RESUMO
The water conservation service function, which is one of the most important ecological service function in the regional system, directly reflects the regulation role of a region in precipitation, the redistribution function of precipitation, and the ecohydrological value. With the development of the comprehensive evaluation method and the deepening of research on water conservation service function, relevant evaluation calculation process has changed significantly. Nowadays, in the assessment of the water conservation service function, it is necessary not only to calculate and evaluate relevant indicators, but also to localize specific parameters in the model and analyze the effectiveness of the overall model for specific study areas. However, the current literature review lacks systematic summaries of model evaluation methods. Meanwhile, the review is also insufficient on model validity verification and significance analysis methods, the result verification and applicability analysis methods such as parameter localization in water conservation studies. We reviewed the research advance on typical ecosystem water conservation ser-vice assessment methods with a specific focus on the model assessment methods that have developed rapidly in recent years. At the same time, we summarized methods commonly used for parameter localization, as well as validity testing and sensitivity analysis of simulation results, and discussed existing problems and future directions in this field.
Assuntos
Conservação dos Recursos Hídricos , Ecossistema , Conservação dos Recursos Naturais , Previsões , ChinaRESUMO
The aim of the present study was to determine the correlation between dual-energy computed tomography (DECT) Hounsfield units (HU) and iron concentration, as well as the correlation between HU and magnetic resonance imaging (MRI)-derived R2* values, in phantoms of the heart and liver tissue. Phantoms were constructed containing pig heart or liver tissue and varying concentrations of iron (0.1, 5, 10, 15, 20 and 25 mg/ml). The phantoms were then examined by DECT and MRI. Linear regression analysis was used to determine the correlations between HU and iron concentration and HU and R2* values. The HU value of DECT increased with increasing iron concentrations in the liver and heart phantoms in a linear manner. The slope of the HU value change against iron concentration revealed that ΔH80-140 provided a better discernment of iron concentration as compared with ΔH100-140. The derived R2 values were all >0.9 for the associations of DECT and MRI measurements with iron concentrations. Therefore, DECT may be used for the determination of iron concentration in the liver and heart tissue, with the results correlating with those obtained with MRI.
RESUMO
OBJECTIVES: To investigate whether the addition of nitroglycerine to transcatheter arterial (chemo)embolization (TAE/TACE) can increase the delivery and effectiveness of TAE/TACE in patients with hepatocellular carcinoma (HCC) by dual-energy CT. METHODS: HCC patients (BCLC stage A or B) were randomized to (n = 51) or not to (n = 50) receive nitroglycerine and an emulsion of Lipiodol with or without doxorubicin, followed by embolization with Gelfoam pledgets. Dual-energy CT was performed pre- and 1 to 3 months post-embolization to assess changes in tumour diameter and Lipiodol levels in tumours. RESULTS: Median tumour diameter decreased from baseline in both groups with and without nitroglycerine (7.11 % vs. 12.5 %, respectively), and was statistically significant in the group receiving nitroglycerine (P = 0.023). There was no difference between the two groups in disease response (P = 0.237). The concentration and percentage of Lipiodol retained in tumours were significantly greater in patients treated with nitroglycerine compared to those without (median concentration 15.05 mg/mL vs. 4.40 mg/mL, respectively, P < 0.001; median percentage 82.01 % vs. 36.75 %, respectively, P < 0.001). CONCLUSIONS: Nitroglycerine increased delivery of the Lipiodol emulsion via TAE/TACE to HCC tumours with significant tumour reduction. Dual-energy CT can accurately quantify the amount of Lipiodol deposited in tumours. KEY POINTS: ⢠Nitroglycerine improves delivery of tumour-targeted therapy via enhanced permeability and retention. ⢠In hepatocellular carcinoma, nitroglycerine added to TAE/TACE showed greater tumour reduction. ⢠Dual-energy CT can reliably quantify the amount of Lipiodol in TAE/TACE.