Objective Bone is considered as the third most common site of metastases, besides lung and liver. Early detection of skeletal metastases aids in better management of skeletal-related events. In the present study cold kit-based 2,2ʹ,2ʹʹ-(10-(2-((diphosphonomethyl)amino)-2-oxoethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl) triacetic acid (BPAMD) was labeled with ⁶⁸Ga. The radiolabeling parameters and clinical evaluation in patients with suspected bone metastases were compared with routinely used ^99mTc-methylenediphosphonate (^99mTc-MDP).
Methodology The kit components of MDP were incubated with ^99mTcO−₄ at room temperature for 10 min, followed by radiochemical purity testing using thin-layer chromatography. For radiolabeling of BPAMD, the cold kit components reconstituted in 400 μL of HPLC grade water were transferred and incubated with ⁶⁸GaCl₃ in the reactor vessel of the fluidic module at 95°C for 20 min. Radiochemical yield and purity were determined with instant thin-layer chromatography using 0.5 M sodium citrate as mobile phase. For clinical evaluation, patients (n = 10) with suspected bone metastases were enrolled. ^99mTc-MDP and ⁶⁸Ga-BPAMD scans were performed on two different days in random order. Imaging outcomes were noted and compared.
Results Radiolabeling of both tracers is facile using cold kit, although BPAMD requires heating. The radiochemical purity was observed to be greater than 99% for all preparations. Both MDP and BPAMD detected skeletal lesions; however, additional lesions were detected in total of seven patients which were not visualized clearly on ^99mTc-MDP scan.
Conclusion BPAMD can be easily tagged with ⁶⁸Ga using cold kits. The radiotracer is suitable and efficient for detection of bone metastases using PET/computed tomography.