You have had a partial tear of the medial and lateral ligaments which is like an ankle sprain. You have not indicated the reasons for the MRI or the time from injury when this scan was done. Usually acute injuries heal uneventful and the cast is really helpful. However if there is persistent instability or pain, I would advise a proper examination, and maybe a repeat scan. If there are no symptoms then it is assumed that healing is complete and nothing needs to be done.
Next Steps
Please visit an Orthopedic surgeon.