Diagnostic ultrasound ( PDFDrive )

984 PART III Small Parts, Carotid Artery, and Peripheral Vessel Sonography
hrombus within the proximal GSV may be treated as a DVT
if within several centimeters of the insertion of the GSV, or more
than 5 cm long, according to physician preference. 65 If the
thrombus within the GSV extends into the CFV, it should be
treated as a DVT (Fig. 27.27, Video 27.12). If the top of the
thrombus is not seen in the CFV or external iliac vein, an IVC
and iliac vein examination should be considered to assess for
more central thrombus (Fig. 27.28, Video 27.13).
Residual (Chronic) Deep Venous Thrombosis
Diferentiation of acute from residual or chronic DVT with
imaging and clinical parameters is oten diicult. With compression
ultrasound, both acute and chronic DVT may show
noncompressibility of the vessel. Wall thickening and smaller
caliber vein suggest residual or chronic DVT (Fig. 27.29). Because
vein noncompressibility can be seen in both acute and chronic
DVT, an attempt to diferentiate the two is important for the
appropriate therapeutic decision. As the thrombus evolves, it
loses bulk and the vein may return to normal size or may become
smaller in caliber owing to scarring (Fig. 27.30, Video 27.14).
Residual thrombus will become broadly adherent to the
vein wall. Additional chronic indings that may assist in differentiating
chronic from acute DVT are echogenic weblike illing
defects within the vein (Fig. 27.31), collateral vessels (Fig. 27.32,
Video 27.15), and valvular damage with relux and subsequent
chronic deep venous insuiciency. 23 Diferentiation of acute
versus residual or chronic thrombus cannot be performed on
thrombus echogenicity alone, although if calciications are present,
there is at least an element of chronic thrombus present 87
(Fig. 27.33). If the thrombus is small (several centimeters
or less), measurement may be helpful to aid the clinician
in determining clinical importance, especially ater catheter
removal.
Potential Pitfalls
Lower extremity potential pitfalls to avoid include the
following:
1. Very slowly lowing blood may mimic the appearance of clot
(Fig. 27.34, Video 27.16 and Video 27.17); however, compression
will be normal.
A
B
C
FIG. 27.27 Great Saphenous Vein (GSV) Thrombus. Longitudinal
gray-scale (A) and color Doppler (B) images show thrombus within
the GSV (arrowheads) without extension into the common femoral
vein (CFV) (arrow). (C) In a different patient, longitudinal image shows
nonocclusive slightly mobile thrombus within the GSV (*) with extension
into the CFV (arrow). See also Video 27.12.