The statistically significant correlations between the 4 groups of severe head injury patients, as identified by MRI, with mortality and outcome of survivors justify a new classification based on early MRI findings.
This work confirms the presence of autonomous respiratory centers within the caudal medulla oblongata that allows sufficient adequate respiration in coma. Respiration ceases in the presence of a bilateral lesion of this area.
In addition to comparing the image quality of the different systems, this study shows that the performance of a radiographic system depends on the structure to be analyzed. The modified ROC (ms-ROC) provides valid results with less effort.
Introduction: Traumatic brain stem lesions (tBSL) in children are thought to be a rare phenomenon. This prospective study analyzed the frequency and significance of such lesions on early magnetic resonance imaging (MRI) after severe head injury, since CT fails to demonstrate these lesions. Methods: In 30 consecutive children comatose after head injuries, MRI was performed within 8 days of the injury. Results: The incidence of tBSL was 60%. When the lesion affected the pons or caudal portions of medulla oblongata bilaterally, mortality was 100%. The presence of tBSL significantly correlated with the duration of coma and the categories of outcome, as indicated by the Glasgow Outcome Score. The frequency and the distribution of tBSL in children were similar to adults. Conclusion: Magnetic resonance imaging appears to be of high predictive value after severe pediatric head injuries.
There are many aspects that influence and deteriorate the detection of pathologies in X-ray images. Some of those are due to effects taking place in the stage of forming the X-ray intensity pattern in front of the x-ray detector. These can be described as motion blurring, depth blurring, anatomical background, scatter noise and structural noise. Structural noise results from an overlapping of fine irrelevant anatomical structures. A method for measuring the combined effect of structural noise and scatter noise was developed and will be presented in this paper. This method is based on the consideration that within a pair of projections created after rotation of the object with a small angle (which is within the typical uncertainty in positioning the patient) both images would show the same relevant structures whereas the projection of the fine overlapping structures will appear quite differently in the two images. To demonstrate the method two X-ray radiographs of a lung phantom were produced. The second radiograph was achieved after rotating the lung by an angle of about 3°. Dyadic wavelet representations of both images were regarded. For each value of the wavelet scale parameter the corresponding pair of approximations was matched using the cross correlation matching technique. The homologous regions of approximations were extracted. The image containing only those structures that appear in both images simultaneously was then reconstructed from the wavelet coefficients corresponding to the homologous regions. The difference between one of the original images and the noise-reduced image contains the structural noise and the scatter noise.
The results of the patient VGA study and the phantom ROC study are similar and considered valid. The new digital imaging systems with flat panel detector and transparent imaging plate provide the best image quality of the tested radiographic devices for chest imaging, assuming that all system components are attuned and optimized for the type of structure to be detected. Image processing is of primary importance for system optimization.
A halving of the patient dose is possible with acceptable results for the image quality. The effect of an improved image processing remains to be evaluated. The patient entrance dose is suitable for an evaluation of a radiographic detector and especially for a dose-referred comparison of digital X-ray units.
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