High-Frame Rate Vector Flow Imaging Technique: Initial Application in Evaluating the Hemodynamic Changes of Carotid
Yijie Qiu1, Yi Dong1, Feng Mao1
1Department of Ultrasound, Zhongshan Hospital, Fudan University, Shanghai, China.
Insights
High-frame rate vector flow imaging (V flow) effectively evaluates hemodynamic changes in carotid stenosis. This non-invasive technique shows potential for assessing stenosis severity by correlating wall shear stress with blood flow dynamics.
Area of Science:
- Vascular Ultrasound
- Hemodynamics
- Medical Imaging
Background:
- Carotid stenosis, often caused by atherosclerotic plaques, poses a significant risk for cerebrovascular events.
- Accurate assessment of hemodynamic changes is crucial for determining the severity of carotid stenosis.
- Current imaging methods may have limitations in fully characterizing complex flow patterns within stenotic lesions.
Purpose of the Study:
- To evaluate the utility of high-frame rate vector flow imaging (V flow) in assessing hemodynamic alterations in carotid stenosis.
- To correlate V flow-derived measurements, such as wall shear stress (WSS), with established measures of stenosis severity and blood flow velocity.
- To explore the potential of V flow as a non-invasive tool for grading carotid artery stenosis.
Main Methods:
- Prospective study including 51 patients with carotid atherosclerotic plaques and stenosis ≥30%.
- Carotid stenosis graded as moderate (30-69%) or severe (70-99%) using North American Symptomatic Carotid Endarterectomy Trial criteria.
- High-frame rate V flow imaging and color Doppler ultrasound (Mindray Resona 7s) used to measure mean WSS and peak systolic velocity (PSV); digital subtraction angiography (DSA) served as the gold standard.
Main Results:
- V flow measurements were successfully performed in 100% of moderate and 88.2% of severe stenosis cases.
- Dynamic V flow imaging visualized fast blood flow (up to 260.92 cm/s) and altered streamlines at the stenotic segment.
- Mean WSS at the narrowest region showed moderate positive correlations with stenosis degree (r=0.58) and PSV (r=0.54) (P<0.05); significantly higher WSS in severe vs. moderate stenosis (1.47 ± 0.97 Pa vs. 0.96 ± 0.44 Pa, P<0.05).
Conclusions:
- High-frame rate V flow imaging effectively visualizes hemodynamic changes in carotid stenosis.
- V flow-derived mean WSS correlates with stenosis severity and PSV, suggesting its utility in assessment.
- V flow represents a promising non-invasive imaging modality for evaluating the degree of carotid stenosis.
Abstract:
Objective: To investigate the value of high-frame rate vector flow imaging technique (V flow) in evaluating the hemodynamic changes of carotid stenosis caused by atherosclerotic plaques. Methods and Materials: In this prospective study, patients with stenosis rate (diameter) ≥30% caused by carotid atherosclerotic plaques were included. Degrees of carotid stenosis were graded according to North American Symptomatic Carotid Endarterectomy Trial criteria: moderate (30-69%) or severe (70-99%). Mindray Resona 7s ultrasound machine with a linear array transducer (3-11 MHz) was used for ultrasound examinations. The mean WSS value of carotid arteries was measured at the proximal, narrowest region and distal of carotid stenosis. The mean WSS values were correlated with peak systolic velocity (PSV) measured by color Doppler flow imaging and stenosis degree detected by digital subtraction angiography (DSA). The vector arrows and flow streamline detected by V flow dynamic imaging were analyzed. Imaging findings of DSA in carotid arteries were used as the gold standard. Results: Finally, 51 patients were included. V flow measurements were performed successfully in 17 patients (100%) with moderate-grade stenosis and in 30 patients (88.2%) with severe-grade stenosis. Dynamic V flow imaging showed yellow or red vectors at the stenotic segment, indicating fast speed blood flow (up to 260.92 cm/s). Changes of streamlines were detected in the stenotic segment. The mean WSS value measured at the narrowest region of the carotid artery had a moderately positive correlation with stenosis degree (r = 0.58, P < 0.05) and PSV value (r = 0.54, P < 0.05), respectively. Significant difference was detected in mean WSS value at the narrowest region of the carotid artery between severe carotid stenosis (1.47 ± 0.97 Pa) and moderate carotid stenosis (0.96 ± 0.44 Pa) (P < 0.05). Conclusion: The hemodynamic changes detected by V flow of the carotid stenosis might be a potential non-invasive imaging tool for assessing the degree of carotid stenosis.
