Evolving role of NaF-PET in the Diagnosis and Treatment of Osteoporosis

Objectives: It is estimated that osteoporosis affects nearly 200 million people worldwide and accounts for almost 9 million fractures per year. While various treatments such as bisphosphonates are available for patients to lower risk of fracture, novel methods are required to assess treatment efficacy and its effects on bone metabolism. ¹⁸F-sodium fluoride positron emission tomography (NaF-PET) is an increasingly popular modality for the imaging of active calcium metabolism. Molecular imaging with PET using global quantitative techniques has been shown in other applications of progressive diseases to portray metabolic changes years before morphological changes are detectable using conventional modalities. Early diagnosis and monitored treatment of osteoporosis made possible by NaF-PET represent the potential to reduce long-term fracture rates in patients. This review will discuss applications of NaF-PET to characterize bone turnover in order to assess risk of osteoporosis as well as effects of therapy.

Methods: Methods of NaF Uptake Quantification to Assess Turnover 1. Measuring plasma clearance and bone uptake 2. Defining regions of interest (ROI) in the spine, femoral neck, and pelvis 3. Global assessment to evaluate whole body involvement

Results: Using NaF-PET to Evaluate Therapy for Osteoporosis 1. Effects of teriparatide treatment as determined by PET 2. Effects of bisphosphonate treatment as determined by PET 3. Evaluation of bisphosphonate-induced osteonecrosis of the jaw (BONJ)

Conclusion: As NaF-PET becomes more widely used to examine skeletal changes, novel methods of analysis are needed to take full advantage of this powerful modality. Preliminary studies have already demonstrated the need for further development, and sensitive techniques that provide robust indicators of changes in overall skeletal metabolism will prove to be the most reliable approach.