Magnetic resonance imaging (MRI), nuclear magnetic resonance imaging (NMRI), or magnetic resonance tomography (MRT) is a medical imaging technique used in radiology to investigate the anatomy and physiology of the body in both health and disease. MRI scanners use magnetic fields and radio waves to form images of the body. The technique is widely used in hospitals for medical diagnosis, staging of disease and for follow-up without exposure to ionizing radiation.

MRI has a wide range of applications in medical diagnosis and over 25,000 scanners are estimated to be in use worldwide.[1] MRI has an impact on diagnosis and treatment in many specialties although the effect on improved health outcomes is uncertain.[2] Since MRI does not use any ionizing radiation, its use is generally favored in preference to CT when either modality could yield the same information.[3] (In certain cases MRI is not preferred as it can be more expensive, time-consuming, and claustrophobia-exacerbating).

MRI is in general a safe technique but the number of incidents causing patient harm has risen.[4] Contraindications to MRI include most cochlear implants and cardiac pacemakers, shrapnel and metallic foreign bodies in the orbits. The safety of MRI during the first trimester of pregnancy is uncertain, but it may be preferable to alternative options.[5] The sustained increase in demand for MRI within the healthcare industry has led to concerns about cost effectiveness and overdiagnosis.


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