Optimization of Ultrasound Backscatter Spectroscopy to Assess Neurotoxic Effects of Anesthesia in the Newborn Non-human Primate Brain

Castañeda‐Martinez, Laura; Noguchi, Kevin K.; Ikonomidou, Chrysanthy; Zagzebski, James A.; Hall, Timothy J.; Rosado-Méndez, Iván M.

doi:10.1016/j.ultrasmedbio.2020.04.004

Cited by 2 publications

(4 citation statements)

References 75 publications

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“…Furthermore, the rejection of a large number of data is common in the initial steps of the development of quantitative imaging. For example, Castañeda-Martinez et al [53] rejected data from 11 out of 16 subjects while implementing Ultrasound Backscatter Spectroscopy in the neonatal brain. Also, Wang et al [54] rejected 50% of measurements when using shear wave elasticity imaging in the liver.…”

Section: Discussionmentioning

confidence: 99%

Shear Wave Dispersion as a Potential Biomarker for Cervical Remodeling During Pregnancy: Evidence From a Non-Human Primate Model

et al. 2021

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Shear wave dispersion (variation of phase velocity with frequency) occurs in tissues with layered and anisotropic microstructure and viscous components, such as the uterine cervix. This phenomenon, mostly overlooked in previous applications of cervical Shear Wave Elasticity Imaging (SWEI) for preterm birth risk assessment, is expected to change drastically during pregnancy due to cervical remodeling. Here we demonstrate the potential of SWEI-based descriptors of dispersion as potential biomarkers for cervical remodeling during pregnancy. First, we performed a simulation-based pre-selection of two SWEI-based dispersion descriptors: the ratio R of group velocities computed with particle-velocity and particle-displacement, and the slope S of the phase velocity vs. frequency. The pre-selection consisted of comparing the contrast-to-noise ratio (CNR) of dispersion descriptors in materials with different degrees of dispersion with respect to a low-dispersive medium. Shear waves induced in these media by SWEI were simulated with a finite-element model of Zener viscoelastic solids. The pre-selection also considered two denoising strategies to improve CNR: a low-pass filter with automatic frequency cutoff determination, and singular value decomposition of shear wave displacements. After pre-selection, the descriptor-denoising combination that produced the largest CNR was applied to SWEI cervix data from 18 pregnant Rhesus macaques acquired at weeks 10 (mid-pregnancy stage) and 23 (late pregnancy stage) of the 24.5-weeks full pregnancy. A maximum likelihood linear mixed-effects model (LME) was used to evaluate the dependence of the dispersion descriptor on pregnancy stage, maternal age, parity and other experimental factors. The pre-selection study showed that descriptor S combined with singular value decomposition produced a CNR 11.6 times larger than the other descriptor and denoising strategy combinations. In the Non-Human Primates (NHP) study, the LME model showed that descriptor S significantly decreased from mid to late pregnancy (−0.37 ± 0.07 m/s-kHz per week, p< 0.00001) with respect to the base value of 15.5 ± 1.9 m/s-kHz. This change was more significant than changes in other SWEI features such as the group velocity previously reported. Also, S varied significantly between the anterior and posterior portions of the cervix (p= 0.02) and with maternal age (p= 0.008). Given the potential of shear wave dispersion to track cervical remodeling, we will extend its application to ongoing longitudinal human studies.

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Section: Discussionmentioning

confidence: 99%

Shear Wave Dispersion as a Potential Biomarker for Cervical Remodeling During Pregnancy: Evidence From a Non-Human Primate Model

et al. 2021

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“…All data processing was done in custom software programmed in MATLAB R2021a (The MathWorks, Natick, MA). A parametric imaging strategy was followed to process the data, which consists of scanning an entire region of interest (ROI), that is, the entire image of the lesion, with a parameter estimation region (PER) 16,38,42,43 . From the RF signals contained within the PER, a single power spectrum was obtained from which a single backscatter coefficient was calculated.…”

Section: Methodsmentioning

confidence: 99%

“…From the fit, the value of the noise level at 6 MHz (approximate spectral center frequency) was estimated. The analysis bandwidth was defined by the interval of frequencies in which the value of the spectrum was 10 dB above the estimated value of the noise at 6 MHz 43 . In this way, the minimum frequency, maximum frequency, and central frequency (average between the minimum and maximum frequencies) were obtained for the power spectrum of the references and of all the acquisitions obtained from the 29 lesions.…”

Section: Methodsmentioning

confidence: 99%

“…A parametric imaging strategy was followed to process the data, which consists of scanning an entire region of interest (ROI), that is, the entire image of the lesion, with a parameter estimation region (PER). 16,38,42,43 From the RF signals contained within the PER, a single power spectrum was obtained from which a single backscatter coefficient was calculated. As the PER moves throughout the ROI, a 2-dimensional array of backscatter coefficients at the center frequency was obtained, which were then assigned colors to form the parametric image.…”

Section: Backscatter Coefficient Calculationmentioning

confidence: 99%

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Inter‐ and Intra‐Operator Variability of Regularized Backscatter Quantitative Ultrasound for the Characterization of Breast Masses

Argueta‐Lozano,

Castañeda‐Martinez,

Bass

et al. 2023

J of Ultrasound Medicine

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ObjectivesHere we report on the intra‐ and inter‐operator variability of the backscatter coefficient (BSC) estimated with a new low‐variance quantitative ultrasound (QUS) approach applied to breast lesions in vivo.MethodsRadiofrequency (RF) echo signals were acquired from 29 BIRADS 4 and 5 breast lesions in 2 sequential cohorts following 2 imaging protocols: cohort 1) radial and antiradial views, and cohort 2) short‐ and long‐axis views. Protocol 2 was implemented after retraining and discussion on how to improve reproducibility. Each patient was scanned by at least 2 of 3 radiologists; each performed 3 acquisitions with transducer and patient repositioning in between acquisitions. BSC was estimated using a low‐variance QUS approach based on regularization. Intra‐ and inter‐operator variability of the intra‐lesion median BSC was evaluated with a multifactorial ANOVA test (P‐values) and the intraclass correlation coefficient (ICC).ResultsInter‐operator variability was only significant in the first protocol (P < .007); ICCinter = .77 (95% CI .71–.82), indicating good inter‐operator agreement. In the second protocol, the inter‐operator variability was not significant (P > .05) and agreement was excellent (ICCinter = .92 [.89–.94]). In both protocols, the intra‐operator variability was not significant.ConclusionsOur findings demonstrate the need for standardizing image acquisition protocols for backscatter‐based QUS to reduce inter‐operator variability and ensure its successful translation to the characterization of suspicious breast masses.

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Optimization of Ultrasound Backscatter Spectroscopy to Assess Neurotoxic Effects of Anesthesia in the Newborn Non-human Primate Brain

Cited by 2 publications

References 75 publications

Shear Wave Dispersion as a Potential Biomarker for Cervical Remodeling During Pregnancy: Evidence From a Non-Human Primate Model

Shear Wave Dispersion as a Potential Biomarker for Cervical Remodeling During Pregnancy: Evidence From a Non-Human Primate Model

Inter‐ and Intra‐Operator Variability of Regularized Backscatter Quantitative Ultrasound for the Characterization of Breast Masses

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