Towards a quantitative analysis of class activation mapping for deep learning-based computer-aided diagnosis

Class Activation Mapping (CAM) can be used to obtain a visual understanding of the predictions made by Convolutional Neural Networks (CNNs), facilitating qualitative insight into these neural networks when they are, for instance, used for the purpose of medical image analysis. In this paper, we investigate to what extent CAM also enables a quantitative understanding of CNN-based classification models through the creation of segmentation masks out of class activation maps, hereby targeting the use case of brain tumor classification. To that end, when a class activation map has been created for a correctly classified brain tumor, we additionally perform tumor segmentation by binarization of the aforementioned map, leveraging different methods for thresholding. In a next step, we compare this CAM-based segmentation mask to the segmentation ground truth, measuring similarity through the use of Intersection over Union (IoU). Our experimental results show that, although our CNN-based classification models have a similarly high accuracy between 86.0% and 90.8%, their generated masks are different. For example, our Modified VGG-16 model scores an mIoU of 12.2%, whereas AlexNet scores an mIoU of 2.1%. When comparing with the mIoU obtained by our U-Net-based models, which is between 66.6% and 67.3%, and where U-Net is a dedicated pixel-wise segmentation model, our experimental results point to a significant difference in terms of segmentation effectiveness. As such, the use of CAM for the purpose of proxy segmentation or as a ground truth segmentation mask generator comes with several limitations

mRNA vaccine effectiveness against SARS-CoV-2 B.1.617.2 (Delta) and B.1.1.529 (Omicron) variant transmission from home care cases to household contacts in South Korea

Objectives Household contacts of confirmed cases of coronavirus disease 2019 (COVID-19) are exposed to a high risk of viral transmission, and secondary incidence is an important indicator of community transmission. This study analyzed the secondary attack rate and mRNA vaccine effectiveness against transmission (VET) for index cases (patients treated at home) confirmed to be infected with the Delta and Omicron variants. Methods The subjects of the study were 4,450 index cases and 10,382 household contacts. Logistic regression analysis was performed to compare the secondary attack rate by vaccination status, and adjusted relative risk and 95% confidence intervals were identified. Results The secondary attack rate of the Delta variant was 27.3%, while the secondary attack rate of the Omicron variant was 29.8%. For the Delta variant, groups with less than 90 days and more than 90 days after 2 doses of mRNA vaccination both showed a VET of 37%. For the Omicron variant, a 64% VET was found among those with less than 90 days after 2 doses of mRNA vaccination. Conclusion This study provides useful data on the secondary attack rate and VET of mRNA vaccines for household contacts of COVID-19 cases in South Korea

Static and dynamic brain morphological changes in isolated REM sleep behavior disorder compared to normal aging

Objective/backgroundTo assess whether cerebral structural alterations in isolated rapid eye movement sleep behavior disorder (iRBD) are progressive and differ from those of normal aging and whether they are related to clinical symptoms.Patients/methodsIn a longitudinal study of 18 patients with iRBD (age, 66.1 ± 5.7 years; 13 males; follow-up, 1.6 ± 0.6 years) and 24 age-matched healthy controls (age, 67.0 ± 4.9 years; 12 males; follow-up, 2.0 ± 0.9 years), all participants underwent multiple extensive clinical examinations, neuropsychological tests, and magnetic resonance imaging at baseline and follow-up. Surface-based cortical reconstruction and automated subcortical structural segmentation were performed on T1-weighted images. We used mixed-effects models to examine the differences between the groups and the differences in anatomical changes over time.ResultsNone of the patients with iRBD demonstrated phenoconversion during the follow-up. Patients with iRBD had thinner cortices in the frontal, occipital, and temporal regions, and more caudate atrophy, compared to that in controls. In similar regions, group-by-age interaction analysis revealed that patients with iRBD demonstrated significantly slower decreases in cortical thickness and caudate volume with aging than that observed in controls. Patients with iRBD had lower scores on the Korean version of the Mini-Mental Status Examination (p = 0.037) and frontal and executive functions (p = 0.049) at baseline than those in controls; however, no significant group-by-age interaction was identified.ConclusionPatients with iRBD show brain atrophy in the regions that are overlapped with the areas that have been documented to be affected in early stages of Parkinson’s disease. Such atrophy in iRBD may not be progressive but may be slower than that in normal aging. Cognitive impairment in iRBD is not progressive

Safety and efficacy of Xiaoyao-san for the treatment of functional dyspepsia: a systematic review and meta-analysis of randomized controlled trials

Objective: Although Xiaoyao-san (XYS) is a popular herbal remedy for indigestion, there is insufficient evidence to recommend it as a treatment option for functional dyspepsia (FD). This review aimed to assess the safety and efficacy of XYS in patients with FD, compared to conventional Western medicine (WM).Methods: Two independent reviewers searched for randomized controlled trials (RCTs) using 11 electronic databases, including Medline and Embase, to evaluate therapeutic effects of XYS on FD up to 31 January 2023. The primary outcome was the total clinical efficacy rate (TCE), and secondary outcomes included scores of dyspepsia-related symptoms (DSS) and incidence of adverse events (AEs). The risk of bias was evaluated using the Cochrane collaboration tool, and data synthesis and subgroup analyses were performed using the Review Manager program.Results: Six studies involving 707 participants were included in the meta-analysis. XYS significantly improved TCE compared to WM (RR = 1.15, 95% CI: 1.05, 1.26, p = 0.002) with high heterogeneity (I2 = 59%, p = 0.06). Combination therapy also showed higher TCE than WM alone (RR = 1.22, 95% CI: 1.05, 1.41, p = 0.008), and the heterogeneity was low (I2 = 0%, p = 0.86). The results showed a greater reduction in DSS in the XYS and combination therapy groups than in the WM alone group (SMD = −0.72, 95% CI: −0.90, −0.53, p < 0.00001) with low heterogeneity (I2 = 44%, p = 0.15), especially for abdominal distension and upper abdominal pain. AEs occurred less frequently in the XYS and combination therapy groups than in the WM alone group (RR = 0.20, 95% CI: 0.07, 0.63, p = 0.006), and the heterogeneity was low (I2 = 45%, p = 0.18). The certainty of the evidence for each outcome was rated from “very low” to “high.”Conclusion: This review suggests that XYS is effective and safe for reducing complaints in patients with FD. However, high-quality RCTs should be conducted to establish more convincing therapeutic evidence of XYS for the treatment of FD.Systematic Review Registration:https://www.crd.york.ac.uk/prospero, CRD4202017884

Early countermeasures to COVID-19 at long-term care facilities in Gwangju Metropolitan City, Republic of Korea

Objectives The coronavirus disease 2019 (COVID-19) pandemic has continued since its first detection in the Republic of Korea on January 20, 2020. This study describes the early countermeasures used to minimize the risk of COVID-19 outbreaks during cohort quarantine and compares the epidemiological characteristics of 2 outbreaks in long-term care facilities (LTCFs) in Gwangju Metropolitan City in summer 2020. Methods An epidemiological investigation was conducted via direct visits. We investigated epidemiological characteristics, including incidence, morbidity, and mortality rates, for all residents and staff members. Demographic characteristics were analyzed using a statistical program. Additionally, the method of managing infection in LTCFs is described. Results Residents and caregivers had high incidence rates in LTCF-A and LTCF-B, respectively. LTCF-B had a longer quarantine period than LTCF-A. The attack rate was 20.02% in LTCF-A and 27.9% in LTCF-B. The mortality rate was 2.3% (1/43) in LTCF-B, the only facility in which a COVID-19 death occurred. Conclusion Extensive management requires contact minimization, which involves testing all contacts to mitigate further transmission in the early stages of LTCF outbreaks. The findings of this study can help inform and prepare public health authorities for COVID-19 outbreaks, particularly for early control in vulnerable facilities

The effectiveness of Paxlovid treatment in long-term care facilities in South Korea during the outbreak of the Omicron variant of SARS-CoV-2

Objectives On November 5, 2021, Pfizer Inc. announced Paxlovid (nirmatrelvir+ritonavir) as a treatment method that could reduce the risk of hospitalization or death for patients with confirmed coronavirus disease 2019 (COVID-19). Methods From February 6, 2022 to April 2, 2022, the incidence of COVID-19 and the effects of treatment with Paxlovid were analyzed in 2,241 patients and workers at 5 long-term care facilities during the outbreak of the Omicron variant of severe acute respiratory syndrome coronavirus 2 in South Korea. Results The rate of severe illness or death in the group given Paxlovid was 51% lower than that of the non-Paxlovid group (adjusted risk ratio [aRR], 0.49; 95% confidence interval [CI], 0.24−0.98). Compared to unvaccinated patients, patients who had completed 3 doses of the vaccine had a 71% reduced rate of severe illness or death (aRR, 0.29; 95% CI, 0.13−0.64) and a 65% reduced death rate (aRR, 0.35; 95% CI, 0.15−0.79). Conclusion Patients given Paxlovid showed a lower rate of severe illness or death and a lower fatality rate than those who did not receive Paxlovid. Patients who received 3 doses of the vaccine had a lower rate of severe illness or death and a lower fatality rate than the unvaccinated group

Welfare analysis of economic agents in distribution before and after FTA; imported grape, orange

This study examined and compared the effect of tariff reduction under Free Trade Agreements(FTAs) on the surplus of producers, consumers, and distributors, and on the change in price and marketing margin in a distribution channel, using an Equilibrium Displacement Model(EDM). As a result, consumer’s surplus is increased in imported grape and orange markets when the surplus is measured on a total volume basis, but consumer’s surplus is decreased in the imported grape market when the surplus is measured on a per unit basis. Also, an increase in marketing margins lead to increase price at retail level, although the import price is decreased by tariff reduction under FTA, which implies that tariff reduction or elimination does not leads to decrease price at retail level due to an increase in marketing margins. This suggests that most economic benefits from tariff reduction associated with imported agricultural products concentrated to marketing margins, and that establishing an efficient distribution system will be necessary in order to equally distribute the benefits of tariff reduction over various economic agents in a society

Association of the Use of a Heated Tobacco Product with Perceived Stress, Physical Activity, and Internet Use in Korean Adolescents: A 2018 National Survey

The awareness and use of the recently introduced heated product in the global tobacco market is rapidly increasing. Few studies have investigated the association of this product’s use with health-related factors. To examine the association of the heated tobacco product (HTP)’s use with perceived stress, physical activity, and internet use, we analyzed data from the Korea Youth Risk Behavior Survey using multinomial logistic regression models. The participants included 60,040 students from middle school and high school. There were significant associations between high perceived stress and cigarette use only, dual use of cigarette and e-cigarette, triple use of cigarette, e-cigarette, and HTP; a negative association between HTP’s use and perceived stress; positive association between physical activity and tobacco use; and not using the internet significantly increased the odds of use of all types of tobacco products. A smoking prevention program, tailored to meet the needs of different types of tobacco product users, is recommended. A program aimed at not only increasing awareness of perceived risk but also decreasing perceived benefits of risky behaviors, should also be considered. Further research using a longitudinal design to test the causal relationship of tobacco product use with perceived stress, physical activity, and internet use is warranted