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This report analyzes the most frequently observed migration paths of disk fragments in 47 patients who had extruded or sequestered disks. Observations are based principally on magnetic resonance (MR) images. When disk fragments moved in a superior (42%) or inferior (40%) direction from the donor disk, the displaced disk components were most frequently (94%) dislodged into the right or left half of the anterior epidural space (AES) and rarely straddled the midline. To explain this phenomenon, the authors investigated the anatomy of the AES by dissecting four cadaver specimens and reviewing 300 MR images of the spine. They conclude that the migrating path of a disk fragment is determined by the anatomy of the AES, a fairly well-defined space delimited posteriorly by the posterior longitudinal ligament and by membranes laterally attached to it. It consists of two compartments separated by a sagitally aligned septum. During migration, sequestered disk fragments usually stay in these compartments.

Fifty-seven subjects underwent proton magnetic resonance (MR) spectroscopy of the second lumbar vertebra to evaluate single-voxel and multivoxel techniques. Measurements included lipid-to-water ratios, lipid fractions, and line width. These data provide information about vertebral fat content. There was an age-dependent linear increase in fat content and sex dependence. A higher fat concentration was found in men. The observed spectra provide a basis for future study to determine clinical utility of vertebral proton MR spectroscopy.

An inverse relationship between bone marrow fat and BMD could not be confirmed. Bone marrow fat can be used to diagnose reduced bone strength nearly as well as BMD. The bone marrow fat/BMD ratio is a significant diagnostic indicator of bone weakening.

The techniques used in this study demonstrated that brain activation to olfactory stimuli could be measured quantitatively such that differences between groups of subjects (in this case men and women) could be compared. Although localization of brain activation was not the major thrust of this study, activation to olfactory stimuli was found not only in brain regions previously associated with processing of olfactory information but also in several other areas of frontal cortex, in cingulate gyrus, and in several components of the limbic system. This is the first study in which activation in human brain parenchyma of normal humans to olfactory stimuli has been quantitated by fMRI.

These studies indicate that (a) odors can be imagined and similar brain regions are activated by both imagined and corresponding actual odors; (b) imagination of odors elicits quantitatively less brain activation than do actual smells of corresponding odors in normal subjects; (c) absolute brain activation in men by odor imagination is greater than in women for some odors, but on a relative basis, the ratio for odor imagination to actual smell in women is twice that in men; (d) odor imagination, once the odor has been experienced, is present, recallable, and capable of inducing a relatively constant degree of brain activation even in the absence of the ability to recognize an actual corresponding odor.

This study reports the sonographic and computed tomography (CT) findings in seven infants and neonates with intracranial calcifications and a spectrum of underlying disorders, including toxoplasmosis, cytomegalic inclusion disease, transverse/straight sinus thrombosis, and probable anoxia. Neurotropic infectious disease usually produced clumped or subependymal calcifications accompanied by sometimes bizarre ventricular configurations and prominent periventricular cystic encephalomalacia. Sonography failed to identify prospectively intracranial calcifications in two of the three patients without infection, although calcifications were visible in retrospect. Overall, CT provided optimum visualization of intracranial calcifications.

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