Department of Neurology,
Barmbek Hospital,
Hamburg, Germany
To the Editor:
Steinke and coworkers1 recently reported on the possible
advantages of power Doppler imaging (PDI) for quantification of
stenoses of the internal carotid artery (ICA): similar to
angiography, it should be possible to assess the degree of
stenosis of the ICA as the percentage of the diameter reduction
from the longitudinal image.
We have tested this examination procedure by comparison with the usual,
validated sonography criteria on 40 cases of ICA stenosis.
Included in the observation period of the study were all consecutive
stenosis findings for which color-coded duplex sonography
(CCDS) fulfilled the following criteria: (1) detection of a local flow
acceleration in the ICA, (2) peak flow velocity of
In 22% of the cases an adequate evaluation by PDI was not possible: in
6 stenoses the residual lumen could not be demonstrated because
of sound extinction; in an additional 3 stenoses, the vessel
wall could not be imaged adequately for determination of the degree of
stenosis. In the remaining cases the degree of stenosis
was regularly underestimated in comparison with the Doppler
criteria (Figure 1
Department of Neurology,
Marien-Hospital,
Düsseldorf, Germany
Department of Neurology,
University Hospital Mannheim,
Mannheim, Germany
Department of Neurology,
AHEPA Hospital,
Thessaloniki, Greece
© 1998 American Heart Association, Inc.
Letters to the Editor
Evaluation of Carotid Artery Stenosis by Power Doppler Imaging
1 m/s (measurement
of the jet flow at the stenosis maximum or, in cases of sound
extinction there, directly distal from it), and (3) detection of flow
disturbances. Quantification was achieved using the known
Doppler criteria.2 
).
Figure 2
illustrates this for the example of a high-grade stenosis of
the ICA: the stenosis is very poorly demonstrated in the PDI
(panel A). Angiography and conventional CCDS findings with
determination of the peak