Development of Parametric Imaging of Myocardial Perfusion Using Ultrasonic Microbubble Destruction

我们设计了一种新的利用超声脉冲序列的间歇成像，该序列利用超声微泡破坏来定量心肌血流量(MBF)。我们设计了一种新的间歇成像序列，利用超声微泡破坏来定量心肌血流量(MBF)。我们发现在静脉注射微泡时，心肌声学造影的超声脉冲间隔(PI)突然缩短会导致对比强度(CI)沿帧数(F)的衰减，这符合衰减函数SI=α×EXP(-β×f)+γ。我们使用流动模型进行的体外研究表明，由此得到的α和β反映了流动传递速度。随后，我们进行了一项体内研究，使用从该公式得出的新参数成功地定量了大鼠的MBF。通过将心肌速度定义为Vel=1/(β/HR)，其中HR为心率，将心肌血容量定义为Vol=α+γ，将Mbf确定为VelxVol…更多=[1/(β/HR)](α+γ)。在基线、药物性充血和冠状动脉狭窄期间，测定的MBF与微球来源的MBF密切相关。最后，我们在临床环境中验证了该方法。用谐波能量多普勒和临床上可买到的微泡获得的参数，我们检查了脉冲序列的有用性。在静脉注射微泡时，PI从1：10缩短到1：1收缩末期心电触发器所产生的CI衰减程度也表现出类似的衰减。CI衰变程度：α/(α+γ)有助于量化冠状动脉血管扩张剂储备，其敏感性为93%，特异性为85%。此外，多帧触发器发射4个快速脉冲的突发被发现在标准化心肌中的微泡浓度方面是有用的。从微泡注药后开始出现节段性心肌显影到最后一次脉冲未出现心肌显影为止的时间长短与心肌血容量相关，从而通过心肌梗死节段患者对201-Tl的摄取来评价心肌存活性。较少

We devised a new intermittent imaging employing an ultrasound pulsing sequence that utilized ultrasonic microbubble destruction to quantitate myocardial blood flow (MBF).We devised a new intermittent imaging employing an ultrasound pulsing sequence that utilized ultrasonic microbubble destruction to quantitate myocardial blood flow (MBF). We found that abrupt shortening of ultrasound pulsing interval (PI) in myocardial contrast echocardiography during intravenous microbubble infusion produces a decay of contrast intensity (CI) along frame number (f), which fit tell to a decay function SI=α×exp(-β×f)+γ. Our study in vitro using a flow model revealed that α and β thus obtained reflect flow transit velocity. Subsequently, we performed an in vivo study in which MBF in rats was successfully quantitated with the new parameters derived from this formula. By defining myocardial velocityas Vel=1/(β/HR), where HR is heart rate, and myocardial blood volume as Vol=α+γ, MBF is determined as VelxVol … More = [1/(β/HR)](α+γ). MBF thus determined exhibited a close correlation with microsphere-derived MBF at baseline, during pharmacological hyperemia, and during coronary stenoses.Finally, we validated this method in clinical settings. The parameters obtained with harmonic power Doppler and commercially available microbubbles for clinical use, we examined the usefulness of the pulsing sequence. The extent of CI decay produced by PI shortening from 1:10 to 1:1 end-systolic ECG trigger during intravenous microbubble infusion exhibited a similar decay. The extent of CI decay:α/(α+γ) was found useful in quantification of coronary vasodilator reserve, which allowed defection of significant coronary stenoses with a sensitivity of 93 % and a specificity of 85%. In addition, multi-frame trigger that emitted a burst of 4 rapid pulses was found useful in standardizing microbubble concentration in the myocardium. The time duration from the beginning of segmental myocardial opacification after bolus microbubble injection to the burst in which the last pulse resulted in no opacification was correlated with myocardial blood volume, and thus the myocardial viability evaluated by 201-thallium uptake in infarcted segments inpatients. Less