Right ventricular end-systolic remodeling index on cardiac magnetic resonance imaging: comparison with other functional markers in patients with chronic thromboembolic pulmonary hypertension.

BACKGROUND: Cardiac magnetic resonance imaging (CMR) can provide important metrics of pulmonary hypertension. In the current study, we investigated whether the CMR-derived right ventricular end-systolic remodeling index (RVESRI) could be a metric in assessing the function and hemodynamics of chronic thromboembolic pulmonary hypertension (CTEPH). METHODS: A total of 64 patients (45±14 years, 37 males), including 46 patients with CTEPH and 18 patients with chronic pulmonary thromboembolism (CTE), were retrospectively enrolled. All patients underwent right heart catheterization and CMR within 7 days. RVESRI, right ventricular eccentricity index, right ventricular end-diastolic and end-systolic volume index, right ventricular ejection fraction, right ventricular cardiac output, and strain were analyzed on cine images of CMR. Hemodynamic parameters including mean pulmonary arterial pressure, pulmonary vascular resistance, and cardiac output were obtained from right heart catheterization. RESULTS: RVESRI of all patients was 1.50 (IQR, 1.26-1.90). Compared with CTE patients, RVESRI in patients with CTEPH was significantly increased (U=27.5, P<0.001). The interclass correlation coefficients of intra-observer reproducibility and inter-observer reproducibility for RVESRI measurement were 0.96 (95% CI, 0.93-0.97) and 0.99 (95% CI, 0.98-0.99), respectively. RVESRI positively correlated with right ventricular end-diastolic and end-systolic volume index and right ventricular global longitudinal strain (r=0.79, 0.83, 0.62, P<0.001), while it was negatively correlated with right ventricular ejection fraction (r=-0.64, P<0.001), right ventricular cardiac output (r=-0.50, P<0.001), and right ventricular eccentricity index (r=-0.81, P<0.001). RVESRI had a positive correlation with mean pulmonary arterial pressure (r=0.65, P<0.001) and pulmonary vascular resistance (r=0.69, P<0.001), while it was negatively correlated with cardiac output (r=-0.64, P<0.001). The receiver operating characteristic curve indicated that RVESRI >1.35 had a sensitivity of 97.8% and specificity of 83.3% in predicting mean pulmonary arterial pressure ≥25 mmHg, and its area under the curve (AUC) was 0.96±0.02. Meanwhile, the AUC of RVESRI was similar to RVEI (Z=1.635, P=0.102) and was more than the diameter of the main pulmonary artery (MPA) (Z=2.26, P=0.02) and the ratio of the MPA and ascending aorta diameter (MPA/AAo) (Z=3.826, P<0.001) in predicting mean pulmonary arterial pressure ≥25 mmHg. CONCLUSIONS: RVESRI measured on CMR is a simple and reproducible metric in assessing right ventricular function and hemodynamics in CTEPH patients.

Risk assessment of groundwater environmental contamination: a case study of a karst site for the construction of a fossil power plant.

This paper presents a demonstration of an integrated risk assessment and site investigation for groundwater contamination through a case study, in which the geologic and hydrogeological feature of the site and the blueprint of the fossil power plant (FPP) were closely analyzed. Predictions for groundwater contamination in case of accidents were performed by groundwater modeling system (GMS) and modular three-dimensional multispecies transport model (MT3DMS). Results indicate that the studied site area presents a semi-isolated hydrogeological unit with multiplicity in stratum lithology, the main aquifers at the site are consisted of the filled karst development layer with a thickness between 6.0 and 40.0 m. The poor permeability of the vadose zone at the FPP significantly restricted the infiltration of contaminants through the vadose zone to the subsurface. The limited influence of rarely isotropic porous karstified carbonate rocks on the groundwater flow system premised the simulate scenarios of plume migration. Analysis of the present groundwater chemistry manifested that that the groundwater at the site and the local area are of the HCO3-Ca, HCO3, and SO4-Ca types. A few of the water samples were contaminated by coliform bacteria and ammonia nitrogen as a result of the local cultivation. Prediction results indicate that the impact of normal construction and operation processes on the groundwater environment is negligible. However, groundwater may be partly contaminated within a certain period in the area of leakage from the diesel tanks, the industrial wastewater pool, and the cooling tower water tank in case of accidents. On a positive note, none of the plumes would reach the local sensitive areas for groundwater using. Finally, an anti-seepage scheme and a monitoring program are proposed to safeguard the groundwater protection. The integrated method of the site investigation and risk assessment used in this case study can facilitate the protection of groundwater for the construction of large-scale industrial project.

Assessment of site conditions for disposal of low- and intermediate-level radioactive wastes: a case study in southern China.

Near surface disposal of low- and intermediate-level radioactive wastes (LILW) requires evaluating the field conditions of the candidate site. However, assessment of the site conditions may be challenging due to the limited prior knowledge of some remote sites, and various multi-disciplinary data requirements at any given site. These situations arise in China as in the rest of the industrialized world, particularly since a regional strategy for LILW disposal has been implemented to protect humans and the environment. This paper presents a demonstration of the site assessment process through a case study focusing mainly on the geologic, hydrogeologic and geochemical characteristics of the candidate site. A joint on-site and laboratory investigation, supplemented by numerical modeling, was implemented in this assessment. Results indicate that no fault is present in the site area, although there are some minor joints and fractures, primarily showing a north-south trend. Most of the joints are filled with quartz deposits and would thus function hydraulically as impervious barriers. Investigation of local hydrologic boundaries has shown that the candidate site represents an essentially isolated hydrogeologic unit, and that little or no groundwater flow occurs across its boundaries on the north or east, or across the hilly areas to the south. Groundwater in the site area is recharged by precipitation and discharges primarily by evapo-transpiration and surface flow through a narrow outlet to the west. Groundwater flows slowly from the hilly area to the foot of the hills and discharges mainly into the inner brooks and marshes. Some groundwater circulates in deeper granite in a slower manner. The vadose zone in the site was investigated specially for their significant capability for restraining the transport of radionuclides. Results indicate that the vadose zone is up to 38m in thickness and is made up of alluvial clay soils and very highly weathered granite. The vadose zone has low saturated hydraulic conductivities on the order of 10(-5)cm/s and in this respect is well-suited for the disposal of LILW. The saturated formations are primarily made up of silt and moderately-to-slightly weathered granite, which exhibit even lower hydraulic conductivities, on the order of 10(-6)cm/s, also favorable for restraining the transport of radionuclides. Chemical analyses indicate that the groundwaters at the site are of the HCO(3)-Na · Ca and HCO(3) · SO(4)-Na · Ca types and are weakly corrosive to concrete and steel. Geochemical analyses indicate that the rock and soil materials (particularly weathered granite) at the site contain very small fractions of colloidal particles and exhibit low Cation Exchange Capacities (CEC), and would therefore have limited capacity for sorption of radionuclides. Groundwater flow and solute transport models of the candidate site have been developed using MODFLOW and MT3DMS, incorporating the data obtained during the assessment program. Calibration was based on the available measured groundwater level fluctuations and tracer concentrations from in situ dispersion tests. The longitudinal dispersion coefficient as determined in calibration is equal to 5.0 × 10(-3) m(2)/d. Numerical sensitivity analyses indicate that the hydraulic conductivity and the longitudinal dispersion coefficient are the key parameters controlling the transport of radionuclides, while the numerical model is not sensitive to changes in the effective porosity and the specific yield. Preliminary predictions have been performed with the calibrated model both for the natural setting of the site and the graded site in which the valleys of the site are backfilled with low permeable materials. Results indicate that the proposed site grading increases the safety of the site for disposal of LILW by reducing both the groundwater level and the hydraulic gradient and that radionuclide transport would not likely be a problem or cause groundwater contamination. Although there are some problems remaining to be addressed in future work, the conclusion of the assessment is that the conditions at this site are appropriate for LILW disposal. This study provides an example of the procedures necessary in an assessment of site conditions relevant to the safe disposal of LILW. Such an assessment is crucial to the site selection process and to subsequent environmental impact assessment.