Figure 8b. Graphs show evaluation of the degree of stenosis. The reference degree of stenosis (SO; 71%) is represented as a dashed and dotted line. Variations of the estimated degree of stenosis 3.0 cm deep (lighter line) and 11.5 cm deep (bold line), calculated for each situation reported in Figures 6 and 7, are represented when one of the following settings was changed: (a) gain, (b) pulse repetition frequency (PRF), (c) and filter, for the longitudinal view, peak systolic velocity of 1 m/sec (
); longitudinal view, peak systolic velocity of 2 m/sec (
); transverse view, peak systolic velocity of 2 m/sec (x). (d) Gain setting was changed for the longitudinal view and peak systolic velocity of 2 m/sec for insonation angles of 40° (
), 60° (*), and 90° (|). Note that the estimation of degree of stenosis from the transverse view with the low-frequency transducer is not represented because measurement data of the diameter of the normal vessel have been excluded.