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Abstract-This study presents the first quantification and visualization of secondary flow patterns with vector flow ultrasound. The first commercial implementation of the vector flow method Transverse Oscillation was used to obtain in-vivo, 2D vector fields in real-time. The hypothesis of this study was that the rotational direction is constant within each artery. Three data sets of 10 seconds were obtained from three main arteries in healthy volunteers. For each data set the rotational flow patterns were identified during diastole. Each data set contains a 2D vector field over time using the vector angles and velocity magnitudes the blood flow patterns were visualized using streamlines in Matlab (Mathworks, Natick, MA, USA). The rotational flow was quantified by the angular frequency for each cardiac cycle, and the mean rotational frequencies and standard deviations were calculated for the abdominal aorta {-1.3±0.4;-1.0±0.3;-0.9±0.2}Hz, the common iliac artery {-0.4±0.1;-1.0±0.2;-0.4±0.1}Hz, and the common carotid artery {0.8±0.3;1.4±0.3;0.4±0.1}Hz. A positive sign indicates an anti-clockwise rotation, and a negative sign indicates clockwise rotation. The sign of the rotational directions within each artery were constant.

Abstract-Blood velocity estimates using conventional color flow imaging (CFI) or Doppler techniques are angle dependent. One of the proposed techniques to overcome this limitation is the Transverse Oscillation (TO) method, which also estimates the lateral velocity components. The performance of this is evaluated on a commercial platform. Beamformed data are acquired using a commercial BK Medical scanner as opposed to the previously reported results obtained with the experimental scanner RASMUS. The implementation is evaluated using an in-house circulating flow rig by calculating the relative mean standard deviation and bias of the velocity components. The relative mean standard deviation decreases as the number of shots per estimate increases and a value of 5% is obtained for 64 shots per estimate. For a center frequency of 5 MHz at 60• , 75• , and 90• , the relative mean bias varies from 21% to 27% and is lowest at a transmit focal depth close to the center of the vessel. The present performance is comparable with the results from the experimental scanner and simulations. It is obtained with only few changes to the conventional CFI setup and further optimization can improve the performance. This illustrates the feasibility of implementing the TO method on a commercial platform for real-time estimation.

Abstract-A quantitative method for distinguishing complex from non-complex flow patterns in ultrasound is presented. A new commercial BK Medical ultrasound scanner uses the Transverse Oscillation vector flow technique for visualising flow patterns in real-time. In vivo vector flow data of the blood flow patterns of the common carotid artery and the carotid bulb were obtained simultaneously as the basis for quantifying complex flow. The carotid bifurcation of two healthy volunteers were scanned. The presence of complex flow patterns from eight cardiac cycles were evaluated by three experts in medical ultrasound. From the same data the mean standard deviation of the flow angles (MSTDA) were calculated and compared to the expert evaluations. Comparison between the combined experts evaluations and the MSTDA was performed. Using linear regression analysis, a correlation coefficient of 0.925 was found. The upper and lower bounds for a 95% confidence interval of 0.974 and 0.792 respectively, were calculated. The MSTDA was below 25• for the common carotid artery and above 25• for the carotid bulb. Thus, the MSTDA value can distinguishing complex flow from non-complex flow and can be used as the basis for automatic detection of complex flow patterns.

Abstract-The Transverse Oscillation method has shown its commercial feasibility, providing the user with 2D velocity information. Todays implementation on commercial ultrasound platforms only support linear array transducers and are limited in depth. Extending the implementation to a phased array transducer, vector velocity echocardiography will become possible. This paper describes the general modification made on the BK Medical 2202 Pro Focus UltraView using a 64 element phased array transducer and the simulations and measurements performed. The results show that velocities can be obtained at depths even greater than 100 mm. Tests at depths of 72 mm and 82 mm with a peak velocity of 0.5 m/s, showed a relative mean biasBv x that varied from 0 % and to 21 % and a relative mean standard deviationσv x that varied from 18 % and to 51 %. The investigation showed an increasing bias with respect to depth, which leaves room for optimization. Despite the bias, the method has shown to work and produce reliable results, and 2D velocity estimates are provided within the entire color-box down to a depth of more than 100 mm making vector velocity imaging possible in the entire heart.

. (2011). Preliminary comparison between real-time in-vivo spectral and transverse oscillation velocity estimates. In J.