Timing and optimized acquisition parameters for the whole-body imaging of 177Lu-EDTMP toward performing bone pain palliation treatment

Objectives Lutetium-177-labeled ethylenediamine-N,N,N',N'-tetrakis (methylene phosphonic acid) (Lu-177-EDTMP), a beta-emitting bone-seeking therapeutic radiopharmaceutical being assessed as an agent for palliation of bone pain, can emit suitable gamma-photons for scintigraphy. This investigation sought to characterize its optimal conditions for whole-body gamma camera imaging in patients. Materials and methods Eleven patients with bone metastases underwent whole-body bone scanning using both Tc-99m-methyl-diphosphonate (Tc-99m-MDP) and Lu-177-EDTMP (29.4 +/- 12.5MBq/kg BW) utilizing a dual-head camera. For lutetium-177 imaging, two types of collimators, low-energy high-resolution (LEHR) and medium-energy general-purpose (MEGP), and two different peak energies of 113 and 208 keV were used. Results The femur-to-muscle uptake ratio (F/M) of Tc-99m-MDP was 2.69 +/- 1.06. For Lu-177-EDTMP, the significantly highest F/Ms were found at 24 h (12.59 +/- 5.73) and 48 h (12.54 +/- 5.23) by applying MEGP collimators and collecting the 208 keV photons. In all the combinations of collimator and peak energy, the F/Ms at 24 and 48 h are significantly higher than those at 1 h, except the combination of LEHR collimator and 208 keV peak energy. Lesion-to-normal bone uptake ratios of the Tc-99m-MDP bone scan and images at the 24 and the 48-h phases of Lu-177-EDTMP were analyzed. MEGP and 208 keV had significantly higher values in lesion-to-normal bone uptake ratios. The combination of LEHR and 208 keV provided the poorest images. Conclusion Lu-177-EDTMP can provide fine whole-body images with the best results when applying mediumenergy collimation and collecting the 208 keV energy photons and alternatively by collecting both 208 and 113 keV photons for higher count statistics. The most appropriate time point for imaging is around 24 h after injection. Nucl Med Commun 33:90-96 (C) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.