Magnetic resonance imaging (MRI) is a diagnostic procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. MRI makes better images of organs and soft tissue than other scanning techniques, such as CT or X-ray. MRI is especially useful for imaging the brain, spine, the soft tissue of joints, and the inside of bones.

MRI is a unique imaging method because, unlike the usual radiographs (X-rays), radioisotope studies and even CT scanning, it does not rely on radiation. Instead, radio waves are directed at protons, the nuclei of hydrogen atoms, in a strong magnetic field. The protons are first "excited" and then "relaxed;" these then emit radio signals, which can be computer-processed to form an image. In the body, protons are most abundant in the hydrogen atoms of water—the "H" of H₂O—so that an MRI image shows differences in the water content and distribution in various body tissues. Even different types of tissue within the same organ, such as the gray and white matter of the brain, can easily be distinguished.

Over the years, MRI has become the diagnostic imaging modality of choice in evaluating brain and spine tissue structure because of the excellent definition it provides. The availability of high-definition diagnostic methods, such as MRI, is becoming increasingly important as the population ages and the number of patients with brain, spine and nervous system diseases rises.

The new 3-Tesla MRI system represents the latest advance in clinical MRI technology. It takes magnetic resonance imaging to the next level by allowing doctors to see not only structures within the body, but also the metabolic function of those structures. It is twice as powerful and fast than standard MRI machines. It provides detailed images of structures that cannot be imaged by earlier MRI technology, such as blood vessels as small as 200 to 300 microns. The system localizes areas of activation more precisely, enabling accurate mapping of brain function more than 90% of the time.

The new 3-Tesla MRI system can more accurately diagnose routine and hard-to-detect conditions such as heart vessel problems, stroke, aneurysms, prostate cancer, spinal cord lesions, spinal disc injuries, bone, joint and cartilage damage, and renal artery problems. It provides patients with a faster, quieter and more detailed imaging process, and enhances research within the Institute of Radiology.

St. Luke’s Medical Center is the only hospital in the Philippines equipped with a 3-Tesla MRI. St. Luke's also has a 1.5 Tesla MRI.