Comparison of power Doppler and B-scan sonography for renal imaging using a sonographic contrast agent.
The goal of this study was to evaluate the relative performance of power Doppler and B-scan imaging modes in detecting vascular perfusion changes resulting from injection of a contrast agent. To allow this comparison the imaging plane and the contrast agent injection must be the same for both modes. We achieved this by using a rigid transducer holder and simultaneously recording power Doppler and B-scan images on separate videotapes. The kidneys of five adult beagles were scanned to allow a comparison of how power Doppler and B-scan imaging methods monitor changes during the injection of 0.1 ml/kg of a contrast agent, EchoGen emulsion (Sonus Pharmaceuticals, Bothell, WA). The changes in the images were assessed qualitatively by three radiologists and quantitatively using a custom-designed image analysis software. All of the radiologists agreed that no visually detectable changes occurred in B-scan images but that significant changes could be observed in power Doppler images. Image analysis also indicated a difference between power Doppler and B-scan images. The change in mean color level of power Doppler images could be displayed as an indicator dilution curve with a peak enhancement of 46 +/- 16 above the preinjection value. The time at which mean color level peaked was 18 +/- 13 s. The mean color level returned to half of the peak value by 69 +/- 42 s and returned to the preinjection baseline value by 148 +/- 73 s. Conversely, B-scan images showed statistically insignificant changes, and time measurements could not be made. By all measures used to evaluate images, power Doppler imaging had a greater sensitivity in detecting changes resulting from contrast agent injection than B-scan imaging. This finding indicates that power Doppler imaging of contrast agent injections can be used to map regional differences in flow as well as quantitative measurements of a contrast agent's transit time and has the potential to assess kidney abnormalities associated with renal blood flow.
Sehgal
C M
CM
Department of Radiology, University of Pennsylvania, Philadelphia, USA.
Arger
P H
PH
Pugh
C R
CR
Kirchofer
J I
JI
Kotlar
E Y
EY
Bovee
K C
KC
D000818:Animals; D003287:Contrast Media; D004285:Dogs; D005466:Fluorocarbons; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D007668:Kidney / Q000098:blood supply / Q000000981:diagnostic imaging*; D012039:Regional Blood Flow; D012680:Sensitivity and Specificity; D018608:Ultrasonography, Doppler; D010420:Pentanes
D003287:Contrast Media; D005466:Fluorocarbons; C008806:perfluoropentane; D010420:Pentanes