Clinical evaluation of a technetium-99m bone imaging agent based on the vicinal diphosphonate 1,2-diphosphonoethyleneglycol (DPEG)

From a series of technetium-99m labelled agents based on a vicinal diphosphonic acid structure, the ligand 1,2-diphosphonoethyleneglycol (DPEG) was selected for clinical study on the basis of a biodistribution in rats which compared well with that of methylene disphonphonate (MDP). The 99Tcm-DPEG agent was assessed in ten patients in whom bone metastases had been demonstrated by 99Tcm-MDP imaging two to seven days previously. Visual comparison of the skeletal images obtained with the two agents revealed the same number of bone metastases at the same locations. Statistical analysis of the data revealed no significant differences between the two radiopharmaceuticals on the basis of lesion to soft tissue ratio and lesion to normal bone ratio, although a slightly higher lesion to soft tissue ratio was found for MDP than for DPEG (p less than 0.03). At least for the formulation tested, it is concluded that this new radiopharmaceutical based on the P-C-C-P structure does not possess diagnostic advantages over 99Tcm-MDP for the detection of bone metastases.