99mTechnetium-HMPAO-labeled platelet scan in practice: Preparation, quality control, and biodistribution studies

There is no biodistribution or imaging data on (99m)Technetium (Tc)-hexarnethyl propylamine oxime (HMPAO)-labeled platelets in the literature. The current study aimed to present updated information about the clinical procedures for preparation and use of labeled platelets. Following two-step centrifugation at 1500 and 2500 rpm, the platelets were extracted from whole blood into platelet-rich plasma (PRP) above the buffy coat and then from PRP into a platelet pellet at the bottom of the tube. The Tc-99m-HMPAO-labeled platelets were inspected for purity, viability, release of( 99m)Tc from platelets, and sterility. Also, microscopic examination and thin layer chromatography (TLC) were performed. Biodistribution was assessed following necropsy in BALB/c mice and through imaging of New Zealand rabbits. The separation ratio was estimated at 98%, and radiochemical purity was measured to be 80%. The labeling efficiency was above 30% in more than half of the assays (range: 17-43%). The release of Tc-99m from platelets was 9% per hour at 37 degrees C. After 24 hours, stability was estimated at 54% in the human serum. The target organs of mice included the spleen and liver. In rabbits, the imaging results indicated liver as the target organ. Thyroid uptake was negligible up to 90 minutes. Based on the findings, extraction of platelets and labeling them with Tc-99m-HMPAO is a feasible and safe approach in routine practice.

Automated summary

This study provides updated information on the clinical procedures for preparation and use of labeled platelets. The labeled platelets were assessed for purity, viability, release of 99mTc, and sterility. Biodistribution was evaluated through necropsy in mice and imaging in rabbits. The findings suggest that the extraction and labeling of platelets with Tc-99m-HMPAO is a feasible and safe approach in routine practice.