MRI Signs for the Preoperative Diagnosis of Intracranial Solitary Fibrous Tumors.
BACKGROUND Intracranial solitary fibrous tumors (ISFTs) are frequently misdiagnosed as meningiomas on MRI. Existing MRI signs have been evaluated individually, without a standardized and externally validated diagnostic framework. PURPOSE To develop and validate an MRI-based diagnostic score for intracranial solitary fibrous tumors (ISFT-DS) for the preoperative identification of ISFTs. STUDY TYPE Retrospective multicenter diagnostic accuracy study. POPULATION Five hundred with ISFTs (mean age, 46.4 ± 11.7 years; 269 men), 250 with low-grade meningiomas (mean age, 57.0 ± 11.1 years; 51 men), and 250 with high-grade meningiomas (mean age, 49.6 ± 14.3 years; 108 men). The development and external validation cohorts included 840 (84%) and 160 (16%) patients, respectively. FIELDSTRENGTH/SEQUENCE Spin-echo T1-weighted imaging (T1WI), fast or turbo spin-echo T2-weighted imaging, and contrast-enhanced spin-echo T1-weighted imaging. ASSESSMENT Three potential MRI features-T1WI hyperintensity, honeycomb-like cystic change, and trans-compartmental growth pattern-were assessed by three neuroradiologists and combined into the 0-3-point ISFT-DS. Diagnostic performance and the effects of standardized training in six readers were evaluated. STATISTICAL TESTS Sensitivity, specificity, accuracy, kappa statistics, receiver operating characteristic analysis, DeLong tests, χ2and Fisher exact tests, analysis of variance, McNemar test, Kruskal-Wallis tests. p < 0.05 indicated statistical significance. RESULTS At an ISFT-DS cutoff of ≥ 1, sensitivity/specificity were 81.4%/83.3% in the development cohort and 76.3%/86.3% in the external validation cohort, respectively. Specificity reached 98.3%/98.8% at ≥ 2 and 100%/100% at 3. Interreader agreement was good to excellent for the three MRI features and the ISFT-DS (κ = 0.80-0.87). Standardized reader training on the ISFT-DS increased the overall AUC from 0.67 to 0.80 (ΔAUC = 0.13), with larger gains for Readers 1 and 2 (ΔAUC = 0.21 and 0.15, respectively). DATA CONCLUSION The ISFT-DS provides a reproducible and teachable MRI-based scoring system for standardized preoperative identification of ISFTs. EVIDENCE LEVEL 3. TECHNICAL EFFICACY Stage 2.