Key result
Power Doppler imaging with a lower contrast dose (0.1 mL/min) provided better correlation with myocardial blood flow (r=0.77, P<0.0001) than gray-scale imaging at a higher dose (0.2 mL/min).
Why the study?
Does a lower dose of contrast agent improve the assessment of coronary stenosis using power Doppler imaging compared to gray-scale imaging in a canine model?
Does a lower dose of contrast agent improve the assessment of coronary stenosis using power Doppler imaging compared to gray-scale imaging in a canine model?
Power Doppler imaging requires a lower dose of contrast agent than gray-scale imaging to accurately detect milder coronary stenosis and avoid saturation.
May support lower-dose power Doppler for myocardial perfusion in preclinical models; leaves open human validation for coronary stenosis assessment.
RATIONALE AND OBJECTIVES: In myocardial contrast echocardiography (MCE), power Doppler imaging is more sensitive to contrast agent (microbubble) than gray-scale B-mode imaging; however, no data exist regarding the optimal contrast dose in power Doppler imaging. This study examined the optimal dose of contrast agent for power Doppler in assessing coronary stenosis. METHODS: Three grades of coronary stenosis were produced in 6 open-chest dogs. MCE was performed with gray-scale and power Doppler during continuous infusion of 0.2 mL/min FS-069. Thereafter, MCE was repeated with power Doppler during continuous infusion of 0.1 mL/min FS-069. RESULTS: Although the videointensity in the stenosed bed with power Doppler (214 +/- 14) was greater than gray scale (35 +/- 17) during 0.2 mL/min FS-069 infusion (P < 0.0001), power Doppler failed to identify milder coronary stenoses because videointensity in stenosed bed was quickly saturated with contrast agent. The videointensity in the stenosed bed with power Doppler (127 +/- 49) during 0.1 mL/min FS-069 infusion was greater than gray scale (35 +/- 17) during 0.2 mL/min FS-069 infusion (P < 0.0001), and all levels of stenosis were identified with power Doppler, even though the dose of contrast agent was half of that of gray scale imaging. The correlation between videointensity and myocardial blood flow was better in the case of power Doppler at 0.1 mL/min FS-069 infusion (r = 0.77, P < 0.0001) than in the case of gray scale imaging at 0.2 mL/min FS-069 infusion (r = 0.66, P < 0.01). CONCLUSIONS: These data support the need for a lower dose of contrast agent for power Doppler than for gray scale to detect milder coronary stenosis and avoid saturation of imaging fields.
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Masugata et al. (2003) studied Coronary stenosis (n=6). Power Doppler imaging with FS-069 contrast agent vs. Gray-scale imaging with 0.2 mL/min FS-069 was evaluated on Videointensity in the stenosed bed and correlation with myocardial blood flow (r = 0.77, p=< 0.0001). Power Doppler imaging with a lower contrast dose (0.1 mL/min) provided better correlation with myocardial blood flow (r=0.77, P<0.0001) than gray-scale imaging at a higher dose (0.2 mL/min).
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