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[en] Purpose: To develop directional fractal signature methods for the analysis of trabecular bone (TB) texture in hand radiographs. Problems associated with the small size of hand bones and the orientation of fingers were addressed. Methods: An augmented variance orientation transform (AVOT) and a quadrant rotating grid (QRG) methods were developed. The methods calculate fractal signatures (FSs) in different directions. Unlike other methods they have the search region adjusted according to the size of bone region of interest (ROI) to be analyzed and they produce FSs defined with respect to any chosen reference direction, i.e., they work for arbitrary orientation of fingers. Five parameters at scales ranging from 2 to 14 pixels (depending on image size and method) were derived from rose plots of Hurst coefficients, i.e., FS in dominating roughness (FSSta), vertical (FSV) and horizontal (FSH) directions, aspect ratio (StrS), and direction signatures (StdS), respectively. The accuracy in measuring surface roughness and isotropy/anisotropy was evaluated using 3600 isotropic and 800 anisotropic fractal surface images of sizes between 20 × 20 and 64 × 64 pixels. The isotropic surfaces had FDs ranging from 2.1 to 2.9 in steps of 0.1, and the anisotropic surfaces had two dominating directions of 30° and 120°. The methods were used to find differences in hand TB textures between 20 matched pairs of subjects with (cases: approximate Kellgren-Lawrence (KL) grade ≥2) and without (controls: approximate KL grade <2) radiographic hand osteoarthritis (OA). The OA Initiative public database was used and 20 × 20 pixel bone ROIs were selected on 5th distal and middle phalanges. The performance of the AVOT and QRG methods was compared against a variance orientation transform (VOT) method developed earlier [M. Wolski, P. Podsiadlo, and G. W. Stachowiak, “Directional fractal signature analysis of trabecular bone: evaluation of different methods to detect early osteoarthritis in knee radiographs,” Proc. Inst. Mech. Eng., Part H 223, 211–236 (2009)]. Results: The AVOT method correctly quantified the isotropic and anisotropic surfaces for all image sizes and scales. Values of FSSta were significantly different (P < 0.05) between the isotropic surfaces. Using the VOT and QRG methods no differences were found at large scales for the isotropic surfaces that are smaller than 64 × 64 and 48 × 48 pixels, respectively, and at some scales for the anisotropic surfaces with size 48 × 48 pixels. Compared to controls, using the AVOT and QRG methods the authors found that OA TB textures were less rough (P < 0.05) in the dominating and horizontal directions (i.e., lower FSSta and FSH), rougher in the vertical direction (i.e., higher FSV) and less anisotropic (i.e., higher StrS) than controls. No differences were found using the VOT method. Conclusions: The AVOT method is well suited for the analysis of bone texture in hand radiographs and it could be potentially useful for early detection and prediction of hand OA
[en] The author studied the effect of periapical bone loss on radiographic interpretation by using a dry adult human mandible. Artificial bone lesions were created at the apices of two mandibular second molars and four mandibular bicuspids. The jaw was stabilized and various artificial lesions were radiographed under ideal circumstances. Radiographic pictures were recorded and compared with the size of the actual lesions. The obtained results were as follows: 1. The size of actual lesions were always larger than their radiographic pictures. 2. The size of actual lesion had a greater discrepancy in the molar area where the cortical plates were thick, but the lesions in the bicuspid areas were slightly larger than their radiographic pictures, and in these areas the cortical plates were quite thin. 3. Periapical lesions located in cancellous bone did not appear on a radiograph, regardless of the size of created lesion, but when the junctional bone was involved or the cortical plate was perforated, the define bone destructive change was observes on the roentgenogram. 4. Removal of the entire buccal or lingual plate did not affect the trabecular pattern of bone on the roentgenogram. 5. When the cancellous bone and junctional bone were removed simultaneously, altered trabecular patterns were observes on the roentgenogram.
[en] The distal phalanx and metacarpal physis of both forelimbs of 32 Thoroughbred foals 3-32 weeks of age were radiographed to identify those limbs with osseous bodies at a palmar process (PP) of the distal phalanx. Osseous bodies (ossicles) were identified radiographically in 19% of the foals. Sixteen of the 32 foals were selected for microradiographic and histological evaluation: 6 foals with radiographic evidence of ossicles and 10 foals without. Fourteen ossicles of the PP were observed radiographically. Ossicles were either a triangular bone fragment at the palmar aspect of the distal angle of the PP, or an oblong bone fragment separated from P3 by a radiolucent line extending 1-3 cm from the incisure of the PP to the solar margin. One foal had radiographic evidence of bilateral distal metacarpal physitis. Seventeen of 35 PPs examined microradiographically were considered normal, in that the dorsal and solar cortices were thin with trabecular bone orientated parallel to the cortical surfaces, and there was a depression in the dorsal cortical surface (i.e. parietal sulcus). Abnormal microradiographic findings in the other 18 PPs included a fracture line extending from the dorsal cortical surfaces and trabecular bridging of the fracture gap. The fracture line was often continuous with the parietal sulcus. Microradiographic evidence of a fracture was found in 75% of foals evaluated. Normal histological findings in 16 PPs included thin dorsal and solar cortices with trabeculae orientated parallel to the cortical surfaces, parallel-fibred dense connective tissue attachments of the deep digital flexor tendon to the solar cortical surfaces, and a neurovascular bundle associated with the parietal sulcus
[en] Purpose: To evaluate the accuracy and applicability of a commercially available microCT system for comparative measurements of the degree and distribution of mineralization of developing bone. Material and Methods: Homogeneous K2HPO4 solutions with different concentrations (range 0-800 mg/cm3) were used to assess the accuracy of a microCT system equipped with a polychromatic X-ray source. Both high (45 kV) and low (70 kV) tube peak voltages were explored. The resulting attenuation was compared with calculated theoretical attenuation values to estimate the accuracy. As an example of its applicability, the method was used to assess changes in the degree of mineralization of various regions of the mandible from two pigs of different developmental age. Results: On average, the estimated error of the measured linear attenuation was 10% or less. Accuracy was dependent on the average mineral concentration, the size of the sample, and the energy of the X-ray beam. The accuracy of the microCT system appeared sufficient to distinguish regional differences in the degree of mineralization within and between specimens of developing mandibular bone. Furthermore, the resolution of the system allowed identification of different degrees of mineralization within trabeculae. Conclusion: Accuracy of microCT with polychromatic radiation can be considered adequate for assessment of the degree of mineralization of developing bone. Therefore, this method provides a three-dimensional means by which to simultaneously investigate the bone structure as well as the degree of mineralization during development in a non-destructive manner and with high resolution
[en] To analyse the trabecular bone structure non-destructively, the authors used a peripheral quantitative computed tomography (QCT) system and applied a special thin-slice technique to create high-resolution volumetric data sets serving as a basis for non-invasive bone biopsy. In order to obtain binary data sets, the mineralized bone in the CT volume was separated from bone marrow and muscle tissue with the help of a sophisticated three-dimensional segmentation algorithm based on the analysis of directional derivatives, which are computed from a locally approximated fit function of the original CT volume. Binary volumes including either a solid representation of trabecular plates and rods or a topological representation of the cancellous bone architecture were acquired. By using a surface reconstruction algorithm based on interpolating triangulation it was possible to visualize the three-dimensional surface of the trabecular bone structure. (author)
[en] A new method of trabecular bone tissue dosimetry has been developed using solid-state materials. For measurement of photon radiation doses, trabecular bone was modeled by a mixture of two substances, a thermoluminescent phosphore and a nonluminophor, each of which is dosimetrically equivalent to either trabecular or red bone marrow, and each of which has a particle size range appropriate for one of the two tissue types that it represents. The ratio of components corresponds to the ratio of red bone marrow and trabecular bone as determined in actual bone samples. Characteristics of the dosimetric models for a few types of trabecular bone are given. Equivalence of the dosimetric characteristics of the various mixtures of thermoluminescent and nonluminophor materials to the corresponding characteristics of various types of trabecular bone have been derived and verified by experiment. 12 refs., 4 tabs
[en] To evaluate the reproducibility of 3-dimensional histomorphometry for the microarchitecture analysis of trabecular bone parameters using multidetector computed tomography (MDCT). Thirty-six specimens from porcine vertebral bodies were imaged five times with a 64- detector row MDCT system using the same scan protocols. Locations of the specimens were nearly identical through the scans. Three-dimensional structural parameters of trabecular bone were derived from the five data sets using image analyzing software. The features measured by the analysis programs were trabecular bone volume, trabecular bone volume/tissue volume, trabecular thickness, trabecular separation, trabecular number, trabecular bone pattern factor, structural model index. The structural trabecular parameters showed excellent reproducibility through repeated scanning. Intraclass correlation coefficients of all seven structural parameters were in the range of 0.998 to 1.000. Coefficients of variation of the six structural parameters, excluding structural model index, were not over 1.6%. The measurement of the trabecular structural parameters using multidetector CT and three-dimensional histomophometry analysis program was validated and showed excellent reproducibility. This method could be used as a noninvasive and easily available test in a clinical setting.
[en] The desmoplastic variant of ameloblastoma is a rare form of ameloblastoma characterized by unique radiographic and histologic features. A 46-year-old female was referred to our hospital, complaining of swelling in the left upper lip area. Radiographic findings revealed an ill-defined multilocular lesion with a large cystic lesion and thick sclerotic trabeculae on the left anterior maxilla. After the patient underwent partial osteotomy, histologic analysis revealed a desmoplastic ameloblastoma with no evidence of a hybrid lesion or cyst formation. The radiographic findings in the present case were different from those described in previous case reports. These findings are of special importance due to the unfamiliar radiographic and histologic features of this lesion