Mehnert Florian, Beschorner Rudi, Küker Wilhelm, Hahn Ulrich, Nägele Thomas
Department of Neuroradiology, University of Tuebingen, Hoppe-Seyler-Str 3, D-72076 Tuebingen, Germany.
AJNR Am J Neuroradiol. 2004 Nov-Dec;25(10):1851-5.
Ecchordosis physaliphora (EP), found in about 2% of autopsies, is a clinically inconspicuous notochordal remnant appearing at the dorsal wall of the clivus. To our knowledge, a systematic review of its MR features does not exist. The aim of this study was to describe the MR imaging findings of incidentally found retroclival EP with special respect to its differentiation from intradural chordomas.
We reviewed 300 consecutive 1.5-T MR imaging studies that included thin-section transverse T2-weighted images of the skull base for the presence of a retroclival EP. In cases in which an EP was identified, two neuroradiologists observed MR signal intensity characteristics, contrast enhancement, size, form, stalk of EP, and signal intensity changes of the adjacent clivus.
Five cases with retroclival EP were found (incidence, 1.7%). In all cases, the ecchordoses was hyperintense on T2-weighted images and hypointense on T1-weighted images. Contrary to the reported findings in chordomas, none of the lesions showed contrast enhancement. In four cases, there were signal intensity changes in the adjacent clivus. A stalklike connection between clivus and EP was seen in three patients.
Because of the benign character of EP and the difficulties in its histopathologic differentiation from chordomas, precise knowledge of the radiologic characteristics of EP is important. On the basis of these five cases and a review of literature, contrast enhancement and the presence of clinical symptoms seem to be highly reliable parameters in the differential diagnosis of intradural chordoma and EP.
黏液囊肿样脊索瘤（EP）在约2%的尸检中被发现，是一种临床症状不明显的脊索残留，出现在斜坡后壁。据我们所知，目前尚无对其磁共振成像（MR）特征的系统综述。本研究的目的是描述偶然发现的斜坡后EP的MR成像表现，尤其关注其与硬膜内脊索瘤的鉴别诊断。
我们回顾了300例连续的1.5-T MR成像研究，这些研究包括颅底的薄层横轴位T2加权像，以寻找斜坡后EP。在发现EP的病例中，两名神经放射科医生观察了MR信号强度特征、对比增强、大小、形态、EP的蒂以及相邻斜坡的信号强度变化。
发现5例斜坡后EP（发生率为1.7%）。所有病例中，脊索瘤在T2加权像上呈高信号，在T1加权像上呈低信号。与脊索瘤的报道结果相反，所有病变均未显示对比增强。4例相邻斜坡有信号强度变化。3例患者可见斜坡与EP之间有蒂样连接。
由于EP的良性特征及其在组织病理学上与脊索瘤鉴别困难，准确了解EP的影像学特征很重要。基于这5例病例及文献复习，对比增强和临床症状的有无似乎是硬膜内脊索瘤与EP鉴别诊断中高度可靠的参数。
