AIMS OF THE COLOGNE-SYMPOSIUM ON RADIOLABELLED PLATELETS In 1976, M. Thakur et al (1) were the first to publish a paper concerning the in vivo thrombus detection with 111- In-labelled platelets. Previous attempts at scintigraphic thrombus localisation had been disappointing because of the unspecific binding of a number of the isotopes used, as well as the poor labelling efficiency or an insufficient low gamma-emitting property. Because of its physical characteristics (2.8 days half-life, 94% gamma emission) 111 Indium turned out to be the best isotope for platelet kinetic studies as well as for the measurement of platelet incorporation by Thrombi to be used up until now. The lipophile complexes of Ill-In (8-hydroxyquinoline, acetylacetone, tropolone) diffuse passively into the platelets without altering the function or the life span of the platelets. This advantage has let to an increase in the clinical applications of 1211-In labelled platelets. Today, radiolabelled platelets are used for thrombus detection in several different medical areas such as cardiology, nephrology. angiology or neurology. Even though many scientists and hospital doctors now routinely use radiolabelled platelet as a diagnostic tool, there is as yet not a standardized labelling method. In addition to this, there are neither standardized image procedures for the different clinical applications nor an agreement about specificity and sensitivity of the method. In 1983, a symposium on Radiolabelled Cellular Blood Elements was organized by M.Thakur, M.R.Hardeman and M.D.

Platelet Labelling Techniques.- Thromboembolism and radiolabelled platelets.- Platelet isolation technique and viability testing.- Imaging thrombus with radiolabelled monoclonal antibody to platelets.- Haemodilution improves 111In platelet labelling efficiency.- Tc99m HMPAO as a potential platelet labelling compound: first in vivo and in vitro results.- Platelet labelling with 111In tropolonate.- Radiolabelled Platelets in Cardiology.- Radiolabelled platelets in cardiovascular diseases.- Dual isotope subtraction platelet scintigraphy in the diagnosis of left ventricular thrombosis.- Failure of Sulfinpyrazone to prevent left ventricular thrombosis in patients with acute myocardial infarction treated with oral anticoagulants; A randomized trial in 100 patients.- Cardiac Indium111 platelet scintigraphy in stroke patients.- Monitoring of Antiplatelet Therapy.- Monitoring of antithrombotic therapy with radiolabelled platelets.- Use of Dual isotope platelet scintigraphy for monitoring antiplatelet therapy in stroke patients.- The evaluation of a new specif ic Thromboxane A2 antagonist on radiolabelled platelet disposition in prosthetic grafts.- Platelet Scintigraphy in Stroke Patients.- Platelet scintigraphy in stroke patients.- Indium111 platelet scintigraphy in symptomatic and asymptomatic caritid artery disease. Preliminary findings of a prospective study.- Radiolabelled platelet interactions with the damaged endothelium in the carotid artery of rabbits.- Healing following carotid endarterectomy measured by 111ln platelet uptake.- Tc99m labelled autologous platelets as screening in patients with cerebrovascular disease.- Platelet Scintigraphy in Angiology.- Indium111 labelled platelet imaging of prosthetic materials in Humans.- Scintigraphy of platelet adherence in processed dermal sheep collagen [PDSC] grafts.- Radiolabelled platelet deposition predicts pseudointimal hyperplasia in arterial prostheses.- Hematology and Other Clinical Applications.- 111Indium labelled platelets in thrombocytopenic purpura. Survival and radiodistribution studies with a scintillation camera.- Use of 111In fragmented platelets in the detection of occult sepsis.- The clinical utility of Indium111 labelled platelet scintigraphy in the diagnosis of renal transplant rejection.- Platelet labelling with 111In Merc. Usefulness in renal transplantation.