Microradiography. I. Microradiography: a review.
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Microradiography↗
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Microradiography. II. Projection microradiography.
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Microradiography↗
Microradiography. III. A sealed-off x-ray tube for contact-microradiography.
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Fluoroscopy↗
Measurement of enamel demineralization using microradiography and confocal microscopy. A correlation study.
Substantial amounts of tooth minerals are lost during dental caries formation. Transversal microradiography, a well-accepted method used to quantify mineral loss, is a time-consuming technique which requires a thin enamel section (100 microns) and involves the use of x-rays. In an attempt to solve these difficulties, a procedure has been developed in which a human tooth specimen with demineralized enamel is cut in half (HT), stained with a fluorescent dye (rhodamine B) and analyzed using a laser scanning confocal microscope. A series of three studies was conducted to correlate measurements of enamel demineralization obtained from enamel thin (100 microns) sections (TS) using transversal microradiography with three parameters (area of the lesion; total and average dye fluorescence intensities) measured on the same TS or on a thicker section (HT) of the same specimen by laser scanning confocal microscopy. Results showed that a 0.1 mM rhodamine B solution provided the most adequate imaging conditions for confocal microscopy. Pearson's correlation coefficients, calculated between microradiography and confocal microscopy data obtained using a 0.1 mM rhodamine B solution, were: delta Z vs. HT lesion area = 0.95; delta Z vs. HT total fluorescence = 0.80; delta Z vs. HT average fluorescence = 0.74; delta Z vs. TS lesion area = 0.95; delta Z vs. TS total fluorescence = 0.74; delta Z vs. TS average fluorescence = 0.55. All these correlations coefficients were statistically significant (p < 0.01). It is concluded that in enamel demineralization studies statistically significant correlations exist between parameters measured using transversal microradiography and parameters quantified using confocal microscopy.
Analysis of Variance↗
High spatial resolution imaging of bone mineral using computed microtomography. Comparison with microradiography and undecalcified histologic sections.
RATIONALE AND OBJECTIVES: The application of various high-resolution (< 100 microns) imaging techniques for in vitro bone mineral analysis is explored. METHODS: The techniques of contact microradiography and microtomography, using the x-ray spectrum filtered out of synchrotron radiation (SR) and conventional staining techniques, are compared to each other by presenting a variety of different samples. The relationship between radiation exposure and spatial resolution micro-computed tomography (CT) images of a finger bone is explored. The relevant properties of SR are explained. RESULTS: In CT images, a spatial resolution of 100 microns was obtained. New bone mineral induced by mechanical periosteal irritation in a rabbit tibia was quantified. In one case a microradiogram and a microtomogram of the same slice were taken for comparison. Histologic sections and microradiograms taken from a specimen of a human femur for comparison are presented. CONCLUSIONS: Microradiography and staining techniques require rather sophisticated sample preparation; quantitative image analysis is more difficult as the resulting image must be digitized. The CT technique requires almost no sample preparation and allows for accurate bone mineral quantification. However, CT images with a resolution of several microns limit the sample size to a few mm. Micro-CT and microradiography can be performed with conventional x-ray sources, but the use of SR is of particular interest in high resolution imaging, because its white spectrum allows for optimum x-ray energy selection and its high intensity for short scan times.
Absorptiometry, Photon↗
Exercise-induced pulmonary haemorrhage in the horse: results of a detailed clinical, post mortem and imaging study. IV. Changes in the bronchial circulation demonstrated by C.T. scanning and microradiography.
The purpose of this study was to use radiographic contrast techniques and special imaging methods to identify and high-light bronchial arterial involvement in lung lesions associated with exercise-induced pulmonary haemorrhage (EIPH) in horses. The lungs from four horses with histories of EIPH were prepared for computerised tomographic scanning and microradiography by perfusing the broncho-oesophageal artery with a mixture of red latex and either barium or iodine contrast materials while the pulmonary supply received only blue latex. Computerised tomographic scan slices of the prepared inflated lungs were obtained from the caudal tip of the lung to the hilus. Microradiography of selected lung slices was also performed on a Faxitron. Diffuse areas of increased density, with preferential bronchial arterial supply noted on the computerised tomographic scans were confirmed by microradiography. Dense focal and diffuse plexuses of markedly hypertrophied and highly branched bronchial arterial networks were identified, centred around certain small airways. The vascular supply to these plexuses was recruited predominantly from neighbouring bronchial vessels, and in some cases, from the enlarged vasa vasorum of pulmonary arteries sending anastomoses to the affected areas. The authors conclude that bronchial vascular lesions in EIPH cases are the likely origin of haemorrhage; that small airway disease is the probable initiating stimulus for bronchial vascular proliferation in these lesions; and that the morphology and nature of the neovascular tissue in these lesions provides the conditions leading to haemorrhage in the lungs of horses with EIPH.
Animals↗
Wavelength-independent microradiography: a method for non-destructive quantification of enamel and dentin mineral concentrations using polychromatic x-rays.
Wavelength-independent Microradiography (WIM), described in this paper, used polychromatic, high-energy (less than or equal to 60 kV) x-rays for determination of mineral concentrations in tooth material non-destructively. This was done with the aid of a reference step-wedge made of 94% aluminum, 6% zinc. The mass attenuation coefficient of this material has a wavelength-independent ratio to the mass attenuation coefficients of enamel and dentin. With this method, mineral concentrations of enamel and dentin samples, with a thickness up to 500 microns, were determined at 20- and at 60-kV tube voltage. The samples were demineralized for 72 and 144 h and measured again. Comparison of the data showed that mineral quantification was within 1.5%, independent of the x-rays used. Finally, these mineral concentrations--obtained from the Wavelength-independent Microradiography--were compared with measurements of the same samples by Longitudinal Microradiography. A correlation of 0.99 was found for enamel and one of 0.96 for dentin.
Dental Enamel↗
Wavelength-independent microradiography used for quantification of mineral changes in thin enamel and dentin samples with natural surfaces, pseudo-thick tooth sections, and whole teeth.
Tests of the efficacy of therapeutic agents for caries repair or prevention in vitro or in situ should be performed as realistically as possible. This implies the non-destructive assessment of mineral changes in whole teeth. In this study, Wavelength-independent Microradiography (WIM), a non-destructive form of microradiography that uses polychromatic x-rays, was tested for its use in following mineral changes during demineralization of whole teeth. Since the method was, in a previous paper, only tested on flat samples of about 0.3 mm in thickness, the present study aimed to adapt and test WIM for use on thicker samples. This was done in three steps: In the first step, natural surfaces were introduced. The mineral content of enamel and dentin samples about 0.3 mm in thickness and with natural (curved) surfaces was determined by WIM, and the result was compared with mineral measurements performed with Longitudinal Microradiography (LMR). A correlation of 0.98 was found for both the enamel and the dentin samples. In the second step, the thickness of whole teeth was added. Thick tooth sections were simulated by addition of a 5-mm block of dentin to such thin enamel and dentin samples. Mineral measurements with WIM of the samples plus the dentin block were compared with mineral measurements of the thin samples (without block). A correlation of 0.97 was found for enamel, and one of 0.90 was found for dentin. Finally, in a third step, the demineralization of whole premolars was followed as a function of time.
Dental Caries↗
Microradiography with an x-ray image magnifier: application to dental hard tissue.
The superior spatial resolution obtained with parallel-beam microradiography over conventional contact microradiography has allowed us to image microstructural features of dental hard tissue not previously reported. Our efforts to extend these techniques to provide a real-time capability for viewing in situ demineralization and remineralization effects, at and below the 1-micron level, have resulted in an instrument with several novel and unique features. Using a synchrotron radiation source of x rays and diffraction image magnification, we are now able to change magnification at will (x-ray zoom lens). In addition, the energy range over which the instrument operates gives one considerable flexibility in optimizing image contrast. The techniques of parallel-beam microradiography, and diffraction image magnification are applicable to problems in many other areas of science. Using examples within dental research, the uniqueness and versatility of these new techniques are discussed.
Dental Enamel↗
Some pathological features of ankylosing spondylitis as revealed by microradiography and tetracycline labelling.
Five spine specimens obtained at autopsy and five biopsies of sacroiliac joints from subjects with ankylosing spondylitis were submitted to microradiography and to fluorescence microscopy for detection of tetracycline. Decalcified histological sections were also prepared. Microradiography provides a link between the clinical X-ray picture and the classical decalcified section; it enables calcified cartilage, and hence the early stage of most syndesmophytes to be recognised more easily and accurately; It revealed a peculiar calcification of elastic fibers of the ligamentum flavum. Tetracycline labels showed that: in an early case of sacro-iliac arthritis, calcification of the articular cartilage might partly explain the desification of the X-ray picture; syndesmophytes were thickening at both their superficial and deep faces; thickening, lengthening and internal remodelling of the intervertebral bridges occurred together; and calcium was deposited at the end-plates as well.
Adult↗
Evidence for negative correlation between quantitative histological studies and microradiography of iliac crest bone and forearm osteodensitometry in elderly women with osteoporosis.
Quantitative histomorphometric and microradiographic analysis of iliac crest bone biopsy specimens of 10 unselected and untreated postmenopausal women with osteoporosis was performed and the results were correlated with the values measured by osteodensitometry on the right forearm. No positive correlation between histomorphometry or microradiography and osteodensitometry was observed. Moreover, the data of various histomorphometric parameters and those of the bone mineral content measured by microradiography revealed a significant negative correlation when compared to the values obtained by osteodensitometry. Our results suggest, that evaluation of one skeletal site is not necessarily representative of the entire skeleton in patients with postmenopausal osteoporosis.
Aged↗
Microradiography to evaluate bone growth into a rat mandibular defect.
Microradiography has been evaluated to measure bone healing into a 5.0mm outer diameter mandibular defect in the rat. This method provides high-resolution radiographs of the defects that can be used for an accurate measurement of bone defect healing. In 12 rats, the defect widths of 42-day-old mandibular defects have been measured both using microradiographs and histological sections. The defect width+/-S.D. measured 3.42+/-0.98 mm microradiographically and 3.47+/-1.11 mm histologically. Both methods were accurate in determining defect widths but microradiography has the advantage over histology that an image is obtained from the entire defect, making it possible to measure areas of bone growth.
Animals↗
Mineral distribution in the enamel of teeth with amelogenesis imperfecta as determined by quantitative microradiography.
The aim of the present investigation was to determine the mineral distribution in the enamel of teeth with amelogenesis imperfecta (AI) by quantitative microradiography. A further aim was to correlate the findings to clinical manifestations and inheritance patterns for AI. Included in the study were a total of 29 teeth with AI, 28 primary and one permanent, and seven unaffected teeth, five primary and two permanent. Quantitative microradiography was applied to sagittally ground sections, 70-90 microns, of the teeth. The mineral content of the enamel, expressed as percentage by volume, was lower in most of the teeth with AI than in the unaffected teeth. The largest range for the mineral distribution was found in the enamel of the variants clinically characterized by hypomineralization. These teeth showed a mineral distribution pattern that reflected an extremely low mineral content in the bulk of the enamel. In the AI teeth clinically characterized by hypoplasia, the mineral distribution pattern was similar to that of the unaffected teeth, although with larger local variations in mineral content. Apart from the teeth connected with X-linked inheritance, no differences were found among teeth with similar clinical variants connected with different inheritance patterns.
Amelogenesis Imperfecta↗
Microradiography of experimental root surface caries in man.
The aim of this study was to describe the pattern and rate of mineral loss during experimental root surface caries in situ without giving frequent sucrose rinses as a supplementary cariogenic challenge. Six elderly persons carried at total of 18 specimens of unerupted human root surface in recessions of lower partial dentures for 1, 2 and 3 months. Another six root surfaces served as controls. No cleaning of the specimens was allowed during the experimental period whereas the natural dentition was cleaned with a nonfluoride toothpaste. All the specimens, as observed by quantitative microradiography, exhibited subsurface caries lesions. Despite variation between individuals the depth of subsurface demineralization increased linearly with time, the average depth of the lesions being 240 microns after 1 month and 630 microns after 3 months. Delta MC, calculated as the difference in total mineral content between control and test specimens throughout the lesions, increased linearly with time from 2,000 to 8,400 vol% microns after 1 and 3 months, respectively. Preparation for microradiography induced a certain shrinkage of the lesions which resulted in an underestimation of the actual loss of mineral. It is concluded that this experimental model is suitable for studying the etiology and prevention of root surface caries provided the interindividual variation is taken into account.
Aged↗
Shrinkage prevention of in vitro demineralized human dentine in transversal microradiography.
The shrinkage of demineralized dentine is a serious problem in the assessment of mineral distributions and mineral changes by means of microradiography. In this article it is shown that a treatment with ethanediol of the thin slices used for transversal microradiography prevents shrinkage for about 1 h. Without this so-called diol treatment, the shrinkage effects in demineralized dentin are about 20% in lesion depth and about 30% in mineral loss (delta Z) after 120-second drying in air. The prevention of shrinkage by diol treatment of dentine lesions is not influenced by the presence of a surface layer.
Dentin↗
Contact microradiography of dentine under wet conditions to prevent lesion shrinkage.
A considerable shrinkage of dentinal lesions is the result of desiccation of dentine sections during contact microradiography. We introduce a simple modification which allows the dentine to be wet during the microradiographic procedure. The volume stability of both sound and demineralized dentine sections microradiographed under wet conditions is compared to sections microradiographed while being exposed to the air. Under wet conditions no shrinkage could be detected of both sound and demineralized sections. Within 15 min exposure to the air, demineralized sections showed their lesion depth to be significantly reduced by 21%, resulting in an underestimation of the mineral loss of 44%. No shrinkage was observed in the air-dried sound dentine. Especially when high-resolution plates are used, which require an extended exposure time, microradiography of dentine sections under wet conditions is recommended. In longitudinal de- and remineralization studies, the use of water instead of impregnation with low-volatility liquids is to be preferred because of the possible effects of these liquids on the mineralization processes.
Absorptiometry, Photon↗
Major topics in quantitative microradiography of enamel and dentin: R parameter, mineral distribution visualization, and hyper-remineralization.
Three aspects of quantitative transverse microradiography are described and discussed: (1) the average mineral loss parameter of enamel or dentin lesions (R) in vol%; (2) mineral distribution visualization of lesions by means of a computer-assisted videodensitometric (CAV) method; and (3) the microradiography of hyper-remineralized lesions. "R", defined as the average amount of mineral lost (or gained) in a lesion per unit lesion length, is a useful parameter in dental caries. The results show that, in vitro, R is about constant over the demineralization period for enamel and dentin. This was found even for quite different dissolution kinetics. R is strongly reduced by the presence of small amounts of fluoride in the demineralizing system. R of dentin lesions is smaller than for enamel lesions. We conclude that the mineral loss value (delta Z) and the lesion depth (ld) are in general dependent parameters during in vitro or in situ studies on enamel or dentin. During lesion formation, mineral loss from the lesion and acid penetration in the tissue are obviously linked. This is possible only if the mineral content in the lesion does not change very much after passage of the lesion front. The CAV method presented is illustrated for enamel lesions formed in vitro and in situ.
Absorptiometry, Photon↗
Application of transverse microradiography for measurement of mineral loss by acid erosion.
This paper describes a novel application of transverse microradiography for the detection and quantification of mineral loss due to acid erosion in thin tooth sections. Sixty-four specimens were randomly divided into eight equal-sized groups and exposed to an orthophosphoric-acid-based erosive fluid (pH = 3) for 0, 0.25, 0.5, 1, 2, 5, 12, or 24 hrs. We made microdensitometric scans separately across both enamel and dentin to derive data for the total mineral loss and the minimum mineral content within the eroded area. We then analyzed specimens using a profilometer to determine (1) the area above a plot of penetration depth against distance and (2) the maximum depth of penetration. Correlation coefficients for comparisons between microradiographic and profilometric data for both enamel and dentin specimens varied between 0.87 and 0.96. Two-sample t tests demonstrated that the microradiographic technique could detect early erosion, i.e., discriminate between erosion times of less than 1 hr. It was concluded that this application of transverse microradiography was a useful and acceptable method for the measurement of early mineral loss in vitro, occurring as a result of acid erosion.
Absorptiometry, Photon↗