CAR T-cell therapy is a promising innovative therapy for hematological malignancies. Immune effectors cells-associated neurotoxicity syndrome (ICANS) is a significant complication of CAR therapy. The goal of this study is to understand what brain mechanisms become disrupted when patients experience ICANS. The study will test the hypothesis that cerebrospinal fluid catecholamines and multimodal magnetic resonance imaging are affected in this disorder. To test this hypothesis, the study will measure cerebrospinal fluid catecholamines in ICANS patients and evaluate brain magnetic resonance imaging for these participants. This study may contribute to knowledge about brain biomarkers and imaging of ICANS, which will greatly aid in ICANS detection and prevention.