What is your differential?
An astrocytoma is the more likely diagnosis, as the mass is eccentric and slightly expansile. Other tumours to be considered include ganglioglioma, PNET, metastases, although in all cases absence of enhancement is unusual. Non-neoplastic lesions to be considered are demyelination / transverse myelitis - in the setting of an exam, the fact that someone thought it was likely enough to be a tumour to undergo the risk of biopsy is helpful :)
The upper cervical cord is expanded (opposite C1 and C2) by an eccentric mass which is high on T2 and iso-intense to cord on T1 weighted images. The region demonstrates no convincing contrast enhancement and no evidence of haemorrhage. There is evidence of previous surgery in the area.