FIG 1. MR images of a child with left middle cerebral artery ischemia and sickle cell disease.

A, Transaxial FLAIR (10002/172/1) image obtained with the child under propofol anesthesia has hyperintense signal abnormality in the basal cisterns.

B, Similar abnormal hyperintense signal is seen in the subarachnoid spaces bilaterally in the convexity region of this same patient.

C, Follow-up transaxial FLAIR (10002/172/1) image shows resolution of the signal abnormality in the basal cisterns. Chloral hydrate was administered, and patient's retainer was not removed, creating the paranasal sinus artifact that was not present on the previous study.

D, Resolution of the abnormal signal intensity in the convexity subarachnoid spaces is also noted on the follow-up image obtained with the child under chloral hydrate sedation.