CT-based measurement of lung volume and attenuation of deceased
Master thesis in Biomedical Engineering by Elin Sylvan
AbstractWhen someone is suspected to have died from drowning an autopsy is carried out. There are no characteristic signs for drowning. The diagnosis relies primarily on critical examination of the subject’s individual characteristics, circumstances and postmortem macro- and micropathologic changes. Above all, the lungs are studied and the lung volume is investigated. Because of the difficulties in concluding whether a person has drowned or not, it is interesting to investigate if there are differences between drowned and other deceased. Information that could be relevant for postmortal diagnosis of drowning was studied. With postmortal CT images lung volume, mean attenuation, anterior-posterior difference, lung density profile and amount of water within the lungs were investigated. This report also evaluates three examples of software that calculates lung volume from postmortal CT images: Siemens’ Syngo Pulmo CT, Siemens‘ Volume Evaluation and GE Medical Systems’ Volume Viewer. The method used at autopsy was also studied. The repeatability and validity were tested and sources of errors identified. Repeatability and validity for the three tested types of software were acceptable, while the method used at autopsy had to be improved. The study also showed that lung volume related to length, anterior-posterior difference and lung density profile seemed to vary between the two groups, drowned and other deceased. The three measures might conclude whether a person has drowned or not.
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