Ultrasonic mapping of the microvasculature: signal alignment

Zagar, Bernhard G.; Fornaris, R.J.; Ferrara, Katherine W.

doi:10.1016/s0301-5629(98)00042-8

Cited by 27 publications

(13 citation statements)

References 18 publications

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“…Within one line-of-sight, the peak magnitude of the cross-correlation between each adjacent pulse pair is found, and the alignment can be achieved by shifting each of the pulses by the determined amount. 20 The technique for velocity estimation is the auto-correlation technique introduced by Kasai et al 21 A sequence of A-mode RF signals is obtained from transmissions in the same beam direction, and the flow velocity is calculated using the phase shift information. The Doppler ensemble length is determined by the scan speed and ultrasound PRF.…”

Section: Signal Processing Strategies Of Doppler Ultrasoundmentioning

confidence: 99%

“…1, the fresh sheep blood with different sO 2 levels flows through the corresponding vessels embedded in tissue-mimicking base at different flow rates, and imaged by the combined system. Mean flow speeds were quantified from color Doppler images and plotted against preset values (10,20,40,60, and 80 mm∕s) with linear least-square fitting in Fig. 7.…”

Section: In Vitro Phantom Study Of Oxygen Flux Estimationmentioning

confidence: 99%

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Blood oxygen flux estimation with a combined photoacoustic and high-frequency ultrasound microscopy system: a phantom study

et al. 2012

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Abstract. The metabolic rate of oxygen consumption, an important indicator of tissue metabolism, can be expressed as the change of net blood oxygen flux into and out of a tissue region per 100 g of tissue. In this work, we propose a photoacoustic and Doppler ultrasound method for imaging local blood oxygen flux of a single vessel. An imaging system for combined photoacoustic and high-frequency ultrasound microscopy is presented. This system uses a swept-scan 25-MHz ultrasound transducer with confocal dark-field laser illumination optics. A pulse-sequencer enables ultrasonic and laser pulses to be interlaced so that photoacoustic and Doppler ultrasound images are co-registered. Since the mean flow speed can be measured by color Doppler ultrasound, the vessel cross-sectional area can be measured by power Doppler or structural photoacoustic imaging, and multi-wavelength photoacoustic methods can be used to estimate oxygen saturation (sO 2 ) and total concentration of haemoglobin (C Hb ), all of the parameters necessary for oxygen flux estimation can be provided. The accuracy of the flow speed and sO 2 estimation has been investigated. In vitro sheep blood phantom experiments have been performed at different sO 2 levels and mean flow speeds. Blood oxygen flux has been estimated, and the uncertainty of the measurement has been quantified.

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Section: Signal Processing Strategies Of Doppler Ultrasoundmentioning

confidence: 99%

Section: In Vitro Phantom Study Of Oxygen Flux Estimationmentioning

confidence: 99%

Blood oxygen flux estimation with a combined photoacoustic and high-frequency ultrasound microscopy system: a phantom study

et al. 2012

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“…Three correlation-based alignment algorithms have been proposed for compensation purpose: single reference line, incremental, and averaging. 10 The first strategy selects a single pulse within a line of sight as reference and aligns other pulses by the relative shifts. The second calculates the relative shifts of consecutive pulses and aligns each pulse with the previous one.…”

Section: Signal Processing Strategiesmentioning

confidence: 99%

Photoacoustic and high-frequency power Doppler ultrasound biomicroscopy: a comparative study

et al. 2010

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Abstract. Both photoacoustic imaging and power Doppler ultrasound are capable of producing images of the vasculature of living subjects, however, the contrast mechanisms of the two modalities are very different. We present a quantitative and objective comparison of the two methods using phantom data, highlighting relative merits and shortcomings. An imaging system for combined photoacoustic and highfrequency power Doppler ultrasound microscopy is presented. This system uses a swept-scan 25-MHz ultrasound transducer with confocal dark-field laser illumination optics. A pulse-sequencer enables ultrasonic and laser pulses to be interlaced so that photoacoustic and power Doppler ultrasound images can be coregistered. Experiments are performed on flow phantoms with various combinations of vessel size, flow velocity, and optical wavelength. For the task of blood volume detection, power Doppler is seen to be advantageous for large vessels and high flow speeds. For small vessels with low flow speeds, photoacoustic imaging is seen to be more effective than power Doppler at the detection of blood as quantified by receiver operating characteristic analysis. A combination of the two modes could provide improved estimates of fractional blood volume in comparison with either mode used alone.

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“…This distortion was due to the transducer moved along the contour of the object during image acquisition, and so signals of the original shape from different vertical levels may be considered to have been obtained from the same positions. Therefore, an alignment process was implemented to reconstruct the original image, which was based on the strong correlation between adjacent pairs of ultrasonic signals separated by a 1-lm interval [24]. The alignment process was performed as follows: Let P i and P r represent two ultrasonic signals to be calculated by the cross-correlation whose cross-correlation is expressed aŝ R P i Pr ðmÞ ¼ where P i is any ultrasonic signal in the preliminary image, P r is a standard ultrasonic signal, and N is the length of the ultrasonic signal.…”

Section: Skin-scanning Technique In the High-frequency Ultrasound Imamentioning

confidence: 99%

Skin-scanning technique for superficial blood flow imaging using a high-frequency ultrasound system

2014

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Ultrasonic mapping of the microvasculature: signal alignment

Cited by 27 publications

References 18 publications

Blood oxygen flux estimation with a combined photoacoustic and high-frequency ultrasound microscopy system: a phantom study

Blood oxygen flux estimation with a combined photoacoustic and high-frequency ultrasound microscopy system: a phantom study

Photoacoustic and high-frequency power Doppler ultrasound biomicroscopy: a comparative study

Skin-scanning technique for superficial blood flow imaging using a high-frequency ultrasound system

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