Diagnostic ultrasound ( PDFDrive )

CHAPTER 26 The Extracranial Cerebral Vessels 943
TABLE 26.3 Recommendations for Follow-Up Based on Ultrasound Assessment
ASYMPTOMATIC
SYMPTOMATIC
Heterogeneous Plaque
Homogeneous
Plaque
Heterogeneous Plaque
Homogeneous Plaque
1%-39% b 3 months ×2
(1%-50%) c Then 6 months
Then yearly
Medical prescription (Rx) a
40%-59% b 3 months ×2
Then every 6 months until
converted to
homogeneous or
degree of stenosis
increases
Medical Rx a
60%-79% b Refer to vascular
(50%-70%) c specialist d
Medical Rx a (Alternatively,
if no intervention,
follow-up every 3
months to assess
stability)
80%-99% b Refer to vascular specialist b
(>70%) c Medical Rx a
2-5 years depending
on degree of plaque
and other risk
factors
3 months ×2
Then 6 months
Then yearly
Medical therapy a
Yearly
3 months ×2
Medical Rx a Then every 6 months
until converted to
homogeneous or
degree of stenosis
increases
6-month follow-up ×2
for stability, then
annually
Medical Rx a
1-3 years depending on
degree of plaque and
other risk factors
Refer for evaluation for
other sources such as
cardioembolic disease or
neurovascular sources of
symptoms
6 months ×2
Then yearly
Medical Rx a
Medical Rx a
Refer to vascular Refer to vascular
specialist d
specialist d
Medical Rx a
Medical Rx a
(Alternatively, if no
intervention, follow-up
every 3 months to
assess stability)
a Medical Rx includes antiplatelet Rx, statin Rx, smoking cessation, and good blood pressure control.
b Bluth et al. criteria. 45
c SRU criteria. 122
d Vascular specialist could be a vascular surgeon, interventional cardiologist, or interventional neuroradiologist or neurosurgeon, depending on the
skill set of providers in any given area. Treatment recommended by these specialists could be endovascular stent, endarterectomy, or intensive
medical Rx.
incidence of CAS increased 149%. 192 While CAS has emerged
as a less-invasive treatment than CEA, several randomized clinical
trials and the Society of Vascular Surgery have shown CAS to
be associated with lower perioperative morbidity, particularly
myocardial infarction, but with an increased incidence of stroke. 193-
195
Careful patient selection is critical if the potential beneits of
carotid revascularization are to be realized. 193,194 Ultrasound may
be helpful in (1) assessing the presence and severity of stenosis;
(2) characterizing the carotid bifurcation; and (3) assessing
anatomic variants, vessel tortuosity, and plaque calciication before
stent placement (Fig. 26.38).
he role of ultrasound in determining patient selection also
remains controversial. Certainly, the accuracy of duplex ultrasound
in grading low-limiting stenosis is well established, with a
sensitivity of 94% and a speciicity of 92%, and is universally
accepted as an important criterion in patient selection. 193,194,196
However, although the role of plaque characterization in patient
selection remains controversial, it is becoming more important
as vulnerable plaque, as a cause of stroke, becomes more appreciated.
Vulnerable plaque appears to correlate with heterogeneous
or echolucent type 1 or 2 plaque. his type of plaque is associated
with intraplaque hemorrhage and is thought to have strong
embolic potential. Using intravascular ultrasound, Diethrich
et al. 197 showed a strong correlation between intravascular
ultrasound plaque characterization and histologic examination
of the plaque ater endarterectomy. Considering the accuracy of
ultrasound characterization, when intraplaque hemorrhage or
vulnerable plaque is identiied, CEA rather than CAS might be
the preferred method of revascularization to reduce the risk of
embolic complications. However, Reiter et al. 85 were unable to
use plaque echolucency as a criterion for those at increased risk
for post-CAS neurologic events and therefore did not recommend
this type of risk stratiication. he use of plaque characterization
to determine the type of therapeutic intervention needs further
assessment.
Grading Carotid Intrastent Restenosis
Sonography allows accurate evaluation of stent placement within
the carotid vessels. 198 Carotid stents are readily visualized with
ultrasound, allowing sonographers to assess disease before, along,