Bone architecture assessment with measures of complexity

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 microgravit y-induced bone loss, little is known about the impact of microgravity on th e 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 comp osition. The method requires a non-invasive CT-procedure of the lumbar spin e resulting in a radiation exposure of about 30 mu Sv effective dose [2]. T he technique is useful for the evaluation of the bone status of space-flyin g personnel as well as for patients on ground. (C) 2001 Elsevier Science Lt d. All rights reserved.