Does the appearance of the lesion on FIESTA and DWI series add something to the interpretation?
Yes, it reflects the high fluid content of the lesion.
A posterior mediastinal / para-vertebral, oval-shaped mass lesion of about 7 X 6 X 5cm size is seen along the D4, D5 D6 and D7 vertebrae. The mass shows low signal on T1WI, high signal on T2WI and FIESTA, and no abnormal diffusion restriction.