Radionuclide methods for measuring the mineral content of bone tissue

All-Union Scientific Research Institute for Medical Instrument Engineering (VNIIMP), Moscow. Translated from Meditsinskaya Tekhnika, No. 2, pp. 12–14, March–April, 1992.     

Compton scatter densitometry in cancellous bone.

A single-source low-energy Compton densitometer has been used to investigate the effects of multiple scattering on density determinations. The relative electron density and mass density were determined in samples of known density, and in samples of human cancellous bone tissue. The influence of sample diameter on the measured relative electron density of known samples was investigated. The measured value was strongly dependent on the diameter and the density range of the sample. The bias inherent in the density determination which is attributable to multiple scattering and attenuation in human femoral bone was evaluated, and a correction for these effects is suggested for clinical measurements.     

Value of photon-absorption densitometry for the assessment of bone density

Senile osteroporosis itself is asymptomatic unless pain is induced by the static insufficiency of the skeleton, in long lasting disease. Conventional procedures for early diagnosis and control of patients are invasive and therefore not suitable for routine purposes. The efficiency of sodium fluoride for the treatment of senile osteoporosis after a minimum of 12 months has been established by invasive methods. It is the purpose of this study, to examine the value of photoabsorption-densitometry with double-isotope-method (125-J, 241-Am) for the evaluation of a therapeutic effect in this disorder. 7 patients with clinical and radiological evidence of senile osteoporosis (6 female, 1 male patient with ages of 56 to 87 years) underwent regular follow-up examinations for one year while on a regimen of 25mg. sodium fluoride, as retard, twice daily. The bone mineral content registered 1 cm. proximal of the proc. styloideus ulnaris (representative for the trabecular bone) and 8 cm proximal from the proc. styloideus ulnaris of the right forearm (representative for cortical bone) was not statistically different from the measurements registered prior to the study. However, the bone mineral content registered in both regions increased significantly, after 12 months treatment (p less than 0.05). This indicates that the assessment of bone mineral content by photonabsorptiondensitometry is a valuable method for therapeutic control of this disorder. The method is recommended as a routine procedure for the early diagnosis and for follow up of sodium fluoride therapy geriatric patients.     

Photon absorptiometry, bone densitometry and the challenge of osteoporosis

During the lifetime of Physics in Medicine and Biology, osteoporosis has been recognized as the cause of a major health burden for societies, particularly within developed countries. The health detriment is associated with the consequences of bone fractures and the subsequent increases in morbidity and mortality. Much of the credit for the current availability of means for identifying groups of subjects at risk of fracture and the provision of means for the effective treatment of excessive bone loss can be attributed to the technique of dual photon absorptiometry. In this review, the history of the development of techniques based on the interactions of x- and gamma-rays with bone is considered and the ultimate dominance of x-ray based absorptiometry is described. The advantages and disadvantages of current absorptiometric techniques are presented and the likely future path for bone measurement is outlined.     

High resolution bone mineral densitometry with a gamma camera

A technique is described by which the regional distribution of bone mineral can be determined in bone samples from small animals. The technique employs an Anger camera interfaced to a medical computer. High resolution (less than 1 mm) imaging is possible by producing magnified images of the bone samples. Regional densitometry of femurs from oophorectomised and bone grafted rats demonstrated significant heterogenity of bone mineral loss.     

Modern methods for diagnostic immunocytochemistry

Immunocytochemistry has become an important diagnostic tool. The reliability or otherwise of the technique depends upon attention to detail and the optimization of every step in what is sometimes a complex technical procedure. This article outlines basic theory and practice for the most commonly used procedures. It highlights the problems of endogenous biotin staining and avidin–biotin-based detection methods. Labelled polymer based methods are explained and compared with other commonly used detection methods. Recent advances in high-sensitivity methodology are discussed.     

The analysis of densitometry image of bone tissue based on computer simulation of X-ray radiation propagation through plate model

In this work, we have presented an attempt at the computer modelling of the attenuation effect of X-ray radiation which occurs in the densitometry test. The purpose of the modelling is to examine the extent to which the parameters of the plate model of bone tissue affect bone mineral density (BMD) parameter. In the modelling the fundamental functions realised by a densitometry device have been taken into consideration. Certain necessary assumptions simplifying the computation of the complex physical processes that occur during the transition of X-ray radiation through an object have been made. In order to compute the image produced by interaction of radiation the attenuation law is applied. The modelling of an object consists in defining its dimensions and its material characteristics. In the presented simulation the material characteristics of the object are limited to its attenuation coefficient. A different value of the coefficient can be defined for each voxel. The result image is produced by the calculation of partial attenuation in the individual voxels. The levels of grey in the image represent the value of the computed radiation intensity which is recorded in the "detector" after transition through the object. The simulation has been performed for the plate model representing trabecular bone tissue with 0.1mm porosity compartments. The results of the simulation of the plate model are presented. It can be observed that for certain modelled porosity compartments the size, structure and spatial arrangement are not properly recorded in the two-dimensional "detector". The recorded simulation results may be found useful for explaining difference that has been noticed between the BMD obtained from the densitometry test and the bone susceptibility to fracture.     

Morphological methods for estimation of the vitality of cartilage and bone tissue (author's transl)]

For estimation of the vitality of bone probes before transplantation it is possible to evidence the succinic dehydrogenase in native slides, which were made on a special microtome. For experience it is possible, too, to show the vitality of cartilage after injection of 35S (as Na-sulphate) with autoradiographic methods.     

骨密度测量与胸腰椎压缩骨折植入物治疗方式的选择

背景：经皮椎体后凸成形治疗中聚甲基丙烯酸甲酯附着在骨折断端,尽管起到了即刻固定骨折的作用,但也妨碍了纤维组织再生及新骨的形成,从长远角度来说是不利于非骨质疏松骨折愈合。 目的：分析骨密度测定对中老年胸腰椎压缩骨折手术方式及植入物选择的指导意义。 方法：选择单节段胸腰椎压缩骨折患者,根据腰椎L2~4骨密度值测定结果分为骨质疏松组和非骨质疏松组。骨质疏松组行球囊扩张椎体后凸成形治疗,非骨质疏松组行椎弓根钉置入复位内固定治疗。 结果与结论：骨质疏松组3例术中发生骨水泥椎旁渗漏,非骨质疏松组1例患者出现伤口感染。治疗后随访20~28个月,骨质疏松组2例发生邻近椎体骨折,非骨质疏松组内固定物取出后未出现椎体高度丢失、局部后凸角度增大等情况。骨质疏松组手术时间、出血量及术后3 d 目测类比疼痛评分低于非骨质疏松组(P < 0.05);两组椎体高度和局部后凸角较治疗前恢复显著(P < 0.05),非骨质疏松组较骨质疏松组更明显(P < 0.05)。表明经皮椎体后凸成形及椎弓根螺钉置入复位内固定均是中老年胸腰椎椎体压缩骨折的理想治疗方法,应根据患者骨质疏松程度采取针对性的治疗方法和植入物,疗效会更加显著。     

Correlation between ultrasound velocity and densitometry in fresh and demineralized cortical bone

OBJECTIVE:To compare ultrasound propagation velocity with densitometry in the diaphyseal compact cortical bone of whole sheep metatarsals.METHODS:The transverse ultrasound velocity and bone mineral density of 5-cm-long diaphyseal bone segments were first measured. The bone segments were then divided into four groups of 15 segments each and demineralized in an aqueous 0.5 N hydrochloric acid solution for 6, 12, 24 or 36 hours. All measurements were repeated after demineralization for each time duration and the values measured before and after demineralization were compared.RESULTS:Ultrasound velocity and bone mineral density decreased with demineralization time, and most differences in the pre- and post-demineralization values within each group and between groups were significant: A moderate correlation coefficient (r=0.75956) together with a moderate agreement was determined between both post-demineralization parameters, detected by the Bland-Altman method.CONCLUSION:We conclude that both ultrasound velocity and bone mineral density decrease as a result of demineralization, thus indicating that bone mineral content is of great importance for maintaining the acoustic parameters of cortical bone, as observed for cancellous bone. Ultrasound velocity can be used to evaluate both compact cortical bone quality and bone mineral density.     

Bioreactors for bone tissue engineering

Bone tissue engineering is a promising solution for patients with bone defects that require reconstruction. This regenerative therapy consists in culturing osteogenic cells on a biodegradable substrate to obtain a bio-hybrid construct that will stimulate bone healing after implantation. This multidisciplinary technology nevertheless requires further development before it can become routine clinical practice. One challenge is to achieve three-dimensional seeding and osteogenic commitment of mesenchymal stem cells on biomaterials under sterile and reproducible conditions. For this purpose, different dynamic culture systems have been developed. This paper reviews recent advances in the field of bioreactors for bone tissue engineering. The purpose of such systems is to improve nutrient delivery to the cells and generate shear stress that may promote cell differentiation into osteoblastic phenotypes. A brief overview of the value of computational fluid dynamics for understanding the cell environment is also provided. Finally, some proposals are made regarding the use of bioreactors as safe and controllable devices that will help commit cells and biomaterials for the regeneration of bone tissue.     

Collagen for bone tissue regeneration

In the last decades, increased knowledge about the organization, structure and properties of collagen (particularly concerning interactions between cells and collagen-based materials) has inspired scientists and engineers to design innovative collagen-based biomaterials and to develop novel tissue-engineering products. The design of resorbable collagen-based medical implants requires understanding the tissue/organ anatomy and biological function as well as the role of collagen's physicochemical properties and structure in tissue/organ regeneration. Bone is a complex tissue that plays a critical role in diverse metabolic processes mediated by calcium delivery as well as in hematopoiesis whilst maintaining skeleton strength. A wide variety of collagen-based scaffolds have been proposed for different tissue engineering applications. These scaffolds are designed to promote a biological response, such as cell interaction, and to work as artificial biomimetic extracellular matrices that guide tissue regeneration. This paper critically reviews the current understanding of the complex hierarchical structure and properties of native collagen molecules, and describes the scientific challenge of manufacturing collagen-based materials with suitable properties and shapes for specific biomedical applications, with special emphasis on bone tissue engineering. The analysis of the state of the art in the field reveals the presence of innovative techniques for scaffold and material manufacturing that are currently opening the way to the preparation of biomimetic substrates that modulate cell interaction for improved substitution, restoration, retention or enhancement of bone tissue function.     

Modern methods for diagnosis ofGardnerella infection

Comparison of morphological, bacteriological, serological, and genetic methods for diagnosis ofGardnerella infection in vaginosis showed that the first three methods are preferable, while the genetic method (polymerase chain reaction) is more efficient for identification ofGardnerella vaginalis in culture. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 130, No. 8, pp. 196–199, August, 2000     

Modern pathology methods for neural investigations

This session at the 2010 joint symposium of the Society of Toxicologic Pathology (STP) and the International Federation of Societies of Toxicologic Pathologists (IFSTP) explored modern neuropathology methods for assessing the neurotoxicologic potential of xenobiotics. Conventional techniques to optimally prepare and evaluate the central and peripheral neural tissues while minimizing artifact were reviewed, and optimal schemes were set forth for evaluation of the nervous system during both routine (i.e., general toxicity) studies and enhanced (i.e., specialized neurotoxicity) studies. Stereology was introduced as the most appropriate means of examining the possible impact of toxicants on neural cell numbers. A focused discussion on brain sampling took place among a panel of expert neuroscientists (anatomists and pathologists) and the audience regarding the proper balance between sufficient sampling and cost- and time-effectiveness of the analysis. No consensus was reached on section orientation (coronal sections of both sides vs. a parasagittal longitudinal section with several unilateral hemisections from the contralateral side), but most panelists favored sampling at least 8 sections (or approximately double to triple the current complement) in routine toxicity studies.     

Modern methods for diagnosis ofGardnerella infection

Comparison of morphological, bacteriological, serological, and genetic methods for diagnosis ofGardnerella infection in vaginosis showed that the first three methods are preferable, while the genetic method (polymerase chain reaction) is more efficient for identification ofGardnerella vaginalis in culture. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 8, pp. 196–199, August, 2000     

Comparison of radiographic texture analysis from computed radiography and bone densitometry systems

Osteoporosis is a disease that results in an increased risk of bone fracture due to a loss of bone mass and deterioration of bone structure. Bone mineral density (BMD) provides a measure of bone mass and is frequently measured by bone densitometry systems to diagnose osteoporosis. In addition, computerized radiographic texture analysis (RTA) is currently being investigated as a measure of bone structure and as an additional diagnostic predictor of osteoporosis. In this study, we assessed the ability of a peripheral bone densitometry (PD) system to yield images useful for RTA. The benefit of such a system is that it measures BMD by dual-energy x-ray absorptiometry and therefore provides high- and low-energy digital radiographic images. The bone densitometry system investigated was the GE/Lunar PIXI, which provides 512 x 512 digital images of the heel or forearm (0.2 mm pixels). We compared texture features of heel images obtained with this PD system to those obtained on a Fuji computed radiography (CR) system (0.1 mm pixels). Fourier and fractal-based texture features of images from 24 subjects who had both CR and BMD exams were calculated, and correlation between the two systems was analyzed. Fourier-based texture features characterize the magnitude, frequency content, and orientation of the trabecular bone pattern. Good correlation was found between the two modalities for the first moment (FMP) with r=0.71 (p value<0.0001) and for minimum FMP with r=0.52 (p value=0.008). Root-mean-square (RMS) did not correlate with r=0.31 (p value>0.05), while the standard deviation of the RMS did correlate with r=0.79 (p value<0.0001). Good correlation was also found between the two modalities for the fractal-based texture features with r=0.79 (p value<0.0001) for the global Minkowski dimension and r=0.63 (p value=0.0007) for the fractal dimension from a box counting method. The PD system therefore may have the potential for yielding heel images suitable for RTA.