These findings suggest a subtle, pre-existing hippocampal malformation that may facilitate febrile convulsions and contribute to the development of subsequent HS.
Because mean intracranial pressure (ICP) levels in patients without brainstem lesions were similar to those in patients with brainstem lesions, the authors conclude that it was not mainly increased ICP that accounted for the high mortality rates in patients with brainstem lesions. The authors also conclude that brainstem lesions are more frequently found in severe head injury than previously reported in studies based on neuropathological or CT scanning data. Early MR imaging after head injury has a higher predictive value than CT scanning.
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.
There is little knowledge on the morphology of the brain stem in survivors of head injury, as CT fails to shown brain stem lesions, and neuropathological data is only available from autopsies. As magnetic resonance imaging (MRI) sheds new light on morphological lesions of the brain, the authors investigated 100 patients with a severe head injury. MRI was performed in a prospective study within the first seven days after head injury while the patients were still in coma and on ventilation. Relating the location of the lesions as depicted by MRI with the initial CT scan and outcome, death appeared to be closely linked to the phenomenon of bilateral pontine lesions. The extent of supratentorial lesions had no bearing on survival at all in the absence of brain stem lesions. Altogether the brain stem was affected in 52%. Obviously the occurrence of bilateral upper pontine lesions is of highest predictive value for a fatal outcome. Severe destruction of supratentorial white matter as demonstrated by MRI is not related to increased mortality, as long as the brain stem is spared.
Though mammography is one of the most sensitive methods to detect breast cancer, the benefit of the mammography screening programmes is still not clearly proven. One of the reasons is the radiation dose delivered by the examinations. Simulations of the radiation transport based on realistic breast phantoms are a useful tool to estimate the dose for the risk relevant parenchymal tissue. Specimens of real breasts have been fixated using a specially designed process while being compressed as in mammography. They have been scanned using the high-resolution mode of a CT. A segmentation has been carried out by assigning the voxels to different tissues. The resulting voxel phantom allows the assessment of tissue doses by Monte-Carlo calculations and can be used to simulate the diagnostic outcome of different imaging procedures. Three different tissues were separated: skin, adipose and 'breast tissue'. This allows reasonable calculations of the average glandular doses in mammography.
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