Purpose: Many children with sarcomas undergo whole body 2-deoxy-2-(18F)fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) and technetium methylene diphosphonate (99Tc-MDP) studies. It is unknown whether the combination of both tests results in more accurate detection of bone lesions than 18F-FDG- PET/CT alone.
Methods: 99Tc-MDP bone and 18F-FDG PET/CT scans were each read by 2 “blinded” observers and then reviewed side-by-side by 3 readers. Bone lesions were graded qualitatively on a 5-point scale (from benign to malignant). Clinical and imaging follow-up (n=21) and bone biopsy results (n=8) served as reference standard.
Results: A total of 39 paired 99Tc-MDP and 18F-FDG-PET/CT studies (cases) performed at a mean interval 4±7 days, were performed on 29 patients (mean age 12±5 y). Of these, 21 patients (72%) had bone sarcoma, whereas 8 patients (28%) had soft tissue sarcoma. By patient and case-based analysis, 18F-FDG PET/CT had an accuracy of 100%. 99Tc-MDP had accuracies of 90% and 82% by patient and case-based analysis. The combined interpretation had an accuracy of 97%.
Conclusions: In this study, 99Tc-MDP bone imaging does not provide an added diagnostic value for bone involvement over 18F-FDG-PET/CT.