Method for in vivo assessment of cancer tissue inhomogeneity and accurate histology-like morphological segmentation based on Optical Coherence Elastography

We present a non-invasive method based on Optical Coherence Elastography (OCE) enabling the in vivo segmentation of morphological tissue constituents, in particular, monitoring of morphological alterations during both tumor development and its response to therapies. The method uses compressional OCE to reconstruct tissue stiffness map as the first step. Then the OCE-image is divided into regions, for which the Young’s modulus (stiffness) falls in specific ranges corresponding to the morphological constituents to be discriminated. These stiffness ranges (characteristic “stiffness spectra”) are initially determined by careful comparison of the “gold-standard” histological data and the OCE-based stiffness map for the corresponding tissue regions. After such precalibration, the results of morphological segmentation of OCE-images demonstrate a striking correlation with the histological results in terms of percentage of the segmented zones. To demonstrate high sensitivity of the OCE-method and its excellent correlation with conventional histological segmentation we present results obtained in vivo on a murine model of breast cancer in comparative experimental study of the efficacy of two anti-tumor chemotherapeutic drugs with different mechanisms of action. The new technique allowed in vivo monitoring and quantitative segmentation of (i) viable, (ii) dystrophic, (iii) necrotic tumor cells and (iv) edema zones very similar to morphological segmentation of histological images. Numerous applications in other experimental/clinical areas requiring rapid, nearly real-time, quantitative assessment of tissue structure can be foreseen.

Surface topography and mechanical properties of flax fibres modified glass ionomer restorative materials

Objectives: Regardless of the excellent adhesive and biological properties of glass ionomer cements (GICs), their poor mechanical properties and abrasion resistance limit their application to non-load bearing areas. This study aimed to investigate the effect of flax fibres incorporation on surface and mechanical properties of GIC filling materials. Methods: Short chopped flax fibres were randomly incorporated into GIC at 0, 0.5, 1, 2.5, 5 and 25 wt%. Surface hardness, distribution of different phases, stiffness map, phase separation and uniformity of the material were investigated. Results: Addition of flax fibres produced no significant change in Vicker hardness number of GIC. Qualitative imaging using atomic force microscopy showed the presence of a single phase in GIC, while biphasic structure was observed for flax fibres modified GICs (FFMGICs). For all tested formulations, the flax fibres, however, were uniformly distributed and well integrated within the GIC matrix without any visible interfacial separation. Incorporation of flax fibres was associated with a significant increase in surface roughness and stiffness. The roughness values obtained for all tested formulations, however, are far below the threshold values for bacterial adhesion and plaque accumulation. Conclusions: Flax fibres modified GICs could be potentially used in high stress bearing areas.

Localized Elastography Map of Human Cornea Through Surface Vibrations

Elastography techniques are being developed to diagnose and monitor the progression and treatment of diseases that correlate with changes in soft tissue stiffness. The objective of this paper is to outline the application of vibrations to the human cornea in order to reconstruct a stiffness map. Having a localized stiffness map is useful for early diagnosis of cornea related diseases such as glaucoma and keratoconus. Experimental data was collected by directly vibrating the excised cornea axisymetrically along the edge and measuring wave propagation inward with the use of laser vibrometry. Different methods have been implemented to increase the reflectivity of the cornea for laser vibrometry. To corroborate the data, as well as to test feasibility, experiments have been done on phantoms constructed from silicone-based polymers. To reconstruct the data into a stiffness map, an appropriate analytical model has to be derived. This paper outlines the derivation of the analytical model for the cornea starting with simple circular plates and moving towards the curved geometry of the cornea. To verify the analytical model, finite element simulations were used to replicate the results. These results have also been checked against experimental data to help determine any external variables that affect results. Overall, the feasibility and application of a process has been determined. Future goals include increasing in-vivo application to make the process safe and cost-effective.

Stiffness Estimation and Experiments for the Exechon Parallel Self-Reconfiguring Fixture Mechanism

The Exechon X150, a new smaller member of a successful series of parallel kinematic machines, has been recently developed as a component of a mobile self-reconfigurable fixture system within an inter-European project. This paper is the first to address the stiffness analysis of the parallel mechanism on which the design is based. The stiffness modeling method uses reciprocal screw theory as well as the virtual work principle, resulting in a simpler formulation and more convenient than ones obtained with traditional stiffness-modeling methods. Based on this model, the stiffness map within the workspace is obtained. The stiffness of the mechanism at a typical configuration is carried out. The complete finite element analysis and simulation used to verify the effectiveness of the stiffness model. Using geometric spatial decomposition, numerical examples of the mechanism at three typical configurations are presented.

Geometric Analysis and Characteristics of a Three-Fixed-Pivoted Multi-Phalanx Robotic Finger

This paper investigates the kinematic structure of robotic fingers, presents a linkage type of multi-phalanx (multi-joint) robotic fingers, and delivers geometric analysis. The new type of robotic fingers is driven by a three-pivoted linkage constituting a mechanism of two degrees of freedom. On the basis of mechanism decomposition with decoupled kinematics, this paper produces the closed-form kinematic equations for modelling the linkage. Decoupling the linkage into a loop linkage and a function generator of a four-bar linkage, the linkage geometric property and workspace are explored and a stiffness map is produced. The paper further develops the linkage Jacobian matrix and investigates the workspace characteristics.