Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging (MRI) is an imaging technology that uses powerful magnets to generate highly detailed pictures of the bodyâs interior structures. MRI is especially useful for imaging soft tissue structures and has excellent applications for the diagnosis and surgical staging of malignant mesothelioma.
MRI scans are produced by an MRI scanner, a technologically-advanced imaging machine that uses magnets to generate a strong magnetic field that excites protons found in our bodies’ water molecules. These protons align with this magnetic field, and are then temporarily pushed out of alignment by a second magnetic field that is created perpendicular to the main field. When these protons drift back into alignment with the main field, they emit a particular radiofrequency signal that is detectable and âimage-able.â A variety of agents can be used to enhance or otherwise augment the standard imaging signal, so the final image can be precisely tailored to provide a detailed picture of the area under investigation.
Like CT, MRI is a high-resolution imaging medium that is vastly superior to x-ray for visualizing internal tissue structures. Images from CT and MRI demonstrate similar spatial resolution, but MRI has greater soft tissue contrast. This means that MRI is better able to visualize small differences between similar tissue structures or differences within the same tissue structure.
CT is usually the first imaging test given to people suspected of mesothelioma because itâs able to identify the diseaseâs typical presentation in most cases. However, MRIâs more precise visualization of the soft tissues means that it will be deployed when a CT is inconclusive or simply unable to make a determination. For example, CT is generally poor at accurately determining the extent of infiltration into the chest wall and the areas surrounding it, so MRI will be used instead.
One of the most important uses of MRI in mesothelioma medicine is for surgical staging and planning. Surgeons use MRI to visualize how extensively the disease has invaded surrounding tissues and will then incorporate this information into their surgical strategy. Even though MRI is not able to fully describe the area of complete infiltration, it can do so much more accurately than can CT.
Another difference between CT and MRI has to do with the long-term risks associated with their use: CT utilizes ionizing radiation, which can cause damage to human tissues, while MRI uses magnetism, which has not been shown to cause any damage. A healthy adult undergoing a CT on a well-maintained machine is unlikely to suffer any ill effects from the procedure, but there are still questions in medical circles as to the long-term health effects associated with receiving numerous x-ray and CT procedures. MRI has none of these associated risks.