MR of the temporal bone.

MR imaging continues to make remarkable advances, often beyond our wildest dreams. As these advances occur, I am reminded continually of the importance of technology in determining how we practice medical imaging. It is obvious that most of the pertinent anatomy and diseases of the nervous system as well of those of the head and neck region primarily involve soft tissues. Only rarely do neurologic diseases emanate from bone; the major exception is diseases of the vertebral column that impinge on the spinal cord and nerve roots . Although some bony lesions occur in the head and neck, most diseases in this area arise in soft tissue, with the most common bony involvement being extension to bone of primary soft-tissue malignancies. Despite this overwhelming importance of the soft tissues , most of the history of imaging the nervous system and the head and neck is dominated by bone imaging. This has been determined by technology, not by biomedical need. The earliest "modern" imaging technique-X-rays-provides detailed information about bone and calcified tissues but reveals little about soft tissues. Even advances in X-ray technique, such as pluridirectional tomography, allowed us to see only bone and calcium better. Because the soft tissues of primary interest could not be imaged directly by using conventional X-ray techniques, a variety of manipulations of soft-tissue contrast were devised. Pneumoencephalography, angiography, and soft-tissue pneumography were efforts to change the radiodensity of the soft tissues or to insinuate air between soft-tissue structures and thereby outline their interfaces. Despite extensive time, effort, and radiologic sophistication , imaging of the nervous system and the head and neck was quite primitive until the 1970s. 17