Temporal averaging of two-dimensional correlation functions for velocity vector imaging of cardiac blood flow

Takahashi, Hiroki; Hasegawa, Hideyuki; Kanai, Hiroshi

doi:10.1007/s10396-015-0620-x

Cited by 24 publications

(23 citation statements)

References 23 publications

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“…On the other hand, methods of processing element signals are feasible in highframe-rate imaging because much fewer transmissions are necessary to construct an ultrasonic image. High-frame-rate ultrasound realizes a very high temporal resolution of more than 1,000 frames per second, and it is an emerging technique for measuring shear wave propagation 26,27) and cardiovascular dynamics, [28][29][30][31][32][33][34] and for monitoring high intensity focused ultrasound (HIFU) treatment. 35,36) Thus, the image quality in high-frame-rate ultrasound should be improved.…”

Section: Introductionmentioning

confidence: 99%

Improvement of range spatial resolution of medical ultrasound imaging by element-domain signal processing

Hasegawa

2017

Jpn. J. Appl. Phys.

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The range spatial resolution is an important factor determining the image quality in ultrasonic imaging. The range spatial resolution in ultrasonic imaging depends on the ultrasonic pulse length, which is determined by the mechanical response of the piezoelectric element in an ultrasonic probe. To improve the range spatial resolution without replacing the transducer element, in the present study, methods based on maximum likelihood (ML) estimation and multiple signal classification (MUSIC) were proposed. The proposed methods were applied to echo signals received by individual transducer elements in an ultrasonic probe. The basic experimental results showed that the axial half maximum of the echo from a string phantom was improved from 0.21 mm (conventional method) to 0.086 mm (ML) and 0.094 mm (MUSIC).

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Section: Introductionmentioning

confidence: 99%

Improvement of range spatial resolution of medical ultrasound imaging by element-domain signal processing

Hasegawa

2017

Jpn. J. Appl. Phys.

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“…The advantages of BSI over VFM are its high temporal resolution and that fewer mathematical assumptions are required, as BSI is less angle dependent compared with colour Doppler 26. The use of BSI has thus far only been reported in small case presentations and has not been validated against other imaging techniques 7,8.…”

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confidence: 99%

Left ventricular vortex formation in preterm infants assessed by blood speckle imaging

2019

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Background A vortex is a rotational fluid structure formed by shearing of fluid layers. It forms during diastole in the left ventricle (LV) and helps redirect flow to the LV outflow tract for ejection, optimizing energy conservation. The aim of this study was to demonstrate the feasibility of detecting and analyzing LV vortices using a new ultrasound technique known as blood speckle imaging (BSI). Methods Conventional and BSI parameters were acquired in preterm infants referred for echocardiography. BSI feasibility and reliability were explored using highest frequency settings and optimized Nyquist limits. Vortex area was determined by tracing the outer vortex ring at maximum area. Peak vortex formation time (PVFT) was determined at time of maximum vortex area relative to the R‐wave, and vortex duration from frame‐by‐frame analysis of first appearance to vortex degradation. Results Left ventricle vortices were detected in 49 of the 50 preterm infants (weight 500–2020 g) with excellent intra‐ and inter‐observer reliability. Mean vortex area indexed to LV area was 0.19 (0.08). Peak vortex formation time was at 87 (7)% of the cardiac cycle, and vortex duration lasted 13 (4)% of the cardiac cycle. Vortex area correlated positively with LV length, end‐diastolic dimension, end‐diastolic volume, mitral annular (R +0.42, +0.50, +0.47, +0.50, all P < 0.01), and transmitral Vti (R +0.37, P < 0.01). PVFT correlated negatively with E, EA, and Ee’ (R −0.42, −0.47, −0.47, all P < 0.01). Conclusion Left ventricle vortex formation can be analyzed with two‐dimensional BSI and has the potential to complement existing parameters of cardiac health.

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“…The block matching method can estimate the motion velocity based on a function evaluating the similarity between signals in two successive frames. [31][32][33] )th frame, and the NCC between the template and target images is evaluated as )th frames and A n is the signal amplitude inside the 2D kernel and expressed as…”

Section: Block Matching Methodsmentioning

confidence: 99%

“…The averaging process in the slow-time (frame) direction was applied to decrease the variation of the peak position of the NCC function. 33) The frames for 0.03 s were used for temporal averaging of the NCC function in the simulation. To estimate a sub-sample displacement, the estimated NCC function was up-sampled using the reconstructive interpolation method.…”

Section: Block Matching Methodsmentioning

confidence: 99%

Preliminary study on modeling blood flow velocity profile for ultrasonic measurement of wall shear stress

Mozumi

Omura

Nagaoka

et al. 2023

Jpn. J. Appl. Phys.

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The wall shear stress (WSS) contains useful information for the diagnosis of vascular diseases. To improve the accuracy of WSS measurements by ultrasound, some studies have attempted to correct the underestimation of the WSS by approximating a blood flow velocity profile measured by ultrasound to a velocity distribution model such as a laminar flow. In this study, a blood flow velocity profile measured by ultrasound was modeled by the Womersley flow model, in order to correct underestimation of WSS in cases of measurements of vessels with complex geometries such as stenotic vessels. The simulation results showed that root mean square error of the estimated WSSs was 45.8% from the stenotic vessel with a stenotic ratio of 40% when the spatial gradient was estimated by fitting a linear model to the measured flow profile. Such error was improved from 45.8% to 25.3% by fitting a Womersley flow model to the measured blood velocity profile.

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Temporal averaging of two-dimensional correlation functions for velocity vector imaging of cardiac blood flow

Abstract: Our proposed method has the feasibility to visualize the vortex flow by velocity vector mapping without a contrast agent.

Cited by 24 publications

References 23 publications

Improvement of range spatial resolution of medical ultrasound imaging by element-domain signal processing

Improvement of range spatial resolution of medical ultrasound imaging by element-domain signal processing

Left ventricular vortex formation in preterm infants assessed by blood speckle imaging

Preliminary study on modeling blood flow velocity profile for ultrasonic measurement of wall shear stress

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