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Myocardial strain imaging has been shown to add significant prognostic and diagnostic value to echocardiography. While the reliability of ultrasound-based strain measurement techniques has improved considerably in terms of regional consistency and inter-reader, inter-vendor agreement; most state-of-the-art strain imaging packages constrain their analyses to individual cardiac cycles. This limitation...
Single Track Location Shear Wave Elasticity Imaging (STL-SWEI) creates high resolution shear wave speed maps by comparing the tissue motion at each tracking location between spatially-offset radiation force excitations. While STL-SWEI circumvents the resolution-limiting effects of speckle noise, it requires a series of excitation-tracking ensembles to build up a lateral field of view, increasing the...
Harmonic imaging techniques are widely used in B-mode abdominal imaging and motion tracking in shear wave elasticity imaging (SWEI) to reduce clutter and improve data quality. Harmonic imaging can be both signal-to-noise (SNR) and penetration depth (PD) limited, resulting in decreased diagnostic utility. This work evaluates B-mode harmonic imaging and SWEI harmonic tracking data quality between imaging...
In conventional ultrasonic monitoring of high intensity focused ultrasound (HIFU) treatment, it has been difficult to track the target region when the tissue to be treated deviates from the imaging plane along the elevation axis of the 1-D probe. A 2-D phased array probe providing 3-D imaging capability requires a large number of elements and it is very expensive to build a system to drive all channels...
Time delay estimation using cross correlation between successive RF lines is an established method to estimate tissue velocity. We have applied this method on our system using 10 MHz transducers sutured to the epicardium to measure the myocardial contraction pattern at high spatial and temporal resolution. In this setup, the myocardial tissue velocity will generally increase with the depth, as the...
Fast acquisition sequences enable >200Hz 2D cardiac B-mode imaging with little compromise in image quality. Fast imaging minimizes frame to frame decorrelation, enabling radiofrequency (RF)-based tracking for enhanced signal-to-noise ratio (SNR) in motion and deformation imaging. Our objective was to compare the performance and clinical usefulness of Fast RF-based Tracking (FRFT) to the established...
Myocardial deformation imaging at a high frame rate (HFR) has the potential to gain new insights in cardiac mechanics by resolving short-lived mechanical events during the cardiac cycle. In order to achieve such high frame rate, our lab recently proposed to combine multi-line transmit with ‘anatomical imaging’ i.e. imaging only the anatomically relevant spatial domain (e.g. the myocardium). Although...
Cervical spine pathoanatomy is typically evaluated by static radiographs, CT or MRI; however, these modalities are unable to directly measure the dynamic performance of the spine that account for its functionality. We have developed an ultrasound based technique that provides a non-invasive, realtime, quantitative, textitin-vivo image of the C-spine that allows for assessment of the dynamic motion...
Sentinel lymph nodes (SLNs) are the first draining lymph nodes when metastatic cancer cells are spreading. Sentinel lymph node biopsy (SLNB), which is performed invasively, is the current standard treatment to determine whether the cancer cells are spreading or not. A non-invasive SLN imaging modality along with fine needle aspiration biopsy (FNAB) would be beneficial for staging the axillary lymph...
Ultrasound imaging is a real-time and high frame rate modality suitable for the analysis of tendon dynamics, e.g. for diagnosis of carpal tunnel syndrome. Tendon displacement quantification algorithms based on speckle tracking are sensitive to underestimation due to stationary clutter present in the tendon region. In this study we propose an improved speckle tracking method based on Singular Value...
Workers who are repeatedly exposed to high cyclic loading are at high risk for degenerative cervical spine disease. Standard methods to evaluate spine motion using optical tracking or dual fluoroscopy are impractical for imaging patients in the work environment. Portable ultrasound can image cervical spine kinematics in real time, and may be able to detect abnormal spine function not apparent by static...
Uterine peristaltic movement plays an important role for the success of embryo implantation. This is especially relevant in the context of assisted reproductive technology. Unfortunately, the lack of tools for quantitative analysis limits our understanding of the uterine contractility. Recently, strain analysis by ultrasound speckle tracking has gained attention for the assessment of the uterine contractility...
Uterine peristaltic movement plays an important role for the success of embryo implantation. This is especially relevant in the context of assistive reproduction technology. Unfortunately, the lack of tools for quantitative analysis limits our understanding of the uterine activity. Recently, strain analysis by ultrasound speckle tracking has gained attention for assessment of the uterine activity...
In epicardial ultrasound, the myocardial tissue velocity will generally increase with depth, as the endocardial tissue usually moves at higher velocity than the epicardial tissue. Higher velocity resolution is therefore required in the epicardial region, while a higher maximum detectable velocity is needed in the endocardial region. This study introduces a method to balance this requirement, processing...
Nonlinear shear waves have a cubic nonlinearity which generates a unique odd harmonic signature. This behavior was first observed in a homogeneous gelatin phantom with ultrafast plane wave compounding ultrasound imaging and correlation-based tracking algorithm that determines particle motion. However, in heterogeneous tissue, like brain, clutter degrades motion tracking and destroys the weak odd harmonics...
Carpal tunnel syndrome (CTS) is the most common wrist neuropathy. Ultrasound can image the tendons in real-time, enabling analysis of tendon dynamics. We earlier developed and validated a speckle tracking algorithm [1] using Normalized Cross Correlation (NCC) on a stationary region of interest (ROI) over the tendon path (Fig 1a). However, NCC is sensitive to clutter and shadows which lead to motion...
Recently multiple studies have demonstrated microbubble (MB)-based super-resolution imaging (SRI) with ∼λ/10 subwavelength resolution on mice and rats. Clinical translation of SRI, however, faces many technical challenges such as low signal-to-noise-ratio (SNR) of the MB signal and physiologic and operator-induced motion in humans. In this study, we take advantage of the rich spatiotemporal information...
Linearly polarized nonlinear shear waves have a cubic nonlinearity which generates shear shock waves. This behavior has been only observed in a homogeneous gelatin phantom with ultrafast plane wave ultrasound imaging and a correlation-based tracking algorithm to determine particle motion. However, in heterogeneous soft tissue, such as brain, clutter degrades motion tracking. We propose a high frame-rate...
To implement super-resolution imaging of microvessels in clinical practice, the trade-off between the concentration of microbubbles (MB) appropriate to detect single MB and reasonable short measurement times has to be resolved. Therefore, we estimated the measurement times necessary to adequately reconstruct the microvessel trees in 3 different tumor models.
Imaged-based motion analysis of human musculoskeletal systems is a burgeoning area of research. We have previously demonstrated the capability of B-mode ultrasound (US) to statically and dynamically image cervical spine kinematics both ex-vivo and in-vivo. However high frame rates and long exposure time are required to successfully track the displacement of contiguous spinal units over thousands of...
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