Horizontal-bore MRI
Magnetic resonance imaging is a neuroimaging technique that allows for visualization of both the structure and function of parts of the body, such as the brain. It relies on static magnetic fields--with strengths measured in teslas, or T--and radio-frequency pulses to generate images. MRI has particularly good soft-tissue contrast, allowing it to generate quality images of the brain, musculoskeletal system and cardiovascular system via a number of machine types.
Clinical Scanners
Clinical MRIs typically range from 1.5T to 3T in field strength. They are usually horizontal-bore magnets, and the subject is imaged while lying on his back. The machines are equipped with coils designed to image the head, the torso and extremities such as knees. The controlling software is often generated by the manufacturers, and they provide a variety of image analysis packages. Siemens, General Electric, Philips and Toshiba are among the leaders in clinical MRI manufacturing.
Research Scanners
Research scanners typically range in field strength from 3T to 11.7T. When they're designed for human subject research, they are quite similar to clinical scanners but provide a greater range of hardware and software versatility. Furthermore, agreements can be established with the manufacturers to provide for greater customization than typically allowed with clinical scanners. Higher-field magnets are often used for research with laboratory animals. Siemens, General Electric, Varian and Bruker are among the leading manufacturers of research scanners.
Vertical-Bore Scanners
Vertical-bore scanners are typically used with laboratory animals. They often have field strengths ranging from 4.7T to 7T. Unlike other scanners, the bore of the magnet is vertical, meaning the subject sits upright in the scanner rather than lying on its stomach or back. A Bruker BioSpec 47/40V is an example of a vertical-bore MRI.
Small-Bore Scanners
Small-bore scanners are MRIs with bores that are approximately 20cm in diameter. These scanners are too small for use in human subjects, and are commonly used in small laboratory animals such as rats and mice. The small bore allows for stronger field strengths (typically ranging from 4.7T to 11.7T). It is easier and more cost effective to generate homogeneous static magnetic fields at high field strengths when a small field of view is used. This allows these scanners to produce high-resolution images with excellent contrast. Similar to the makers of other research scanners, the manufacturers of small-bore MRIs allow for extensive control and customization by the users. Siemens, Varian and Bruker are among the leaders in manufacturing small-bore MRIs.
Tags: field strengths, laboratory animals, among leaders, Bruker among, clinical scanners, field strength
