Pilot Prospective Evaluation of 99mTc-MDP Scintigraphy, 18F NaF PET/CT, 18F FDG PET/CT and Whole-Body MRI for Detection of Skeletal Metastases

Objective: The aim of this study was to compare Tc-99m-MDP bone scanning, F-18 NaF PET/CT, F-18 FDG PET/CT, and whole-body MRI (WBMRI) for detection of known osseous metastases. Patients and Methods: This prospective pilot trial (September 2007-April 2009) enrolled 10 participants (5 men, 5 women, 47-81 years old) diagnosed with cancer and known osseous metastases. F-18 NaF PET/CT, F-18 FDG PET/CT, and WBMRI were performed within 1 month for each participant. Results: The image quality and evaluation of extent of disease were superior by F-18 NaF PET/CT compared to Tc-99m-MDP scintigraphy in all patients with skeletal lesions and compared to F-18 FDG PET/CT in 3 of the patients with skeletal metastases. F-18 NaF PET/CT showed osseous metastases where F-18 FDG PET/CT was negative in another 3 participants. Extraskeletal metastases were identified by F-18 FDG PET/CT in 6 participants. WBMRI with the combination of iterative decomposition of water and fat with echo asymmetry and leastsquares estimation, short tau inversion recovery, and diffusion-weighted imaging pulse sequences showed fewer lesions than F-18 NaF PET/CT in 5 patients, same number of lesions in 2 patients, and more lesions in 1 patient. WBMRI showed fewer lesions than F-18 FDG in 3 patients and same lesions in 6 patients. Conclusions: Our pilot phase prospective trial demonstrated superior image quality and evaluation of skeletal disease extent with F-18 NaF PET/CT compared to Tc-99m-MDP scintigraphy and F-18 FDGPET/CT, as well as the feasibility of multisequence WBMRI. In addition, F-18 FDG PET/CT provided valuable soft-tissue information that can change disease management. Further evaluation of these findings using the recently introduced PET/MRI scanners is warranted.