What differential would you entertain?
As an intramedullary location is thought most likely, an ependymoma is favoured, although low signal of the enhancing component is unusual, and may relate to previous biopsy. The differential diagnosis includes astrocytoma, hemangioblastoma and/or metastasis (including melanoma). Solitary fibrous tumours of the cord are low signal on T2 and enhance, and thus although rare, should be considered.
How could you assess the low signal component further, specifically trying to determine whether or not it represented blood product?
A susceptibility / T2* sequence would be useful (e.g. Gradient Echo T2). This would demonstrate blooming if the low signal was related to blood products or calcification.
In this case, no blooming would be seen on gradient echo T2* sequences, and as such low signal is unlikely to be due to blood or calcium. What other general type of tissue is low on T1 and T2 sequences?
Fibrous tissue is low on both T1 and T2, on account of poor water content, but may nonetheless enhance. A fibrous tumour would in this instance be though more likely.
Previous T1 to T4 laminectomy. A mass lesion measuring approximately 2 2 x 0.7 x 0.5 centimetres lies at the posterior and right side of the cord at the T2/T3 level. It is associated with expansion of the cord and extensive oedema that extends from the C7 level down to the inferior limits of the scan.
The sagittal images suggests an intra-medullary location. The axial images suggest an exophytic component posteriorly. The mass is iso-intense to hypointense to cord on T1 and markedly hypointense on T2 weighted images. The hypointense component is associated with a marked contrast enhancement. No other areas of abnormal contrast enhancement are seen.