Radionuclide venography as an adjunct to V-P imaging in the assessment of thromboembolic disease

Ascending radionuclide venography, in principle, differs from radiographic contrast venography in that the radionuclide technique demonstrates flow patterns rather than anatomy. Normally the injection of the radiotracer into foot veins using the technique described results in the radioactivity passing into the deep venous system at its first opportunity, especially if care is taken to properly occlude the superficial venous system just below the knee. Radionuclide venography is more of a screening test and its relationship to contrast venography is the same as ventilation-perfusion imaging to contrast pulmonary arteriography. That is to say, just as when the V-P study does not satisfactorily answer the question regarding the presence of pulmonary embolism, contrast pulmonary arteriography is done, and contrast venography can be performed if the radionuclide venogram is not conclusive. In the patient with strong suspicion of deep venous thrombosis, the integrated VP-RNV is the best screening test. Considerable evolution in the technique of venography has occurred. Excellent studies are obtained using gamma cameras integrated with moving tables. The technique described depends upon the manipulation of venous flow in the lower extremity to demonstrate the deep venous system as well as possible