| Objective:The energy spectrum CT image of rabbit drowning lung was analyzed by virtual anatomy technique based on energy spectrum.Based on the image of rabbit drowning lung,the imaging images of material density and effective atomic number were obtained by energy spectrum display,and the image was quantified as the corresponding value of base material,which combined with CT value to reflect the characteristic change law of drowning lung,in order to provide a new reference for the identification of drowning.Methods:.Take 30 liters of lake water from the lake(imitating real drowning liquid)and place the water in a white transparent plastic bucket with a capacity of 60 liters as experimental drowning liquid.The experimental rabbits were weighed and numbered sequentially and scanned with 24 rows of 32-layer energy spectrum CT(Precision32)of Kaiying Medical company limited.Rabbits were divided into four groups: anaesthesia with 10% chloral hydrate at the dose of 1ml/kg intravenously injected into the ear margin followed by CT scanning(blank control group),excessive anaesthesia death group(death control group),immersion of 30 min at 0.5 m underwater(postmortem water intake group)and 1min at 0.5 m underwater.It was proposed that the surface of the water sank back into the same depth of water for 30 seconds and repeated several times until the experimental animals drowned(drowning group).Using CAMPOIMAGING system,peak analysis-energy spectrum display and analysis of lung base substance pairs and effective atomic number images of each experimental group,and base substance values and CT values of the special highlighted areas on the images were analyzed.At the end of the scan,the lungs of the rabbits in each experimental group were routinely dissected and observed and the samples were examined under histology.Results:The experiment showed that the CT images of the lungs in the drowning group showed characteristic ground glass-like changes,while no obvious abnormalities were found in the corresponding parts of the postmortem water intake group and the control group.A large number of water-bearing bright areas can be clearly seen in the images of the basic material of the lungs in the drowning group,and scattered and distributed in the postmortem water intake group,and there are no highlight areas in the death and blank control group,and respiratory movement artifacts can be seen in the blank control group.the effective atomic number image of the drowning group has a dense mixed high-density shadow and completely coincides with the underwater line,which can confirm that the main component of the drowning fluid is water.There were high and low density shadows in the lung effective atomic number images in the postmortem water intake group,some high density areas had high water content probability,and others did not contain water;there were a large number of low density shadows and a small amount of mixed density shadows in the death control group,but all of them did not contain water;the effective atomic number images in the blank control group showed uniform low density shadow and respiratory movement artifact and no water.The lung imaging images of each experimental group were quantified into base material value and CT value by energy spectrum CT scanning.The values of lung base material and CT were 952.65 ±92.53 and-361.59 ±68.62 in drowning group,412.77 ±81.49 and-608.72 ±55.62 in postmortem water intake group,379.40 ±50.48,-595.93 ±74.28 in death control group,and381.80 ±26.20,-603.65 ±48.49 in blank control group.The corresponding value of lung basic material in drowning group was significantly higher than that in blank group,postmortem control group and postmortem water group(p <0.05),but there was no significant difference between postmortem water intake group,death control group and postmortem water group(p > 0.05).The lung CT value of drowning group was significantly higher than that of blank control group,death control group and postmortem water intake group(p < 0.05).The CT values of rabbits in postmortem water,blank and death control group had no significant difference.There was no significant difference between postmortem water intake,blank and death control group(p > 0.05).The results of autopsy,microscopic histological observation and energy spectrum analysis showed that the lung imaging changes of rabbits in each experimental group were consistent.Conclusion:On the basis of the images of drowned lungs,the special imaging features such as water-bone material pair images and effective atomic number images of drowned rabbits were obtained by energy spectrum analysis.The combination of base material value,CT value and effective atomic number can further effectively reflect the specific changes of drowning lung numerically,which provides a new reference for the imaging study of drowning. |
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