening institutions and other types of institutions.

Analysis of bone mineral density and bone turnover in the presence of polymethylmethacrylate particles

Polymethylmethacrylate (PMMA) particles generated from joint arthroplasties appear to contribute to aseptic implant loosening through inflammation-induced periprosthetic osteolysis. However, osteolysis appears to be multifactorial; whether a direct link exists between PMMA particles and osteolysis in vivo is unproven. With the aim to define the relationship between PMMA particles and osteolysis, the authors analyzed the bone mineral density, using microCT scans preoperatively, the first day postoperatively and then every 7-10 days for 32 days, and bone turnover, using (18)F-fluoride positron emission tomography scanner (PET scan) at 8 weeks in four groups of mice that had undergone intramedullary femoral injection. The experimental group of five mice was injected with PMMA particles, and compared with two negative control groups (no injection and injection with the carrier, phosphate-buffered saline) and one positive control group (injection of PMMA particles contaminated with endotoxin). There was no significant change in bone mineral density with addition of PMMA particles, and no evidence of osteolysis. However, bone turnover was increased in the presence of PMMA particles. Even though a direct link between PMMA particles and osteolysis was not found in the short term, PMMA particles appear to influence the regenerative capacity of bone.

The effectiveness of bone mineral density as supplementary tool for evaluation of the osteogenic potential in patients with spinal fusion

Study Design

Retrospective study.

Purpose

This study was designed to determine the effectiveness of bone mineral density measurement as a supplementary tool for evaluation of osteogenic potential in patients with spinal fusion. To this end, we correlated bone mineral density (BMD) with osteogenic potential from cultured mesenchymal stem cells (MSCs).

Overview of Literature

Many studies have correlated osteogenic potential of in vitro cultured MSCs with aging or osteoporosis.

Methods

We studied twenty-five individuals with harvested bone marrow from the ilium during lumbar spinal surgery. The BMD of the femoral neck was measured using dual energy X-ray absorptiometry prior to bone marrow aspiration, and the osteoporotic group was classified as those with T-scores below-2.5. After MSCs were isolated from bone marrow, in vitro induction of osteogenesis was performed. We analyzed the patient's osteogenic potential from cultured MSCs such as mineral deposition stain, bone alkaline phosphatase (ALP) activity and osteoblast-specific gene expression in RT-PCR.

Results

On mineral staining, the osteoporotic group had a scanty matrix mineral deposition in contrast to the non-osteoporotic group. The expression of osteocalcin in the osteoporotic group was 1.5 to 3 times less than in the non-osteoporotic group. At the 3^rd week after the induction of osteogenesis, the activity of ALP of cultured MSCs in the osteoporotic group was lower than in the control group (mean, 45±19 u/L, in osteoporotic group vs 136±7 u/L in non-osteoporotic), and there was a statistically significant and positive correlation between BMD & ALP (r=0.487, p=0.013).

Conclusions

There is a positive correlation between BMD and osteogenic potential derived from MSCs. The measurement of BMD can provide supplementary data for evaluating osteogenic potential clinically.

[Predictive value of ultra-sound densitometry as a method of selective screening for osteoporosis in primary care]

OBJECTIVE

To determine the cut-off point of calcaneous quantitative ultrasound densitometry (QUS) as a selection method in primary care for referral of postmenopausal women for dual energy x-ray absorptiometry (DXA).

DESIGN

Diagnostic techniques trial.

SETTING

Four general practices in the Basque Country Autonomous Region, Spain.

PARTICIPANTS

Randomly selected Caucasian women older than 45, chosen at random. A sample size of 146 women was used.

INTERVENTIONS

Calcaneous ultrasound bone mineral density (BMD) measurement, using Achilles Express(R) and DXA.

PRINCIPAL MEASUREMENTS

T-score BMD measurement on both devices. The sensitivity, specificity and positive predictive values of QUS and finally the ideal cut-off value were calculated.

RESULTS

The mean age of the sample was 58.2 (17.7) (range, 48-83 years old). The prevalence of women with osteoporosis, osteopaenia and normal DXA was 14.1%, 50.4% and 35.5%, respectively. The estimated sensitivity of QUS was 78.9% (56.7-91.5) and the specificity was 64.7% (55.6-72.8). The negative predictive value (NPV) was 94.9% (87.7-98.0) and the positive predictive value (PPV) was 26.8% (17.0-39.6). After the COR curve analysis, the ideal cut-off for QUS was determined as a T-score </= -2.0.

CONCLUSIONS

Given its high NPV, QUS can be considered a useful device for screening before DXA. Its low PPV means it has to be combined with other complementary or substitutive selective screening methods, such as predictive rules, which should be evaluated in each specific use.

Mechanical alterations of rabbit Achilles' tendon after immobilization correlate with bone mineral density but not with magnetic resonance or ultrasound imaging

OBJECTIVE

To assess the usefulness of magnetic resonance imaging (MRI), ultrasound (US) imaging, or bone mineral density (BMD) in predicting the mechanical properties of immobilized rabbit Achilles' tendons.

DESIGN

Experimental study.

SETTING

Basic university laboratory.

ANIMALS

Twenty-eight rabbits.

INTERVENTIONS

Twelve rabbits had 1 hindlimb casted for 4 weeks and 10 rabbits were casted for 8 weeks. Contralateral legs and 12 normal hindlimbs served as controls.

MAIN OUTCOME MEASURES

Achilles' tendon dimensions on MRI and US, T1- and T2-signal intensities on MRI, classification of abnormalities on MRI and US; BMD of the calcaneus with dual-energy x-ray absorptiometry. Biomechanic measures consisted of peak load, stiffness, and stress. Imaging variables were correlated with biomechanic alterations.

RESULTS

Immobilized Achilles' tendons were weaker and showed decreased mechanical stress compared with their contralateral legs and controls (all P<.05). MRI and US revealed larger Achilles' tendons after immobilization. However, neither increased MRI nor US signal abnormality was found. BMD was lower in immobilized calcanei and larger in contralateral legs than controls. Only BMD correlated with both the decreased peak load (R2=.42, P<.05) and stress (R2=.54, P<.05) of immobilized Achilles' tendon.

CONCLUSIONS

This study established weakened mechanical properties of immobilized Achilles' tendons. BMD of the calcaneus, but not MRI and US, was predictive of the mechanical alterations in immobilized Achilles' tendons. BMD may be a useful biomarker to monitor disease and recovery in Achilles' tendons.

A comparison of bone mineral density in the spine, hip and jaws of edentulous subjects

OBJECTIVES

The aim was to investigate the relationship between bone mineral density (BMD) of the jaws (mandible and maxilla) and other skeletal sites. In addition, the influence of gender, smoking and the number of years without natural teeth were examined.

MATERIALS AND METHODS

18 edentulous patients (9 females, 9 males) with a mean age of 67.1 (sd 12.6) years had DXA scans to assess the BMD of the lumbar spine and hip, together with the ramus, body and symphysis of the mandible and the anterior of the maxilla.

RESULTS

BMD values for the ramus were similar to those for the femur but significantly lower than the lumbar spine. The body and anterior mandible had higher values and the anterior maxilla lower values than both the femur and ramus. The ramus BMD showed moderately strong relationships with the standard measures of BMD in the spine and hip, but the BMD of other areas of the jaws showed no relationship with skeletal sites. The BMD for both the hip and the ramus showed an inverse relationship with increasing age. There was no statistically significant relationship between BMD of hip, spine and jaw and either years edentulous or cigarette years. (207)

CONCLUSIONS

Although the ramus of the mandible may show correlation of BMD with skeletal sites, the areas of the jaws where implants may be placed do not. Therefore BMD of the skeletal sites could not be used to predict BMD of the jaws. The BMD of the jaws as measured by DXA showed no relationship with either years edentulous or cigarette smoking.

Monitoring bone mass, bone density and bone geometry in children and adolescents

The number of articles dealing with pediatric bone mass measurements has flourished during the last decade. The reasons include the awareness that bone gained early in life is an important factor in determining the risk of osteoporosis later in life and the expanding number of pediatric diseases associated with low bone mass. Dual-energy x-ray absorptiometry is the most common method for measurement of bone mineral content or bone mineral density. Quantitative computed tomography and quantitative ultrasound are the emerging techniques which offer the possibility of measuring bone mineral content, bone mineral density and quantitative ultrasound parameters that are unique to children and will be discussed in this review. The interpretation of bone mass measurements is also often difficult in growing individuals and the peculiar aspects pertaining to this problem are examined.

Thawing of frozen calcaneus bone specimens has no effect on the bone mineral density using dual energy x-ray absorptiometry: a study in rabbits and humans

The purpose of this paper is to study whether the deep freezing of bone and later thawing affects the bone mineral density (BMD) measurement. We used 56 calcanei from 28 adult female New Zealand white rabbits and 102 human calcanei from 51 donors post-mortem (27 men and 24 women, age 30-89). Dual energy x-ray absorptiometry evaluated BMD of the frozen specimen and of the thawed specimen. A main analysis compared BMD of each specimen in the frozen and thawed states. The mean BMD of 224 areas of frozen rabbits' calcanei was 0.31 +/- 0.08 g cm(-2) (95% confidence interval (CI) from 0.30 to 0.32 g cm(-2)) while the mean BMD of thawed rabbits' calcanei was 0.31 +/- 0.08 g cm(-2) (95% CI from 0.30 to 0.32 g cm(-2); paired t-test p > 0.01). The mean BMD of 306 areas of frozen human calcaneus was 0.73 +/- 0.22 g cm(-2) (95% CI from 0.70 to 0.76 g cm(-2)) while the mean BMD of thawed human calcaneus was 0.73 +/- 0.22 g cm(-2) (95% CI from 0.70 to 0.76 g cm(-2); p > 0.01). For both the rabbit and the human calcanei, a Bland-Altman analysis showed a mean difference between the BMD in the frozen and thawed states of 0.00 (limits of agreement, rabbit: -0.07 to 0.08 g cm(-2), human: -0.16 to 0.21 g cm(-2)). A high correlation was observed between calcaneus BMD in the frozen and thawed states (r = 0.94, 0.97, 0.92 and 0.99 respectively in all rabbit calcanei, all human calcanei, immobilized rabbit calcanei and osteopenic human calcanei, all p < 0.01). Bone mineral density is not affected by deep freezing and later thawing of the specimen. Therefore, the specimens need not be thawed to obtain valid and precise BMD measurement. These results are relevant to general musculoskeletal as well as osteoporosis research where the specimens undergo multiple tests in series.

Bone mineral density among premenopausal women with early breast cancer in a randomized trial of adjuvant endocrine therapy

PURPOSE

To examine the effects on bone mineral density of 2 years of treatment with a luteinizing hormone-releasing hormone (LHRH) agonist alone or in combination with tamoxifen or tamoxifen alone in premenopausal breast cancer.

PATIENTS AND METHODS

We recruited 89 women from two centers in Stockholm participating in a randomized multicenter trial of three different endocrine approaches in the adjuvant setting (Zoladex in Premenopausal Patients Trial). The women were assigned to receive the LHRH agonist goserelin with or without tamoxifen, tamoxifen alone, or no endocrine therapy. The treatment was given for 2 years. We measured total-body bone density before start of treatment and at 12, 24, and 36 months.

RESULTS

After 2 years of treatment, there was a significant loss of bone mineral density (mean change, -5%; P <.001) in the women receiving goserelin alone. The combined goserelin and tamoxifen treatment, as well as tamoxifen alone, resulted in a lesser but statistically significant decline in bone mineral density (mean change, -1.4%; P =.02; and -1.5%; P <.001). One year after cessation of treatment, the goserelin group alone showed a partial recovery from bone loss (mean change, 1.5%; P =.02).

CONCLUSION

Two years of ovarian ablation from goserelin treatment caused a significant reduction in bone mineral density but there was a partial recovery from the bone loss 1 year after cessation of treatment. The addition of tamoxifen seems to partially counteract the demineralizing effects of goserelin.

Reproducibility of bone mineral density measurement in daily practice

BACKGROUND

Bone mineral density (BMD) measurements are frequently performed repeatedly for each patient. Subsequent BMD measurements allow reproducibility to be assessed.

OBJECTIVE

To examine the reproducibility of BMD by dual energy x ray absorptiometry (DXA) and to investigate the practical value of different measures of reproducibility in a group of postmenopausal women.

METHODS

Ninety five women, mean age 59.9 years, underwent two subsequent BMD measurements of spine and hip. Reproducibility was expressed as smallest detectable difference (SDD), coefficient of variation (CV), and intraclass correlation coefficient (ICC). Sources of variation were investigated by multilevel analysis.

RESULTS

The median interval between measurements was 0 days (range 0-45). The mean difference (SD) between the measurements (g/cm(2)) was -0.001 (0.02) and -0.0004 (0.02) at L1-4 and the total hip, respectively. At L1-4 and the total hip, SDD (g/cm(2)) was +/-0.05 and +/-0.04 and CV (%) was 1.92 and 1.59, respectively. The ICC at spine and hip was 0.99.

CONCLUSIONS

Reproducibility in the postmenopausal women studied was good. In a repeated DXA scan a BMD change exceeding 2 radical 2CV (%), the least significant change (LSC), or the SDD should be regarded as significant. Use of the SDD is preferable to use of the CV and LSC (%) because of its independence from BMD and its expression in absolute units. Expressed as SDD, a BMD change of at least +/-0.05 g/cm(2) at L1-4 and +/-0.04 g/cm(2) at the total hip should be considered significant.

Breast imaging flow models

Economically efficient and clinically effective breast imaging can be achieved through combinations and permutations of four fundamental breast imaging flow models: (1) the traditional flow model, (2) the online flow model, (3) the women's imaging flow model, and (4) the combination-care flow model. The structure, strengths, and weaknesses of these four individual breast imaging flow models are described and compared.

Establishment of peak bone mass

Among the main areas of progress in osteoporosis research during the last decade or so are the general recognition that this condition, which is the cause of so much pain in the elderly population, has its antecedents in childhood and the identification of the structural basis accounting for much of the differences in bone strength among humans. Nevertheless, current understanding of the bone mineral accrual process is far from complete. The search for genes that regulate bone mass acquisition is ongoing, and current results are not sufficient to identify subjects at risk. However, there is solid evidence that BMD measurements can be helpful for the selection of subjects that presumably would benefit from preventive interventions. The questions regarding the type of preventive interventions, their magnitude, and duration remain unanswered. Carefully designed controlled trials are needed. Nevertheless, previous experience indicates that weight-bearing activity and possibly calcium supplements are beneficial if they are begun during childhood and preferably before the onset of puberty. Modification of unhealthy lifestyles and increments in exercise or calcium assumption are logical interventions that should be implemented to improve bone mass gains in all children and adolescents who are at risk of failing to achieve an optimal peak bone mass.

Peripheral or central densitometry: does it matter which technique we use?

Over the past decade, bone density scans have assumed an essential role in the diagnosis of osteoporosis. Although dual X-ray absorptiometry (DXA) scans of the central skeleton remain widely used, a variety of different types of equipment for measuring peripheral sites is now available. However, the poor correlation between different types of measurement and a lack of consensus on how results from peripheral sites should be interpreted have proved a barrier to the more widespread use of these devices. These issues prompt the following questions: Which technique best identifies patients at risk of fracture? What approaches to scan interpretation ensure the closest agreement among different methods? Does it matter if different patients are selected for treatment on the basis of different techniques? The relative risk (RR)of fracture derived from prospective studies is a key parameter for comparing the clinical value of different techniques. Recent reports confirm the advantages of hip bone mineral density compared with peripheral measurements for predicting hip fracture risk, although for fractures at other sites the differences are inconclusive. Using receiver operating characteristic curves, we show that the guidelines adopted for scan interpretation are of crucial importance for ensuring that the information provided is used effectively. The closest agreement among different techniques is achieved by setting thresholds for peripheral devices that target either the same percentage of the population or the same percentage of future fracture cases as femur DXA. Different methods select different groups of individuals from the total pool of patients who will later sustain a fracture, with the most successful technique being the one with the largest RR value. The emphasis placed by many studies on validating new techniques by studying their correlation with DXA may lead to the clinical value of peripheral devices being underestimated when the key datum is the RR value inferred from prospective fracture studies.