Transformation kinetics of exogenous nickel in a paddy soil during anoxic-oxic alteration: Roles of organic matter and iron oxides.

Nickel is generally released from flooded soils; however, the key Ni transformation processes in soils that are freshly contaminated by Ni2+ during anoxic-oxic alteration remain unclear. We developed a kinetic model to investigate the Ni transformation in paddy soils under anoxic and oxic conditions based on the results of the seven-step sequential extraction, determination of dissolved and soil organic matter, and surface site quantification, which provide the kinetic data of different Ni fractions, organic matter, and reactive sites for modeling. The dissolved, exchangeable, and specifically adsorbed Ni was gradually transferred to fulvic complex, humic complex, Fe-Mn oxide bound, and sulfide bound Ni after 40 d of anoxic incubation due to the increase in pH and soil surface sites, which were mainly induced by Fe(III) oxide reduction and soil organic matter release. The introduction of oxygen triggered a rapid release of Ni, which was ascribed to the decrease in pH and soil surface sites caused by Fe(II) oxidation and carbon re-immobilization. Kinetic modeling demonstrated that complexation with soil organic matter dominated Ni immobilization under anoxic conditions, while organic matter and Fe-Mn oxides contributed similarly to Ni release under oxic conditions, although the majority of Ni remained complexed with soil organic matter. These findings are important for the evaluation and prediction of Ni behavior in paddy soils with exogenous Ni during flooding-drainage practices.

Application of color-coded quantitative digital subtraction angiography in predicting the outcomes of immediate type I and type III endoleaks.

OBJECTIVE: Immediate type I and type III endoleaks after endovascular aneurysm repair (EVAR) could be persistent or temporary. Reintervention is necessary for persistent ones. Color-coded quantitative digital subtraction angiography (CQDSA) could provide a quantitative evaluation of the endoleak hemodynamics. We aimed to use CQDSA to quantify immediate type I and type III endoleaks after EVAR and to find a practical way to predict their outcomes. METHODS: Between January 2012 and December 2014, 485 consecutive patients with abdominal aortic aneurysms underwent EVAR at our institution. Thirty-five patients (31 men, four women) with slight immediate type I and type III endoleaks after EVAR were recruited in the prospective observational nested case-control study. After at least 6 months of follow-up, these patients were divided into two groups based on endoleak-related adverse events. Their final intraprocedure DSA images were collected and converted into a single polychromatic image for CQDSA measurements. The parameter time to peak (TTP) of the selected regions of interest in the endoleak area and a reference area at the same latitude within the stent graft were derived from the time-intensity curve. A receiver operating characteristic curve was generated to test the ability of TTP to predict endoleak-related adverse events and to identify the optimal cutoff value. RESULTS: Finally, two groups were identified: 12 patients with endoleak-related adverse events and 23 patients without endoleak-related adverse events. Median follow-up time for all patients was 24.0 months. Age, gender, and comorbidity were similar in these two groups. TTP was significantly lower in patients with endoleak-related adverse events (P = .002). The risk of endoleak-related adverse events was significantly higher in patients with mixed-type endoleak than in those with simple-type endoleak (P = .003). According to the receiver operating characteristic curves, TTP ≤5 seconds reached the maximal sum of sensitivity and specificity (sensitivity, 91.67%; specificity, 69.57%). Logistic regression analysis confirmed that TTP ≤5 seconds (P = .016) and mixed-type endoleak (P = .044) were associated with higher risk of endoleak-related adverse events. CONCLUSIONS: CQDSA could help predict the outcomes of immediate type I or type III endoleaks after EVAR. TTP ≤5 seconds and mixed-type endoleak were two potential predictors of endoleak-related adverse events. This approach may offer an objective assessment of such immediate endoleaks and reference for immediate reintervention or conservative therapy.

Flat-detector computed tomography PBV map in the evaluation of presurgical embolization for hypervascular brain tumors.

BACKGROUND: Preoperative embolization of hypervascular brain tumors is frequently used to minimize intraoperative bleeding. OBJECTIVE: To explore the efficacy of embolization using flat-detector CT (FDCT) parenchymal blood volume (PBV) maps before and after the intervention. MATERIALS AND METHODS: Twenty-five patients with hypervascular brain tumors prospectively received pre- and postprocedural FDCT PBV scans using a biplane system under a protocol approved by the institutional research ethics committee. Semiquantitative analysis, based on region of interest measurements of the pre- and post-embolization PBV maps, operating time, and blood loss, was performed to assess the feasibility of PBV maps in detecting the perfusion deficit and to evaluate the efficacy of embolization. RESULTS: Preoperative embolization was successful in 18 patients. The relative PBV decreased significantly from 3.98±1.41 before embolization to 2.10±2.00 after embolization. Seventeen patients underwent surgical removal of tumors 24 hours after embolization. The post-embolic tumor perfusion index correlated significantly with blood loss (ρ=0.55) and operating time (ρ=0.60). CONCLUSIONS: FDCT PBV mapping is a useful method for evaluating the perfusion of hypervascular brain tumors and the efficacy of embolization. It can be used as a supplement to CT perfusion, MRI, and DSA in the evaluation of tumor embolization.

Quantitative assessment of angiographic perfusion reduction using color-coded digital subtraction angiography during transarterial chemoembolization.

PURPOSE: The aim of this study was to develop a quantitative measurement of perfusion reduction using color-coded digital subtraction angiography (ccDSA) to monitor intra-procedural arterial stasis during TACE. MATERIALS AND METHODS: A total number of 35 patients with hepatocellular carcinoma who had undergone TACE were enrolled into the study. Pre- and post-two-dimensional digital subtraction angiography scans were conducted with same protocol and post-processed with ccDSA prototype software. Time-contrast-intensity (CI[t]) curve was obtained by region-of-interest (ROI) measurement on the generated ccDSA image. Quantitative 2D perfusion parameters time to peak, area under the curve (AUC), maximum upslope, and contrast intensity peak (CI-Peak) derived from the ROI-based CI[t] curve for pre- and post-TACE were evaluated to assess the reduction of antegrade blood flow and tumor blush. Relationships between 2D perfusion parameters, subjective angiographic chemoembolization endpoint (SACE) scale, and clinical outcomes were analyzed. RESULTS: Area normalized AUC and CI-Peak revealed significant reduction after the TACE (P < 0.0001). AUCnorm decreased from pre-procedure of 0.867 ± 0.242 to 0.421 ± 0.171 (P < 0.001) after completion of TACE. CI-Peaknorm was 0.739 ± 0.221 before TACE and 0.421 ± 0.174 (P < 0.001) after TACE. Tumor blood supply time slowed down obviously after embolization. A perfusion reduction either from AUCnorm or CI-Peaknorm ranging from 30% to 40% was associated with SACE level III and a reduction ranging from 60% to 70% was equivalent to SACE level IV. For intermediate reduction (SACE level III), better tumor response was found after TACE rather than a higher reduction (SACE level IV). CONCLUSION: ccDSA application provides an objective approach to quantify the perfusion reduction and subjectively evaluate the arterial stasis of antegrade blood flow and tumor blush caused by TACE.

Spontaneous Rupture of Hepatocellular Carcinoma Mimicking ST-Segment Elevation Myocardial Infarction.

BACKGROUND: Several medical conditions that mimic ST-elevation myocardial infarction (STEMI) have been reported previously, but acute abdominal disease mimicking STEMI is rare. CASE REPORT: We report on a 72-year-old man who presented to the emergency department (ED) with epigastric pain. Meanwhile, STEMI with shock developed. Anticoagulation medication and emergent percutaneous coronary intervention (PCI) were arranged in a timely manner. However, hepatocellular carcinoma (HCC) rupture was the true cause of the ST-segment elevation. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case report highlights the fact that acute myocardial infarction is not the only cause of ST-segment elevation. HCC rupture should be one of the differential diagnoses.