INTRACORONARY ULTRASOUND IMAGING - INTRAOBSERVER AND INTEROBSERVER VARIABILITY OF MORPHOMETRIC MEASUREMENTS

Measurements of lumen and plaque dimensions by intracoronary ultrasoun d imaging are useful in assessing effects of intracoronary interventio ns and in quantifying plaque burden in transplant patients or during r egression trials. However, these measurements are affected by inter- a nd intraobserver variability. In 87 patients, 120 intracoronary ultras ound images were obtained with a 4.3F, 30 MHz catheter. Morphometric m easurements were performed two times by three independent observers us ing computerized planimetry. Intraobserver and interobserver agreement for qualitative parameters (presence of atherosclerotic plaque, calci fied plaque, and residual nondiseased wall) was high (>87%). For quant itative parameters measured directly in the images (lumen area, minima l and maximal lumen diameters, area within the internal elastic lamina , are of calcium plaque) interobserver and intraobserver correlation b etween measurements was high (correlation coefficient r > 0.90) and di fferences between measurements were low (mean differences <10%; SD <20 %). Measurement of the are of nondiseased wall showed less interobserv er correlation (r = 0.76 to 0.91), but percentages of difference betwe en the measurements were low. Parameters derived from directly measure d 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 de viation between measurements (mean differences >10%) occurred for plaq ue area. Thus most qualitative and quantitative measurements of lumen and plaque dimensions performed in intracoronary ultrasound images hav e low intraobserver and interobserver variability; derived parameters may have slightly higher variability. Variability of morphometric meas urements has to be considered, especially when serial ultrasound measu rements are compared.