少见型脑膜瘤的CT诊断

目的探讨颅内少见型脑膜瘤的CT表现，并提高其诊断准确性。方法15例经手术病理证实的少见型脑膜瘤，包括Nauta型囊性脑膜瘤8例，恶性脑膜瘤4例，多发性脑膜瘤2例以及完全钙化性脑膜瘤1例，术前均经CT平扫，14例又经对比增强扫描。对所有患者的CT表现结合文献复习进行了回顾性分析。结果多数脑膜瘤位于幕上。Nauta型囊性脑膜瘤CT平扫呈囊实性肿块，增强扫描示肿瘤实质部分明显强化，部分囊壁有强化。恶性脑膜瘤CT平扫呈不规则形混杂密度肿块，或囊性肿块伴结节，肿瘤边缘不规则，增强后实质部分明显强化，瘤周水肿广泛。多发性脑膜瘤CT平扫示多发结节灶，增强扫描示肿瘤轻度强化。完全钙化性脑膜瘤CT平扫呈钙化团块，邻近颅骨骨质增生硬化，瘤周无水肿。本组CT术前正确诊断10例，误诊5例。结论颅内少见型脑膜瘤术前CT易误诊。综合分析各型的CT特征，有助于作出正确诊断和鉴别诊断。

CT diagnosis of uncommon meningiomas

Objective To study the CT findings of uncommon meningiomas and to elevate the diagnostic accuracy. Methods Fifteen patients with surgically and pathologically proved uncommon meningomas which comprised Nanta type cystic meningioma （n =8）, malignant meningioma（n =4）, multiple meningioma（n =2）, and fully calcified meningioma（n =1） underwent preenhanced CT scan,14 patients underwent additional postenhanced CT scans. The CT findings of all patients were retrospectively analyzed together with the review of literature. Results The most meningiomas in the group patients located in the supratentorial region. Nauta type meningiomas were cystic-solid masses on preenhaneed CT images and obvious enhancement of solid components, partial enhancement of cystic walls on postenhanced CT images. Malignant meningiomas were irregular masses with heterogeneous density or cystic mass associated with nodules, tumor rim was irregular on preenhanced CT images and obvious enhancement of solid parts and extensive peritumor edema on postenhanced CT images. Multiple meningiomas were multiple nodular loci on preenhancend CT images and slight enhancement of tumors on postenhanced CT images. Fully calcified meningioma seen on preenhanced CT image was a calcified mass associated with bony proliferation and sclerosis of neighbour skull bones but no peritumor edema was found. Among 15 cases in the group, preoperative CT correctly diagnosed 10 cases and misdiag- nosed 5 cases. Conclusion Uncommon meningiomas are easily misdiagnosed by preoperative CT scanning, however, a comprehensive analysis of CT features acquired from varied meningiomas is very helpful to make definite diagnosis and differential diagnosis.