Diagnostic ultrasound ( PDFDrive )

CHAPTER 26 The Extracranial Cerebral Vessels 947
A
B
C
FIG. 26.40 Long-Segment Stenosis of CCA Caused by
Takayasu Arteritis. Power Doppler images of (A) left and (B)
right CCA shows long-segment concentric narrowing caused by
greatly thickened walls of the artery (arrows). (C) Spectral Doppler
waveform shows a mildly tardus-parvus waveform.
Internal Carotid Artery Dissection: Spectrum
of Findings
INTERNAL CAROTID ARTERY
Absent low or occlusion
Echogenic intimal lap, with or without thrombus
Hypoechoic thrombus, with or without luminal narrowing
Normal appearance
COMMON CAROTID ARTERY
High-resistance waveform
Dampened low
Normal appearance
a high-resistance waveform. When the ICA is severely narrowed
(secondary to hemorrhage and a thrombus in the area of the
false lumen), low in the ICA may demonstrate high velocities.
In these nonoccluded ICA cases, low velocity waveforms in the
CCA may be normal. Although conventional angiography, MRA,
or CTA can be used initially to diagnose a dissection, ultrasound
can be used to follow patients to assess the therapeutic response
to anticoagulation. Repeat sonographic evaluation of patients
with ICA dissection ater anticoagulation therapy reveals recanalization
of the artery in as many as 70% of cases. 219-221 It is
important to consider the diagnosis of dissection as a cause of
neurologic symptoms, particularly when the clinical presentation,
age, and patient history are atypical for that of atherosclerotic
disease or hemorrhagic stroke.
Pulsatile Neck Masses in
the Carotid Region
he most common CCA aneurysm occurs in the region of the
carotid bifurcation. hese aneurysms may result from atherosclerosis,
infection, trauma, surgery, or contagious disease, such
as syphilis. he normal CCA usually measures no more than
1 cm in diameter. Carotid body tumors, one of several paragangliomas
that involve the head and neck, are usually benign,