Value of cardiopulmonary exercise testing in the assessment of symptoms and quality of life in Asian patients with chronic obstructive pulmonary disease.

Background: The natural course of chronic obstructive pulmonary disease (COPD) is characterized by symptom exacerbation and quality-of-life reduction. Therefore, symptoms should be properly assessed. Some studies have demonstrated a weak correlation between cardiopulmonary exercise testing (CPET) parameters and symptoms in patients with COPD; however, data on Asian patients are lacking. We investigated the value of CPET parameters in assessing symptoms and quality of life in Asian patients with COPD. Methods: Of 681 patients who underwent CPET at Asan Medical Center between January 2020 and June 2022, we analyzed 195 patients with COPD in this retrospective study. A cycle ergometer was used for the incremental protocol. The modified Medical Research Council (mMRC) dyspnea scale and COPD Assessment Test (CAT) were administered to assess the patients' symptoms. Results: The mMRC grade was related to maximal oxygen uptake (VO2 max, L/min) (Spearman's correlation coefficient ρ=-0.295, P<0.001) and physiological dead space/tidal volume ratio at peak exercise (VD/VT peak) (ρ=0.256, P<0.001). The CAT score was significantly correlated with VO2 max (L/min) (Spearman's correlation coefficient ρ=-0.297, P<0.001) and VD/VT peak (ρ=0.271, P<0.001), but had no correlation with breathing reserve (ρ=-0.122, P=0.089). The optimal cut-off values of VO2 max and VD/VT peak for predicting the onset of clinically significant dyspnea were 1.099 L/min and 0.295, respectively. Conclusions: VO2 max and VD/VT peak comprehensively reflect the symptoms and health-related quality of life of patients with COPD.

Noninvasive risk assessment of hepatic decompensation in patients with hepatitis B virus-related liver cirrhosis.

BACKGROUND AND AIM: Hepatic decompensation is a major complication of liver cirrhosis. We validated the predictive performance of the newly proposed CHESS-ALARM model to predict hepatic decompensation in patients with hepatitis B virus (HBV)-related cirrhosis and compared it with other transient elastography (TE)-based models such as liver stiffness-spleen size-to-platelet (LSPS), portal hypertension (PH), varices risk scores, albumin-bilirubin (ALBI), and albumin-bilirubin-fibrosis-4 (ALBI-FIB-4). METHODS: Four hundred eighty-two patients with HBV-related liver cirrhosis between 2006 and 2014 were recruited. Liver cirrhosis was clinically or morphologically defined. The predictive performance of the models was assessed using a time-dependent area under the curve (tAUC). RESULTS: During the study period, 48 patients (10.0%) developed hepatic decompensation (median 93 months). The 1-year predictive performance of the LSPS model (tAUC = 0.8405) was higher than those of the PH model (tAUC = 0.8255), ALBI-FIB-4 (tAUC = 0.8168), ALBI (tAUC = 0.8153), CHESS-ALARM (tAUC = 0.8090), and variceal risk score (tAUC = 0.7990). The 3-year predictive performance of the LSPS model (tAUC = 0.8673) was higher than those of the PH risk score (tAUC = 0.8670), CHESS-ALARM (tAUC = 0.8329), variceal risk score (tAUC = 0.8290), ALBI-FIB-4 (tAUC = 0.7730), and ALBI (tAUC = 0.7451). The 5-year predictive performance of the PH risk score (tAUC = 0.8521) was higher than those of the LSPS (tAUC = 0.8465), varices risk score (tAUC = 0.8261), CHESS-ALARM (tAUC = 0.7971), ALBI-FIB-4 (tAUC = 0.7743), and ALBI (tAUC = 0.7541). However, there was no significant difference in the predictive performance among all models at 1, 3, and 5 years (P > 0.05). CONCLUSIONS: The CHESS-ALARM score was able to reliably predict hepatic decompensation in patients with HBV-related liver cirrhosis and showed similar performance to the LSPS, PH, varices risk scores, ALBI, and ALBI-FIB-4.

How has COVID-19 impacted the economic resilience of retail clusters?: Examining the difference between neighborhood-level and district-level retail clusters.

The spread of COVID-19 greatly restricted physical and economic activities in global cities due to growing fears of infection and lockdown policies. Accordingly, the transfer of shopping activities from traditional markets to e-commerce has accelerated. Urban retail has substantially declined by competing with these disrupting factors, but resilience capabilities are known to vary by scale and regional characteristics. This study identifies which types of retail clusters were more resilient to the economic shock caused by the pandemic. This research focuses on the changes in online and in-store sales and how retailers recovered differently at the neighborhood and district levels in 2019 and 2020. This research compares the resilience of two types of retail clusters by calculating the loss of resilience and online adaptivity. The findings suggest that neighborhood-level retail areas were more resilient and bounced back in sales at a faster rate than district-level retail areas during the pandemic. These findings suggest that retail clusters are more resilient if they have steady populations and low-rent loads and can accommodate online shopping. The study contributes theoretical insights into how sales have changed and how e-commerce has increased the resilience of retail clusters throughout the pandemic by examining in-store and online sales.

New Method for Combined Quantitative Assessment of Air-Trapping and Emphysema on Chest Computed Tomography in Chronic Obstructive Pulmonary Disease: Comparison with Parametric Response Mapping.

OBJECTIVE: Emphysema and small-airway disease are the two major components of chronic obstructive pulmonary disease (COPD). We propose a novel method of quantitative computed tomography (CT) emphysema air-trapping composite (EAtC) mapping to assess each COPD component. We analyzed the potential use of this method for assessing lung function in patients with COPD. MATERIALS AND METHODS: A total of 584 patients with COPD underwent inspiration and expiration CTs. Using pairwise analysis of inspiration and expiration CTs with non-rigid registration, EAtC mapping classified lung parenchyma into three areas: Normal, functional air trapping (fAT), and emphysema (Emph). We defined fAT as the area with a density change of less than 60 Hounsfield units (HU) between inspiration and expiration CTs among areas with a density less than -856 HU on inspiration CT. The volume fraction of each area was compared with clinical parameters and pulmonary function tests (PFTs). The results were compared with those of parametric response mapping (PRM) analysis. RESULTS: The relative volumes of the EAtC classes differed according to the Global Initiative for Chronic Obstructive Lung Disease stages (p < 0.001). Each class showed moderate correlations with forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity (FVC) (r = -0.659-0.674, p < 0.001). Both fAT and Emph were significant predictors of FEV1 and FEV1/FVC (R² = 0.352 and 0.488, respectively; p < 0.001). fAT was a significant predictor of mean forced expiratory flow between 25% and 75% and residual volume/total vital capacity (R² = 0.264 and 0.233, respectively; p < 0.001), while Emph and age were significant predictors of carbon monoxide diffusing capacity (R² = 0.303; p < 0.001). fAT showed better correlations with PFTs than with small-airway disease on PRM. CONCLUSION: The proposed quantitative CT EAtC mapping provides comprehensive lung functional information on each disease component of COPD, which may serve as an imaging biomarker of lung function.

Risk assessment of hepatocellular carcinoma and liver-related events using ultrasonography and transient elastography in patients with chronic hepatitis B.

Cirrhosis has prognostic value. We investigated whether the combined use of ultrasonography (US) and transient elastography (TE) to diagnose cirrhosis is beneficial for the risk assessment of hepatocellular carcinoma (HCC) and liver-related events in patients with chronic hepatitis B (CHB). A total of 9300 patients with CHB who underwent US and TE in two institutions between 2006 and 2018 were enrolled. TE value ≥13 kPa was set to indicate cirrhosis. Patients were divided into four groups: US(+)TE(+) (cirrhosis by US and TE), US(+)TE(-) (cirrhosis by US, but not by TE), US(-)TE(+) (cirrhosis by TE, but not by US) and US(-)TE(-) (non-cirrhosis by US and TE).The patients were predominantly male (n = 5474, 58.9%) with a mean age of 47.5 years. The proportions of patients with cirrhosis diagnosed by US and TE were 17.2% (n = 1595) and 13.2% (n = 1225), respectively. The proportion of patients with discordant results in diagnosing cirrhosis by US and TE was 18.7% (n = 1740). During follow-up (median: 60.0 months), HCC and liver-related events developed in 481 (5.2%) and 759 (8.2%) patients, respectively. The cumulative incidence rates of HCC and liver-related events were highest in the US(+)TE(+) group, intermediate-high in the US(-)TE(+) group, intermediate-low in the US(+)TE(-) group and lowest in the US(-)TE(-) group (overall p < .001). Cirrhosis assessed using US and TE was a major predictor of HCC and liver-related event development in patients with CHB. Cirrhosis assessed using TE seemed better in predicting HCC or liver-related events than using US, when cirrhosis diagnosis was discordant by US and TE.

Assessment Of Changes In Regional Xenon-Ventilation, Perfusion, And Ventilation-Perfusion Mismatch Using Dual-Energy Computed Tomography After Pharmacological Treatment In Patients With Chronic Obstructive Pulmonary Disease: Visual And Quantitative Analysis.

Purpose: To assess changes in regional ventilation (V), perfusion (Q), and V-Q mismatch in patients with chronic obstructive pulmonary disease (COPD) after pharmacologic treatment using combined xenon-enhanced V and iodine-enhanced Q dual-energy CT (DECT). Patients and methods: Combined V and Q DECT were performed at baseline and after three-month pharmacologic treatment in 52 COPD patients. Anatomically co-registered virtual non-contrast images, V, Q, and V/Qratio maps were obtained. V/Q pattern was visually determined to be matched, mismatched, or reversed-mismatched and compared with the regional parenchymal disease patterns of each segment. DECT parameters for V, Q, and V-Q imbalance were quantified. Results: The parenchymal patterns on CT were not changed at follow-up. The segments with matched V/Q pattern were increased (80.2% to 83.6%) as the segments with reversed-mismatched V/Q pattern were decreased with improving ventilation (17.6% to 13.8%) after treatment. Changes of V/Q patterns were mostly observed in segments with bronchial wall thickening. Compared with patients without bronchial wall thickening, the quantified DECT parameters of V-Q imbalance were significantly improved in patients with bronchial wall thickening (p < 0.05). Changes in forced expiratory volume in one second after treatment were correlated with changes in the quantified DECT parameters (r = 0.327-0.342 or r = -0.406 and -0.303; p < 0.05). Conclusion: DECT analysis showed that the V-Q imbalance was improved after the pharmacological treatment in COPD patients, although the parenchymal disease patterns remained unchanged. This improvement of V-Q imbalance may occur mostly in the areas with bronchial wall thickening.

Assessment of frequency drift on CEST MRI and dynamic correction: application to gagCEST at 7 T.

PURPOSE: To investigate the effect of a frequency drift of the static magnetic field on 3D CEST MRI based on glycosaminoglycans (GAGs) of articular cartilage at 7 T and to introduce a retrospective correction method that uses the phase images of the gradient-echo readout. METHODS: Repeated gagCEST and B0 measurements were performed in a glucose model solution and in vivo in the knee joint of 3 healthy volunteers at 7 T. Phase images of the modified 3D rectangular spiral centric-reordered gradient-echo CEST sequence were used to quantify and compensate the apparent frequency drift in repeated gagCEST measurements. RESULTS: The frequency drift of the MRI scanner strongly influences the gagCEST signal in the articular cartilage of the human knee joint. The gagCEST signal in the articular cartilage is changed by 0.18%/Hz while an average drift of 0.7 ± 0.2 Hz/minute was observed. The proposed correction method can be applied retrospectively without the need of additional measurements and provides improved comparability and reproducibility for gagCEST studies. This correction method may also be of interest for other applications of CEST MRI. CONCLUSION: Prospective or retrospective correction of the frequency drift of the MRI scanner is essential for reproducible gagCEST measurements. The proposed retrospective correction method fulfills this requirement without the need of additional measurements.

Quantitative assessment of pulmonary vascular alterations in chronic obstructive lung disease: Associations with pulmonary function test and survival in the KOLD cohort.

PURPOSE: Despite the high prevalence of pulmonary vascular alterations and their substantial impact on chronic obstructive pulmonary disease (COPD), tools for the direct in vivo assessment of pulmonary vascular alterations remain limited. Thus, the purpose of this study was to automatically extract pulmonary vessels from volumetric chest CT and evaluate the associations between the derived quantitative pulmonary vessel features and clinical parameters, including survival, in COPD patients. METHODS: This study included 344 adult COPD patients. Pulmonary vessels were automatically extracted from volumetric chest CT data. Quantitative pulmonary vessel features were obtained from various lung surface areas (LSAs), which are theoretical surface areas drawn at different depths from the pleural borders. The total number of vessels (Ntotal) and number of vessels with vessel area (VA) less than 5 mm2 (N<5mm) were counted as both robust values and as values per 10 cm2 of LSA (Ntotal/LSA; N<5mm/LSA). The average VA (VAmean) and percentage of measured VA in the corresponding LSA (%VA) were measured. Associations between quantitative pulmonary vessel features and clinical parameters, including survival and the pulmonary function test (PFT), were evaluated. RESULTS: The pulmonary vessels were automatically extracted with 100% technical success. Cox regression analysis showed Ntotal/LSA, N<5mm/LSA, VAmean, and %VA to be significant predictors of survival (hazard ratio (HR), 0.80, 0.75, 0.70, 0.49, respectively). Patients classified into high-risk groups by %VA18mm (cut-off = 3.258), chosen because it demonstrated the strongest statistical influence on survival in a univariate Cox analysis, were associated with worse overall survival before (HR, 4.83; p < 0.001) and after adjustment for patient age and BMI (HR, 2.18; p = 0.014). Of the quantitative pulmonary vessel features, Ntotal/LSA, N<5mm/LSA, and %VA were correlated with FEV1, FEV1/FVC, and DLCO in all LSAs. The strongest correlation with PFTs was noted at LSA9mm for both Ntotal (FEV1, r = 0.33; FEV1/FVC, r = 0.51) and N<5mm (FEV1, r = 0.35; FEV1/FVC, r = 0.52). For %VA, the association was most evident at LSA18mm (FEV1, r = 0.27; FEV1/FVC, r = 0.47). Significant moderate to strong correlations were consistently observed between the extent of emphysema and quantitative pulmonary vessel features (r = 0.44-0.66; all p < 0.001). CONCLUSIONS: The automated extraction of pulmonary vessels and their quantitative assessment are technically feasible. Various quantitative pulmonary vessel features demonstrated significant relationships with survival and PFT in COPD patients. Of the various quantitative features, the percentage of total VA measured at 18 mm depth from the pleural surface (%VA18mm) and the number of small vessels counted per 10 cm2 of LSA at 9 mm depth from the pleural surface (N<5mm/LSA9mm) had the strongest predictability for the clinical parameters.

Assessment of regional emphysema, air-trapping and Xenon-ventilation using dual-energy computed tomography in chronic obstructive pulmonary disease patients.

OBJECTIVES: To compare the parenchymal attenuation change between inspiration/expiration CTs with dynamic ventilation change between xenon wash-in (WI) inspiration and wash-out (WO) expiration CTs. METHODS: 52 prospectively enrolled COPD patients underwent xenon ventilation dual-energy CT during WI and WO periods and pulmonary function tests (PFTs). The parenchymal attenuation parameters (emphysema index (EI), gas-trapping index (GTI) and air-trapping index (ATI)) and xenon ventilation parameters (xenon in WI (Xe-WI), xenon in WO (Xe-WO) and xenon dynamic (Xe-Dyna)) of whole lung and three divided areas (emphysema, hyperinflation and normal) were calculated on virtual non-contrast images and ventilation images. Pearson correlation, linear regression analysis and one-way ANOVA were performed. RESULTS: EI, GTI and ATI showed a significant correlation with Xe-WI, Xe-WO and Xe-Dyna (EI R = -.744, -.562, -.737; GTI R = -.621, -.442, -.629; ATI R = -.600, -.421, -.610, respectively, p < 0.01). All CT parameters showed significant correlation with PFTs except forced vital capacity (FVC). There was a significant difference in GTI, ATI and Xe-Dyna in each lung area (p < 0.01). CONCLUSIONS: The parenchymal attenuation change between inspiration/expiration CTs and xenon dynamic change between xenon WI- and WO-CTs correlate significantly. There are alterations in the dynamics of xenon ventilation between areas of emphysema. KEY POINTS: • The xenon ventilation change correlates with the parenchymal attenuation change. • The xenon ventilation change shows the difference between three lung areas. • The combination of attenuation and xenon can predict more accurate PFTs.

Assessment of Regional Xenon Ventilation, Perfusion, and Ventilation-Perfusion Mismatch Using Dual-Energy Computed Tomography in Chronic Obstructive Pulmonary Disease Patients.

OBJECTIVES: The aim of this study was to assess the feasibility of combined xenon-enhanced ventilation (V) and iodine-enhanced perfusion (Q) dual-energy computed tomography (DECT) to evaluate regional V and Q status in patients with chronic obstructive pulmonary disease (COPD). MATERIALS AND METHODS: Combined V and Q DECT imaging was performed in 52 prospectively enrolled male COPD patients. Virtual noncontrast images, V maps, and Q maps were anatomically coregistered with deformable registration and evaluated using in-house software. After normalization of the V and Q values of each pixel, normalized V and Q, V/Qratio, and VQmin (ie, the smaller of the V and Q in each pixel) maps were generated. For visual analysis, the V/Qratio pattern was determined to be matched, mismatched, or reversed mismatched and compared with the regional disease patterns--emphysema with/without bronchial wall thickening, bronchial wall thickening, or normal parenchyma--in each segment. The mean V, Q, V/Qratio, and VQmin values and the standard deviation of the V/Qratio (V/QSD) of each patient were quantified and compared with pulmonary function test (PFT) parameters using the Pearson correlation test. RESULTS: Segments with normal parenchyma showed a matched V/Qratio pattern, whereas segments with bronchial wall thickening commonly showed a reversed mismatched V/Qratio pattern. In the emphysema areas, the matched, mismatched, and reversed mismatched patterns were mixed without a dominant pattern. In quantitative analysis, the mean V, Q, VQmin, and V/Qratio values were significantly and positively correlated with PFT parameters (r = 0.290-0.819; P < 0.05). The V/QSD was significantly and negatively correlated with PFT parameters (r = -0.439 to -0.736; P < 0.001). VQmin values showed the best correlation with PFT parameters (r = 0.483-0.819; P < 0.001). CONCLUSIONS: Visual and quantitative assessment of the regional V, Q, V/Qratio, and VQmin is feasible with combined V and Q DECT imaging and significantly correlate with PFT results in COPD patients. Assessing disease patterns using conventional computed tomography images may not provide correct evaluation of regional V and Q in COPD patients with emphysema.

Solvent-free synthesis of Cu2ZnSnS4 nanocrystals: a facile, green, up-scalable route for low cost photovoltaic cells.

Efficient Cu2ZnSnSe4 (CZTSe) solar cells were fabricated with a simple, environmentally friendly, and scalable synthetic method for Cu2ZnSnS4 (CZTS) nanocrystals. CZTS nanoparticles were mechanochemically synthesized from elemental precursors on a relatively large scale (∼20 g), during which no solvents or additives were used, thus alleviating the complex process of particle synthesis. An analysis of the time evolution of the crystalline phase and morphology of precursor powders revealed that the formation of the CZTS compound was completed in 0.5 h once initiated, suggesting that the mechanochemically induced self-propagating reaction prevails. CZTS ink was prepared by dispersing the as-synthesized nanoparticles in an environmentally benign solvent (160 mg mL(-1) in ethanol) without using any additives, after which it was cast onto Mo-coated glass substrates by a doctor-blade method. Subsequent reactive annealing at 560 °C under a Se-containing atmosphere resulted in substantial grain growth along with the nearly complete substitution of Se. The CZTSe solar cells therefrom exhibited power conversion efficiency levels as high as 6.1% (based on the active area, 0.44 cm(2)) with a relatively high open-circuit voltage (0.42 V) in comparison with the bandgap energy of 1.0 eV.