Neuroradiology brain tumor board review. This lecture is geared towards the ABR core exam for residents, but it would be useful for review for the ABR certifying exam or certificate of added qualification (CAQ) exam for neuroradiology.

This case shows an MRI of the brain with a pretty well-defined, expansile mass in the inferior aspects of the right parietal lobe with some extension into the adjacent frontal and temporal lobes. It is markedly T2 hyperintense, but somewhat less intense centrally on FLAIR. On pre- and post-contrast imaging, this shows that the tumor is predominantly non-enhancing, although there is a thin rim of enhancement around the anterior margin.

1:15 The diagnosis is: anaplastic astrocytoma (grade 3)

Anaplastic astrocytomas are grade 3 astrocytomas that are most commonly IDH mutated. They tend to have slightly more mass effect and enhancement than grade 2 tumors but do not have the necrosis and avid enhancement of grade 4 tumors most of the time. 1p19q codeletion is absent in these tumors because if present these would be oligodendrogliomas.

The T2 mismatch sign is a relatively recently described imaging finding of IDH mutated astrocytomas. When a portion of the tumor is very bright on T2 but suppresses on FLAIR, this is a pretty specific sign for IDH-mutation. This fact could appear on an ABR exam, especially the CAQ exam.

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