On axial T2 and coronal STIR, there is a partially imaged right-sided hyperintense retrofascial mass, encompassing and abutting the psoas major muscle. The mass appears to extend further inferiorly into the iliopsoas compartment and involves the quadratus lumborum muscle.
Well-defined hyperintense areas in the vertebral bodies of T11, L3 and S1 on sagittal T1 and T2, likely vertebral hemangiomas.
Normal morphology and enhancement of the spinal cord. Normal thoracolumbar alignment. No appreciable bone marrow edema or infiltrates.
In the context of the noted history of fever and back pain, the most likely differential of this partially imaged mass would be a psoas abscess. Recommend CT abdominal pelvis with contrast for further characterization.