Comparative diagnostic accuracy of contrast-enhanced MRI and ¹⁸F-FDOPA PET-CT in recurrent glioma

Objectives: To compare the diagnostic accuracy of contrast enhanced magnetic resonance imaging (Ce-MRI) and ¹⁸F-fluorodopa ( ¹⁸F-FDOPA) positron emission tomography (PET)-computed tomography (CT) for detecting recurrent glioma. Methods: In this prospective study, 35 patients (age, 36.62 ± 0.86 years; 80 % male) with histopathologically proven glioma with clinical suspicion of recurrence were evaluated using Ce-MRI and ¹⁸F-FDOPA PET-CT. ¹⁸F-FDOPA PET-CT images were evaluated qualitatively and semi-quantitatively. Combination of clinical follow-up (minimum 1 year), repeat imaging and/or biopsy (when available) was taken as the reference standard. Results: Based on the reference standard, 26 patients were positive and nine were negative for recurrence. The sensitivity, specificity and accuracy of Ce-MRI were 92.3 %, 44.4 % and 80 % respectively, whereas those of ¹⁸F-FDOPA PET-CT were 100 %, 88.89 % and 97.1 % respectively. Results of Ce-MRI and ¹⁸F-FDOPA PET-CT were concordant in 74.3 % (29/35) and discordant in 17.1 % of patients (6/35). On McNemar analysis the difference was not statistically significant overall (P = 0.687), for high-grade tumour (P = 0.5) or low-grade tumours (P = 1.0). However, ¹⁸F-FDOPA PET-CT was more specific than Ce-MRI overall (P = 0.0002), for high-grade tumour (P = 0.006) and low-grade tumours (P = 0.004). Conclusion: F-FDOPA PET-CT shows a high but comparable diagnostic accuracy to Ce-MRI for the detection of recurrent glioma. However, it is more specific than Ce-MRI. Key Points: • Recurrent glioma in the postoperative site remains a diagnostic dilemma. • ¹⁸ F-FDOPA PET-CT shows high diagnostic accuracy for detecting recurrent glioma. • Diagnostic accuracies for ¹⁸ F-FDOPA PET-CT and contrast enhanced MRI are comparable. • However, ¹⁸ F-FDOPA PET-CT is more specific than Ce-MRI for recurrent glioma.