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Acoustic Radiation Force Impulse Optical Coherence Elastography for Measuring Elasticity of Cerebral Cortex

Acoustic Radiation Force Impulse Optical Coherence Elastography for Measuring Elasticity of Cerebral Cortex
Alternative Title
대뇌 피질의 탄성도 측정을 위한 음향 방사 힘 자극 광 간섭성 탄성측정 시스템
DGIST Authors
Chang, Yeon HeeSong, CheolHwang, Jae Youn
Cheol Song
Jae Youn Hwnag
Issued Date
Awarded Date
2018. 8
ARFI-OCE, Acoustic radiation force, Spectral domain OCT, Brain, Elastography, 음향방사력 자극 광 간섭성 탄성측정법, 스펙트럴 도메인 광간섭성 단층 촬영, 음향 방사력, 뇌, 탄성측정법
Elasticity change in brain tissues has been applicable to diagnosis and study of brain diseases including meningitis or stroke. Elastography modality has been developed to measure the elasticity of biological organ and tissue. Although various elastography techniques, such as magnetic resonance elastography (MRE) and ultrasound elastography (UE) are introduced to date, these approaches are limited in their spatial resolution to measure the elasticity in micron level of tissue or single cell. Due to intrinsic higher resolution power, optical coherence elastography (OCE) may shows a better chance to provide better outcomes compared to other techniques.
Here, we established acoustic radiation force impulse optical coherence elastography (ARFI-OCE) to measure the elasticity of a soft tissue. Acoustic radiation force generated by an ultrasound transducer is in-troduced to stimulate the sample. The displacement of a sample is measured by home-made spectral domain optical coherence tomography (OCT) system that uses a spectrometer to detect interference signal and thus can achieve much longer penetration depth than that of other optical imaging systems. To estimate the stiff-ness of samples, we calculate its displacement by using cross-correlation algorithm and phase resolve meth-od. The implemented system composes of a spectrometer-based OCT system, an ARFI system, and a linear stage set. The ARFI triggering signal is synchronized with a camera acquisition time.
In this study, ex-vivo tests on the cerebral cortex of mouse and the cerebral cortex of stroke rat model were conducted to evaluate strength of ARFI-OCE system. The system could distinguish the elasticity of dif-ferent cortex samples with better spatial resolution. Our results show that the ARFI-SD-OCE system is appli-cable to draw high-resolution elastogram in soft tissues as exemplified here using the brain and thus has a diagnostic potential to detect any abnormal changes in brain diseases.
Table Of Contents
Ⅰ. Introduction 1
1.1 Study Background 1
1.2 Previous Studies 2
1.3 Study Purpose 5
Ⅱ. Acoustic Radiation Force Impulse Optical Coherence Elastography (ARFI-OCE) 6
2.1 Spectral Domain OCT 6
2.2 Principle of OCE 7
2.2.1 Young’s modulus 8
2.2.2 Magnitude of radiation force 9
2.2.3 Cross-correlation 9
2.2.4 Phase resolve displacement calculation 9
2.3 Acoustic Radiation Force Impulse 10
2.4 Calibration of ARFI-OCE 11

Ⅲ. System Implementation 13
3.1 Configuration of ARFI-OCE System 13
3.2 Implementation of ARFI-OCE System 14
3.2.1 Implementation of spectrometer-based OCT system 14
3.2.2 implementation of ARFI system 15
3.2.3 Sample stage and motorized stage set-up 18
3.2.4 Implementation of ARFI-OCE system and triggering 20
3.2.5 Sample preparation 21
Ⅳ. Experiments and Results 23
4.1 1D Phantom Test 23
4.2 ex-vivo Mice Brain 24
4.3 ex-vivo Stroke Model Rat Brain 26
4.4 Preliminary Experiments for ARFI Calibration 27
Ⅴ. Conclusion and Discussion 30
Robotics Engineering
Related Researcher
  • 송철 Song, Cheol 로봇및기계전자공학과
  • Research Interests Handheld medical robotics; Smart robotic microsurgery; Smart neuro-rehabilitation; Bio-photonic sensing and imaging
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Department of Robotics and Mechatronics Engineering Theses Master


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