Showing papers on "Elastography published in 2015"

WFUMB Guidelines and Recommendations for Clinical Use of Ultrasound Elastography: Part 2: Breast

Abstract: The breast section of these Guidelines and Recommendations for Elastography produced under the auspices of the World Federation of Ultrasound in Medicine and Biology (WFUMB) assesses the clinically used applications of all forms of elastography used in breast imaging. The literature on various breast elastography techniques is reviewed, and recommendations are made on evidence-based results. Practical advice is given on how to perform and interpret breast elastography for optimal results, with emphasis placed on avoiding pitfalls. Artifacts are reviewed, and the clinical utility of some artifacts is discussed. Both strain and shear wave techniques have been shown to be highly accurate in characterizing breast lesions as benign or malignant. The relationship between the various techniques is discussed, and recommended interpretation based on a BI-RADS-like malignancy probability scale is provided. This document is intended to be used as a reference and to guide clinical users in a practical way.

WFUMB guidelines and recommendations for clinical use of ultrasound elastography: Part 1: basic principles and terminology.

Abstract: Conventional diagnostic ultrasound images of the anatomy (as opposed to blood flow) reveal differences in the acoustic properties of soft tissues (mainly echogenicity but also, to some extent, attenuation), whereas ultrasound-based elasticity images are able to reveal the differences in the elastic properties of soft tissues (e.g., elasticity and viscosity). The benefit of elasticity imaging lies in the fact that many soft tissues can share similar ultrasonic echogenicities but may have different mechanical properties that can be used to clearly visualize normal anatomy and delineate pathologic lesions. Typically, all elasticity measurement and imaging methods introduce a mechanical excitation and monitor the resulting tissue response. Some of the most widely available commercial elasticity imaging methods are 'quasi-static' and use external tissue compression to generate images of the resulting tissue strain (or deformation). In addition, many manufacturers now provide shear wave imaging and measurement methods, which deliver stiffness images based upon the shear wave propagation speed. The goal of this review is to describe the fundamental physics and the associated terminology underlying these technologies. We have included a questions and answers section, an extensive appendix, and a glossary of terms in this manuscript. We have also endeavored to ensure that the terminology and descriptions, although not identical, are broadly compatible across the WFUMB and EFSUMB sets of guidelines on elastography (Bamber et al. 2013; Cosgrove et al. 2013).

Optical coherence elastography for tissue characterization: a review.

Abstract: The position of OCE among other elastography techniques. Optical coherence elastography (OCE) represents the frontier of optical elasticity imaging techniques and focuses on the micro-scale assessment of tissue biomechanics in 3D that is hard to achieve with traditional elastographic methods. Benefit from the advancement of optical coherence tomography, and driven by the increasing requirements in nondestructive biomechanical characterization, this emerging technique recently has experienced a rapid development. In this paper, we start with the description of the mechanical contrast that has been employed by OCE and review the state-of-the-art techniques based on the reported applications and discuss the current technical challenges, emphasizing the unique role of OCE in tissue mechanical characterization.

Elastography for Muscle Biomechanics: Toward the Estimation of Individual Muscle Force.

Abstract: Estimation of individual muscle force remains one of the main challenges in biomechanics. This review presents a series of experiments that used ultrasound shear wave elastography to support the hypothesis that muscle stiffness is linearly related to both active and passive muscle forces. Examples of studies that used measurement of muscle stiffness to estimate changes in muscle force are presented.

Prospective Comparison of Spleen and Liver Stiffness by Using Shear-Wave and Transient Elastography for Detection of Portal Hypertension in Cirrhosis

Abstract: In patients with advanced cirrhosis, shear-wave elastography (SWE) was significantly more reliable than transient elastography for the measurement of liver stiffness (LS) and spleen stiffness (more than 95% vs less than 50%, respectively), and the diagnostic accuracy of LS by using SWE was good for detection of clinically significant portal hypertension.

Quantitative micro-elastography: imaging of tissue elasticity using compression optical coherence elastography.

Abstract: Probing the mechanical properties of tissue on the microscale could aid in the identification of diseased tissues that are inadequately detected using palpation or current clinical imaging modalities, with potential to guide medical procedures such as the excision of breast tumours. Compression optical coherence elastography (OCE) maps tissue strain with microscale spatial resolution and can delineate microstructural features within breast tissues. However, without a measure of the locally applied stress, strain provides only a qualitative indication of mechanical properties. To overcome this limitation, we present quantitative micro-elastography, which combines compression OCE with a compliant stress sensor to image tissue elasticity. The sensor consists of a layer of translucent silicone with well-characterized stress-strain behaviour. The measured strain in the sensor is used to estimate the two-dimensional stress distribution applied to the sample surface. Elasticity is determined by dividing the stress by the strain in the sample. We show that quantification of elasticity can improve the ability of compression OCE to distinguish between tissues, thereby extending the potential for inter-sample comparison and longitudinal studies of tissue elasticity. We validate the technique using tissue-mimicking phantoms and demonstrate the ability to map elasticity of freshly excised malignant and benign human breast tissues.

Ultrasound Elastography and MR Elastography for Assessing Liver Fibrosis: Part 2, Diagnostic Performance, Confounders, and Future Directions

Abstract: OBJECTIVE. The purpose of the article is to review the diagnostic performance of ultra-sound and MR elastography techniques for detection and staging of liver fibrosis, the main current clinical applications of elastography in the abdomen. CONCLUSION. Technical and instrument-related factors and biologic and patient-related factors may constitute potential confounders of stiffness measurements for assessment of liver fibrosis. Future developments may expand the scope of elastography for monitoring liver fibrosis and predict complications of chronic liver disease.

Shear-wave elastography for the estimation of liver fibrosis in chronic liver disease: determining accuracy and ideal site for measurement.

Abstract: We conclude that estimates of the Young modulus obtained with shear-wave elastography in the upper right lobe of the liver can be used to differentiate advanced fibrosis (≥F2) from nonadvanced fibrosis.

Ultrasound Elastography and MR Elastography for Assessing Liver Fibrosis: Part 1, Principles and Techniques

Abstract: OBJECTIVE. The purpose of this article is to provide an overview of ultrasound and MR elastography, including a glossary of relevant terminology, a classification of elastography techniques, and a discussion of their respective strengths and limitations. CONCLUSION. Elastography is an emerging technique for the noninvasive assessment of mechanical tissue properties. These techniques report metrics related to tissue stiffness, such as shear-wave speed, magnitude of the complex shear modulus, and the Young modulus.

Viscoelasticity in Achilles Tendonopathy: Quantitative Assessment by Using Real-time Shear-Wave Elastography

Abstract: Shear-wave elastography demonstrated and helped to quantify pathologic tendon softening in patients with tendonopathy in the midportion of the Achilles tendon but did not reveal modifications of viscoelastic anisotropy in the tendon.

Shear-Wave Elastography of the Breast: Value of a Quality Measure and Comparison with Strain Elastography

Abstract: The use of the quality measure of shear-wave (SW) velocity increased the sensitivity of SW elastography for breast cancer from 50% (20 of 40) to 93% (37 of 40), with P = .0001, and changed specificity from 94% (77 of 82) to 89% (73 of 82), with P = .13.

Elastography: history, principles, and technique comparison

Abstract: Elastography is a relatively new imaging technology that creates images of tissue stiffness. It can be thought of an extension of the ancient technique of palpation but it gives better spatial localization information and is less subjective. Two main types of elastography are currently in use, strain elastography where the tissue displacement in response to gentle pressure is used to compute and image tissue strain, and shear wave elastography where the speed of shear waves traversing tissue is measured and used to create an image of tissue stiffness. Each method has advantages and disadvantages but generally strain imaging is excellent for focal lesions and shear wave imaging, being more quantitative, is best for diffuse organ diseases. Strain imaging requires additional training in acquisition technique to obtain high quality images. Pitfalls to avoid and tips for good images are provided. Improvements in strain imaging are focused on better quality indicators and better methods for quantification. Improvements in shear wave imaging will be higher frame rates, greater accuracy in focal lesions, and making results more comparable between different ultrasound systems. Both methods will continue to improve and will provide ever more powerful new tools for diagnosis of diffuse and focal diseases.

US-based Real-time Elastography for the Detection of Fibrotic Gut Tissue in Patients with Stricturing Crohn Disease

Abstract: US-based real-time elastography can be used to reliably detect fibrotic gut tissue in patients with Crohn disease.

Reliable protocol for shear wave elastography of lower limb muscles at rest and during passive stretching.

Abstract: Development of shear wave elastography gave access to non-invasive muscle stiffness assessment in vivo. The aim of the present study was to define a measurement protocol to be used in clinical routine for quantifying the shear modulus of lower limb muscles. Four positions were defined to evaluate shear modulus in 10 healthy subjects: parallel to the fibers, in the anterior and posterior aspects of the lower limb, at rest and during passive stretching. Reliability was first evaluated on two muscles by three operators; these measurements were repeated six times. Then, measurement reliability was compared in 11 muscles by two operators; these measurements were repeated three times. Reproducibility of shear modulus was 0.48 kPa and repeatability was 0.41 kPa, with all muscles pooled. Position did not significantly influence reliability. Shear wave elastography appeared to be an appropriate and reliable tool to evaluate the shear modulus of lower limb muscles with the proposed protocol.

Feasibility of Using 3D MR Elastography to Determine Pancreatic Stiffness in Healthy Volunteers

Abstract: Current imaging modalities are not sensitive enough to detect the early stages of either chronic pancreatitis (CP) or pancreatic ductal adenocarcinoma (PDAC). Conventional computed tomography has proven to be unreliable for detecting early-stage CP and PDAC (1, 2). Endoscopic retrograde pancreatography (ERCP) and MR cholangiopancreatography (MRCP) provide excellent details and clear visualization of the ductal system, but mild disease may remain undetectable. Endoscopic ultrasound (EUS) is a sensitive procedure for evaluating and staging these diseases, but is invasive and detection of early-stage diseases without pathology is also controversial (3). In an attempt to overcome these deficiencies of modalities that only detect morphological changes, MR Elastography (MRE) offers a different approach for detecting diseases based on changes in tissue mechanical properties. MRE is a phase-contrast MRI technique for quantitatively assessing the stiffness of biological tissues by visualizing propagating shear waves in soft tissues (4). It has been shown to accurately assess hepatic fibrosis in patients with chronic liver diseases (5). Moreover, inflammation has also been shown to elevate tissue stiffness (6). Theoretically, both CP and PDAC, due to a build-up of fibrotic tissue and inflammatory changes, are likely to result in higher pancreatic stiffness compared to normal pancreas. It is worth exploring the feasibility of measuring pancreatic stiffness first in a cohort of normal subjects before investigating its potential as a clinical tool for detecting CP and PDAC. In hepatic MRE, a 2D inversion model is typically enough to provide valid stiffness estimates due to the controlled and reproducible method used for introducing the motion into the liver. However, the location of the pancreas, its small size and complex shape, and the impact of the geometric boundary conditions and wave transmission factors on the propagation of the waves through the abdomen and into the pancreas require a 3D analysis of wave field data in the pancreas. This is analogous to work done in evaluating 3D vector MRE wave fields in the brain which showed that vibrating the head produced a zone where the waves propagated approximately in-plane and could be analyzed in 2D with only small biases in the results. Analysis outside of that zone requires a 3D analysis to account for deviations in the wave propagation direction that occur in other parts of the brain (7). Performing MRE of the pancreas presents unique technical challenges, including the introduction of shear waves deep into the body as well as performing efficient sampling and processing of a 3D vector displacement field. We have designed a passive driver, with a large area in tight contact with the body, to introduce shear waves into the pancreas and implemented a multislice spin-echo echo planar imaging (EPI) MRE pulse sequence to allow for fast volumetric acquisitions (8). Hence, the goal of this study was 1) to assess the feasibility of performing 3D pancreas MRE using a tailored driver to deliver low-frequency (40, 60 Hz) vibrations, 2) to compile preliminary normative values for the shear stiffness of the healthy pancreas, and 3) to evaluate the stiffness measurements of different subregions of the pancreas (tail, body, neck, head and uncinate).

Shear-Wave Elastography for the Preoperative Risk Stratification of Follicular-patterned Lesions of the Thyroid: Diagnostic Accuracy and Optimal Measurement Plane.

Abstract: Shear-wave elastography is a promising test for the preoperative malignancy risk stratification of patients with an indeterminate fine-needle aspiration diagnosis of a follicular-patterned thyroid lesion.

Two-dimensional shear-wave elastography and conventional US: the optimal evaluation of liver fibrosis and cirrhosis.

Abstract: In this study, comparison of areas under the receiver operating characteristic curve revealed that two-dimensional shear-wave elastography was superior to conventional US in diagnosis of significant fibrosis (score of F2 or greater) and early cirrhosis (score of F4).

Prediction of liver cirrhosis, using diagnostic imaging tools

Abstract: Early diagnosis of liver cirrhosis is important Ultrasound-guided liver biopsy is the gold standard for diagnosis of liver cirrhosis However, its invasiveness and sampling bias limit the applicability of the method Basic imaging for the diagnosis of liver cirrhosis has developed over the last few decades, enabling early detection of morphological changes of the liver by ultrasonography (US), computed tomography, and magnetic resonance imaging (MRI) They are also accurate diagnostic methods for advanced liver cirrhosis, for which early diagnosis is difficult There are a number of ways to compensate for this difficulty, including texture analysis to more closely identify the homogeneity of hepatic parenchyma, elastography to measure the stiffness and elasticity of the liver, and perfusion studies to determine the blood flow volume, transit time, and velocity Amongst these methods, elastography using US and MRI was found to be slightly easier, faster, and able to provide an accurate diagnosis Early diagnosis of liver cirrhosis using MRI or US elastography is therefore a realistic alternative, but further research is still needed

Acoustic Radiation Force Impulse Elastography for the Non-Invasive Evaluation of Hepatic Fibrosis in Non-Alcoholic Fatty Liver Disease Patients: A Systematic Review & Meta-Analysis

Abstract: Background In order to better monitor non-alcoholic fatty liver disease (NAFLD) patients at higher risk for HCC, there is a need for non-invasive diagnostic approaches to screen for the presence of advanced fibrosis in these patients The aim of this systematic review and meta-analysis will be to evaluate the diagnostic efficacy of ARFI elastography in detecting hepatic fibrosis in NAFLD patients Methods Relevant studies were identified from systematic searches of several major electronic databases (PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials) The primary outcomes were the summary sensitivity, summary specificity, the diagnostic odds ratio, and the summary receiver operating characteristic curve (SROC) of ARFI elastography in detecting significant fibrosis (defined as 4>F≥2) in NAFLD patients Study quality was assessed using the Quality Assessment of Studies of Diagnostic Accuracy included in Systematic Review (QUADAS-2) Results The summary sensitivity and specificity of ARFI in detecting significant fibrosis were 802% (95% confidence interval (CI): 0758–0842; p = 00000) and 852% (95% CI: 0808–0890), p = 01617), respectively The pooled diagnostic odds ratio of ARFI in detecting significant fibrosis was 3013 (95% CI: 1208–75; chi-squared = 1459, p = 00237) The area under the SROC curve (AUC) was 0898 (standard error (SE): 0031) with a Q* index of 0830 (SE: 0033) Conclusions ARFI elastography appears to be modestly accurate in detecting significant fibrosis in NAFLD patients Future studies in this field should provide head-to-head comparisons of ARFI elastography versus other elastographic imaging modalities in NAFLD patients

Continuous Shear Wave Elastography: A New Method to Measure Viscoelastic Properties of Tendons in Vivo.

Abstract: Viscoelastic mechanical properties are frequently altered after tendon injuries and during recovery. Therefore, non-invasive measurements of shear viscoelastic properties may help evaluate tendon recovery and compare the effectiveness of different therapies. The objectives of this study were to describe an elastography method for measuring localized viscoelastic properties of tendons and to discuss the initial results in healthy and injured human Achilles and semitendinosus tendons. The technique used an external actuator to generate the shear waves in the tendon at different frequencies and plane wave imaging to measure shear wave displacements. For each of the excitation frequencies, maps of direction-specific wave speeds were calculated using local frequency estimation. Maps of viscoelastic properties were obtained using a pixel-wise curve fit of wave speed and frequency. The method was validated by comparing measurements of wave speed in agarose gels with those obtained using magnetic resonance elastography. Measurements in human healthy Achilles tendons revealed a pronounced increase in wave speed as a function of frequency, which highlights the importance of tendon viscoelasticity. Additionally, the viscoelastic properties of the Achilles tendon were larger than those reported for other tissues. Measurements in a tendinopathic Achilles tendon indicated that it is feasible to quantify local viscoelastic properties. Similarly, measurement in the semitendinosus tendon revealed substantial differences in viscoelastic properties between the healthy and contralateral tendons. Consequently, this technique has the potential to evaluate localized changes in tendon viscoelastic properties caused by injury and during recovery in a clinical setting.

Assessing age-related changes in the biomechanical properties of rabbit lens using a coaligned ultrasound and optical coherence elastography system.

Abstract: PURPOSE To evaluate the capability of a novel, coaligned focused ultrasound and phase-sensitive optical coherence elastography (US-OCE) system to assess age-related changes in biomechanical properties of the crystalline lens in situ. METHODS Low-amplitude elastic deformations in young and mature rabbit lenses were measured by an US-OCE system consisting of a spectral-domain optical coherence tomography (OCT) system coaligned with a focused ultrasound system used to produce a transient force on the lens surface. Uniaxial compressional tests were used to validate the OCE data. RESULTS The OCE measurements showed that the maximum displacements of the young rabbit lenses were significantly larger than those of the mature lenses, indicating a gradual increase of the lens stiffness with age. Temporal analyses of the displacements also demonstrate a similar trend of elastic properties in these lenses. The stress-strain measurements using uniaxial mechanical tests confirmed the results obtained by the US-OCE system. CONCLUSIONS The results demonstrate that the US-OCE system can be used for noninvasive analysis and quantification of lens biomechanical properties in situ and possibly in vivo.

Two-dimensional shear-wave elastography on conventional ultrasound scanners with time-aligned sequential tracking (TAST) and comb-push ultrasound shear elastography (CUSE)

Abstract: Two-dimensional shear-wave elastography presents 2-D quantitative shear elasticity maps of tissue, which are clinically useful for both focal lesion detection and diffuse disease diagnosis. Realization of 2-D shear-wave elastography on conventional ultrasound scanners, however, is challenging because of the low tracking pulse-repetition-frequency (PRF) of these systems. Although some clinical and research platforms support software beamforming and plane-wave imaging with high PRF, the majority of current clinical ultrasound systems do not have the software beamforming capability, which presents a critical challenge for translating the 2-D shear-wave elastography technique from laboratory to clinical scanners. To address this challenge, this paper presents a time-aligned sequential tracking (TAST) method for shear-wave tracking on conventional ultrasound scanners. TAST takes advantage of the parallel beamforming capability of conventional systems and realizes high-PRF shear-wave tracking by sequentially firing tracking vectors and aligning shear wave data in the temporal direction. The comb-push ultrasound shear elastography (CUSE) technique was used to simultaneously produce multiple shear wave sources within the field-of-view (FOV) to enhance shear wave SNR and facilitate robust reconstructions of 2-D elasticity maps. TAST and CUSE were realized on a conventional ultrasound scanner. A phantom study showed that the shear-wave speed measurements from the conventional ultrasound scanner were in good agreement with the values measured from other 2-D shear wave imaging technologies. An inclusion phantom study showed that the conventional ultrasound scanner had comparable performance to a state-of-the-art shear-wave imaging system in terms of bias and precision in measuring different sized inclusions. Finally, in vivo case analysis of a breast with a malignant mass, and a liver from a healthy subject demonstrated the feasibility of using the conventional ultrasound scanner for in vivo 2-D shear-wave elastography. These promising results indicate that the proposed technique can enable the implementation of 2-D shear-wave elastography on conventional ultrasound scanners and potentially facilitate wider clinical applications with shear-wave elastography.

A Comparative Study of Medical Imaging Techniques

Abstract: Medical Imaging Techniques (MITs) are non-invasive methods for looking inside the body without opening up the body surgically. It used to assist diagnosis or treatment of different medical conditions. There are many medical imaging techniques; every technique has different risks and benefits. This paper presents a review of these techniques; concepts, advantages, disadvantages, and applications. The concerning techniques are; X-ray radiography, X-ray Computed Tomography (CT), Magnetic Resonance Imaging (MRI), ultrasonography, Elastography, optical imaging, Radionuclide imaging includes (Scintigraphy, Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT)), thermography, and Terahertz imaging. The concepts, benefits, risks and applications of these techniques will present with details. A comparison between these techniques from point of view, image quality (spatial resolution and contrast), safety (effect of ionizing radiation, and heating effect of radiation on the body), and system availability (real time information and cost) will present.

Non-invasive detection of liver fibrosis: MR imaging features vs. MR elastography

Abstract: Purpose To compare accuracy of morphological features of liver on MRI and liver stiffness with MR elastography (MRE) for detection of significant liver fibrosis and cirrhosis.

Phase-sensitive optical coherence elastography at 1.5 million A-Lines per second.

Abstract: Shear-wave imaging optical coherence elastography (SWI-OCE) is an emerging method for 3D quantitative assessment of tissue local mechanical properties based on imaging and analysis of elastic wave propagation. Current methods for SWI-OCE involve multiple temporal optical coherence tomography scans (M-mode) at different spatial locations across tissue surface (B- and C-modes). This requires an excitation for each measurement position leading to clinically unacceptable long acquisition times up to tens of minutes. In this Letter, we demonstrate, for the first time, noncontact true kilohertz frame-rate OCE by combining a Fourier domain mode-locked swept source laser with an A-scan rate of ∼1.5 MHz and a focused air-pulse as an elastic wave excitation source. The propagation of the elastic wave in the sample was imaged at a frame rate of ∼7.3 kHz. Therefore, to quantify the elastic wave propagation velocity in a single direction, only a single excitation was needed. This method was validated by quantifying the elasticity of tissue-mimicking agar phantoms as well as of a porcine cornea ex vivo at different intraocular pressures. The results demonstrate that this method can reduce the acquisition time of an elastogram to milliseconds.

Assessment of liver fibrosis with 2-D shear wave elastography in comparison to transient elastography and acoustic radiation force impulse imaging in patients with chronic liver disease.

Abstract: Two-dimensional shear wave elastography (2-D SWE) is an ultrasound-based elastography method integrated into a conventional ultrasound machine. It can evaluate larger regions of interest and, therefore, might be better at determining the overall fibrosis distribution. The aim of this prospective study was to compare 2-D SWE with the two best evaluated liver elastography methods, transient elastography and acoustic radiation force impulse (point SWE using acoustic radiation force impulse) imaging, in the same population group. The study included 132 patients with chronic hepatopathies, in which liver stiffness was evaluated using transient elastography, acoustic radiation force impulse imaging and 2-D SWE. The reference methods were liver biopsy for the assessment of liver fibrosis (n = 101) and magnetic resonance imaging/computed tomography for the diagnosis of liver cirrhosis (n = 31). No significant difference in diagnostic accuracy, assessed as the area under the receiver operating characteristic curve (AUROC), was found between the three elastography methods (2-D SWE, transient elastography, acoustic radiation force impulse imaging) for the diagnosis of significant and advanced fibrosis and liver cirrhosis in the “per protocol” (AUROCs for fibrosis stages ≥2: 0.90, 0.95 and 0.91; for fibrosis stage [F] ≥3: 0.93, 0.95 and 0.94; for F = 4: 0.92, 0.96 and 0.92) and “intention to diagnose” cohort (AUROCs for F ≥2: 0.87, 0.92 and 0.91; for F ≥3: 0.91, 0.93 and 0.94; for F = 4: 0.88, 0.90 and 0.89). Therefore, 2-D SWE, ARFI imaging and transient elastography seem to be comparably good methods for non-invasive assessment of liver fibrosis.

Reduced Patellar Tendon Elasticity with Aging: In Vivo Assessment by Shear Wave Elastography.

Abstract: How aging affects the elasticity of tendons has long been debated, partly because of the limited methods for in vivo evaluation, which differ vastly from those for in vitro animal studies. In this study, we tested the reliability of shear wave elastography (SWE) in the evaluation of patellar tendons and their change in elasticity with age. We recruited 62 healthy participants in three age groups: 20–30 years (group 1), 40–50 years (group 2) and 60–70 years (group 3). Shear wave velocity and elastic modulus were measured at the proximal, middle and distal areas of the patellar tendon. Reliability was excellent at the middle area and fair to good at both ends. Compared with the other groups, group 3 had significantly decreased elastic modulus and shear wave velocity values ( p ≤ 0.001 vs. group 1 or 2), with significant increased side-to-side differences. SWE may be valuable in detecting aging tendons before visible abnormalities are observed on B-mode ultrasonography.

Quantitative methods for reconstructing tissue biomechanical properties in optical coherence elastography: a comparison study

Abstract: We present a systematic analysis of the accuracy of five different methods for extracting the biomechanical properties of soft samples using optical coherence elastography (OCE). OCE is an emerging noninvasive technique, which allows assessment of biomechanical properties of tissues with micrometer spatial resolution. However, in order to accurately extract biomechanical properties from OCE measurements, application of a proper mechanical model is required. In this study, we utilize tissue-mimicking phantoms with controlled elastic properties and investigate the feasibilities of four available methods for reconstructing elasticity (Young's modulus) based on OCE measurements of an air-pulse induced elastic wave. The approaches are based on the shear wave equation (SWE), the surface wave equation (SuWE), Rayleigh-Lamb frequency equation (RLFE), and finite element method (FEM), Elasticity values were compared with uniaxial mechanical testing. The results show that the RLFE and the FEM are more robust in quantitatively assessing elasticity than the other simplified models. This study provides a foundation and reference for reconstructing the biomechanical properties of tissues from OCE data, which is important for the further development of noninvasive elastography methods.