Optimizing lung biopsy procedures:Comparative analysis of diagnostic efficacy and safety in experimental low-dose, conventional low-dose, and standard-dose CT-guided approaches.

PURPOSE: Lung cancer is a major cause of cancer-related deaths, emphasizing the importance of early diagnosis. CT-guided percutaneous lung biopsy(CT-PLB) is a valuable method for diagnosing lung lesions, but multiple scans can elevate radiation exposure. This study aims to compare diagnostic efficacy and safety across different CT-PLB protocols. METHODS: 273 consecutive patients who underwent CT-PLB between June 2018 and February 2021 were enrolled, and were divided into standard-dose, conventional low-dose, and experimental low-dose groups. The study mainly evaluated technical success, diagnostic efficacy, radiation dose, complications, and image quality. RESULTS: 93 patients were assigned to standard-dose group, 85 to conventional low-dose group, and 95 to experimental low-dose group. Technical success rates in these groups were 97.9%, 100%, and 97.9%, respectively. Procedure-related complications rates were similar across the groups(pneumothorax:p=0.71, hemorrhage:p=0.59). Sensitivity, specificity, and overall diagnostic accuracy were comparable among three groups(p=0.59,1.0,0.65), with respective values of 90.5%, 100%, and 93.2% in standard-dose group, 88.1%, 100%, and 90.5% in conventional low-dose group, and 91.9%, 100%, and 93.4% in experimental low-dose group. The effective dose (ED) in the experimental low-dose group was significantly lower compared to both the standard-dose and conventional low-dose CT-PLB groups[ED: 1.49(1.0∼1.97) mSv vs 5.42(3.92∼6.91) mSv vs 3.15(2.52∼4.22) mSv, p<0.001]. CONCLUSIONS: This study has developed a standardized six-step procedure for CT-PLB using experimental low-dose settings. It can achieve comparable diagnostic efficacy to conventional low-dose and standard-dose CT-PLB protocols while substantially reducing radiation exposure. These findings indicate that the experimental low-dose protocol could serve as a safe and effective alternative for CT-PLB.

In Situ Reactor-Integrated Electrospray Ionization Mass Spectrometry for Heterogeneous Catalytic Reactions and Its Application in the Process Analysis of High-Pressure Liquid-Phase Lignin Depolymerization.

Process analysis of heterogeneous catalytic reactions such as lignin depolymerization is essential to understand the reaction mechanism at the molecular level, but it is always challenging due to harsh conditions. Herein, we report an operando process analysis strategy by combining a microbatch reactor with high-resolution mass spectrometry (MS) via a reactor-integrated electrospray ionization (R-ESI) technique. R-ESI-MS expands the applications of traditional in situ MS to a heterogeneous and high-pressure liquid-phase system. With this strategy, we present the evolution of a series of monomers, dimers, and oligomers during lignin depolymerization under operando conditions (methanol solvent, 260 °C, ∼8 MPa), which is the first experimental elucidation of a progressive depolymerization pathway and evidence of repolymerization of active monomers. The proposed R-ESI-MS is crucial in probing depolymerization intermediates of lignin; it also provides a flexible strategy for process analysis of heterogeneous catalytic reactions under operando conditions.

Evidence of a Phenolic Pool as a Key Intermediate for Zeolite-Catalyzed Lignin Pyrolysis.

The phenolic pool is considered to be an important intermediate during the catalytic conversion of biomass. However, no direct evidence has been reported on its full picture on a molecular level due to the huge challenges in probing the reactive and lowly volatile phenolic oligomers with state-of-the-art technologies. Herein, we report the online detection and structural identification of a phenolic pool by utilizing in-situ atmospheric-pressure photoionization mass spectrometry, demonstrating that the phenolic pool is formed through repolymerization of monomers with an equidistant group pattern and acts as a key mechanistic step for both valuable aromatic products and undesired coke. The exploration of the real reactive species is also of great importance for the rational design and synthesis of advanced catalysts with high activity.

In Situ Atmospheric Pressure Photoionization Mass Spectrometric Monitoring of Initial Pyrolysis Products of Biomass in Real Time.

Knowledge on the initial and intermediate pyrolysis products of biomass is essential for the mechanistic investigation of biomass pyrolysis and further optimization of upgrading processes. The conventional method can only detect the final products, which do not resemble the initial or intermediate pyrolysis products. Here, we introduce a direct orifice sampling combined with atmospheric pressure photoionization mass spectrometry (APPI-MS) for in situ online analysis of the evolved volatile initial products from the pyrolysis of biomass. Pyrolysis experiments of both dimeric model compound (guaiacylglycerol-ß-guaiacyl ether, GGGE) and poplar wood were carried out to validate the generality of the method. Generally, secondary reactions can be reduced by shortening the distance between the sample and sampling orifice. Large molecular-weight initial products up to trimers were detected during the pyrolysis of poplar wood, and no initial products larger than trimers were detected. It is inferred that in situ APPI immediately after sample extraction ensures efficient and effective product detection. Furthermore, the present work offers a promising feasible method for online tracing of reaction intermediates not only in pyrolysis but also in various reactive processes (e.g., catalytic reaction, oxidation) under operando conditions.

Online photoionization mass spectrometric evaluation of catalytic co-pyrolysis of cellulose and polyethylene over HZSM-5.

The hydrogen-deficient and oxygen-rich nature of lignocellulosic biomass prohibits effective conversions of biomass to fuels and chemicals via catalytic pyrolysis due to significant coking of the catalysts. Co-feeding of biomass feedstock with hydrogen-rich and oxygen-deficient thermoplastics could improve the process. Herein, thermal and catalytic co-pyrolysis of cellulose and polyethylene (PE) was studied via thermogravimetry combined with an online photoionization time-of-flight mass spectrometry (PI-TOF-MS). No notable synergetic effect was found in the thermal co-pyrolysis process while a considerable synergetic effect was observed during the catalytic co-pyrolysis. In the case of catalytic pyrolysis, co-feeding of cellulose with PE significantly improved the aromatic formation. Detailed reaction intermediates and products were detected by PI-TOF-MS and the process of aromatization could be ascribed to aromatization of small oxygenates and olefins, as well as Diels-Alder reaction and dehydration by HZSM-5. Moreover, this study provides a reliable tool for screening and optimizing of catalytic co-pyrolysis.