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Biomedical subjects

D Magid

Publications and source records attributed to D Magid.

At least 19 recordsLinked to original sources
PubMed1992

Prevention of Lyme disease after tick bites. A cost-effectiveness analysis.

BACKGROUND: In areas of endemic disease, the probability of Lyme disease after a tick bite ranges from about 0.012 to 0.05. Early treatment with oral antibiotics prevents most complications of Lyme disease, but antibiotics are generally not prescribed until rash or other symptoms develop. METHODS: We used decision analysis to evaluate the outcomes, costs, and cost effectiveness of three alternative strategies to treat patients bitten by ixodes ticks in areas of endemic Lyme disease: empirically treat all patients with two weeks of doxycycline, treat only patients in whom erythema migrans develops, and treat only patients with erythema migrans or a positive serologic test for Lyme disease one month after exposure. RESULTS: Empirical treatment is the least expensive strategy and results in the fewest cases of Lyme disease and the fewest complications when the probability of Borrelia burgdorferi infection after a tick bite is 0.036 or higher. For probabilities of infection below 0.036, empirical therapy prevents most major complications, sequelae, and adverse events, but it incurs additional minor complications, especially as the probability of infection falls below 0.01. CONCLUSIONS: Empirical treatment of patients with tick bites is indicated when the probability of B. burgdorferi infection after a bite is 0.036 or higher, and this treatment may be preferred when the probability of infection ranges from 0.01 to 0.035. When the probability of infection after a tick bite is less than 0.01, empirical therapy is not warranted.

Animals↗
PubMed1992

Examination of the pathologic anatomy of ankle fractures.

A prospective study of the translational and rotational displacement of the lateral malleolus in ankle fractures was carried out utilizing roentgenographic techniques. Twenty-six ankle fractures in 25 patients were studied using both routine plain films and CT scanning with two- and three-dimensional multiplanar reconstruction. Eighty-one percent were Lauge-Hansen supination-external rotation type injuries. Overall, 21 fractures did not involve the medial malleolus. Initial talar shift was less than or equal to 2 mm in 15 fractures. Although all patients exhibited external rotation deformities of the lateral malleolus on plain films, only one fracture was found to possess any degree of external rotation relative to the talus. The proximal fibula was seen on CT scans to have increased internal rotation with respect to the tibia in 19 cases. One patient had a slightly externally rotated proximal fibula; the remainder appeared normally aligned. The displacements measured by the CT scans at the talofibular articulation were compared with the standard plain film measurements. The displacements at the distal lateral malleolus were consistently overestimated by the plain roentgenograms, presumably because the capsular and ligamentous attachments to the distal fibula limit malleolar displacement. The talocrural angle, determined on both plain films and CT scans, was also not found to be a sensitive measure of fibular shortening nor of the severity of the fracture. The results of this study suggest that, in an isolated lateral malleolar ankle fracture, the apparent external rotation of the fracture fragment is relative only to the proximal fibula and is not associated with derangement of the talofibular articulation. Based on these mechanical considerations, surgical intervention for such fractures may not be necessary. This hypothesis is consistent with previous long-term clinical studies.

Adolescent↗
PubMed1992

Musculoskeletal infections in patients with AIDS: CT findings.

The CT appearances of various musculoskeletal infections found in patients with AIDS are illustrated. Recognition of these infections is important for management of patients, but conventional laboratory tests may be inadequate in screening for infection or confirming the response of the host to therapy. As a screening examination for patients with AIDS, CT can suggest or confirm the presence of musculoskeletal infections even when infection has not been suspected.

Abscess↗
PubMed1992

Lymphoma of bone, muscle, and skin: CT findings.

Lymphoma can involve any part of the musculoskeletal system. Primary musculoskeletal lymphoma is rare but can occur in bone (reticulum cell sarcoma) or in the skin and subcutaneous tissues (mycosis fungoides). Secondary involvement in the musculoskeletal system is more common and can have a variety of radiologic findings. The definitive diagnosis of musculoskeletal lymphoma, however, is difficult to make by using imaging criteria alone. Any part of the musculoskeletal system can be involved and, therefore, a wide variety of primary and secondary neoplasms or inflammatory processes may have similar radiologic findings. The main differential diagnostic considerations, depending on the age of the patient and the clinical presentation, include osteosarcoma, Ewing's tumor, metastatic disease (from breast, lung, thyroid, or renal primary lesions), as well as chronic osteomyelitis or myositis. Primary and secondary bone lymphoma can be indistinguishable radiologically and histologically, but modern imaging techniques allow more accurate differentiation of primary from secondary bone involvement. This pictorial essay illustrates the CT findings of primary and secondary lymphoma involving bone, muscle, and skin and subcutaneous tissues.

Bone Neoplasms↗
PubMed1991

Pulmonary Aspergillus chest wall involvement in chronic granulomatous disease: CT and MRI findings.

Pulmonary Aspergillus infection in patients with chronic granulomatous disease tends to involve the chest wall and consequently carries a high mortality rate. We report the findings of computed tomography (CT) and magnetic resonance imaging (MRI) in three such cases. One patient underwent both CT and MRI, one, CT only, and one, MRI only. In all three, both CT and MRI demonstrated pulmonary consolidations with direct extension to the adjacent chest wall. In both patients who were examined by CT, scans revealed permeative osteolytic changes of adjacent rib or spine compatible with osteomyelitis. In both patients who were examined by MRI, adjacent chest wall involvement was depicted on T1-weighted images and showed increased signal intensity on T2-weighted images. In one of these patients, the chest wall lesion was well defined on T2-weighted images, an appearance compatible with abscess. Epidural extension was demonstrated on MRI in the other patient, who later developed paraparesis. We suggest that CT and MRI have a complementary role in evaluating chest wall invasion by pulmonary Aspergillus infection in chronic granulomatous disease.

Adolescent↗
PubMed1991

The use of graphic design in an interactive computer teaching program.

The widespread diffusion of affordable computers into the scientific and educational community has provided the opportunity to design medical and scientific teaching programs illustrated either by hand or by utilizing commercially available software and manipulating existing computer generated images. The medical illustrator can provide the ideal aesthetic link between text format information and the visual representation of such knowledge in a concise presentation format. The availability of interactive multimedia programs has given the medical illustrator an environment to create and enhance Hypermedia designed specifically for the purpose of medical education. This paper will focus on the incorporation of illustration and screen design into "CT The Game," an experimental medical teaching program currently being developed in the Johns Hopkins Body CT Imaging Laboratory. The program is designed to provide an enjoyable approach to learning Computed Tomography (CT), and is directed toward an audience of medical students, residents, and fellows.

Computer Graphics↗
PubMed1991

Data base management in radiology: a simplified approach.

The increasing availability of personal and departmental computers in radiology departments has led to increasing interest in data management. Data base management software must be system compatible, simple, and flexible to insure its acceptance and constant use. Once in place, such a system streamlines the daily documentation of interesting cases for conference, follow-up, research, and quality assurance. The authors have developed such a data base program for tracking computed body tomography cases in their department, which can be run as a portable computer to maximize ease of access and therefore usage.

Database Management Systems↗
PubMed1991

The perception of mirror-reflected objects.

In what ways and under what conditions does an object appear to differ from its enantiomorph (its mirror reflection)? This 'mirror question' or its popular counterpart, "Why does a mirror reverse left and right but not up and down?" is frequently encountered, but an acceptable answer is not to be found in the literature. The question is approached as an experimental problem in visual psychophysics. A mirror optically reverses the axis perpendicular to its surface. What are the perceptual consequences of this stimulus transformation? This question is examined in four experiments by using stimuli of varying complexity and familiarity. Apparent reversals are demonstrated along right-left, front-back, top-bottom, and oblique axes, depending on the perceived asymmetries of the stimulus object. Perceived asymmetry is shown to depend both on structural asymmetries and on canonical axes and orientations defined by social convention. It is concluded that an object appears to differ from its enantiomorph by an apparent reversal along the axis of least perceived asymmetry. Implications for perceptual frames of reference and for the perception of symmetry are discussed.

Adult↗
PubMed1991

Sacral foramina: view at CT.

Conventional transaxial computed tomography (CT) is superior to plain radiography in depicting the sacrum. Because of the shape and orientation of the sacrum, CT provides oblique views of the structures of interest. With easily reproducible landmarks and standard transaxial CT data, orthogonal image sets can be produced that provide a true en face orientation matching the obliquity of the sacrum. This allows optimal visualization of the paired foramina and of the sacroiliac joints for better assessment of trauma, tumor, or inflammatory disease.

Humans↗
PubMed1991

Computed tomography of the hand and wrist.

CT plays a limited but distinct role in the evaluation of the hand and wrist. It is most useful in assessing bone and joint anatomy and has only a secondary role in soft tissue abnormalities. The clearest value of CT is in assessing trauma and post-traumatic complications, such as malunion, nonunion, or avascular necrosis, where careful attention to position and technique can yield important information not otherwise obtainable.

Fractures, Bone↗
PubMed1990

AIDS education in the emergency department.

The prevention of the spread of acquired immunodeficiency syndrome (AIDS) depends on an educated public reducing their risk of infection. To test the hypothesis that effective community AIDS education can be based in an emergency department, we designed and evaluated two educational interventions in a high-volume urban ED. A pretest/post-test design was used in which subjects were assigned to receive either an active education program, a passive education program, or no education program. Knowledge gains and self-reported risk-reduction behavior were evaluated by follow-up testing within a five-week period. The active and passive groups had significantly greater knowledge gains than the control group (P less than .001). Significantly greater reported reductions in high-risk behavior were found in both the active and passive groups compared with the control group (P less than .01). This study demonstrates that an ED-based AIDS education program can have a significant impact on improving knowledge and reducing self-reported risk behaviors.

Acquired Immunodeficiency Syndrome↗
PubMed1990

CT of malignant melanoma in the chest, abdomen, and musculoskeletal system.

Malignant melanoma is an aggressive neoplasm that can involve virtually every organ system. This article provides a review of the various appearances on computed tomographic (CT) scans of melanoma involving the chest, abdomen, and musculoskeletal system. Specific emphasis is placed on the typical and atypical CT manifestations of disease as well as the similarity of these findings to those for other disease entities. The importance of accurate staging of melanoma is stressed.

Abdominal Neoplasms↗
PubMed1990

Adult ankle fractures: comparison of plain films and interactive two- and three-dimensional CT scans.

Thirteen patients with 15 ankle fractures potentially requiring surgical reduction according to plain film criteria were studied with transaxial CT, from which static and animated interactive two-dimensional (2-D) images and animated volumetric three-dimensional (3-D) images were generated. CT criteria believed to parallel well-accepted plain film criteria for triage of ankle fractures were developed and applied. The tibiofibular, talofibular, and tibiotalar articulations were characterized and, where possible (nine cases), compared with the (presumably normal) contralateral ankle. Talocrural angle measurements were made on interactive coronal measurements and compared with standard plain film measurements. Fracture fragment displacement, rotation, and impaction were noted. Posterior tibial lip disruption was quantified. Information derived from the 2-D/3-D CT study led to cancellation of proposed surgery in three of the distal fibular fractures and in two distal tibial fractures. There was far less variation than anticipated between the talocrural angles of the injured and normal ankles, and both injured and normal ankles deviated significantly from the accepted standard of 84 degrees. Displacement at the level of the fibular fracture was a poor predictor of more distal disruption. Two-dimensional CT was found to provide anatomic detail and information superior to either plain film or 3-D CT; 3-D CT was preferred by the surgeons for final surgical planning and for integration of the 2-D data. CT altered management in five of the 13 patients studied, supporting our belief that 2-D/3-D CT can be of significant value in assessing ankle fractures.

Adolescent↗