Arthritis Res Ther. 2013 Oct 24;15(5):R162. doi: 10.1186/ar4345.
In many patients with rheumatoid arthritis (RA) subclinical disease activity can be detected with ultrasound (US), especially using power Doppler US (PDUS). However, PDUS may be highly dependent on the type of machine. This could create problems both in clinical trials and in daily clinical practice. To clarify how the PDUS signal differs between machines we created a microvessel flow phantom.
The flow phantom contained three microvessels (150, 1000, 2000 microns). A syringe pump was used to generate flows. Five US machines were used. Settings were optimised to assess the lowest detectable flow for each US machine.
The minimal detectable flow velocities showed very large differences between the machines. Only two of the machines may be able to detect the very low flows in the capillaries of inflamed joints. There was no clear relation with price. One of the lower-end machines actually performed best in all three vessel sizes.
We created a flow phantom to test the sensitivity of US machines to very low flows in small vessels. The sensitivity of the power Doppler modalities of 5 different machines was very different. The differences found between the machines are probably caused by fundamental differences in processing of the PD signal or internal settings inaccessible to users. Machines considered for PDUS assessment of RA patients should be tested using a flow phantom similar to ours. Within studies, only a single machine type should be used.
在许多类风湿关节炎（RA）患者中，可以通过超声（US）检测到亚临床疾病活动，尤其是使用功率多普勒超声（PDUS）。然而，PDUS 可能高度依赖于机器的类型。这可能会在临床试验和日常临床实践中都带来问题。为了阐明 PDUS 信号在机器之间的差异，我们创建了一个微血管血流仿体。
该血流仿体包含三个微管（150、1000 和 2000 微米）。使用注射器泵产生流动。使用了五台 US 机器。对每个 US 机器进行了优化设置，以评估可检测到的最低流速。
最小可检测流速在机器之间存在很大差异。只有两台机器可能能够检测到发炎关节中毛细血管的极低流量。这与价格没有明显关系。实际上，一台低端机器在所有三个血管尺寸上的性能都最好。
我们创建了一个血流仿体来测试 US 机器对小血管中极低流速的敏感性。5 台不同机器的功率多普勒模式的敏感性差异很大。机器之间发现的差异可能是由于 PD 信号的处理或用户无法访问的内部设置的根本差异造成的。用于评估 RA 患者 PDUS 的机器应使用类似于我们的血流仿体进行测试。在研究中，应仅使用单一机器类型。
