Ranke C, Trappe H J
Department of Cardiology and Angiology, University Hospital Herne, Ruhr-University Bochum.
Vasa. 1997 Aug;26(3):210-4.
Because of the wide range of recommended threshold values for carotid stenosis graduation we performed a prospective study to determine interobserver and interequipment variability of quantitative blood flow velocity measurements.
We recorded absolute blood flow velocities and velocity ratios in 21 patients with carotid artery stenosis using two colour coded duplex ultrasound systems an ATL Ultramark 9 HDI, and a Hewlett Packard SONOS 2500 system. The ATL system was used for the interobserver variation study, where each patient was examined twice on the same day. The Doppler angle was recorded together with blood flow velocities (peak systolic velocity and mean maximum velocity from the velocity-time-integral both in the stenosis jet and 4-5 cm distally in the cranial portion of the internal carotid artery off poststenotic turbulences).
The ATL system generated significantly higher blood flow velocity values as compared with the HP system (218 +/- 156 cm/s vs. 169 +/- 114 cm/s; p < 0.001). The Mean Velocity Ratio (the ratio of intrastenotic Vmean and poststenotic Vmean) was constant with both duplex systems. The HP system yielded 10% (Cl, 7-13%) lower predicted stenosis estimates than the ATL system with Vmax as the stenosis criterion. The stenosis estimates calculated from Mean Velocity Ratio values did not differ significantly. The 95% Cl for predicted diameter reduction between two observer was 13.6% (Vmax) and 15.4% (Mean Velocity Ratio).
Because of significant interequipment differences of colour coded duplex ultrasound systems we recommend calculation of the Mean Velocity Ratio to avoid interpatient and interequipment variation of absolute flow velocities. According to our interobserver variability study, a change of more than 15% diameter reduction on follow-up examinations indicates disease progression or regression.
由于颈动脉狭窄分级的推荐阈值范围较广，我们进行了一项前瞻性研究，以确定定量血流速度测量的观察者间和设备间变异性。
我们使用两台彩色编码双功超声系统（一台ATL Ultramark 9 HDI和一台惠普SONOS 2500系统）记录了21例颈动脉狭窄患者的绝对血流速度和速度比值。ATL系统用于观察者间变异研究，即每位患者在同一天接受两次检查。记录多普勒角度以及血流速度（狭窄射流处的收缩期峰值速度和速度时间积分的平均最大速度，以及颈内动脉颅部狭窄后4 - 5厘米处远离狭窄后湍流处的速度）。
与惠普系统相比，ATL系统产生的血流速度值显著更高（218±156厘米/秒对169±114厘米/秒；p<0.001）。平均速度比值（狭窄内平均速度与狭窄后平均速度之比）在两个双功系统中是恒定的。以Vmax作为狭窄标准时，惠普系统得出的预测狭窄估计值比ATL系统低10%（可信区间，7 - 13%）。根据平均速度比值计算出的狭窄估计值没有显著差异。两位观察者预测直径减小的95%可信区间为13.6%（Vmax）和15.4%（平均速度比值）。
由于彩色编码双功超声系统存在显著的设备间差异，我们建议计算平均速度比值，以避免患者间和设备间绝对流速的变异性。根据我们的观察者间变异性研究，随访检查中直径减小超过15%表明疾病进展或消退。
