Preparation and quality control of radiolabeled streptokinase for Thrombosis imaging

Background: in order to diagnose the site of thrombi, radiolabeled streptokinase can be prepared. the radiolabeled compound can be used in imaging of thrombi in many cardiovascular diseases. materials and methods: streptokinase was successively labeled with [^67ga]-gallium chloride using cyclic dtpa-dianhydride. the conjugation with dtpa was optimized for concentration, time and temperature followed by size exclusion chromatography using g-50 sephadex. the radiochemical purity of the tracer was checked using hplc and itlc methods. the biodistribution studies were performed in normal rats up to 167 h using tissue counting and preliminary spect studies up to 2 h. results: the radiolabeled enzyme was prepared in 60 minutes after incubation at room temperature, with the radiochemical purity of >95% (hplc) and >99% (itlc) methods. the radioactivity was accumulated in lung, intestine and liver as shown by scarification and spect (single photon emission computed tomography) methods. conclusion: radiolabeled streptokinase was prepared in suitable radiochemical purity and its biodistribution is comparable to other radiolabeled proteins. further studies are required to investigate the imaging properties of the tracer in appropriate animal model.