Search

Purpose: To investigate the imaging features indicating portal vein invasion (PVI) of hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced MRI and to create more accurate diagnostic criteria than the presence of portal vein tumor thrombosis (PVTT) on MRI. Methods: This retrospective study included patients with surgically resected HCC larger than 5 cm, and the presence of PVI was investigated. On MRI, we evaluated the image findings of portal vein occlusion, the parenchymal signal change caused by hemodynamic alterations of the portal vein, and their combination showing the highest odds ratio (OR) to define the diagnostic criteria for radiological PVI detection (rPVI criteria). The diagnostic performance and recurrence-free survival were compared between the rPVI criteria and the presence of PVTT using McNemar's test and Kaplan–Meier method, respectively. Interobserver agreement was evaluated using Cohen's weighted ĸ statistics. Results: Of 189 enrolled patients, 25 (13.2%) had PVI on histology. To diagnose PVI on MRI, either peripheral wedge-shaped arterial peritumoral hyperemia with an abrupt cut-off of a portal vein or the presence of PVTT had the highest OR (41.67, p < 0.001). The sensitivity of PVI was significantly increased under this diagnostic criterion (64.0% to 88.0%; p = 0.031) with comparable accuracy (95.2% vs. 94.7%; p > 0.999). In terms of recurrence-free survival, the patient group with rPVI was significantly worse (p = 0.017) compared with the patients without rPVI. Interobserver agreement of radiologic findings was substantial (ĸ = 0.64). Conclusion: Diagnostic criteria for radiologically PVI detection increase the sensitivity more than the only presence of PVTT. [ABSTRACT FROM AUTHOR]

Rationale and Objective: To evaluate the characteristic clinical and imaging findings of charcoal granuloma and suggest features that may differentiate charcoal granuloma from breast cancer. Materials and Methods: This retrospective study included 18 patients with a histologically confirmed breast charcoal granuloma between 2005 and 2021 at a single institution. All patients had a history of breast surgery after ultrasound (US)-guided charcoal marking. Two radiologists analyzed the radiologic findings of charcoal granulomas, including the presence of a mass or calcification; the shape, margin and density of the masses on mammography; and the location, size, shape, margin, orientation, echogenicity, vascularity, presence of an echogenic halo, and posterior acoustic shadowing on US. In cases with available follow-up images, we also investigated whether the size and shape had changed. Results: The median interval between breast surgery and the diagnosis of charcoal granuloma was 2.3 years (range, 0.7–18.3 years). Thirteen lesions (72.2%) were detected on screening images. In 11 (61.1%) cases, the surgical incision was not made in the tattooed skin area. Mammography showed positive findings in 10/15 patients, and most lesions were isodense masses (70%). There were no cases with calcification. On US, all lesions were masses and showed a taller-than-wide orientation (61.1%), round or oval shape (55.6%), and iso- or hyperechogenicity (83.3%). Echogenic halo (27.8%) and posterior acoustic shadowing (16.7%) were uncommon. On Doppler US, only four cases (22.2%) showed increased vascularity. Most were classified as BI-RADS 3 (38.9%) or 4A (50.0%). After biopsy, 12 patients had follow-up mammography and US. The size of the lesion decreased in nine cases and remained unchanged in three cases. A decrease in the lesion size after biopsy showed a negative correlation with the interval between detection on imaging and biopsy (p = 0.04). Conclusion: Charcoal granuloma is most commonly found 2–3 years after surgery and occurs more frequently when the incision site is different from the tattooed skin area. US findings of tall and round or oval masses with iso- or hyperechogenicity without increased vascularity could help to differentiate them from malignancies. [ABSTRACT FROM AUTHOR]

Indoor air quality, especially in terms of particulate matter (PM), is a critical public health concern. Although various methods for removing indoor PM have been suggested, the effects of various influential factors on PM deposition have not been clearly understood. Here, the effect of the flow structure inside a test chamber on PM deposition was quantitatively investigated using flow visualization techniques. To elucidate the flow parameters that influence the PM deposition, the efficiency of PM removal and deposition constant were examined for different flow directions, flow velocities, and distances between the fan and the surface of the test chamber. The spatial distributions of the mean velocity and turbulence intensity inside the test chamber were obtained experimentally using a particle image velocimetry technique to understand the mechanism associated with PM deposition. The overall mean velocity, recirculating flow region, and turbulent intensity in the near-wall regions may partially explain the difference in the PM deposition under various flow conditions. [ABSTRACT FROM AUTHOR]

The removal of radionuclides from the primary coolant system of nuclear power plants occurs with the dissolution of corrosion metal oxide layers deposited with the radionuclides. Kinetic dissolution experiments were conducted with a synthetic magnetite specimen in the form of a thin plate using an aqueous solution of oxalic acid as a reducing agent. The effects of acid concentration and temperature were investigated on the kinetics of the reductive dissolution of a magnetite specimen. In particular, the kinetic experiments were performed in a wide temperature range from low (57 °C) to high (120 °C), above the normal boiling point of water. The dissolution of magnetite increased with increasing acid concentration and temperature. The acid concentration dependence of the dissolution reaction rate of Fe at a given temperature was correlated with the nth power of the oxalic acid concentration. Additionally, the temperature dependence of the dissolution reaction rate of Fe at a fixed oxalic acid concentration was studied with an Arrhenius-type equation. [ABSTRACT FROM AUTHOR]

Recently, domestic gas turbines are primarily operated under partial loads. Hence, thermal expansion of components decreases, leading to a discontinuity between the 1st blade and 2nd vane. In this study, the local heat transfer coefficients are derived using the naphthalene sublimation method to analyze thermal characteristics based on step height, and flow characteristics are analyzed using numerical simulation. An extreme heat load of the flat endwall appears around the leading edge of the vane due to the secondary vortex. Under the step conditions, the heat load increases in the upstream region as the main flow near the endwall is reattached to the endwall surface. In addition, two high heat transfer distributions appear due to the recirculation flow, and a step-induced vortex is formed. As the step-induced vortex moves to the suction side within the vane flow path, a high thermal load appears in the corresponding region. Consequently, we found that the occurrence of a step causes severe thermal damage in the upstream region of the vane endwall. The area-averaged heat transfer of the stepped endwall is increased by about 10.6 % and 17.3 % at hs/Cx = 0.05 and 0.1, respectively, as compared to that of the flat endwall. [ABSTRACT FROM AUTHOR]

Chromium is a toxic and carcinogenic heavy metal that originates from various human activities. Therefore, the effective removal of chromium from aqueous solutions is an extremely important global challenge. Herein, we report a chitosan-coated iron oxide nanoparticle immobilized hydrophilic poly(vinylidene) fluoride membrane (Chi@Fe2O3–PVDF) which can potentially be used for efficient removal of hexavalent chromium(VI) by a simple filtration process. Membrane filtration is an easy and efficient method for treating large volumes of water in a short duration. The adsorption experiments were conducted by batch and continuous in-flow systems. The experimental data showed rapid capture of hexavalent chromium (Cr(VI)) which can be explained by the pseudo-second-order kinetic and Langmuir isotherm model. The nanocomposite membrane exhibited high adsorption capacity for Cr(VI) (14.451 mg/g in batch system, 14.104 mg/g in continuous in-flow system). Moreover, its removal efficiency was not changed significantly in the presence of several competing ions, i.e., Cl−, NO3−, SO42−, and PO43−. Consequently, the Chi@Fe2O3-PVDF-based filtration process is expected to show a promising direction and be developed as a practical method for wastewater treatment. [ABSTRACT FROM AUTHOR]