Abstract
1684
Objectives: Rationale: We investigated the relationship between 3-dimensional volumetric data assessed using magnetic resonance imaging (MRI) and 11C-labeled methionine (MET) positron emission tomography (PET) in patients with brain stem gliomas (BSG). Additionally, we explored on the prognostic value of the enhancement volume (EV)-to-metabolic tumor volume (MTV) ratio combined with oligodendroglial component presence and tumor grade in these patients.
Methods: Baseline brain 11C-MET PET and MRI scans were performed in 41 patients with BSG. Three-dimensional volumetric contrast enhancement data on post-gadolinium MRI, total tumor volume (TTV) on fluid attenuation inversion recovery MRI, and MTV on 11C-MET PET images were obtained. The relationships between the EV, MTV, and TTV were investigated, while the EV-to-MTV ratio was evaluated as a potential prognostic factor. Finally, the combined prognostic values of the EV-to-MTV ratio, oligodendroglial component, and tumor grading were assessed.
Results: The maximum standardized uptake volume (SUV) (p = 0.031), mean SUV (p = 0.026), and EV (p = 0.004) were significantly lower in BSGs with EV-to-MTV ratios ≤30%. In all 41 patients with BSG, the EV was significantly lower than the MTV (p < 0.001), while the TTV was significantly higher (p < 0.001). BSG patients with EV-to-MTV ratios ≤30% demonstrated a significantly better survival at 3 months (p = 0.015) and 12 months (p = 0.018) post-tumor resection compared to those with EV-to-MTV ratios >30%. Furthermore, using 30% as a threshold, the EV-to-MTV ratio was an independent prognostic factor for BSG patients (p = 0.009). When combined with histological features and tumor grading, the volumetric ratio stratified survival outcomes in BSG patients without oligodendroglial components (p = 0.006) and those with grade IV BSG (p = 0.025).
Conclusions: Patients with a lower EV-to-MTV ratio were more likely to achieve better prognoses than those with a higher ratio. Moreover, combining the EV-to-MTV ratio, histological grading, and oligodendroglial component can lead to improved prognostication of patients; however, this requires validation using a larger sample size.