Prototype of a low-cost 3D breast ultrasound imaging system

This work describes a setup of the new acquisition system for 3D ultrasound images (i.e. B-mode) for breast tomography. Since premature and precise breast lesions diagnoses turn out in treatment more efficient and save lives, we are looking for a more precise, less painful exams and dose reduction for the patient. Therefore, a low cost scanner mechanism was built aiming to accommodate breasts under water while patient is laid down on a bed in which a robotic arm guides the ultrasound probe to acquire 2D images. Then 3D image is reconstructed using the 2D images due to render the mammary volume searching for lesions. The low cost scanner was built using a regular ultrasound machine, linear probe and major controls made by an Arduino Uno. We compared the acquired phantom images with gold standard images for mammary tissues diagnostics, i.e. Computerized Tomography and Magnetic Resonance Images. This study was evaluated using a paraffin-gel and mineral oil control phantom. Results show that the provided module is convicting enough to be used in local hospital as the next step of this study

Ultrasound image based human gallbladder 3D modelling along with volume and stress level assessment

Purpose: Three-dimensional (3D) gallbladder (GB) geometrical models are essential to GB motor function evaluation and GB wall biomechanical property identification by employing finite element analysis (FEA) in GB disease diagnosis with ultrasound systems. Methods for establishing such 3D geometrical models based on static two-dimensional (2D) ultrasound images scanned along the long-axis/sagittal and short-axis/transverse cross-sections in routine GB disease diagnosis at the beginning of emptying phase have not been documented in the literature so far. Methods: Based on two custom MATLAB codes composed, two images were segmented manually to secure two sets of the scattered points for the long- and short-axis GB cross-section edges; and the points were best fitted with a piecewise cubic spline function, and the short-axis cross-section edges were lofted along the long-axis to yield a 3D geometrical model, then GB volume of the model was figured out. The model was read into SolidWorks for real surface generation and involved in ABAQUS for FEA. Results: 3D geometrical models of seven typical GB samples were established. Their GB volumes are with 15.5% and − 4.4% mean errors in comparison with those estimated with the ellipsoid model and sum-of-cylinders method but can be correlated to the latter very well. The maximum first principal in-plane stress in the 3D models is higher than in the ellipsoid model by a factor of 1.76. Conclusions: A numerical method was put forward here to create 3D GB geometrical models and can be applied to GB disease diagnosis and GB shape analysis with principal component method potentially in the future

Micromachined Scanning Devices for 3D Acoustic Imaging

Acoustic imaging (including ultrasound and photoacoustic imaging) refers to a class of imaging methods that use high-frequency sound (ultrasound) waves to generate contrast images for the interrogated media. It provides 3D spatial distribution of structural, mechanical, and even compositional properties in different materials. To conduct 3D ultrasound imaging, 2D ultrasound transducer arrays followed by multi-channel high-frequency data acquisition (DAQ) systems are frequently used. However, as the quantity and density of the transducer elements and also the DAQ channels increase, the acoustic imaging system becomes complex, bulky, expensive, and also power consuming. This situation is especially true for 3D imaging systems, where a 2D transducer array with hundreds or even thousands of elements could be involved. To address this issue, the objective of this research is to achieve new micromachined scanning devices to enable fast and versatile 2D ultrasound signal acquisition for 3D image reconstruction without involving complex physical transducer arrays and DAQ electronics. The new micromachined scanning devices studied in this research include 1) a water-immersible scanning mirror microsystem, 2) a micromechanical scanning transducer, and 3) a multi-layer linear transducer array. Especially, the water-immersible scanning mirror microsystem is capable of scanning focused ultrasound beam (from a single-element transducer) in two dimensions for 3D high-resolution acoustic microscopy. The micromechanical scanning transducer is capable of sending and receiving ultrasound signal from a single-element transducer to a 2D array of locations for 3D acoustic tomography. The multi-layer linear transducer array allows a unique electronic scanning scheme to simulate the functioning of a much larger 2D transducer array for 3D acoustic tomography. The design, fabrication and testing of the above three devices have been successfully accomplished and their applications in 3D acoustic microscopy and tomography have been demonstrated

Micromachined Scanning Devices for 3D Acoustic Imaging

Acoustic imaging (including ultrasound and photoacoustic imaging) refers to a class of imaging methods that use high-frequency sound (ultrasound) waves to generate contrast images for the interrogated media. It provides 3D spatial distribution of structural, mechanical, and even compositional properties in different materials. To conduct 3D ultrasound imaging, 2D ultrasound transducer arrays followed by multi-channel high-frequency data acquisition (DAQ) systems are frequently used. However, as the quantity and density of the transducer elements and also the DAQ channels increase, the acoustic imaging system becomes complex, bulky, expensive, and also power consuming. This situation is especially true for 3D imaging systems, where a 2D transducer array with hundreds or even thousands of elements could be involved. To address this issue, the objective of this research is to achieve new micromachined scanning devices to enable fast and versatile 2D ultrasound signal acquisition for 3D image reconstruction without involving complex physical transducer arrays and DAQ electronics. The new micromachined scanning devices studied in this research include 1) a water-immersible scanning mirror microsystem, 2) a micromechanical scanning transducer, and 3) a multi-layer linear transducer array. Especially, the water-immersible scanning mirror microsystem is capable of scanning focused ultrasound beam (from a single-element transducer) in two dimensions for 3D high-resolution acoustic microscopy. The micromechanical scanning transducer is capable of sending and receiving ultrasound signal from a single-element transducer to a 2D array of locations for 3D acoustic tomography. The multi-layer linear transducer array allows a unique electronic scanning scheme to simulate the functioning of a much larger 2D transducer array for 3D acoustic tomography. The design, fabrication and testing of the above three devices have been successfully accomplished and their applications in 3D acoustic microscopy and tomography have been demonstrated

超音波スペックルトラッキングによる高解像度血管イメージングの研究

Tohoku University梅村晋一郎課

Computer-assisted motion compensation and analysis of perfusion ultrasound data

Magdeburg, Univ., Fak. für Informatik, Diss., 2014von Sebastian Schäfe

Non-invasive ultrasound monitoring of regional carotid wall structure and deformation in atherosclerosis

Thesis (Ph. D.)--Harvard--Massachusetts Institute of Technology Division of Health Sciences and Technology, 2001.Includes bibliographical references (p. 223-242).Atherosclerosis is characterized by local remodeling of arterial structure and distensibility. Developing lesions either progress gradually to compromise tissue perfusion or rupture suddenly to cause catastrophic myocardial infarction or stroke. Reliable measurement of changes in arterial structure and composition is required for assessment of disease progression. Non-invasive carotid ultrasound can image the heterogeneity of wall structure and distensibility caused by atherosclerosis. However, this capability has not been utilized for clinical monitoring because of speckle noise and other artifacts. Clinical measures focus instead on average wall thickness and diameter distension in the distal common carotid to reduce sensitivity to noise. The goal of our research was to develop an effective system for reliable regional structure and deformation measurements since these are more sensitive indicators of disease progression. We constructed a system for freehand ultrasound scanning based on custom software which simultaneously acquires real-time image sequences and 3D frame localization data from an electromagnetic spatial localizer. With finite element modeling, we evaluated candidate measures of regional wall deformation.(cont.) Finally, we developed a multi-step scheme for robust estimation of local wall structure and deformation. This new strategy is based on a directionally-sensitive segmentation functional and a motion-region-of-interest constrained optical flow algorithm. We validated this estimator with simulated images and clinical ultrasound data. The results show structure estimates that are accurate and precise, with inter- and intra-observer reproducibility surpassing existing methods. Estimates of wall velocity and deformation likewise show good overall accuracy and precision. We present results from a proof-of-principle evaluation conducted in a pilot study of normal subjects and clinical patients. For one example, we demonstrate the combination of 2D image processing with 3D frame localization for visualization of the carotid volume. With slice localization, estimates of carotid wall structure and deformation can be derived for all axial positions along the carotid artery. The elements developed here provide the tools necessary for reliable quantification of regional wall structure and composition changes which result from atherosclerosis.by Raymond C. Chan.Ph.D

Automated Analysis of 3D Stress Echocardiography

__Abstract__ The human circulatory system consists of the heart, blood, arteries, veins and capillaries. The heart is the muscular organ which pumps the blood through the human body (Fig. 1.1,1.2). Deoxygenated blood flows through the right atrium into the right ventricle, which pumps the blood into the pulmonary arteries. The blood is carried to the lungs, where it passes through a capillary network that enables the release of carbon dioxide and the uptake of oxygen. Oxygenated blood then returns to the heart via the pulmonary veins and flows from the left atrium into the left ventricle. The left ventricle then pumps the blood through the aorta, the major artery which supplies blood to the rest of the body [Drake et a!., 2005; Guyton and Halt 1996]. Therefore, it is vital that the cardiovascular system remains healthy. Disease of the cardiovascular system, if untreated, ultimately leads to the failure of other organs and death

Post formation processing of cardiac ultrasound data for enhancing image quality and diagnostic value

Cardiovascular diseases (CVDs) constitute a leading cause of death, including premature death, in the developed world. The early diagnosis and treatment of CVDs is therefore of great importance. Modern imaging modalities enable the quantification and analysis of the cardiovascular system and provide researchers and clinicians with valuable tools for the diagnosis and treatment of CVDs. In particular, echocardiography offers a number of advantages, compared to other imaging modalities, making it a prevalent tool for assessing cardiac morphology and function. However, cardiac ultrasound images can suffer from a range of artifacts reducing their image quality and diagnostic value. As a result, there is great interest in the development of processing techniques that address such limitations. This thesis introduces and quantitatively evaluates four methods that enhance clinical cardiac ultrasound data by utilising information which until now has been predominantly disregarded. All methods introduced in this thesis utilise multiple partially uncorrelated instances of a cardiac cycle in order to acquire the information required to suppress or enhance certain image features. No filtering out of information is performed at any stage throughout the processing. This constitutes the main differentiation to previous data enhancement approaches which tend to filter out information based on some static or adaptive selection criteria. The first two image enhancement methods utilise spatial averaging of partially uncorrelated data acquired through a single acoustic window. More precisely, Temporal Compounding enhances cardiac ultrasound data by averaging partially uncorrelated instances of the imaged structure acquired over a number of consecutive cardiac cycles. An extension to the notion of spatial compounding of cardiac ultrasound data is 3D-to-2D Compounding, which presents a novel image enhancement method by acquiring and compounding spatially adjacent (along the elevation plane), partially uncorrelated, 2D slices of the heart extracted as a thin angular sub-sector of a volumetric pyramid scan. Data enhancement introduced by both approaches includes the substantial suppression of tissue speckle and cavity noise. Furthermore, by averaging decorrelated instances of the same cardiac structure, both compounding methods can enhance tissue structures, which are masked out by high levels of noise and shadowing, increasing their corresponding tissue/cavity detectability. The third novel data enhancement approach, referred as Dynamic Histogram Based Intensity Mapping (DHBIM), investigates the temporal variations within image histograms of consecutive frames in order to (i) identify any unutilised/underutilised intensity levels and (ii) derive the tissue/cavity intensity threshold within the processed frame sequence. Piecewise intensity mapping is then used to enhance cardiac ultrasound data. DHBIM introduces cavity noise suppression, enhancement of tissue speckle information as well as considerable increase in tissue/cavity contrast and detectability. A data acquisition and analysis protocol for integrating the dynamic intensity mapping along with spatial compounding methods is also investigated. The linear integration of DHBIM and Temporal Compounding forms the fourth and final implemented method, which is also quantitatively assessed. By taking advantage of the benefits and compensating for the limitations of each individual method, the integrated method suppresses cavity noise and tissue speckle while enhancing tissue/cavity contrast as well as the delineation of cardiac tissue boundaries even when heavily corrupted by cardiac ultrasound artifacts. Finally, a novel protocol for the quantitative assessment of the effect of each data enhancement method on image quality and diagnostic value is employed. This enables the quantitative evaluation of each method as well as the comparison between individual methods using clinical data from 32 patients. Image quality is assessed using a range of quantitative measures such as signal-to-noise ratio, tissue/cavity contrast and detectability index. Diagnostic value is assessed through variations in the repeatability level of routine clinical measurements performed on patient cardiac ultrasound scans by two experienced echocardiographers. Commonly used clinical measures such as the wall thickness of the Interventricular Septum (IVS) and the Left Ventricle Posterior Wall (LVPW) as well as the cavity diameter of the Left Ventricle (LVID) and Left Atrium (LAD) are employed for assessing diagnostic value

Characterising pattern asymmetry in pigmented skin lesions

Abstract. In clinical diagnosis of pigmented skin lesions asymmetric pigmentation is often indicative of melanoma. This paper describes a method and measures for characterizing lesion symmetry. The estimate of mirror symmetry is computed first for a number of axes at different degrees of rotation with respect to the lesion centre. The statistics of these estimates are the used to assess the overall symmetry. The method is applied to three different lesion representations showing the overall pigmentation, the pigmentation pattern, and the pattern of dermal melanin. The best measure is a 100% sensitive and 96% specific indicator of melanoma on a test set of 33 lesions, with a separate training set consisting of 66 lesions