Development of a training phantom for compression breast elastography-comparison of various elastography systems and numerical simulations.
01 Oct 2015-Journal of medical imaging (International Society for Optics and Photonics)-Vol. 2, Iss: 4, pp 047002-047002
TL;DR: A tissue-like agar-based phantom is developed, which mimics breast tissue with common abnormal lesions like fibroadenoma and invasive ductal carcinoma in a clinically perceived way and compares the sonographic and elastographic appearances using different commercially available systems.
Abstract: The elastic properties of tissue are related to tissue composition and pathological changes. It has been observed that many pathological processes increase the elastic modulus of soft tissue compared to normal. Ultrasound compression elastography is a method of characterization of elastic properties that has been the focus of many research efforts in the last two decades. In medical radiology, compression elastography is provided as an additional tool with ultrasound B-mode in the existing scanners, and the combined features of elastography and echography act as a promising diagnostic method in breast cancer detection. However, the full capability of the ultrasound elastography technique together with B-mode has not been utilized by novice radiologists due to the nonavailability of suitable, appropriately designed tissue-mimicking phantoms. Since different commercially available ultrasound elastographic scanners follow their own unique protocols, training novice radiologists is becoming cumbersome. The main focus of this work is to develop a tissue-like agar-based phantom, which mimics breast tissue with common abnormal lesions like fibroadenoma and invasive ductal carcinoma in a clinically perceived way and compares the sonographic and elastographic appearances using different commercially available systems. In addition, the developed phantoms are simulated using the finite-element method, and ideal strain images are generated. Strain images from experiment and simulation are compared based on image contrast parameters, namely contrast transfer efficiency (CTE) and observed strain, and they are in good agreement. The strain image contrast of malignant inclusions is significantly improved compared to benign inclusions, and the trend of CTE is similar for all elastographic scanners under investigation.
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TL;DR: SBH-PACT clearly reveals tumors by observing higher blood vessel densities associated with tumors at high spatial resolution, showing early promise for high sensitivity in radiographically dense breasts.
Abstract: We have developed a single-breath-hold photoacoustic computed tomography (SBH-PACT) system to reveal detailed angiographic structures in human breasts. SBH-PACT features a deep penetration depth (4 cm in vivo) with high spatial and temporal resolutions (255 µm in-plane resolution and a 10 Hz 2D frame rate). By scanning the entire breast within a single breath hold (~15 s), a volumetric image can be acquired and subsequently reconstructed utilizing 3D back-projection with negligible breathing-induced motion artifacts. SBH-PACT clearly reveals tumors by observing higher blood vessel densities associated with tumors at high spatial resolution, showing early promise for high sensitivity in radiographically dense breasts. In addition to blood vessel imaging, the high imaging speed enables dynamic studies, such as photoacoustic elastography, which identifies tumors by showing less compliance. We imaged breast cancer patients with breast sizes ranging from B cup to DD cup, and skin pigmentations ranging from light to dark. SBH-PACT identified all the tumors without resorting to ionizing radiation or exogenous contrast, posing no health risks.
290 citations
TL;DR: In this paper, a quasi-conical log-spiral antenna for homogeneous illumination over a large field was proposed, which produced not only an electric field with a circular polarization but also a homogenous illumination area with a 10 cm diameter.
Abstract: Conventional helical and horn antennas based on frequency selective surfaces have been used to provide microwave illumination in microwave-induced thermoacoustic tomography (TAT). However, the electromagnetic waves radiated from the conventional antennas are not circularly polarized and thus impair image quality. In addition, conventional antennas can provide uniform radiations only within a relatively small area and thus limit their clinical applications (e.g., breast imaging). To address these problems, we propose a quasi-conical log-spiral antenna for homogenous illumination over a large field. We theoretically and experimentally validated this approach. Tissue-mimicking phantoms were imaged. The antenna produced not only an electric field with a circular polarization but also a homogeneous illumination area with a 10 cm diameter. Accordingly, our method has advanced TAT by improving microwave illumination.
12 citations
12 Aug 2019
TL;DR: In this article, a new method for obtaining information about the stress-related properties of the cerebral vessel walls in vivo is described based on compression elastography and endoscopic optical coherence tomography.
Abstract: A new method for obtaining information about the stress-related properties of the cerebral vessel walls in vivo is described. The method is based on compression elastography and endoscopic optical coherence tomography. A pulse wave is used as a deforming force with a minimal risk of the vessel wall rupture under investigation. Evaluation of the object’s deformation is made using test points displacement. New approaches to multilayered tissue like phantoms of blood vessels construction and studies of pulsating flows of biological fluids in them are described. Experimental results of stress-related properties evaluation of the blood vessel walls are presented using tissue like phantoms.
8 citations
03 Jun 2019
TL;DR: In this article, the longitudinal elasticity modulus evaluation for the large blood vessel wall is presented based on obtaining and computer analyzing structural images of the same section of the investigated blood vessel, at the moments correspondences to systole and diastole.
Abstract: The method of longitudinal elasticity modulus evaluation for the large blood vessel wall is presented. It is based on obtaining and computer analyzing structural images of the same section of the investigated blood vessel wall at the moments correspondent to systole and diastole. Endoscopic optical coherence tomography system with a forward-side probe was used by the structural images raw data acquisition. Digital analysis of structural images includes noise reduction, detection of control points, combination them together and calculation of relative displacements. The Young's modulus was calculated taking into account the surface area of the scanning region, the coherence probing depth and the magnitude of the deformation impact of the pulse wave.
6 citations
TL;DR: The proposed hardware setup and image reconstruction was capable of identifying simulated tumors in the breast phantom and real tumor in vivo studies and the precision in volume estimation of the tumor in the control phantom was 96.89%.
Abstract: It has been proven that early breast cancer diagnosis increases the success rate of treatment. Thus, annual mammography exam is recommended for women over forty which is relatively expensive, painful, and the safety of the used radiation dose is still debated. In this work, we introduced an automatic, low cost, and less painful exam to pre-diagnose the tumors of the breast. The proposed imaging acquisition system uses a diagnostic ultrasound machine in B-mode, a linear probe, and a dedicated arm fixed below a bed in which all are controlled by a microcontroller. The breast is scanned underwater while patient is laid down on a bed in which the robotic arm guides the probe rotating to acquire a stack of 2D images. Then, we reconstructed the 3D image due to render the mammary volume, search for tumors, estimating the position, and volume size of them. We tuned and evaluated the imaging system using a control phantom made of paraffin-gel wax and deionized water, and a realistic breast phantom (Gphantom model), including eleven inclusions mimicking breast tumors. In addition, we scanned the phantoms by MRI and CT to evaluate the proposed method. Also, we scanned the breast of three invited volunteers and compared the results to their prior medical reports. The precision in volume estimation of the tumor in the control phantom was 96.89%. The proposed hardware setup and image reconstruction was capable of identifying simulated tumors in the breast phantom and real tumor in vivo studies.
3 citations
References
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TL;DR: Initial results of several phantom and excised animal tissue experiments are reported which demonstrate the ability of this technique to quantitatively image strain and elastic modulus distributions with good resolution, sensitivity and with diminished speckle.
3,636 citations
"Development of a training phantom f..." refers background or methods in this paper
...The elastic properties are imaged by giving a mechanical compression to tissues of interest and analyzing the response of the same, which is known as stiffness imaging or elastography.(5) The tissue response could be measured using either ultrasound,(5) MRI,(6) or optical methods....
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...Here, we focus on ultrasound elastography imaging techniques in which tissue displacement is estimated by finding out the time delay between reflected echoes.(5) Based on the compression, there are two different approaches in ultrasound elastography, namely compression or strain elastography(5) and shear wave elastography (SWE)....
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...In the literature, the promising features of compression elastography, namely strain and the area ratio between the ultrasound B-mode and elastogram, have been discussed toward improving the specificity of breast diagnosis.(5,11) The classification accuracy of the diagnostic system was significantly improved by including strain information as an additional input with ultrasound B-mode features....
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...isotropic behavior and, therefore, characterized by its Young’s modulus.(4,5) Now, the model became a discrete deformation problem whose solution is approximated to the solution obtained at the nodes of the mesh, which approximates the tissue continuous domain using FEM....
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...Since the applied compression is usually <5%, the tissue is assumed as a linear elastic material.(4,5,24) The results from the image analysis of developed phantoms indicate that malignant lesions (high-contrast lesions) have an improved conspicuity relative to low contrast, benign lesions using ultrasound compression elastography....
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TL;DR: The first in vivo investigations made on healthy volunteers emphasize the potential clinical applicability of SSI for breast cancer detection and results validating SSI in heterogeneous phantoms are presented.
Abstract: Supersonic shear imaging (SSI) is a new ultrasound-based technique for real-time visualization of soft tissue viscoelastic properties. Using ultrasonic focused beams, it is possible to remotely generate mechanical vibration sources radiating low-frequency, shear waves inside tissues. Relying on this concept, SSI proposes to create such a source and make it move at a supersonic speed. In analogy with the "sonic boom" created by a supersonic aircraft, the resulting shear waves will interfere constructively along a Mach cone, creating two intense plane shear waves. These waves propagate through the medium and are progressively distorted by tissue heterogeneities. An ultrafast scanner prototype is able to both generate this supersonic source and image (5000 frames/s) the propagation of the resulting shear waves. Using inversion algorithms, the shear elasticity of medium can be mapped quantitatively from this propagation movie. The SSI enables tissue elasticity mapping in less than 20 ms, even in strongly viscous medium like breast. Modalities such as shear compounding are implementable by tilting shear waves in different directions and improving the elasticity estimation. Results validating SSI in heterogeneous phantoms are presented. The first in vivo investigations made on healthy volunteers emphasize the potential clinical applicability of SSI for breast cancer detection.
2,300 citations
TL;DR: The results indicate that displacement patterns corresponding to cyclic displacements smaller than 200 nanometers can be measured and suggest the feasibility of a medical imaging technique for delineating elasticity and other mechanical properties of tissue.
Abstract: A nuclear magnetic resonance imaging (MRI) method is presented for quantitatively mapping the physical response of a material to harmonic mechanical excitation. The resulting images allow calculation of regional mechanical properties. Measurements of shear modulus obtained with the MRI technique in gel materials correlate with independent measurements of static shear modulus. The results indicate that displacement patterns corresponding to cyclic displacements smaller than 200 nanometers can be measured. The findings suggest the feasibility of a medical imaging technique for delineating elasticity and other mechanical properties of tissue.
2,015 citations
TL;DR: To evaluate the dynamic range of tissue imaged by elastography, the mechanical behavior of breast and prostate tissue samples subject to compression loading has been investigated and the data show that breast fat tissue has a constant modulus over the strain range tested while the other tissues have a modulus that is dependent on the strain level.
1,698 citations
"Development of a training phantom f..." refers background in this paper
...However, the Young’s modulus values of the targets are within a limited range for determining the elasticity contrast study, which is far less than the full dynamic range encountered during clinical scanning of breast tissue (25 to 550 kPa).(3) Most of the studies reported in literature to explain commercial phantoms discuss the axial and lateral resolutions, and do not discuss clinical performance....
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...Researchers have shown that the disease process in the human body alters the elastic properties of soft tissues.(3,4) The elastic properties are imaged by giving a mechanical compression to tissues of interest and analyzing the response of the same, which is known as stiffness imaging or elastography....
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...2)—which covers the entire range of breast abnormalities.(3) Additionally, simple cysts of various diameters were also mimicked to understand their elastographic appearance....
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TL;DR: Sonography can be used to accurately classify some solid lesions as benign, allowing imaging follow-up rather than biopsy, and this distinction could be definite enough to obviate biopsy.
Abstract: PURPOSE: To determine whether sonography could help accurately distinguish benign solid breast nodules from indeterminate or malignant nodules and whether this distinction could be definite enough to obviate biopsy. MATERIALS AND METHODS: Seven hundred fifty sonographically solid breast nodules were prospectively classified as benign, indeterminate, or malignant. Benign nodules had no malignant characteristics and had either intense homogeneous hyperechogenicity or a thin echogenic pseudocapsule with an ellipsoid shape or fewer than four gentle lobulations. Sonographic classifications were compared with biopsy results. The sensitivity, specificity, and negative and positive predictive values of the classifications were calculated. RESULTS: Benign histologic features were found in 625 (83%) lesions; malignant histologic features, in 125 (17%). Of benign lesions, 424 had been prospectively classified as benign. Two lesions classified as benign were found to be malignant at biopsy. Thus, the classification s...
1,683 citations
"Development of a training phantom f..." refers background in this paper
...reaction around the lesion, calcifications, microlobulation, and significant vascularization.(29) Out of the above-men-...
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