Background: 3,4-dihydroxy-6-[18F]-fluoro-L-phenylalanine (FDOPA) positron emission tomography (PET) can identify well low and high grade brain tumors. However, increased FDOPA uptake has been reported in non-tumoral brain lesions. The aim was to analyse FDOPA-PET in patients with non-tumoral brain lesions and to compare them with patients with (low and high grade) brain tumors.

Methods: retrospective analyse. Patients consecutively recruited with suspected primary brain tumor (based on clinical and MRI findings) referred for FDOPA-PET at Nimes university Hospital between June 2015 and June 2019. FDOPA-PET parameters (maximum and mean lesion standardized uptake values [SUV] and ratios comparing lesion with different background uptake SUV) and thresholds were analysed in search for those offering optimal discrimination between non-tumoral and tumoral lesions.

Inclusion Criteria:

• presence of defined tumor (histology was required) or non-tumor (diagnosed by histological or other analyses) diagnosis,
• clinical and MRI follow-up of >24 months,
• FDOPA-PET scan <2 months before surgery or stereotactic biopsy (when performed)

patients with suspected primary brain tumor (based on clinical and MRI findings) referred for FDOPA-PET in our centre between June 2015 and June 2019