Feasibility Study of Computed High b-Value Diffusion-Weighted Magnetic Resonance Imaging for Pediatric Posterior Fossa Tumors

Abstract

Purpose: To evaluate the diagnostic efficacy of computed diffusion-weighted imaging (DWI) in pediatric posterior fossa tumors generated using high b-values. Methods: We retrospectively performed our study on 32 pediatric patients who had undergone brain magnetic resonance imaging for a posterior fossa tumor between January 2016 and January 2022. The DWIs were evaluated for each patient by two blinded radiologists. The computed DWI (cDWI) was mathematically derived using a mono-exponential model from images with b = 0 and 1,000 s/mm(2) and high b-values of 1,500, 2,000, 3,000, and 5,000 s/mm(2). The posterior fossa tumors were divided into two groups, low grade and high grade, and the tumor/thalamus signal intensity (SI) ratios were compared. The Mann-Whitney U test and receiver operating characteristic (ROC) curves were used to compare the diagnostic performance of the acquired DWI (DWI1000), apparent diffusion coefficient (ADC)(1000) maps, and cDWI (cDWI1500, cDWI(2000), cDWI(3000), and cDWI(5000)). Results: The comparison of the two tumor groups revealed that the tumor/thalamus SI ratio on the DWI1000 and cDWI (cDWI1500, cDWI(2000), cDWI(3000), and cDWI(5000)) was statistically significantly higher in high-grade tumors (P < 0.001). In the ROC curve analysis, higher sensitivity and specificity were detected in the cDWI1500, cDWI(2000), cDWI(3000), and ADC(1000) maps (100%, 90.90%) compared with the DWI1000 (80%, 81.80%). cDWI(3000) had the highest area under the curve (AUC) value compared with other parameters (AUC: 0.976). Conclusion: cDWI generated using high b-values was successful in differentiating between low-grade and high-grade posterior fossa tumors without increasing imaging time.