Diagnostic ultrasound ( PDFDrive )

CHAPTER 27 Peripheral Vessels 969
to measure narrowing of the vessel, and velocity and waveform
criteria are more widely applied. Color Doppler improves the
examination by rapidly depicting areas of turbulent or highvelocity
low that can be further sampled by spectral Doppler
for velocity characterization.
he main criteria for characterizing arterial stenosis involve
waveform morphology, PSV, and end-diastolic velocity (EDV).
For velocity criteria, the absolute values and the peak velocity
ratio (deined as peak velocity at or in the downstream jet
divided by peak velocity of the artery 2 cm upstream) have both
been applied efectively. In a study of 338 arterial segments,
focal increase in the PSV ratio at the stenosis relative to the
adjacent nonstenotic artery exceeding 2.0 is consistent with
at least 50% diameter stenosis when combined with spectral
broadening and loss of transient low reversal in the artery 10
(Fig. 27.9). he distal artery waveform will be abnormal with
tardus parvus waveforms in the setting of stenosis greater than
50% (Fig. 27.10) but is typically normal if a lesser degree of
stenosis is present. 10 Direct measurement of PSVs can also be
performed. For the femoral-popliteal region of native vessels, a
combination of thresholds of PSV greater than 200 cm/sec and
ratio above 2 : 1 have been suggested as criteria for greater than
70% stenosis with sensitivity of 79% and speciicity of 99% 11
(Fig. 27.11).
FIG. 27.5 Occlusion of the Supericial Femoral Artery With a
Large Collateral Exiting Proximal to the Occlusion (Arrow). The
presence of a collateral suggests chronic occlusion. See also Video 27.2.
FIG. 27.6 Common Femoral Artery Stenosis. Color and spectral
Doppler shows normal biphasic waveform, with ill-in of the waveform
spectral envelope, indicating some degree of stenosis but less than
50%.
A
B
FIG. 27.7 Focal High-Grade Stenosis in the Proximal Supericial Femoral Artery (SFA). (A) Elevated peak systolic velocity at a focal
high-grade stenosis in the proximal SFA. (B) Tardus parvus pattern downstream.