Evaluation of Intradural Ecchordosis Physaliphora With Three-Dimensional Fluid-Attenuated Inversion Recovery.

OBJECTIVE: This study evaluated the efficacy of 3-dimensional fluid-attenuated inversion recovery (3D FLAIR) for detecting intradural ecchordosis physaliphora (EP). METHODS: We retrospectively determined the presence or absence of intradural EP on 3D FLAIR for 3888 consecutive patients, classifying the EP as "classical" or "possible" and analyzing the prevalence, size, and presence or absence of an intraosseous stalk. Where available, magnetic resonance cisternography images were compared with the 3D FLAIR images. RESULTS: Intradural EP was identified in 50 patients (1.3%): 36 (0.9%) classical and 14 (0.4%) possible. The classical EPs were significantly larger than the possible EPs (P < 0.01). Nine EPs (18.0%) showed an osseous stalk. Magnetic resonance cisternography was performed for 19 EPs (16 classical, 3 possible), detecting all 16 classical EPs but none of the possible EPs. CONCLUSIONS: Classical EPs were detected by 3D FLAIR as with magnetic resonance cisternography. The 3D FLAIR findings suggested a new type of possible EP variant previously unreported.