Incremental Role of Spinal Diffusion-Weighted Imaging in the Detection of Leptomeningeal Metastasis for Pediatric Intracranial Malignancies: Results from a Prospective Study

Screening for leptomeningeal disease (LMD) in pediatric brain tumors on the magnetic resonance imaging protocol is often limited by artifacts, making diagnosis challenging. To prospectively evaluate the incremental role of diffusion-weighted imaging (DWI) in screening of LMD in pediatric brain tumors. This prospective study included pediatric patients with primary brain tumors having a propensity for cerebrospinal fluid (CSF) metastasis. The spine was screened with T2-weighted (T2W), DWI, and post-contrast T1W (T1W PC) sequences, and LMD was confirmed with CSF analysis and follow-up. The study included 69 patients. LMD was positive in 27 patients and 105 lesions. Smooth LMD was detected in 18 patients on T1W PC. Out of 85 nodular LMD lesions, 81 were detected on DWI. Six lesions on the T1W PC and 16 on T2W were false positives (artifacts). The sensitivity and specificity were: for T1W PC: 93 and 86%; T2W: 63 and 62%; and for DWI: 63 and 100%. The combined sensitivity, specificity, positive predictive value, and negative predictive value of all three sequences were 93, 100, 100, and 95%. The T1W PC sequence is the most reliable sequence for detecting LMD. Using DWI in conjunction with T1W PC and T2W excludes artifacts, resulting in a higher specificity.