68Ga-Ca-phytate particles: A potential lung perfusion agent of synthetic origin prepared in a cold kit format.
The objective of this study was to investigate the radiosynthesis of68Ga-Ca-phytate particles and then characterize the formulation for radiochemical purity, radioactive particle size distribution, and biodistribution in normal rats. This radiotracer was prepared using a commercial phytate cold kit after reconstitution with saline,68Ga-chloride generator eluent, calcium chloride, and air, then heating at 100°C for 30 minutes to achieve 99% radiochemical purity of68Ga-particles that were 21% 3-5 μm, 8% 5-15 μm, and 71% >15 μm in diameter. This optimal formulation was stable for 2 hours at room temperature. Intravenous administration of68Ga-particles in rats resulted in an uptake of 93% in the lungs, 4% in the liver plus spleen, and 3% in the carcass after 20 minutes. Two-thirds of the carcass activity was radioactive blood, likely to be68Ga-transferrin. The positron emission tomography image was superior than the99mTc-MAA image because it displayed high lung uptake against a low background. Low uptake by the liver, spleen did not interfere with the diagnostic quality, and faint activity in the submandibular (salivary) glands was due to68Ga-transferrin. The preclinical data so far indicate that68Ga-Ca-phytate particles have good potential as a lung perfusion imaging agent.
Nuclear Medicine Department, RAH Radiopharmacy, Royal Adelaide Hospital, Adelaide, SA, Australia.
William
W
Hsieh
Nuclear Medicine Department, RAH Radiopharmacy, Royal Adelaide Hospital, Adelaide, SA, Australia.
Masood
M
Ali
Nuclear Medicine Department, RAH Radiopharmacy, Royal Adelaide Hospital, Adelaide, SA, Australia.
Renee
R
Praehofer
Nuclear Medicine Department, RAH Radiopharmacy, Royal Adelaide Hospital, Adelaide, SA, Australia. chris.tsopelas@health.sa.gov.au.
Chris
C
Tsopelas
D000818:Animals; D002122:Calcium Chloride / Q000737:chemistry*; D005260:Female; D005710:Gallium Radioisotopes / Q000737:chemistry*; D008168:Lung / Q000098:blood supply* / Q000000981:diagnostic imaging*; D055420:Perfusion Imaging / Q000379:methods*; D010833:Phytic Acid / Q000138:chemical synthesis / Q000737:chemistry*; D011854:Radiochemistry / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013696:Temperature
D005710:Gallium Radioisotopes; D010833:Phytic Acid; D002122:Calcium Chloride
Gallium-68; calcium phytate; cold kit; lung perfusion; particles