W.G.M. Geraets

The radiographic trabecular pattern of hips in patients with hip fractures and in elderly control subjects.

Due to the increasing number of osteoporotic fractures of hip, spine, and wrist there is a growing need for methods to track down the subjects with inferior bone structure and to monitor the effects of therapeutic measures. This study aims at a noninvasive diagnostic tool, deriving architectural properties of trabecular bone from in vivo measurements on plane radiographic films. Pelvic radiographs of the nonfractured hips of 81 patients with hip fractures and of the right hips of 74 controls were studied. The regions of interest, 2 x 2 cm2, located in the femoral neck, were sampled and digitized with a video camera connected to an image analysis system. Several geometrical and directional measurements were made. The measurements were evaluated by statistical comparison with fracture risk, gender, and Singh index. By discriminant analysis, type of fracture, as well as gender and Singh index could be predicted correctly for 58% of the subjects, whereas guessing would be correct in only 8%. It was found that the geometrical parameters discriminate between hips of controls and patients. With respect to the directional measurements associations were found with gender and Singh index. Although the new parameters assess fracture risk less accurately than bone density measurements, some parameters suggest by their behavior that they are relevant with respect to femoral bone architecture and its mechanical behavior. Although interpretation of the measurements in histological concepts requires methods that have been reported in literature only recently, it is concluded that digital analysis of the radiographic trabecular pattern is an interesting option to increase the diagnostic yield of plane film radiographs and to study the structure of bone in vivo.

The radiographic trabecular bone pattern during menopause.

The purpose of this study is to increase the diagnostic value of radiographs by observing the radiographic trabecular pattern during occasions of changing three-dimensional bone structure. We explored how the shape of the radiographic trabecular pattern of the distal radius relates to bone mineral density, time, and menopausal status. We found that the trabecular pattern correlates with bone mineral density and time, especially in the early years of the climacterium.

Orientation of the trabecular pattern of the distal radius around the menopause

The trabecular pattern depicted on radiographs of the distal radius of women around the menopause is analysed by a new method to measure orientation. It is shown that the trabecular pattern on radiographs of the distal radius is aligned preferentially along the axial direction and to a lesser extent along the transverse direction. Two minima of orientation are found at 60 degrees off the axial direction. A significant correlation is found between the average value of the orientation in the radius and the average lumbar bone mineral density. It is known that the bone mineral content decreases around the menopause. Previous reports on the present images describe several features that were found to be related to bone mineral content and to time. The orientation of the trabecular pattern, however, is found to be independent of time, at least during the two years of the investigation. Therefore, it is concluded that the orientation of the radiographic trabecular pattern tends to remain stable even if some features of the pattern evolve. Previous studies on radiographs of the radius of children and elderly women and men provide evidence for the tendency of orientation to remain stable not only in women around the menopause, but also in men and women during the entire adult life.

Longitudinal analysis of radiographic trabecular pattern by image processing.

To describe structural and textural changes in bone structure, the radiographic trabecular pattern of children, aged 4-14 years, was examined using a digital image processing system. This investigation is based on data from the Nijmegen Growth Study, a mixed-longitudinal growth study comprised of three birth cohorts, which were observed for five years. Of 3075 left hand-forearm radiographs of 426 children, a standard area of 10 x 10 mm of the radius was digitized and the trabecular pattern was described by ten image features. It is demonstrated that all image features show significant changes during the observation period (multivariate analysis of variance of p < 0.01). The age of the children correlates significantly with the image features (Spearmans Rho = 0.4; p < 0.05). Because of cohort effects, the three cohorts were studied separately. Highest correlations between age and trabecular pattern were shown in the cohort of the youngest children. The changes of the image features during the observation period seems to indicate that the fine trabecular pattern of young children changes into a coarser adult pattern. It is concluded that digital quantification of the radiographic trabecular pattern is appropriate to describe changes in trabecular bone.

Analysis of the radiographic trabecular pattern

This study evaluates a method to measure the structure of the trabecular pattern, seen on radiographs of the distal radius. It is shown that the trabecular pattern of perimenopausal women is dynamic. The trabecular pattern of pre- and postmenopausal women, however, turns out to be stable.

Relations between radiographic trabecular pattern and biomechanical characteristics of human vertebrae

PURPOSEnRelations between the radiographic trabecular pattern and the biomechanical characteristics of bone were studied.nnnMATERIAL AND METHODSnThe material comprised L2 and L3 vertebral bodies of 14 individuals (aged 22-76 years; 6 women and 8 men). Compressive strength and ash density of the complete L2 vertebral body were determined. Of the L3 vertebral body, ash density and compressive strength in both horizontal and vertical directions were measured on cylinders of merely trabecular bone. Radiographs were taken of a midsagittal slice of L3 vertebrae. They were digitized to measure trabecular bone geometry and orientation. The procedure was repeated several times to obtain reliable measures.nnnRESULTSnThe radiographic trabecular pattern was significantly related to compressive strength, ash density and age. One of the radiographic geometric features in particular seems to offer information concerning the structural integrity of the trabecular architecture.nnnCONCLUSIONnAnalysis of the radiographic trabecular pattern appears to be a promising technique for prediction of trabecular bone strength.

Prediction of osteoporosis with dental radiographs and age

OBJECTIVESnIn this study age and the trabecular pattern present on dental radiographs were used to predict the presence of osteoporosis. The objective was to evaluate the contribution of the trabecular pattern to the prediction.nnnMETHODSnIn this project, 671 women between 45 and 71 years of age were recruited. Medical history was obtained and dental radiographs were made. Bone mineral density (BMD) was measured at three sites to assess the presence of osteoporosis according to the World Health Organization criteria. The radiographs were subjected to image analysis methods yielding measurements of the trabecular pattern. Thereafter, discriminant analysis was used to predict the presence of osteoporosis by means of the trabecular pattern and age. Sensitivity and specificity of age and the trabecular pattern were compared. Also, it was checked whether the inclusion of the trabecular pattern improved the sensitivity and specificity that were obtained when only age was used as the predictor.nnnRESULTSnThe sensitivity and specificity of the trabecular pattern present on dental radiographs were almost equal to those of age. However, combining age with the trabecular pattern increased the sensitivity from 0.71 to 0.75 and the specificity from 0.72 to 0.78; the latter increase was statistically significant.nnnCONCLUSIONSnThe trabecular pattern predicts the presence of osteoporosis just as well as age does. When combining the trabecular pattern with age, the sensitivity and specificity increased. Only the latter increase was statistically significant.

Computer-aided interpretation and quantification of angular periodontal bone defects on dental radiographs

The evaluation of a computer-aided procedure for the interpretation and quantification of angular periodontal bone defects on dental radiographs is described. The computer-aided procedure was able to rank a series of artificial periodontal bone lesions as accurately as experienced clinicians. A comparison of data from clinical inspections of lesions during surgery with quantitative results of the digitized procedure shows that the latter produced reliable information on lesion size. Reproducibility is satisfactory. It is concluded that computer-aided detection and description of periodontal bone defects decreases the interobserver variability in general and the time-dependent variability in repeated assessments of a single observer.<<ETX>>

Selecting regions of interest on intraoral radiographs for the prediction of bone mineral density

OBJECTIVESnA previous study showed that the trabecular pattern on dental radiographs correlates with femoral and spinal bone mineral density (BMD). The objective of this study was to determine if the correlation is affected by the size and location of the region of interest (ROI).nnnMETHODSnIn a European research project on osteoporosis, BMD was measured at the left hip and the lumbar spine of 525 women. From all subjects, intraoral radiographs were made of the premolar region in the upper and lower jaws. Two ROIs were indicated manually on each scanned image. The smallest region involved only trabecular bone and the largest also included parts of the neighbouring teeth. The ROIs were subjected to automatic image analysis, yielding 26 measurements per ROI. Stepwise linear regression was used to predict femoral and spinal BMD.nnnRESULTSnInner and outer regions predicted BMD equally well. The radiographs of lower and upper jaw also predicted BMD equally well. Combining inner and outer regions did not improve the prediction of femoral and spinal BMD, but combining lower and upper jaws did.nnnCONCLUSIONSnThis study shows that it is possible to include parts of neighbouring teeth in the ROI used to assess the trabecular pattern and predict BMD. This simplifies the process of selecting the ROIs because no efforts have to be made to exclude neighbouring teeth. Combining ROIs of lower and upper jaws significantly improves the prediction of BMD.

Reliability of an image analysis system for quantifying the radiographic trabecular pattern

A reliability evaluation technique was used to examine the reliability of an image analysis system of the trabecular pattern and to determine the contribution of three possible sources of error variance. Two series of radiographs were taken of 14 lumbar vertebral slices (28 radiographs). Every radiograph was placed on a viewing box for digitization four times by a single operator (112 positions of radiographs) and from every position of a radiograph an area of 15 mm/spl times/15 mm was digitized twice (224 samples for analysis). Ten geometrical characteristics of the trabecular pattern were studied and its orientation was analyzed in 12 directions. Reliability was determined by calculating Cronbachs /spl alpha/. This design enabled dividing the measurement error (1-/spl alpha/) into fractions associated with the X-ray procedure, the operator and the system. Using this reliability evaluation technique, it was found that the orientation variables are more reliable than the geometric variables. It was found that effort to increase the reliability should be directed toward improving the technical procedure of this image analysis system. Also, repeated measurements will increase the reliability. The number of repeated measurements based on a desired reliability can be calculated. This procedure of evaluation gives the opportunity to select a source of error variance which have to be reduced to increase reliability most effectively.