Altered topological blueprint of trabecular bone associates with skeletal pathology in humans.

Bone is a hierarchically organized biological material, and its strength is usually attributed to overt factors such as mass, density, and composition. Here we investigate a covert factor - the topological blueprint, or the network organization pattern of trabecular bone. This generally conserved metric of an edge-and-node simplified presentation of trabecular bone relates to the average coordination/valence of nodes and the equiangular 3D offset of trabeculae emanating from these nodes. We compare the topological blueprint of trabecular bone in presumably normal, fractured osteoporotic, and osteoarthritic samples (all from human femoral head, cross-sectional study). We show that bone topology is altered similarly in both fragility fracture and in joint degeneration. Decoupled from the morphological descriptors, the topological blueprint subjected to simulated loading associates with an abnormal distribution of strain, local stress concentrations and lower resistance to the standardized load in pathological samples, in comparison with normal samples. These topological effects show no correlation with classic morphological descriptors of trabecular bone. The negative effect of the altered topological blueprint may, or may not, be partly compensated for by the morphological parameters. Thus, naturally occurring optimization of trabecular topology, or a lack thereof in skeletal disease, might be an additional, previously unaccounted for, contributor to the biomechanical performance of bone, and might be considered as a factor in the life-long pathophysiological trajectory of common bone ailments.

Experimental setup for developing acousto-electric interaction imaging.

Acousto-Electric Interaction (AEI) is a physical phenomenon identified in the literature as potentially useful for imaging the electrical conductivity of biological tissues. AEI could lead to a non-invasive technique for detecting breast tumors, since the conductivity of pathological tissues differs significantly from the conductivity of healthy breast tissues. Applying AEI to image heterogeneous structures of the size of the breast represents a major technical challenge. We present in this paper an experimental setup designed to address the various instrumentation issues of AEI. Tests results are presented showing the ultrasonic vibration potential (also known as the Debye effect) and the AEI signals. A preliminary analysis of the AEI signal we recorded suggests that cavitation effects can be measured with this technique.