Inclusion Criteria:  Consent to imaging study Presence of at least 1 lumbar vertebral body bone metastasis > 1 cm in shortest diameter and smaller than 75% of the vertebral body cross sectional area. Metastasis may be determined by pathology, or imaging appearance Eligibility to receive SSRS (determined by treating radiation oncologists) Plan for single-fraction SSRS Standard-of-care spine MRI within 8 weeks of radiation therapy  Exclusion Criteria:  Absolute or relative contra-indication to MRI, including presence of a pacemaker that requires involvement of cardiology/anesthesiology during the scan Prior directed radiation to the involved segment Contra-indication to gadolinium based contrast agents (e.g., allergy, pregnancy) Hardware at the treatment level or hardware affecting visualization of the involved level on MRI