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Intracoronary ultrasound imaging: intraobserver and interobserver variability of morphometric measurements
D Hausmann1, A J Lundkvist, G J Friedrich
1Cardiovascular Research Institute, University of California at San Francisco 94143-0124.
Insights
Intracoronary ultrasound measurements of lumen and plaque dimensions show high agreement between observers and within observers. Derived parameters exhibit slightly higher variability, necessitating consideration in serial assessments.
Area of Science:
- Cardiovascular Imaging
- Interventional Cardiology
- Medical Imaging Analysis
Background:
- Intracoronary ultrasound (ICUS) imaging is crucial for assessing interventions and plaque burden.
- Accurate ICUS measurements are vital for evaluating treatment efficacy and disease progression.
- Inter- and intraobserver variability can impact the reliability of ICUS measurements.
Purpose of the Study:
- To evaluate the inter- and intraobserver variability of morphometric measurements from ICUS images.
- To assess the reliability of both qualitative and quantitative ICUS parameters.
- To determine the impact of variability on derived plaque and lumen dimensions.
Main Methods:
- 120 ICUS images from 87 patients were analyzed.
- Three independent observers performed measurements twice using computerized planimetry.
- Qualitative and quantitative parameters, including lumen dimensions and plaque characteristics, were assessed.
Main Results:
- High intraobserver and interobserver agreement was observed for qualitative parameters (>87%).
- Quantitative parameters like lumen area and diameters showed high correlation (r > 0.90) and low differences (<10%).
- Derived parameters (plaque area, stenosis) demonstrated slightly higher variability (r = 0.78-0.91, SD 20-30%).
Conclusions:
- Most qualitative and quantitative ICUS measurements exhibit low variability.
- Derived morphometric parameters may have slightly higher variability.
- Variability must be considered when comparing serial ICUS measurements.
Abstract:
Measurements of lumen and plaque dimensions by intracoronary ultrasound imaging are useful in assessing effects of intracoronary interventions and in quantifying plaque burden in transplant patients or during regression trials. However, these measurements are affected by inter- and intraobserver variability. In 87 patients, 120 intracoronary ultrasound images were obtained with a 4.3F, 30 MHz catheter. Morphometric measurements were performed two times by three independent observers using computerized planimetry. Intraobserver and interobserver agreement for qualitative parameters (presence of atherosclerotic plaque, calcified plaque, and residual nondiseased wall) was high (> 87%). For quantitative parameters measured directly in the images (lumen area, minimal and maximal lumen diameters, area within the internal elastic lamina, arc of calcium plaque) interobserver and intraobserver correlation between measurements was high (correlation coefficient r > 0.90) and differences between measurements were low (mean differences < 10%; SD < 20%). Measurement of the arc of nondiseased wall showed less interobserver correlation (r = 0.76 to 0.91), but percentages of difference between the measurements were low. Parameters derived from directly measured variables (plaque area, area stenosis, thickness, and eccentricity) showed slightly higher variability (correlations between measurements r = 0.78 to 0.91). SD for percentages of difference ranged between 20% and 30% (plaque area, area stenosis, and thickness) and systematic deviation between measurements (mean differences > 10%) occurred for plaque area. Thus most qualitative and quantitative measurements of lumen and plaque dimensions performed in intracoronary ultrasound images have low in intraobserver and interobserver variability; derived parameters may have slightly higher variability. Variability of morphometric measurements has to be considered, especially when serial ultrasound measurements are compared.