Page 229 - Libro 2

PART 4 • PERIPHERAL VENOUS
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Duplex Imaging of the Lower Extremity Venous System
Steven R. Talbot and Mark Oliver
OBJECTIVES
Describe the components of the lower extremity venous system
Define the normal image and the Doppler characteristics of the venous system
Identify the image characteristics consistent with acute and chronic thrombus
Describe the Doppler waveform characteristics associated with various pathologies
List the risk factors associated with the formation of a deep vein thrombus
KEY TERMS
acute thrombus | chronic thrombus | deep vein | perforating vein | superficial vein | valve
GLOSSARY
acute thrombus newly formed clotted blood within a vein; generally less than 14 days old
chronic thrombus clotted blood within a vein that has generally been present for a period of several weeks or months
deep vein a vein that is the companion vessel
to an artery and travels within the deep muscular compartments of the leg
perforating vein a small vein that connects the deep and superficial venous systems; a vein that
Before the advances in ultrasound imaging that made it possible to use duplex ultrasound to look at the veins of the legs and the arms, diagnosing ve- nous thrombosis was a complicated matter. Clinical judgment was inaccurate. The diagnostic study of choice was venography, which was painful, expen- sive, and carried its own set of risks.
In the 1980s, the advent of venous duplex ultra- sound imaging changed all that. Since that time, duplex ultrasound imaging has become the method
passes between the deep and superficial compart- ments of the leg
superficial vein a vein that is superior to the muscular compartments of the leg; travels within superficial fascia compartments; has no corre- sponding companion artery
valve an inward projection of the intimal layer of a vein wall producing two semilunar leaflets that present the retrograde movement of blood flow
of choice for imaging deep vein thrombosis (DVT).1 Occasionally, other imaging modalities may be used for difficult or limited duplex ultrasound examina- tions.2 Duplex ultrasound has the capability to diag- nose, localize, and determine the age of a thrombus as well as follow the natural course of disease. Thus, it has become a mainstay in the management of DVT.3 In addition, duplex ultrasound has the capabil- ity of discovering and diagnosing vascular and non- vascular incidental findings during the examination.4
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