Final answer:
MRI contraindications include the presence of metal implants in the patient and claustrophobia, although open-MRI designs alleviate some of these issues. High costs and noise discomfort are additional concerns.
Step-by-step explanation:
An MRI is contraindicated primarily when a patient has metal implants such as internal sutures, or some prosthetic devices because the powerful magnetic fields used during the scan could dislodge these metal pieces. Additionally, due to the enclosed nature of traditional MRI machines, patients experiencing claustrophobia may find the procedure intolerable. Open-MRI scanners have been developed to address this issue, providing a more comfortable experience for claustrophobic or obese patients.
However, cost considerations and the potential for the noisy environment to cause discomfort are also factors that may limit the suitability of MRI for some patients. Importantly, while MRIs do not expose patients to ionizing radiation, they are not preferred for imaging certain tissues, such as bones, where X-rays or CT scans may be more effective.