Architectural changes in trabecular bone by osteoporosis were utilized as a model for the changes which probably occur in human bone while exposed to microgravity conditions. Although there are many ...concerns about microgravity-induced bone loss, little is known about the impact of microgravity on the three-dimensional architecture of the skeleton 1. 50 (level L3) and 57 (level L4) vertebral bones harvested from human cadavers were investigated by computed tomography (CT) and quantified in terms of bone mineral density (BMD). Based on the symbol-encoded transformed CT-images, five measures of complexity were developed which quantify the structural composition of the trabecular bone. This quantification determines the bone architecture as a whole. Depending on the specific measure of complexity and its relation to BMD, a 5–10% change of BMD is related to a 5–90% change in structural composition. The method requires a non-invasive CT-procedure of the lumbar spine resulting in a radiation exposure of about 30 μSv effective dose 2. The technique is useful for the evaluation of the bone status of space-flying personnel as well as for patients on ground.
Osteoporosis is mainly diagnosed by means of bone densitometry. Dual X-ray absorptiometry examinations represent the basis for a highly reproducible and correct measurement. At present, densitometry ...is the only method at our disposal capable of assessing material-related fracture risk. The calculation of general fracture risk is dependent on a number of varios factors and is, therefore, not to be deduced from bone density values only. Reference values are necessary in order to estimate bone strength. The most sensible way to achieve this is to compare measured values with a normal, healthy population (T score). Material-related fracture risk increases with the decrease of bone density.
In order to quantify the internal architecture of a bone in a holistic manner based on radiological images, the methodology of nonlinear dynamics was applied. Image processing algorithms, an ...expansion of symbolic dynamics, and five measures of complexity were introduced to quantify the trabecular part of human lumbar vertebral bodies. Healthy vertebral bones have a complex and ordered architecture with a high degree of spatiodynamics. Pathology changes the architecture significantly and can be quantified by measures of complexity.
The accuracy and reproducibility of morphometric measurements (Morphometric X-ray Absorptiometry = MXA) of vertebrae were determined. The significant difference of the change in height of vertebral ...bodies in follow-up studies was computed for MXA methods and digitised spinal radiographs as well.
The measurements were carried out on two new Dual X-ray Absorptiometry (DXA) devices (device A = Expert, Lunar Corp., device B = QDR 2000 Plus, Hologic Inc.). The data were obtained by using the European Spine Phantom (ESP) and lumbar spine specimens.
The accuracy of vertebral morphometry performed on radiographs is 2.0%, on the device A 2.3%, and on the device B 4.9%. Measurements taken with the ESP showed a reproducibility of 1.0 to 3.0%, whereas measurements of fractured vertebrae resulted in 5.1 to 6.0%.
The results of the morphometric measurements demonstrate that a reliable fracture analysis in phantoms and specimens is possible. Further in-vivo studies are necessary.
The European Vertebral Osteoporosis Study (EVOS) is one of the largest studies to investigate the prevalence of osteoporosis related vertebral fractures in a population based cross-sectional study. ...One of the main tasks was to create standards and logistics to obtain uniform and comparable radiographs in all 36 European centers. Furthermore the central reading of the X-rays and the morphometry of the vertebral bodies were 2 important challenges. This paper describes the standardized patient positioning and making of the radiographs as well as their morphometry, reading, and evaluation.
