Preliminary study on estimation of flow velocity vectors using focused transmit beams

2021 ◽  
Author(s):  
Hideyuki Hasegawa ◽  
Michiya Mozumi ◽  
Masaaki Omura ◽  
Ryo Nagaoka ◽  
Kozue Saito
Keyword(s):  
Blood Flow ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Soft Tissues ◽  
Estimation Error ◽  
Frame Rate ◽  
High Frame Rate ◽  
In Vivo Measurement ◽  
Preliminary Study

Abstract High-frame-rate ultrasound imaging with plane wave transmissions is a predominant method for blood flow imaging, and methods for estimation of blood flow velocity vectors have been developed based on high-frame-rate imaging. On the other hand, in imaging of soft tissues, such as arterial walls and atherosclerotic plaques, high-frame-rate imaging sometimes suffers from high-level clutters. Even in observation of the arterial wall with a focused transmit beam, it would be highly beneficial if blood flow velocity vectors could be estimated simultaneously. We conducted a preliminary study on estimation of blood flow velocity vectors based on a multi-angle Doppler method with focused transmit beam and parallel receive beamforming. It was shown that the lowest estimation error was achieved at a steering angle of 25 degrees by simulation. Also, velocity vectors with typical velocity magnitudes and directions could be obtained by the proposed method in in vivo measurement of a carotid artery.

Preclinical Quantification of Prostate Cancer-Associated Vascular Alterations in the Bone Microenvironment in vivo

2020 ◽  
Vol 61 (6) ◽  
pp. 188-200
Author(s):  
Malte Schroeder ◽  
Lennart Viezens ◽  
Jördis Sündermann ◽  
Svenja Hettenhausen ◽  
Gerrit Hauenherm ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Blood Flow ◽  
Flow Velocity ◽  
Cell Lines ◽  
Blood Flow Velocity ◽  
Tumour Growth ◽  
Prostate Cancer Cell ◽  
Bone Microenvironment ◽  
Prostate Cancer Cell Lines

Introduction: Prostate cancer has a special predilection to form bone metastases. Despite the known impact of the microvascular network on tumour growth and its dependence on the organ-specific microenvironment, the characteristics of the tumour vasculature in bone remain unknown. Methods: The cell lines LNCaP, DU145, and PC3 were implanted into the femurs of NSG mice to examine the microvascular properties of prostate cancer in bone. Tumour growth and the functional and morphological alterations of the microvasculature were analysed for 21 days in vivo using a transparent bone chamber and fluorescence microscopy. Results: Vascular density was significantly lower in tumour-bearing bone than in non-tumour-bearing bone, with a marked loss of small vessels. Accelerated blood flow velocity led to increased volumetric blood flow per vessel, but overall perfusion was not affected. All of the prostate cancer cell lines had similar vascular patterns, with more pronounced alterations in rapidly growing tumours. Despite minor differences between the prostate cancer cell lines associated with individual growth behaviours, the same overall pattern was observed and showed strong similarity to that of tumours growing in soft tissue. Discussion: The increase in blood flow velocity could be a specific characteristic of prostate cancer or the bone microenvironment.

scholarly journals Noninvasive imaging of in vivo blood flow velocity using optical Doppler tomography

1997 ◽  
Vol 22 (14) ◽  
pp. 1119 ◽  
Author(s):  
Zhongping Chen ◽  
Thomas E. Milner ◽  
Shyam Srinivas ◽  
Xiaojun Wang ◽  
Arash Malekafzali ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Noninvasive Imaging ◽  
Doppler Tomography ◽  
Optical Doppler Tomography

Methods to measure blood flow velocity of red blood cells in vivo at the microscopic level

1986 ◽  
Vol 14 (2) ◽  
pp. 175-186 ◽  
Author(s):  
Dick W. Slaaf ◽  
Theo J. M. Jeurens ◽  
Geert Jan Tangelder ◽  
Robert S. Reneman ◽  
Theo Arts
Keyword(s):  
Blood Flow ◽  
Red Blood Cells ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Blood Cells ◽  
Microscopic Level ◽  
Measure Blood Flow

Transcranial Doppler Pulsatility Index: Not an Accurate Method to Assess Intracranial Pressure

Neurosurgery ◽  
2010 ◽  
Vol 66 (6) ◽  
pp. 1050-1057 ◽  
Author(s):  
Anders Behrens ◽  
Niklas Lenfeldt ◽  
Khalid Ambarki ◽  
Jan Malm ◽  
Anders Eklund ◽  
...  
Keyword(s):  
Blood Flow ◽  
Intracranial Pressure ◽  
Flow Velocity ◽  
Transcranial Doppler ◽  
Blood Flow Velocity ◽  
Pulsatility Index ◽  
Transcranial Doppler Sonography ◽  
Accurate Method ◽  
Mathematical Simulations

Abstract BACKGROUND Transcranial Doppler sonography (TCD) assessment of intracranial blood flow velocity has been suggested to accurately determine intracranial pressure (ICP). OBJECTIVE We attempted to validate this method in patients with communicating cerebrospinal fluid systems using predetermined pressure levels. METHODS Ten patients underwent a lumbar infusion test, applying 4 to 5 preset ICP levels. On each level, the pulsatility index (PI) in the middle cerebral artery was determined by measuring the blood flow velocity using TCD. ICP was simultaneously measured with an intraparenchymal sensor. ICP and PI were compared using correlation analysis. For further understanding of the ICP-PI relationship, a mathematical model of the intracranial dynamics was simulated using a computer. RESULTS The ICP-PI regression equation was based on data from 8 patients. For 2 patients, no audible Doppler signal was obtained. The equation was ICP = 23*PI + 14 (R2 = 0.22, P < .01, N = 35). The 95% confidence interval for a mean ICP of 20 mm Hg was −3.8 to 43.8 mm Hg. Individually, the regression coefficients varied from 42 to 90 and the offsets from −32 to +3. The mathematical simulations suggest that variations in vessel compliance, autoregulation, and arterial pressure have a serious effect on the ICP-PI relationship. CONCLUSIONS The in vivo results show that PI is not a reliable predictor of ICP. Mathematical simulations indicate that this is caused by variations in physiological parameters.

The Effects of Blood Flow on Blood Vessel Buckling Embedded in Surrounding Soft Tissues

2016 ◽  
Vol 08 (05) ◽  
pp. 1650065 ◽  
Author(s):  
M. Hosseini ◽  
M. A. Paparisabet
Keyword(s):  
Blood Flow ◽  
Blood Vessel ◽  
Blood Cell ◽  
Flow Velocity ◽  
Blood Vessels ◽  
Red Blood Cell ◽  
Blood Flow Velocity ◽  
Soft Tissues ◽  
Flexible Beam ◽  
Critical Buckling Pressure

When blood flows in vessel curved portion, the presence of curvature generates a centrifugal force that acts in the same manner as a compressive load. Therefore, blood flow velocity has an important effect on the stability of vessels. In this study, the blood vessel is simulated as a flexible beam conveying fluid base on Euler–Bernoulli beam theory, and various boundary conditions are represented for the modeled vessels. Then, analytical and numerical methods are deployed to extract desired parameters. The effects of blood flow, hematocrit and stiffness of surrounding tissues on the buckling critical pressure are investigated. The results show that the mentioned parameters have considerable effects on blood vessels stability. Several numerical findings illustrate a reduction in critical buckling pressure with increasing hematocrit and blood flow velocity. In addition, the size of red blood cell has a significant effect on critical buckling pressure in low hematocrits. As increasing red blood cell diameter decreases critical buckling pressure. Furthermore, because of blood viscosity, the non-uniformity effects of the blood flow on blood vessels stability are investigated by considering a modification factor. These results improve our understanding of blood vessels instability.

In vivo visualization method by absolute blood flow velocity based on speckle and fringe pattern using two-beam multipoint laser Doppler velocimetry

2016 ◽  
Vol 120 (8) ◽  
pp. 084701 ◽  
Author(s):  
Tomoaki Kyoden ◽  
Shoji Naruki ◽  
Shunsuke Akiguchi ◽  
Hiroki Ishida ◽  
Tsugunobu Andoh ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Laser Doppler Velocimetry ◽  
Fringe Pattern ◽  
Laser Doppler ◽  
Doppler Velocimetry ◽  
Visualization Method
Sign in / Sign up

Export Citation Format

Share Document