between soft tissues, the injection of contrast media is often necessary. In MRI, however, there are a number of tissue specific parameters which can affect magnetic resonance (MR) signals. One of the most important advantages of MRI is its capacity for displaying soft tissue contrast. An example of this capacity is the discrimination between the gray and white matter of the brain that can be accomplished with MRI. Image contrast can be tailored to the specific clinical application so that specific types of pathology are emphasized. In addition, since MRI is unobstructed by bone, it is especially beneficial in imaging of the brain and spinal cord. MRI also has the unique ability to acquire images in numerous planes without repositioning the patient. Three-dimensional recreations of anatomic structure can be obtained. These characteristics render MRI a very effective and important tool for soft tissue imaging.
             Products meeting the definition of a device under the Federal Food, Drug and Cosmetic Act (FD&C Act or "the Act") are regulated by the Food and Drug Administration (FDA). Medical devices are subject to general controls and other controls in the FD&C Act. General controls of the FD&C Act are the baseline requirements that apply to all medical device manufacturers. Unless specifically exempted, medical devices must be properly labeled and packaged, be cleared for marketing by the FDA, meet their labeling claims, and be manufactured under Good Manufacturing Practices (GMP), which is a mandated quality assurance system.
             FDA regulates devices to assure their safety and effectiveness. To fulfill provisions of the FD&C Act, FDA develops rules to regulate devices intended for human use. These rules regulate various aspects of the design, clinical evaluation, manufacturing, packaging, labeling, commercial distribution, and postmarket surveillance of devices. These regulations are published in the Federal Register. Final regulations ar...