Fig 3.

Computer-simulated vessels: comparison of different matrix measurements. Graph shows differences in mean vessel measurements between the 512 matrix and the 256 and 256 ZIP matrices, with results for each observer shown separately. Error bars indicate the standard deviation of the measurements. Compared with the 512 matrix, both the 256 and 256 ZIP matrices consistently led to overestimation of the size of the vessel. With ZIP, however, a small but significant reduction in luminal diameter was observed for observers 1 and 2.