Pulmonary infections after bone marrow transplantation: high-resolution CT findings in 111 patients

Clinical characteristics and outcomes of community-acquired pneumonia in solid organ transplant recipients

BACKGROUND

Pneumonia is a frequent complication of solid organ transplantation that adversely impacts both graft and recipient survival. There is a paucity of data on community-acquired pneumonia (CAP) in transplant recipients, particularly the long term outcomes. We conducted a study to compare the clinical characteristics and outcomes of pneumonia in solid organ transplant (SOT) recipients to those in non-transplant (NT) recipients.

MATERIAL AND METHODS

Clinical characteristics were abstracted from electronic medical records. Outcomes included time to hospital discharge, short and long-term mortality. Inverse-propensity score weights were assigned to account for between-group differences. Adjusted analysis included a weighted logistic regression. Results were reported as odds ratios with a corresponding 95 % confidence interval (CI).

RESULTS

A total of 7449 patients were admitted with CAP. Patients were divided into two groups: SOT recipients 42 (0.56 %) and NT recipients 7396 (99.2 %). SOT recipients were younger, more commonly males, with higher prevalence of comorbidities. After accounting for inverse-propensity score weighting, the odds of mortality were higher in SOT recipients in hospital, at 30 days and at 1 year. The magnitude of increase in mortality for SOT recipients was greatest at 1 year with 1.41 (95 % CI: 1.38-1.44) times higher odds.

CONCLUSION

In patients with CAP, SOT recipients are younger, more commonly male and have more co-morbidities compared with NT recipients. They also have higher 1 year mortality after adjustment. Clinicians must be vigilant toward the pronounced long-term mortality risk among these patients and ensure continued follow-up care for them.

Lung and sinus fungal infection imaging in immunocompromised patients

BACKGROUND

Imaging is a key diagnostic modality for suspected invasive pulmonary or sinus fungal disease and may help to direct testing and treatment. Fungal diagnostic guidelines have been developed and emphasize the role of imaging in this setting. We review and summarize evidence regarding imaging for fungal pulmonary and sinus disease (in particular invasive aspergillosis, mucormycosis and pneumocystosis) in immunocompromised patients.

OBJECTIVES

We reviewed data on imaging modalities and findings used for diagnosis of invasive fungal pulmonary and sinus disease.

SOURCES

References for this review were identified by searches of PubMed, Google Scholar, Embase and Web of Science through 1 April 1 2023.

CONTENT

Computed tomography imaging is the method of choice for the evaluation of suspected lung or sinus fungal disease. Although no computed tomography radiologic pattern is pathognomonic of pulmonary invasive fungal disease (IFD) the halo sign firstly suggests an angio-invasive pulmonary aspergillosis while the Reversed Halo Sign is more suggestive of pulmonary mucormycosis in an appropriate clinical setting. The air crescent sign is uncommon, occurring in the later stages of invasive aspergillosis in neutropenic patients. In contrast, new cavitary lesions should suggest IFD in moderately immunocompromised patients. Regarding sinus site, bony erosion, peri-antral fat or septal ulceration are reasonably predictive of IFD.

IMPLICATIONS

Imaging assessment of the lung and sinuses is an important component of the diagnostic work-up and management of IFD in immunocompromised patients. However, radiological features signs have sensitivity and specificity that often vary according to underlying disease states. Periodic review of imaging studies and diagnostic guidelines characterizing imaging findings may help clinicians to consider fungal infections in clinical care thereby leading to an earlier confirmation and treatment of IFD.

Imaging of Invasive Fungal Infections- The Role of PET/CT

Over the last decades, the population at risk for invasive fungal disease (IFD) has increased because of medical therapy advances and diseases compromising patients' immune systems. The high morbidity and mortality associated with invasive fungal disease in the immunocompromised present the challenge of early diagnosis of the IFD and the need to closely monitor the infection during treatment. The definitive diagnosis of invasive fungal disease based on culture or histopathological methods often has reduced diagnostic accuracy in the immunocompromised and may be very invasive. Less invasive and indirect evidence of the fungal infection by serology and imaging has been used for the early diagnosis of fungal infection before definitive results are available or when the definitive methods of diagnosis are suboptimal. Imaging in invasive fungal disease is a non-invasive biomarker that helps in the early diagnosis of invasive fungal disease but helps follow-up the infection during treatment. Different imaging modalities are used in the workup to evaluate fungal disease. The different imaging modalities have advantages and disadvantages at different sites in the body and may complement each other in the management of IFD. Positron emission tomography integrated with computed tomography with [18F]Fluorodeoxyglucose (FDG PET/CT) has helped manage IFD. The combined functional data from PET and anatomical data from the CT from almost the whole body allows noninvasive evaluation of IFD and provides a semiquantitative means of assessing therapy. FDG PET/CT adds value to anatomic-based only imaging modalities. The nonspecificity of FDG uptake has led to the evaluation of other tracers in the assessment of IFD. However, these are mainly still at the preclinical level and are yet to be translated to humans. FDG PET/CT remains the most widely evaluated radionuclide-based imaging modality in IFD management. The limitations of FDG PET/CT must be well understood, and more extensive prospective studies in uniform populations are needed to validate its role in the management of IFD that can be international guidelines.

Pre-emptive antifungal therapy versus empirical antifungal therapy for febrile neutropenia in people with cancer

BACKGROUND

Intensive cytotoxic chemotherapy for people with cancer can cause severe and prolonged cytopenia, especially neutropenia, a critical condition that is potentially life-threatening. When manifested by fever and neutropenia, it is called febrile neutropenia (FN). Invasive fungal disease (IFD) is one of the serious aetiologies of chemotherapy-induced FN. In pre-emptive therapy, physicians only initiate antifungal therapy when an invasive fungal infection is detected by a diagnostic test. Compared to empirical antifungal therapy, pre-emptive therapy may reduce the use of antifungal agents and associated adverse effects, but may increase mortality. The benefits and harms associated with the two treatment strategies have yet to be determined.  OBJECTIVES: To assess the relative efficacy, safety, and impact on antifungal agent use of pre-emptive versus empirical antifungal therapy in people with cancer who have febrile neutropenia.

SEARCH METHODS

We searched CENTRAL, MEDLINE Ovid, Embase Ovid, and ClinicalTrials.gov to October 2021.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared pre-emptive antifungal therapy with empirical antifungal therapy for people with cancer.

DATA COLLECTION AND ANALYSIS

We identified 2257 records from the databases and handsearching. After removing duplicates, screening titles and abstracts, and reviewing full-text reports, we included seven studies in the review. We evaluated the effects on all-cause mortality, mortality ascribed to fungal infection, proportion of antifungal agent use (other than prophylactic use), duration of antifungal use (days), invasive fungal infection detection, and adverse effects for the comparison of pre-emptive versus empirical antifungal therapy. We presented the overall certainty of the evidence for each outcome according to the GRADE approach.

MAIN RESULTS

This review includes 1480 participants from seven randomised controlled trials. Included studies only enroled participants at high risk of FN (e.g. people with haematological malignancy); none of them included participants at low risk (e.g. people with solid tumours).  Low-certainty evidence suggests there may be little to no difference between pre-emptive and empirical antifungal treatment for all-cause mortality (risk ratio (RR) 0.97, 95% confidence interval (CI) 0.72 to 1.30; absolute effect, reduced by 3/1000); and for mortality ascribed to fungal infection (RR 0.92, 95% CI 0.45 to 1.89; absolute effect, reduced by 2/1000). Pre-emptive therapy may decrease the proportion of antifungal agent used more than empirical therapy (other than prophylactic use; RR 0.71, 95% CI 0.47 to 1.05; absolute effect, reduced by 125/1000; very low-certainty evidence). Pre-emptive therapy may reduce the duration of antifungal use more than empirical treatment (mean difference (MD) -3.52 days, 95% CI -6.99 to -0.06, very low-certainty evidence). Pre-emptive therapy may increase invasive fungal infection detection compared to empirical treatment (RR 1.70, 95% CI 0.71 to 4.05; absolute effect, increased by 43/1000; very low-certainty evidence). Although we were unable to pool adverse events in a meta-analysis, there seemed to be no apparent difference in the frequency or severity of adverse events between groups. Due to the nature of the intervention, none of the seven RCTs could blind participants and personnel related to performance bias. We identified considerable clinical and statistical heterogeneity, which reduced the certainty of the evidence for each outcome. However, the two mortality outcomes had less statistical heterogeneity than other outcomes.

AUTHORS' CONCLUSIONS

For people with cancer who are at high-risk of febrile neutropenia, pre-emptive antifungal therapy may reduce the duration and rate of use of antifungal agents compared to empirical therapy, without increasing over-all and IFD-related mortality; but the evidence regarding invasive fungal infection detection and adverse events was inconsistent and uncertain.

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.

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.

Imaging features of fungal pneumonia in haematopoietic stem cell transplant patients

Patients who have received haematopoietic stem cell transplantation (HSCT) have a high rate of pulmonary complications, and in this immunosuppressed population, fungal pneumonia is of great concern. Fungal pneumonia can have a similar appearance to non-infectious pulmonary processes in HSCT patients, and radiologists should be familiar with the subtle features that may help to differentiate these disease entities. The focus of this article is on the diagnosis of fungal pneumonia in HSCT patients with an emphasis on radiologists’ roles in establishing the diagnosis of fungal pneumonia and the guidance of clinical management.

Guidance on Imaging for Invasive Pulmonary Aspergillosis and Mucormycosis: From the Imaging Working Group for the Revision and Update of the Consensus Definitions of Fungal Disease from the EORTC/MSGERC

BACKGROUND

Clinical imaging in suspected invasive fungal disease (IFD) has a significant role in early detection of disease and helps direct further testing and treatment. Revised definitions of IFD from the EORTC/MSGERC were recently published and provide clarity on the role of imaging for the definition of IFD. Here, we provide evidence to support these revised diagnostic guidelines.

METHODS

We reviewed data on imaging modalities and techniques used to characterize IFDs.

RESULTS

Volumetric high-resolution computed tomography (CT) is the method of choice for lung imaging. Although no CT radiologic pattern is pathognomonic of IFD, the halo sign, in the appropriate clinical setting, is highly suggestive of invasive pulmonary aspergillosis (IPA) and associated with specific stages of the disease. The ACS is not specific for IFD and occurs in the later stages of infection. By contrast, the reversed halo sign and the hypodense sign are typical of pulmonary mucormycosis but occur less frequently. In noncancer populations, both invasive pulmonary aspergillosis and mucormycosis are associated with "atypical" nonnodular presentations, including consolidation and ground-glass opacities.

CONCLUSIONS

A uniform definition of IFD could improve the quality of clinical studies and aid in differentiating IFD from other pathology in clinical practice. Radiologic assessment of the lung is an important component of the diagnostic work-up and management of IFD. Periodic review of imaging studies that characterize findings in patients with IFD will inform future diagnostic guidelines.

Johnson E, Littlechild J, Winlove CP, Vollmer F, Gow NAR. Biosensors and Diagnostics for Fungal Detection

Early detection is critical to the successful treatment of life-threatening infections caused by fungal pathogens, as late diagnosis of systemic infection almost always equates with a poor prognosis. The field of fungal diagnostics has some tests that are relatively simple, rapid to perform and are potentially suitable at the point of care. However, there are also more complex high-technology methodologies that offer new opportunities regarding the scale and precision of fungal diagnosis, but may be more limited in their portability and affordability. Future developments in this field are increasingly incorporating new technologies provided by the use of new format biosensors. This overview provides a critical review of current fungal diagnostics and the development of new biophysical technologies that are being applied for selective new sensitive fungal biosensors to augment traditional diagnostic methodologies.

Respiratory pathogens associated with intubated pediatric patients following hematopoietic cell transplant

BACKGROUND

We describe organisms found in the respiratory tracts of a multicenter cohort of pediatric hematopoietic cell transplant (HCT) recipients with respiratory failure.

METHODS

Twelve centers contributed up to 25 pediatric allogeneic HCT recipients requiring mechanical ventilation for respiratory failure to a retrospective database. Positive respiratory pathogens and method of obtaining sample were recorded. Outcomes were assessed using Mann-Whitney U test or chi-squared analysis.

RESULTS

Of the 222 patients in the database, ages 1 month through 21 years, 34.6% had a positive respiratory culture. 105 pathogens were identified in 77 patients; of those, 48.6% were viral, 34.3% bacterial, 16.2% fungal, and 1% parasitic. PICU mortality with a respiratory pathogen was 68.8% compared to 54.9% for those without a respiratory pathogen (P = .045). Those with a positive respiratory pathogen had longer PICU length of stay, 20 days (IQR 14.0, 36.8) vs 15 (IQR 6.5, 32.0), P = .002, and a longer course of mechanical ventilation, 17 days (IQR 10, 29.5) vs 8 (3, 17), P < .0001. Method of pathogen identification, type of pathogen, and the presence of multiple pathogens were not associated with changes in PICU outcomes.

CONCLUSIONS

In this multicenter retrospective cohort of intubated pediatric post-HCT patients, there was high variability in the respiratory pathogens identified. Type of pathogen and method of detection did not affect PICU mortality. The presence of any organism leads to increased PICU mortality, longer PICU stay, and increased duration of mechanical ventilation suggesting that early detection and treatment of pathogens may be beneficial in this population.

CT Halo sign: A systematic review

PURPOSE

The CT Halo sign or Halo sign (HS) refers to ground-glass opacity surrounding a nodule or mass in the lung parenchyma. We conducted a systematic review to find the etiological associations of HS. We also evaluated the diagnostic performances of HS for invasive fungal infections (IFI) in immunosuppressed patients.

METHOD

The systematic review was conducted as per PRISMA guidelines. We searched the PubMed and EMBASE database till June 2018 without any restrictions. Only case reports, case series and original articles published in English language were included. A database created from the electronic searches was compiled and subsequent analysis was done. [PROSPERO registration: CRD42018094739] RESULTS: 168 studies were eligible, which included 51 case reports, 15 prospective studies, 102 retrospective studies. A total of 1977 patients (out of 6371) with HS were identified with age range between <1year-94years. The most common diagnosis in the immunosuppressed, mixed, immunocompetent and not specified groups were IFI (86.9 %, n = 1194), Cryptococcosis (51.6 %, n = 124), Cryptococcosis (40 %, n = 20) and lung neoplasms (81.8 %, n = 36) respectively. 14 studies (11 retrospective, 3 prospective) were included in quantitative analysis. The pooled sensitivity(sn), specificity(sp) and odd's ratio (OR) of HS for diagnosing IFI were 50.4 %, 91 % and 6.61 respectively. Also, HS could not reliably differentiate IPA from mucormycosis in the pooled analysis.

CONCLUSIONS

HS can be seen in a large number of diverse conditions both in immunosuppressed and immunocompetent population. In immunosuppressed patients HS is specific for IFI but cannot rule it out. Additionally, it cannot reliably distinguish between IPA and mucormycosis.

Chest Computed Tomography Abnormalities and Their Relationship to the Clinical Manifestation of Respiratory Syncytial Virus Infection in a Genetically Confirmed Outbreak

Studies reporting chest images of respiratory syncytial virus (RSV)-induced lower respiratory tract infection (LRTI) in an outbreak setting and their relationship to the clinical manifestation are limited. During a genetically confirmed RSV outbreak, eight patients underwent both chest X-ray and computed tomography (CT). Among these, 5 cases had newly appearing abnormalities on CT, although chest X-ray was able to detect abnormalities in only 2 cases (40%). Although bronchial wall thickening was common, other findings and their distribution were variable, even in an outbreak setting. All patients with both a history of anticancer chemotherapy against hematological cancer and lower respiratory symptoms, such as wheezing, sputum, and hypoxemia, had abnormalities on CT, suggesting that these two factors might be important for predicting the existence of LRTI in RSV-infected patients.

Cost-effectiveness of antifungal prophylaxis, preemptive therapy, or empiric treatment following allogeneic hematopoietic stem cell transplant

BACKGROUND

Invasive fungal infection (IFI) is a life-threatening complication of allogeneic hematopoietic stem cell transplantation (HSCT) that is also associated with excess healthcare costs. Current approaches include universal antifungal prophylaxis, preemptive therapy based on biomarker surveillance, and empiric treatment initiated in response to clinical signs/symptoms. However, no study has directly compared the cost-effectiveness of these treatment strategies for an allogeneic HSCT patient population.

METHODS

We developed a state transition model to study the impact of treatment strategies on outcomes associated with IFIs in the first 100 days following myeloablative allogeneic HSCT. We compared three treatment strategies: empiric voriconazole, preemptive voriconazole (200 mg), or prophylactic posaconazole (300 mg) for the management of IFIs. Preemptive treatment was guided by scheduled laboratory surveillance with galactomannan (GM) testing. Endpoints were cost and survival at 100 days post-HSCT.

RESULTS

Empiric treatment was the least costly ($147 482) and was equally effective (85.2% survival at 100 days) as the preemptive treatment strategies. Preemptive treatments were slightly more costly than empiric treatment (GM cutoff ≥ 1.0 $147 910 and GM cutoff ≥ 0.5 $148 108). Preemptive therapy with GM cutoff ≥ 1.0 reduced anti-mold therapy by 5% when compared to empiric therapy. Posaconazole prophylaxis was the most effective (86.6% survival at 100 days) and costly ($152 240) treatment strategy with a cost of $352 415 per life saved when compared to empiric therapy.

CONCLUSIONS

One preemptive treatment strategy reduced overall anti-mold drug exposure but did not reduce overall costs. Prevention of IFI using posaconazole prophylaxis was the most effective treatment strategy and may be cost-effective, depending upon the willingness to pay per life saved.

Clinical diagnostic value of spiral CT in invasive pulmonary fungal infection

This study explored the diagnostic value of computed tomography (CT) in pulmonary fungal infection to provide a theoretical basis for the clinical diagnosis of pulmonary fungal infections. The clinical data of 82 suspected invasive fungal infection (IFI) patients admitted to the Department of Critical Care Medicine of The Affiliated Hospital of Qingdao University from January 2016 to May 2018 were retrospectively analyzed, and 64 of them were diagnosed with IFI by pathology and sputum culture. The CT results of the 82 patients were compared with the X-ray results in order to analyze the diagnostic value of CT imaging. Taking pathological diagnosis as the gold standard, the number of true-negative, true-positive, false-negative and false-positive results in X-ray diagnosis were 13, 43, 21 and 5, respectively, while those in CT diagnosis were 11, 59, 5 and 7, respectively. The sensitivity, specificity, accuracy, positive coincidence rate, negative coincidence rate, misdiagnosis rate and missed diagnosis rate of CT in IFI were 92.18, 61.11, 85.37, 89.39, 68.75, 38.89 and 7.81%, respectively, while those of X-ray in IFI were 67.19, 72.22, 68.29, 89.58, 38.24, 27.78 and 32.81%, respectively. The sensitivity, accuracy and negative coincidence rate of CT in the diagnosis of IFI were significantly higher than those of X-ray (P<0.05), with a sensitivity of 92.18%, which indicates that CT has a higher diagnostic value in IFI. The results of CT combined with the basic condition of the patients can be used to initially diagnose pulmonary fungal infections, which is of high diagnostic value and can improve clinical treatment.

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.

Imaging of Pneumonias and Other Thoracic Complications After Hematopoietic Stem Cell Transplantation

Hematopoietic stem cell transplantation (HSCT) is used in the treatment of various oncologic and hematologic diseases. After HSCT, patients are immunocompromised and are at risk for a wide variety of infectious and noninfectious complications. CT is routinely used when pulmonary complications are suspected after HSCT. In this article, we review the CT appearance of pulmonary complications that occur in the post-transplantation period with special emphasis on opportunistic infections, many of which are life-threatening.

The halo sign: HRCT findings in 85 patients

Objective:

The halo sign consists of an area of ground-glass opacity surrounding pulmonary lesions on chest CT scans. We compared immunocompetent and immunosuppressed patients in terms of halo sign features and sought to identify those of greatest diagnostic value.

Methods:

This was a retrospective study of CT scans performed at any of seven centers between January of 2011 and May of 2015. Patients were classified according to their immune status. Two thoracic radiologists reviewed the scans in order to determine the number of lesions, as well as their distribution, size, and contour, together with halo thickness and any other associated findings.

Results:

Of the 85 patients evaluated, 53 were immunocompetent and 32 were immunosuppressed. Of the 53 immunocompetent patients, 34 (64%) were diagnosed with primary neoplasm. Of the 32 immunosuppressed patients, 25 (78%) were diagnosed with aspergillosis. Multiple and randomly distributed lesions were more common in the immunosuppressed patients than in the immunocompetent patients (p < 0.001 for both). Halo thickness was found to be greater in the immunosuppressed patients (p < 0.05).

Conclusions:

Etiologies of the halo sign differ markedly between immunocompetent and immunosuppressed patients. Although thicker halos are more likely to occur in patients with infectious diseases, the number and distribution of lesions should also be taken into account when evaluating patients presenting with the halo sign.

Early diagnosis of invasive mould infections and disease

Invasive mould infections (IMIs), such as invasive aspergillosis or mucormycosis, are a major cause of death in patients with haematological cancer and in patients receiving long-term immunosuppressive therapy. Early diagnosis and prompt initiation of antifungal therapy are crucial steps in the management of patients with IMI. The diagnosis of IMI remains a major challenge, with an increased spectrum of fungal pathogens and a diversity of clinical and radiological presentations within the expanding spectrum of immunocompromised hosts. Diagnosis is difficult to establish and is expressed on a scale of probability (proven, probable and possible). Imaging (CT scan), microbiological tools (direct examination, culture, PCR, fungal biomarkers) and histopathology are the pillars of the diagnostic work-up of IMI. None of the currently available diagnostic tests provides sufficient sensitivity and specificity alone, so the optimal approach relies on a combination of multiple diagnostic strategies, including imaging, fungal biomarkers (galactomannan and 1,3-β-d-glucan) and molecular tools. In recent years, the development of PCR for filamentous fungi (primarily Aspergillus or Mucorales) and the progress made in the standardization of fungal PCR technology, may lead to future advances in the field. The appropriate diagnostic approach for IMI should be individualized to each centre, taking into account the local epidemiology of IMI and the availability of diagnostic tests.

Role of HRCT Chest in Post Stem Cell Transplant Recipients Suspected of Pulmonary Complications

INTRODUCTION

Stem cell transplantation is today's procedure of choice for management of various hematopoietic malignant and severe immunogenic disorders. High Resolution Computed Tomography (HRCT) is a common technique for the diagnosis of pulmonary complications in stem cell transplant recipients. There are a large number of complications which can complicate the post-transplant period.

AIM

To study the role of HRCT chest in stem cell transplant patients developing pulmonary complications, detect any evidence of infection, detect clinical signs of lung infections, Graft versus Host Disease (GvHD) or other regimen related toxicities outlined earlier, detect any evidence of GvHD and correlate these clinical signs with radiological changes in the lungs.

MATERIALS AND METHODS

The study was a prospective study of 52 participants with indication of stem cell transplantation. The study included recipients of HSCT transplant and the exclusion criteria was patients who failed for engraftment and having an associated history of pulmonary embolism. Patients were screened for pre-transplant chemotherapy, clinical examination, laboratory investigations including blood and biochemical examinations, imaging by ultrasound, chest radiography, baseline HRCT and a follow-up for post-transplant infections and complications with 16 slice Siemens CT scan. Statistical analysis was done using Pearson's chi-squared test.

RESULTS

Four patients among the total 56 were excluded due to non-engraftment. The most common associated findings in decreasing order are (these patients died): consolidation, pancytopenia and gastrointestinal tract symptoms with VOD (Veno-Occlusive Disease). These findings were seen on HRCT as consolidation, cavities, ground glass opacities, fibrotic changes, bronchiectatic changes and tree in bud appearance.

CONCLUSION

The study highlights the significant positive findings on the HRCT which were missed on routine chest radiograph and can be used for early diagnoses. Thus, HRCT helped in decreasing the mortality. The abnormal vitals and TLC counts showed a significant relation between the numbers of death in the study.

Lower Respiratory Tract Infections

This review will focus on the infectious etiologies and more common noninfectious causes of lower respiratory tract syndromes among major immunosuppressed populations. The changing epidemiology of infections in the era of highly active antiretroviral therapy (HAART) in the case of HIV-positive patients and the impacts of both newer immune-suppressant therapies and anti-infective prophylaxis for other immunocompromised hosts will be discussed, with emphasis on diagnostic approaches and practice algorithms.

Clinical characteristics and computed tomography findings of pulmonary toxoplasmosis after hematopoietic stem cell transplantation

The prognosis of pulmonary toxoplasmosis, including disseminated toxoplasmosis involving the lungs, following hematopoietic stem cell transplantation (HSCT) is extremely poor due to the difficulties associated with early diagnosis and the rapidly progressive deterioration of multiorgan function. In our institution, we identified nine cases of toxoplasmosis, representing incidences of 2.2 and 19.6 % among all HSCT recipients and seropositive HSCT recipients, respectively. Of the patients with toxoplasmosis, six had pulmonary toxoplasmosis. Chest computed tomography (CT) findings revealed centrilobular, patchy ground-glass opacities (n = 3), diffuse ground-glass opacities (n = 2), ground-glass opacities with septal thickening (n = 1), and marked pleural effusion (n = 1). All cases died, except for one with suspected pulmonary toxoplasmosis who was diagnosed by a polymerase chain reaction assay 2 days after the onset of symptoms. In pulmonary toxoplasmosis, CT findings are non-specific and may mimic pulmonary congestion, atypical pneumonia, viral pneumonitis, and bronchopneumonia. Early diagnosis and treatment is crucial for overcoming this serious infectious complication. Pulmonary toxoplasmosis should be considered during differential diagnosis in a recipient with otherwise unexplained signs of infection and CT findings with ground-glass opacities, regardless of the distribution.

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.

Current Indications, Techniques, and Imaging Findings of Stem Cell Treatment and Bone Marrow Transplant

The role of stem cell therapy in the treatment of hematologic and nonhematologic conditions is ever increasing. A thorough knowledge of the applications of stem cells and transplant physiology is essential for understanding the imaging manifestations. Stem cell imaging includes molecular imaging, and diagnostic and interventional radiology. It is possible to make a diagnosis of various complications and diseases associated with stem cell transplant. This article presents a simplified overview of stem cell applications and techniques with focus on hematopoietic stem cell transplant imaging.

Diagnostics and susceptibility testing in Aspergillus

Invasive aspergillosis is a major cause of morbidity and mortality in immunosuppressed patients. Early diagnosis and correct antifungal treatment have a direct impact on patient survival. A number of newer diagnostic procedures have been developed as alternatives to conventional microbiological methods. The detection of fungal components, largely antigens and DNA, are used in clinical laboratories to diagnose invasive aspergillosis. Other rapid diagnostic tests have been recently developed with promising results. However, antifungal resistance is becoming an emerging problem. The detection of this resistance is important to administer the proper antifungal agent. This text reviews the novelties on new diagnostics Aspergillus spp.

PROCEDURES

Intrinsic antifungal resistance and mechanisms of secondary resistance to triazoles in A. fumigatus are also reviewed.

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.

A Case of Rapid Exacerbation of Pulmonary Mycobacterium Avium Complex Infection Mimicking Pulmonary Aspergillosis

We herein report a case of pulmonary Mycobacterium avium complex (MAC) infection with pulmonary multiple nodules and the "halo sign" on chest computed tomography (CT) in which the patient showed rapid exacerbation seven years after undergoing bone marrow transplantation (BMT). A 68-year-old Japanese female visited our hospital due to a productive cough and dyspnea. She had undergone allogeneic BMT for acute myelocytic leukemia and received both prednisolone (2 mg/day) and cyclosporine (30 mg/day). Chest CT demonstrated no abnormal findings on admission; however, multiple pulmonary nodules and the "halo sign" were detected three weeks later. Although a fungal infection was initially suspected, a bronchoscopic examination revealed pulmonary MAC infection. In the present case, pulmonary MAC infection exhibited rapid progression with unique CT findings. Physicians should consider MAC infection in the differential diagnosis in patients who receive BMT and/or immunosuppressive agents, even if the clinical and radiological findings are atypical of the disease.

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.

British Society for Medical Mycology best practice recommendations for the diagnosis of serious fungal diseases

Invasive fungal diseases are an important cause of morbidity and mortality in a wide range of patients, and early diagnosis and management are a challenge. We therefore did a review of the scientific literature to generate a series of key recommendations for the appropriate use of microbiological, histological, and radiological diagnostic methods for diagnosis of invasive fungal diseases. The recommendations emphasise the role of microscopy in rapid diagnosis and identification of clinically significant isolates to species level, and the need for susceptibility testing of all Aspergillus spp, if treatment is to be given. In this Review, we provide information to improve understanding of the importance of antigen detection for cryptococcal disease and invasive aspergillosis, the use of molecular (PCR) diagnostics for aspergillosis, and the crucial role of antibody detection for chronic and allergic aspergillosis. Furthermore, we consider the importance of histopathology reporting with a panel of special stains, and emphasise the need for urgent (<48 hours) and optimised imaging for patients with suspected invasive fungal infection. All 43 recommendations are auditable and should be used to ensure best diagnostic practice and improved outcomes for patients.

Diagnosis and antimicrobial therapy of lung infiltrates in febrile neutropenic patients (allogeneic SCT excluded): updated guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO)

Up to 25% of patients with profound neutropenia lasting for >10 days develop lung infiltrates, which frequently do not respond to broad-spectrum antibacterial therapy. While a causative pathogen remains undetected in the majority of cases, Aspergillus spp., Pneumocystis jirovecii, multi-resistant Gram-negative pathogens, mycobacteria or respiratory viruses may be involved. In at-risk patients who have received trimethoprim-sulfamethoxazole (TMP/SMX) prophylaxis, filamentous fungal pathogens appear to be predominant, yet commonly not proven at the time of treatment initiation. Pathogens isolated from blood cultures, bronchoalveolar lavage (BAL) or respiratory secretions are not always relevant for the etiology of pulmonary infiltrates and should therefore be interpreted critically. Laboratory tests for detecting Aspergillus galactomannan, β-D-glucan or DNA from blood, BAL or tissue samples may facilitate the diagnosis; however, most polymerase chain reaction assays are not yet standardized and validated. Apart from infectious agents, pulmonary side-effects from cytotoxic drugs, radiotherapy or pulmonary involvement by the underlying malignancy should be included into differential diagnosis and eventually be clarified by invasive diagnostic procedures. Pre-emptive treatment with mold-active systemic antifungal agents improves clinical outcome, while other microorganisms are preferably treated only when microbiologically documented. High-dose TMP/SMX is first choice for treatment of Pneumocystis pneumonia, while cytomegalovirus pneumonia is treated primarily with ganciclovir or foscarnet in most patients. In a considerable number of patients, clinical outcome may be favorable despite respiratory failure, so that intensive care should be unrestrictedly provided in patients whose prognosis is not desperate due to other reasons.

Imaging of Pulmonary Infections

Pulmonary infection is one of the most frequent causes of morbidity and mortality throughout the world. Many infections occur in individuals with concomitant intrapulmonary or extrathoracic diseases; however, they commonly develop in otherwise healthy people. In the non-immunocompromised population, pneumonia is the most prevalent community-acquired infection and the second most common nosocomial infectious disorder. In immunocompromised patients, in children, and in the elderly, pneumonia, as well as other pulmonary infections, may develop into a life-threatening condition.

How we treat invasive fungal diseases in patients with acute leukemia: the importance of an individualized approach

Invasive fungal diseases (IFDs) represent an important cause of treatment failure in adults with acute leukemia. Because of leukemia’s heterogeneity, the risk for IFDs is highly variable. We therefore apply a risk-adapted antifungal strategy with strong emphasis on pretreatment and day-15 posttreatment to allow earlier and more individualized interventions. We determine pretreatment risks for IFDs based on 4 factors: (1) host fitness for standard therapy (ie, fit, unfit, or frail); (2) leukemia resistance (high vs low probability of achieving complete remission [CR]); (3) anticipated treatment-related toxicity such as neutropenia, mucositis, and steroid-induced immunosuppression; and (4) patient exposure to opportunistic fungi. Accordingly, we stratify patients as high, intermediate, or low risk for IFDs and apply risk-adapted antifungal strategies, including primary or secondary prophylaxis and diagnostic-based preemptive or empiric therapy. Prevention of IFDs also relies on optimizing organ function, decreasing exposure to opportunistic fungi, and improving net state of immunosuppression with use of better-tolerated and investigational agents for unfit patients and those with adverse leukemia biology. Novel targeted and safe therapies that can achieve higher rates of sustained CR among patients with adverse genetics offer the best promise for reducing the burden of IFDs in these patients.

Imaging of complications from hematopoietic stem cell transplant

Stem cell transplant has been the focus of clinical research for a long time given its potential to treat several incurable diseases like hematological malignancies, diabetes mellitus, and neuro-degenerative disorders like Parkinson disease. Hematopoietic stem cell transplantation (HSCT) is the oldest and most widely used technique of stem cell transplant. HSCT has not only been used to treat hematological disorders including hematological malignancies, but has also been found useful in treamtent of genetic, immunological, and solid tumors like neuroblastoma, lymphoma, and germ cell tumors. In spite of the rapid advances in stem cell technology, success rate with this technique has not been universal and many complications have also been seen with this form of therapy. The key to a successful HSCT therapy lies in early diagnosis and effective management of complications associated with this treatment. Our article aims to review the role of imaging in diagnosis and management of stem cell transplant complications associated with HSCT.

High-resolution CT can differentiate between alloimmune and nonalloimmune lung disease early after hematopoietic cell transplantation

OBJECTIVE

The purpose of this study was to develop a simple semiquantitative high-resolution CT (HRCT) scoring system to differentiate alloimmune-mediated lung syndromes (allo-LS) from other lung diseases early after hematopoietic cell transplantation. Allo-LS should be differentiated from other abnormalities, such as infections and toxicity, because they are life threatening and require prompt and specific treatment.

MATERIALS AND METHODS

In 52 pediatric hematopoietic cell transplant recipients with early symptoms of pulmonary disease, a clinical diagnosis was made by an expert physician. HRCT studies were scored by two independent radiologists for various airway and parenchyma abnormalities. HRCT scores were compared with the final clinical diagnoses.

RESULTS

Patients with allo-LS had significantly higher HRCT severity scores for ground-glass pattern and airtrapping compared with patients with nonalloimmune disease. A combined score was constructed (the "allo-score") that appeared to have good predictive capacity for clinical allo-LS (AUC = 0.82). HRCT scoring was reproducible for all items except airway wall thickening and septal thickening.

CONCLUSION

A simple HRCT severity score can be helpful to differentiate allo-LS from other pulmonary complications early after hematopoietic cell transplantation.

An unusual case of disseminated toxoplasmosis in a previously healthy pregnant patient: radiographic, CT, and MRI findings

Toxoplasmosis is a ubiquitous protozoal infection that during pregnancy commonly affects the fetus severely, with maternal infection usually being mild self-limiting. Disseminated toxoplasmosis in a healthy pregnant woman has, to the best of our knowledge, not been reported before. We present a case of disseminated toxoplasmosis involving pulmonary, central nervous system, and lymph nodes in a pregnant woman and imaging findings on radiography, computed tomography, and magnetic resonance imaging.

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.

Role of HRCT in detection and characterization of pulmonary abnormalities in patients with febrile neutropenia

Background:

Fever is of grave concern in the management of patients with neutropenia with early detection of a focus of infection being the major goal. As lungs are the most common focus, chest imaging is of vital importance. This Institute Review Board approved prospective study was undertaken to assess the usefulness of high resolution computed tomography (HRCT) in early detection and characterization of pulmonary abnormalities in febrile neutropenia.

Materials and Methods:

A total of 104 consecutive patients (M:F:75:29, age range 11–66 years) with fever of 38.2°C or more with an absolute neutrophil count <500/μl underwent HRCT chest. HRCT diagnosis was compared with final diagnosis based on ancillary investigations.

Results:

HRCT could detect pulmonary abnormalities in 93 patients (89.4%) with air space consolidation being the predominant finding (n = 57), followed by ground-glass opacities (Ground glass opacity (GGO), n = 49) and nodules (n = 39). HRCT could correctly characterize the infective lesions in 76 patients (81.7%). Presence of random or pleural-based nodules >10 mm with or without surrounding GGO or cavitations was sensitive (95.23%) and specific (96.7%) for fungal infection, while small (1–4 mm) random or centrilobular nodules with tree-in-bud appearance was sensitive (90%) and highly specific (97.02%) for tuberculosis. Diagnosis of pyogenic infection based on presence of air-space consolidation, pleural effusion, GGO or centrilobular nodules showed a sensitivity of 84.78% and specificity of 93.84%, whereas patchy or diffuse GGO, interstitial thickening and/or air-space consolidation showed high sensitivity (86.7%) and specificity (96.8%) for Pneumocystis jiroveci pneumonia.

Conclusion:

HRCT chest is an excellent modality in the diagnostic work-up of patients with febrile neutropenia allowing early detection and characterization of pulmonary abnormalities.

[Examination of late pulmonary toxicity in children treated for malignancies]

INTRODUCTION

The present investigation was based on a survey in 2005, in which the authors found pulmonary function abnormalities in survivors of childhood cancer, who were treated with anticancer therapy.

AIM

The purpose of the present study was to follow-up childhood cancer survivors and detect late pulmonary toxicity.

PATIENTS AND METHODS

Lung function test was performed with spirometry in 26 survivors participated in this study (10 females and 16 males; mean age, 19.4 years at the time of the second follow-up evaluation). The average time periods from treatment until the first and second follow-up evaluation were 4.5 and 10 years, respectively.

RESULTS

The authors found 14 patients with pathological pulmonary function tests results at the time of the first follow-up evaluation, from which 7 patients had obstructive, 5 patients had mixed and 2 patients had restrictive abnormalities. However, there were only 6 patients who had abnormal pulmonary function at the time of the second follow-up evaluation (2 patients with obstructive and 4 patients with restrictive pulmonary function tests (p<0.05).

CONCLUSION

Restrictive pulmonary disorder was detected in only small part of the treated patients. The obstructive pulmonary abnormalities caused by the treatment showed an improving tendency over time.

Early implementation of antifungal therapy in the management of febrile neutropenia is associated with favourable outcome during induction chemotherapy for acute leukaemias

BACKGROUND

Mortality related to induction chemotherapy during the treatment of acute leukaemias (AL) has been estimated at 5-20%, and this increases with age. Fungal infection remains one of the major causes of morbidity and mortality and is considered an obstacle to the successful management of acute leukaemias.

METHODS

We retrospectively analysed all patients treated for acute leukaemias at a single institution between July 2006 and January 2009, to assess the impact of early antifungal therapy on outcome during induction chemotherapy. There were 44 episodes of induction chemotherapy, with a median age of patients of 61 years (range 18-81), including 29 patients with acute myeloid leukaemia, 9 with acute lymphoblastic leukaemia and 6 with relapsed AL. The median age was 61 years (range 18-81), and 20 patients were over the age of 60 years.

RESULTS

All patients who developed febrile neutropenia received broad-spectrum antibiotics. Early empirical antifungal treatment was commenced with voriconazole (15 patients) or caspofungin (12 patients) if the febrile neutropenia did not resolve after 72 h of antibiotic therapy, in conjunction with radiological changes consistent with possible fungal infection. None of the patients succumbed during induction chemotherapy. The 120-day mortality rate after the induction therapy was 2.2%, without any incidence of invasive fungal disease.

CONCLUSION

Our analysis shows that early empirical treatment for fungal infection with voriconazole or caspofungin is associated with a favourable outcome of induction therapy for acute leukaemias. Further studies to confirm this finding are warranted.

How I manage pulmonary nodular lesions and nodular infiltrates in patients with hematologic malignancies or undergoing hematopoietic cell transplantation

Pulmonary nodules and nodular infiltrates occur frequently during treatment of hematologic malignancies and after hematopoietic cell transplantation. In patients not receiving active immunosuppressive therapy, the most likely culprits are primary lung cancer, chronic infectious or inactive granulomata, or even the underlying hematologic disease itself (especially in patients with lymphoma). In patients receiving active therapy or who are otherwise highly immunosuppressed, there is a wider spectrum of etiologies with infection being most likely, especially by bacteria and fungi. Characterization of the pulmonary lesion by high-resolution CT imaging is a crucial first diagnostic step. Other noninvasive tests can often be useful, but invasive testing by bronchoscopic evaluation or acquisition of tissue by one of several biopsy techniques should be performed for those at risk for malignancy or invasive infection unless contraindicated. The choice of the optimal biopsy technique should be individualized, guided by location of the lesion, suspected etiology, skill and experience of the diagnostic team, procedural risk of complications, and patient status. Although presumptive therapy targeting the most likely etiology is justified in patients suspected of serious infection while evaluation proceeds, a structured evaluation to determine the specific etiology is recommended. Interdisciplinary teamwork is highly desirable to optimize diagnosis and therapy.

Human metapneumovirus (HMPV) associated pulmonary infections in immunocompromised adults--initial CT findings, disease course and comparison to respiratory-syncytial-virus (RSV) induced pulmonary infections

AIM

To describe computed tomography (CT)-imaging findings in human metapneumovirus (HMPV)-related pulmonary infection as well as their temporal course and to analyze resemblances/differences to pulmonary infection induced by the closely related respiratory-syncytial-virus (RSV) in immunocompromised patients.

MATERIALS AND METHODS

Chest-CT-scans of 10 HMPV PCR-positive patients experiencing pulmonary symptoms were evaluated retrospectively with respect to imaging findings and their distribution and results were then compared with data acquired in 13 patients with RSV pulmonary infection. Subsequently, we analyzed the course of chest-findings in HMPV patients.

RESULTS

In HMPV, 8/10 patients showed asymmetric pulmonary findings, whereas 13/13 patients with RSV-pneumonia presented more symmetrical bilateral pulmonary infiltrates. Image analysis yielded in HMPV patients following results: ground-glass-opacity (GGO) (n=6), parenchymal airspace consolidations (n=5), ill-defined nodular-like centrilobular opacities (n=9), bronchial wall thickening (n=8). In comparison, results in RSV patients were: GGO (n=10), parenchymal airspace consolidations (n=9), ill-defined nodular-like centrilobular opacities (n=10), bronchial wall thickening (n=4). In the course of the disease, signs of acute HMPV interstitial pneumonia regressed transforming temporarily in part into findings compatible with bronchitis/bronchiolitis.

CONCLUSIONS

Early chest-CT findings in patients with HMPV-related pulmonary symptoms are compatible with asymmetric acute interstitial pneumonia accompanied by signs of bronchitis; the former transforming with time into bronchitis and bronchiolitis before they resolve. On the contrary, RSV-induced pulmonary infection exhibits mainly symmetric acute interstitial pneumonia.

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.