The most widely accepted and propagated theory of neurotrophic joint pathogenesis is the neurotraumatic one. Seldom published and little known is the neurovascular theory. To gain better understanding of the pathogenesis, we reviewed radiographs of 91 neurotrophic joints with attention to the particular joint affected, the type of changes present (resorptive vs. productive), and the time sequence involved. The pathological findings, when available, were also reviewed. While many joint changes could not be explained on a traumatic basis alone, all could be explained by a vascular mechanism.

Bone density measurement by quantitative computed tomography (QCT) commonly uses an external reference phantom to decrease scan-to-scan and scanner-to-scanner variability. However, the peripheral location of these phantoms and other phantom variables is also responsible for a measurable degradation in accuracy and precision. Due to non-uniform artifacts such as beam hardening, scatter, and volume averaging, the ideal reference phantom should be as close to the target tissue as possible. This investigation developed and tested a computer program that uses paraspinal muscle and fat tissue as internal reference standards in an effort to eliminate the need for an external phantom. Because of their proximity, these internal reference tissues can be assumed to reflect more accurately the local changes in the x-ray spectra and scatter distribution at the target tissue. A user interactive computerized histogram plotting technique enabled the derivation of reproducible CT numbers for muscle, fat, and trabecular bone. Preliminary results indicate that the use of internal reference tissues with the histogram technique may improve reproducibility of scan-to-scan measurements as well as inter-scanner precision. Reproducibility studies on 165 images with intentional region-of-interest (ROI) mispositioning of 1.5, 2.5, or 3.5 mm yielded a precision of better than 1% for normals and 1% to 2% for osteoporotic patients--a twofold improvement over the precision from similar tests using the standard technique with an external reference phantom. Such improvements in precision are essential for QCT to be clinically useful as a noninvasive modality for measurement of the very small annual changes in bone mineral density.

The authors describe a new teaching method for first-year medical students, involving preparation and use of cadaver radiographs in the gross anatomy laboratory. A standard series of radiographs of each cadaver was obtained prior to dissection and provided to each group of students. This technique offers a unique opportunity for radiographic/anatomical/pathological correlation, facilitates an understanding of complex anatomical relationships, and illustrates the application of anatomical knowledge to clinical practice. It can also generate intense student enthusiasm and improve student-faculty communication and teaching relationships.

The study was performed to evaluate detection of soft-tissue foreign bodies using conventional radiography (film-screen radiography), computed radiography printed on films (computed radiography-hard copy), and computed radiography displayed on a computer workstation (computed radiography-soft copy). SUBJECTS AND METHODS. Fifteen foreign bodies of different size, shape, and composition were implanted at different locations in a fresh cadaveric hand, and images were obtained using three radiographic techniques. Images were evaluated by four boardcertified radiologists to ascertain the conspicuity of the foreign bodies with the different techniques. A subjective grade was assigned to each image in an attempt to identify the relative conspicuity of foreign bodies when imaged with the three techniques. RESULTS. Computed radiography-soft copy is the preferred imaging technique for the detection of wood and plastic foreign bodies in soft tissue regardless of the size of the wood or the plastic. No significant differences in conspicuity among the three techniques were demonstrated with glass foreign bodies. CONCLUSION. Detection of soft-tissue foreign bodies is best done using computed radiography-soft copy instead of film-screen radiography and computed radiography-hard copy imaging.