Hyperintense Cerebrospinal Fluid on FLAIR Images Induced by Ventilation with 100% Oxygen

Abstract

To investigate in a prospective randomized study setting if increased signal intensity of the cerebrospinal fluid (CSF) on fast FLAIR images is caused by high oxygen concentrations or anesthetic agents used during general anesthesia. 40 children (13 females/27 males) aged 3 months to 8 years were included. The study was approved by the ethics committee of the authors' institution. Parents gave written informed consent to participation of their children. Patients were randomly allocated to one of four different anesthesia techniques: sevoflurane plus 30% oxygen, sevoflurane plus 100% oxygen, propofol plus 30% oxygen, and propofol plus 100% oxygen. Hard copies of the FLAIR sequence were used for blinded analysis of the signal intensity of the subarachnoid space. No significant difference in signal intensity of the CSF was detected between anesthesia with propofol or sevoflurane irrespective of using 30% or 100% oxygen during anesthesia. On the other hand, signal intensity of the CSF was increased when sevoflurane or propofol was combined with 100% inhaled oxygen. The difference of the CSF signal intensity was most pronounced over the cerebral convexities (p < 0.005) but was also observed in the basal cisterns. Hyperintense signal in the subarachnoid space can result from supplemental oxygen during anesthesia. To avoid misdiagnosis such as subarachnoid hemorrhage, purulent meningitis or meningeal carcinomatosis, radiologists should be aware of the phenomenon of increased cerebrospinal fluid signal intensity on T2-weighted FLAIR images caused by supplemented oxygen.