Thin-Section CT Findings in Hematopoietic Stem Cell Transplantation Recipients with Respiratory Virus Pneumonia

Early pulmonary complications related to cancer treatment in children

In this review, we summarize early pulmonary complications related to cancer therapy in children and highlight characteristic findings on imaging that should be familiar to a radiologist reviewing imaging from pediatric cancer patients.

When Viruses Meet Fungi: Tackling the Enemies in Hematology

The association of invasive fungal infections (IFI) and viral infections has been described in patients with hematologic malignancies (HM), in particular in hematopoietic stem cell transplant recipients. Regrettably, the diagnosis is often challenging, making the treatment inappropriate in some circumstances. The present review takes into consideration the viral infections commonly associated with IFI. Clinical presentation of IFI and viral infections, risk factors, and impact on the outcome of HM patients are discussed throughout the paper.

Community-acquired Respiratory Virus Cases Mimic COVID-19 on Lung Computed Tomography

We herein report four patients with community-acquired respiratory virus (CRV) infection. Although they had no history of contact with any individual with coronavirus disease 2019 (COVID-19), they were suspected of having COVID-19 based on findings of high-resolution computed tomography (CT) of the lungs. Among the four patients, two were infected with rhinovirus, one with metapneumovirus, and one with influenza A. Their chest CT findings were similar to those of COVID-19 patients reported in previous studies. Both CRV infection and COVID-19 can show various patterns on chest CT. CRV infection is thus indistinguishable from COVID-19 based on CT findings alone.

Pulmonary Complications in Children Following Hematopoietic Cell Transplantation: A Case Report and Review of the Diagnostic Approach

Pulmonary complications are common in children following hematopoietic cell transplantation (HCT) and contribute to their morbidity and mortality. Early diagnosis is essential for management and prevention of progression of lung injury and damage. In many cases, diagnosis can be challenging and may require diagnostic imaging and more invasive testing such as bronchoscopy and lung biopsy. We report the case of a 12-year-old girl who developed recurrent episodes of acute respiratory failure requiring intensive care unit admission in the post-HCT phase and describe the diagnostic and multidisciplinary approach for her management. In addition, we review the diagnostic approach of pulmonary complications post-HCT and highlight the utility and risks of bronchoscopy and lung biopsy in these children.

Atypical Pneumonia: Definition, Causes, and Imaging Features

Pneumonia is among the most common causes of death worldwide. The epidemiologic and clinical heterogeneity of pneumonia results in challenges in diagnosis and treatment. There is inconsistency in the definition of the group of microorganisms that cause "atypical pneumonia." Nevertheless, the use of this term in the medical and radiologic literature is common. Among the causes of community-acquired pneumonia, atypical bacteria are responsible for approximately 15% of cases. Zoonotic and nonzoonotic bacteria, as well as viruses, have been considered among the causes of atypical pneumonia in a patient who is immunocompetent and have been associated with major community outbreaks of respiratory infection, with relevant implications in public health policies. Considering the difficulty of isolating atypical microorganisms and the significant overlap in clinical manifestations, a targeted empirical therapy is not possible. Imaging plays an important role in the diagnosis and management of atypical pneumonia, as in many cases its findings may first suggest the possibility of an atypical infection. Clarifying and unifying the definition of atypical pneumonia among the medical community, including radiologists, are of extreme importance. The prompt diagnosis and prevention of community spread of some atypical microorganisms can have a relevant impact on local, regional, and global health policies. ^©RSNA, 2021.

Respiratory Virus Infections of the Stem Cell Transplant Recipient and the Hematologic Malignancy Patient

Respiratory virus infections in hematologic stem cell transplant recipients and patients with hematologic malignancies are increasingly recognized as a cause of significant morbidity and mortality. The often overlapping clinical presentation makes molecular diagnostic strategies imperative for rapid diagnosis and to inform understanding of the changing epidemiology of each of the respiratory viruses. Most respiratory virus infections are managed with supportive therapy, although there is effective antiviral therapy for influenza. The primary focus should remain on primary prevention infection control procedures and isolation precautions, avoidance of ill contacts, and vaccination for influenza.

Potential role of CT-textural features for differentiation between viral interstitial pneumonias, pneumocystis jirovecii pneumonia and diffuse alveolar hemorrhage in early stages of disease: a proof of principle

Background

Pulmonary involvement is common in several infectious and non-infectious diagnostic settings. Imaging findings consistently overlap and are therefore difficult to differentiate by chest-CT. The aim of this study was to evaluate the role of CT-textural features(CTTA) for discrimination between atypical viral (respiratory-syncitial-virus(RSV) and herpes-simplex-1-virus (HSV1)), fungal (pneumocystis-jirovecii-pneumonia(PJP)) interstitial pneumonias and alveolar hemorrhage.

Methods

By retrospective single-centre analysis we identified 46 consecutive patients (29 m) with RSV(n = 5), HSV1(n = 6), PJP(n = 21) and lung hemorrhage(n = 14) who underwent unenhanced chest CTs in early stages of the disease between 01/2016 and 02/2017. All cases were confirmed by microbiologic direct analysis of bronchial lavage. On chest-CT-scans, the presence of imaging features like ground-glass opacity(GGO), crazy-paving, air-space consolidation, reticulation, bronchial wall thickening and centrilobular nodules were described. A representative large area was chosen in both lungs and used for CTTA-parameters (included heterogeneity, intensity, average, deviation, skewness).

Results

Discriminatory CTTA-features were found between alveolar hemorrhage and PJP consisting of differences in mean heterogeneity(p < 0.015) and uniformity of skewness(p < 0.006). There was no difference between CT-textural features of diffuse alveolar hemorrhage and viral pneumonia or PJP and viral pneumonia. Visual HRCT-assessment yielded great overlap of imaging findings with predominance of GGO for PJP and airspace consolidation for pneumonia/alveolar hemorrhage. Significant correlations between HRCT-based imaging findings and CT-textural features were found for all three disease groups.

Conclusion

CT-textural features showed significant differences in mean heterogeneity and uniformity of skewness. HRCT-based imaging findings correlated with certain CT-textural features showing that the latter have the potential to characterize structural properties of lung parenchyma and related abnormalities.

Electronic supplementary material

The online version of this article (10.1186/s12880-019-0338-0) contains supplementary material, which is available to authorized users.

Respiratory Virus Infections in Hematopoietic Cell Transplant Recipients

Highly immunocompromised pediatric and adult hematopoietic cell transplant (HCT) recipients frequently experience respiratory infections caused by viruses that are less virulent in immunocompetent individuals. Most of these infections, with the exception of rhinovirus as well as adenovirus and parainfluenza virus in tropical areas, are seasonal variable and occur before and after HCT. Infectious disease management includes sampling of respiratory specimens from nasopharyngeal washes or swabs as well as sputum and tracheal or tracheobronchial lavages. These are subjected to improved diagnostic tools including multiplex PCR assays that are routinely used allowing for expedient detection of all respiratory viruses. Disease progression along with high mortality is frequently associated with respiratory syncytial virus, parainfluenza virus, influenza virus, and metapneumovirus infections. In this review, we discuss clinical findings and the appropriate use of diagnostic measures. Additionally, we also discuss treatment options and suggest new drug formulations that might prove useful in treating respiratory viral infections. Finally, we shed light on the role of the state of immune reconstitution and on the use of immunosuppressive drugs on the outcome of infection.

Respiratory Viral Infections in Transplant Recipients

Respiratory viral infections (RVIs) are common among the general population; however, these often mild viral illnesses can lead to serious morbidity and mortality among recipients of hematopoietic stem cell and solid organ transplantation. The disease spectrum ranges from asymptomatic or mild infections to life-threatening lower respiratory tract infection or long-term airflow obstruction syndromes. Progression to lower respiratory tract infection or to respiratory failure is determined by the intrinsic virulence of the specific viral pathogen as well as various host factors, including the type of transplantation, status of the host’s immune dysfunction, the underlying disease, and other comorbidities. This chapter focuses on the epidemiology, clinical manifestations, diagnosis, and management of RVIs in this susceptible population and includes respiratory syncytial virus, parainfluenza virus, human metapneumovirus, influenza virus, human coronavirus, and human rhinovirus. The optimal management of these infections is limited by the overall paucity of available treatment, highlighting the need for new antiviral drug or immunotherapies.

Community acquired respiratory virus infections in cancer patients-Guideline on diagnosis and management by the Infectious Diseases Working Party of the German Society for haematology and Medical Oncology

BACKGROUND

Community acquired viruses (CRVs) may cause severe disease in cancer patients. Thus, efforts should be made to diagnose CRV rapidly and manage CRV infections accordingly.

METHODS

A panel of 18 clinicians from the Infectious Diseases Working Party of the German Society for Haematology and Medical Oncology have convened to assess the available literature and provide recommendations on the management of CRV infections including influenza, respiratory syncytial virus, parainfluenza virus, human metapneumovirus and adenovirus.

RESULTS

CRV infections in cancer patients may lead to pneumonia in approximately 30% of the cases, with an associated mortality of around 25%. For diagnosis of a CRV infection, combined nasal/throat swabs or washes/aspirates give the best results and nucleic acid amplification based-techniques (NAT) should be used to detect the pathogen. Hand hygiene, contact isolation and face masks have been shown to be of benefit as general infection management. Causal treatment can be given for influenza, using a neuraminidase inhibitor, and respiratory syncytial virus, using ribavirin in addition to intravenous immunoglobulins. Ribavirin has also been used to treat parainfluenza virus and human metapneumovirus, but data are inconclusive in this setting. Cidofovir is used to treat adenovirus pneumonitis.

CONCLUSIONS

CRV infections may pose a vital threat to patients with underlying malignancy. This guideline provides information on diagnosis and treatment to improve the outcome.

CT findings in viral lower respiratory tract infections caused by parainfluenza virus, influenza virus and respiratory syncytial virus

Viral lower respiratory tract infections (LRTIs) can present with a variety of computed tomography (CT) findings. However, identifying the contribution of a particular virus to CT findings is challenging due to concomitant infections and the limited data on the CT findings in viral LRTIs. We therefore investigate the CT findings in different pure viral LRTIs.All patients who underwent bronchoalveolar lavage (BAL) and were diagnosed with LRTIs caused by parainfluenza virus (PIV), influenza virus, or respiratory syncytial virus (RSV) between 1998 and 2014 were enrolled in a tertiary hospital in Seoul, South Korea. A pure viral LRTI was defined as a positive viral culture from BAL without any positive evidence from respiratory or blood cultures, or from polymerase chain reaction (PCR), or from serologic tests for bacteria, fungi, mycobacteria, or other viruses.CT images of 40 patients with viral LRTIs were analyzed: 14 with PIV, 14 with influenza virus, and 12 with RSV. Patch consolidation (≥1 cm or more than 1 segmental level) was found only in PIV (29%) (P = 0.03), by which CT findings caused by PIV could resemble those seen in bacterial LRTIs. Ground-glass opacities were seen in all cases of influenza virus and were more frequent than in PIV (71%) and RSV (67%) (P = 0.05). Bronchial wall thickening was more common in influenza virus (71%) and RSV (67%) LRTIs than PIV LRTIs (21%) (P = 0.02). With respect to anatomical distribution, PIV infections generally affected the lower lobes (69%), while influenza virus mostly caused diffuse changes throughout the lungs (57%), and RSV frequently formed localized patterns in the upper and mid lobes (44%).The CT findings in LRTIs of PIV, influenza virus, and RSV can be distinguished by certain characteristics. These differences could be useful for early differentiation of these viral LRTIs, and empirical use of appropriate antiviral agents.

Noninfectious Generalized Bronchiolitis in the Setting of Allogeneic Stem Cell Transplantation: A Potential Mimic of Lower Respiratory Tract Infection

RATIONALE AND OBJECTIVES

To describe a little-known therapy-related small-airway phenomenon presumably caused by mucosal irritation in patients undergoing allogeneic stem cell transplantation (allo-SCT).

MATERIALS AND METHODS

Retrospective database search at our institution identified 739 hematologic patients who underwent chemotherapy + allo-SCT between September 2004 and March 2014. After infectious pulmonary complications were excluded, 75 patients (female = 24; male = 51; median age = 47 years) with signs of generalized bronchiolitis (GB) on chest high-resolution computed tomography were identified. Computed tomography (CT) was performed proximate to chemotherapy onset; 92% had follow-up CT (mean, 1.9 weeks). The presence of centrilobular nodules, bronchial wall thickening (BWT), tree-in-bud (distributed diffuse vs. focal), ground-glass opacity, airspace opacification, luminal impactions, and air trapping was correlated with occurrence and duration of oral mucositis and therapy characteristics. Intensity of tree-in-bud and centrilobular nodules was graded absent (grade = 0), moderate (grade = 1), or marked (grade = 2).

RESULTS

Overall incidence of GB among allo-SCT patients was 10.14%. GB was diagnosed at the time point of transplantation with a mean duration of CT findings of 4 weeks (±2.7). Tree-in-bud (17% [grade 2] and 83% [grade 1]) and BWT were present in 100% of the patients. Centrilobular nodules diffusely distributed were found in 45.5% of patients (20% [grade 2], 24% [grade 1], and 56% [none]). Air trapping and mosaic pattern were found in 13% and 16% of the patients, respectively. Resolution of GB was spontaneous. GB and its severity correlated with the temporal course and grade of oral mucositis; frequency and degree were not significantly influenced by the chemotherapy regimen. The incidence of GB in high-resolution computed tomography was statistically and significantly higher in patients with oral mucositis (P < 0.035).

CONCLUSIONS

GB is frequent during chemotherapy for allo-SCT and is characterized by an even distribution of tree-in-bud, BWT, centrilobular nodules, mild clinical symptoms, and spontaneous resolution.

Hematologic neoplasms: Interpreting lung findings in chest computed tomography

Lung disease is very common in patients with hematologic neoplasms and varies in function of the underlying disease and its treatment. Lung involvement is associated with high morbidity and mortality, so it requires early appropriate treatment. Chest computed tomography (CT) and the analysis of biologic specimens are the first line diagnostic tools in these patients, and sometimes invasive methods are necessary. Interpreting the images requires an analysis of the clinical context, which is often complex. Starting from the knowledge about the differential diagnosis of lung findings that radiologists acquire during training, this article aims to explain the key clinical and radiological aspects that make it possible to orient the diagnosis correctly and to understand the current role of CT in the treatment strategy for this group of patients.

Hematologic neoplasms: interpreting lung findings in chest computed tomography

La patología pulmonar en la historia de un paciente con neoplasia hematológica es muy frecuente y variable en función de la enfermedad de base y la terapia recibida. La morbimortalidad asociada es alta, por lo que requiere un tratamiento correcto y precoz. La tomografía computarizada (TC) torácica, junto con el análisis de muestras biológicas, son las herramientas de diagnóstico de primera línea empleadas en estos pacientes, y en determinados casos se requieren métodos invasivos. La interpretación de las imágenes exige el análisis de un contexto clínico en muchas ocasiones complejo. Partiendo del conocimiento que adquiere el radiólogo en su formación sobre el diagnóstico diferencial de los hallazgos pulmonares, el objetivo de este trabajo es explicar los aspectos clínicos y radiológicos claves que permiten orientar correctamente el diagnóstico y asimilar el papel actual de la TC en la estrategia terapéutica de este grupo de enfermos.

Acute pulmonary complications in patients with hematologic malignancies

Various acute pulmonary complications may occur in patients with hematologic malignancies because they are in an immunocompromised state due to systemic disease or to chemotherapy or hematopoietic stem cell transplantation. Pulmonary complications may arise from other treatment regimens, as well, or from direct pulmonary involvement in the malignant disease process. The differential diagnosis of pulmonary opacities in patients with hematologic malignancies is broad and includes both infectious and noninfectious causes. Pulmonary hemorrhage, edema, leukostasis, and pneumonia are well-known and common acute pulmonary complications. Less common complications are now encountered with increasing frequency because of the increasing complexity of therapeutic regimens for hematologic malignancies, which may include various drugs that are in clinical trials or were recently released to market. These once uncommon acute pulmonary complications include retinoic acid syndrome, tyrosine kinase inhibitor-induced pulmonary complications, engraftment syndrome, and hemophagocytic lymphohistiocytosis. It is often difficult to differentiate between these entities. However, the clinical setting and radiologic imaging findings may provide clues for interpreting imaging findings of abnormal pulmonary opacity in patients with a hematologic malignancy. Pulmonary hemorrhage is characterized by a sudden onset of symptoms and rapid progression of pulmonary imaging abnormalities and usually occurs in patients with impaired coagulation or a predisposition to bleed. Pulmonary edema should be considered when typical findings of hydrostatic pulmonary edema are seen. Pulmonary leukostasis develops in patients with hyperleukocytosis and leads to symptoms such as a cough, fever, and dyspnea. Various types of pneumonia may develop, depending on the degree and duration of immunosuppression in the patient. Retinoic acid syndrome, tyrosine kinase inhibitor-induced pulmonary complications, and engraftment syndrome occur after specific treatments, so a detailed medical history including recent or current treatments may be helpful for diagnosis. Accurate differentiation of these entities allows their appropriate management, with resultant decreases in morbidity and mortality.

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.

Mortality rates of human metapneumovirus and respiratory syncytial virus lower respiratory tract infections in hematopoietic cell transplantation recipients

Human metapneumovirus (HMPV), a common respiratory virus, can cause severe disease in pre- and post-hematopoietic cell transplantation (HCT) recipients. We conducted a retrospective cohort analysis in HCT patients with HMPV (n = 23) or respiratory syncytial virus (n = 23) detected in bronchoalveolar lavage samples by reverse transcription PCR between 2006 and 2011 to determine disease characteristics and factors associated with outcome. Mortality rates at 100 days were 43% for both HMPV and respiratory syncytial virus lower respiratory tract disease. Steroid therapy, oxygen requirement >2 L or mechanical ventilation, and bone marrow as cell source were significant risk factors for overall and virus-related mortality in multivariable models, whereas the virus type was not. The presence of centrilobular/nodular radiographic infiltrates was a possible protective factor for mechanical ventilation. Thus, HMPV lower respiratory tract disease is associated with high mortality in HCT recipients. Earlier detection in combination with new antiviral therapy is needed to reduce mortality among HCT recipients.

Which patients should be tested for viruses on bronchoalveolar lavage fluid?

Bronchoalveolar lavage (BAL) is a major diagnostic tool in lung diseases, including viral respiratory infections. We aimed to better define the situations where viral tests should be performed on BAL fluid (BALF). We retrospectively studied all cases where viral tests [immunofluorescence, immunocytochemistry, viral culture, and/or polymerase chain reaction (PCR)] were performed on BALF during a period of 1 year (2008) in our institution. We compared the characteristics of patients with virus-positive versus virus-negative BALF. Of the 636 BALF samples sent to the microbiology laboratory, 232 underwent viral tests. Of these, 70 (30 %) were positive and identified 85 viruses: herpes simplex virus (HSV)-1 (n = 27), cytomegalovirus (CMV, n = 23), Epstein–Barr virus (EBV, n = 18), human herpesvirus (HHV)-6 (n = 12), respiratory syncytial virus (RSV, n = 3), rhinovirus (n = 1), and adenovirus (n = 1). The variables associated with positive viral tests on univariate analysis were immunosuppression [human immunodeficiency virus (HIV), corticosteroids >10 mg/day for ≥3 weeks, or other immunosuppressive therapy], ground-glass attenuations on computed tomography (CT) scanning, late-onset ventilator-associated pneumonia (VAP), and durations of (i) hospital stay, (ii) intensive care unit (ICU) stay, and (iii) mechanical ventilation before BAL (p < 0.01 for each comparison). On multivariate analysis, only immunosuppression [odds ratio (OR) 6.4, 95 % confidence interval (CI) [2.8–14.3], p < 0.0001] and ground-glass attenuations (OR 3.7, 95 % CI [1.8–7.7], p = 0.0004) remained associated with virus-positive BAL. None of the viral tests performed on BALF for the initial assessment of diffuse infiltrative lung disease (n = 15) was positive. PCR improved the diagnostic yield of viral tests on BALF by 50 %. Testing for viruses on BALF should be mostly restricted to immunocompromised patients with acute respiratory diseases and/or patients with unexplained ground-glass attenuations on CT scanning.

CT of viral lower respiratory tract infections in adults: comparison among viral organisms and between viral and bacterial infections

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.

Clinical and radiological features of respiratory syncytial virus in solid organ transplant recipients: a single-center experience

BACKGROUND

Respiratory syncytial virus (RSV) infections range from upper respiratory illness to severe lower respiratory disease. There is no universally accepted treatment for RSV in solid organ transplant (SOT) recipients.

METHODS

Retrospective review of adult SOT patients with RSV infections, between January 2007 and December 2009, in a single transplant center was performed.

RESULTS

During the 3-year period, a total of 24 adults developed RSV infection, including 12 (50%) SOT recipients (5 kidneys, 4 livers, and 3 lungs). Most cases were seen in 2009 during the influenza H1N1 pandemic, likely as a result of increased testing. In 83% of the cases, the diagnosis was based on RSV antigen detection, which was also used to follow subsequent shedding (mean duration: 20.6 days). Most of the cases presented with lower respiratory disease and required hospitalization. All the patients were on at least two classes of immunosuppressive drugs. We observed a lower lymphocyte count in patients with lower respiratory tract infection. Computed tomography was superior to chest x-ray in demonstrating pulmonary disease, with the most common findings being pulmonary nodules and ground-glass opacities. Novel radiographic findings were small cavities and pleural effusions. No co-infections were documented, and no mortality could be attributed to RSV. Inhaled or oral ribavirin was administered in 67% of the cases, with variations in the treatment regimens.

CONCLUSION

SOT recipients accounted for half of all adult cases of RSV at our institution. Type and length of treatment varied widely, and we cannot conclude that outcomes differed between treatments with oral or inhaled ribavirin. Current therapeutic management of RSV in SOT is empiric, and can be rather expensive and difficult, without clear evidence of effectiveness.

Chest computed tomographic imaging characteristics of viral acute lower respiratory tract illnesses: a case-control study

OBJECTIVE

This study aimed to determine whether computed tomographic (CT) findings can distinguish viral lower respiratory tract illness (LRTI) from other conditions.

METHODS

Three radiologists reviewed CT images of patients with LRTI who underwent testing for respiratory viral infection. Imaging findings in subjects with positive viral assays were compared with subjects with negative assays.

RESULTS

Of 334 subjects, 93 were positive for viral LRTI. Tree-in-bud opacities and bronchial wall thickening were observed more often in subjects with viral LRTI (P < 0.05). Multifocal airspace disease occurred with similar frequency in both groups. Diffuse airspace opacification was negatively associated with viral LRTI. Pleural effusion was observed more often among subjects without viral LRTI (P < 0.001).

CONCLUSIONS

Airway inflammatory changes such as tree-in-bud opacities, bronchial wall thickening, and peribronchiolar consolidation are associated with community-acquired viral LRTI. Recognition of these findings should prompt testing for viral infection. Multifocal consolidation is commonly found in cases of viral LRTI but is nonspecific.

Comparison of initial high resolution computed tomography features in viral pneumonia between metapneumovirus infection and severe acute respiratory syndrome

OBJECTIVE

To review and compare initial high resolution computed tomography (HRCT) findings in patients with metapneumovirus pneumonia and severe acute respiratory syndrome (SARS-Coronovirus).

MATERIALS AND METHODS

4 cases of metapneumovirus pneumonia (mean age of 52.3 years) in an institutional outbreak (Castle Peak Hospital) in 2008 and 38 cases of SARS-coronovirus (mean age of 39.6 years) admitted to Tuen Mun hospital during an epidemic outbreak in 2003 were included. HRCT findings of the lungs for all patients were retrospectively reviewed by two independent radiologists.

RESULTS

In the metapneumovirus group, common HRCT features were ground glass opacities (100%), consolidation (100%), parenchymal band (100%), bronchiectasis (75%). Crazy paving pattern was absent. They were predominantly subpleural and basal in location and bilateral involvement was observed in 50% of patients. In the SARS group, common HRCT features were ground glass opacities (92.1%), interlobular septal thickening (86.8%), crazy paving pattern (73.7%) and consolidation (68%). Bronchiectasis was not seen. Majority of patient demonstrated segmental or lobar in distribution and bilateral involvement was observed in 44.7% of patients. Pleural effusion and lymphadenopathy were of consistent rare features in both groups.

CONCLUSION

Ground glass opacities, interlobular septal thickening and consolidations were consistent HRCT manifestations in both metapneumovirus infection and SARS. The presence of bronchiectasis (0% in SARS) may point towards metapneumovirus while crazy paving pattern is more suggestive of SARS.

Pleuropulmonary Changes Induced by Drugs in Patients with Hematologic Diseases

Patients with hematologic diseases who are being treated with therapy drugs, or receive radiation therapy or blood transfusions may develop a host of potentially fatal infectious and noninfectious pulmonary complications [1]. The increased complexity of multimodality and high-dose treatment regimens with the intended benefit of augmented antineoplastic efficacy and prolonged disease-free survival, the use of a panel of novel drugs to treat malignant and nonmalignant hematologic conditions (e.g., azacytidine, bortezomib, cladribine, dasatinib, fludarabine, imatinib, lenalidomide, rituximab, and thalidomide), total body irradiation (TBI) and hematopietic stem cell transplantation (HSCT) have increased the incidence of severe sometimes life-threatening pulmonary complications.

Thoracic CT findings of novel influenza A (H1N1) infection in immunocompromised patients

The goal of this study is to describe the spectrum of initial and follow-up CT findings of novel influenza A (H1N1) infection in a series of immunocompromised patients. Eight immunocompromised patients with documented novel influenza A (H1N1) had CT imaging at our institution between May 2009 and August 2009. A total of 20 CTs (initial and follow-up) were reviewed for the presence, severity, and distribution of the following: ground glass opacity, consolidation, interlobular septal thickening, mosaic perfusion, airway wall thickening, airway dilatation, nodules, cysts, pleural effusion, pericardial effusion, lymphadenopathy, and air trapping. The most common findings were airway thickening/dilatation, peribronchial ground glass opacity, centrilobular nodules, and tree-in-bud opacities. Peripheral consolidation involving the lower lobes was also a common pattern. Findings frequently involved all lobes and were closely associated with either large or small airways. Two patients presented with atypical CT findings including focal lobar consolidation and patchy lower lobe consolidation with soft tissue centrilobular nodules. Most survivors showed near complete resolution of findings within 35 days. CT scans in immunocompromised patients with novel influenza H1N1 commonly show a strong airway predominance of findings or peripheral areas of consolidation involving the lower lobes. A subset of patients with novel influenza A (H1N1) will show findings not typical of viral infection.

Viral pneumonia after hematopoietic stem cell transplantation: high-resolution CT findings

Hematopoietic stem cell transplantation (HSCT) is the treatment of choice for many hematologic malignancies and nonmalignant disorders of bone marrow function. Pulmonary infections from bacterial, fungal, and viral organisms are a major cause of morbidity and mortality in patients after HSCT. The radiographic and high-resolution computed tomography (HRCT) findings of the different lower respiratory tract viral infections are quite similar. Findings of viral pneumonia on HRCT include small poorly defined centrilobular nodules and patchy, often bilateral, areas of peribronchial ground-glass opacity and consolidation. Air trapping may be present because of associated bronchiolitis. Interlobular septal thickening, bronchial wall thickening, and tree-in-bud opacities may also be present. Advanced viral pneumonia with diffuse alveolar damage is characterized by patchy or confluent consolidation and ground-glass opacities. Although nonspecific, in the correct clinical setting, these HRCT findings can help suggest the diagnosis of viral pneumonia in recipients of HSCT.