when preparing to undergo an MRI scan, why are patients advised to remove eyeglasses, watches, jewelry, and other metal objects?

The magnetic fields produced in an MRI scan are huge and alternating. Because the field is changing and large, it will induce a large voltage and eddy current in any conductor that can melt or damage it.

Patients are advised to remove eyeglasses, watches, jewelry, and other metal objects when preparing for an MRI scan due to the following reasons:

1. Magnetic Interference: MRI machines use strong magnetic fields, which can cause metal objects to move or be pulled towards the machine. This can be dangerous if the object is near the patient's body or if it gets caught in the machine's powerful magnet.

2. Imaging Distortion: Metal objects can cause distortion in the MRI images. Since the MRI relies on precise imaging techniques, any metal present in or around the patient can interfere with the clarity and accuracy of the images.

3. Safety Hazards: Certain metals can become hazardous when exposed to the strong magnetic fields of an MRI machine. For example, ferromagnetic materials such as iron, nickel, and cobalt can become projectiles and cause injury to the patient or staff if they are inadvertently introduced into the MRI room.

To ensure a safe and accurate MRI examination, it is important for patients to follow the guidelines provided by the healthcare facility. This typically involves removing all metal objects from the body, including eyeglasses, watches, jewelry, hairpins, bras with metal underwires, belts with metal buckles, and even credit cards with magnetic strips. Patients may also be asked to change into a hospital gown to avoid any potential metal interference.