嗅沟脑膜瘤(Olfactory Meningioma)MRI-CT病例影像诊断分析

来源：ACR Wednesday

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【临床病史】

患者，42岁女性，有头痛史，有头痛史和人格改变，行CT扫描。42-year-old female with history of headache and personality change undergoes a CT brain scan.

【影像图片】

MRI图像

【影像表现】

Axial non contrast enhanced CT [Figure 1] shows a large lesion isointense to the brain in the frontal lobes crossing the midline.
Contrast enhanced axial image Figure 2] shows avid contrast enhancement of the lesion.

T2W axial image (Figure 3) shows a mixed signal large lesion with little surrounding edema.
Proton density axial image Figure 4) shows a lesion which is largely isointense to the surrounding brain parenchyma.
The lesion (Figure 5 and Figure 6) is low signal on TIW image with marked contrast enhancement.
Post contrast TIW sagittal image (Figure 7) shows the lesion to be extra axial with contrast enhancement

【影像诊断】

Olfactory Meningioma 嗅沟脑膜瘤

【诊断要点】

The olfactory groove meningioma accounts for about 10% of intracranial meningiomas.嗅沟脑膜瘤占所有脑膜瘤的10％；They may present with anosmia, personality change, psychological effects, epilepsy and other frontal lobe symptoms.可以表现为嗅觉丧失，性格改变，心理异常、癫痫，以及其他的额叶症状；They are slow growing tumors often reaching large size before detection.病变生长缓慢，常常在发现时已经很大。

【讨论】

Meningiomas are the most common extraaxial tumor. The features which suggest an extraaxial etiology are tumor relationship to the dura, local bony hyperostosis, corticomedullary buckling, displacement of the cortex away form the bone, preservation of the grey/white matter junction and widening of the cisterns. Meningiomas are located in a supratentorial location in about 90% of cases, most commonly at the convexity of the hemispheres. Meningiomas are more common in females.

脑膜瘤是最常见的轴外肿瘤，提示轴外病变的特点是肿瘤与硬膜的相关性，局部的骨肥厚、皮质延髓受压，皮质塌陷、灰白质界面存在，以及脑池的增宽。大约90％的脑膜瘤是位于幕上，最常见于大脑凸面。脑膜瘤更常见于女性。

On unenhanced CT, meningiomas are mostly hyperdense with intense homogenous uniform enhancement. They may be associated with hyperostosis of the adjacent bone. In most cases the surrounding edema is minimal, another feature which distinguishes it from an intraaxial lesion. The dural tail sign is a non-specific sign but one that suggests a meningioma. On MR, meningiomas are isointense to hypointense on TIW images with marked contrast enhancement. On T2W images they are isointense to slightly hyperintense in signal.

平扫ＣＴ，脑膜瘤常常呈高密度，伴有明显的均匀强化。邻近颅骨的肥厚，大多数病例中，周边水肿是轻微的，这同时是鉴别脑内外肿瘤的另一个特征。脑膜尾征是一种非特异性的征像，但是也提示脑膜瘤的可能。在ＭＲ上，Ｔ１序列脑膜瘤是等到低信号，伴有明显的强化。在Ｔ２序列上呈等稍高信号。

The multiplanar imaging capability of MR is useful in defining the exact anatomical location of the lesion.

ＭＲ的多维成像能力有利于精确的显示病变的位置。

The olfactory groove meningioma accounts for about 10% of intracranial meningiomas. They arise in the midline between the crista galli and tuberculum sella. Olfactory groove meningiomas may be symmetrical around the midline or extend to one side or the other. 10 to 15% grow into the ethmoid sinuses. They may present with anosmia, personality change, psychological effects, epilepsy and other frontal lobe symptoms. When large they may involve the visual pathways causing visual field defects. They are slow growing tumors frequently reaching large size before detection.

嗅沟脑膜瘤占所有颅内脑膜瘤的10％。起源于鞍结节与鸡冠间的中线。嗅沟脑膜瘤可以是对称的环绕中线或向一侧或另一侧生长。10％-15％可以向筛窦内生长。临床上可以出现嗅觉丧失、，性格改变，心理异常、癫痫，以及其他的额叶症状。当病变增大，他们可以累及视觉通路导致视野缺损，病变生长缓慢，在发现时常常已经很大。

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