Stereology: a simplified and more time-efficient method than planimetry for the quantitative analysis of vascular structures in different models of intimal thickening

ObjectiveSemiautomatic computer-assisted planimetry is currently the standard morphometric technique in models of intimal thickening. We evaluated stereological point counting as an alternative method for the measurement of cross-sectional vascular areas (lumen, intima, and media) by comparing precision, efficiency, and variance components.MethodsSections from murine atherosclerotic aorta (n=21), stented rabbit iliac arteries (n=30), and porcine coronary arteries (n=30) were analyzed at two institutes using both techniques. To determine reproducibility, porcine arteries were measured twice.ResultsArea measurements showed almost identical means and standard deviations for planimetry and stereology [e.g., intima (mm2): 0.10±0.11 vs. 0.12±0.12 (mouse), 0.60±0.16 vs. 0.60±0.15 (rabbit), and 1.92±1.52 vs. 1.97±1.61 (pig)]. Deming regression and Bland–Altman plots demonstrated a good agreement between both techniques that was not influenced by artery size. Both methods exhibited excellent repeatability, although planimetry (−0.18±0.27) was more precise than stereology (−0.17±0.47; variance, P<.01, Levene test). In addition, intraoperator variance (error inherent to the technique) was greater for stereology (1.6–15.8% vs. 4.8–33.5%), whereas interoperator variance (error between institutes) was very small for both methods (0.1–0.9% vs. 0.1–1.7%). Indeed, biologic variability was, by far, the most important variance component in all measurements (84–98% vs. 65–95%). Finally, stereology required 20% (mouse; P<.05) to 40% (pig; P<.001) less time to complete analysis.ConclusionThe quantification of vascular structures by planimetry and stereology yielded comparable results in all models of intimal thickening, but stereology proved to be less time-consuming. Therefore, study design may dictate the most appropriate choice of technique.