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Proper diagnosis of venous system disease often requires both functional and anatomic information about the venous circulation. Functional tests such as the maximum venous outflow (MVO), the venous refilling time (VRT), and the calf muscle pump ejection fraction (MPEF) (see Chapter 9) are extremely useful as measures of whole leg or regional venous function but can detect only regionally significant reflux or a significant impediment to venous outflow. Anatomic imaging of the venous system does not assess overall hemodynamic function but can detect even very small amounts of local and regional reflux and can visualize both obstructing and nonobstructing thrombus.
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Successful imaging of the deep venous system requires a thorough knowledge of venous anatomy and physiology, as well as meticulous attention to detail. The most useful modalities available for venous imaging are contrast venography, magnetic resonance imaging (MRI), and most importantly, Duplex ultrasound, which has become the “gold standard” of venous imaging (Table 10-1).1–3 Superficial venous imaging can be performed by modern duplex ultrasound with resolution as clear as 1 mm. A detailed protocol for its use is described in this chapter.
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Nonultrasound Radiologic Procedures
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Many techniques have been employed historically to evaluate the venous system. As technology improves, the development of less-invasive techniques has come to surpass previously employed invasive techniques. An understanding of the history of venous imaging is important to the physician treating venous disease.
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Contrast venography is neither absolutely sensitive nor specific in the diagnosis of venous pathology, but prior to the introduction of duplex ultrasound, it was the standard to which all other diagnostic tests were compared. It is no longer the standard and is reviewed here to give historical perspective. Duplex ultrasound has replaced contrast venography in the vast majority of clinical situations.
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Deep and superficial venous thrombosis and venous insufficiency may be evaluated by contrast venography, although deep venous visualization is typically intended. Digital subtraction venography can be performed for even more superb images. Superficial veins and varices are imaged by direct injection of a radiopaque contrast material into the veins of interest. After a tourniquet is placed around the lower leg in order to occlude the superficial, but not the deep, veins, contrast material is injected into a superficial dorsal foot vein. The contrast passes through perforating veins into the deep venous system. Thrombus appears either as a filling defect outlined by contrast or as a “cutoff” lesion stopping the flow of contrast (Figure 10-1). Reflux is detected when contrast flows backward through failed valves into a more ...