The Potential of Radiolabeled Bisphosphonates in SPECT and PET for Bone Imaging

Skeletal-related events due to bone metastases can be prevented by early diagnosis using radiological or nuclear imaging techniques. Nuclear medicine techniques such as Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) have been used for diagnostic imaging of bone for decades. Although it is widely recognized that conventional diagnostic imaging techniques such as Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) have high sensitivity, low cost and wide availability, the specificity of both techniques is rather low compared to nuclear medicine techniques. Nuclear medicine techniques, on the other hand, have improved specificity when introduced as a hybrid imaging modality, as they can combine physiological and anatomical information. Two main radiopharmaceuticals are used in nuclear medicine: [^99mTc]-methyl diphosphonate ([^99mTc]Tc-MDP) from the generator and [¹⁸F]sodium fluoride ([¹⁸F]NaF) from the cyclotron. The former is used in SPECT imaging, while the latter is used in PET imaging. However, recent studies show that the role of radiolabeled bisphosphonates with gallium-68 (⁶⁸Ga) and fluorine-18 (¹⁸F) may have a potential role in the future. This review, therefore, presents and discusses the brief method for producing current and future potential radiopharmaceuticals for bone metastases.