PET/CT in the assessment of previously treated skull base malignancies

Background. Altered anatomy, radiotherapy, hardware, and reconstructive materials distort the posttreatment ventral skull base. The diagnostic characteristics of positron emission tomography/CT (PET/CT) studies in those with suspected recurrent malignancy were assessed. Methods. A retrospective review was undertaken of patients with head and neck cancer who had PET/CT for ventral skull base disease. Results. Thirty-four PET/CTs were performed for suspected recurrent malignancy in the skull base (mean age, 59.6 ± 10.7 years; female 38%). The group comprised mainly minor salivary (35.3%), squamous (32.3%), and neuroectodermal (23.6%) tumors. Mean clinical follow-up after PET/CT was 256 ± 173 days. Sensitivity was 100% but specificity was 40%. Standard uptake values (SUVs) for true positives were higher than for those without disease (p = .03). Conclusions. PET/CT is a highly sensitive test for malignant disease. The mucosal lining of the reconstructed skull base is a common source for inflammatory pathologies that may lead to false-positive PET/CT. Defining SUV thresholds for malignancy may improve specificity.