Positive and Negative Predictive Value of PET-CT in Skull Base Lesions: Case Series and Systematic Literature Review.

Objectives  To study positive (PPV) and negative predictive value (NPV) of positron emission tomography with computed tomography (PET-CT) scans in determining malignancy in skull base lesions and perform a systematic literature review for optimal PET-CT interpretation. Design  Retrospective case series and systematic literature review of the current English literature. Setting  Tertiary referral academic medical center. Participants  All patients with skull base lesions that underwent PET-CT and tissue biopsy from 2010 to 2013. Main Outcome Measures  PPV and NPV of radiologist's report and standardized uptake value (SUV) cutoff of 2.5 and 3, biopsy with pathologic interpretation, clinical follow-up. Results  A total of 31 PET-CT scans of 16 patients were studied; 10 PET-CT were performed upfront for diagnostic purposes and 21 were post-treatment surveillance scans. The PPV of radiologist's interpretation, SUV cutoff of 2.5, and SUV cutoff of 3.0 was 80%, 60%, and 68.4%, with a NPV of 100%, 83.3%, and 75%, respectively. Literature search yielded 500 abstracts; 7 studies met inclusion criteria for detailed review. No consensus or guidelines for optimal SUV cutoff value was found. Conclusions  PET-CT based on SUV cutoff criteria alone has high NPV but low PPV in determining malignancy in skull base lesions. Interpretation by a radiologist experienced in nuclear medicine and neuroradiology, synthesizing clinical, SUV, and radiologic data are of superior value.