Elasticity Measurement of Soft Tissues Using Hybrid Tactile and MARG-Based Displacement Sensor Systems

Abstract

Objective: This paper presents a novel soft tissue elasticity measurement technique based on the fusion of Magnetic, Angular Rate, and Gravity (MARG) sensors and fixe d tactile sensors. This work is intended both as a stand-alone technology, and as an extension of traditional tactile imaging of the breast to allow for accurate diagnosis of breast lesions. Methods: A series of artificial silicone materials known to imitate soft biological breast tissues are characterised using the proposed system and compared against an Instron® universal testing machine to determine system accuracy and repeatability. Results: Comparing the characteristics of 10 distinct materials , with elasticities in the range 9kPa to 90kPa, determined by the proposed system to those from the Instron® yields accuracy within 4% over the full-scale range. Interexperimental repeatability is within 1.5%. Conclusion: The proposed system delivers absolute elasticity of materials to within 4% which, whe n combined with its lack of moving parts and low implementation cost, can significantly improve the diagnostic capability of tactile imaging in the clinical environment. Significance: By applying this technique, to determine the background elasticity of breast tissue, in conjunction with the relative lesion elasticity result from tactile arrays, the full non-invasive diagnostic potential of tactile imaging can be realised with the effect of reducing benign biops y rates, secondary care costs, and patient stress.

Displacement Measurement of Soft Material Indentation using Light Intensity

“…The individual repeatability of the sample determines the overall system repeatability, and when the mean response is considered, as shown in Figure 7, the variation in repeatability is less than 1.5%. In addition, as shown in Table 2, when repeated measurements are performed on the same sample, the variance of each measurement concerning the mean value is less than 2%, which is similar to the performance obtained by Hampson et al [3]. With excellent repeatability, the proposed method overcomes the repeatability limitation of the existing palpation methods especially those with light intensity modulated (LIM)-based [28].…”

“…It can be observed that the R-squared values for all silicone samples are more than 96%. It implies that the difference in light intensity at any initial light intensity can be predicted with high precision [3]. The results demonstrate a high consistency of the proposed concept.…”

“…In the case of a human-handled indenter, the movement of the indenter may not be perfectly vertical and may result in inconsistent compression. The same limitation is highlighted in other handheld devices [3,5,32]. Specific mechanisms for removing the error must be implemented when translating the proposed concept into a product.…”

“…Hampson et al [3] used the acceleration sensor to calculate the acceleration of the characterization probe, which was then incorporated for displacement readings. Although the recorded results showed a high accuracy of 4% of the variance with the industrial universal testing unit, the application required the user to apply the device at a certain angle to allow an accurate measurement of the acceleration.…”

Tactile, Orientation, and Optical Sensor Fusion for Tactile Breast Image Mosaicking

“…These different phantoms allowed for parametric evaluation of registration and elasticity measurement accuracy vs. feature density and background elasticity, known to be variable in normal breast tissue. Additionally, it is known that the elasticity measurement accuracy of tactile imaging systems can be sensitive to base elasticity [10], [35], making this parametric analysis valuable by indicating generalized performance stats.…”