RESUMO
OBJECTIVE: To determine the most accurate morphometric approach to overcoming the obstacles of limited number, angle of section and irregular contours of vascular structures in analyzing vascular sections of renal biopsies. STUDY DESIGN: The luminal area of 451 cortical arterioles in 65 Masson-trichrome-stained renal sections was assessed with a computer-assisted imaging system connected to a Leica DMR microscope (Mikroskopie und Systeme GmbH, Wetzlar, Germany). The luminal area measured by the imaging system was used as the gold standard, against which three mathematical sector approaches and one classical approach were evaluated. The accuracy of these approaches was evaluated by means of the relative deviation from the measured value and of the degree of overestimation or underestimation. Intraobserver and interobserver variability were determined for the most accurate mathematical approach. RESULTS: As compared to measured luminal area, the sector elliptical approach yielded the lowest relative deviation (13.4 +/- 12.5%), without significant overestimation or underestimation (-0.6 +/- 18.3%). The intraobserver and interobserver correlation coefficients for this method were 82.3% and 86.5%, respectively. CONCLUSION: The sector elliptical approach is the most accurate mathematical approach to vascular sections in renal biopsies.
