Direct scintigraphic imaging of pulmonary embolism

Lung perfusion scan for indirect embolus imaging using sup(99m)Tc-labeled particles is a simple non-invasive method with high sensitivity but low specificity. If combined with 133Xe-ventilation study the specificity is significantly enhanced. However, a definite diagnosis would be possible only by direct visualisation of the embolus. Additionally, a successful labeling of a suitable tracer like fibrinogen, platelets, leucocytes or plasmin with sup(99m)Tc, 123I or 111In would allow one to discover also the source of the embolus in one examination. The limiting factors for clinical application are still high costs and technical problems with the label technique. Our preliminary results show encouraging results with 111Indium labeled platelets but more extensive clinical trials are necessary