Differential diagnoses of acute ground-glass opacity in chest computed tomography: pictorial essay.

Ground-glass opacity is a very frequent and unspecified finding in chest computed tomography. Therefore, it admits a wide range of differential diagnoses in the acute context, from viral pneumonias such as influenza virus, coronavirus disease 2019 and cytomegalovirus and even non-infectious lesions, such as vaping, pulmonary infarction, alveolar hemorrhage and pulmonary edema. For this diagnostic differentiation, ground glass must be correlated with other findings in imaging tests, with laboratory tests and with the patients' clinical condition. In the context of a pandemic, it is extremely important to remember the other pathologies with similar findings to coronavirus disease 2019 in the imaging exams.

Differential diagnoses of acute ground-glass opacity in chest computed tomography: pictorial essay / Diagnósticos diferenciais de opacidade em vidro fosco aguda na tomografia computadorizada de tórax: ensaio pictórico

ABSTRACT Ground-glass opacity is a very frequent and unspecified finding in chest computed tomography. Therefore, it admits a wide range of differential diagnoses in the acute context, from viral pneumonias such as influenza virus, coronavirus disease 2019 and cytomegalovirus and even non-infectious lesions, such as vaping, pulmonary infarction, alveolar hemorrhage and pulmonary edema. For this diagnostic differentiation, ground glass must be correlated with other findings in imaging tests, with laboratory tests and with the patients' clinical condition. In the context of a pandemic, it is extremely important to remember the other pathologies with similar findings to coronavirus disease 2019 in the imaging exams.

RESUMO A opacidade em vidro fosco é uma alteração muito frequente e pouco específica na tomografia computadorizada de tórax. Ela admite grande leque de diagnósticos diferenciais no contexto agudo, desde pneumonias virais, como as causadas pelo vírus influenza, pela doença do coronavírus 2019 e pelo citomegalovírus, até mesmo lesões de origem não infecciosa, como vaping , infarto pulmonar, hemorragia alveolar e edema pulmonar. Para essa diferenciação diagnóstica, deve-se correlacionar o vidro fosco com os demais achados nos exames de imagem, exames laboratoriais e quadro clínico do paciente. É de suma importância, no contexto de pandemia, recordar as demais patologias com os achados semelhantes aos da doença do coronavírus 2019 nos exames de imagem.

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.

High-resolution computed tomography enhances the diagnosis and follow-up of influenza A (H1N1) virus-associated pneumonia.

INTRODUCTION: We present the findings on high-resolution computed tomography (HRCT) of influenza A (H1N1) virus-associated pneumonia of 140 patients with acute and post-acute pneumonia, totaling 189 exams in a retrospective observational study evaluating the importance of HRCT as a diagnostic imaging method in the acute phase and in the follow-up of pneumonia. METHODOLOGY: We performed a retrospective observational study evaluating the HRCT findings of 140 adult patients with confirmed diagnosis of influenza A (H1N1) pneumonia and without other associated infectious processes. Chest X-ray exams were also performed in these patients. RESULTS: The main HRCT findings of lung involvement were airspace consolidation (57 cases), ground-glass opacities (40 cases) and an association of both aspects (43 cases), with a predominantly bilateral and peripheral distribution. CONCLUSIONS: HRCT is able to distinguish small lesions, such as small areas of consolidation or ground glass opacities, with little increase in lung attenuation, when chest X-rays was normal, allowing a prompt diagnosis and treatment after imaging.

Influenza A (H1N1) pneumonia: HRCT findings.

OBJECTIVE: To describe aspects found on HRCT scans of the chest in patients infected with the influenza A (H1N1) virus. METHODS: We retrospectively analyzed the HRCT scans of 71 patients (38 females and 33 males) with H1N1 infection, confirmed through laboratory tests, between July and September of 2009. The HRCT scans were interpreted by two thoracic radiologists independently, and in case of disagreement, the decisions were made by consensus. RESULTS: The most common HRCT findings were ground-glass opacities (85%), consolidation (64%), or a combination of ground-glass opacities and consolidation (58%). Other findings were airspace nodules (25%), bronchial wall thickening (25%), interlobular septal thickening (21%), crazy-paving pattern (15%), perilobular pattern (3%), and air trapping (3%). The findings were frequently bilateral (89%), with a random distribution (68%). Pleural effusion, when observed, was typically minimal. No lymphadenopathy was identified. CONCLUSIONS: The most common findings were ground-glass opacities and consolidations, or a combination of both. Involvement was commonly bilateral with no axial or craniocaudal predominance in the distribution. Although the major tomographic findings in H1N1 infection are nonspecific, it is important to recognize such findings in order to include infection with the H1N1 virus in the differential diagnosis of respiratory symptoms.

Chest computed tomography findings in severe influenza pneumonia occurring in neutropenic cancer patients.

OBJECTIVE: To describe the chest computed tomography findings for severe influenza H1N1 infection in a series of hospitalized neutropenic cancer patients. METHODS: We performed a retrospective systematic analysis of chest computed tomography scans for eight hospitalized patients with fever, neutropenia, and confirmed diagnoses of influenza H1N1. The clinical data had been prospectively collected. RESULTS: Six of eight patients (75%) developed respiratory failure and required intensive care. Prolonged H1N1 shedding was observed in the three mechanically ventilated patients, and overall hospital mortality in our series was 25%. The most frequent computed tomography findings were ground-glass opacity (all patients), consolidation (7/8 cases), and airspace nodules (6/8 cases) that were frequently moderate or severe. Other parenchymal findings were not common. Five patients had features of pneumonia, two had computed tomography findings compatible with bronchitis and/or bronchiolitis, and one had tomographic signs of chronicity. CONCLUSION: In this series of neutropenic patients with severe influenza H1N1 infection, chest computed tomography demonstrated mainly moderate or severe parenchymatous disease, but bronchiolitis was not a common feature. These findings associated with febrile neutropenia should elicit a diagnosis of severe viral infection.

Swine-origin influenza A (H1N1) viral infection: thoracic findings on CT.

OBJECTIVE: The purpose of this article is to illustrate and describe various CT manifestations of swine-origin influenza A (H1N1) viral infection. CONCLUSION: The imaging findings seen in patients with H1N1 infection include consolidations, ground-glass opacities, interlobular septal thickening, small nodules, and findings suggestive of small airways disease, among others. Definitive diagnosis is based on correlation of the CT findings with the clinical symptoms and laboratory test results.

[Influenza A H1N1 respiratory infection: radiologic findings and correlation with clinical outcome in pediatric inpatients. A pediatric hospital experience]. / Infección respiratoria por influenza A H1N1 en niños: Hallazgos radiológicos y correlación con el pronóstico clínico en pacientes internados en un hospital pediátrico.

INTRODUCTION: In the year 2009, the World Health Organization declared the Influenza A H1N1 virus as a pandemic. It has been reported that the radiographic pattern in chest x-ray may predict the clinical outcome in patients affected. OBJECTIVE: To describe the chest x-ray findings in pediatrics patients with confirmed diagnosis of Influenza H1N1 respiratory infection and its correlation with clinical evolution. POPULATION AND METHODS: A retrospective, analytic and descriptive study of 47 pediatric inpatients with confirmed diagnosis of H1N1 influenza who had available chest x-ray was performed. Medical records were reviewed for underlying medical conditions and patient's outcome. RESULTS: 94% of patients had abnormal x-ray. Consolidation and ground-glass opacities had significantly higher frequency in patients who needed more days of oxygen supplement. Initial chest x-ray with lobar consolidation was observed in patients with greater risk of Intensive care unit admission. CONCLUSION: The most frequent radiological patterns found were ground-glass opacities and peribronchial markings. Lobar consolidation and ground-glass opacities are associated with adverse outcome.

Hospital triage system for adult patients using an influenza-like illness scoring system during the 2009 pandemic--Mexico.

BACKGROUND: Pandemic influenza A (H1N1) virus emerged during 2009. To help clinicians triage adults with acute respiratory illness, a scoring system for influenza-like illness (ILI) was implemented at Hospital Civil de Guadalajara, Mexico. METHODS: A medical history, laboratory and radiology results were collected on emergency room (ER) patients with acute respiratory illness to calculate an ILI-score. Patients were evaluated for admission by their ILI-score and clinicians' assessment of risk for developing complications. Nasal and throat swabs were collected from intermediate and high-risk patients for influenza testing by RT-PCR. The disposition and ILI-score of those oseltamivir-treated versus untreated, clinical characteristics of 2009 pandemic influenza A (H1N1) patients versus test-negative patients were compared by Pearson's Chi(2), Fisher's Exact, and Wilcoxon rank-sum tests. RESULTS: Of 1840 ER patients, 230 were initially hospitalized (mean ILI-score = 15), and the rest were discharged, including 286 ambulatory patients given oseltamivir (median ILI-score = 11), and 1324 untreated (median ILI-score = 5). Fourteen (1%) untreated patients returned, and 3 were hospitalized on oseltamivir (median ILI-score = 19). Of 371 patients tested by RT-PCR, 104 (28%) had pandemic influenza and 42 (11%) had seasonal influenza A detected. Twenty (91%) of 22 imaged hospitalized pandemic influenza patients had bilateral infiltrates compared to 23 (38%) of 61 imaged hospital test-negative patients (p<0.001). One patient with confirmed pandemic influenza presented 6 days after symptom onset, required mechanical ventilation, and died. CONCLUSIONS: The triaging system that used an ILI-score complimented clinicians' judgment of who needed oseltamivir and inpatient care and helped hospital staff manage a surge in demand for services.

High-resolution computed tomography findings from adult patients with Influenza A (H1N1) virus-associated pneumonia.

OBJECTIVE: The aim of this study was to assess the high-resolution computed tomography (HRCT) findings at presentation in patients diagnosed with Influenza A (H1N1) virus-associated pneumonia. MATERIALS AND METHODS: We reviewed the HRCT findings from 20 patients diagnosed with Influenza A (H1N1) and compared their HRCT scans with chest radiographs, obtained on the same day. The imaging studies were obtained 4-9 days after the onset of symptoms. The patients included 11 men and 9 women (ages 24-62 years; mean 42.7 years). All patients had a body temperature greater than 100.4 degrees F (>38 degrees C), tachypnea, and cough. Other common symptoms included diarrhea (60%) and sore throat (30%). The radiographs and HRCT scans were reviewed independently by two observers who reached a consensus decision. RESULTS: The predominant HRCT findings consisted of bilateral ground-glass opacities (n=12), bilateral areas of consolidation (n=2), or a mixed bilateral pattern of ground-glass opacities and areas of consolidation (n=6). The abnormalities were bilateral in all of the 20 patients, had a predominantly sub-pleural distribution in 13 patients, and had a random distribution in the remaining 7 patients. The predominant radiographic findings were consolidations. Normal radiographs were found in 4 out of the 20 patients. CONCLUSION: HRCT may reveal parenchymal abnormalities in patients with Influenza A (H1N1) infection who have normal findings on radiographs. The predominant HRCT findings were bilateral, peripheral, ground-glass opacities and/or bilateral areas of consolidation. The patients who presented consolidations had more severe clinical course.

[Influenza B virus pneumonia after bone marrow transplantation: case report with emphasis to the high resolution computed tomography findings]. / Pneumonia pelo vírus influenza B pós-transplante de medula óssea: relato de caso com ênfase dos achados de tomografia computadorizada de alta resolução.

Nine year-old male patient, who underwent bone marrow transplantation because of acute myelogenous leukemia, presented with fever and dry cough three days after the procedure. The chest radiograph demonstrated bilateral diffuse reticular infiltrate. The high resolution computed tomography showed peribronchovascular interstitial thickening, peripheral small centrilobular nodules and areas of ground-glass attenuation. The bronchoalveolar lavage demonstrated positive direct fluorescence antibody testing against influenza B virus. Treatment with aerolizated ribavirin was instituted during 10 days and the patient showed clinical-radiological improvement.