Novel influenza A (H1N1) infection: chest CT findings from 21 cases in Seoul, Korea

A case report of pneumomediastinum in a COVID-19 patient treated with high-flow nasal cannula and review of the literature: Is this a "spontaneous" complication?

Oxygen support with high-flow nasal cannula (HFNC) is gentler than mechanical ventilation and may provide significant benefits, but more studies are needed to investigate the efficacy and safety of different respiratory supports in patients with COVID-19 pneumonia.

A Comparative Systematic Review of COVID-19 and Influenza

Background: Both SARS-CoV-2 and influenza virus share similarities such as clinical features and outcome, laboratory, and radiological findings. Methods: Literature search was done using PubMed to find MEDLINE indexed articles relevant to this study. As of 25 November 2020, the search has been conducted by combining the MeSH words “COVID-19” and “Influenza”. Results: Eighteen articles were finally selected in adult patients. Comorbidities such as cardiovascular diseases, diabetes, and obesity were significantly higher in COVID-19 patients, while pulmonary diseases and immunocompromised conditions were significantly more common in influenza patients. The incidence rates of fever, vomiting, ocular and otorhinolaryngological symptoms were found to be significantly higher in influenza patients when compared with COVID-19 patients. However, neurologic symptoms and diarrhea were statistically more frequent in COVID-19 patients. The level of white cell count and procalcitonin was significantly higher in influenza patients, whereas thrombopenia and elevated transaminases were significantly more common in COVID-19 patients. Ground-grass opacities, interlobular septal thickening, and a peripheral distribution were more common in COVID-19 patients than in influenza patients where consolidations and linear opacities were described instead. COVID-19 patients were significantly more often transferred to intensive care unit with a higher rate of mortality. Conclusions: This study estimated differences of COVID-19 and influenza patients which can help clinicians during the co-circulation of the two viruses.

Chest Computed Tomography Findings in COVID-19 and Influenza: A Narrative Review

Objective

The COVID-19 pandemic and annual influenza epidemic are responsible for thousands of deaths globally. With a similarity in clinical as well as laboratory findings, there is a need to differentiate these two conditions on chest CT scan. This paper attempts to use existing literature to draw out differences in chest CT findings in COVID-19 and influenza.

Methods

A search was conducted using PubMed. 17 original studies on chest CT findings in COVID-19 and influenza were identified for full-text review and data analysis. Findings. COVID-19 and influenza share similar chest CT findings. The differences found show that COVID-19 ground-glass opacities are usually peripherally located with the lower lobes being commonly involved, while influenza has a central, peripheral, or random distribution usually affecting the five lobes. Vascular engorgement, pleural thickening, and subpleural lines were reported in COVID-19 patients. In contrast, pneumomediastinum and pneumothorax were reported only in studies on influenza. Conclusion and Relevance. COVID-19 and influenza have overlapping chest CT features with few differences which can assist in telling apart the two pathologies. Additional studies are needed to further define the differences and degree between COVID-19 and influenza.

Planning and coordination of the radiological response to the coronavirus disease 2019 (COVID-19) pandemic: the Singapore experience. Clin Radiol. 2020;75:415-422. [PMID: 32291080 PMCID: PMC7151533 DOI: 10.1016/j.crad.2020.03.028]

Coronavirus disease 2019 (COVID-19) has spread fast and extensively around the world, with significant mortality and morbidity. As this is a respiratory infection, chest radiography and computed tomography (CT) are important imaging techniques in the work-up of this disease. Given its highly infectious nature, cross-infection within the healthcare setting and radiology departments needs to be addressed actively and prevented. We describe the response of radiology departments in Singapore to this pandemic, in terms of diagnosis, re-configuration of the department, re-organisation and segregation of staff, infection control, managerial, and leadership issues.

A retrospective study of the initial chest CT imaging findings in 50 COVID-19 patients stratified by gender and age

OBJECTIVE

To retrospectively analyze and stratify the initial clinical features and chest CT imaging findings of patients with COVID-19 by gender and age.

METHODS

Data of 50 COVID-19 patients were collected in two hospitals. The clinical manifestations, laboratory examination and chest CT imaging features were analyzed, and a stratification analysis was performed according to gender and age [younger group: <50 years old, elderly group ≥50 years old].

RESULTS

Most patients had a history of epidemic exposure within 2 weeks (96%). The main clinical complaints are fever (54%) and cough (46%). In chest CT images, ground-glass opacity (GGO) is the most common feature (37/38, 97%) in abnormal CT findings, with the remaining 12 patients (12/50, 24%) presenting normal CT images. Other concomitant abnormalities include dilatation of vessels in lesion (76%), interlobular thickening (47%), adjacent pleural thickening (37%), focal consolidation (26%), nodules (16%) and honeycomb pattern (13%). The lesions were distributed in the periphery (50%) or mixed (50%). Subgroup analysis showed that there was no difference in the gender distribution of all the clinical and imaging features. Laboratory findings, interlobular thickening, honeycomb pattern and nodules demonstrated remarkable difference between younger group and elderly group. The average CT score for pulmonary involvement degree was 5.0±4.7. Correlation analysis revealed that CT score was significantly correlated with age, body temperature and days from illness onset (p < 0.05).

CONCLUSIONS

COVID-19 has various clinical and imaging appearances. However, it has certain characteristics that can be stratified. CT plays an important role in disease diagnosis and early intervention.

The CT appearance of lower respiratory infection due to parainfluenza virus in adults

OBJECTIVE

We retrospectively reviewed the CT findings of lower respiratory tract infection (LRTI) due to parainfluenza virus (PIV) to determine the imaging features of PIV infection and to identify any differences compared with the CT appearances of LRTIs due to respiratory syncytial virus (RSV), adenovirus, and influenza virus.

MATERIALS AND METHODS

The imaging features of LRTI from PIV over a 51-month period were retrospectively reviewed. The specific CT findings and overall pattern of infection in patients with LRTI due to PIV were recorded and were then compared with the CT appearances of RSV, adenovirus, and influenza LRTIs using data from a previous study.

RESULTS

Twenty-four chest CT examinations of 24 patients with PIV infection were analyzed. Tree-in-bud opacities were the most common finding (13/24, 54%), and the airway-centric pattern of disease--characterized by combinations of bronchial wall thickening, tree-in-bud opacities, and peribronchiolar consolidation (bronchitis, bronchiolitis, and bronchopneumonia)--was the most common pattern (16/24, 67%). In comparison with previous data on RSV, adenovirus, and influenza virus, PIV showed tree-in-bud opacities and airway-centric patterns significantly more often than adenovirus or influenza virus. PIV and RSV showed similar CT findings and patterns of disease.

CONCLUSION

Despite varying CT appearances of PIV LRTI, it most often shows airway-centric disease and is similar to the appearance of RSV infection, both of which are members of the Paramyxoviridae family of viruses.

Viral diseases affecting the pleura

BACKGROUND

Viruses affect the human body in multiple ways producing various disease states. The infections of the pulmonary parenchyma have been well described. However, there has been no current review of the literature pertaining to the pleura.

AIM

To review the available literature pertaining to diseases of the pleura that are caused by viral infections.

METHODS

A Medline search was performed and available research and review articles relating to viral infections that resulted in pleural effusions, pleural masses, pleural thickening, and pleural nodularity were reviewed.

CONCLUSION

There are numerous viruses that cause diseases of the pleura. Pleural effusions and lesions within the pleura are the most common presentation of the disease state. Polymerase chain reaction has the potential to further diagnose viral infections and expand our knowledge base in this field.

Molecular imaging reveals a progressive pulmonary inflammation in lower airways in ferrets infected with 2009 H1N1 pandemic influenza virus

Molecular imaging has gained attention as a possible approach for the study of the progression of inflammation and disease dynamics. Herein we used [(18)F]-2-deoxy-2-fluoro-D-glucose ([(18)F]-FDG) as a radiotracer for PET imaging coupled with CT (FDG-PET/CT) to gain insight into the spatiotemporal progression of the inflammatory response of ferrets infected with a clinical isolate of a pandemic influenza virus, H1N1 (H1N1pdm). The thoracic regions of mock- and H1N1pdm-infected ferrets were imaged prior to infection and at 1, 2, 3 and 6 days post-infection (DPI). On 1 DPI, FDG-PET/CT imaging revealed areas of consolidation in the right caudal lobe which corresponded with elevated [(18)F]-FDG uptake (maximum standardized uptake values (SUVMax), 4.7-7.0). By days 2 and 3, consolidation (CT) and inflammation ([(18)F]-FDG) appeared in the left caudal lobe. By 6 DPI, CT images showed extensive areas of patchy ground-glass opacities (GGO) and consolidations with the largest lesions having high SUVMax (6.0-7.6). Viral shedding and replication were detected in most nasal, throat and rectal swabs and nasal turbinates and lungs on 1, 2 and 3 DPI, but not on day 7, respectively. In conclusion, molecular imaging of infected ferrets revealed a progressive consolidation on CT with corresponding [(18)F]-FDG uptake. Strong positive correlations were measured between SUVMax and bronchiolitis-related pathologic scoring (Spearman's ρ = 0.75). Importantly, the extensive areas of patchy GGO and consolidation seen on CT in the ferret model at 6 DPI are similar to that reported for human H1N1pdm infections. In summary, these first molecular imaging studies of lower respiratory infection with H1N1pdm show that FDG-PET can give insight into the spatiotemporal progression of the inflammation in real-time.

High-resolution computed tomography findings of swine-origin influenza A (H1N1) virus (S-OIV) infection: comparison with scrub typhus

BACKGROUND

Swine-origin influenza A (H1N1) virus (S-OIV) infection and scrub typhus, also known as tsutsugamushi disease can manifest as acute respiratory illnesses, particularly during the late fall or early winter, with similar radiographic findings, such as a predominance of ground-glass opacity (GGO).

PURPOSE

To differentiate S-OIV infection from scrub typhus using high-resolution computed tomography (HRCT).

MATERIAL AND METHODS

We retrospectively reviewed the HRCT findings of 14 patients with S-OIV infection and 10 patients with scrub typhus. We assessed the location, cross-sectional distribution, and the presence of a peribronchovascular distribution of GGO and consolidations on HRCT. We also assessed the presence of interlobular septal thickening, bronchial wall thickening, pneumothorax, pneumomediastinum, pleural effusion, and mediastinal or axillary lymph node enlargement.

RESULTS

Scrub typhus was more common than S-OIV in elderly patients (P < 0.001). The monthly incidences of S-OIV and scrub typhus infection reached a peak between October and November. About 86% of S-OIV patients and 80% of scrub typhus patients presented with GGO. About 67% of the GGO lesions in S-OIV had a peribronchovascular distribution, but this was absent in scrub typhus (P = 0.005). Consolidation (93% vs. 10%, P < 0.001) and bronchial wall thickening (43% vs. 0%, P = 0.024) were more frequent in S-OIV infection than scrub typhus. Interlobular septal thickening (90% vs. 36%, P = 0.013) and axillary lymphadenopathy (90% vs. 0%, P < 0.001) were more common in scrub typhus than S-OIV infection.

CONCLUSION

There was considerable overlap in HRCT findings between S-OIV infection and scrub typhus. However, S-OIV showed a distinctive peribronchovascular distribution of GGO lesions. Consolidation and bronchial wall thickening were seen more frequently in S-OIV infection, whereas interlobular septal thickening and axillary lymphadenopathy were more common in scrub typhus. Thus, CT could be helpful for differential diagnosis between S-OIV infection and scrub typhus.

Pulmonary manifestation of novel swine-origin influenza A (H1N1) virus (S-OIV) infection in immunocompromised patients: initial findings with multidetector computed tomography

OBJECTIVE

To describe initial multidetector computed tomographic (MDCT) findings of novel swine-origin influenza A (H1N1) virus (S-OIV) infection in immunocompromised patients and to evaluate whether or not identification of certain abnormalities can help predict patients who are at risk for a severe clinical course.

SUBJECTS AND METHODS

This retrospective study included 13 patients with confirmed S-OIV infection suffering from an underlying immunodeficiency or who were receiving immunosuppressive therapy. All patients underwent MDCT of the thorax due to respiratory distress. All data were read by two independent radiologists who described the type and pattern of opacities, distribution and extent of the abnormalities observed. Adverse outcome measures were defined as acute respiratory distress syndrome with the need for mechanical ventilation, extracorporeal membrane oxygenation or death.

RESULTS

MDCT revealed pulmonary manifestations in 12 (92%) of 13 individuals. Six (50%) patients showed an adverse outcome with development of acute respiratory distress syndrome, 4 of these died. The most common findings were ground-glass opacities (10/12; 83%) and pulmonary consolidation (7/12; 58%) predominantly with a bilateral distribution. Reticular pattern and a tree-in-bud appearance were found in 3/12 (25%), respectively. Bilateral opacities with extensive involvement of the lung parenchyma were most predictive of a severe clinical course.

CONCLUSION

The MDCT scan in immunocompromised patients with confirmed S-OIV infection frequently revealed pulmonary abnormalities, which included ground-glass opacities and consolidations. Therefore, prediction of an adverse clinical outcome could be made in patients with MDCT findings demonstrating bilateral extensive consolidations, often combined with ground-glass opacities.

CT of viral lower respiratory tract infections in adults: comparison among viral organisms and between viral and bacterial infections. AJR Am J Roentgenol. 2011;197:1088-1095. [PMID: 22021500 DOI: 10.2214/ajr.11.6501]

OBJECTIVE

We retrospectively compared the CT findings of consecutive viral and bacterial lower respiratory tract infections (LRTIs) to determine their imaging appearance and any definable differences among the causative viruses and between the viral and bacterial infections.

MATERIALS AND METHODS

Imaging features of LRTI caused by influenza virus, respiratory syncytial virus (RSV), parainfluenza, adenovirus, and bacteria over a 33-month period were reviewed by three radiologists blinded to clinical and diagnostic information. Individual CT features and the dominant pattern of infection were recorded for each examination. Imaging characteristics were compared among the four respiratory viruses and between viral and bacterial infections.

RESULTS

One hundred fifteen chest CT scans were analyzed (60 influenza virus, 19 RSV, 10 adenovirus, four parainfluenza virus, and 22 bacterial pneumonia LRTIs). Individual imaging findings and imaging patterns were seen in similar frequencies when we compared viral and bacterial LRTIs, with the exception of the diffuse airspace pattern, which was seen more frequently in bacterial infections. Although there was overlap in the imaging appearance of individual viruses, RSV and adenovirus tended to have characteristic imaging appearances. RSV presented with an airway-centric pattern of disease (13/19 cases [68%]) characterized by varying mixtures of tree-in-bud opacities and bronchial wall thickening, with or without peribronchiolar consolidation. Adenovirus typically appeared as multifocal consolidation or ground-glass opacity without airway inflammatory findings (7/10 cases [70%]).

CONCLUSION

There is considerable overlap in the imaging appearance of viral and bacterial respiratory infections. However, some characteristic differences can be seen, especially with RSV and adenovirus infections.