Functional imaging method of biological electrical characteristics based on magneto-acoustic effect gives valuable information of tissue in early tumor diagnosis, therein time and frequency characteristics analysis of magneto-acoustic signal is important in image reconstruction. This paper proposes wave summing method based on Green function solution for acoustic source of magneto-acoustic effect. Simulations and analysis under quasi 1D transmission condition are carried out to time and frequency characteristics of magneto-acoustic signal of models with different thickness. Simulation results of magneto-acoustic signal were verified through experiments. Results of the simulation with different thickness showed that time-frequency characteristics of magneto-acoustic signal reflected thickness of sample. Thin sample, which is less than one wavelength of pulse, and thick sample, which is larger than one wavelength, showed different summed waveform and frequency characteristics, due to difference of summing thickness. Experimental results verified theoretical analysis and simulation results. This research has laid a foundation for acoustic source and conductivity reconstruction to the medium with different thickness in magneto-acoustic imaging.
Acoustics ; Computer Simulation ; Diagnostic Imaging ; Electricity ; Electrophysiological Phenomena ; Humans ; Magnetics ; Models, Theoretical

Magnetoacoustic tomography (MAT) has some advantages such as high sensitivity and high spatial resolution. The generating mechanism of acoustic source is the research foundation of forward and inverse problems. A coustic signals were respectively simulated by using monopole and dipole radiation theory in the experimental conditions, then the differences between their acoustic pressures were discussed, and furthermore the contrast and validation were conducted by physical experiments in this study. The physical experimental results showed that acoustic waveform of MAT had a certain directivity and therefore they indicated that dipole model showed higher approximation to the real facts than monopole model. It can be well concluded that this research has cardinal significance for the accurate algorithm of MAT.
Acoustics ; Algorithms ; Tomography ; methods

Objective To establish a rat model of associating liver partition with portal vein ligation for staged hepatectomy (ALPPS) and evaluate the liver function after surgery.Methods Fifty male SD rats were randomly divided into two groups: experimental group (ALPPS group) and control group (PVL group).Selective portal vein ligation in PVL group was performed on the caudal lobe, left lateral and left median lobes, while the right lobe, the right median lobe was preserved to regenerate.ALLPS group was treated in the same way as PVL group, but also underwent liver partition in situ.After surgery, 5 rats were sacrificed on day 1, 3,7, 10 and 14 in each group to observe the weight of body and the right median lobe,respectively.The venous blood and liver tissue were obtained for testing alanine aminotransferase (ALT),aspartate aminotransferase (AST), serum albumin (ALB), total bilirubin (TBil) and observing the histological changes in liver injury after surgery.Results After surgery, the body weight decreased progressively, but then increased in both groups.Since the first day after surgery, the body weight began to decrease,reached the lowest value on 3 d, and then on day 7 the body weight in PVL group returned to preoperative levels.However, the body weight was still lower than that before surgery [(3.7 ± 2.7) ％ vs (-3.0 ± 1.9)％, P＜0.05].On day 3, 7, 10 and 14, the hepatic regeneration rate (HRR) of the fight median lobe in ALPPS group was obviously higher than that in PVL group (P ＜ 0.05).On day 1, the serum ALT and AST levels in two groups were elevated dramatically and then gradually decreased, which in ALPPS group were significantly higher than those in PVL group (P ＜ 0.05).There were no significant differences at other time points.On day 1 and 3, the serum ALB in ALPPS group was obviously lower than that in PVL group [(25.4±1.7)g/Lvs (31.4±1.5)g/L, P＜0.05;(25.0±2.0)g/Lvs (31.8±1.5)g/L, P＜ 0.05], respectively.More focal necrosis of liver were observed in ALPPS group on day 1, which were more than those in PVL group.Conclusions This method could successfully establish a ALPPS rat model and proved that ALPPS could induce accelerated hepatic regeneration and more severe early hepatocyte injury compared with PVL.This ALPPS experimental model provides a basis for further research on ALPPS, especially for clarifying the mechanisms of liver regeneration and tumor recurrence, and exploring the reasons for various ALPPS related complications, which play a significant role in its clinical application.

Objective To investigate the effect of portal vein ligation combined with in situ splitting on liver regeneration in rats .Methods Seventy-five healthy male Sprague-Dawley rats were selected and randomly assigned into sham operation group ( S) , portal vein ligation group ( PVL) and portal vein ligation combined with in situ splitting group ( ALPPS) .On 1 d, 3 d, 7 d, 10 d, 14 d after operation , the hepatic regeneration rate ( HRR) of right median lobe was calculated , the serum alanine aminotransferase ( ALT) , aspartate aminotransferase (AST), IL-6, HGF, VEGF were detected.mRNA of IL-6, HGF, TNF-α, TGF-βwas assayed by real-time PCR, and the hepatic proliferating cell nuclear antigen ( PCNA) labeling index was evaluated by immunohistochemistry .Results Comparing with PVL group , the HRR of the right median lobe obviously increased on day 3, 7, 10 and 14 in ALPPS group (P<0.05), and ALT and AST level were increased on 1 d (P<0.05).On day 1 and 3, the content of serum IL-6, HGF and VEGF were all in-creased in ALPPS group [(70.7 ±14.6) pg/ml vs.(134.2 ±31.4) pg/ml; (0.70 ±0.04) ng/ml vs. (0.74 ±0.02) ng/ml;(82.1 ±12.6) pg/ml vs.(103.5 ±14.7) pg/ml], respectively (P<0.05).The mRNA expression of IL-6, HGF, TNF-α, TGF-βand the PCNA labeling index were also increased in ALPPS group in comparison with those in PVL group on day 1 and 3 (P<0.05).All the indexes in the two groups were all higher than those in the group S ( P<0 .05 ) .Conclusions Portal vein ligation combined with in situ splitting could significantly enhance liver regeneration .The possible mechanisms were related to the inflammation reaction and stress response caused by in situ splitting and up-regulation of cytokines in the regenerating lobe after portal vein ligation combined with in situ splitting , especially IL-6, HGF and TNF-α.

Objective To design a new frequency domain magnato-aoustic imaging system to image the conductivity of medium.Methods A continuous sine wave signal was adopted to stimulate the MAT signal. The lock-in technique was applied to measuring the amplitude and phase of the magneto-acoustic signal. The drive control program of the imaging system was designed using virtual instrument tools. The experiments were conducted on the phantom made of coper wire.Results The amplitude precision was improved up to 10-7 Pa, while the system could locate the sonic source with locating precision of millimeter.Conclusion A new magneto-acoustic imaging system is proposed with high locating precision as well as low frequency excitation, which is significative to the study on the sonic source theory and improvement of the imaging precision.

Postm ortem chem istry is becom ing m ore and m ore essential in routine forensic pathology and has m ade considerable progress over the past years. B iochem ical analyses of vitreous hum or, blood, urine and cerebrospinal fluid m ay provide im portant inform ation in determ ining the cause of death or in elucidating forensic issues. Postm ortem chem istry m ay be essential for the determ ination of cause of death w hen m orphological m ethods (diabetes m ellitus, alcoholic ketoacidosis and electrolytic disorders) cannot detect the pathophysiological changes involved in the death process. It can also provide m any in-form ation in other forensic situations, including m yocardial ischem ia, sepsis, inflam m ation, infection, ana-phylaxis and horm onal disturbances. T he m ost recent relevant research advances on glucose m etabolism , liver function, cardiac function, renal function, sepsis, inflam m ation, infection, anaphylaxis and horm onal aspect are hereby review ed.

Objective To explore the application value of multi-slice spiral computed tomography (MSCT) in traffic accidents through observing and analyzing the injury features of the accidents. Methods Two fatal cases caused by traffic accidents were fully examined using MSCT, 3D imaging reconstruction and angiography through cardiac puncture. The features of traffic injury mechanism were analyzed through combination of MSCT and postmortem external examination. Results In case 1, right cardiac rupture was found by MSCT and angiography through cardiac puncture. The cause of death was cardiac tam-ponade and right ventricular rupture due to the crush injury of chest in the traffic accident. In case 2, splenic rupture and intra-abdominal hemorrhage was found and caused by injury of left trunk by MSCT. The cause of death was hemorrhage and traumatic shock. Conclusion MSCT could observe skeletal in-jury, soft tissue injury, and hematologic disorder well. The combination use of MSCT and angiography through cardiac puncture provided assistance to the diagnosis of cardiovascular system injury.

Objective To analyze the clinical features of children with EV71 positive hand,foot,and mouth disease(HFMD)and EV71 vaccination,and to explore the relationship between the occurrence of severe disease and the preventive effect of EV71 vaccine.Methods From January 1,2020 to December 31,2022,the clinical data of 131 children with HFMD diagnosed with EV71 infection in Kunming Children's Hospital were retrospectively analyzed.The stool samples of patients with clinically confirmed HFMD were selected for enterovirus nucleic acid detection.The clinical data and EV71 vaccination status of children with universal enterovirus positive and EV71 positive HFMD were analyzed.Results Among the 131 positive cases detected,there were 116 mild cases and 15 severe cases.Among the 80 children who received phone consultations about their EV71 vaccine status,17 were vaccinated,and 63 were not vaccinated.The vaccinated children were all mild cases,while among the unvaccinated children,6 were severe cases.From 2020 to 2022,the period from April to September each year is the peak period for detecting EV71-positive hand,foot,and mouth disease(χ2 = 125.705,P = 0.000).The positive detection rate for children under 1 year old and over 5 years old was higher than that for children aged 1 to 5 years(χ2 = 8.765,P = 0.033),and there was no significant difference in the positive detection rate between boys and girls(χ2 = 1.221,P = 0.269).Conclusion EV71 vaccine is of great significance in reducing the occurrence of severe cases.Combined with the current low vaccination rate in Kunming,Yunnan Province,it is suggested that relevant institutions should continue to increase the publicity of EV71 vaccination.

Objective:To explore the clinicalfactors related to allograft fibrosis after pediatric liver transplantation.Methods:The clinical data were respectively analyzed for 94 pediatric recipients from January 2013 to December 2016 at Tianjin First Central Hospital.The Patients were assigned into fibrotic and non-fibrotic groups based upon the results of protocol liver biopsies. Univariate and multivariate Logistic regression analyses were performed for examining the risk factors of fibrosis after pediatric livertransplantation. Then Logistic regression model was established to obtain the predicted value of combined predictive factors.Thereceiver operating characteristic curve (ROC) was conducted to evaluate the predictive value of combined predictive factors.Results:A total number of 54(57.5%) patients occurred fibrosis among the 94 patients. There weresignificant differences in cold ischemia time (Z=2.094), warm ischemia time (Z=2.421), biliary stricture( χ2=4.560), drug-induced liver injury ( χ2=7.389), hepatic artery thrombosis and rejection ( χ2=6.955)between two groups ( P<0.05). Logistic regression analysis showed that cold ischemia time (OR=1.003, 95%CI: 1.000~1.007, P=0.044), biliary stricture(OR=6.451, 95%CI: 1.205~33.295), rejection(OR=2.735, 95%CI: 1.057~7.077)and drug-induced liver injury (OR=4.977, 95%CI: 1.207~20.522, P=0.026) were independent risk factors for fibrosis 5 years after liver transplantation. The area under the ROC curve was 0.786(95%CI: 0.691~0.881), for predicting patient outcome.If using 0.311as a cutoff Value, the sensitivity was 90.70%, and the specificity was 60.00%. However, through the ROC curve comparison, there was statistical significance between combined predictive factors and the other independent risk factors ( P>0.05). Conclusions:The incidence of fibrosis 5 years after pediatricliver transplantation is 57.5%. Prolonged cold ischemia time, biliarystricture, rejectionand drug-induced liver injury after liver transplantation are independent risk factors for fibrosis 5 years after pediatric liver transplantation.And the combined predictive factors have a high predictive value forallograftfibrosis.

Objective To explore the clinical efficacy of pediatric blood type incompatible living donor liver transplantation. Methods The clinical data from 242 cases of pediatric living donor liver transplantation recipients were retrospectively analyzed. Recipients were assigned to group A (ABO-identical group, n=165), group B (ABO-compatible group, n=42) and group C (ABO-incompatible group, n=35) according to the blood type compatibility between the recipients and the donors. The occurrence of postoperative complications and development of postoperative donor specific antibody (DSA) among the 3 groups were observed and compared. And the blood type distribution of donors and recipients and development of erythrocyte antibodies in group C were analyzed. The survival situation of recipients after liver transplantation was compared among the 3 groups. Results There was no significant difference in the incidence of complications among the 3 groups(all P > 0.05). DSA was dominated by human leukocyte antigen (HLA) Ⅱ antibodies after liver transplantation, mostly anti-HLA-DR and anti-HLA-DQ. The postoperative erythrocyte antibodies for liver transplant recipients in group C were dominated by IgM, with titers ≤1:2 for all. The differences in postoperative survival rates were not statistically significant among 3 groups(all P > 0.05). Conclusions Pediatric blood type incompatible living donor liver transplantation is a safe and effective treatment, which can effectively expand the source of liver transplant donors and save the children's lives.