Automated measurement of intima-media thickness of carotid arteries in ultrasonography by computer software (original) (raw)
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B-mode ultrasonography is a diagnostic method which allows measurement of intima-media thickness (IMT) at the level of the carotid artery and femoral artery. The relationship between the common carotid artery (CCA) IMT and coronary artery disease, the changes in the IMT after drug therapy and its relation with heart attack and sudden death risk, the association between the IMT and systemic diseases mainly diabetes mellitus, hypercholesterolemia and hyperten-sion all had been investigated by many researchers (1-6). As pointed out by the collected data to date, measurement of IMT by ultrasonography has become a morphological criterion for the detection of atherosclero-sis. Manual measurement methods are generally used to measure the IMT values sonographically but results show variations secondary to subjective parameters when manual measurement methods are employed (7). Additionally studies have demonstrated that CCA IMT values may show interobserver variability in repeated measurements (8, 9). To decrease the interobserver variability during the IMT measurements computer software programs were developed which allow automated measurements. The aim of this study is to determine whether a correlation exists between the manual and computer assisted IMT measurements of CCA. Materials and methods A total of 88 patients were included the study which consisted of 39 males and 49 females (mean age, 37.7 years) who were referred for ultra-sonographic IMT analysis of the carotid artery. The study was conducted between January 2004 and June 2004 and consisted of selected cases from the archives in which the cases were either part of various studies conducted to measure IMT thickness in situations where IMT thickness were expected to increase or were normal cases which formed the control groups of these studies. Ultrasonographic images of the right and the left CCA of each case at the lower 1/3 cervical region proximally and 1 cm above the carotid bulb distally in longitudinal plane were obtained digitally and archived in the PACS system utilizing a sonography device with a high definition L12-5 linear wide band probe (Philips HDI 5000, Both-ell, WA, USA). Care was taken to keep the frequency level and other imaging parameters (general 2D optimization, low persistency) the same in each patient. Archived images were analyzed retrospectively in a blinded fashion by two investigators using a PACS workstation separately. CCA IMT measurements of the proximal and distal CCA posterior wall were done manually by the provided distance measurement system of the sonography device after magnification of the images (Figure 1). The two investigators measuring manually used the grading method from the ARIC (atherosclerosis risk in community) study and three measurements were made in a non-neighboring fashion within an approximately 1 cm PURPOSE Intima-media thickness (IMT) has been proposed to be a morphological criterion of atherosclerosis. The purpose of this study was to investigate the inter-observer variability of manual and also of computer software measurements of IMT. MATERIALS AND METHODS High-resolution common carotid artery (CCA) images of 88 patients that have been obtained by a linear broadband L5-12 MHz transducer and archived in PACS were retrospectively evaluated. Two separate investigators, who were unaware of the former results , evaluated the same images by using computer software that had a dedicated tool for automatic measurement of IMT. The results of the investigators were compared. RESULTS According to the two investigators who have performed manual measurements, mean values of IMT of right CCA were 0.6396 mm and 0.6356 mm; of the left CCA were 0.6662 mm and 0.6575 mm, respectively. The interobserver variability of measurements revealed the mean IMT as 0.6071 mm and 0.6048 mm for the right, 0.6216 mm and 0.6227 mm for the left CCA. Manual measurements of both investigators were found to be higher than the automatic measurements and the differences were statistically significant. Interobserver correlation of manual measurements was between 0.80-0.88 and of the automated measurements was between 0.93-0.98. CONCLUSION Manual measurements reveal higher values than the automated measurements of IMT. The interobserver correlation of automated measurements is higher than manual measurements. The use of dedicated software may be proposed to reduce the measurement errors.
Folia morphologica, 2003
The intima-media thickness (IMT) of carotid arteries was demonstrated to be a reliable measure for early stages of atherosclerosis. B-mode ultrasound may be used to measure carotid IMT. The measurements of the IMT of the carotid artery (CA) conducted by different investigators can be comparable and enable the implementation of clinical trial successfully while maintaining a high reproducibility value. The objective of the study was to evaluate the reproducibility of the measurements made by the same investigator on two separate occasions (intraobserver variability) and the reproducibility of the off-line measurements between four sonographers in our laboratory (interobserver variability). The IMT of CA in 25 subjects (15 post stroke and 10 healthy persons) was investigated with the use of high-resolution ultrasonography. The CA subdivided into the common, bulbs and internal segments were scanned twice with a 3-week interval. Additionally three other readers with different levels of ...
13th IEEE International Conference on BioInformatics and BioEngineering, 2013
The intima-media thickness (IMT) of the common carotid artery (CCA) is an established indicator of cardiovascular disease (CVD). There have been reports about the difference between the left and the right sides of the CCA IMT and its importance when evaluated with various risk factors as well as their association with the risk of stroke. In this study, we use an automated system based on snakes, for segmenting the CCA and perform measurements of the IMT of the carotid artery and provide their differences between the left and right sides. The study was performed on 205 longitudinal-section ultrasound images acquired from 87 men and 118 women at a mean±SD age of 63±10.47 years, out of which 51 had cardiovascular symptoms. A cardiovascular expert manually measured the IMT on the left CCA side (mean±standard deviation = 0.79±0.21 mm) and the right CCA side (0.76±0.33 mm). The left and right IMT automated measurements were 0.70±0.15 mm and 0.66±0.15 mm, respectively. We found no statistical significant differences: 1) between the left and right IMT measurements, for both the manual and automated measurements, and 2) between the manual and automated measurements for both sides. These findings suggest that the measurement of the CCA IMT on one side only is enough (and this is in agreement with other studies), as well as automated measurements can be used.
Manual and automated media and intima thickness measurements of the common carotid artery
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2000
The intima-media thickness (IMT) of the common carotid artery (CCA) is widely used as an early indicator of the development of cardiovascular disease (CVD). It was proposed but not thoroughly investigated that the media layer (ML) thickness (MLT), its composition, and its texture may be indicative of cardiovascular risk and for differentiating between patients with high and low risk. In this study, we investigate an automated method for segmenting the ML and the intima layer (IL) and measurement of the MLT and the intima layer thickness (ILT) in ultrasound images of the CCA. The snakes segmentation method was used and was evaluated on 100 longitudinal ultrasound images acquired from asymptomatic subjects, against manual segmentation performed by a neurovascular expert. The mean ± standard deviation (sd) for the first and second sets of manual and the automated IMT, MLT, and ILT measurements were 0.71 ± 0.17 mm, 0.72 ± 0.17 mm, 0.67 ± 0.12 mm; 0.25 ± 0.12 mm, 0.27 ± 0.14 mm, 0.25 ± 0.11 mm; and 0.43 ± 0.10 mm, 0.44 ± 0.13 mm, and 0.42 ± 0.10 mm, respectively. There was overall no significant difference between the manual and the automated IMC, ML, and IL segmentation measurements. Therefore, the automated segmentation method proposed in this study may be used successfully in the measurement of the MLT and ILT complementing the manual measurements. MLT was also shown to increase with age (for both the manual and the automated measurements). Future research will incorporate the extraction of texture features from the segmented ML and IL bands, which may indicate the risk of future cardiovascular events. However, more work is needed for validating the proposed technique in a larger sample of subjects.
Media thickness measurement of the common carotid artery
2007
Abstract The intima-media thickness (IMT) of the common carotid artery (CCA) is widely used as an early indicator of the development of cardiovascular disease (CVD). It was proposed but not thoroughly investigated that the media thickness (MT), its composition and texture may be indicative for identifying the risk of stroke and differentiating between patients with high and low risk. In this study we present an automated method for segmentation of the media layer and measurement of its thickness in ultrasound images of the CCA.
Background and Purpose-The intima-media thickness (IMT) of extracranial carotid arteries determined by B-mode ultrasound is a measurable index of the presence of atherosclerosis. The ultrasonographic scan protocol and the scan reading techniques used until now to measure IMT are, however, time consuming and require the participation of specialized research centers. In this study we present a cross-sectional study of 963 patients attending the Enrica Grossi Paoletti Center in Milan, Italy, with the aim of assessing whether ultrasonographic measurements of carotid artery in routine clinical practice can yield the same results as those obtained with quantitative methods used until now in clinical trials. Methods-Maximum and mean maximum IMT of carotid arteries were assessed by B-mode ultrasound with the use of the electronic caliper of the machine in real time. Results-The intraobserver and interobserver variability of IMT of carotid arteries performed with the electronic caliper in real time was similar to that of quantitative processing of frozen images (coefficients of variation of intraobserver and interobserver mean maximum IMT measurements were 4.2% and 7.3%, respectively). Carotid artery IMT thus measured correlated with most of the known atherosclerosis risk factors and discriminated between patients with and without previous history of cardiovascular events. IMT was linearly related to the total number of vascular risk factors both in the whole group and after stratification of patients into 3 age classes.
American journal of hypertension, 2006
Carotid intima-media thickness (IMT), an indicator of atherosclerosis and coronary heart disease (CHD) is usually evaluated by eye measurement under B-scope carotid artery ultrasonography. However, the axial resolution of this system is >/=0.1 mm, which causes difficulties in respect to accuracy and reproducibility. We evaluated a newly developed B-scope carotid artery ultrasonography programmed by an innovative measurement software, Intimascope (Media Cross Co. Ltd., Tokyo, Japan), which measures IMT with 10 times higher axial resolution at an estimated scale of 0.01 mm. Intraobserver or interobserver coefficient of variation (CV) of the computer-based average IMT (aver-IMT) value and 3-point IMT value were much smaller than the corresponding value by conventional eye-measurement method (3-point value). We measured IMT of 427 asymptomatic subjects undergoing medical checkups (243 men and 184 women, 23 to 73 years of age). Although the mean values of aver-IMT and 3-point IMT of 4...
Vascular Health and Risk Management, 2009
The measurement of carotid intima-media thickness (cIMT) has been used as a marker of arterial wall disease. Manual measurements have been performed in most epidemiological studies, but, due to the introduction of new technologies, automated software has been increasingly used. This study aimed to compare manual versus automated cIMT measurements in common carotid (CC), bifurcation (BIF), and internal carotid (IC). Methods: Automated and manual cIMT measurements were performed online in 43 middle-aged females. Carotid segment measurements were compared by Bland-Altman plot and the variation and repeatability coefficients between observers were also determined for comparison. Results: The average timespan for manual measurements (57.30 s) were significantly higher than for automated measurements (2.52 s). There were no systematic errors between methods in any carotid segments. The variation coefficient was 5.54% to 6.34% for CC and BIF, 9.76% for IC, and absolute differences were 85% below 0.1 mm and 70% below 0.05 mm. Interobserver agreement showed no systematic error. The variation and the repeatability coefficients were better for the automated than manual measures. Conclusion: Although both methods are reliable for cIMT measurements, the automated technique allows faster evaluation with lesser variability for all carotid segments currently used in atherosclerosis research.