Abstract
Platelets pretinned with a neutral Sn(II)-2-mercaptopyridme-
N-oxide (SN-MPO) were labeled with
99mTc and compared to those labeled with
99mTc-HMPAO. The conditions of labeling platelets, e.g. concentrations of platelets and Sn(II)-MPO,
99mTc in ACD-saline or ACD-plasma media, pH and incubation time, were optimized using canine platelets. Moderate labeling efficiency was obtained with 20 μg of tin(II) chloride and 30 min incubation with Sn-MPO and pertechnetate. The viability of labeled platelets was determined by platelet recovery and platelet survival times in Beagle dogs. The labeling efficiency with platelets from 43 mL of blood was 62.8 ± 7.6%. The platelet recovery was 35.7 ± 5.0% and exponential survival time was 34.6 ± 3.1 h compared to 43.3 ± 12.0% and 29.5 ± 3.3 h for
99mTc-HMPAO-labeled platelets. These values were significantly (
P < 0.01) lower than
111In-labeled platelets. Biodistribution in dogs indicates lower retention in blood, spleen and liver after some initial
99mTc excretion in urine. The platelet deposition with
99mTc platelets (Sn-MPO method) on polyurethane angio-catheters was similar to
99mTc-HMPAO-labeled platelets. This study indicates that the platelets could be successfully labeled with pertechnetate in a cost-effective manner for the evaluation of thromboembolic complications.