Predictive model of pheochromocytoma based on the imaging features of the adrenal tumours

The purpose of our study was to develop a predictive model to rule out pheochromocytoma among adrenal tumours, based on unenhanced computed tomography (CT) and/or magnetic resonance imaging (MRI) features. We performed a retrospective multicentre study of 1131 patients presenting with adrenal lesions including 163 subjects with histological confirmation of pheochromocytoma (PHEO), and 968 patients showing no clinical suspicion of pheochromocytoma in whom plasma and/or urinary metanephrines and/or catecholamines were within reference ranges (non-PHEO). We found that tumour size was significantly larger in PHEO than non-PHEO lesions (44.3 +/- 33.2 versus 20.6 +/- 9.2 mm respectively; P < 0.001). Mean unenhanced CT attenuation was higher in PHEO (52.4 +/- 43.1 versus 4.7 +/- 17.9HU; P < 0.001). High lipid content in CT was more frequent among non-PHEO (83.6% versus 3.8% respectively; P < 0.001); and this feature alone had 83.6% sensitivity and 96.2% specificity to rule out pheochromocytoma with an area under the receiver operating characteristics curve (AUC-ROC) of 0.899. The combination of high lipid content and tumour size improved the diagnostic accuracy (AUC-ROC 0.961, sensitivity 88.1% and specificity 92.3%). The probability of having a pheochromocytoma was 0.1% for adrenal lesions smaller than 20 mm showing high lipid content in CT. Ninety percent of non-PHEO presented loss of signal in the out of phase MRI sequence compared to 39.0% of PHEO (P < 0.001), but the specificity of this feature for the diagnosis of non-PHEO lesions low. In conclusion, our study suggests that sparing biochemical screening for pheochromocytoma might be reasonable in patients with adrenal lesions smaller than 20 mm showing high lipid content in the CT scan, if there are no typical signs and symptoms of pheochromocytoma

CO2 sensing properties of WO3 powder: experimental and theoretical studies

Tungsten oxide (WO3) powders were obtained in this work by both wet chemical synthesis and homogeneous precipitation with ultrasound-assisted radiation methods. Experimental and theoretical investigations were performed to study the effect of the synthesis method and molarity concentration on the structural, optical, electric, and gas sensing properties of WO3. X-ray powder diffraction and Raman spectroscopy confirmed the presence of the monoclinic γ-phase. Rietveld refinement and size/strain calculations were done to perform a complete powder diffraction data analysis. The bandgap was calculated based on UV–Visible Diffuse Reflectance Spectroscopy data, resulting in 2.55 and 2.58 eV for the prepared samples by wet chemical and homogeneous precipitation methods, respectively. These experimental measurements were explained by first-principles total energy calculations, and the structural and electric properties of WO3 (002) surface were determined. Five atomic models were built with the purpose of determining the most stable structure of this surface with different oxygen terminations. Sensing tests were carried out for all the WO3 samples when interacting with carbon dioxide (CO2) molecules to analyze their performance as gas detecting devices. Parameters such as the sensing response, surface resistance behavior and response/recovery times were investigated in detail. Experimental tests confirmed that the maximum sensing response is obtained at 500 ppm of CO2, when operated at 300 °C. Based on the characterizations and gas sensing results, a CO2 gas sensing mechanism of WO3 was proposed and discussed in this work. Finally, the competitive properties of WO3 as a semiconductor-based gas sensor for CO2 detection were confirmed.Fil: Lozano Rosas, R.. Benemérita Universidad Autónoma de Puebla; MéxicoFil: Lamas, Diego Germán. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Tecnologías Emergentes y Ciencias Aplicadas. - Universidad Nacional de San Martin. Instituto de Tecnologías Emergentes y Ciencias Aplicadas; ArgentinaFil: Sánchez Ochoa, Francisco. Universidad Nacional Autónoma de México; MéxicoFil: Cocoletzi, Gregorio H.. Benemérita Universidad Autónoma de Puebla; MéxicoFil: Karthik, T. V. K.. Universidad Autónoma del Estado de Hidalgo; MéxicoFil: Robles Águila, M.J.. Benemérita Universidad Autónoma de Puebla; Méxic