Significance of corrective growth of opposite physes in the surgical correction of deformity following epiphyseal injury around the knee joint

Deformation due to growth disturbance after epiphyseal fractures around the knee may involve more than the primarily injured epiphysis, as spontaneous corrective growth of the opposite epiphyseal plate can take place in an attempt to maintain overall alignment of the leg. As a result, there will be an inclination in the knee joint line if corrective osteotomy is only performed for the primary angulation. We report two cases of this complex deformity in which corrective osteotomies of both the distal femur and the proximal tibia were performed, resulting in correct alignment of the overall leg axis and knee joint axis. Received: 25 May 1996 Accepted: 20 November 1996     

True epiphrenic diverticulum of esophagus secondary to tubercular adenitis.

Ephiphrenic esophageal diverticulum is rare and usually is a pulsion-type pseudodiverticulum that occurs in association with motility disorders of the esophagus. We report a 35-year-old man with tubercular lymphadenitis causing true traction type of epiphrenic diverticulum. Esophageal diverticulectomy and esophagomyotomy was done; he is doing well on antitubercular drugs.     

The Digital Imaging Workstation

Picture archiving and communication systems (PACS) are expected to convert film-based radiology into a computer-based digital environment, with associated cost savings and improved physician communication. The digital workstation will be used by physicians to display these soft-copy images; however, difficult technical challenges must be met for the workstation to compete successfully with the familiar viewbox. Issues relating to image perception and the impact on physicians practice must be carefully considered. The spatial and contrast resolutions required vary according to imaging modality, type of procedure, and class of user. Rule-based software allows simple physician interaction and speeds image display. A consensus appears to be emerging concerning the requirements for the PACS workstation. Standards such as the American College of Radiology/National Electrical Manufacturers Association Digital Imaging and Communication Standard are facilitating commercial applications. Yet much careful study is needed before PACS workstations will be fully integrated into radiology departments. Abbreviations: CRT = cathode ray tube, H&D = Hurter and Drifield, PACS = picture archiving and communication system, ROC = receiver operating characteristic, S/N = signal-to-noise ratio. Partially supported by grant HL-33332 from the National Heart, Lung, and Blood institute, U.S. Public Health Service. Address reprint requests to R.L.A. Copyright © 1990 by the Radiological Society of North America. Radiology 176:303-315, 1990. Reprinted with permission.     

Reliability of soft-copy versus hard-copy interpretation of emergency department radiographs: a prototype study

OBJECTIVE: The purpose of this study was to compare the diagnostic reliability of hard-copy and soft-copy interpretation of radiographs obtained in the emergency department using a methodology for evaluating imaging systems when independent proof of the diagnosis is not available. MATERIALS AND METHODS: We collected radiographs from a stratified sample of 100 patients seen in the emergency department. The images were obtained using computed radiography, and the digital images were printed on film and stored for display on a workstation. A group of seven experienced radiologists reported the cases using both film and the workstation display. The results were analyzed using mixture distribution analysis (MDA). RESULTS: The reliability expressed as the percentage of agreement of a typical observer relative to the majority was computed from the MDA. The result was 90% for both hard copy and soft copy with bootstrap confidence intervals of 86-94%. CONCLUSION: We conclude that, in the emergency department, soft-copy interpretation is as reliable as hard-copy interpretation. The strength of this conclusion depends on the validity of the MDA approach as well as the extent to which the observer sample and case sample are representative of the emergency department.     

Magnetic resonance imaging of fluorine in rats infused with artificial blood

An MRI pulse sequence has been developed that enables the visualization of a perfluorocarbon (PFC) emulsion in the vascular system of rats. Images were made at 0.12T on a clinical imaging system using a small receiver coil, at intervals of approximately 2 hours, two days, two weeks, and two months after replacement of 50% of total blood volume. The most successful technique produced PA projections of the entire torso for both the fluorine and proton components. Direct comparison allowed identification of PFC in heart, lung, liver, spleen, and large vessels both in vivo and postmortem. Potential clinical applications to vascular imaging are discussed.     

Searching for lung nodules. Visual dwell indicates locations of false-positive and false-negative decisions

Eye position recordings made while radiologists searched chest images for lung nodules showed that regions falsely reported positive or suspicious received prolonged visual attention. Correlation of regional fixation dwell time with independent ratings of image features indicated that more than 90% of false-positive decisions were caused by some perturbation in the image that aroused the suspicion of the viewer. The remainder apparently arose from within the viewer. Most missed nodules (false-negative reports) also received prolonged visual attention, implying an active decision not to perceive a nodule. The data are interpreted to show that roughly one task-related decision is made during each second of scanning a radiograph. This departs from the central assumption of the traditional signal-detection model based upon one decision per image.     

Sodium nuclear magnetic resonance imaging of neuroblastoma in the nude mouse

The average concentration of sodium is known to be elevated in some tumors relative to normal tissues, and necrosis is suspected of being a possible cause. We have performed in vivo sodium-23 magnetic resonance imaging (MRI) of IMR-5 neuroblastoma in the athymic nude mouse on a 1.9-Tesla, small-bore animal imaging system. We compared the sodium images with histologic analysis for necrosis and with proton images, chemical measurements of water and blood content, and sodium and potassium concentrations. We found that the sodium concentrations determined by MRI were proportional to the fraction of the tumor tissue that was necrotic. Correlation coefficients varied from 0.65 to 0.78, depending upon how the data were selected. With further refinement it is possible that the sodium concentration measurements determined noninvasively by MRI may have applications as part of clinical diagnosis and staging of soft tissue tumors.     

Computer-displayed eye position as a visual aid to pulmonary nodule interpretation

Approximately 30% of nodules are missed during the initial reading of chest radiographs. Eye-position recordings have shown that most nodules that are missed receive prolonged visual attention. A computer algorithm was developed that uses eye-position and gaze-duration times to identify locations on the chest image likely to contain missed nodules. These locations are highlighted on the displayed image to give visual feedback. The current study tested whether visual feedback was an effective aid to nodule detection. Six radiology residents searched 40 chest images for nodules while their eye-position and gaze-duration times were recorded. Half received displayed visual feedback and half were given a second view without feedback. Two months later the two groups returned and viewed the images in the opposite condition to counterbalance for possible practice effects. Performance of readers who were given feedback showed an average of 16% improvement as measured by the alternative free response operating characteristic (AFROC) curve area, A1. Performance of the same readers given a second look without feedback did not improve.