| ObjectiveThe purpose of this study was to investigate the angiographic effect,overall CT image quality and biosafety of liquid gallium as a angiographic contrast agent in computed tomography angiography(CTA)of living rabbits compared with conventional iodinated X-ray contrast agent.It provides an objective evidence for the research and development of new CT angiography materials and the three-dimensional reconstruction of fine vascular network in tissues and organs.MethodsThirty female New Zealand white rabbits with body weight of 3.5 ～ 4kg were randomly divided into control group(n = 15)and experimental group(n =15).The control group was contrasted with ioversol,and the experimental group was contrasted with liquid metal gallium(purity> 99.99%).Hepatic artery angiography and abdominal enhanced CT were performed in both groups by femoral artery puncture.Two groups of CT image post-processing,area of interest delineation and measurement,and image quality assessment were performed by two experienced radiologists respectively,including:1)Maximum intensity projection(MIP)and volume rendering(VR)techniques for 3D vascular reconstruction of abdominal aorta and hepatic artery.2)The minimum imaging diameter of hepatic artery in MIP and VR three-dimensional images was measured.3)The mean CT values of liver parenchyma and abdominal aorta were measured with the Standard deviation(SD)of the corresponding liver parenchyma,and the CT values of hepatic artery in arterial phase were measured.The size,shape and position of the region of interest(ROI)in the same region were required to be highly consistent.4)The whole image quality of the two groups was evaluated by the rule of thirds.The average data measured by two physicians on the same experimental rabbit were collected for data statistics.The results include: 1)The absolute enhancement of liver parenchyma and abdominal aorta were calculated after ioversol and liquid metal gallium angiography compared with the normal.2)Calculate the difference of CT values of hepatic artery,abdominal aorta and enhanced liver parenchyma after enhanced examination with two contrast agents.3)Calculate the contrast noise ratio(CNR)of hepatic artery and abdominal aorta relative to hepatic parenchyma.Eight million U of penicillin was injected intramuscular for three days after the operation,and the diet,defecation and activity of each experimental rabbit were closely observed and recorded,and the contrast agent retention was observed by abdominal CT plain scan 24 hours after the operation.The values of Scr and BUN were detected at 72 hours after operation.The pathological changes of kidney were observed by HE staining.Results1.1)The minimum diameter of hepatic artery and absolute enhancement value of hepatic parenchyma in the experimental group(0.671 ± 0.080,21.333± 4.780)were lower than those in the control group(1.095 ± 0.087,86.500 ±4.850),and the difference was statistically significant(P < 0.01);2)Absolute enhancement value of abdominal aorta and CT difference between hepatic artery and abdominal aorta compared with enhanced liver parenchyma in the experimental group(2230.740 ± 417.701,462.807 ± 38.273,2197.367 ±416.607)HU,were significantly higher than those in the control group(173.780± 6.758,80.473 ± 8.448,75.240 ± 3.757)HU,and the differences were statistically significant(P < 0.01);3)The contrast noise ratio of hepatic artery and abdominal aorta in the experimental group(59.033 ± 10.072,277.277 ±53.512)was significantly higher than the control group(16.481 ± 2.896,15.411± 2.305)and the difference was statistically significant(P < 0.01).2.In the control group,the overall image quality was superior in 8 cases(53.33%),medium in 5 cases(33.33%)and inferior in 2 cases(13.33%);In the experimental group,0 cases(0.00%)were excellent,8 cases(53.33%)were good,and 7 cases(46.67%)were poor.Therefore,the rate of superior and medium image quality in the control group was higher than that in the experimental group and the difference was statistically significant(P < 0.05)。3.In the control group,5 cases(33.33%)had anorexia,2 cases(13.33%)had abnormal urine and feces,6 cases(40%)had decreased activity,and 0cases(0.00%)had contrast agent retention after 24 hours;In the experimental group,there were 9 cases(60%)of inappetence,8 cases(53.33%)of abnormal urine and feces,11 cases(73.33%)of reduced activity,and 15 cases(100%)of contrast agent retention after 24 hours.In conclution,the incidence of adverse events within 3 days after CT angiography in the experimental group was significantly higher than that in the control group and the difference between the two groups was statistically significant(P < 0.01).4.Compared with the control group,the serum levels of Scr and BUN in experimental group were significantly increased(P < 0.05);In the experimental group,renal injury was observed.Pathology showed that the renal tubular epithelial cells were partially shed and swollen,vacuoles were formed,glomeruli were atrophy,and the number of inflammatory cells and apoptosis increased.Conclusions1.Liquid metal gallium used as a contrast agent for blood vessels in living tissues can display finer blood vessel branch structures,and has high contrast between blood vessels and surrounding tissues,which facilitates CT reconstruction of the distribution of small blood vessel networks in tissues and organs,and helps to carry out clinical research on tiny blood vessels.2.The effect of liquid metal gallium on the peripheral parenchyma of the blood vessel in CT angiography is not obvious,there is metal ray artifact,and the overall CT image quality is poor.3.Under the same injection dosage,injection flow rate and scanning parameters,liquid metal gallium used as a CT vascular contrast agent,compared with ioverol,causes a higher rate of adverse reactions in the body and lower biological safety,and its toxic molecules need to be further developed research on the direction of mechanism. |
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