Artifact simulating subarachnoid and XXXX on single-shot, fast spin-echo fluid-attenuated inversion recovery images caused by head movement: A trap for the unwary.

@entity1 @entity16 @entity66 @entity548
BACKGROUND AND PURPOSE: Single-shot, fast spin-echo, fluid attenuated inversion recovery (SS-FSE-FLAIR) images are frequently used to detect disease in the brain and subarachnoid space in confused or uncooperative @entity1 who may move during the examination. In some of these @entity1 , high signal intensity areas are seen on good-quality images in the subarachnoid space and ventricular system in locations not associated with high CSF flow. These artifacts may simulate @entity548 or @entity66 . The purpose of this article was to determine the cause of these artifacts, describe ways to recognize them, and find methods to reduce or eliminate them. METHODS: Healthy volunteers were studied on 6 occasions with conventional multisection FSE-FLAIR images and SS-FSE-FLAIR images while at rest and while nodding and rotating their heads at different speeds. In addition, SS-FSE-FLAIR images with different section widths of the initial inverting pulse and a non-section-selective initial inversion pulse were performed with the subjects moving their heads in the same way. The scans of 30 successive @entity1 with @entity16 who had been studied with SS-FSE-FLAIR sequences were reviewed for evidence of high signal intensity in the CSF in regions not associated with high CSF flow. RESULTS: Each of the volunteers showed areas of increased signal intensity in CSF at sites apart from those associated with rapid pulsatile CSF flow on SS-FSE-FLAIR images acquired during head motion. The images were otherwise virtually free of motion artifact. The use of a wider initial inversion pulse section and a non-section-selected initial inversion pulse reduced the extent of these artifacts. Nineteen of the 30 @entity1 showed areas of high signal intensity in the CSF in regions not associated with highly pulsatile CSF flow. Six of these @entity1 had negative lumbar punctures for blood and xanthochromia and normal CSF protein levels. CONCLUSION: High signal intensity artifacts may be seen in CSF as a result of head movement on otherwise artifact-free images when imaging uncooperative @entity1 with SS-FSE-FLAIR sequences. These artifacts have a different mechanism and distribution from those caused by CSF pulsation and may simulate subarachnoid and @entity548 . Artifact recognition is aided by signs of @entity1 motion during the examination. The artifacts can be reduced by use of increased section width and non-section-selective initial inversion pulses. Recognition of these artifacts is important, because the circumstances in which the SS-FSE-FLAIR sequence is used and the particular properties of the sequence may conspire to produce a trap for the unwary.
