How accurate is 18F-FDG-PET-CT in determining local cartilaginous/bony involvement by head & neck malignancy?

Results PET-CT scans demonstrated increased abnormal osseous uptake in 63 cases, of which 52 were true osseous invasion, but 11 were false-positive (4 due to osteoradionecrosis, 4 benign dental infection/inflammation, 3 over-staging due to intense FDG-uptake nearby the bone). 708 cases were reported as ‘no osseous uptake’, of which 704 were truenegative, but 4 were false-negative (2 due to intrinsically low FDG-avid primary disease and bony lesions were not significantly FDG-avid, 2 due to bony necrosis of tumour with no significant FDG-uptake). Sensitivity, specificity, PPV, NPV and accuracy of PET-CT in detecting local osseous invasion are 93, 98, 83, 99 and 98% respectively. Conclusion 18F-FDG-PET-CT plays an important role in detecting local osseous invasion by HNC, with an accuracy of 98%. Important false-positives are due to benign causes such as infection and osteoradionecrosis, and due to intense FDG-uptake nearby the bone. If there is clinical doubt further investigations including MRI and biopsy should be performed.