Comparison of CT and MR of the head and neck

When comparing computed tomography and magnetic resonance (MR) as imaging modalities in the head and neck region, certain considerations must be kept in mind. First of all, the two technologies are at very different stages in their development. CT scanning has been in clinical use for more than 10 years. It has evolved through a series of product generations and engineering advances into a stable, essentially industry-standard imaging device found in virtually every major medical center. MR, on the other hand, has been in limited clinical use only a fraction of that time. It is undergoing an exponential phase of its development, with different manufacturers employing sometimes radically different techniques to create the MR images. The second consideration is the point of view held by certain proponents of MR. These groups maintain that the real strength of MR does not lie in producing images that compare favorably with the spatial and contrast resolution of CT scanning images but rather rests in the full utilization of the capability of MR to obtain biochemical and physiological data. This may involve the use of coils tuned to atoms other than to protons, such as phosphorus, sodium, and fluorine, and the use of images and spectroscopy based on chemical shift data. They would perhaps argue that a comparison of CT with proton MR imaging overlooks the greatest potential of MR in its ability to detect chemistry in vivo. Because much of the nonproton imaging and chemical shift work with MR is speculative or at best experimental at this time, the remainder of this chapter considers only proton imaging, which is by far the most common type of MR imaging work done today