Rotation elastogram: a novel method to visualize local rigid body rotation under quasi-static compression
01 Apr 2016-Proceedings of SPIE (International Society for Optics and Photonics)-Vol. 9790, pp 386-393
TL;DR: A spatial compounding approach is utilized and significantly-improved rotation elastogram is demonstrated using this technique, demonstrating the improvement in the lateral motion tracking accuracy and its effects on the quality of rotational elastograms.
Abstract: During manual palpation of breast masses, the perception of its stiffness and slipperiness are the two commonly used information by the physician. In order to reliably and quantitatively obtain this information several non-invasive elastography techniques have been developed that seek to provide an image of the underlying mechanical properties, mostly stiffness-related. Very few approaches have visualized the "slip" at the lesion-background boundary that only occurs for a loosely-bonded benign lesion. It has been shown that axial-shear strain distribution provides information about underlying slip. One such feature, referred to as "fill-in" was interpreted as a surrogate of the rotation undergone by an asymmetrically-oriented-loosely bonded-benign-lesion under quasi-static compression. However, imaging and direct visualization of the rotation itself has not been addressed yet. In order to accomplish this, the quality of lateral displacement estimation needs to be improved. In this simulation study, we utilize spatial compounding approach and assess the feasibility to obtain good quality rotation elastogram. The angular axial and lateral displacement estimates were obtained at different insonification angles from a phantom containing an elliptical inclusion oriented at 45°, subjected to 1% compression from the top. A multilevel 2D-block matching algorithm was used for displacement tracking and 2D-least square compounding of angular axial and lateral displacement estimates was employed. By varying the maximum steering angle and incremental angle, the improvement in the lateral motion tracking accuracy and its effects on the quality of rotational elastogram were evaluated. Results demonstrate significantly-improved rotation elastogram using this technique.
Citations
More filters
01 Jan 2012
TL;DR: In this article, the authors investigated the feasibility of using synthetic aperture (SA) imaging to accurately estimate the 2D displacement vector, thereby enhancing the performance of NIVE, and demonstrated that as few as eight transmit elements can generate strain elastograms with a minimal loss of image quality.
Abstract: The health of the carotid artery is an important
indicator of cardiovascular
disease (CVD). The advent of CVD
results in reduced elasticity and flexibility of the arterial wall.
These changes in elasticity can be measured using
non-invasive
vascular elastography (NIVE). Elastography is performed by
subjecting the tissue under investigation to a form of mechanical
excitation. The
resultant tissue displacement is measured and used
to compute the spatial variation of strain within the tissue. These
strain maps, known as elastograms,
serve as surrogates for tissue
elasticity. While elastography can be performed
with any imaging
modality, ultrasound is portable, inexpensive and has high
frame
rates, making it ideal for diagnostic screening purposes. However,
linear array based elastography can accurately estimate
displacement only in the
axial direction. Consequently, NIVE
cannot characterize strain across artery
cross-sections,
restricting the diagnostic value of this technique.
The objective
of this thesis was to investigate the feasibility of using
synthetic aperture (SA) imaging to accurately estimate the 2D
displacement vector, thereby enhancing the performance of NIVE. We
demonstrated, through
simulation and experiment, that SA imaging
can accurately measure both axial and lateral displacements. These
displacements generate high quality radial
and circumferential
strain elastograms of the arterial cross-section. Compared
to
conventional ultrasound elastography, SA elastography improved the
error
in lateral displacements and the resultant strain
elastograms by an order of
magnitude. However, the low frame rates
and large data volumes required by
SA imaging render this approach
clinically inviable. To overcome this limitation, we developed a
sparse array based elastography system. We demonstrated
that as
few as eight transmit elements can generate strain elastograms with
a
16x improvement in frame rate and data volume, at a minimal loss
of image
quality. The efficacy of sparse array elastography was
compared to that of
a compounded plane wave imaging system. It was
demonstrated that sparse
array imaging displayed higher lateral
sensitivity thereby producing strain elastograms with 20% improved
image quality.
From the success of this novel approach to
elastography, it was concluded
that further development and
integration on a commercial ultrasound system
would greatly
enhance clinical use.
3 citations
TL;DR: An experimental and numerical study of the rotation fill-in signature as a function of the probe's tilt angle is presented, arguing that the formulation of a tumor model with a bonding condition dependence may have potential implications in correct tumor classification.
Abstract: The rotation fill-in is a signature of tumor benignity in rotation elastograms and has been used for breast tumor classification. It is a consequence of the bonding condition at the tumor–tissue interface. In vivo studies have revealed the presence of fluctuations when inclined uniaxial external compression is applied. However, the physical meaning of these fluctuations is not yet fully understood. In this article we present an experimental and numerical study of the rotation fill-in signature as a function of the probe's tilt angle. This angle introduces asymmetries in the stress field, modifying the bonding condition. We numerically consider this asymmetry by using a model of friction with a simple angular dependence, which allows us to capture the experimental trends. We argue that the formulation of a tumor model with a bonding condition dependence may have potential implications in correct tumor classification.
References
More filters
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
"Rotation elastogram: a novel method..." refers background in this paper
...Among them, Quasi-static ultrasound elastography [8] is now available in many commercial clinical scanners, but thus far it has mostly exploited only the contrast due to the “stiffness” changes of the underlying tissue....
[...]
01 Jan 2013
2,533 citations
"Rotation elastogram: a novel method..." refers background or methods in this paper
...ωxy (rotation) = 1⁄2 ( ∂v ∂x − ∂u ∂y ) -----------[1]...
[...]
...Rotation can be given by the Equation [1] [10] as shown below...
[...]
...The rotation elastogram was computed from the displacement estimates using Equation [1] given earlier....
[...]
...This represents about 12% of all new cancer cases and 25% of all cancers in women [1] ....
[...]
TL;DR: Elastography has the potential to be useful in the evaluation of areas of shadowing on the sonogram and also may be helpful in the distinction of benign from malignant masses.
Abstract: PURPOSE: To determine the appearance of various breast lesions on elastograms and to explore the potential of elastography in the diagnosis of breast lesions. MATERIALS AND METHODS: A total of 46 breast lesions were examined with elastography. Patients underwent biopsy or aspiration of all lesions, revealing 15 fibroadenomas, 12 carcinomas, six fibrocystic nodules, and 13 other lesions. The elastogram was generated from radio-frequency data collected with use of a 5-MHz linear-array transducer. The elastogram and corresponding sonogram were evaluated by a single observer for lesion visualization, relative brightness, and margin definition and regularity. The sizes of the lesions at each imaging examination and at biopsy were recorded and compared. RESULTS: Softer tissues such as fat appear as bright areas on elastograms. Firm tissues, including parenchyma, cancers, and other masses, appear darker. The cancers were statistically significantly darker than fibroadenomas (P < .005) and substantially larger on...
980 citations
TL;DR: This review summarizes the fundamental principles, the timeline of developments in major categories of elastographic imaging, and concludes with recent results from clinical trials and forward-looking issues.
Abstract: After 20 years of innovation in techniques that specifically image the biomechanical properties of tissue, the evolution of elastographic imaging can be viewed from its infancy, through a proliferation of approaches to the problem to incorporation on research and then clinical imaging platforms. Ultimately this activity has culminated in clinical trials and improved care for patients. This remarkable progression represents a leading example of translational research that begins with fundamentals of science and engineering and progresses to needed improvements in diagnostic and monitoring capabilities applied to major categories of disease, surgery and interventional procedures. This review summarizes the fundamental principles, the timeline of developments in major categories of elastographic imaging, and concludes with recent results from clinical trials and forward-looking issues.
485 citations
"Rotation elastogram: a novel method..." refers background in this paper
...Quasi-static elastography, ARFI and Shear wave elastography are a few of them [12][19][20] ....
[...]
TL;DR: This paper presents a classification of elasticity measurement and imaging techniques based on the methods used for generating a stress in the tissue, and measurement of the tissue response and presents various techniques of EI.
Abstract: From times immemorial manual palpation served as a source of information on the state of soft tissues and allowed detection of various diseases accompanied by changes in tissue elasticity. During the last two decades, the ancient art of palpation gained new life due to numerous emerging elasticity imaging (EI) methods. Areas of applications of EI in medical diagnostics and treatment monitoring are steadily expanding. Elasticity imaging methods are emerging as commercial applications, a true testament to the progress and importance of the field.In this paper we present a brief history and theoretical basis of EI, describe various techniques of EI and, analyze their advantages and limitations, and overview main clinical applications. We present a classification of elasticity measurement and imaging techniques based on the methods used for generating a stress in the tissue (external mechanical force, internal ultrasound radiation force, or an internal endogenous force), and measurement of the tissue response. The measurement method can be performed using differing physical principles including magnetic resonance imaging (MRI), ultrasound imaging, X-ray imaging, optical and acoustic signals.Until recently, EI was largely a research method used by a few select institutions having the special equipment needed to perform the studies. Since 2005 however, increasing numbers of mainstream manufacturers have added EI to their ultrasound systems so that today the majority of manufacturers offer some sort of Elastography or tissue stiffness imaging on their clinical systems. Now it is safe to say that some sort of elasticity imaging may be performed on virtually all types of focal and diffuse disease. Most of the new applications are still in the early stages of research, but a few are becoming common applications in clinical practice.
370 citations
"Rotation elastogram: a novel method..." refers background in this paper
...Quasi-static elastography, ARFI and Shear wave elastography are a few of them [12][19][20] ....
[...]