Skeletal surveys for child abuse: comparison of interpretation using digitized images and screen-film radiographs.

OBJECTIVE: The objective of our study was to compare child abuse detection using screen-film radiographs and their digitized images displayed on a computer workstation. MATERIALS AND METHODS: Skeletal surveys of 20 consecutive child abuse patients whose abuse was clinically proven by a combination of history, physical and radiographic findings, and social work history, and 20 consecutive control subjects were evaluated. Three radiologists rated both the screen-film radiographs (400-speed, double-emulsion film) and their digitized images displayed on a workstation (2K x 2K resolution) using a six-point ordinal scale for suspicion of child abuse, fracture detection, and image quality. The rating response was analyzed using multiobserver-multicase receiver operating characteristic analysis of variance. The McNemar test was used to evaluate differences between imaging techniques and between diagnoses made using each imaging technique and clinically proven child abuse. RESULTS: The area under the receiver operating characteristic curve for screen-film radiographs was 0.934+/-0.025 and for digitized images was 0.922+/-0.013. This difference was not significant (p = .658); however, two observers significantly underestimated the child abuse diagnosis with digitized images (p = .02). In a review of the false-negative child abuse diagnoses, observers failed to recognize characteristic metaphyseal fractures (10 observations) and rib fractures (five observations) on digitized images that had been recognized on screen-film radiographs. Mean image quality was rated significantly lower (p < .0001) and interpretation time was significantly longer (75 sec; p < .001) for the digitized images than for screen-film radiographs. CONCLUSION: The characteristic types of fractures that were not identified on the digitized images, lower image quality, and longer interpretation time raise concern that digitized images may not be adequate for interpretation of suspected child abuse.

Degradation of surfactant lipids and surfactant protein A by alveolar macrophages in vitro.

Pulmonary surfactant is synthesized and secreted into the airspaces by the alveolar type II cell. After it is secreted, surfactant undergoes a series of poorly understood transformations resulting in formation of a surface tension-reducing surface at the air-liquid interface. The by-products of the surface film and/or other products of surfactant metabolism are eventually cleared from the alveolar space. Both the alveolar type II cell and the macrophage are thought to be involved in surfactant clearance and have been shown to internalize surfactant lipid in vitro. The goal of the current investigation was to characterize further and to quantitate the role of the macrophage in surfactant clearance by investigating the uptake and metabolism of surfactant lipids and surfactant protein A (SP-A) by macrophages in vitro. SP-A enhanced the uptake of lipids by macrophages in a time-, temperature-, and concentration-dependent manner. In contrast, neither of the collagen-like proteins SP-D or C1q enhanced the uptake. Phosphatidylcholine was rapidly degraded by macrophages and the degradation occurred both in the presence and absence of SP-A. In addition, macrophages degrade SP-A by a process that is time- and temperature-dependent. These results and calculations of uptake and degradation rates suggest that macrophages may contribute significantly to the process of surfactant clearance.

MR detection of white matter disease of the brain in patients with HIV infection: fast spin-echo vs conventional spin-echo pulse sequences.

OBJECTIVE: Although fast spin-echo images and slower spin-echo images have similar contrast characteristics, the two techniques have not yet been shown to be equivalent in all aspects of brain imaging. To determine if the two sequences are equivalent, we compared detection of white matter lesions, image quality, and artifact degradation on fast spin-echo and spin-echo proton density-weighted and T2-weighted MR images of the brain in prospectively selected patients who were seropositive for HIV. SUBJECTS AND METHODS: Fast spin-echo and spin-echo MR images of the brain were obtained in 153 consecutive subjects. The images were reviewed independently by three experienced neuroradiologists. The size, number, and location of white matter lesions were compared for the two techniques. Image quality, motion artifact, CSF flow artifact, and gray-white matter differentiation were graded on a five-point scale. RESULTS: No statistical difference was found in gray-white matter differentiation. Overall image quality, CSF flow artifacts, and motion artifacts were slightly worse on the fast spin-echo images (p < .05). Although some variability existed in the detection of lesions less than 5 mm in diameter, the differences was small, and all larger lesions were detected by both techniques. Agreement between fast spin-echo and conventional spin-echo techniques was nearly exact with respect to characterizing findings in brain as either normal or abnormal. CONCLUSIONS: Fast spin-echo and spin-echo MR of the brain produce images of similar quality and show white matter lesions equally well. These results support the replacement of slower, conventional spin-echo pulse sequences with faster fast spin-echo sequences.

Pulmonary surfactant protein A stimulates chemotaxis of alveolar macrophage.

Pulmonary surfactant modulates several functions of alveolar macrophages including phagocytosis, killing, and chemotaxis. We hypothesized that the reported stimulatory effect of surfactant on macrophage migration was mediated by one of the surfactant proteins, SP-A. We found that macrophage migration was stimulated by SP-A in a concentration-dependent manner. A concentration of 105 micrograms SP-A/ml enhanced migration approximately 10-fold. Heat treatment or reduction and alkylation of SP-A reduced its stimulatory effect. A checker-board analysis showed that SP-A stimulated migration primarily by enhancing chemotaxis (directed movement) rather than chemokinesis (random movement). The interaction of SP-A with macrophages may be mediated at least partly by the collagen-like domain of SP-A. We speculate that SP-A may play a multifunctional role in regulating pulmonary immune response by stimulating multiple macrophage functions.