Potential utility of bone scan in cranial bone flap osteomyelitis Abstract Objective Currently, the diagnosis of bone flap osteomyelitis (BFO) remains a challenge for medical imaging. The present study aimed to identify predictive scintigraphic patterns of BFO. Methods This retrospective study reviewed planar bone scan of patients with suspected BFO between 2010, and 2016. A total of 15 patients were included. Final diagnosis of BFO was obtained by histological and bacteriological documentation. Eight scintigraphic signs potentially helpful were reviewed and correlated with the final diagnosis individually or in combination through Fischer exact test. Results Eight patients out of 15 (53.3%) were diagnosed with BFO. Radionuclide uptake inside the bone flap during blood-pool phase was predictive for BFO (p = 0.007) with 75.0% sensitivity 100% specificity, and 86.7% accuracy. In combination, radionuclide uptake inside the bone flap or a spreading wavefront between blood-pool and delayed phases was associated with BFO (p = 0.007). It did not improve diagnostic performance. Conclusion Using well-defined and reproducible scintigraphic signs, bone scan is helpful for the diagnosis of BFO.