An Investigational Scan (hpMRI) for Monitoring Treatment Response in Patients With Thyroid Cancer and Other Malignancies of the Head and Neck Undergoing Radiation Therapy and/or Systemic Therapy

This study uses a special type of MRI scan — called hyperpolarized MRI — to track how well radiation or drug treatments are working in people with thyroid cancer or other head and neck cancers. This scan can give real-time information about how cancer cells are using energy, helping doctors make better treatment decisions. **You may be eligible if...** - You have been diagnosed with thyroid cancer or another cancer of the head or neck - You are currently planned for radiation therapy and/or systemic drug treatment **You may NOT be eligible if...** - You have severe claustrophobia (fear of enclosed spaces) - You have metal implants or devices (like a pacemaker) that are not MRI-compatible - You have a history of irregular heart rhythms - You are allergic to MRI contrast dye (Gadavist) - Your kidney function is significantly impaired - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.