SARUS: A synthetic aperture real-time ultrasound system

Jensen, Jørgen Arendt; Holten-Lund, Hans Erik; Nilsson, Ronnie Thorup; Hansen, Martin; Larsen, Ulrik; Domsten, R. P.; Tomov, Borislav Gueorguiev; Stuart, Matthias Bo; Nikolov, Svetoslav Ivanov; Pihl, Michael Johannes; Du, Yigang; Rasmussen, Joachim; Rasmussen, Morten Fischer

doi:10.1109/tuffc.2013.2770

Cited by 226 publications

(192 citation statements)

References 61 publications

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“…The measurements are performed with the experimental Synthetic Aperture Real-time Ultrasound System (SARUS) [6]. All measurements are performed in oil for electrical insulation of the uncoated part of the device.…”

Section: Measurements and Discussionmentioning

confidence: 99%

Investigation of PDMS as coating on CMUTs for imaging

Cour

Stuart

Laursen

et al. 2014

2014 IEEE International Ultrasonics Symposium

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Abstract-A protective layer is necessary for Capacitive Micromachined Ultrasonic Transducers (CMUTs) to be used for imaging purpose. The layer should both protect the device itself and the patient while maintaining the performance of the device. In this work Sylgard 170 PDMS is tested as coating material for CMUTs through comparison of transmit pressure and receive sensitivity in immersion of coated and uncoated elements. It is seen that the transmitted pressure decreases with 27% and the receive sensitivity decreases 35 % when applying the coating using a dam and fill principle. This matches well with the estimated value of 31 %. With the coating, the center frequency was found to be decreased from 4.5 MHz to 4.1 MHz and the fractional bandwidth was increased from 77 % to 84 % in transmit. In receive the center frequency was found to decrease from 4.4 MHz to 3.9 MHz and the fractional bandwidth was decreased from 108 % to 92 %, when applying the PDMS coating.

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Section: Measurements and Discussionmentioning

confidence: 99%

Investigation of PDMS as coating on CMUTs for imaging

Cour

Stuart

Laursen

et al. 2014

2014 IEEE International Ultrasonics Symposium

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“…The approach is implemented on the experimental scanner SARUS [11] for acquisition of channel RF data. A 192-element 4.1 MHz transducer is employed (pitch 0.6λ).…”

Section: A Measurement Setupmentioning

confidence: 99%

In vivo high frame rate vector flow imaging using plane waves and directional beamforming

Jensen

Hoyos

Stuart

et al. 2016

2016 IEEE International Ultrasonics Symposium (IUS)

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Abstract-Directional beamforming (DB) estimates blood flow velocities accurately when the flow angle is known. However, for automatically finding the flow angle a computationally expensive approach is used. This work presents a method for estimating the flow angle using a combination of inexpensive transverse oscillation (TO) estimators and only 3 directional beamformed lines. The suggested DB vector flow estimator is employed with steered plane wave transmissions for high frame rate imaging. Two distinct plane wave sequences are used: a short sequence (3 angles) for fast flow and an interleaved long sequence (21 angles) for both slow flow and B-mode. Parabolic flow with a peak velocity of 0.5 m/s is measured at beam-to-flow angles of 60• and 90• . The DB method estimates the angle with a bias and standard deviation (STD) less than 2• , and the STD of the velocity magnitude is 2.5 %. This is 7 -8.5 % when using TO. The long sequence has a higher sensitivity, and when used for estimation of slow flow with a peak velocity of 0.04 m/s, the SD is 2.5 % and bias is 0.1 %. This is a factor of 4 better than if the short sequence is used. The carotid bifurcation was scanned on a healthy volunteer, and the short sequence was used with TO and DB to estimate velocity vectors. The STD of the velocity profile over a cardiac cycle was 6.1 % for TO and 4.9 % for DB.

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“…The velocity estimation approach has been implemented on the SARUS experimental scanner [19]. A BK Medical 8820e convex array transducer was employed and vector flow imaging (VFI) in a single direction was interleaved with a B-mode image.…”

Section: Performancementioning

confidence: 99%

Improved vector velocity estimation using Directional Transverse Oscillation

Jensen

2015

2015 IEEE International Ultrasonics Symposium (IUS)

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Abstract-A method for estimating vector velocities using transverse oscillation (TO) combined with directional beamforming is presented. Directional Transverse Oscillation (DTO) is selfcalibrating, which increase the estimation accuracy and finds the lateral oscillation period automatically. A normal focused field is emitted and the received signals are beamformed in the lateral direction transverse to the ultrasound beam. A lateral oscillation is obtained by having a receive apodization waveform with two separate peaks. The IQ data are obtained by making a Hilbert transform of the directional signal, and a modified TO estimator can be used to find both the lateral and axial velocity. The approach is self-calibrating as the lateral oscillation period directly is estimated from the directional signal through a Fourier transform. The approach was implemented on the SARUS scanner using a BK Medical 8820e transducer with a focal point at 105.6 mm (F#=5) for Vector Flow Imaging (VFI). A 6 mm radius tube in a circulating flow rig was scanned and the parabolic volume flow of 112.7 l/h (peak velocity 0.55 m/s) measured by a Danfoss Magnetic flow meter for reference. Velocity estimates for DTO are found for 32 emissions at a 90 degrees beam-to-flow angle at a vessel depth of 30 mm. The standard deviation (SD) drops from 9.14% for TO to 5.4%, when using DTO. The bias is -5.05% and the angle is found within +/-3.93 degrees. At 70 mm a relative SD of 7% is obtained, the bias is -1.74%, and the angle is found within +/-2.6 degrees showing a low bias across depths.

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SARUS: A synthetic aperture real-time ultrasound system

Cited by 226 publications

References 61 publications

Investigation of PDMS as coating on CMUTs for imaging

Investigation of PDMS as coating on CMUTs for imaging

In vivo high frame rate vector flow imaging using plane waves and directional beamforming

Improved vector velocity estimation using Directional Transverse Oscillation

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