Specialized MRI Techniques
Specialized types of MRI machines are used to conduct different types of scans, usually with the purpose of locating specific types of diseases or conditions. Like the basic style of MRI, each uses some for of magnetic field adjustment to aid in creating an image.
One of the most popular examples of a specialized MRI is the diffusion technique. This is used to measure the motion of water molecules from one location to another, known as diffusion. In the most basic sense, the magnetic resonance scan can identity the water molecules within the body. With the knowledge of how water flows through the body in different sections, the rate and location of diffusion is identified.
Magnetization transfer MRI scans also work with the concept of water, but in a different way. Within the body, there are two types of water molecules, free water found in large collections in the body and hydration water, essentially lone water molecules throughout solid tissues. The rotational frequency of free water is faster than hydration, allowing the magnetic fields to identify the different types.
Other types of MRI machines are used to identify specific tissues using a combination of rotation rates and time gradients. An angiography is used to identify narrowing or expanding arteries, also known as stenosis and aneurysms respectively. Intracranial cerebrospinal fluid finds the flow of fluids through ventricles to identify lesions and problems within the circulatory system. Spectroscopy measures the results of cellular processes known as metabolites. Each type of metabolite is identified by a particular adjustment to the magnetic field. The brain is analyzed by a functional MRI scan. A low resolution with a rapid rate of magnetization show the changes in brain activity depending on the blood-oxygen level.
All of the different types of MRI machines have become highly useful to the medical industry. Today, they provide a cost-effective and safe alternative to other invasive forms of diagnostic imaging.
Above left: MRI of Knee. (Supplied by Test21 at Wikimedia Commons; GNU Free Documentation License; http://upload.wikimedia.org/wikipedia/commons/a/a9/MR_Knee.jpg)