Improved diagnostic accuracy for leptomeningeal dissemination in pediatric brain tumors using contrast-enhanced FLAIR imaging.

Background Central nervous system cancers are a leading cause of childhood cancer-related mortality. Accurate staging and assessment of leptomeningeal spread, particularly in aggressive neoplasms such as embryonal tumors, is crucial for treatment planning and prognosis. Conventional diagnostic methods, relying on magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) cytology, have limitations, including high false-negative rates and sensitivity issues. In this retrospective study, we aim to compare the diagnostic sensitivity of contrast-enhanced T2-weighted fluid-attenuated inversion recovery (CE-T2W-FLAIR) and 2D and 3D contrast-enhanced T1-weighted imaging (CE-T1WI) for detecting leptomeningeal disease. Methods We retrospectively reviewed 1372 MRI brain studies of 297 patients aged 1-19 years. We included only those MRI examinations adhering to our neuro-oncology protocol while excluding incomplete or suboptimal studies. A control group without leptomeningeal disease was matched for disease and age. Three groups of 2 neuroradiologists each, blinded to case status, reviewed the images using various sequences. The results were compared using the McNemar test and chi-squared test for P-values. Results The sensitivity of CE-T2W-FLAIR sequence was significantly higher compared with that of CE-T1WI (P = .025). There was no statistically significant difference between the sensitivity of 2D CE-T1WI and 3D CE-T1WI (P = .3173). The specificity of the 3D CE-T1WI was significantly lower compared with those of CE-T2W-FLAIR and 2D CE-T1WI (P = .014). The positive predictive values for CE-T2W-FLAIR, 2D CE-T1WI, and 3D CE-T1WI were 100%, 100%, and 68.4%, respectively, whereas the negative predictive values were 100%, 85.7%, and 85.71%, respectively. Conclusions The inclusion of CE-T2W-FLAIR in the MRI protocol improves sensitivity and specificity in diagnosing leptomeningeal spread in pediatric brain tumors.