Association between pretreatment 11C-methionine PET metrics, histology, and prognosis in 125 newly diagnosed adult diffuse glioma patients based on the WHO 2021 classification.

OBJECTIVE: To clarify the relationships between 11 C-methionine (MET) positron emission tomography (PET) metrics and the histology, genetics, and prognosis of adult-type diffuse glioma (ADG) based on the World Health Organization (WHO) 2021 classification.

METHODS: A total of 125 newly diagnosed ADG patients were enrolled. We compared the maximum standardized uptake value (SUVmax), tumor-to-normal ratio (TNR), metabolic tumor volume (MTV), and total lesion methionine uptake (TLMU) to the histology and genetics of the ADG patients. We also evaluated the prognoses of the 93 surgically treated patients.

RESULTS: The isocitrate dehydrogenase (IDH) wild (w) ADG patients showed significantly higher MET-PET metrics (p<0.05 for all parameters), significantly shorter overall survival (OS) and progression-free survival (PFS) (p<0.0001 for both) than those of the IDH mutant (m) ADG patients. In the IDHm ADG group, the SUVmax, MTV, and TLMU values were significantly higher in IDHm grade (G) 4 astrocytoma patients than IDHm G2/3 astrocytoma patients (p<0.05 for all), but not than G2-3 oligodendroglioma patients. The PFS was significantly shorter in the G4 astrocytoma patients versus the G2/3 astrocytoma and G3 oligodendroglioma patients (p<0.05 for both). The SUVmax and TNR values were significantly higher in recurrent patients than non-recurrent patients (p<0.01 for both), but no significant differences were found in MTV or TLMU values.

CONCLUSION: MET-PET metrics well reflect the histological subtype, WHO grade and prognosis of ADG based on the 2021 WHO classification, with the exception of oligodendroglial tumors. Volumetric parameters were not significantly associated with recurrence, unlike the SUVmax and TNR.