Abstract
Introduction Susceptibility-weighted imaging (SWI) is a noninvasive MRI technique that detects microvascular features such as hemorrhage and neovascularization in brain tumors. Intratumoral susceptibility signals (ITSS) observed on SWI have been associated with tumor grade, particularly in gliomas. This study aimed to investigate the correlation between SWI-derived ITSS and tumor histological grades, and to evaluate the diagnostic performance of SWI in glioma grading. Materials and methods This retrospective single-center observational study included 44 adult patients (22 males, 22 females; mean age: 41.2 ± 18.5 years) with histologically confirmed glial tumors who underwent preoperative MRI with SWI between 2015 and 2020. ITSS were visually graded on SWI sequences as follows: Grade 0 (no ITSS), Grade 1 (1-5 foci), Grade 2 (6-10 foci), and Grade 3 (>10 foci). Grading was performed for both the entire tumor and the tumor center. Tumor grades were classified according to the 2021 WHO criteria as low-grade (Grades I-II) or high-grade (Grades III-IV). Statistical analysis included Mann-Whitney U, Kruskal-Wallis, and Spearman's correlation tests. Results ITSS was present in 34 patients (77.3%). Among ITSS-positive cases, 23 of 34 patients (67.6%) had high-grade gliomas, while 11 patients (32.3%) had low-grade gliomas. All ITSS-negative patients had low-grade gliomas. SWI grades showed a significant positive correlation with WHO tumor grades (r = 0.479, p = 0.001 for whole tumor; r = 0.461, p = 0.002 for tumor center). SWI grading differed significantly across WHO grades (p = 0.001). In whole-tumor evaluation, SWI achieved 74% sensitivity and 71% specificity for predicting high-grade gliomas. Tumor center evaluation yielded 65% sensitivity, 76% specificity, 75% positive predictive value (PPV), and 66% negative predictive value (NPV). ITSS-positive patients were significantly older than ITSS-negative patients (p = 0.001). Conclusions SWI-detected ITSS strongly correlates with glioma histopathological grade and patient age. Given its diagnostic performance, reproducibility, and contrast-free nature, SWI represents a valuable noninvasive tool for glioma grading and may be integrated into routine preoperative MRI protocols.