Contrast analysis in ultrafast ultrasound blood flow imaging of jugular vein

Abstract

Purpose The contrasts of flowing blood in in vitro experiments using porcine blood and in vivo measurements of human jugular veins were analyzed to demonstrate that the hemorheological property was dependent on the shear rate. Methods Blood samples (45% hematocrit) suspended in saline or plasma were compared with examine the difference in viscoelasticity. Ultrafast plane-wave imaging at an ultrasonic center frequency of 7.5 MHz was performed on different steady flows in a graphite-agar phantom. Also, in vivo measurement was performed in young, healthy subjects and patients with diabetes. A spatiotemporal matrix of beamformed radio-frequency data was used for the singular value decomposition (SVD) clutter filter. The clutter-filtered B-mode image was calculated as the amplitude envelope normalized at the first frame in the diastolic phase to evaluate contrast. The shear rate was estimated as the velocity gradient perpendicular to the lateral axis. Results Although nonaggregated erythrocytes at a high shear rate exhibited a low echogenicity, the echogenicity in the plasma sample overall increased due to erythrocyte aggregation at a low shear rate. In addition, the frequency of detection of specular components, defined as components beyond twice the standard deviation of a contrast map obtained from a clutter-filtered B-mode image, increased in the porcine blood at a high shear rate and the venous blood in healthy subjects versus patients with diabetes. Conclusion The possibility of characterizing hemorheological properties dependent on the shear rate and diabetes condition was indicated using ultrafast plane-wave imaging with an SVD-based clutter filter.

Robust adversarial learning model to segment non-speckle regions in blood flow echo

“…The result of the conventional contrast method 16) was compared to that with deep learning model. The flow of the conventional contrast method is shown in Fig.…”

“…Our previous study has reported that a higher flow rate (high flow velocity) induces a higher rate of presence of nonspeckle regions in in vitro experiment using porcine blood. 16) Since the main component in blood is RBC, the detection of non-speckle regions may lead to the evaluation of blood properties such as viscoelasticity dependence, morphology, and acoustic impedance contrast between RBCs and plasma or other cells such as white blood cells and platelets. Also, in our previous study, the contrasts between vessel lumen and surrounding tissues have been analyzed.…”

“…The area ratio of non-speckle regions, defined as components beyond twice of the standard deviation of a contrast map, were detected from a clutter-filtered B-mode image. In this method, the area ratio of non-speckle regions increased in the porcine blood in the high flow velocity, and were more frequently detected in the venous blood of healthy subjects than diabetic subjects 16) in the range from several 5%-10%. However, this contrast analysis method is dependent on the analysis conditions such as degree of smoothing and threshold for outliers.…”

“…The performance of the developed learning model was evaluated in both in silico and experimental data of blood-mimicking fluid to compare among several conditions of the U-Net model without or with the adversarial learning 27) and conventional contrast thresholding method. 16) 2. Datasets…”

Investigation on vector Doppler method for carotid artery wall with focused transmit beams produced from a cross-shaped probe

“…Techniques for measuring cardiovascular function using ultrasound have been extensively studied [1][2][3] and assessment of the mechanical properties of compositions in a carotid arterial wall is useful for the diagnosis of atherosclerosis. The stiffness of a carotid arterial wall is evaluated by pulse wave velocity [4][5][6] and stiffness parameter β 7,8) with ultrasound in clinical situations.…”