Dr. Marko Jakovljevic Profile

Dr. Marko Jakovljevic

at Stanford Univ School of Medicine

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Author

Publications (5)

Proceedings Article | 15 March 2019 Presentation + Paper

Estimating signal and structured noise in ultrasound data using prediction-error filters

Joseph Jennings, Marko Jakovljevic, Ettore Biondi, Jeremy Dahl, Biondo Biondi

Proceedings Volume 10955, 109550R (2019) https://doi.org/10.1117/12.2513514

KEYWORDS: Electronic filtering, Tissues, Data modeling, Ultrasonography, Speckle, Wavefronts, Autoregressive models, Data acquisition, Multidimensional signal processing

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When using ultrasound to image heterogeneous media, echoes from multiple and off-axis scattering can overwrite the recorded ballistic wavefronts of interest. This reduces the coherence of signals across the aperture and causes clutter in the final image. Therefore, separating those unwanted events from the signal of interest is necessary to improve the visibility of structures in a B-mode image, and also to enable other processing methods that require coherent channel signals, such as various phase-aberration-correction techniques and sound-speed estimators. We used prediction-error filters (PEFs) to model the signal and the assumed additive noise in the data acquired through a 10 mm thick layer of beef tissue placed above a speckle region of a phantom. The PEF coefficients used to model the signal were first computed from the phantom data collected without tissue and subsequently employed to deconvolve the tissue data and find the PEF associated with the noise. These two filters were then used in a joint-inversion framework to separate the signal and noise components recorded within the original tissue data. In order to be able to apply our method in scenarios where direct measurements of the signal proxy are not available, we also evaluated the signal-PEF coefficients from the theoretical model of the signal from diffuse targets as provided by the van-Cittert Zernike (VCZ) theorem. To evaluate the quality of the separation of signal from the noise, we compared the original channel data acquired through the tissue with its estimated ballistic-wave component, as well as their corresponding spectra. We also compared performance of the proposed technique to F-X filter, which is a popular linear-predictionbased filter used to suppress noise in channel data. After the removal of acoustic noise from the channel data, coherence across the aperture increases. The average nearest-neighbor cross-correlation computed on the original data is 0.47, while the nearest-neighbor cross-correlation of the estimated ballistic-wave component is 0.81 or 0.97, depending whether the experimental or theoretical signal-PEFs are used in the estimation process.

Proceedings Article | 15 March 2019 Presentation + Paper

Tracking blood flow changes in the brains of neonates using angular-coherence-based power doppler

Marko Jakovljevic, Byung Jason Yoon , Lotfi Abou-Elkacem, Erika Rubesova, Jeremy Dahl

Proceedings Volume 10955, 109550G (2019) https://doi.org/10.1117/12.2513554

KEYWORDS: Doppler effect, Brain, Blood circulation, Signal processing, Signal to noise ratio, Neuroimaging

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Proceedings Article | 1 April 2016 Paper

Detection of and compensation for blocked elements using large coherent apertures: ex vivo studies

Marko Jakovljevic, Nick Bottenus, Lily Kuo, Shalki Kumar, Jeremy Dahl, Gregg Trahey

Proceedings Volume 9790, 97900W (2016) https://doi.org/10.1117/12.2217385

KEYWORDS: Signal detection, Ultrasonography, Chest, Point spread functions, Acoustics, Visualization, Image restoration, Tissues, Image quality, Binary data, Spatial frequencies, Aberration correction

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Proceedings Article | 17 March 2015 Paper

Implementation of swept synthetic aperture imaging

Nick Bottenus, Marko Jakovljevic, Emad Boctor, Gregg Trahey

Proceedings Volume 9419, 94190H (2015) https://doi.org/10.1117/12.2081434

KEYWORDS: Transducers, Tissues, Point spread functions, Imaging systems, Image transmission, Ultrasonography, Image resolution, Chemical elements, Spatial frequencies, Image quality

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Proceedings Article | 25 March 2011 Paper

Improved detectability of hypoechoic regions with short-lag spatial coherence imaging: experimental validation

Marko Jakovljevic, Jeremy Dahl, Gregg Trahey

Proceedings Volume 7968, 79681E (2011) https://doi.org/10.1117/12.878348

KEYWORDS: Signal to noise ratio, Spatial coherence, In vivo imaging, Ultrasonography, Liver, Acoustics, Coherence imaging, Transducers, Target detection, Interference (communication)

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