Fig 7. Pearson correlation between the mean carotid stenosis narrowest diameter (mm) and the mean cross-sectional VT stenosis area (mm²). There was excellent correlation between the 2 stenosis quantification measures at 0.88 (n = 176). This supports the use of the narrowest diameter measurement to quantify carotid bulb stenosis, in lieu of the more precise cross-sectional area measurement. A regression curve was plotted over the data with an R² value of 0.76, which indicates that the narrowest diameter has an excellent predictive ability to estimate the cross-sectional area (as defined by the VT).