What are the common types of intradural extramedullary spinal lesions, and how can they be differentiated radiologically?

Intradural extramedullary lesions include meningioma, schwannoma/neurinoma, neurofibroma, hemangiopericytoma, lipoma/(epi)dermoid, arachnoid cyst/adhesion, drop/leptomeningeal metastasis, and veins (extramedullary AVM). Meningiomas often present as well-circumscribed, dural-based masses with possible calcifications and dural tail sign on MRI. Schwannomas and neurofibromas are typically iso- to hypointense on T1-weighted images and hyperintense on T2-weighted images, often with a 'target sign' on T2. Key pitfalls include confusing arachnoid cysts with CSF flow artifacts and misidentifying leptomeningeal metastases as inflammatory processes. Differentiation is crucial for appropriate management and prognosis.