18F-FDG PET imaging for treatment response assessment and management guidance in patients with skull base osteomyelitis

Abstract

Objective The objective of this study is to evaluate the role of hybrid 18F-FDG PET for treatment response assessment and management guidance in patients with skull base osteomyelitis. Materials and methods Retrospectively, 33 patients, with at least a baseline and follow-up PET (computed tomography/MRI) scan, were included. Parameters like standardized uptake value (SUV) max, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) (initial, follow-up, percentage change) were analysed and outcomes based on 18F-FDG PET reports were classified into resolution (a), partial response (b), progression (c) and stable disease (d). The clinical course and response on anatomical imaging were also compared with 18F-FDG PET. Results There was mild correlation between initial SUV with ESR (0.338) and CRP (0.384). Moderate correlation was seen between follow-up SUV and CRP (0.619), percentage change in SUV max (PC SUV) with percentage change in ESR (0.456) and CRP (0.668). Mean PC SUV was 70% (a), 35% (b), −40% (c) and −18% (d), respectively. 48% (16/33) (resolution, progression, stable disease) patients had clear management change with 18F-FDG PET with either escalation or stopping of antibiotics/antifungals. Management decision in partial response group (52%, 17/33) was taken clinically. On retrospective PC SUV analysis, treatment continuation group (8 patients) showed 20% decrease, whereas the group that was only monitored further (9 patients) had 48% reduction in SUV. Conclusion 18F-FDG PET showed a moderate association with clinical markers used in follow-up of patients with skull base osteomyelitis and is a reliable investigation for assessment of disease status. This can be used as a guide along with clinical evaluation for de-escalation of treatment.