Radiographics : a review publication of the Radiological Society of North America, Inc
-
Techniques of Doppler ultrasonography (US) have been available to clinicians for nearly 40 years. The Doppler effect as developed by sound propagation in human tissues and with the velocities observed for the human vasculature produces shifts in the frequencies of returning echo signals. These signals can be processed in a manner that allows the observer to determine the condition of the blood flow. ⋯ The algorithms used are complex, but increasingly powerful microelectronics have made these methods a reality at a reasonable cost. Users of Doppler US techniques must be aware of the complicated aspects of flow in the body, especially with regard to detection of disease in the human vasculature. The continuing development of US equipment aims to provide a greater understanding of hemodynamics and the relationship between blood flow and various disease processes.
-
Emergency radiologic evaluation of the pediatric cervical spine can be challenging because of the confusing appearance of synchondroses, normal anatomic variants, and injuries that are unique to children. Cervical spine injuries in children are usually seen in the upper cervical region owing to the unique biomechanics and anatomy of the pediatric cervical spine. ⋯ Familiarity with anatomic variants is also important for correct image interpretation. These variants include pseudosubluxation, absence of cervical lordosis, wedging of the C3 vertebra, widening of the predental space, prevertebral soft-tissue widening, intervertebral widening, and "pseudo-Jefferson fracture." In addition, familiarity with mechanisms of injury and appropriate imaging modalities will aid in the correct interpretation of radiologic images of the pediatric cervical spine.
-
Review
Imaging of foot and ankle nerve entrapment syndromes: from well-demonstrated to unfamiliar sites.
Nerve entrapment at the foot and ankle involves thin and complex anatomic structures and is underdiagnosed because clinical symptoms and electrophysiologic findings may not contribute to the diagnosis. Nerve entrapment can be secondary to acute trauma or repetitive microtrauma. The latter often results from intensive sports-related activity, inappropriate footwear, or internal foot derangement. ⋯ High-resolution magnetic resonance imaging provides accurate delineation of the nervous system anatomy. Furthermore, technologic developments in the field of radiology are making it possible to obtain clearer, more accurate images. Radiologists must be aware of the main nerve entrapment syndromes at the foot and ankle and be able to perform accurate nerve examinations with different imaging modalities in patients with foot and ankle pain.
-
Foreign bodies are uncommon, but they are important and interesting. Foreign bodies may be ingested, inserted into a body cavity, or deposited into the body by a traumatic or iatrogenic injury. Most ingested foreign bodies pass through the gastrointestinal tract without a problem. ⋯ Metallic objects, except aluminum, are opaque, and most animal bones and all glass foreign bodies are opaque on radiographs. Most plastic and wooden foreign bodies (cactus thorns, splinters) and most fish bones are not opaque on radiographs. All patients should be thoroughly screened for foreign bodies before undergoing a magnetic resonance imaging study.