Is an IV contrast die needed for a brain and cervical spine MRI?

Depends on problem. Much can be learned from MRI without contrast but if a vascular anomaly or tumor is suspected the IV dye helps to show the extent of the lesion and it's location in areas that are not well delineated without the dye. If your doctor recommended it, you should go ahead and have the dye injected. Avoid it if you are allergic to the dye.