| With the development of technology,the diagnosis of dog and cat diseases tends to be specialized and standardized.Imaging examination techniques such as Multidetector Spiral CT are more and more accepted and selected by pet owners.In order to satisfy the pet owner for specialized disease examination,enhanced CT was fully used in the examination and diagnosis of tumors,blood vessels,spine and other diseases.CT enhanced scanning is applicable to liver vascular diseases such as intrahepatic or extrahepatic portal short circuit,angiosarcoma,and surgical pathways for tumor resection.Kidney diseases such as kidney tumors,ureteral ectopic,ureteral blockage,and assessment of kidney function all play a critical role.The success or failure of enhanced CT scan depends on the choice of delay time,but at present,most hospitals use the empirical fixed delay time.For animals of different ages,weights and breeds,there is a large error,and only the empirical delay time often cannot accurately capture the ideal shooting period.Therefore,increasing the number of scanning results in increased radiation dose of animals.Not good for animal welfare.The automatic tracking scanning technology of contrast agent can make up the difference in the delay time of contrast agent reaching target organ among different individuals,Reduce the dose of radiation from the scan.The success rate and accuracy of enhanced scanning were improved.This paper explores the delay time of the automatic tracking scanning scheme of contrast agent in dogs’ liver and kidney,so as to provide a feasible automatic tracking scanning scheme of contrast agent for clinical enhanced CT scanning of liver and kidney,and contribute to imaging diagnosis.After the dynamic volume scanning of the liver and kidney of 48 healthy beagle dogs,the corresponding time-density curve was generated,and the corresponding delay time of each stage was obtained by analyzing the curve.The delay time was applied to the automatic tracking scanning scheme of contrast agent,300 mg I/m L iodohexol solution and575 mg I/kg contrast agent dose were used.The flow rate was 3m L/s and 1m L/kg normal saline was injected at the same flow rate after the contrast agent was injected.The liver monitoring layer was located between the twelfth and thirteenth ribs,the kidney monitoring layer was placed in the first lumbar vertebra,and the ROI was placed in the abdominal aorta in this plane,with a threshold of 110 HU.3D reconstruction of each phase was carried out after shooting,and the delay time of the empirical method was adopted for shooting.After shooting,the shooting quality and success rate of the two methods were compared.Acute liver injury model was made and liver contrast agent automatic tracking scanning scheme was used to diagnose acute liver injury.Liver and kidney cases related to dogs were collected,and the obtained automatic follow-up scanning protocol of liver and kidney contrast agent was applied to the diagnosis of clinical cases.The delay time of canine liver contrast-enhanced CT was 7.3s in arterial phase,10 s in hepatic portal vein phase and 16.1s in liver parenchymal phase after reaching the threshold.The delay time of canine renal contrast-enhanced CT was 7.5s in arterial phase,2.5s in corticomedullary phase,and 20 s in nephrographic phase after reaching the threshold.In dogs with acute hepatitis,the CT value of hepatic parenchyma decreased in non-enhanced scan,arterial phase,hepatic portal vein phase and liver parenchymal phase compared with normal.Among them,the CT value of hepatic parenchymal in the first two days after acute liver injury had the most significant decrease in hepatic portal vein phase,and the CT value decreased by 40 HU compared with normal.The density of hepatic parenchyma decreased in the eye view,and the image may be accompanied by low-density ascites,obvious liver paging,uneven enhancement of hepatic parenchyma and other typical images of acute liver injury. |
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