Finger-mounted quantitative micro-elastography.

Rowan W Sanderson,Lixin Chin,Andrea Curatolo,Brendan F Kennedy,Philip Wijesinghe

doi:10.1364/boe.10.001760

Abstract

We present a finger-mounted quantitative micro-elastography (QME) probe, capable of measuring the elasticity of biological tissue in a format that avails of the dexterity of the human finger. Finger-mounted QME represents the first demonstration of a wearable elastography probe. The approach realizes optical coherence tomography-based elastography by focusing the optical beam into the sample via a single-mode fiber that is fused to a length of graded-index fiber. The fiber is rigidly affixed to a 3D-printed thimble that is mounted on the finger. Analogous to manual palpation, the probe compresses the tissue through the force exerted by the finger. The resulting deformation is measured using optical coherence tomography. Elasticity is estimated as the ratio of local stress at the sample surface, measured using a compliant layer, to the local strain in the sample. We describe the probe fabrication method and the signal processing developed to achieve accurate elasticity measurements in the presence of motion artifact. We demonstrate the probe's performance in motion-mode scans performed on homogeneous, bi-layer and inclusion phantoms and its ability to measure a thermally-induced increase in elasticity in ex vivo muscle tissue. In addition, we demonstrate the ability to acquire 2D images with the finger-mounted probe where lateral scanning is achieved by swiping the probe across the sample surface.

Highlights

Physicians have relied on the sense of touch to qualitatively assess disease based on changes in the mechanical properties of tissue, i.e., manual palpation [1]
To realize finger-mounted quantitative micro-elastography (QME), we extend on QME signal processing to generate accurate elasticity measurements in the presence of motion artifact induced by the finger
The results presented in this paper highlight the potential of finger-mounted QME for development towards clinical applications that currently rely on manual palpation

Summary

Introduction

Physicians have relied on the sense of touch to qualitatively assess disease based on changes in the mechanical properties of tissue, i.e., manual palpation [1]. Elastography was initially developed using ultrasound [6,7] and magnetic resonance imaging [8], and has been proposed for a range of clinical applications, in hepatology [9,10] and oncology [11]. As a photonics-based technique, OCE is amenable to miniaturization into small form factor probes, such as needles and endoscopes [23,24,25]. Such probes have the potential to enhance the clinical applicability of OCE.

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