每天朗读一段医学影像学英语文章
Background：
Meningiomas are extra-axial tumors arising from arachnoid cells of the meninges, which originate from the neural crest. They account for ~13 to 20% of all primary intracranial tumors and can be found at any location along the arachnoid membrane, most commonly along the cerebral convexity. The peak incidence is at 45 years of age, with a strong female predominance. Malignant lesions are very rare, but metastases may occur by seeding via the cerebrospinal fluid. Extraneural metastases to the lungs, liver, and lymph nodes may also occur. Because most meningiomas are benign and curable tumors, complete surgical resection remains the treatment of choice.
CT：More than 50% of meningiomas are hyperdense on unenhanced CT scans, and calcification can be seen in ~14%. Hypodensity surrounding the tumor is likely related to brain edema. Hyperostosis of the adjacent bone can also be seen on bone window.
Marked homogeneous enhancement with well-defined borders is typically seen on post-contrast CT. Heterogeneous enhancement and tumor necrosis are unusual and suggest a more aggressive lesion.
MRI：Meningiomas are often homogeneously isointense to the brain parenchyma on T1-weighted sequences and hyperintense on T2-weighted sequences. Areas of flow void may be seen on T2 weighted images, which may represent the highly vascular nature of these lesions and/or calcifications. Contrast enhancement is necessary to determine the relationship of a meningioma to adjacent major cerebral arteries and veins.
CTA/MRA：The use of both CTA and dynamic MRA to determine the vascularity of meningiomas before pre-operative embolization has been reported. Enlargement of the feeding arteries, typically from the middle meningeal artery for convexity lesions, can be demonstrated.
Notes:
1. arachnoid /ə'ræknɔɪd/ adj. 蛛网状的,蛛网膜的 n. 蛛网膜
2. convexity /ˌkɑn'vɛksəti/ n. 凸状,凸面
3. cerebrospinal /ˌsɛrəbro'spaɪnl/ adj. 脑脊髓的
4. hyperostosis /ˌhaɪpərɑ'stosɪs/ n. 骨肥大,骨肥厚
5. parenchyma /pə'rɛŋkɪmə/ n. 实质,软组织
来源：每天朗读一段医学影像学英语文章
圈主
深圳市人民医院放射科副主任医师杨敏洁
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