Patients enrolled in the parent study will be identified at the 6 month follow-up and recruited in terms of whether they report chest pain. A total of 30 participants will be recruited (15 with and 15 with no pain) to undergo a single MRI session in which functional MRI will be done on the brain stem and spinal cord and anatomical MRI images will be collected for specific chest and neck structures. This will indicate whether there are long-term differences in pain processing and/or physical damage to neck and chest structures in those with and without chronic pain 6 months following coronary artery bypass graft surgery. All functional and anatomical MRI images will be reviewed and interpreted with study personnel blinded to whether the patient is reporting pain or no pain at their 6 month follow-up interview.