内淋巴囊肿瘤的CT和MRI影像学表现分析

CT and MRI features of endolymphatic sac tumor

目的探讨内淋巴囊肿瘤(ELST)的CT和MRI表现。方法回顾性分析2011年6月至2019年5月复旦大学附属眼耳鼻喉科医院19例20耳经病理证实的ELST患者的临床和影像学资料,包括病灶的位置、大小、边界、密度、骨质破坏、MRI平扫及增强的信号特点、DWI及动态增强特点。采用配对t检验比较病灶和同侧翼内肌ADC值的差异。结果19例患者中男6例、女13例,其中1例为双耳发病。CT主要表现为主体位于岩锥后缘、前庭导水管周围的软组织肿块影,边界不清,密度稍高。CT值为(78.6±21.9)HU。19耳病灶骨质呈虫蚀样侵蚀破坏,肿块内大量残存骨质。骨质破坏累及中耳乳突16耳、颈静脉孔11耳、半规管10耳、面神经管7耳、内听道9耳。16耳肿块T_(1)WI、T_(2)WI上均为中央等信号伴周围高信号,4耳T_(1)WI上无明显高信号。T_(1)WI上高信号部分呈周围环绕分布10耳、偏一侧分布5耳、全病灶散在分布1耳。9耳肿块内部出现血管流空影,2耳T_(2)WI图像上见液-液平面。T_(1)WI、T_(2)WI均为等信号部分增强后呈明显强化,其余部分不强化。14耳行DWI,扩散未见明显受限,ADC值[(1.25±0.08)×10^(-3) mm^(2)/s]高于翼内肌(t=4.437,P=0.001)。2耳行动态增强扫描,时间信号强度曲线呈速升缓降趋势。结论ELST的CT和MRI表现具有一定特征性,病灶主体位于岩锥后缘、前庭导水管周围,骨质呈虫蚀样破坏,T_(1)WI上肿块周边部分明显高信号,扩散多不受限,有助于术前精确诊断。

Objective To explore CT and MRI features of the endolymphatic sac tumor(ELST).Methods The CT and MRI morphology confirmed by surgical pathology for 19 patients with ELST were retrospectively analyzed from June 2011 to May 2019 in Eye&ENT Hospital of Fudan University.The features of CT and MRI included location,size,adjacent structures invasion,CT values,bone destruction,features of T_(1)WI and T_(2)WI,enhancement distribution characteristics,dynamic enhancement curve morphology,DWI signal characteristics.The ADC values of the lesions and ipsilateral medial pterygoid muscles were compared using a paired t test.Results Nineteen ELST patients(one with bilateral diseases)were included.Totally 20 ears(right 9 and left 11)of 13 females and 6 males were studied.The masses with slightly high-density and obscure boundary were located around the vestibular aqueduct at the posterior edge of the petrosal bone.Bone destruction involved mastoid process of the middle ear(16 ears),jugular foramen(11 ears),semicircular canal(10 ears),facial nerve canal(7 ears)and internal auditory canal(9 ears).A large amount of residual bone could be found in the interior of nineteen masses.The CT value was(78.6±21.9)HU.The lesion showed central iso-intensity and peripheral hyperintensity on T_(1)WI and T_(2)WI in 16 ears,while no obvious hyperintensity on T_(1)WI in the other 4 ears.The hyperintensity on T_(1)WI was around the margin of the lesion in 10 ears,situated at lateral side in 5 ears and all over the lesion in 1 ear.Flow voids signals could be seen in 9 ears as well.Liquid-liquid plane was seen on T_(2)WI in 2 ears.The solid mass portion which showed iso-intensity on both T_(1)WI and T_(2)WI presented marked enhancement on contrast-enhanced T_(1)WI,while other part of the mass no enhancement.DWI of 14 ears illustrates no evidence of restricted diffusion,and the ADC value[(1.25±0.08)×10^(-3) mm^(2)/s]was slightly higher than that of the medial pterygoid muscles(t=4.437,P=0.001).The style of time-signal intensity curves of the dynamic contrast-enhanced MRI was rapidly ascending followed by descending curves in 2 ears.Conclusion Imaging findings of ELST have some characteristics,including located around the vestibular aqueduct at the posterior edge of the petrosal bone,bone destruction,peripheral hyperintensity on T_(1)WI and no restricted diffusion,which is helpful for its diagnosis.