CT of Post-Acute Lung Complications of COVID-19

Factors associated with phenotypes of dyspnea in post-COVID-19 condition: a cross-sectional study

Post-COVID-19 condition (PCC) is defined as the persistence of symptoms, like fatigue and dyspnea, at least 3 months post-COVID infection. As dyspnea is a common symptom, we attempted to further clinically phenotype those with PCC-associated dyspnea. 1642 adults (average age of 49.6y with 63% female-predominance and BMI of 31.2 kg/m2) with physician confirmed diagnosis of PCC from June 2020-April 2023 in Alberta, Canada were included. Those with dyspnea were more likely to be female (56.5%, p = 0.005) and have higher BMI (31.3 kg/m2 vs. 29.5 kg/m2; p = 0.0008), history of asthma (21.1% vs. 12.3%; p < 0.001), more persistent PCC symptoms (p = 0.0001), more functional limitations, as well as lower quality of life (p < 0.0001). Multivariable-adjusted logistic regression analysis demonstrated dyspnea was independently associated with fatigue (OR = 4.20; CI = 2.71,6.59) and inversely associated with hospitalization for COVID-19 (OR = 0.53; CI = 0.32,0.91), age (OR = 0.98 per one year of age; CI = 0.96,0.99) and 6-min-walk-distance per 10 m difference (OR = 0.98, CI = 0.96,1.0). Fatigue was a predictor of dyspnea, and was associated with milder infection, higher BMI, and reduced 6-min-walk-distance despite normal pulmonary function. Reduced TLC or DLCO was associated with more severe infection and reduced 6-min-walk-distance. Thus, we speculate there are at least two dyspnea-associated phenotypes: phenotype with pronounced fatigue (normal PFT) and phenotype with pronounced pulmonary abnormalities (abnormal PFT). Improved understanding of the dyspnea-associated phenotypes may allow for better targeted rehabilitation.

[Correlation between comorbidities and thoracic CT manifestations of COVID-19 pneumonia]

BACKGROUND AND OBJECTIVES

Pulmonary manifestation of coronavirus disease 2019 (COVID-19) is described using standardized computed tomography (CT) morphologic criteria. In this study, we investigated possible associations between thoracic CT manifestations in COVID-19 pneumonia and typical comorbidities, as well as clinical course.

METHODS

We analyzed clinical data and pulmonary imaging of 61 patients with positive PCR test. Pulmonary changes were categorized and reviewed for associations with pre-existing comorbidities and clinical course.

RESULTS

Compared to patients with atypical infiltrate patterns (2/19, 10.5%), 25 patients with typical infiltrate patterns (25/42, 59.5%) were significantly more likely to receive intensive care (p<0.001). In addition, patients with typical infiltrate patterns were more likely to receive non-invasive ventilation (12/42, 28.6%, p=0.040) and high-flow therapy (8/42, 19%, p=0.041) compared to patients with atypical infiltrate patterns. Mortality was also higher in patients with typical infiltrate patterns, with 15 patients (15/42, 35.7%) dying during follow-up compared to only 1 patient with atypical infiltrate pattern (1/19, 10.5%, p=0.012). No significant association between specific comorbidities and the resulting infiltrate pattern could be demonstrated.

CONCLUSIONS

Patients with a typical COVID-19 infiltrate pattern are more likely to receive intensive care and show higher mortality rates. Further analysis with larger patient collectives is needed to identify specific risk factors for typical COVID-19 pneumonia.

Clinical phenotype and outcome of persistent SARS-CoV-2 replication in immunocompromised hosts: a retrospective observational study in the Omicron era

PURPOSE

This study aims to describe clinical, virological and radiological characteristics as well as treatment strategies and outcomes of immunocompromised patients with persistent SARS-CoV-2 replication.

METHODS

We performed a retrospective cohort study of immunocompromised patients at the University Medical Center Freiburg between 01/2022 and 05/2023. Patients with substantial immunosuppression and persistent SARS-CoV-2 detection (Ct-value < 30 after 14 days) were included.

RESULTS

36 patients in our cohort reported mainly fever, dyspnoea or continuous cough. Viral load was significantly higher in concurrent samples taken from the lower respiratory tract (Ct-value = 26) than from the upper respiratory tract (Ct-value = 34). Time of detectable viral RNA after start of antiviral treatment was shorter in patients receiving two antivirals (median 15 days vs. 31 days with one antiviral agent). Short-course antiviral therapy (≤ 5 days) was less efficient in reduction of symptoms and viral load than prolonged therapy > 10 days. In 30% (8/27) of patients with repeated CT scans, we found the emergence of chronic pulmonary changes, which were more frequently in patients with B cell depletion (37%, 7/19) compared to patients with organ transplantation (12%, 2/17).

CONCLUSION

Ongoing SARS-CoV-2 replication in the lower respiratory tract is a relevant differential diagnosis in patients with severe immunosuppression and continuous cough, fever or dyspnoea even if nasopharyngeal swabs test negative for SARS-CoV-2. Especially in B cell-depleted patients, this may lead to inflammatory or fibrotic-like pulmonary changes, which are partially reversible after inhibition of viral replication. Antiviral therapy seems to be most effective in combination and over a prolonged period of time of > 10 days.

TRIAL REGISTRATION NUMBER

DRKS 00027299.

The Short and Long of COVID-19: A Review of Acute and Chronic Radiologic Pulmonary Manifestations of SARS-2-CoV and Their Clinical Significance

Coronavirus disease 2019 (COVID-19) pneumonia has had catastrophic effects worldwide. Radiology, in particular computed tomography (CT) imaging, has proven to be valuable in the diagnosis, prognostication, and longitudinal assessment of those diagnosed with COVID-19 pneumonia. This article will review acute and chronic pulmonary radiologic manifestations of COVID-19 pneumonia with an emphasis on CT and also highlighting histopathology, relevant clinical details, and some notable challenges when interpreting the literature.

Clinical characteristics, imaging, and lung function among patients with persistent dyspnea of COVID-19: a retrospective observational cohort study

The available medical literature on lung function and corresponding clinical characteristics among symptomatic survivors of Corona Virus Disease 2019 (long COVID) is sparse. Primary physicians referred patients who manifested persistent dyspnea months after their index case of infection to a designated clinic. Patients underwent symptom-driven, quality-of-life, physical, and focused respiratory [pulmonary function tests and computed tomography (CT) of the chest] evaluations and were followed over time. In this paper, we present our findings. Patients with abnormal CT imaging were more likely to be of advanced age and to have been hospitalized during their COVID-19 infection. Forced exhaled volume in the first second, forced vital capacity (FVC), total lung capacity, and diffusion capacity of carbon monoxide measurements were found to be significantly lower in patients with abnormal CT imaging. Multivariate regression of clinical characteristics uncovered a significant association between FVC, body mass index, history of hospitalization, and diabetes mellitus. In conclusion, longer-term studies will help further our understanding of the risk factors, disease course, and prognosis of long COVID patients.

Incidence and risk factors for long COVID in children with COVID-19 pneumonia

BACKGROUND AND OBJECTIVE

There are only a few reports of long COVID including pulmonary function in children after COVID-19 pneumonia. We determined the incidence of long COVID and abnormal pulmonary function in those children and identify risk factors.

METHODS

This cohort study enrolled children admitted with COVID-19 pneumonia during 2021-2022. We gathered clinical characteristics during admission and at follow-up 3 months after.

RESULTS

We determined the incidence of long COVID at 39.7% (95% confidence interval [CI]: 30.7%-49.1%). All severe pneumonia cases consistently reported persistent symptoms. Exercise intolerance, cough, and fatigue were the three most common persistent symptoms in 26 (22.4%), 21 (18.1%), and 18 (15.5%) of the patients, respectively. At the follow-up, 21 cases (18.1%) demonstrated persistent abnormal chest radiographs. Three cases (6.9%) demonstrated restrictive ventilatory defects. Among those, one case (2.3%) demonstrated concomitant diffusion defect. Three cases (6.0%) demonstrated exercise-induced hypoxemia after the 6-minute walk test. Comparing spirometry variables between children with long COVID and without revealed significant difference of FEF25-75 (z score) between two groups. Age [adjusted OR (95% CI): 1.13 (1.05-1.22), p value 0.002], allergic diseases [adjusted OR (95% CI): 4.05 (1.36-12.06), p value 0.012], and living in polluted areas [adjusted OR (95% CI): 2.73 (1.18-6.33), p value 0.019] were significantly associated with long COVID.

CONCLUSION

A significant percentage of children developed long COVID after COVID-19 pneumonia. We should give additional attention to those who have exercise intolerance, chronic cough, or fatigue, especially older children, severe cases, children with allergic diseases, and those living in polluted areas.

Research progress of post-acute sequelae after SARS-CoV-2 infection

SARS-CoV-2 has spread rapidly worldwide and infected hundreds of millions of people worldwide. With the increasing number of COVID-19 patients discharged from hospitals, the emergence of its associated complications, sequelae, has become a new global health crisis secondary to acute infection. For the time being, such complications and sequelae are collectively called "Post-acute sequelae after SARS-CoV-2 infection (PASC)", also referred to as "long COVID" syndrome. Similar to the acute infection period of COVID-19, there is also heterogeneity in PASC. This article reviews the various long-term complications and sequelae observed in multiple organ systems caused by COVID-19, pathophysiological mechanisms, diagnosis, and treatment of PASC, aiming to raise awareness of PASC and optimize management strategies.

Review of Hyperpolarized Pulmonary Functional 129 Xe MR for Long-COVID

The respiratory consequences of acute COVID-19 infection and related symptoms tend to resolve 4 weeks post-infection. However, for some patients, new, recurrent, or persisting symptoms remain beyond the acute phase and persist for months, post-infection. The symptoms that remain have been referred to as long-COVID. A number of research sites employed 129 Xe magnetic resonance imaging (MRI) during the pandemic and evaluated patients post-infection, months after hospitalization or home-based care as a way to better understand the consequences of infection on 129 Xe MR gas-exchange and ventilation imaging. A systematic review and comprehensive search were employed using MEDLINE via PubMed (April 2023) using the National Library of Medicine's Medical Subject Headings and key words: post-COVID-19, MRI, 129 Xe, long-COVID, COVID pneumonia, and post-acute COVID-19 syndrome. Fifteen peer-reviewed manuscripts were identified including four editorials, a single letter to the editor, one review article, and nine original research manuscripts (2020-2023). MRI and MR spectroscopy results are summarized from these prospective, controlled studies, which involved small sample sizes ranging from 9 to 76 participants. Key findings included: 1) 129 Xe MRI gas-exchange and ventilation abnormalities, 3 months post-COVID-19 infection, and 2) a combination of MRI gas-exchange and ventilation abnormalities alongside persistent symptoms in patients hospitalized and not hospitalized for COVID-19, 1-year post-infection. The persistence of respiratory symptoms and 129 Xe MRI abnormalities in the context of normal or nearly normal pulmonary function test results and chest computed tomography (CT) was consistent. Longitudinal improvements were observed in long-term follow-up of long-COVID patients but mean 129 Xe gas-exchange, ventilation heterogeneity values and symptoms remained abnormal, 1-year post-infection. Pulmonary functional MRI using inhaled hyperpolarized 129 Xe gas has played a role in detecting gas-exchange and ventilation abnormalities providing complementary information that may help develop our understanding of the root causes of long-COVID. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 5.

Radiomics analysis for distinctive identification of COVID-19 pulmonary nodules from other benign and malignant counterparts

This observational study investigated the potential of radiomics as a non-invasive adjunct to CT in distinguishing COVID-19 lung nodules from other benign and malignant lung nodules. Lesion segmentation, feature extraction, and machine learning algorithms, including decision tree, support vector machine, random forest, feed-forward neural network, and discriminant analysis, were employed in the radiomics workflow. Key features such as Idmn, skewness, and long-run low grey level emphasis were identified as crucial in differentiation. The model demonstrated an accuracy of 83% in distinguishing COVID-19 from other benign nodules and 88% from malignant nodules. This study concludes that radiomics, through machine learning, serves as a valuable tool for non-invasive discrimination between COVID-19 and other benign and malignant lung nodules. The findings suggest the potential complementary role of radiomics in patients with COVID-19 pneumonia exhibiting lung nodules and suspicion of concurrent lung pathologies. The clinical relevance lies in the utilization of radiomics analysis for feature extraction and classification, contributing to the enhanced differentiation of lung nodules, particularly in the context of COVID-19.

Crucial role played by CK8+ cells in mediating alveolar injury remodeling for patients with COVID-19

The high risk of SARS-CoV-2 infection and reinfection and the occurrence of post-acute pulmonary sequelae have highlighted the importance of understanding the mechanism underlying lung repair after injury. To address this concern, comparative and systematic analyses of SARS-CoV-2 infection in COVID-19 patients and animals were conducted. In the lungs of nine patients who died of COVID-19 and one recovered from COVID-19 but died of unrelated disease in early 2020, damage-related transient progenitor (DATP) cells expressing CK8 marker proliferated significantly. These CK8+ DATP cells were derived from bronchial CK5+ basal cells. However, they showed different cell fate toward differentiation into type I alveolar cells in the deceased and convalescent patients, respectively. By using a self-limiting hamster infection model mimicking the dynamic process of lung injury remodeling in mild COVID-19 patients, the accumulation and regression of CK8+ cell marker were found to be closely associated with the disease course. Finally, we examined the autopsied lungs of two patients who died of infection by the recent Omicron variant and found that they only exhibited mild pathological injury with no CK8+ cell proliferation. These results indicate a clear pulmonary cell remodeling route and suggest that CK8+ DATP cells play a primary role in mediating alveolar remodeling, highlighting their potential applications as diagnostic markers and therapeutic targets.

Low Field MRI Surveillance 6-24 Months Post-acute COVID-19 Pneumonia: Factors Influencing Severity and Evolution of Lung Opacities

RATIONALE AND OBJECTIVES

To determine factors influencing low-field MRI lung opacity severity 6-24 months after acute Covid-19 pneumonia.

MATERIALS AND METHODS

104 post-acute Covid-19 patients with 167 MRI exams were included. 32 patients had more than one exam, and 63 exams were serial exams. Pulmonary findings were graded on a scale of 0-4 by quadrant, total score ranging from 0 (no opacity) to 16 (opacity > 75%), and score >8 considered moderate and >12 severe opacity. Kruskal-Wallis, Mann-Whitney, and Spearman rank correlation was used to assess the association of clinical and demographic factors with MR opacity severity at time intervals from acute infection. Random coefficients regression was used to assess whether opacity score changed over time.

RESULTS

Severity of initial illness was associated with increased MR opacity score at timeframes up to 24 months (p < .05). Among the 167 exams, moderate to severe MR opacities (total opacity score >8) were identified in 33% of exams beyond 6 months: 37% at 6 - <12 months (n = 23/63); 31% at 12- < 18 months (n = 13/42); 25% at 18- < 24 months (n = 6/24); and 50% at > 24 months (n = 3/6). No significant change in total opacity score over time was identified by random coefficients regression. Among the 32 patients with serial exams, 11 demonstrated no change in opacity score from initial to final exam, 10 decrease in score (mean 2.3, stdev 1.25, range 1-4), and 11 increase in score (average 2.8, stdev 1.48, range 1-7).

CONCLUSION

Initial Covid-19 disease severity was associated with increased MRI total opacity score at time intervals up to 24 months, and moderate to severe opacities were commonly identified by low-field MRI beyond 6 months from acute illness.

Functional Impairment in Small Airways Associated With the Breathlessness Symptoms in Long-Coronavirus Disease

PURPOSE

This study aimed to determine the association between functional impairment in small airways and symptoms of dyspnea in patients with Long-coronavirus disease (COVID), using imaging and computational modeling analysis.

PATIENTS AND METHODS

Thirty-four patients with Long-COVID underwent thoracic computed tomography and hyperpolarized Xenon-129 magnetic resonance imaging (HP Xe MRI) scans. Twenty-two answered dyspnea-12 questionnaires. We used a computed tomography-based full-scale airway network (FAN) flow model to simulate pulmonary ventilation. The ventilation distribution projected on a coronal plane and the percentage lobar ventilation modeled in the FAN model were compared with the HP Xe MRI data. To assess the ventilation heterogeneity in small airways, we calculated the fractal dimensions of the impaired ventilation regions in the HP Xe MRI and FAN models.

RESULTS

The ventilation distribution projected on a coronal plane showed an excellent resemblance between HP Xe MRI scans and FAN models (structure similarity index: 0.87 ± 0.04). In both the image and the model, the existence of large clustered ventilation defects was not identifiable regardless of dyspnea severity. The percentage lobar ventilation of the HP Xe MRI and FAN model showed a strong correlation (ρ = 0.63, P < 0.001). The difference in the fractal dimension of impaired ventilation zones between the low and high dyspnea-12 score groups was significant (HP Xe MRI: 1.97 [1.89 to 2.04] and 2.08 [2.06 to 2.14], P = 0.005; FAN: 2.60 [2.59 to 2.64] and 2.64 [2.63 to 2.65], P = 0.056).

CONCLUSIONS

This study has identified a potential association of small airway functional impairment with breathlessness in Long-COVID, using fractal analysis of HP Xe MRI scans and FAN models.

Deep spatial proteomics reveals region-specific features of severe COVID-19-related pulmonary injury

As a primary target of severe acute respiratory syndrome coronavirus 2, lung exhibits heterogeneous histopathological changes following infection. However, comprehensive insight into their protein basis with spatial resolution remains deficient, which hinders further understanding of coronavirus disease 2019 (COVID-19)-related pulmonary injury. Here, we generate a region-resolved proteomic atlas of hallmark pathological pulmonary structures by integrating histological examination, laser microdissection, and ultrasensitive proteomics. Over 10,000 proteins are quantified across 71 post-mortem specimens. We identify a spectrum of pathway dysregulations in alveolar epithelium, bronchial epithelium, and blood vessels compared with non-COVID-19 controls, providing evidence for transitional-state pneumocyte hyperplasia. Additionally, our data reveal the region-specific enrichment of functional markers in bronchiole mucus plugs, pulmonary fibrosis, airspace inflammation, and alveolar type 2 cells, uncovering their distinctive features. Furthermore, we detect increased protein expression associated with viral entry and inflammatory response across multiple regions, suggesting potential therapeutic targets. Collectively, this study provides a distinct perspective for deciphering COVID-19-caused pulmonary dysfunction by spatial proteomics.

COVID-19 organizing pneumonia with sudden dyspnea in an asymptomatic survivor

This case shows that COVID-19 survivors can develop delayed-type pneumonia with sudden respiratory distress that responds dramatically to steroid treatment after remaining asymptomatic for more than several weeks, although pulmonary involvement of post-COVID-19 syndrome is often accompanied by long-term and severe sequelae such as pulmonary fibrosis.

Chronic Lung Injury after COVID-19 Pneumonia: Clinical, Radiologic, and Histopathologic Perspectives

With the COVID-19 pandemic having lasted more than 3 years, concerns are growing about prolonged symptoms and respiratory complications in COVID-19 survivors, collectively termed post-COVID-19 condition (PCC). Up to 50% of patients have residual symptoms and physiologic impairment, particularly dyspnea and reduced diffusion capacity. Studies have also shown that 24%-54% of patients hospitalized during the 1st year of the pandemic exhibit radiologic abnormalities, such as ground-glass opacity, reticular opacity, bronchial dilatation, and air trapping, when imaged more than 1 year after infection. In patients with persistent respiratory symptoms but normal results at chest CT, dual-energy contrast-enhanced CT, xenon 129 MRI, and low-field-strength MRI were reported to show abnormal ventilation and/or perfusion, suggesting that some lung injury may not be detectable with standard CT. Histologic patterns in post-COVID-19 lung disease include fibrosis, organizing pneumonia, and vascular abnormality, indicating that different pathologic mechanisms may contribute to PCC. Therefore, a comprehensive imaging approach is necessary to evaluate and diagnose patients with persistent post-COVID-19 symptoms. This review will focus on the long-term findings of clinical and radiologic abnormalities and describe histopathologic perspectives. It also addresses advanced imaging techniques and deep learning approaches that can be applied to COVID-19 survivors. This field remains an active area of research, and further follow-up studies are warranted for a better understanding of the chronic stage of the disease and developing a multidisciplinary approach for patient management.

Pulmonary function assessment after COVID-19 in vaccinated healthcare workers

COVID-19 typically presents with flu-like symptoms due to the viral infection itself. The most severe cases are characterised by lung damage, an important factor in fatal outcome due to alveolar damage. In some cases, patients develop a long COVID with persistent symptoms of chest pain and fatigue. Causes, including organ damage or inflammation, are being investigated. Clinical outcomes are variable and permanent lung damage is not fully understood, while vaccination is effective against severe infection but its effect on respiratory function in mild cases remains uncertain. This retrospective study aims to analyse changes in lung function in HCWs who had COVID-19 between 2020 and 2022, comparing their spirometric test results before and after the pandemic and taking into account their vaccination status. 321 HCWs were included in the study. The study examined spirometric parameters both before and after the pandemic, and all measured outcomes except the FEV1/FVC ratio showed a significant decrease during the study period. We then assessed the association between SARS-CoV-2 infection and changes in lung function parameters, analysing infections in 2020, 2021 and 2022 separately. We found a statistically significant difference in Forced vital capacity (FVC) between infected and non-infected subjects in 2020 and 2021, but not in 2022. To evaluate the protective effect of SARS-CoV-2 vaccination on respiratory function, a linear regression analysis was performed using changes in FVC, Forced expiratory volume in 1 s (FEV1), FVC/FEV1 ratio and Peak expiratory flow (PEF) as dependent variables. The analysis showed that the decline in FVC was significantly lower in subjects who had been vaccinated prior to infection. The study concludes that subclinical SARS-CoV-2 infections in 2020 and 2021 worsened respiratory parameters (FVC and FEV1), but vaccination protected against these effects. Even healthy individuals with previous infections showed respiratory changes, with vaccination providing protection, especially for FVC decline. This highlights the importance of vaccinating healthcare workers against COVID-19.

Plasma proteomics-based biomarkers for predicting response to mesenchymal stem cell therapy in severe COVID-19

BACKGROUND

The objective of this study was to identify potential biomarkers for predicting response to MSC therapy by pre-MSC treatment plasma proteomic profile in severe COVID-19 in order to optimize treatment choice.

METHODS

A total of 58 patients selected from our previous RCT cohort were enrolled in this study. MSC responders (n = 35) were defined as whose resolution of lung consolidation ≥ 51.99% (the median value for resolution of lung consolidation) from pre-MSC to 28 days post-MSC treatment, while non-responders (n = 23) were defined as whose resolution of lung consolidation < 51.99%. Plasma before MSC treatment was detected using data-independent acquisition (DIA) proteomics. Multivariate logistic regression analysis was used to identify pre-MSC treatment plasma proteomic biomarkers that might distinguish between responders and non-responders to MSC therapy.

RESULTS

In total, 1101 proteins were identified in plasma. Compared with the non-responders, the responders had three upregulated proteins (CSPG2, CTRB1, and OSCAR) and 10 downregulated proteins (ANXA1, AGRG6, CAPG, DDX55, KV133, LEG10, OXSR1, PICAL, PTGDS, and S100A8) in plasma before MSC treatment. Using logistic regression model, lower levels of DDX55, AGRG6, PICAL, and ANXA1 and higher levels of CTRB1 pre-MSC treatment were predictors of responders to MSC therapy, with AUC of the ROC at 0.910 (95% CI 0.818-1.000) in the training set. In the validation set, AUC of the ROC was 0.767 (95% CI 0.459-1.000).

CONCLUSIONS

The responsiveness to MSC therapy appears to depend on baseline level of DDX55, AGRG6, PICAL, CTRB1, and ANXA1. Clinicians should take these factors into consideration when making decision to initiate MSC therapy in patients with severe COVID-19.

Lung Ultrasound Elastography by SWE2D and "Fibrosis-like" Computed Tomography Signs after COVID-19 Pneumonia: A Follow-Up Study

The aim of this study was to assess the shear wave velocity by LUS elastography (SWE2D) for the evaluation of superficial lung stiffness after COVID-19 pneumonia, according to "fibrosis-like" signs found by Computed Tomography (CT), considering the respiratory function. Seventy-nine adults participated in the study 42 to 353 days from symptom onset. Paired evaluations (SWE2D and CT) were performed along with the assessment of arterial blood gases and spirometry, three times with 100 days in between. During the follow-up and within each evaluation, the SWE2D velocity changed over time (MANOVA, p < 0.05) according to the extent of "fibrosis-like" CT signs by lung lobe (ANOVA, p < 0.05). The variability of the SWE2D velocity was consistently related to the first-second forced expiratory volume and the forced vital capacity (MANCOVA, p < 0.05), which changed over time with no change in blood gases. Covariance was also observed with age and patients' body mass index, the time from symptom onset until hospital admission, and the history of diabetes in those who required intensive care during the acute phase (MANCOVA, p < 0.05). After COVID-19 pneumonia, SWE2D velocity can be related to the extent and regression of "fibrotic-like" involvement of the lung lobes, and it could be a complementary tool in the follow-up after COVID-19 pneumonia.

Successful management of concurrent COVID-19 and Pneumocystis Jirovecii Pneumonia in kidney transplant recipients: a case series

BACKGROUND

Pneumocystis pneumonia (PCP) is a life-threatening pulmonary fungal infection that predominantly affects immunocompromised individuals, including kidney transplant recipients. Recent years have witnessed a rising incidence of PCP in this vulnerable population, leading to graft loss and increased mortality. Immunosuppression, which is essential in transplant recipients, heightens susceptibility to viral and opportunistic infections, magnifying the clinical challenge. Concurrently, the global impact of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been profound. Kidney transplant recipients have faced severe outcomes when infected with SARS-CoV-2, often requiring intensive care. Co-infection with COVID-19 and PCP in this context represents a complex clinical scenario that requires precise management strategies, involving a delicate balance between immunosuppression and immune activation. Although there have been case reports on management of COVID-19 and PCP in kidney transplant recipients, guidance on how to tackle these infections when they occur concurrently remains limited.

CASE PRESENTATIONS

We have encountered four kidney transplant recipients with concurrent COVID-19 and PCP infection. These patients received comprehensive treatment that included adjustment of their maintenance immunosuppressive regimen, anti-pneumocystis therapy, treatment for COVID-19 and other infections, and symptomatic and supportive care. After this multifaceted treatment strategy, all of these patients improved significantly and had favorable outcomes.

CONCLUSIONS

We have successfully managed four kidney transplant recipients co-infected with COVID-19 and PCP. While PCP is a known complication of immunosuppressive therapy, its incidence in patients with COVID-19 highlights the complexity of dual infections. Our findings suggest that tailored immunosuppressive regimens, coupled with antiviral and antimicrobial therapies, can lead to clinical improvement in such cases. Further research is needed to refine risk assessment and therapeutic strategies, which will ultimately enhance the care of this vulnerable population.

The long-term health outcomes, pathophysiological mechanisms and multidisciplinary management of long COVID

There have been hundreds of millions of cases of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). With the growing population of recovered patients, it is crucial to understand the long-term consequences of the disease and management strategies. Although COVID-19 was initially considered an acute respiratory illness, recent evidence suggests that manifestations including but not limited to those of the cardiovascular, respiratory, neuropsychiatric, gastrointestinal, reproductive, and musculoskeletal systems may persist long after the acute phase. These persistent manifestations, also referred to as long COVID, could impact all patients with COVID-19 across the full spectrum of illness severity. Herein, we comprehensively review the current literature on long COVID, highlighting its epidemiological understanding, the impact of vaccinations, organ-specific sequelae, pathophysiological mechanisms, and multidisciplinary management strategies. In addition, the impact of psychological and psychosomatic factors is also underscored. Despite these crucial findings on long COVID, the current diagnostic and therapeutic strategies based on previous experience and pilot studies remain inadequate, and well-designed clinical trials should be prioritized to validate existing hypotheses. Thus, we propose the primary challenges concerning biological knowledge gaps and efficient remedies as well as discuss the corresponding recommendations.

Lactate dehydrogenase contribution to symptom persistence in long COVID: A pooled analysis

There's critical need for risk predictors in long COVID. This meta-analysis evaluates the evidence for an association between plasma lactate dehydrogenase (LDH) and long COVID and explores the contribution of LDH to symptoms persistent across the distinct post-acute sequelae of COVID-19 (PASC) domains. PubMed, EMBASE, Web of Science, and Google Scholar were searched for articles published up to 20 March 2023 for studies that reported data on LDH levels in COVID-19 survivors with and without PASC. Random-effect meta-analysis was employed to estimate the standardized mean difference (SMD) with corresponding 95% confidence interval of each outcome. There were a total of 8289 study participants (3338 PASC vs. 4951 controls) from 46 studies. Our meta-analysis compared to the controls showed a significant association between LDH elevation and Resp-PASC [SMD = 1.07, 95%CI = 0.72, 1.41, p = 0.01] but not Cardio-PASC [SMD = 1.79, 95%CI = -0.02, 3.61, p = 0.05], Neuro-PASC [SMD = 0.19, 95%CI = -0.24, 0.61, p = 0.40], and Gastrointestinal-PASC [SMD = 0.45, 95%CI = -1.08, 1.98, p = 0.56]. This meta-analysis suggests elevated LDH can be used for predicting Resp-PASC, but not Cardio-PASC, Neuro-PASC or gastrointestinal-PASC. Thus, elevated plasma LDH following COVID infection may be considered as a disease biomarker.

Clinical and pulmonary function analysis in long-COVID revealed that long-term pulmonary dysfunction is associated with vascular inflammation pathways and metabolic syndrome

Introduction

Long-term pulmonary dysfunction (L-TPD) is one of the most critical manifestations of long-COVID. This lung affection has been associated with disease severity during the acute phase and the presence of previous comorbidities, however, the clinical manifestations, the concomitant consequences and the molecular pathways supporting this clinical condition remain unknown. The aim of this study was to identify and characterize L-TPD in patients with long-COVID and elucidate the main pathways and long-term consequences attributed to this condition by analyzing clinical parameters and functional tests supported by machine learning and serum proteome profiling.

Methods

Patients with L-TPD were classified according to the results of their computer-tomography (CT) scan and diffusing capacity of the lungs for carbon monoxide adjusted for hemoglobin (DLCOc) tests at 4 and 12-months post-infection.

Results

Regarding the acute phase, our data showed that L-TPD was favored in elderly patients with hypertension or insulin resistance, supported by pathways associated with vascular inflammation and chemotaxis of phagocytes, according to computer proteomics. Then, at 4-months post-infection, clinical and functional tests revealed that L-TPD patients exhibited a restrictive lung condition, impaired aerobic capacity and reduced muscular strength. At this time point, high circulating levels of platelets and CXCL9, and an inhibited FCgamma-receptor-mediated-phagocytosis due to reduced FcγRIII (CD16) expression in CD14+ monocytes was observed in patients with L-TPD. Finally, 1-year post infection, patients with L-TPD worsened metabolic syndrome and augmented body mass index in comparison with other patient groups.

Discussion

Overall, our data demonstrated that CT scan and DLCOc identified patients with L-TPD after COVID-19. This condition was associated with vascular inflammation and impair phagocytosis of virus-antibody immune complexes by reduced FcγRIII expression. In addition, we conclude that COVID-19 survivors required a personalized follow-up and adequate intervention to reduce long-term sequelae and the appearance of further metabolic diseases.

Risk of subsequent lower respiratory tract infection (LRTI) after hospitalization for COVID-19 LRTI and non-COVID-19 LRTI: a retrospective cohort study

BACKGROUND

Respiratory pathogens, including SARS-CoV-2, can cause pulmonary structural damage and physiologic impairment, which may increase the risk of subsequent lower respiratory tract infections (LRTI). Prior hospitalization for any reason is a risk factor for LRTI, but data on the risk of subsequent new-onset LRTI following hospitalization for COVID-19 LRTI or non-COVID-19 LRTI are needed to inform strategies for immunizations targeting respiratory pathogens.

METHODS

We conducted a retrospective cohort study at Kaiser Permanente Southern California (KPSC) among adults hospitalized from 3/1/2020 to 5/31/2022, excluding labor and delivery. We categorized individuals into 3 mutually exclusive baseline exposure groups: those hospitalized for COVID-19 LRTI, those hospitalized for non-COVID-19 LRTI, and those hospitalized for all other causes without LRTI or COVID-19 ("non-LRTI"). Following hospital discharge, patients were followed up for new-onset LRTI, beginning 30 antibiotic-free days after hospital discharge until 8/31/2022. We used multivariable cause-specific Cox regression with time-varying covariates to estimate hazard ratios (HR) of new-onset LRTI comparing those hospitalized for COVID-19 LRTI or non-COVID-19 LRTI to those hospitalized for non-LRTI, adjusting for demographic and clinical characteristics.

RESULTS

The study included 22,417 individuals hospitalized for COVID-19 LRTI, 12,795 individuals hospitalized for non-COVID-19 LRTI, and 176,788 individuals hospitalized for non-LRTI. Individuals hospitalized for non-COVID-19 LRTI were older and had more comorbidities than those hospitalized for COVID-19 LRTI or non-LRTI. Incidence rates per 1,000 person-years (95% CI) of new-onset LRTI were 52.5 (51.4-53.6) among individuals hospitalized for COVID-19 LRTI, 253.5 (243.7-263.6) among those hospitalized for non-COVID-19 LRTI, and 52.5 (51.4-53.6) among those hospitalized for non-LRTI. The adjusted hazard of new-onset LRTI during follow-up was 20% higher among individuals hospitalized for COVID-19 LRTI (HR 1.20 [95% CI: 1.12-1.28]) and 301% higher among individuals hospitalized for non-COVID-19 LRTI (HR 3.01 [95% CI: 2.87-3.15]) compared to those hospitalized for non-LRTI.

CONCLUSION

The risk of new-onset LRTI following hospital discharge was high, particularly among those hospitalized for non-COVID-19 LRTI, but also for COVID-19 LRTI. These data suggest that immunizations targeting respiratory pathogens, including COVID-19, should be considered for adults hospitalized for LRTI prior to hospital discharge.

Is Pulmonary Involvement a Distinct Phenotype of Post-COVID-19?

(1) Background: COVID-19 infection often provokes symptoms lasting many months: most commonly fatigue, dyspnea, myalgia and mental distress symptoms. In this study, we searched for clinical features of post-COVID-19 condition (PCC) and differences between patients with and without pulmonary involvement. (2) Methods: A total of 282 patients with a mean age of 57 years (SD +/- 12 years) underwent assessment up to 12 weeks after COVID-19 recovery. The course of acute disease, past medical history and clinical symptoms were gathered; pulmonary function tests were performed; radiographic studies were assessed and follow-up examinations were conducted. Patients with and without detectable pulmonary lesions were divided into separate groups. (3) Results: Patients within the pulmonary group were more often older (59 vs. 51 y.o.; p < 0.001) males (p = 0.002) that underwent COVID-19-related hospitalization (p < 0.001) and were either ex- or active smokers with the median of 20 pack-years. We also managed to find correlations with hypertension (p = 0.01), liver failure (p = 0.03), clinical symptoms such as dyspnea (p < 0.001), myalgia (p = 0.04), headache (p = 0.009), sleeplessness (p = 0.046), pulmonary function tests (such as FVC, TLCO, RV and TLC; p < 0.001) and several basic laboratory tests (D-dimer, cardiac troponin, WBC, creatinine and others). (4) Conclusions: Our results indicate that initial pulmonary involvement alters the PCC, and it can be used to individualize clinical approaches.

METTL3-mediated N6-methyladenosine exacerbates ferroptosis via m6A-IGF2BP2-dependent mitochondrial metabolic reprogramming in sepsis-induced acute lung injury

Neutrophil extracellular traps (NETs), released by polymorphonuclear neutrophils (PMNs), exert a robust antimicrobial function in infectious diseases such as sepsis. NETs also contribute to the pathogenesis and exacerbation of sepsis. Although the lung is highly vulnerable to infections, few studies have explored the role of NETs in sepsis-induced acute lung injury (SI-ALI). We demonstrate that NETs induce SI-ALI via enhanced ferroptosis in alveolar epithelial cells. Our findings reveal that the excessive release of NETs in patients and mice with SI-ALI is accompanied by upregulation of ferroptosis depending on METTL3-induced m6A modification of hypoxia-inducible factor-1α (HIF-1α) and subsequent mitochondrial metabolic reprogramming. In addition to conducting METTL3 overexpression and knockdown experiments in vitro, we also investigated the impact of ferroptosis on SI-ALI caused by NETs in a caecum ligation and puncture (CLP)-induced SI-ALI model using METTL3 condition knockout (CKO) mice and wild-type mice. Our results indicate the crucial role of NETs in the progression of SI-ALI via NET-activated METTL3 m6A-IGF2BP2-dependent m6A modification of HIF-1α, which further contributes to metabolic reprogramming and ferroptosis in alveolar epithelial cells.

Can adipokines predict clinical prognosis and post-COVID lung sequelae?

BACKGROUND

Adipokines play an important role in the regulation of inflammatory responses toward infections, including COVID-19. This study aimed to investigate the role of chemerin, adiponectin, and leptin in prognosis and post-COVID lung sequelae in hospitalized patients with COVID-19.

METHODS

Serum levels of the three adipokines were measured upon admission of polymerase chain reaction-confirmed patients with COVID-19 who were followed up for 6 months for the clinical outcome and lung sequelae formation.

RESULTS

A total of 77 patients were included in the study. Of the 77 patients, 58.4% were males, and the median age was 63.2 ± 18.3 years. Fifty-one patients (66.2%) had a good prognosis. Among adipokines, only chemerin was significantly lower in the bad prognosis group (P < 0.05), and the serum levels showed a negative correlation with age (rho = -0.238; P < 0.05). Leptin levels were negatively correlated with gamma glutamyl transferase levels, which were significantly higher in the bad prognostic group (rho = -0.240; P < 0.05). Twenty-four patients had no lung sequelae, and 20 developed sequelae within 6 months after infection. Chemerin/adiponectin ratio with a cut-off value of 0.96 and an area under the curve 0.679 (P < 0.05) might predict the sequelae formation.

CONCLUSIONS

Chemerin levels are lower, especially in patients with a bad prognosis, and the chemerin/adiponectin ratio might predict the development of lung sequelae in patients with COVID-19.

Post-COVID-19 Pulmonary Fibrosis: Facts-Challenges and Futures: A Narrative Review

Patients with coronavirus disease 2019 (COVID-19) usually suffer from post-acute sequelae of coronavirus disease 2019 (PASC). Pulmonary fibrosis (PF) has the most significant long-term impact on patients' respiratory health, called post-COVID-19 pulmonary fibrosis (PC19-PF). PC19- PF can be caused by acute respiratory distress syndrome (ARDS) or pneumonia due to COVID-19. The risk factors of PC19-PF, such as older age, chronic comorbidities, the use of mechanical ventilation during the acute phase, and female sex, should be considered. Individuals with COVID-19 pneumonia symptoms lasting at least 12 weeks following diagnosis, including cough, dyspnea, exertional dyspnea, and poor saturation, accounted for nearly all disease occurrences. PC19-PF is characterized by persistent fibrotic tomographic sequelae associated with functional impairment throughout follow-up. Thus, clinical examination, radiology, pulmonary function tests, and pathological findings should be done to diagnose PC19-PF patients. PFT indicated persistent limitations in diffusion capacity and restrictive physiology, despite the absence of previous testing and inconsistency in the timeliness of assessments following acute illness. It has been hypothesized that PC19-PF patients may benefit from idiopathic pulmonary fibrosis treatment to prevent continued infection-related disorders, enhance the healing phase, and manage fibroproliferative processes. Immunomodulatory agents might reduce inflammation and the length of mechanical ventilation during the acute phase of COVID-19 infection, and the risk of the PC19-PF stage. Pulmonary rehabilitation, incorporating exercise training, physical education, and behavioral modifications, can improve the physical and psychological conditions of patients with PC19-PF.

Virtual reality for assessing stereopsis performance and eye characteristics in Post-COVID

In 2019, we faced a pandemic due to the coronavirus disease (COVID-19), with millions of confirmed cases and reported deaths. Even in recovered patients, symptoms can be persistent over weeks, termed Post-COVID. In addition to common symptoms of fatigue, muscle weakness, and cognitive impairments, visual impairments have been reported. Automatic classification of COVID and Post-COVID is researched based on blood samples and radiation-based procedures, among others. However, a symptom-oriented assessment for visual impairments is still missing. Thus, we propose a Virtual Reality environment in which stereoscopic stimuli are displayed to test the patient's stereopsis performance. While performing the visual tasks, the eyes' gaze and pupil diameter are recorded. We collected data from 15 controls and 20 Post-COVID patients in a study. Therefrom, we extracted features of three main data groups, stereopsis performance, pupil diameter, and gaze behavior, and trained various classifiers. The Random Forest classifier achieved the best result with 71% accuracy. The recorded data support the classification result showing worse stereopsis performance and eye movement alterations in Post-COVID. There are limitations in the study design, comprising a small sample size and the use of an eye tracking system.

Correlation between Hepatocyte Growth Factor (HGF) with D-Dimer and Interleukin-6 as Prognostic Markers of Coagulation and Inflammation in Long COVID-19 Survivors

In general, an individual who experiences the symptoms of Severe Acute Respiratory Syndrome Coronavirus 2 or SARS-CoV-2 infection is declared as recovered after 2 weeks. However, approximately 10-20% of these survivors have been reported to encounter long-term health problems, defined as 'long COVID-19', e.g., blood coagulation which leads to stroke with an estimated incidence of 3%, and pulmonary embolism with 5% incidence. At the time of infection, the immune response produces pro-inflammatory cytokines that stimulate stromal cells to produce pro-hepatocyte growth factor (pro-HGF) and eventually is activated into hepatocyte growth factor (HGF), which helps the coagulation process in endothelial and epithelial cells. HGF is a marker that appears as an inflammatory response that leads to coagulation. Currently, there is no information on the effect of SARS-CoV-2 infection on serum HGF concentrations as a marker of the prognosis of coagulation in long COVID-19 survivors. This review discusses the pathophysiology between COVID-19 and HGF, IL-6, and D-dimer.

The added value of lung perfusion scintigraphy semiquantitative measures in post-COVID patients with persistent dyspnea without pulmonary embolism

BACKGROUND

Persistent dyspnea is frequent in post-COVID patients, even in the absence of pulmonary embolism (PE). In this scenario, the role of lung perfusion scintigraphy is unclear. The present study correlated scintigraphy-based semiquantitative perfusion parameters with chest high-resolution computed tomography (hrCT) volumetric indexes and clinical data in post-COVID patients with persistent dyspnea.

RESEARCH DESIGN AND METHODS

Sixty patients (30 post-COVID and 30 not previously affected by COVID-19) with persistent dyspnea submitted to lung perfusion scintigraphy and hrCT were retrospectively recruited. Perfusion rates of the pulmonary fields and hrCT-based normalized inflated, emphysematous, infiltrated, collapsed, and vascular lung volumes were calculated. Inflammatory and coagulation biomarkers were collected. PE at imaging was an exclusion criterion.

RESULTS

Compared to controls, reduced perfusion rates of the lower pulmonary fields and higher perfusion rates of the middle ones were observed in post-COVID patients, while hrCT findings were superimposable between the two groups. Perfusion rates of lower pulmonary fields were significantly associated only with abnormal lung volumes at hrCT.

CONCLUSIONS

In post-COVID dyspnea without PE, lung perfusion scintigraphy may reveal a pulmonary involvement not detectable by hrCT. Post-COVID patients may show decreased perfusion rates of lower pulmonary fields in the presence of normal vascular density and markers of inflammation/coagulation.

Radiological lung sequelae, functional status and symptoms in older patients 3 and 6 months after hospitalization for COVID-19 pneumonia

The aim of our study was to assess the lung sequelae and clinical consequences 3 and 6 months after hospitalization for COVID-19 pneumonia in older patients. An observational study was conducted on 55 patients aged 65 years and older. Activities of daily living (ADL) and clinical frailty scale (CFS) were assessed at baseline and after 3 months. Both quantitative assessment at chest high-resolution computed tomography (CT) and semi-quantitative severity score (CTSS) were performed at baseline and after 3 and 6 months. Mean age: 82.3 ± 7.1 years. Male prevalence: 56.4%. After 6 months, ground-glass opacities (GGO) were still detectable in 22% of subjects, while consolidations were no longer appreciable. During follow-up, CTSS reached an overall median score of zero after 6 months. Fibrotic-like changes were found in 40% of subjects with an overall median score of 0 (0-5) points, being more prevalent in males. Patients reporting worsening ADL and CFS were 10.9% and 45.5%, respectively. They were associated with the burden of comorbidities, especially history of heart failure and chronic obstructive pulmonary disease at baseline. Amnesic disorders, exertional dyspnea, and fatigue were the most relevant symptoms reported. No association emerged between persistent or new-onset symptoms and evidence of fibrotic-like changes. The typical chest CT abnormalities of the COVID-19 pneumonia acute phase resolved in most of our older patients. Mild fibrotic-like changes persisted in less than half of the patients, especially males, without significantly affecting the functional status and frailty condition, which instead were more likely associated with pre-existing comorbidities.

Multicentre study on the accuracy of lung ultrasound in the diagnosis and monitoring of respiratory sequelae in the medium and long term in patients with COVID-19

Introduction

Lung ultrasound (LUS) has proven to be a more sensitive tool than radiography (X-ray) to detect alveolar-interstitial involvement in COVID-19 pneumonia. However, its usefulness in the detection of possible pulmonary alterations after overcoming the acute phase of COVID-19 is unknown. In this study we proposed studying the utility of LUS in the medium- and long-term follow-up of a cohort of patients hospitalized with COVID-19 pneumonia.

Materials and methods

This was a prospective, multicentre study that included patients, aged over 18 years, at 3 ± 1 and 12 ± 1 months after discharge after treatment for COVID-19 pneumonia. Demographic variables, the disease severity, and analytical, radiographic, and functional clinical details were collected. LUS was performed at each visit and 14 areas were evaluated and classified with a scoring system whose global sum was referred to as the "lung score." Two-dimensional shear wave elastography (2D-SWE) was performed in 2 anterior areas and in 2 posterior areas in a subgroup of patients. The results were compared with high-resolution computed tomography (CT) images reported by an expert radiologist.

Results

A total of 233 patients were included, of whom 76 (32.6%) required Intensive Care Unit (ICU) admission; 58 (24.9%) of them were intubated and non-invasive respiratory support was also necessary in 58 cases (24.9%). Compared with the results from CT images, when performed in the medium term, LUS showed a sensitivity (S) of 89.7%, specificity (E) 50%, and an area under the curve (AUC) of 78.8%, while the diagnostic usefulness of X-ray showed an S of 78% and E of 47%. Most of the patients improved in the long-term evaluation, with LUS showing an efficacy with an S of 76% and E of 74%, while the X-ray presented an S of 71% and E of 50%. 2D-SWE data were available in 108 (61.7%) patients, in whom we found a non-significant tendency toward the presentation of a higher shear wave velocity among those who developed interstitial alterations, with a median kPa of 22.76 ± 15.49) versus 19.45 ± 11.39; p = 0.1).

Conclusion

Lung ultrasound could be implemented as a first-line procedure in the evaluation of interstitial lung sequelae after COVID-19 pneumonia.

Bronchoscopy in the post-acute phase of COVID-19: an observational study

BACKGROUND

Bronchoscopy is a useful technique adopted in the management of patients with COVID-19. 10-40% of COVID-19 survivors experience persistent symptoms. A comprehensive description of the utility and safety of bronchoscopy in the management of patients with COVID-19 sequelae is lacking. The aim of the study was to evaluate the role of bronchoscopy in patients with suspected post-acute sequelae of COVID-19.

METHODS

An observational, retrospective study was carried out in Italy. Patients requiring bronchoscopy for suspected COVID-19 sequelae were enrolled.

RESULTS

45 (21, 46.7%, female) patients were recruited. Bronchoscopy was more frequently indicated for patients with a previous critical disease. The most frequent indications were tracheal complications, mostly performed in patients who were hospitalized during the acute phase than treated at home (14, 48.3% VS. 1, 6.3%; p-value: 0.007) and persistent parenchymal infiltrates, more frequent in those treated at home (9, 56.3% VS. 5, 17.2%; p-value: 0.008). 3 (6.6%) patients after the first bronchoscopy required higher oxygen flow. Four patients were diagnosed with lung cancer.

CONCLUSION

Bronchoscopy is a useful and safe technique in patients with suspected post-acute sequelae of COVID-19. The severity of acute disease plays a role in the rate and indications of bronchoscopy. Endoscopic procedures were mostly performed for tracheal complications in critical, hospitalized patients and for persistent lung parenchymal infiltrates in mild-moderate infections treated at home.

Artificial intelligence for reducing the radiation burden of medical imaging for the diagnosis of coronavirus disease

Medical imaging has been intensively employed in screening, diagnosis and monitoring during the COVID-19 pandemic. With the improvement of RT-PCR and rapid inspection technologies, the diagnostic references have shifted. Current recommendations tend to limit the application of medical imaging in the acute setting. Nevertheless, efficient and complementary values of medical imaging have been recognized at the beginning of the pandemic when facing unknown infectious diseases and a lack of sufficient diagnostic tools. Optimizing medical imaging for pandemics may still have encouraging implications for future public health, especially for long-lasting post-COVID-19 syndrome theranostics. A critical concern for the application of medical imaging is the increased radiation burden, particularly when medical imaging is used for screening and rapid containment purposes. Emerging artificial intelligence (AI) technology provides the opportunity to reduce the radiation burden while maintaining diagnostic quality. This review summarizes the current AI research on dose reduction for medical imaging, and the retrospective identification of their potential in COVID-19 may still have positive implications for future public health.

Chest CT Findings after Mild COVID-19 Do Not Explain Persisting Respiratory Symptoms: An Explanatory Study

(1) Background: Lung tissue involvement is frequently observed in acute COVID-19. However, it is unclear whether CT findings at follow-up are associated with persisting respiratory symptoms after initial mild or moderate infection. (2) Methods: Chest CTs of patients with persisting respiratory symptoms referred to the post-COVID-19 outpatient clinic were reassessed for parenchymal changes, and their potential association was evaluated. (3) Results: A total of 53 patients (31 female) with a mean (SD) age of 46 (13) years were included, of whom 89% had mild COVID-19. Median (quartiles) time from infection to CT was 139 (86, 189) days. Respiratory symptoms were dyspnea (79%), cough (42%), and thoracic pain (64%). Furthermore, 30 of 53 CTs showed very discrete and two CTs showed medium parenchymal abnormalities. No severe findings were observed. Mosaic attenuation (40%), ground glass opacity (2%), and fibrotic-like changes (25%) were recorded. No evidence for an association between persisting respiratory symptoms and chest CT findings was found. (4) Conclusions: More than half of the patients with initially mild or moderate infection showed findings on chest CT at follow-up. Respiratory symptoms, however, were not related to any chest CT finding. We, therefore, do not suggest routine chest CT follow-up in this patient group if no other indications are given.

A comprehensive overview on the transmission, pathogenesis, diagnosis, treatment, and prevention of SARS-CoV-2

Severe acute respiratory syndrome coronavirus (SARS-CoV) is a single positive-strand RNA virus that is responsible for the current pandemic that the world has been facing since 2019. The primary route of transmission of SARS-CoV-2 is through respiratory tract transmission. However, other transmission routes such as fecal-oral, vertical transmission, and aerosol-eye also exist. In addition, it has been found that the pathogenesis of this virus involves the binding of the virus's S protein to its host cell surface receptor angiotensin-converting enzyme 2, which results in the subsequent membrane fusion that is required for SARS-CoV-2 to replicate and complete its entire life. The clinical symptoms of patients infected with SARS-CoV-2 can range from asymptomatic to severe. The most common symptoms seen include fever, dry cough, and fatigue. Once these symptoms are observed, a nucleic acid test is done using reverse transcription-polymerase chain reaction. This currently serves as the main confirmatory tool for COVID-19. Despite the fact that no cure has been found for SARS-CoV-2, prevention methods such as vaccines, specific facial mask, and social distancing have proven to be quite effective. It is imperative to have a complete understanding of the transmission and pathogenesis of this virus. To effectively develop new drugs as well as diagnostic tools, more knowledge about this virus would be needed.

HIV and inflammatory markers are associated with persistent COVID-19 symptoms

BACKGROUND

A proportion of COVID19 survivors may present with long-COVID, which is persistent symptoms lasting four or more weeks post SARS-CoV-2 infection. These symptoms may be mild to severe, and may affect different organ-systems of the body.

AIMS

The main objective of this study was to determine the demographic, clinical and immunological factors associated with long COVID.

MATERIALS & METHODS

We conducted a nested case control study, with a total of 94 study participants initially included, and 64 participants matched for age and sex for biomarker analyses.

RESULTS

32/94 (34.1%) of all the participants had long COVID. Respiratory symptoms were the most common (59.5%) followed by the musculoskeletal symptoms (28.1%). HIV was an independent predictor of long COVID (adjusted odds ratio = 2.7; p = .037). In all the 64 matched cases and controls, IFN-β was significantly higher among controls than cases. After stratifying by HIV, IL6 was significantly higher among cases than controls in the HIV- group (2.06 vs. 0.81 pg/mL; p = .02). On the other hand, IFN-β was significantly higher among controls than cases in the HIV+ group (251 vs. 0 pg/mL; p = .01).

CONCLUSION

HIV infection is a risk factor for long COVID, and inflammatory markers associated with long COVID may be slightly different for HIV- and HIV+ individuals.

Inflammation and Epstein-Barr Virus at the Crossroads of Multiple Sclerosis and Post-Acute Sequelae of COVID-19 Infection

Recent studies have strengthened the evidence for Epstein-Barr Virus (EBV) as an important contributing factor in the development of multiple sclerosis (MS). Chronic inflammation is a key feature of MS. EBV+ B cells can express cytokines and exosomes that promote inflammation, and EBV is known to be reactivated through the upregulation of cellular inflammasomes. Inflammation is a possible cause of the breakdown of the blood-brain barrier (BBB), which allows the infiltration of lymphocytes into the central nervous system. Once resident, EBV+ or EBV-specific B cells could both plausibly exacerbate MS plaques through continued inflammatory processes, EBV reactivation, T cell exhaustion, and/or molecular mimicry. Another virus, SARS-CoV-2, the cause of COVID-19, is known to elicit a strong inflammatory response in infected and immune cells. COVID-19 is also associated with EBV reactivation, particularly in severely ill patients. Following viral clearance, continued inflammation may be a contributor to post-acute sequelae of COVID-19 infection (PASC). Evidence of aberrant cytokine activation in patients with PASC supports this hypothesis. If unaddressed, long-term inflammation could put patients at risk for reactivation of EBV. Determining mechanisms by which viruses can cause inflammation and finding treatments for reducing that inflammation may help reduce the disease burden for patients suffering from PASC, MS, and EBV diseases.

COVID-19: Findings in nuclear medicine from head to toe

COVID-19 is a multisystemic disease, and hence its potential manifestations on nuclear medicine imaging can extend beyond the lung. Therefore, it is important for the nuclear medicine physician to recognize these manifestations in the clinic. While FDG-PET/CT is not indicated routinely in COVID-19 evaluation, its unique capability to provide a functional and anatomical assessment of the entire body means that it can be a powerful tool to monitor acute, subacute, and long-term effects of COVID-19. Single-photon scintigraphy is routinely used to assess conditions such as pulmonary embolism, cardiac ischemia, and thyroiditis, and COVID-19 may present in these studies. The most common nuclear imaging finding of COVID-19 vaccination to date is hypermetabolic axillary lymphadenopathy. This may pose important diagnostic and management dilemmas in oncologic patients, particularly those with malignancies where the axilla constitutes a lymphatic drainage area. This article aims to summarize the relevant literature published since the beginning of the pandemic on the intersection between COVID-19 and nuclear medicine.

Detection of Post-COVID-19 Lung Abnormalities: Photon-counting CT versus Same-Day Energy-integrating Detector CT

Background Photon-counting detector (PCD) CT enables ultra-high-resolution lung imaging and may shed light on morphologic correlates of persistent symptoms after COVID-19. Purpose To compare PCD CT with energy-integrating detector (EID) CT for noninvasive assessment of post-COVID-19 lung abnormalities. Materials and Methods For this prospective study, adult participants with one or more COVID-19-related persisting symptoms (resting or exertional dyspnea, cough, fatigue) underwent same-day EID and PCD CT between April 2022 and June 2022. The 1.0-mm EID CT images and, subsequently, 1.0-, 0.4-, and 0.2-mm PCD CT images were reviewed for the presence of lung abnormalities. Subjective and objective EID and PCD CT image quality were evaluated using a five-point Likert scale (-2 to 2) and lung signal-to-noise ratios (SNRs). Results Twenty participants (mean age, 54 years ± 16 [SD]; 10 men) were included. EID CT showed post-COVID-19 lung abnormalities in 15 of 20 (75%) participants, with a median involvement of 10% of lung volume [IQR, 0%-45%] and 3.5 lobes [IQR, 0-5]. Ground-glass opacities and linear bands (10 of 20 participants [50%] for both) were the most frequent findings at EID CT. PCD CT revealed additional lung abnormalities in 10 of 20 (50%) participants, with the most common being bronchiectasis (10 of 20 [50%]). Subjective image quality was improved for 1.0-mm PCD versus 1.0-mm EID CT images (median, 1; IQR, 1-2; P < .001) and 0.4-mm versus 1.0-mm PCD CT images (median, 1; IQR, 1-1; P < .001) but not for 0.4-mm versus 0.2-mm PCD CT images (median, 0; IQR, 0-0.5; P = .26). PCD CT delivered higher lung SNR versus EID CT for 1.0-mm images (mean difference, 0.53 ± 0.96; P = .03) but lower SNR for 0.4-mm versus 1.0-mm images and 0.2-mm vs 0.4-mm images (-1.52 ± 0.68 [P < .001] and -1.15 ± 0.43 [P < .001], respectively). Conclusion Photon-counting detector CT outperformed energy-integrating detector CT in the visualization of subtle post-COVID-19 lung abnormalities and image quality. © RSNA, 2023 Supplemental material is available for this article.

Lowered oxygen saturation and increased body temperature in acute COVID-19 largely predict chronic fatigue syndrome and affective symptoms due to Long COVID: A precision nomothetic approach

BACKGROUND

Long coronavirus disease 2019 (LC) is a chronic sequel of acute COVID-19. The exact pathophysiology of the affective, chronic fatigue and physiosomatic symptoms (labelled as "physio-affective phenome") of LC has remained elusive.

OBJECTIVE

The current study aims to delineate the effects of oxygen saturation (SpO2) and body temperature during the acute phase on the physio-affective phenome of LC.

METHOD

We recruited 120 LC patients and 36 controls. For all participants, we assessed the lowest SpO2 and peak body temperature during acute COVID-19, and the Hamilton Depression and Anxiety Rating Scale (HAMD/HAMA) and Fibro Fatigue (FF) scales 3-4 months later.

RESULTS

Lowered SpO2 and increased body temperature during the acute phase and female sex predict 60.7% of the variance in the physio-affective phenome of LC. Using unsupervised learning techniques, we were able to delineate a new endophenotype class, which comprises around 26.7% of the LC patients and is characterised by very low SpO2 and very high body temperature, and depression, anxiety, chronic fatigue, and autonomic and gastro-intestinal symptoms scores. Single latent vectors could be extracted from both biomarkers, depression, anxiety and FF symptoms or from both biomarkers, insomnia, chronic fatigue, gastro-intestinal and autonomic symptoms.

CONCLUSION

The newly constructed endophenotype class and pathway phenotypes indicate that the physio-affective phenome of LC is at least in part the consequence of the pathophysiology of acute COVID-19, namely the combined effects of lowered SpO2, increased body temperature and the associated immune-inflammatory processes and lung lesions.

Update on the effectiveness of COVID-19 vaccines on different variants of SARS-CoV-2

It has been more than three years since the first emergence of coronavirus disease 2019 (COVID-19) and millions of lives have been taken to date. Like most pandemics caused by viral infections, massive public vaccination is the most promising approach to cease COVID-19 infection. In this regard, several vaccine platforms including inactivated virus, nucleic acid-based (mRNA and DNA vaccines), adenovirus-based, and protein-based vaccines have been designed and developed for COVID-19 prevention and many of them have received FDA or WHO approval. Fortunately, after global vaccination, the transmission rate, disease severity, and mortality rate of COVID-19 infection have diminished significantly. However, a rapid increase in COVID-19 cases due to the omicron variant in vaccinated countries has raised concerns about the effectiveness of these vaccines. In this review, articles published between January 2020 and January 2023 were reviewed using PubMed, Google Scholar, and Web of Science search engines with appropriate related keywords. The related papers were selected and discussed in detail. The current review mainly focuses on the effectiveness and safety of COVID-19 vaccines against SARS-CoV-2 variants. Along with discussing the available and approved vaccines, characteristics of different variants of COVID-19 have also been discussed in brief. Finally, the currently circulating COVID-19 variant i.e Omicron, along with the effectiveness of available COVID-19 vaccines against these new variants are discussed in detail. In conclusion, based on the available data, administration of newly developed bivalent mRNA COVID-19 vaccines, as booster shots, would be crucial to prevent further circulation of the newly developed variants.

New insights for infection mechanism and potential targets of COVID-19: Three Chinese patent medicines and three Chinese medicine formulas as promising therapeutic approaches

The coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with high pathogenicity and infectiousness has become a sudden and lethal pandemic worldwide. Currently, there is no accepted specific drug for COVID-19 treatment. Therefore, it is extremely urgent to clarify the pathogenic mechanism and develop effective therapies for patients with COVID-19. According to several reliable reports from China, traditional Chinese medicine (TCM), especially for three Chinese patent medicines and three Chinese medicine formulas, has been demonstrated to effectively alleviate the symptoms of COVID-19 either used alone or in combination with Western medicines. In this review, we systematically summarized and analyzed the pathogenesis of COVID-19, the detailed clinical practice, active ingredients investigation, network pharmacology prediction and underlying mechanism verification of three Chinese patent medicines and three Chinese medicine formulas in the COVID-19 combat. Additionally, we summarized some promising and high-frequency drugs of these prescriptions and discussed their regulatory mechanism, which provides guidance for the development of new drugs against COVID-19. Collectively, by addressing critical challenges, for example, unclear targets and complicated active ingredients of these medicines and formulas, we believe that TCM will represent promising and efficient strategies for curing COVID-19 and related pandemics.

Post-COVID Syndrome and Cardiorespiratory Fitness—26-Month Experience of Single Center

Introduction: Persistent post-COVID syndrome, also referred to as long COVID, is a pathologic entity that involves persistent physical, medical, and cognitive sequelae following COVID-19. Decreased fitness has repeatedly been reported in numerous studies dealing with post-COVID syndrome, however, it is still not fully clear which groups of patients may be more susceptible for persisting symptoms. Aim: The aim of our study was to evaluate the number of post-COVID patients with cardiac symptoms, where these patients were evaluated by CPET and the results compared with a control group of patients. Methods: Follow-up of patients in post-COVID outpatient clinic from 1 March 2020 to 31 May 2022. Inclusion criteria were positive PCR test for SARS-CoV-2 and age 18–100. The initial examination was performed 4–12 weeks after the disease onset. All patients with possible cardiac symptoms had completed cardiopulmonary exercise testing. The control group was randomly selected from a database of clients in 2019, with the preventive reason for evaluation. Results: From 1 March 2020 to 31 May 2022, 2732 patients (45.7% males) were evaluated with a mean age of 54.6 ± 14.7. CPET was indicated only in 97 patients (3.5%). Seventy-four patients (26 male) achieved the exercise maximum and a comparison were made with a control group (same age (p = 0.801), BMI (p = 0.721), and sex ratio). No significant dependence between the parameter VO2 max mL/kg/min and post-COVID disability was demonstrated (p = 0.412). Spearman’s correlation analysis did not show a significant relationship between the parameter VO2 max mL/kg/min and the severity of COVID-19 (p = 0.285). Conclusions: Cardiac symptoms occurred in only a small percentage of patients in our study. There is a need for further studies that would objectively evaluate the effect of COVID-19 disease on the patient’s health.

Lung Transplantation for Coronavirus Disease-2019 Patients and Coronavirus Disease-2019 in Lung Transplant Recipients

Lung transplant is a life-saving treatment for carefully selected patients with respiratory failure related to the infection with coronavirus disease-2019. Despite a complex pretransplant medical course, the posttransplant outcomes are excellent when performed by experienced centers.

Clinical and radiological outcomes of longCOVID: Is the post-COVID fibrosis common?

Introduction

COVID-19 survivors may take longer to regain full well-being. This study aimed to investigate clinical and functional evaluation and radiologic changes in the third month after COVID-19.

Materials and Methods

A total of 126 patients were assessed in the third month for symptoms, pulmonary function, exercise capacity, radiologic imaging, and quality of life after being discharged following COVID-19 treatment. Two radiologists evaluated the initial and follow-up images.

Result

At the third month follow-up visit, the most common persisting symptoms were shortness of breath (32.5%), cough (12.7%), and muscle pain (12.7%). At the follow-up visit, oxygen saturations at rest and after a sixmin walking test were lower in patients with prior intensive care hospitalization compared to those without (p<0.001, p= 0.004). Computed tomography (CT) scans revealed persisting pulmonary pathologies in 64.6% of patients at the third month follow-up. The most common pathologies on follow-up thoracic CT were fibrotic-like changes in 44.2% and ground-glass opacities (GGO) in 33.3%. Regression analysis unveiled that age [95% confidence interval (CI), 1.01 to 1.15; p= 0.020], male sex (95% CI, 4.06 to 95.3, p<0.001), first CT severity score (95% CI, 1.02 to 1.41, p= 0.028), duration of hospitalization (95% CI, 1.02 to 1.18, p= 0.012), oxygen saturation (95% CI, 0.86 to 0.96, p<0.001) were independent predictors of fibrotic-like changes.

Conclusions

In the third month following COVID-19, the most common symptom was dyspnea, and the most common radiological findings were fibrotic-like changes and GGO. Longer follow-up studies of COVID-19 survivors are needed to observe lasting changes.

Impact of COVID-19 pneumonia on interstitial lung disease: semi-quantitative evaluation with computed tomography

OBJECTIVES

To evaluate the CT scores and fibrotic pattern changes in interstitial lung disease (ILD) patients, with and without previous COVID-19 pneumonia.

METHODS

Patients with ILD (idiopathic pulmonary fibrosis (IPF) and connective tissue disease-associated ILD (CTD-ILD)) were retrospectively enrolled in the study which consisted of patients who had COVID-19 pneumonia while the control group had not. All patients had two CT scans, initial and follow-up, which were evaluated semi-quantitatively for severity, extent, and total CT scores, fibrosis patterns, and traction bronchiectasis.

RESULTS

A total of 102 patients (pneumonia group n = 48; control group n = 54) were enrolled in the study. For both groups, baseline characteristics were similar and CT scores were increased. While there was a 4.5 ± 4.6 point change in the total CT score of the COVID-19 group, there was a 1.2 ± 2.7 point change in the control group (p < 0.001). In the IPF subgroup, the change in total CT score was 7.0 points (95% CI: 4.1 to 9.9) in the COVID-19 group and 2.1 points (95% CI: 0.8 to 3.4) in the control group. Seven patients (14.6%) in the COVID-19 group progressed to a higher fibrosis pattern, but none in the control group.

CONCLUSIONS

Semi-quantitative chest CT scores in ILD patients demonstrated a significant increase after having COVID-19 pneumonia compared to ILD patients who had not had COVID-19 pneumonia. The increase in CT scores was more prominent in the IPF subgroup. There was also a worsening in the fibrosis pattern in the COVID-19 group.

KEY POINTS

• The impact of COVID-19 pneumonia on existing interstitial lung diseases and fibrosis is unclear. • COVID-19 pneumonia may worsen existing interstitial lung involvement with direct lung damage and indirect inflammatory effect. • COVID-19 pneumonia may affect existing lung fibrosis by triggering inflammatory pathways.

Post-Acute COVID-19 Syndrome: 129Xe MRI Ventilation Defects and Respiratory Outcomes One Year Later

Background In people with post-acute COVID-19 syndrome (PACS) and normal pulmonary function, ¹²⁹Xe MRI ventilation defects, abnormal quality-of-life scores, and exercise limitation were reported 3-months after infection; the longitudinal trajectory remains unclear. Purpose To measure and compare pulmonary function, exercise capacity, quality-of-life, and ¹²⁹Xe MRI ventilation defect percent (VDP) in people with PACS evaluated 3- and 15-months post-infection. Materials and Methods In this prospective study, participants with PACS aged 18-80 years were enrolled between July 2020 and August 2021 from two quaternary care centers. They were evaluated 3-months and 15-months post-infection for: ¹²⁹Xe MRI VDP, diffusing capacity of the lung for carbon monoxide (DL_CO), spirometry, oscillometry, six-minute walk distance (6MWD), and St. George's Respiratory Questionnaire (SGRQ). Differences between time-points were evaluated using paired t-tests. Multivariable models were generated to explain exercise capacity and quality-of-life improvements. Odds ratios (OR) were used to evaluate potential treatment influences. Results Fifty-three participants (mean age, 55 years ±18[SD]; 26 male; 27 female) attended both 3- and 15-month visits and were included in analysis. ¹²⁹Xe MRI VDP (5.4%, 4.2%; P=.003), forced expiratory volume in 1-second (85%_pred, 90%_pred; P=.001), DL_CO (89%_pred, 99%_pred; P=.002) and SGRQ (35, 25; P<.001) improved between the 3- and 15-month visit. VDP measured at 3- months post-COVID predicted the change in 6MWD (β=-.643, P=.001) while treatment with respiratory medication at 3-months predicted improved 15-month quality-of-life score (OR=4.0; 95%CI:1.2,13.8, P=.03). Conclusion Pulmonary function, gas-exchange, exercise capacity, quality-of-life, and ¹²⁹Xe MRI ventilation defect percent (VDP) improved in participants with post-acute COVID-19 syndrome evaluated at 15-months as compared to 3-months post-infection. VDP measured at 3-months post-infection correlated with improved exercise capacity, whilst treatment with respiratory medication was associated with improved quality-of-life score at 15-months post-infection. Clinical Trial Registration: www.clinicaltrials.gov NCT05014516 See also the editorial by Vogel-Claussen in this issue.

Chest computed tomography findings of the Omicron variants of SARS-CoV-2 with different cycle threshold values

BACKGROUND

The Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mainly infects the upper respiratory tract. This study aimed to determine whether the probability of pulmonary infection and the cycle threshold (Ct) measured using the fluorescent polymerase chain reaction (PCR) method were related to pulmonary infections diagnosed via computed tomography (CT).

AIM

To analyze the chest CT signs of SARS-CoV-2 Omicron variant infections with different Ct values, as determined via PCR.

METHODS

The chest CT images and PCR Ct values of 331 patients with SARS-CoV-2 Omicron variant infections were retrospectively collected and categorized into low (< 25), medium (25.00-34.99), and high (≥ 35) Ct groups. The characteristics of chest CT images in each group were statistically analyzed.

RESULTS

The PCR Ct values ranged from 13.36 to 39.81, with 99 patients in the low, 155 in the medium, and 77 in the high Ct groups. Six abnormal chest CT signs were detected, namely, focal infection, patchy consolidation shadows, patchy ground-glass shadows, mixed consolidation ground-glass shadows, subpleural interstitial changes, and pleural changes. Focal infections were less frequent in the low Ct group than in the medium and high Ct groups; these infections were the most common sign in the medium and high Ct groups. Patchy consolidation shadows and pleural changes were more frequent in the low Ct group than in the other two groups. The number of patients with two or more signs was greater in the low Ct group than in the medium and high Ct groups.

CONCLUSION

The chest CT signs of patients with pulmonary infection caused by the Omicron variants of SARS-CoV-2 varied depending on the Ct values. Identification of the characteristics of Omicron variant infection can help subsequent planning of clinical treatment.

Identification and Follow-up of COVID-19 Related Matching Ventilation and Perfusion Defects on Functional Imaging Using VQ SPECT/CT

Purpose

Available clinical data have revealed that coronavirus disease 2019 (COVID-19) is associated with a risk of pulmonary microthrombosis and small airway disease. These patients present with varying degrees of perfusion abnormalities. The purpose of this study was to evaluate the use of a ventilation/perfusion single-photon emission computed tomography/computed tomography (VQ SPECT/CT) in the detection and follow-up of persistent lung perfusion abnormalities that were suspected to be due to pulmonary microthrombosis, small airway disease, or both.

Methods

A retrospective study was conducted at the department of nuclear medicine of Universitas Academic Hospital in Bloemfontein, South Africa. We reviewed the studies of 78 non-hospitalized patients with COVID-19 infection referred to our department from July 2020 to June 2021 for a perfusion only SPECT/CT study or a VQ SPECT/CT study. Pulmonary embolism was suspected in all 78 cases.

Results

Seventy-eight patients were studied. The median (interquartile range) age was 45 (41-58) years, and the majority (n = 69; 88.5%) were females. Twenty-two (28.2%) of these patients had matching VQ defects with mosaic attenuation on CT. All nine of the patients who had follow-up studies had these abnormalities persistently, even after 1 year.

Conclusion

We confirm that the VQ scan is a safe and effective tool to identify and follow-up recovered COVID-19 patients with persistent ventilation and perfusion abnormalities suspicious of small airway disease and pulmonary microthrombosis.