On MRI with gadolinium, glioblastoma most often appears as which pattern?

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Gadolinium-enhanced MRI shows where the blood-brain barrier is disrupted and how a tumor vasculature behaves. Glioblastoma is a fast-growing, high-grade astrocytoma that outgrows its blood supply, producing central necrosis. The viable tumor at the rim has leaky, abnormal vessels, so it enhances irregularly and heterogeneously after gadolinium. This creates a mass that is not uniform, with enhancement around a non-enhancing necrotic center and surrounding edema from vasogenic leakage.

That pattern—an irregular, heterogeneous mass with peripheral enhancement and a central necrotic core—is the classic appearance for glioblastoma on gadolinium MRI. In contrast, uniform edema without a mass, a small cystic lesion without enhancement, or diffuse brain atrophy do not reflect the focal, aggressively enhancing tumor characteristic of GBM.