Fat Embolism Syndrome: Lung Computed Tomography Findings in 18 Patients

OBJECTIVE

The purpose of this study was to evaluate the lung computed tomography (CT) findings in fat embolism (FE) syndrome.

METHODS

We retrospectively evaluated 19 CT examinations of 18 patients with FE syndrome, diagnosed clinically using the Gurd and Wilson criteria.

RESULT

Fat embolism syndrome showed 3 patterns: negative examination, bilateral interstitial-alveolar involvement, and adult respiratory distress syndrome like. Frequent findings included consolidations (17 patients), mostly with gravity dependent distribution, and ground-glass opacities (17 patients), mostly with patchy distribution. Fifteen patients showed an overlapping random nodular pattern. Less common findings included lobular ground-glass opacities and lobular consolidations, smooth septal thickening, thickening of the bronchial wall, and areas of crazy paving. The extension of the consolidations correlates with the duration of assisted ventilation.

CONCLUSIONS

In FE syndrome, pulmonary CT findings are ground-glass opacities and dependent consolidations, associated with other variably overlapping signs, such as lobular opacities, random nodules, septal thickening, and bronchial wall thickening.

Viral Pneumonia in Patients with Hematologic Malignancy or Hematopoietic Stem Cell Transplantation

Viral pneumonias in patients with hematologic malignancies and recipients of hematopoietic stem cell transplantation cause significant morbidity and mortality. Advances in diagnostic techniques have enabled rapid identification of respiratory viral pathogens from upper and lower respiratory tract samples. Lymphopenia, myeloablative and T-cell depleting chemotherapy, graft-versus-host disease, and other factors increase the risk of developing life-threatening viral pneumonia. Chest imaging is often nonspecific but may aid in diagnoses. Bronchoscopy with bronchoalveolar lavage is recommended in those at high risk for viral pneumonia who have new infiltrates on chest imaging.

Clinical Features and Radiological Findings of Adenovirus Pneumonia Associated with Progression to Acute Respiratory Distress Syndrome: A Single Center Study in 19 Adult Patients

Objective

To describe radiologic findings of adenovirus pneumonia and to understand clinico-radiological features associated with progression to acute respiratory distress syndrome (ARDS) in patients with adenovirus pneumonia.

Materials and Methods

This study included 19 patients diagnosed with adenovirus pneumonia at a tertiary referral center, in the period between March 2003 and April 2015. Clinical findings were reviewed, and two radiologists assessed imaging findings by consensus. Chi-square, Fisher's exact, and Student's t tests were used for comparing patients with and without subsequent development of ARDS.

Results

Of 19 patients, nine were immunocompromised, and 10 were immunocompetent. Twelve patients (63%) progressed to ARDS, six of whom (32%) eventually died from the disease. The average time for progression to ARDS from symptom onset was 9.6 days. Initial chest radiographic findings were normal (n = 2), focal opacity (n = 9), or multifocal or diffuse opacity (n = 8). Computed tomography (CT) findings included bilateral (n = 17) or unilateral (n = 2) ground-glass opacity with consolidation (n = 14) or pleural effusion (n = 11). Patients having subsequent ARDS had a higher probability of pleural effusion and a higher total CT extent compared with the non-ARDS group (p = 0.010 and 0.007, respectively). However, there were no significant differences in clinical variables such as patient age and premorbid condition.

Conclusion

Adenovirus pneumonia demonstrates high rates of ARDS and mortality, regardless of patient age and premorbid conditions, in the tertiary care setting. Large disease extent and presence of pleural effusion on CT are factors suggestive of progression to ARDS.

Early chest computed tomography in adult acute severe community-acquired pneumonia patients treated in the intensive care unit

BACKGROUND

The value of early chest computed tomography (CT) was evaluated among severe community-acquired pneumonia (SCAP) patients.

METHODS

The study population consisted of 65 of 457 SCAP patients with concomitant chest CT and radiograph performed within 48 h of ICU admission. Each image pair was re-evaluated by two radiologists. The type of pneumonia, the presence of pleural fluid and atelectasis were assessed. Therapeutic and diagnostic procedures induced by CT results were analysed together with clinical, microbiological and outcome data.

RESULTS

Alveolar pneumonia was observed in 72.3% of patients by radiograph and in 75.4% of patients by CT. Pleural fluid was detected via chest radiograph and CT in 17 (26.2%) and 41 cases (63.1%), (P < 0.001) and atelectasis in 10 (15.4%) and 22 cases (33.8%), (P = 0.002), respectively. In 34 patients (52.3%), the CT revealed 38 new findings (58.5%) not shown in plain chest radiograph. Out of these 34 patients, therapeutic interventions or procedures were performed in 26 (76.5%). The number of infected lobes correlated negatively with the lowest PaO2 /FiO2 ratio (ρ = -0.326, P = 0.008) for chest CT scans.

CONCLUSION

Compared with chest radiograph, chest CT generated new findings in nearly 60% of SCAP patients, leading to new procedures or changes in medical treatment in nearly 75% of those patients. Chest CT better describes the pulmonary involvement and severity of oxygenation disorder compared to a plain chest radiograph.

Severe Pneumonia Treated Succesfully with Levofloxacin and Oseltamivir During Flu Epidemic

Viral pneumonia is an important cause of community acquired pneumonias (CAP). It's not only specific to childhood period. Although immunocompromised adults are susceptible; all young and healthy adults are at risk. Viral pneumonias are usually underestimated due to lack of diagnostic modalities so a clinician must be aware of. Co-infection of viruses and bacteria is not uncommon and can be mortal especially in a flu epidemic, therefore, in the absence of diagnostic tools initiating to anti-viral treatment without delay is important.

Middle East Respiratory Syndrome Coronavirus: What Does a Radiologist Need to Know?

OBJECTIVE

The overarching goal of this article is to provide radiologists with the most up-to-date information regarding the underlying epidemiology, pathophysiology, clinical features, and imaging findings related to Middle East respiratory syndrome coronavirus (MERS-CoV), a potentially deadly new infection.

CONCLUSION

An increased awareness of MERS-CoV and an understanding of the radiologic features of MERS-CoV can improve the early assessment and monitoring of this new infection. Radiologists can provide information based on chest radiographic and CT scores that can be helpful for patient management and predicting prognosis.

Pulmonary Infections: Imaging with CT

Computed tomography (CT) plays a key role in various kinds of pulmonary infections especially in immunocompromised patients, owing to its much higher sensitivity and specificity than the traditionally performed chest X-ray. CT permits the detection of the main infectious pattern and associated findings with high confidence and allows for the precise assessment of all involved structures, to potentially guide a bronchoalveolar lavage or another diagnostic procedure, and to ensure a reliable follow-up. It may be performed at a carefully chosen dose, which may nearly reach that of a chest X-ray in specific situations. The importance of post-processing tools is undeniable in some conditions, in particular for the evaluation of micronodules in the immunocompromised population. The wide spectrum of features of specific organisms according to the immune status, such as in aspergillosis or tuberculosis, must be known, as well as the potential of atypical presentations in case of Pneumocystis jirovecii (PCP) pneumonia when occurring in non-HIV immunocompromised patients. In all cases, underlying disorders must be considered as well as all the differential diagnoses. Overall, CT definitely helps clinicians to diagnose pulmonary infections and to make treatment decisions, especially in vulnerable patients.

Thoracic lymphadenopathy in benign diseases: A state of the art review

Lymphadenopathy is a common radiological finding in many thoracic diseases and may be caused by a variety of infectious, inflammatory, and neoplastic conditions. This review aims to describe the patterns of mediastinal and hilar lymphadenopathy found in benign diseases in immunocompetent patients. Computed tomography is the method of choice for the evaluation of lymphadenopathy, as it is able to demonstrate increased size of individual nodes, abnormalities of the interface between the mediastinum and lung, invasion of surrounding fat, coalescence of adjacent nodes, obliteration of the mediastinal fat, and hypo- and hyperdensity in lymph nodes. Intravenous contrast enhancement may be needed to help distinguish nodes from vessels. The most frequent infections resulting in this finding are tuberculosis and fungal disease (particularly histoplasmosis and coccidioidomycosis). Sarcoidosis is a relatively frequent cause of lymphadenopathy in young adults, and can be distinguished from other diseases - especially when enlarged lymph nodes are found to be multiple and symmetrical. Other conditions discussed in this review are silicosis, drug reactions, amyloidosis, heart failure, Castleman's disease, viral infections, and chronic obstructive pulmonary disease.

Infection

Community-Acquired Pneumonia (CAP) is the first leading cause of death due to infection worldwide.Many gram-positive, gram-negative bacteria, funguses and viruses can cause the infectious pulmonary disease, and the severity of pneumonia depends on the balance between the microorganism charge, the body immunity defenses and the quality of the underlying pulmonary tissue. The microorganisms may reach the lower respiratory tract from inhaled air or from infected oropharyngeal secretions. The same organism may produce several different patterns that depend on the balance between the microorganism charge and the body immunity defenses.CAP is classified into three main groups: lobar pneumonia, bronchopneumonia and interstitial pneumonia.Lobar pneumonia is characterized by the filling of alveolar spaces by edema full of white and inflammatory cells. Necrotizing pneumonia consists of a fulminant process associated with focal areas of necrosis that results in abscesses. Bronchopneumonia or lobular pneumonia, is characterized by a peribronchiolar inflammation with thickening of peripheral bronchial wall, the diffusion of inflammation to the centrilobular alveolar spaces and development of nodules.The interstitial pneumonia represents with the destruction and esfoliation of the respiratory ciliated and mucous cells. The interstitial septa, the bronchial and bronchiolar walls become thickened for the inflammation process and lymphocytes interstitial infiltrates.Chest radiography represents an important initial examination in all patients suspected of having pulmonary infection and for monitoring response to therapy.Its role is to identify the pulmonary opacities, their internal characteristics and distribution, pleural effusion and presence of other complications as abscesses and pneumothorax.High spatial CT resolution allows accurate assessment of air space inflammation.The CT findings include nodules, interlobular septal thickening, intralobular reticular opacities, ground-glass opacities, tree-in-bud pattern, lobar-segmental consolidation, lobular consolidation, abscesses, pneumatocele, pleural effusion, pericardial effusion, mediastinal and hilar lymphoadenopaties, airway dilatation and emphysema.

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.

Comparison of the pathogenesis of the highly passaged MCMV Smith strain with that of the low passaged MCMV HaNa1 isolate in BALB/c mice upon oronasal inoculation

Murine cytomegalovirus (MCMV) Smith strain is widely used in mouse models to study HCMV infections. Due to high serial passages, MCMV Smith has acquired genetic and biological changes. Therefore, a low passaged strain would be more relevant to develop mouse models. Here, the pathogenesis of an infection with MCMV Smith was compared with that of an infection with a low passaged Belgian MCMV isolate HaNa1 in BALB/c adult mice following oronasal inoculation with either a low (10⁴ TCID₅₀/mouse) or high (10⁶ TCID₅₀/mouse) inoculation dose. Both strains were mainly replicating in nasal mucosa and submandibular glands for one to two months. In nasal mucosa, MCMV was detected earlier and longer (1–49 days post inoculation (dpi)) and reached higher titers with the high inoculation dose compared to the low inoculation dose (14–35 dpi). In submandibular glands, a similar finding was observed (high dose: 7–49 dpi; low dose: 14–42 dpi). In lungs, both strains showed a restricted replication. In spleen, liver and kidneys, only the Smith strain established a productive infection. The infected cells were identified as olfactory neurons and sustentacular cells in olfactory epithelium, macrophages and dendritic cells in NALT, acinar cells in submandibular glands, and macrophages and epithelial cells in lungs for both strains. Antibody analysis demonstrated for both strains that IgG_2a was the main detectable antibody subclass. Overall, our results show that significant phenotypic differences exist between the two strains. MCMV HaNa1 has been shown to be interesting for use in mouse models in order to get better insights for HCMV infections in immunocompetent humans.

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.

Morphologic predictors of a microbiological yield in patients with a tree-in-bud pattern on computed tomography

PURPOSE

To evaluate the computed tomographic (CT) predictors of a clinically significant yield from microbiological tests in patients with a tree-in-bud pattern.

MATERIALS AND METHODS

CT examinations in 53 patients (male=34; mean age=52.9 ± 17.3 y) with a tree-in-bud pattern in whom a diagnostic test (sputum analysis, bronchoalveolar lavage or nasopharyngeal aspirates) had been performed within 2 weeks were identified. The following CT patterns were independently quantified by 2 thoracic radiologists: tree-in-bud, bronchiectasis, bronchial wall thickening, consolidation, ground-glass opacification, and nodules. The presence of cavitation (in nodules and/or consolidation) was recorded. Patient charts were reviewed for the presence of a clinically significant positive microbiological result.

RESULTS

A clinically significant causal organism was present in 25/53 (47%) patients. The median extent of a tree-in-bud pattern was 5 [range=1 to 16 (maximum range=0 to 18)], and cavitation was present in 14/53 (26%) patients (cavitating nodules=8, cavitation in consolidation=3, and cavitation in consolidation and nodules=3). There was no independent linkage between the extent of a tree-in-bud pattern and the identification of a clinically significant organism. The microbiological yield was significantly higher if there was coexistent cavitation in nodules or consolidation [11/14 (79%) vs. 14/39 (39%); P=0.005]. On stepwise logistic regression, the only CT predictor of a clinically significant microbiological yield was cavitation on CT (odds ratio=9.7; 95% confidence interval=1.9, 49.9; P<0.01); the extent of a tree-in-bud pattern, concurrent use of antibiotics, age, and sex were not independently linked to a significant microbiological yield.

CONCLUSIONS

A specific clinically significant microbiological diagnosis was obtained in approximately 50% of patients with a tree-in-bud pattern. The microbiological yield rises strikingly when a tree-in-bud pattern coexists with cavitation (in nodules or consolidation) but is not predicted by ancillary CT signs or clinical parameters.

Imaging infection

Thoracic imaging is widely used to detect lower respiratory tract infections, identify their complications, and aid in differentiating infectious from noninfectious thoracic disease. Less commonly, the combination of imaging findings and a clinical setting can favor infection with a specific organism. This confluence can occur in cases of bronchiectatic nontuberculous mycobacterial infections in immune-competent hosts, invasive fungal disease among neutropenic patients, Pneumocystis jiroveci pneumonia in patients with AIDS, and in cytomegalovirus infections in patients with recent hematopoietic cell transplantation. These specific diagnoses often depend on computed tomography scanning rather than chest radiography alone.

Comparison of chest-CT findings of Influenza virus-associated pneumonia in immunocompetent vs. immunocompromised patients

PURPOSE

To retrospectively compare CT-patterns of pulmonary infiltration caused by different Influenza virus types and subtypes in immunocompetent and immunocompromised patients for possible discrimination.

MATERIALS AND METHODS

Retrospective database search at our institution yielded 237 patients who were tested positive for Influenza virus type A or type B by bronchoalveolar lavage between January 2009 and April 2014. Fifty-six of these patients (female 26; male 30; median age 55.8 y, range 17-86 y; SD ± 14.4 y) underwent chest-HRCT due to a more severe clinical course of pulmonary infection. We registered all CT-findings compatible with pulmonary infection classifying them as airway predominant (tree-in-bud, centrilobular nodules, bronchial wall thickening ± peribronchial ground-glass opacity and consolidation) vs. interstitial-parenchymal predominant (bilateral, symmetrical GGO, consolidation, crazy paving and/or interlobular septal thickening). Twenty-six patients (46.4%) had follow-up CT-studies (0.78 mean, SD ± 5.8 scans).

RESULTS

Thirty-six patients were immunocompromised (group I) whereas 20 patients were immunocompetent (group II). An airway-centric pattern of infection was found in 15 patients (group I) and 14 patients (group II) whereas an interstitial-parenchymal predominant pattern was found in 14 patients (group I) and 2 patients (group II). Eleven patients had a mixed pattern with no clear assignment to one group. At FU, 12 patients from group I and 3 from group II showed transitional infiltration patterns: in 10 patients from interstitial-parenchymal into airway predominant pattern and in five patients from airway predominant into interstitial-parenchymal. No significant differences in the pattern of pulmonary infection were found between different types and subtypes of Influenza viruses.

CONCLUSION

Patterns of pulmonary infiltration caused by Influenza viruses do not significantly differ between immunocompetent and immunocompromised patients or between different types and subtypes of Influenza virus. One possible explanation for this could be the temporarily interchangeable character of pulmonary infiltration in this infection.

Chest HRCT findings in acute transformation of adult T-cell lymphoma/leukemia

OBJECTIVES

To assess chest high-resolution computed tomography (HRCT) findings in patients with acute transformation of adult T cell leukaemia/lymphoma (ATLL).

METHODS

We retrospectively identified 72 consecutive patients at our institution with ATLL between October 2000 and March 2014. The cases included acute type (n = 20), lymphoma type (n = 21), smouldering type (n = 24) and chronic type (n = 7). Sixteen (7 men, 9 women; aged 36-85 years, mean 63.3 years) of 31 patients (24 with smouldering and seven with chronic type; 51.6 %) developed acute transformation of ATLL, and had undergone chest HRCT examinations. Parenchymal abnormalities, enlarged lymph nodes, pericardial effusion, pleural effusion and skin lesions were evaluated on HRCT.

RESULTS

Chest HRCT of 15 of the 16 patients showed abnormal findings, including ground-glass opacity (GGO) (n = 8), consolidation (n = 5), interlobular septal thickening (n = 5) and nodules (n = 5). Pleural effusion was found in five patients, lymph node enlargement in 10 patients and multiple skin thickening in two patients.

CONCLUSIONS

Almost all patients with acute transformation of ATLL had abnormal findings on chest HRCT, which consisted mainly of lymph node enlargement, GGO, interlobular septal thickening, nodules and bilateral pleural effusions.

KEY POINTS

• The recognition of CT findings of acute transformation is important • Almost all patients with acute transformation have abnormal findings on HRCT • Characteristic CT features are present in acute transformation of indolent ATLL.

Predictors of viral pneumonia in patients with community-acquired pneumonia

BACKGROUND

Viruses are increasingly recognized as major causes of community-acquired pneumonia (CAP). Few studies have investigated the clinical predictors of viral pneumonia, and the results have been inconsistent. In this study, the clinical predictors of viral pneumonia were investigated in terms of their utility as indicators for viral pneumonia in patients with CAP.

METHODS

Adult patients (≥ 18 years old) with CAP, tested by polymerase chain reaction (PCR) for respiratory virus, at two teaching hospitals between October 2010 and May 2013, were identified retrospectively. Demographic and clinical data were collected by reviewing the hospital electronic medical records.

RESULTS

During the study period, 456 patients with CAP were identified who met the definition, and 327 (72%) patients were tested using the respiratory virus PCR detection test. Viral pneumonia (n = 60) was associated with rhinorrhea, a higher lymphocyte fraction in the white blood cells, lower serum creatinine and ground-glass opacity (GGO) in radiology results, compared to non-viral pneumonia (n = 250) (p < 0.05, each). In a multivariate analysis, rhinorrhea (Odd ratio (OR) 3.52; 95% Confidence interval (CI), 1.58-7.87) and GGO (OR 4.68; 95% CI, 2.48-8.89) were revealed as independent risk factors for viral pneumonia in patients with CAP. The sensitivity, specificity, positive- and negative-predictive values (PPV and NPV) of rhinorrhea were 22, 91, 36 and 83%: the sensitivity, specificity, PPV and NPV of GGO were and 43, 84, 40 and 86%, respectively.

CONCLUSION

Symptom of rhinorrhea and GGO predicted viral pneumonia in patients with CAP. The high specificity of rhinorrhea and GGO suggested that these could be useful indicators for empirical antiviral therapy.

Ultra-Low-Dose Chest CT in Patients with Neutropenic Fever and Hematologic Malignancy: Image Quality and Its Diagnostic Performance

Purpose

The aim of this study was to evaluate the image quality of ultra-low-dose computed tomography (ULDCT) and its diagnostic performance in making a specific diagnosis of pneumonia in febrile neutropenic patients with hematological malignancy.

Materials and Methods

ULDCT was performed prospectively in 207 febrile neutropenic patients with hematological malignancy. Three observers independently recorded the presence of lung parenchymal abnormality, and also indicated the cause of the lung parenchymal abnormality between infectious and noninfectious causes. If infectious pneumonia was considered the cause of lung abnormalities, they noted the two most appropriate diagnoses among four infectious conditions, including fungal, bacterial, viral, and Pneumocystis pneumonia. Sensitivity for correct diagnoses and receiver operating characteristic (ROC) curve analysis for evaluation of diagnostic accuracy were calculated. Interobserver agreements were determined using intraclass correlation coefficient.

Results

Of 207 patients, 139 (67%) had pneumonia, 12 had noninfectious lung disease, and 56 had no remarkable chest computed tomography (CT) (20 with extrathoracic fever focus and 36 with no specific disease). Mean radiation expose dose of ULDCT was 0.60±0.15 mSv. Each observer regarded low-dose CT scans as unacceptable in only four (1.9%), one (0.5%), and three (1.5%) cases of ULDCTs. Sensitivity and area under the ROC curve in making a specific pneumonia diagnosis were 63.0%, 0.65 for reader 1; 63.0%, 0.61 for reader 2; and 65.0%, 0.62 for reader 3; respectively

conclusion

ULDCT, with a sub-mSv radiation dose and acceptable image quality, provides ready and reasonably acceptable diagnostic information for pulmonary infection in febrile neutropenic patients with hematologic malignancy

Association of radiologic findings with mortality in patients with avian influenza H7N9 pneumonia

Background

The novel H7N9 virus causes severe illness, including pneumonia and acute respiratory distress syndrome, with high rates of mortality. We investigated the association of initial radiologic characteristics obtained at admission with clinical outcomes in patients with avian influenza H7N9 pneumonia.

Methods

Demographics, comorbidities, clinical findings, radiologic appearance and scores of the affected lung parenchyma were compared between survivor group (n = 15) and mortality group (n = 7). Two radiologic scores were calculated, one using chest radiography and one using CT. Follow-up CT scans at discharge were analyzed in 12 patients of the survival group.

Results

All the patients in mortality group developed acute respiratory distress syndrome and required mechanical ventilation, while in the survival group 33% (5/15) developed acute respiratory distress syndrome (P<0.05) and 27% (4/15) required mechanical ventilation (P<0.05). The mean radiographic and CT scores of the mortality group were 50% higher compared to the survival group (P<0.05). ROC analysis revealed an area under curve of 0.738 for the radiographic score with an optimal cutoff value of a score of 19 for prediction of mortality, with a sensitivity of 71% and a specificity of 67%, and an area under curve of 0.833 for the CT score with an optimal cutoff value of a CT score of 21 for prediction of mortality, with a sensitivity of 86% and a specificity of 73%. The mean CT score of the affected lung parenchyma at discharge was 30% lower than the initial CT examination (P<0.05).

Conclusion

High initial radiologic score is associated with mortality in patients with avian influenza H7N9 pneumonia.

Nodular inflammatory foci are sites of T cell priming and control of murine cytomegalovirus infection in the neonatal lung

Neonates, including mice and humans, are highly susceptible to cytomegalovirus (CMV) infection. However, many aspects of neonatal CMV infections such as viral cell tropism, spatio-temporal distribution of the pathogen as well as genesis of antiviral immunity are unknown. With the use of reporter mutants of the murine cytomegalovirus (MCMV) we identified the lung as a primary target of mucosal infection in neonatal mice. Comparative analysis of neonatal and adult mice revealed a delayed control of virus replication in the neonatal lung mucosa explaining the pronounced systemic infection and disease in neonates. This phenomenon was supplemented by a delayed expansion of CD8⁺ T cell clones recognizing the viral protein M45 in neonates. We detected viral infection at the single-cell level and observed myeloid cells forming “nodular inflammatory foci” (NIF) in the neonatal lung. Co-localization of infected cells within NIFs was associated with their disruption and clearance of the infection. By 2-photon microscopy, we characterized how neonatal antigen-presenting cells (APC) interacted with T cells and induced mature adaptive immune responses within such NIFs. We thus define NIFs of the neonatal lung as niches for prolonged MCMV replication and T cell priming but also as sites of infection control.

Neonates are highly susceptible to a number of infections that usually cause disease only in immunocompromised individuals, most likely because of their incompletely developed immune system. Although this phenomenon has been frequently observed, immune responses of neonates remain largely undefined upon infections with viruses. There is lack of knowledge about the spatio-temporal dynamics of host-virus interaction, especially in comparative infection models of neonates and adults. In this study, with the use of virus reporter mutants, we provide elaborate insight into these aspects in the mouse model of CMV infection. We define hallmarks of virus tropism, early cellular immune responses and general infection dynamics, findings that are fundamental to understand neonatal antiviral immunity. Furthermore, we found that neonatal APCs induce T cell responses in nodular inflammatory foci of the lung, a process which was supposed to be restricted to lymphoid organs. However, the MCMV-specific T cell response was qualitatively different in neonates from that in adults, possibly explaining - in part - the higher susceptibility of newborns. These observations expand our understanding of where adaptive immunity can be initiated, highlights the importance of early local cellular immune responses and sheds more light on neonatal antiviral immunity.

Detection of herpes viruses by multiplex and real-time polymerase chain reaction in bronchoalveolar lavage fluid of patients with acute lung injury or acute respiratory distress syndrome

BACKGROUND

Human herpes viruses (HHVs) are important pathogens in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Rapid and efficient diagnostic tools are needed to detect HHVs in the lung in ALI/ARDS patients.

OBJECTIVES

This study aimed to evaluate the usefulness of multiplex and real-time polymerase chain reaction (PCR) analysis of bronchoalveolar lavage fluid (BALF) for detecting HHV reactivation in ALI/ARDS patients.

METHODS

Between August 2008 and July 2012, eighty-seven BALF samples were obtained from ALI/ARDS patients with unknown etiology and analyzed for HHVs. The types of HHVs in the BALF samples were determined using qualitative multiplex PCR followed by quantitative real-time PCR.

RESULTS

Multiplex PCR identified herpes simplex virus type 1 (HSV-1) (n = 11), Epstein-Barr virus (EBV) (n = 16), cytomegalovirus (CMV) (n = 21), HHV type 6 (HHV-6) (n = 2), and HHV-7 (n = 1) genomic DNA in 35 (40%) of the BALF samples, including 14 (16%) samples containing 2 or 3 HHV types. CMV and EBV reactivation was rare in immunocompetent patients, whereas reactivation of HSV-1 was predominantly observed in intubated patients regardless of their immune status. Overall, HHVs were almost exclusively found in patients with immunosuppression or endotracheal intubation. Real-time PCR detected 0.95-1.59 × 10(6) copies of viral DNA/μg human genome DNA, and HSV-1 (n = 4), CMV (n = 9), and HHV-6 (n = 1) were identified as potentially pathogenic agents.

CONCLUSIONS

The implementation of multiplex and real-time PCR of BALF was feasible in ALI/ARDS patients, which allowed efficient detection and quantification of HHV DNA.

Computed tomography findings in patients with H1N1 influenza A infection

The present study aimed to review high resolution computed tomography findings in patients with H1N1 influenza A infection. The most common tomographic findings include ground-glass opacities, areas of consolidation or a combination of both patterns. Some patients may also present bronchial wall thickening, airspace nodules, crazy-paving pattern, perilobular opacity, air trapping and findings related to organizing pneumonia. These abnormalities are frequently bilateral, with subpleural distribution. Despite their nonspecificity, it is important to recognize the main tomographic findings in patients affected by H1N1 virus in order to include this possibility in the differential diagnosis, characterize complications and contribute in the follow-up, particularly in cases of severe disease.

Imaging pneumonia in immunocompetent and immunocompromised individuals

PURPOSE OF REVIEW

The article aims to indicate the current role of radiological imaging in immune competent and immunocompromised patients with pneumonia. The radiological findings in the most common conditions will be reviewed.

RECENT FINDINGS

Three basic patterns of radiographic abnormality are recognized: lobar (nonsegmental) pneumonia; bronchopneumonia (lobular pneumonia); and interstitial pneumonia. The chest radiograph remains the initial radiological investigation. Computed tomography (CT) is more sensitive than the chest radiograph. The appearances on CT with certain infections such as mycoplasma, invasive aspergillosis, and pneumocystis, in the appropriate clinical setting, may allow a treatment decision to be made when obtaining fluid or tissue for culture is problematical. MRI technology is advancing and this technique may provide an option for follow-up of chronic disease in younger patients in whom radiation exposure is a concern, but MRI does not yet match CT as a diagnostic test in this field.

SUMMARY

Radiology retains a key role in diagnosing pneumonia, excluding pneumonia, following up patients to check for resolution and to evaluate potential complications. The chest radiograph remains the initial examination. CT is more sensitive and with certain infections more specific. MRI provides an option for monitoring progress, although cannot yet match CT as an initial diagnostic test.

Pulmonary Interstitium

The first step in the radiographic evaluation of interstitial lung disease begins with a fundamental knowledge of the anatomy of the pulmonary interstitium and the different patterns of disruption. The anatomy of the pulmonary interstitium as demonstrated on CT of the chest with high resolution cuts is largely essential to establish the various radiological patterns that define interstitial lung disease such as the tree-in-bud, ground-glass opacity, crazy -paving, etc.

Mimics in chest disease: interstitial opacities

Septal, reticular, nodular, reticulonodular, ground-glass, crazy paving, cystic, ground-glass with reticular, cystic with ground-glass, decreased and mosaic attenuation pattern characterise interstitial lung diseases on high-resolution computed tomography (HRCT). Occasionally different entities mimic each other, either because they share identical HRCT findings or because of superimposition of patterns. Idiopathic pulmonary fibrosis (IPF), fibrosis associated with connective tissue disease, asbestosis, end-stage sarcoidosis or chronic hypersensitivity pneumonitis (HP) may present with lower zone, subpleural reticular pattern associated with honeycombing. Lymphangiomyomatosis may be indistinguishable from histiocytosis or extensive emphysema. Both pulmonary oedema and lymphangitic carcinomatosis may be characterised by septal pattern resulting from thickened interlobular septa. Ill-defined centrilobular nodular pattern may be identically present in HP and respiratory bronchiolitis–associated with interstitial lung disease (RBILD). Sarcoidosis may mimic miliary tuberculosis or haematogenous metastases presenting with miliary pattern, while endobronchial spread of tuberculosis may be indistinguishable from panbronchiolitis, both presenting with tree-in-bud pattern. Atypical infection presenting with ground-glass mimics haemorrhage. Ground-glass pattern with minimal reticulation is seen in desquamative interstitial pneumonia (DIP), RBILD and non-specific interstitial pneumonia (NSIP). Obliterative bronchiolitis and panlobular emphysema may present with decreased attenuation pattern, while obliterative bronchiolitis, chronic pulmonary embolism and HP may manifest with mosaic attenuation pattern. Various mimics in interstitial lung diseases exist. Differential diagnosis is narrowed based on integration of predominant HRCT pattern and clinical history.

Teaching Points

• To learn about the different HRCT patterns, which are related to interstitial lung diseases.

• To be familiar with the more “classical” entities presenting with each HRCT pattern.

• To discuss possible overlap of different HRCT patterns and the more common mimics in each case.

• To learn about some clues that help differentiate the various diagnostic mimics on HRCT.

Incidence and management of mTOR inhibitor-associated pneumonitis in patients with metastatic renal cell carcinoma

The administration of mammalian target of rapamycin (mTOR) inhibitors can give rise to a potentially life-threatening adverse event, often referred to as 'non-infectious pneumonitis' (NIP), which is characterized by non-infectious, non-malignant, and non-specific inflammatory infiltrates. Patients usually present with cough and/or dyspnoea. We provide a brief description of the mechanism of action of mTOR inhibitors and their overall safety in patients with metastatic renal cell carcinoma (mRCC) and review the literature on mTOR inhibitor-associated NIP in patients with solid tumours. The review was used to derive questions on the diagnosis, management, and monitoring of mRCC patients with NIP, and to develop a decision tree for use in routine clinical practise. A key recommendation was the subdivision of grade 2 NIP into grades 2a and 2b, where grade 2a is closer to grade 1 and grade 2b to grade 3. This subdivision is important because it takes into account the nature and severity of clinical symptoms potentially related to NIP, either the onset of new symptoms or the worsening of existing symptoms, and thus determines the type and frequency of follow-up. It also helps to identify a subgroup of patients in whom treatment, if effective, may be continued without dose adjustment.

Computed tomography findings of influenza A (H1N1) pneumonia in adults: pattern analysis and prognostic comparisons

AIM

The aim of this study was to evaluate retrospectively the chest computed tomography findings of influenza A (H1N1) pneumonia and their relationship with clinical outcome.

METHODS

Chest computed tomography findings and clinical outcomes of 76 patients with influenza A (H1N1) pneumonia were assessed. Computed tomography findings were evaluated for the presence and distribution of parenchymal abnormalities, which were then classified into 3 patterns: bronchopneumonia, cryptogenic organizing pneumonia (COP), and acute interstitial pneumonia (AIP) patterns. Clinical courses were divided into 2 groups on the basis of necessitating admission to intensive care unit or mechanical ventilation therapy (group 1) or not (group 2).

RESULTS

Lung abnormalities consisted of ground-glass opacity (93%, 71 patients), consolidation (66%, 50 patients), small nodules (61%, 46 patients), and tree-in-bud sign (22%, 17 patients). Lesions were classified into bronchopneumonia (49%, 37 patients), COP (30%, 23 patients), AIP (18%, 14 patients), and unclassifiable (3%, 2 patients) patterns. Patients with AIP pattern had a tendency to belonging to group 1, accounting for 40% (8 of 20 patients) of group 1 course and only 11% (6 of 56 patients) of group 2 course (P = 0.004).

CONCLUSIONS

Computed tomography findings of influenza A (H1N1) pneumonia in adults can be classified into COP, AIP, and bronchopneumonia patterns. Patients presenting with AIP pattern have a tendency to show poor prognosis.