A novel fast full inversion based breast ultrasound elastography technique

Karimi, Hirad; Fenster, Aaron; Samani, Abbas

doi:10.1088/0031-9155/58/7/2219

Cited by 15 publications

(19 citation statements)

References 26 publications

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“…Consumers use different behavioral or physiological processes to achieve the appropriate balance of elements required for maintenance, growth and reproduction [23,24]. For instance, nutrient limitations might be addressed by increasing the feeding rate or selecting more nutritious patches of food [24,25]. According to stoichiometric regulation, digestion and absorption may also be adjusted to favor the retention of the most limiting element, and excess nutrients can be released by excretion or respiration [26].…”

Section: Introductionmentioning

confidence: 99%

“…According to stoichiometric regulation, digestion and absorption may also be adjusted to favor the retention of the most limiting element, and excess nutrients can be released by excretion or respiration [26]. Consequently, the extent to which individuals will be able to compensate for this imbalance will ultimately determine the constraints on an individual’s performance and survival as well as alterations in the consumers’ nutrient cycling [23,25]. …”

Section: Introductionmentioning

confidence: 99%

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Consequences of Warming and Resource Quality on the Stoichiometry and Nutrient Cycling of a Stream Shredder

2015

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As a result of climate change, streams are warming and their runoff has been decreasing in most temperate areas. These changes can affect consumers directly by increasing their metabolic rates and modifying their physiology and indirectly by changing the quality of the resources on which organisms depend. In this study, a common stream detritivore (Echinogammarus berilloni Catta) was reared at two temperatures (15 and 20°C) and fed Populus nigra L. leaves that had been conditioned either in an intermittent or permanent reach to evaluate the effects of resource quality and increased temperatures on detritivore performance, stoichiometry and nutrient cycling. The lower quality (i.e., lower protein, soluble carbohydrates and higher C:P and N:P ratios) of leaves conditioned in pools resulted in compensatory feeding and lower nutrient retention capacity by E. berilloni. This effect was especially marked for phosphorus, which was unexpected based on predictions of ecological stoichiometry. When individuals were fed pool-conditioned leaves at warmer temperatures, their growth rates were higher, but consumers exhibited less efficient assimilation and higher mortality. Furthermore, the shifts to lower C:P ratios and higher lipid concentrations in shredder body tissues suggest that structural molecules such as phospholipids are preserved over other energetic C-rich macromolecules such as carbohydrates. These effects on consumer physiology and metabolism were further translated into feces and excreta nutrient ratios. Overall, our results show that the effects of reduced leaf quality on detritivore nutrient retention were more severe at higher temperatures because the shredders were not able to offset their increased metabolism with increased consumption or more efficient digestion when fed pool-conditioned leaves. Consequently, the synergistic effects of impaired food quality and increased temperatures might not only affect the physiology and survival of detritivores but also extend to other trophic compartments through detritivore-mediated nutrient cycling.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Consequences of Warming and Resource Quality on the Stoichiometry and Nutrient Cycling of a Stream Shredder

2015

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“…The boundary conditions currently used in the iterative inversion schemes include displacement boundary conditions [13, 25], force boundary conditions [8] and a combination of both [16, 20, 23]. However, the force distribution within the tissue is difficult to measure in vivo [7].…”

Section: Discussionmentioning

confidence: 99%

“…However, the force distribution within the tissue is difficult to measure in vivo [7]. The combination boundary conditions of displacement and force need special experimental setup [20, 23], and hence limit the usage in the clinic. The boundary condition used in the proposed method is the modulus boundary condition which assumes the moduli of the boundary elements around the reconstruction ROI are the same [13, 15, 44].…”

Section: Discussionmentioning

confidence: 99%

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A regularization-free elasticity reconstruction method for ultrasound elastography with freehand scan

et al. 2014

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BackgroundIn ultrasound elastography, reconstruction of tissue elasticity (e.g., Young’s modulus) requires regularization and known information of forces and/or displacements on tissue boundaries. In practice, it is challenging to choose an appropriate regularization parameter; and the boundary conditions are difficult to obtain in vivo. The purpose of this study is to develop a more applicable algorithm that does not need any regularization or boundary force/displacement information.MethodsThe proposed method adopts the bicubic B-spline as the tissue motion model to estimate the displacement fields. Then the estimated displacements are input to the finite element inversion scheme to reconstruct the Young’s modulus of each element. In the inversion, a modulus boundary condition is used instead of force/displacement boundary conditions. Simulation and experiments on tissue-mimicking phantoms are carried out to test the proposed method.ResultsThe simulation results demonstrate that Young’s modulus reconstruction of the proposed method has a relative error of −3.43 ± 0.43% and root-squared-mean error of 16.94 ± 0.25%. The phantom experimental results show that the target hardening artifacts in the strain images are significantly reduced in the Young’s modulus images. In both simulation and phantom studies, the size and position of inclusions can be accurately depicted in the modulus images.ConclusionsThe proposed method can reconstruct tissue Young’s modulus distribution with a high accuracy. It can reduce the artifacts shown in the strain image and correctly delineate the locations and sizes of inclusions. Unlike most modulus reconstruction methods, it does not need any regularization during the inversion procedure. Furthermore, it does not need to measure the boundary conditions of displacement or force. Thus this method can be used with a freehand scan, which facilitates its usage in the clinic.

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A novel tissue mechanics‐based method for improved motion tracking in quasi‐static ultrasound elastography

et al. 2022

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Purpose Most cancers are associated with biological and structural changes that lead to tissue stiffening. Therefore, imaging tissue stiffness using quasi‐static ultrasound elastography (USE) can potentially be effective in cancer diagnosis. USE techniques developed for stiffness image reconstruction use noisy displacement data to obtain the stiffness images. In this study, we propose a technique to substantially improve the accuracy of the displacement data computed through ultrasound tissue motion tracking techniques, especially in the lateral direction. Methods The proposed technique uses mathematical constraints derived from fundamental tissue mechanics principles to regularize displacement and strain fields obtained using Global Ultrasound Elastography (GLUE) and Second‐Order Ultrasound Elastography (SOUL) methods. The principles include a novel technique to enforce (1) tissue incompressibility using 3D Boussinesq model and (2) deformation compatibility using the compatibility differential equation. The technique was validated thoroughly using metrics pertaining to Signal‐to‐Noise‐Ratio (SNR), Contrast‐to‐Noise‐Ratio (CNR) and Normalized Cross Correlation (NCC) for four tissue‐mimicking phantom models and two clinical breast ultrasound elastography cases. Results The results show substantial improvement in the displacement and strain images generated using the proposed technique. The tissue‐mimicking phantom study results indicate that the proposed method is superior in improving image quality compared to the GLUE and SOUL techniques as it shows an average axial strain SNR and CNR improvement of 44% and 63%, and lateral strain SNR and CNR improvement of 130% and 435%, respectively. The results of the phantom study also indicate higher accuracy of displacement images obtained using the proposed technique, including improvement ranges of 7–84% and 26–140% for axial and lateral displacement images, respectively. For the clinical cases, the results indicate average improvement of 48% and 64% in SNR and CNR, respectively, in the axial strain images, and average improvement of 40% and 41% in SNR and CNR, respectively, in the lateral strain images. Conclusion The proposed method is very effective in producing improved estimate of tissue displacement and strain images, especially with the lateral displacement and strain where the improvement is highly remarkable. While the method shows promise for clinical applications, further investigation is necessary for rigorous assessment of the method's performance in the clinic.

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A novel fast full inversion based breast ultrasound elastography technique

Cited by 15 publications

References 26 publications

Consequences of Warming and Resource Quality on the Stoichiometry and Nutrient Cycling of a Stream Shredder

Consequences of Warming and Resource Quality on the Stoichiometry and Nutrient Cycling of a Stream Shredder

A regularization-free elasticity reconstruction method for ultrasound elastography with freehand scan

A novel tissue mechanics‐based method for improved motion tracking in quasi‐static ultrasound elastography

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