How can the variability in ultrasound measurement of intima‐media thickness be reduced? Studies of interobserver variability in carotid and femoral arteries

Abstract

A critical component in scientific studies of most biological variables is the variation or error in measurements which leads to non-identical results of repeated measurements from the same subject. The aim of this study was to investigate whether the interobserver error (s) in measurement of intima-media thickness (IMT) in carotid and femoral arteries could be decreased if the mean value obtained using two ultrasound images from each of the right and left arteries was used in the analyses instead of the mean value obtained using images from only the right artery. In addition, we wished to evaluate two different reading procedures, one based on manual tracing of echo interfaces and the other on automated edge detection. In a methodological study, 50 subjects were examined with ultrasound twice in the same day by two independent laboratory technologists. The ultrasound images were analysed in two ways: using a computerized manual tracing analysing system and an automated analysing system. When both right and left carotid arteries were examined (manual reading), the interobserver error was smaller than that determined for the examination of only the right artery, for IMTmean in both the common carotid artery (P = 0.06) and the carotid artery bulb (P < 0.05). The interobserver error was also significantly smaller for double-sided vs. one-sided examination with automated reading of IMTmean in the common carotid artery (P < 0.01) and in the carotid artery bulb (P < 0.01). The coefficient of variation (CV) for measurement in the common carotid artery decreased from 8.6% (one-sided, manual reading) to 5.3% (double-sided, automated reading). The interobserver error in measurement of IMT in the common femoral artery did not improve by examination of both right and left arteries. The results from this study show that the interobserver errors in measurement of IMT can be decreased by using ultrasound images from both the right and the left carotid arteries, and that the use of an automated analysing system greatly simplifies the reading of ultrasound images with sustained low variability.

A comparison of ultrasound intima media thickness measurements of the left and right common carotid artery

“…4) No statistical significant differences were found between the automated and the manual IMT measurements for both CCA sides and therefore automated measurements may be used to replace the manual measurements. No significant differences between the automated and the manual IMT measurements were also reported in [6], [10]- [12], and [15]. The mean difference between the manual and the automated mean IMT measurements found in this study was 0.01 mm, which is in the same order as also found in other studies VOLUME 3, 2015 performed by our group [17], [18], [36], [37] and also documented in [4].…”

“…It was also shown in [14], that the CCA IMT may be possibly used in the prediction of possible infarct side, and in the prediction of potential risk of stroke by evaluating the IMT on both sides of the CCA. There have been few studies regarding the effect of carotid IMT sidedness on the various risk factors associated with carotid IMT [9]- [11], [15]. Because of the different anatomical origins of the left versus the right CCA, it was speculated that hemodynamics, age, gender, blood lipid level, blood glucose level, and other risk factors would have different effects depending on whether the left or right CCA was considered [9].…”

Preclinical Atherosclerosis and Inflammation in 61-Year-Old Men With Newly Diagnosed Diabetes and Established Diabetes

“…The laboratory technician performing the ultrasound examination was blinded to the clinical status of each subject. Interobserver variability for measurement of IMT in the common carotid artery (CCA) and the carotid artery bulb has been shown to be 5.3 and 6.0%, respectively (11). Both the left and right carotid arteries were scanned at the level of the bifurcation, and images for IMT measurements were recorded from the far wall in the CCA and in the carotid artery bulb.…”

Antibodies to Oxidized LDL in Relation to Intima-Media Thickness in Carotid and Femoral Arteries in 58-Year-Old Subjectively Clinically Healthy Men

“…The interobserver variations for IMT have been shown to be satisfactory. 32 The present analysis used the average of measurements of IMT from the left and right common carotid arteries (common carotid artery and carotid bulb).…”