Volumetric Topological Analysis: A Novel Approach for Trabecular Bone Classification on the Continuum Between Plates and Rods

Abstract

Trabecular bone (TB) is a complex quasi-random network of interconnected plates and rods. TB constantly remodels to adapt to the stresses to which it is subjected (Wolff s Law). In osteoporosis, this dynamic equilibrium between bone formation and resorption is perturbed, leading to bone loss and structural deterioration, both increasing fracture risk. Bone s mechanical behavior can only be partially explained by variations in bone mineral density, which led to the notion of bone structural quality. Previously, we developed digital topological analysis (DTA) which classifies plates, rods, profiles, edges, and junctions in a TB skeletal representation. Although the method has become quite popular, a major limitation of DTA is that it provides only hard classifications of different topological entities, failing to distinguish between narrow and wide plates. Here, we present a new method called volumetric topological analysis (VTA) for regional quantification of TB topology. At each TB location, the method uniquely classifies its topology on the continuum between perfect plates and perfect rods, facilitating early detections of TB alterations from plates to rods according to the known etiology of osteoporotic bone loss. Several new ideas, including manifold distance transform, manifold scale, and feature propagation have been introduced here and combined with existing DTA and distance transform methods, leading to the new VTA technology. This method has been applied to multi-detector CT and μCT images of four cadaveric distal tibia and five distal radius specimens. Both intra- and inter-modality reproducibility of the method has been examined using repeat CT and μCT scans of distal tibia specimens. Also, the method s ability to predict experimental biomechanical properties of TB via CT imaging under in vivo conditions has been quantitatively examined and the results found are very encouraging.

Tortuosidade e conectividade da rede trabecular do rádio distal a partir de imagens microtomográficas

“…Recentemente Saha et al (2010) propuseram uma técnica para classificação da distribuição trabecular em hastes e discos, o que possibilitará uma investigação mais apropriada sobre a influência dessas formas na tortuosidade. ; esses representam o maior e o menor valor do DTD entre todas as amostras.…”

Characterization of trabecular bone plate‐rod microarchitecture using multirow detector CT and the tensor scale: Algorithms, validation, and applications to pilot human studies

“…In addition to the above measures of TB, for the purpose of comparison, two other measures, namely, mean platewidth PW VTA and plate-to-rod ratio PRR VTA were computed using the VTA algorithm as described by Saha et al 18 Also, the structure model index (SMI) was computed using the algorithm described by Hildebrand and Rüegsegger. 22 F.…”

“…Although it provides the highest resolution while being nondestructive, µ-CT requires bone biopsy, which is rarely indicated clinically and is not suited for monitoring treatment response. Recent advancements in volumetric bone imaging, such as magnetic resonance (MR), 6,13,14 high resolution peripheral quantitative computed tomography (HR-pQCT), 15,16 and multirow detector computed tomography (MD-CT), 17,18 allow characterization of bone microarchitecture without the need for biopsy.…”

“…The balance between plates and rods during bone formation at younger ages, as well as during bone loss or antiresorptive treatment, changes gradually and, therefore, demands classification of TB microarchitecture along the continuum between a perfect plate and a perfect rod. Recently, Saha et al 18 developed a volumetric topological analysis (VTA) algorithm characterizing the topology of individual trabeculae on the continuum between a perfect plate and a perfect rod. Although VTA provides an effective measure of TB microarchitecture from in vivo images, its premise is built upon digital topology and path propagation approaches, making it more susceptible to cumulative errors incurred during digital path propagation.…”

Automated cortical bone segmentation for multirow‐detector CT imaging with validation and application to human studies

“…33,[35][36][37][38] Recent advancements in multirow-detector CT (MD-CT) imaging technologies have enabled a resolution that allows in vivo segmentation of individual trabeculae and their microarchitectural analysis at peripheral anatomic sites, e.g., distal tibia. 39 A major advantage of bone CT imaging at a peripheral site as compared to a central site, e.g., proximal femur is that a peripheral bone CT requires significantly lower radiation dose as compared to a femur CT-a few days of background radiation for a peripheral bone CT versus two or three years of background radiation for a bone CT at a central site. Thus, peripheral bone CT imaging may be performed on low risk individuals, while a bone CT at a central site on low risk individuals may be difficult to justify.…”