The Hyperintense Acute Reperfusion Marker on Fluid-Attenuated Inversion Recovery Magnetic Resonance Imaging Is Caused by Gadolinium in the Cerebrospinal Fluid

Background and Purposes— The hyperintense acute reperfusion marker (HARM) on fluid-attenuated inversion recovery MRI is believed to be caused by gadolinium-based contrast agents crossing a disrupted blood–brain barrier. However, this hypothesis has never been directly verified in humans. Methods— In this study, we analyzed cerebrospinal fluid samples of patients with HARM on imaging regarding the presence and concentration of gadolinium-based contrast agents. Results— Gadobutrol was found in concentrations of approximately 50 &mgr;mol/L. Using phantom MRI experiments, we demonstrate that the detected concentrations are consistent with the observed HARM imaging pattern. Conclusions— Our study yields first direct evidence in humans that the imaging phenomenon HARM is indeed caused by leakage of gadolinium-based contrast agents into the cerebrospinal fluid.