Sathiyamoorthy Selladurai

Bio: Sathiyamoorthy Selladurai is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Elastography & Imaging phantom. The author has an hindex of 2, co-authored 7 publications receiving 21 citations.

Strategies to Obtain Subpitch Precision in Lateral Motion Estimation in Ultrasound Elastography

Abstract: In elastography, conventional linear array (CLA)-based RF data acquisition provides more accurate displacement measurements in the direction of beam propagation (axial direction) when compared to the perpendicular direction (lateral). Obtaining good quality lateral displacement estimates in ultrasound (US) elastography will lead to several benefits such as obtaining accurate inverse solutions, improving shear strain elastogram quality, getting good quality poroelastograms, and obtaining reliable rotation elastograms. For accomplishing high-precision lateral displacement estimation (LDE), one of the popular methods is by interpolating additional A-lines in between neighboring RF A-lines. We describe a method wherein true RF A-lines (not interpolated) are acquired and augmented at subpitch locations using CLA transducer, instead of interpolating the data, and using this new frame data for further image formation and/or processing to yield better lateral resolution and LDE. We demonstrate the proposed method by translating the US beam of CLA transducer in subpitch range by the following two approaches: 1) actuator-assisted beam translation and 2) electronic translation of subaperture of a CLA by activating odd and even number of consecutive elements sequentially, referred to as electronic beam translation. The performances of the different methods were studied through simulations and experiments on phantoms. The results demonstrate that these methods yield better quality LDE compared to those obtained from interpolation of RF A-lines. These methods may provide affordable ways to obtain subpitch precision LDE using CLA.

3D Cell Culture: Recent Development in Materials with Tunable Stiffness

Abstract: It is widely accepted that three-dimensional cell culture systems simulate physiological conditions better than traditional 2D systems. Although extracellular matrix components strongly modulate ce...

Incorporating Multiple Observations in global Ultrasound Elastography

Abstract: In this paper, we propose a novel framework for time delay estimation in ultrasound elastography. In the presence of high acquisition noise, the state-of-the-art motion tracking techniques suffer from inaccurate estimation of displacement field. To resolve this issue, instead of one, we collect several ultrasound Radio-Frequency (RF) frames from both pre- and post-deformed scan planes to better investigate the data statistics. We formulate a non-linear cost function incorporating all observation frames from both levels of deformations. Beside data similarity, we impose axial and lateral continuity to exploit the prior information of spatial coherence. Most importantly, we consider the continuity among the displacement estimates obtained from different observation RF frames. This novel continuity constraint mainly contributes to the robustness of the proposed technique to high noise power. We efficiently optimize the aforementioned cost function to derive a sparse system of linear equations where we solve for millions of variables to estimate the displacement of all samples of all of the incorporated RF frames simultaneously. We call the proposed algorithm GLobal Ultrasound Elastography using multiple observations (mGLUE). Our primary validation of mGLUE against soft and hard inclusion simulation phantoms proves that mGLUE is capable of obtaining high quality strain map while dealing with noisy ultrasound data. In case of the soft inclusion phantom, Signal-to-Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR) have improved by 75.37% and 57.08%, respectively. In addition, SNR and CNR improvements of 32.19% and 38.57% have been observed for the hard inclusion case.

Enhancing Image Quality of Photoacoustic Tomography Using Sub-Pitch Array Translation Approach: Simulation and Experimental Validation

Abstract: Objective : The purpose of this paper is to present a more convenient and practical alternate way of increasing the lateral discrete array sampling while using a typical λ pitch linear array transducer at receive for photoacoustic tomography (PAT) application. Methods: We have employed a linear translation-based approach, in which the array transducer is translated by sub-pitch amount to create an augmented RF frame data having denser lateral spatial sampling. The denser λ /2 and λ /4 pitch data were reconstructed and compared against conventional λ pitch reconstructed PAT image using simulation and tissue mimicking phantom experiments in terms of improvements in resolution and contrast. Results: The results from experiments demonstrate a 34.48% improvement in lateral resolution (LR), measured in terms of full-width at half-maximum of the lateral profile of point spread function, and a maximum of 7-dB improvement in contrast is achieved while using a λ /2-pitch configuration when compared to the conventional λ -pitch configuration. Conclusion: It was demonstrated that λ /2- and λ /4-pitch configurations result in better LR and contrast than λ -pitch configuration. Significance: Based on the results obtained, the proposed method has the potential to serve as an easy-to-integrate and simple way of achieving better image quality without requiring to increase the system complexity with existing transducer array probe technology in regular clinical scanners.