Gold-195m: a steady-state imaging agent for venography that gives blood velocity measurement.

Gold-195m has found applications in first-pass studies for investigating both right and left ventricular activity as well as lung transit. Owing to its reasonably short half-life of 30 sec we have found it particularly useful for imaging leg veins up to and including the inferior vena cava. Its short half-life prevents recirculation activity from appearing, so continuous perfusion into a superficial foot vein and application of ankle tourniquets yield a steady-state image of the deep veins, with particularly good resolution. Its decay pattern along a vessel is very sensitive to blood velocity, so measurement of activity at various points on a vein in a computer static image can give velocity values that reveal abnormalities due to partial or complete thrombosis. The radiation dosimetry of 195mAu used in this way is lower than contrast and technetium-99m macroaggregated albumin [( 99mTc]MAA) venography, making it particularly useful for investigating deep vein thrombosis (DVT) in pregnancy.