aJulius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands bDepartment of Medicine, Uppsala University Hospital, Uppsala, Sweden cMedical UltraSound Imaging Centre, Radboud University Nijmegen Medical Centre, Nijmegen dDepartment of Experimental Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands.
J Hypertens. 2013 Sep;31(9):1861-7. doi: 10.1097/HJH.0b013e3283623548.
B-mode ultrasound measurements of the echolucency of the carotid intima-media may hold information on cardiovascular risk. The information obtained from this measurement may depend on which gain settings are used. We studied the effect of gain settings on echolucency measurements and its consequences on risk factor relations and treatment effects.
We used two approaches. In the first, we examined the relationship between calibration, gain and common grey-scale median (GSM) from repeated ultrasound images obtained from four healthy individuals at gain settings ranging from -20 to 20 dB. In the second, we evaluated the effect of gain settings on the relation of risk factors and statin treatment with common GSM, using images from 325 participants of the Measuring Effects on Intima-Media Thickness: an Evaluation of Rosuvastatin (METEOR) study with documented gain settings. Echolucency of the carotid intima-media was measured from ultrasound images using PaintShop Pro and Artery Measurement Software and expressed as GSM.
In healthy individuals, common GSM increased with increments in gain setting, primarily when the measurements were not calibrated. In the METEOR study sample, age and sex were significantly related to gain setting. The risk factor relations with common GSM were of the same magnitude and direction after adjustment for gain setting. Furthermore, adjustment for gain setting did not alter the rates of GSM change over time.
Extreme variability in gain settings has a major impact on the echolucency measurements of the far wall common carotid intima-media. Calibration should be used to adjust for these effects of gain settings. Variability in gain settings, however, seems limited in real practice and did not change the direction and magnitude of the relations under study. However, as age and sex are major determinants of gain settings, adjustment for or stratification by age and sex is recommended in studies into echolucency of the carotid intima-media in situations in which gain settings are unknown.
颈动脉内膜中层的超声回声衰减的 B 型模式测量可能提供心血管风险的信息。该测量值获得的信息可能取决于所使用的增益设置。我们研究了增益设置对回声衰减测量的影响及其对危险因素关系和治疗效果的影响。
我们使用了两种方法。首先，我们检查了来自四个健康个体的重复超声图像的校准、增益和通用灰度中位数（GSM）之间的关系，增益设置范围为-20 至 20dB。其次，我们使用 METEOR 研究中 325 名记录增益设置的参与者的图像，评估了增益设置对危险因素和他汀类药物治疗与通用 GSM 之间关系的影响。使用 PaintShop Pro 和动脉测量软件从超声图像中测量颈动脉内膜中层的回声衰减，并表示为 GSM。
在健康个体中，GSM 随着增益设置的增加而增加，尤其是在未校准的情况下。在 METEOR 研究样本中，年龄和性别与增益设置显著相关。在调整增益设置后，危险因素与通用 GSM 的关系具有相同的幅度和方向。此外，调整增益设置不会改变 GSM 随时间的变化率。
增益设置的极端变化对远壁常见颈动脉内膜中层的回声衰减测量有重大影响。应使用校准来调整增益设置的这些影响。然而，在实际实践中，增益设置的可变性似乎有限，并且不会改变所研究关系的方向和幅度。但是，由于年龄和性别是增益设置的主要决定因素，因此建议在增益设置未知的情况下，在研究颈动脉内膜中层回声衰减时，对年龄和性别进行调整或分层。
