Diagnostic utility of fractional anisotropy in differentiating glioma grades

Objective: This study investigates the diagnostic potential of fractional anisotropy (FA), derived from diffusion tensor imaging (DTI),for distinguishing low-grade (grade 1–2) from high-grade (grade 3–4) gliomas by evaluating the tumor core, tumor margin, andperitumoral region.Patients and Methods: Sixty patients with histopathologically confirmed gliomas (grade 1–2, n=30; grade 3–4, n=30) underwentpreoperative 3T Magnetic Resonance Imaging (MRI) including DTI. FA was measured in the tumor core (solid component), tumormargin, peritumoral region, and contralateral normal-appearing white matter (NAWM). NAWM-normalized FA ratios were alsoevaluated. Groups were compared using independent-samples t tests, and diagnostic performance was evaluated with receiveroperating characteristic (ROC) analysis including AUC, optimal cut-off, sensitivity, and specificity.Results: Fractional anisotropy in tumor-related regions was lower than contralateral NAWM in both groups. Grade 3–4 gliomasshowed significantly lower raw FA in the tumor core, tumor margin, and peritumoral region, whereas NAWM FA did not differbetween groups. NAWM-normalized FA ratios were also significantly reduced in grade 3–4 gliomas (all p < 0.05). Tumor core raw FAshowed the highest discrimination (AUC = 0.842, 95% CI: 0.734–0.932, cut-off = 0.150, sensitivity = 0.80, specificity = 0.73).Conclusion: Raw and NAWM-normalized FA metrics, particularly in the tumor core and peritumoral region, differentiated grade 1–2from grade 3–4 gliomas and may serve as supportive noninvasive markers for preoperative grading.