Ecchordosis Physaliphora: Evaluation with Precontrast and Contrast-Enhanced Fast Imaging Employing Steady-State Acquisition MR Imaging Based on Proposed New Classification.

Abstract

Ecchordosis physaliphora (EP) is a notochordal remnant typically located at the dorsal surface of the clivus, which has to be distinguished from the other retroclival lesions. Our aim is to investigate the imaging features of intracranial EP using precontrast and contrast-enhanced fast imaging employing steady-state acquisition (FIESTA). We retrospectively evaluated the precontrast and contrast-enhanced FIESTA images of 399 patients with temporal magnetic resonance imaging to detect "classical EP" and "possible EP." The classical EP was classified into type A (hyperintense excrescence (cyst-like component) on the dorsal surface of the clivus) and type B (hyperintense excrescence plus a hyperintense lesion within the clivus). Possible EP was subdivided as incomplete EP (T2-hypointense protrusion of the clivus) and EP variant (hyperintense lesion within the clivus alone). We found 31 (31 of 399, 7.7%) EPs of which 11 were defined as classical EP (2.7%) and 20 were defined as possible EP (5.0%). Of the 11 classical EPs, 7 (63.6%) were diagnosed as type A and 4 (% 36.4) were diagnosed as type B. Of the 20 possible EPs, 19 were classified as incomplete EP (95.0%) and one was classified as EP variant (5.0%). Contrast-enhanced FIESTA images are helpful in the assessment of EP, although we do not define a role in the current classification proposed by Chihara et al. (Eur Radiol 23:2854-2860, 2013).