Objective To investigate the feasibility of low-c oncentration iso_osmolar contrast agent together with low tube voltage and iterative reconstruction algorithm in rabbit liver computed tonography (CT) perfusion imaging.Methods A total of 15 bealthy New Zealand rabbits were scanned twice of liver CT perfusion scans each with 24 hours interval.The first scan (routine group) was acquired at 100 kV and 100 mAs with ultravist (370 mg/ml),while the second (double low group) was acquired at 80 kV and 100 mAs with iodixanol (270 mg/ml) at 24 hours after the first scan.The obtained images were reconstructed with filtered back projection (FBP) and adaptive iterative dose reduction (AIDR-3D)algorithms in the controlled and experimental groups,respectively.The perfusion parameters including hepatic artery perfusion(HAP),portal vein perfasion(PVP),hepatic perfusion index(HPI),and total liver perfusion(TLP) and image quality as image quality score,average CT value of abdomen aorta,signalto-noise ratio(SNR),carrier-to-noise ratio(CNR),and figure of merit(FOM) were compared used pair ttest or Mann-Whitney U-test between the two groups wherever appropriate.The effective radiation dose and iodine intake were also recorded and compared.Results The image quality and perfusion parameters had no significantly different between the two groups except for FOM.The effective radiation dose and iodine intake were 38.79％ and 27.03％ lower in the double low group.Conclusions Low concentration iso _osmolar contrast agent (iodixanol,270 mg/ml) together with low tube voltage (80 kV) helps to reduce radiation dose and iodine intake without compromising perfusion parameters and image quality in liver CT perfusion imaging.

Objective:To summarize the clinical experience of extracorporeal membrane oxygenation (ECMO) for neonatal refractory respiratory failure in a single medical center of Southwest China.Methods:From June 2020 to November 2021, the clinical data of neonates with refractory respiratory failure who received ECMO in the neonatal department of our hospital were retrospectively reviewed. The neonates were assigned into the survival group and the deceased group.Their general profile, clinical diagnosis, laboratory tests, ECMO operation, complications and prognosis were compared.Results:Eight neonates were included with five successfully withdrawal of ECMO and survived (5/8). For the three deceased neonates, two discontinued treatment because of intraventricular hemorrhage (grade Ⅲ~Ⅳ) and one confirmed congenital adrenal hyperplasia. No significant differences existed between the survival and the deceased groups in oxygenation index (OI), ECMO preparation and operation duration, usage of heparin, red blood cell suspension, platelet and sedative/analgesic drugs, therapeutic hypothermia and ECMO-associated complications. However, the deceased group had high OI values ( P=0.001), low lactate clearance ( P=0.005), more urine output during the first 24 h after ECMO ( P=0.046) and more fresh frozen plasma usage ( P=0.038). None of the five surviving children had significant developmental delay and neurological abnormalities during the 1-year follow-up. Conclusions:ECMO is effective treating neonatal refractory respiratory failure. Reducing the risk of intraventricular hemorrhage during ECMO may improve the survival rate.

Objective:To study the risk factors of bronchopulmonary dysplasia (BPD) in extremely preterm/extremely low birth weight infants(EPT/ELBWIs).Methods:From June 2019 to March 2022, clinical data of EPT/ELBWIs with gestational age <28 weeks or birth weight <1 000 g admitted to NICU of our hospital were retrospectively analyzed. They were assigned into BPD group and non-BPD group. Multivariate logistic regression analysis was used to find the independent risk factors for BPD and receiver operating characteristic (ROC) curve was used to determine the cut-off value for BPD. The incidences of BPD of the two groups were compared and the correlation between independent risk factors and BPD severity was analyzed.Results:A total of 82 EPT/ELBWIs were enrolled, including 47 (57.3%) in BPD group and 35 (42.7%) in non-BPD group. The BPD group had longer duration of both invasive and non-invasive mechanical ventilation (MV) [24.0(8.0, 38.0)d vs. 6.0 (0.2, 11.6)d, (38.4±14.5)d vs. (32.4±10.9)d], lower birth weight [906 (800, 970)g vs. 980 (880, 1 050)g],higher incidences of ureaplasma urealyticum colonization (48.9% vs. 22.9%) and hemodynamically significant patent ductus arteriosus (hsPDA) (76.6% vs. 51.4%) than the non-BPD group(all P<0.05). Multivariate logistic regression analysis showed that the independent risk factor for BPD was the duration of invasive MV ( OR=1.003, 95% CI 1.001-1.005). The cut-off value of invasive MV duration for predicting BPD was 14.4 d. The duration of invasive MV was positively correlated with BPD severity ( r=0.604, P<0.001). Conclusions:BPD is more likely to occur in EPT/ELBWIs with longer duration of invasive MV.