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Power Doppler US: Evaluation of the Morphology of Stenoses with a Flow Phantom¹

¹ From the Department of Radiology, Hôpital de Brabois, Rue du Morvan, 54511 Vandoeuvre les Nancy, France (M.C.); the Departments of Technical Assistance (D.W.) and Statistics (S.B.), University of Nancy, France; and the Department of Research and Development, Advanced Technology Laboratories, Bothell, Wash (P.P.). From the 1999 RSNA scientific assembly. Received July 13, 1999; revision requested August 25; final revision received April 27, 2000; accepted May 22. Address correspondence to M.C. (e-mail: michel.claudon@wanadoo.fr).

View larger version (43K): [in a new window]   Figure 1. Block diagram of the experimental system. PC = personal computer.

View larger version (167K): [in a new window]   Figure 2. Sagittal power Doppler US image shows spectral waveforms obtained with the high-frequency transducer with the following settings: longitudinal view; insonation angle, 60°; peak systolic velocity, 1 m/sec; resistive index, 0.6; gain, 30%; pulse repetition frequency, 1,500 Hz; filter, low; and color versus echo priority, 100%.

View larger version (119K): [in a new window]   Figure 3a. Sagittal power Doppler US images show the effects of stepwise changes in gain on both feeding and stenotic vessels with the high-frequency transducer. Baseline settings are as follows: longitudinal view; insonation angle, 60°; peak systolic velocity, 1 m/sec; pulse repetition frequency, 1,500 Hz; filter, low; and color versus echo priority, 100%. Gain is increased from (a) 20% to (b) 40% and (c) 60%, which results in increasing apparent lumen of the stenotic and normal vessels from 0.30 and 0.65 cm to 0.36 and 0.79 cm and 0.53 and 0.93 cm, respectively.

View larger version (112K): [in a new window]   Figure 3b. Sagittal power Doppler US images show the effects of stepwise changes in gain on both feeding and stenotic vessels with the high-frequency transducer. Baseline settings are as follows: longitudinal view; insonation angle, 60°; peak systolic velocity, 1 m/sec; pulse repetition frequency, 1,500 Hz; filter, low; and color versus echo priority, 100%. Gain is increased from (a) 20% to (b) 40% and (c) 60%, which results in increasing apparent lumen of the stenotic and normal vessels from 0.30 and 0.65 cm to 0.36 and 0.79 cm and 0.53 and 0.93 cm, respectively.

View larger version (104K): [in a new window]   Figure 3c. Sagittal power Doppler US images show the effects of stepwise changes in gain on both feeding and stenotic vessels with the high-frequency transducer. Baseline settings are as follows: longitudinal view; insonation angle, 60°; peak systolic velocity, 1 m/sec; pulse repetition frequency, 1,500 Hz; filter, low; and color versus echo priority, 100%. Gain is increased from (a) 20% to (b) 40% and (c) 60%, which results in increasing apparent lumen of the stenotic and normal vessels from 0.30 and 0.65 cm to 0.36 and 0.79 cm and 0.53 and 0.93 cm, respectively.

View larger version (150K): [in a new window]   Figure 4a. Transverse power Doppler US images show the effects of pulse repetition frequency changes on feeding vessel measurement with the high-frequency transducer. Baseline settings are as follows: transverse view; insonation angle, 40°; peak systolic velocity, 1 m/sec; gain, 30%; filter, low; and color versus echo priority, 100%. Pulse repetition frequency is increased from (a) 500 Hz to (b) 1,000 Hz, (c) 3,000 Hz, and (d) 6,000 Hz, which results in marked decrease in display of flow within the apparent lumen of the normal vessel.

View larger version (149K): [in a new window]   Figure 4b. Transverse power Doppler US images show the effects of pulse repetition frequency changes on feeding vessel measurement with the high-frequency transducer. Baseline settings are as follows: transverse view; insonation angle, 40°; peak systolic velocity, 1 m/sec; gain, 30%; filter, low; and color versus echo priority, 100%. Pulse repetition frequency is increased from (a) 500 Hz to (b) 1,000 Hz, (c) 3,000 Hz, and (d) 6,000 Hz, which results in marked decrease in display of flow within the apparent lumen of the normal vessel.

View larger version (153K): [in a new window]   Figure 4c. Transverse power Doppler US images show the effects of pulse repetition frequency changes on feeding vessel measurement with the high-frequency transducer. Baseline settings are as follows: transverse view; insonation angle, 40°; peak systolic velocity, 1 m/sec; gain, 30%; filter, low; and color versus echo priority, 100%. Pulse repetition frequency is increased from (a) 500 Hz to (b) 1,000 Hz, (c) 3,000 Hz, and (d) 6,000 Hz, which results in marked decrease in display of flow within the apparent lumen of the normal vessel.

View larger version (152K): [in a new window]   Figure 4d. Transverse power Doppler US images show the effects of pulse repetition frequency changes on feeding vessel measurement with the high-frequency transducer. Baseline settings are as follows: transverse view; insonation angle, 40°; peak systolic velocity, 1 m/sec; gain, 30%; filter, low; and color versus echo priority, 100%. Pulse repetition frequency is increased from (a) 500 Hz to (b) 1,000 Hz, (c) 3,000 Hz, and (d) 6,000 Hz, which results in marked decrease in display of flow within the apparent lumen of the normal vessel.

View larger version (126K): [in a new window]   Figure 5a. Sagittal power Doppler US images show the effects of filter stepwise changes on both feeding and stenotic vessels with the low-frequency transducer. Baseline settings are as follows: longitudinal view; insonation angle, 60°; peak systolic velocity, 2 m/sec; gain, 60%, pulse repetition frequency, 1,500 Hz; and color versus echo priority, 100%. The filter is increased from (a) low to (b) medium and (c) maximum, which results in considerable reduction in signal in the feeding vessel.

View larger version (135K): [in a new window]   Figure 5b. Sagittal power Doppler US images show the effects of filter stepwise changes on both feeding and stenotic vessels with the low-frequency transducer. Baseline settings are as follows: longitudinal view; insonation angle, 60°; peak systolic velocity, 2 m/sec; gain, 60%, pulse repetition frequency, 1,500 Hz; and color versus echo priority, 100%. The filter is increased from (a) low to (b) medium and (c) maximum, which results in considerable reduction in signal in the feeding vessel.

View larger version (132K): [in a new window]   Figure 5c. Sagittal power Doppler US images show the effects of filter stepwise changes on both feeding and stenotic vessels with the low-frequency transducer. Baseline settings are as follows: longitudinal view; insonation angle, 60°; peak systolic velocity, 2 m/sec; gain, 60%, pulse repetition frequency, 1,500 Hz; and color versus echo priority, 100%. The filter is increased from (a) low to (b) medium and (c) maximum, which results in considerable reduction in signal in the feeding vessel.

View larger version (24K): [in a new window]   Figure 6a. Graphs show results obtained with the high-frequency transducer. Baseline instrument settings are as follows: gain, 30%; pulse repetition frequency, 1,500 Hz; filter, low; color versus echo priority, 100%; and insonation angle, 60°. The reference diameters of the feeding vessel (DO = 0.84 cm) and stenotic vessel (do = 0.24 cm) are represented on each graph as dashed and dotted lines, respectively. Variations of measurement of the diameter of the feeding vessel (bold line) and the diameter of the stenotic vessel (lighter line) are represented when one of the following settings was changed: (a) gain, (b) pulse repetition frequency (PRF), and (c) filter for the longitudinal view, peak systolic velocity of 1 m/sec (); longitudinal view, peak systolic velocity of 2 m/sec (); and transverse view, peak systolic velocity of 1 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° (|).

View larger version (23K): [in a new window]   Figure 6b. Graphs show results obtained with the high-frequency transducer. Baseline instrument settings are as follows: gain, 30%; pulse repetition frequency, 1,500 Hz; filter, low; color versus echo priority, 100%; and insonation angle, 60°. The reference diameters of the feeding vessel (DO = 0.84 cm) and stenotic vessel (do = 0.24 cm) are represented on each graph as dashed and dotted lines, respectively. Variations of measurement of the diameter of the feeding vessel (bold line) and the diameter of the stenotic vessel (lighter line) are represented when one of the following settings was changed: (a) gain, (b) pulse repetition frequency (PRF), and (c) filter for the longitudinal view, peak systolic velocity of 1 m/sec (); longitudinal view, peak systolic velocity of 2 m/sec (); and transverse view, peak systolic velocity of 1 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° (|).

View larger version (22K): [in a new window]   Figure 6c. Graphs show results obtained with the high-frequency transducer. Baseline instrument settings are as follows: gain, 30%; pulse repetition frequency, 1,500 Hz; filter, low; color versus echo priority, 100%; and insonation angle, 60°. The reference diameters of the feeding vessel (DO = 0.84 cm) and stenotic vessel (do = 0.24 cm) are represented on each graph as dashed and dotted lines, respectively. Variations of measurement of the diameter of the feeding vessel (bold line) and the diameter of the stenotic vessel (lighter line) are represented when one of the following settings was changed: (a) gain, (b) pulse repetition frequency (PRF), and (c) filter for the longitudinal view, peak systolic velocity of 1 m/sec (); longitudinal view, peak systolic velocity of 2 m/sec (); and transverse view, peak systolic velocity of 1 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° (|).

View larger version (21K): [in a new window]   Figure 6d. Graphs show results obtained with the high-frequency transducer. Baseline instrument settings are as follows: gain, 30%; pulse repetition frequency, 1,500 Hz; filter, low; color versus echo priority, 100%; and insonation angle, 60°. The reference diameters of the feeding vessel (DO = 0.84 cm) and stenotic vessel (do = 0.24 cm) are represented on each graph as dashed and dotted lines, respectively. Variations of measurement of the diameter of the feeding vessel (bold line) and the diameter of the stenotic vessel (lighter line) are represented when one of the following settings was changed: (a) gain, (b) pulse repetition frequency (PRF), and (c) filter for the longitudinal view, peak systolic velocity of 1 m/sec (); longitudinal view, peak systolic velocity of 2 m/sec (); and transverse view, peak systolic velocity of 1 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° (|).

View larger version (18K): [in a new window]   Figure 7a. Graphs show results obtained with the low-frequency transducer. Baseline instrument settings are as follows: gain, 60%; pulse repetition frequency, 1,500 Hz; filter, low; color versus echo priority, 100%; and insonation angle, 60°. The reference diameters of the feeding vessel (DO = 0.84 cm) and stenotic vessel (do = 0.24 cm) are represented on each graph as dashed and dotted lines, respectively. Variations of measurement of the diameter of the feeding vessel (bold line) and the diameter of the stenotic vessel (lighter line) 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 measurement data of the diameter of the normal vessel from the transverse view have been excluded.

View larger version (25K): [in a new window]   Figure 7b. Graphs show results obtained with the low-frequency transducer. Baseline instrument settings are as follows: gain, 60%; pulse repetition frequency, 1,500 Hz; filter, low; color versus echo priority, 100%; and insonation angle, 60°. The reference diameters of the feeding vessel (DO = 0.84 cm) and stenotic vessel (do = 0.24 cm) are represented on each graph as dashed and dotted lines, respectively. Variations of measurement of the diameter of the feeding vessel (bold line) and the diameter of the stenotic vessel (lighter line) 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 measurement data of the diameter of the normal vessel from the transverse view have been excluded.

View larger version (24K): [in a new window]   Figure 7c. Graphs show results obtained with the low-frequency transducer. Baseline instrument settings are as follows: gain, 60%; pulse repetition frequency, 1,500 Hz; filter, low; color versus echo priority, 100%; and insonation angle, 60°. The reference diameters of the feeding vessel (DO = 0.84 cm) and stenotic vessel (do = 0.24 cm) are represented on each graph as dashed and dotted lines, respectively. Variations of measurement of the diameter of the feeding vessel (bold line) and the diameter of the stenotic vessel (lighter line) 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 measurement data of the diameter of the normal vessel from the transverse view have been excluded.

View larger version (24K): [in a new window]   Figure 7d. Graphs show results obtained with the low-frequency transducer. Baseline instrument settings are as follows: gain, 60%; pulse repetition frequency, 1,500 Hz; filter, low; color versus echo priority, 100%; and insonation angle, 60°. The reference diameters of the feeding vessel (DO = 0.84 cm) and stenotic vessel (do = 0.24 cm) are represented on each graph as dashed and dotted lines, respectively. Variations of measurement of the diameter of the feeding vessel (bold line) and the diameter of the stenotic vessel (lighter line) 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 measurement data of the diameter of the normal vessel from the transverse view have been excluded.

View larger version (21K): [in a new window]   Figure 8a. 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.

View larger version (25K): [in a new window]   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.

View larger version (23K): [in a new window]   Figure 8c. 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.

View larger version (22K): [in a new window]   Figure 8d. 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.