Intraventricular CSF pulsation artifact on fast fluid-attenuated inversion-recovery MR images: analysis of 100 consecutive normal studies.

BACKGROUND AND
PURPOSE: CSF pulsation artifact is a pitfall of fast fluid-attenuated inversion-recovery (FLAIR) brain MR imaging. We studied ventricular CSF pulsation artifact (VCSFA) on axial FLAIR images and its relationship to age and ventricular size.
METHODS: Fast FLAIR axial images were obtained on a 1.5-T unit (8000/150/2 [TR/TE/ excitations], inversion time = 2200, field of view = 24 cm, matrix = 189x256, and 5-mm interleaved sections). Two observers rated VCSFA (hyperintensity on FLAIR images) in the lateral, third, and fourth ventricles by using a three-point ordinal scale in 100 consecutive subjects (ages 20-86 years) with normal brain MR studies. Left-to-right third ventricular width was also measured.
RESULTS: Seventy-two subjects had VCSFA in at least one ventricular cavity. The fourth ventricle was the most common site of VCSFA (n = 58), followed by the third ventricle (n = 47) and the lateral ventricles (n = 13). VCSFA was usually severe in the third and fourth ventricles and less severe in the lateral ventricles. Fourth ventricular VCSFA was significantly associated with third ventricular VCSFA. Increasing third ventricular size and, to a lesser extent, increasing age was significantly associated with VCSFA. Ghost pulsation of VCSFA occurred across the brain parenchyma in the phase-encoding direction. VCSFA seen in the fourth ventricle on axial FLAIR images disappeared on sagittal FLAIR images in one subject.
CONCLUSION: VCSFA on axial FLAIR images represents inflow artifact caused by inversion delay and ghosting effects. VCSFA might obscure or mimic intraventricular lesions, especially in the third and fourth ventricles. Although common in adults of all ages, VCSFA is associated with advancing age and increasing ventricular size. Thus, altered CSF flow dynamics that occur with ventriculomegaly and aging contribute to VCSFA on axial FLAIR MR images.