Biomedical subjects
Publications and source records attributed to R T Bergeron.
The authors describe a simple myelographic technique for cervical spinal cord injuries, involving lateral puncture at C1--C2 and injection of metrizamide with the patient supine. This technique is reliable and offers advantages over Pantopaque and/or gas myelography.
Computerized tomography has manifest usefulness in the roentgenologic identification of intracranial masses, and acoustic neuromas are no exception. Nonetheless, traditional roentgenographic examinations for the workup of acoustic neuromas should not yet be completely discarded in favor of this new modality. Computerized tomography scanning is an insensitive and unreliable technique for delineating the size and configuration of the internal acoustic canals. With current technology, it will not reliably show neuromas less than 1.5 cm in cross-sectional dimension. Technical artifacts may also contribute to false-negative and though rare to false-positive findings. The false-negative rate will be unacceptably high in the presence of small lesions if this technique is treated as a definitive examination rather than a screening one. Though uncommon, it may also be negative in the presence of relatively large lesions.
Multiple star test objects were placed so as to record the entire field covered on a 35 X 43-cm (14 X 17-in.) film and radiographed to determine the apparent shape of the focal spot and the directions in which degradation is maximum and minimum. It was found that geometric unsharpness decreases along lines radiating outward from the center of the anode shadow. The small focal spots used in magnification may be anticipated to behave in a similar fashion. It was also shown experimentally that truly lateral resolution is approximately constant over the field. A theoretical explanation for this finding is offered.
Air-fluid levels in the sphenoid sinus have been described in association with skull fracture, cerebrospinal fluid rhinorrhea, and sinusitis. The authors have observed this sign in the absence of significant trauma in patients with epistaxis and nasal packing. The fluid is probably normal sinus secretion retained due to prolonged recumbency, although other explanations for its accumulation are discussed.
X-ray tubes having similar resolution capabilities along the central ray were compared for their wide-field characteristics. It has been suggested that focal spot size, and therefore resolution capability, along the cathode-anode axis may vary in a manner which is dependent upon the tube target angle. The authors show that differences beyond the effects of target angle occur, the extent of those differences varying from tube to tube. Although 2 different-sized focal spots may be adjusted to have equivalent central beam resolution capabilities, they can exhibit different imaging capabilities at wide-angle (off central axis) position. More than one parameter (equivalent focal spot size) is needed to characterize the behavior of a focal spot.
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