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[The diagnosis and imaging of the a. hepatica after orthoptic liver transplantation--a comparison of frequency-modulated and amplitude-modulated color Doppler sonography].

PURPOSE
We examined whether amplitude-modulated color Doppler (power Doppler) sonography provides a better anatomic imaging of the vascular course of the hepatic artery after liver transplantation.


PATIENTS AND METHODS
82 patients were examined with Doppler sonography after liver transplantation. The distal section of the hepatic artery was imaged both with frequency-modulated color Doppler (color Doppler) and power Doppler and a Doppler spectrum derived from each mode for determination of the flow velocity.


RESULTS
Native imaging of the hepatic artery was possible in 78/82 patients, in 2/82 patients only after administration of Levovist, and in 2/82 patients it could not be seen. In these two patients the diagnosis of hepatic artery occlusion was confirmed by angiography. The anatomic course was demonstrated more longitudinally by power Doppler than by color Doppler (p < 0.001; chi 2 test) which made the angle correction easier. A disadvantage of power Doppler was the lack of image contrast to the portal veins; thus evaluation of the vascular course in this section was better possible with color Doppler by means of a specifically generated aliasing in the flow of the hepatic artery (p < 0.001; chi 2 test). Determination of the flow velocity showed no significant differences between color and power Doppler supported duplex sonography.


CONCLUSIONS
The combined use of color Doppler and power Doppler improves visualization of the hepatic artery after liver transplantation. The lack of visualization of the vessel after administration of Levovist is diagnostic for occlusion of the vessel.