Relative insensitivity of densitometric stenosis measurement to lumen edge determination

Coronary artery stenosis measurement from coronary arteriograms is dependent on lumen edge determination. In theory, dependence may be minimized by densitometric integration of the entire lumen as compared with densitometric determination of edges alone coupled with calculation of lumen size by geometric formulas. To assess the impact of approximations of lumen border position when densitometric and geometric methods are employed, external, intermediate and internal borders were defined and used with each method to calculate lumen narrowing from images of contrast-filled, asymmetrically stenotic model vessels and from clinically generated coronary arteriograms. Actual cross-sectional area narrowing of models correlated almost perfectly with densitometric narrowing for each of the three border criteria (external: r = 0.99, n = 192; intermediate: r = 0.99, n = 192; internal: r = 0.99, n = 192). Lumen narrowing calculated by assuming a circular lumen geometry with a diameter equal to the distance between these identical borders correlated less well with true area narrowing (external: r = 0.79, n = 192; intermediate: r = 0.83, n = 192; internal: r = 0.78, n = 192); the residual variance of the densitometric regression was significantly less than that of the geometric regression for each of the three border criteria (external: 8.13 versus 372, p less than 0.001; intermediate: 7.39 versus 315, p less than 0.001; internal: 7.13 versus 531, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)