Contrast venography vs. radionuclide venography: a study of discrepancies and their possible significance.

In 51 instances, patients underwent radionuclide venography with technetium 99m-labeled macroaggregated albumin followed by contrast venography. The criteria used for diagnosis of a positive radionuclide venogram (flow pattern and retention of radionuclide) were evaluated. Cases in which there were discrepancies between the two studies were analyzed. Multiple factors were found to result in a lack of correlation between the two studies. These are: failure to recognize nonfilling of the deep venous system on the radionuclide venogram, disparate distribution of the venographic imaging agents, presence of varicose veins, large venous valves, previous femoral venipuncture, postsurgical narrowing with obstruction, age of the thrombus, and other factors. These factors and their implications with respect to venographic technique are discussed.