Practical issues concerning imaging of pulmonary infection in children

Pediatric Lower Respiratory Tract Infections: Imaging Guidelines and Recommendations

Lower respiratory tract infection (LRTI) remains a major cause of morbidity and mortality in children. Various organisms cause LRTI, including viruses, bacteria, fungi, and parasites, among others. Infections caused by 2 or more organisms also occur, sometimes enhancing the severity of the infection. Medical imaging helps confirm a diagnosis but also plays a role in the evaluation of acute and chronic sequelae. Medical imaging tests help evaluate underlying pathology in pediatric patients with recurrent or long-standing symptoms as well as the immunocompromised.

Lung magnetic resonance imaging for pneumonia in children

Technical factors have historically limited the role of MRI in the evaluation of pneumonia in children in routine clinical practice. As imaging technology has advanced, recent studies utilizing practical MR imaging protocols have shown MRI to be an accurate potential alternative to CT for the evaluation of pneumonia and its complications. This article provides up-to-date MR imaging techniques that can be implemented in most radiology departments to evaluate pneumonia in children. Imaging findings in pneumonia on MRI are also reviewed. In addition, the current literature describing the diagnostic performance of MRI for pneumonia is discussed. Furthermore, potential risks and limitations of MRI for the evaluation of pneumonia in children are described.

Infections

Lower respiratory tract infection is a very common illness in children and is a significant cause of morbidity and mortality. Clinical signs and symptoms are nonspecific especially in infants and younger children and some even present with nonrespiratory complaints. Infectious agents causing pneumonia is not limited to viruses and bacteria, but it could also be due to Mycoplasma, Mycobacteria, fungi, protozoa, and parasites. Coinfection with two or more microbial agents can also occur. The etiologic agent of lower respiratory infection in a child is often difficult to obtain, but the patient’s age can help narrow the possible cause. Microbiological tests are important but could be difficult to obtain especially in younger children. Various medical imaging modalities not only play an important role as an aid in diagnosis but can also help during and after therapy. Imaging can also help evaluate complications to pneumonia and exclude other causes of respiratory distress including underlying developmental anomalies, foreign body, gastroesophageal reflux disease, and aspiration. In this chapter, the imaging modalities utilized in the detection of pulmonary infections will be discussed. The spectrum of typical imaging findings for various etiologic agents in both immunocompetent and immunocompromised children will be presented.

Nosocomial infection: A risk factor for a complicated course in children with respiratory syncytial virus infection – Results from a prospective multicenter German surveillance study

BACKGROUND

Nosocomially acquired respiratory syncytial virus infections (RSV-NI) may cause serious problems in hospitalized paediatric patients. Hitherto, prospectively collected representative data on RSV-NI from multicenter studies in Germany are limited.

METHODS

The DMS RSV Ped database was designed for the prospective multicenter documentation and analysis of clinically relevant aspects of the management of inpatients with RSV-infection. The study covered six consecutive seasons (1999-2005); the surveillance took place in 14 paediatric hospitals in Germany.

RESULTS

Of the 1568 prospectively documented RSV-infections, 6% (n=90) were NI and 94% (n=1478) were community acquired (CA). A significantly higher proportion in the NI group displayed additional risk factors like prematurity, chronic lung disease, mechanical ventilation (med. history), congenital heart disease, and neuromuscular impairment. Of all NI, 55% occurred in preterms (30.6% of all RSV-infections in preterms with severe chronic lung disease of prematurity were NI). Illness severity as well as the total mortality, but not the attributable mortality was significantly higher in the NI group. In the multivariate analysis, NI was significantly associated with the combined outcome 'complicated course of disease'.

CONCLUSION

This is the first prospective multicenter study from Germany, which confirms the increased risk of a severe clinical course in nosocomially acquired RSV-infection. Of great concern is the high rate of (preventable) NI in preterms, in particular in those with severe chronic lung disease or with mechanical ventilation due to other reasons.

Respiratory syncytial virus infection in 406 hospitalized premature infants: results from a prospective German multicentre database

Premature birth, chronic lung disease of prematurity (CLD), congenital heart disease and immunodeficiency predispose to a higher morbidity and mortality in respiratory syncytial virus (RSV) infection. This study describes the preterms hospitalised with RSV infection from the prospective German DSM RSV Paed database. The DMS RSV Paed database was designed for the prospective multicentre documentation and analysis of clinically relevant aspects of the management of inpatients with RSV infection. This study covers six consecutive RSV seasons (1999-2005); the surveillance took place in 14 paediatric hospitals in Germany. Of the 1,568 prospectively documented RSV infections, 26% (n=406) were observed in preterms [vs. 1,162 children born at term (74%)] and 3% (n=50) had CLD, of which 49 had received treatment in the last 6 months ('CLDplus'). A significantly higher proportion in the preterm group had congenital heart disease, nosocomial infection, and neuromuscular impairment. There were significantly more children older than 24 months in the preterm group. The attributable mortality was 0.2% (n=2) in children born at term vs. 1.2% (n=5) in the preterm group (p=0.015) [preterm plus CLD 8.0% (n=4 of 50); McIntosh grade 1, 8.6% (n=3 of 35) and McIntosh Grade 4, 15% (n=3 of 20)]. Eight patients were categorized as 'palivizumab failures'. In the multivariate analysis, premature birth, CLD(plus), and nosocomial infection were significantly and independently associated with the combined outcome 'complicated course of disease'. In conclusion, this is the first prospective multicentre study from Germany that confirms the increased risk for severe RSV disease in preterms, in particular in those with CLD treated in the last 6 months before the onset of the infection. From the perspective of our results, the statements of the German Society of Paediatric Infectious Diseases considering the use of passive immunisation (2003) seem reasonable.

Prospective study of Human Bocavirus (HBoV) infection in a pediatric university hospital in Germany 2005/2006

Background

Human Bocavirus (HBoV), a new species of the genus parvovirus newly detected in 2005, seems to be a worldwide distributed pathogen among children with respiratory tract infection (prevalence 2%–18%). Recently published retrospective studies and one prospective birth cohort study suggest that HBoV-primary infection occurs in infants.

Methods

Prospective single center study over one winter season (November 2005–May 2006) with hospitalized children without age restriction using PCR-based diagnostic methods.

Results

HBoV DNA was detected in 11 (2.8%) of 389 nasopharyngeal aspirates from symptomatic hospitalized children (median age 9.0 months; range: 3–17 months). RSV, HMPV, HCoV, and Influenza B were detected in 13.9% (n = 54), 5.1% (n = 20), 2.6% (n = 10), and 1.8% (n = 7), respectively. There was no influenza A DNA detected in any of the specimens. The clinical diagnoses were acute wheezing (bronchitis) in four patients, radiologically confirmed pneumonia in six patients (55%) and croup syndrome in one patient. In five to six patients with pneumonia, HBoV was the only pathogen detected. While no patient had to be mechanically ventilated, 73% needed oxygen supplementation. In four (36.4%) patients at least one other viral pathogen was found (plus RSV n = 3; 27.3%; Norovirus n = 1; 9.1%).

Conclusion

HBoV causes severe respiratory tract infections in infants and young children. Its role as a copathogen and many other open questions has to be defined in further prospective studies.

Hospitalized children with respiratory syncytial virus infection and neuromuscular impairment face an increased risk of a complicated course

BACKGROUND

Respiratory syncytial virus (RSV) infection is an important cause of viral respiratory tract infection in children. In contrast to other confirmed risk factors that predispose to a higher morbidity and mortality, the particular risk of a preexisting neuromuscular impairment (NMI) in hospitalized children with RSV infection has not been prospectively studied in a multicenter trial.

METHODS

The DMS RSV Paed database was designed for the prospective multicenter documentation and analysis of all clinically relevant aspects of the management of inpatients with RSV infection. Patients with clinically relevant NMI were identified according to the specific comments of the attending physicians and compared with those without NMI.

RESULTS

This study covers 6 consecutive seasons; the surveillance took place in 14 pediatric hospitals in Germany from 1999 to 2005. In total, 1568 RSV infections were prospectively documented in 1541 pediatric patients. Of these, 73 (4.7%) patients displayed a clinically relevant NMI; 41 (56%) NMI patients had at least 1 additional risk factor for a severe course of the infection (multiple risk factors in some patients; prematurity in 30, congenital heart disease in 19, chronic lung disease 6 and immunodeficiency in 8). Median age at diagnosis was higher in NMI patients (14 vs. 5 months); NMI patients had a greater risk of seizures (15.1% vs. 1.6%), and a higher proportion in the NMI group had to be mechanically ventilated (9.6% vs. 1.9%). Eventually, the attributable mortality was significantly higher in the NMI group (5.5% vs. 0.2%; P < 0.001 for all). Multivariate logistic regression confirmed that NMI was independently associated with pediatric intensive care unit (PICU) admission (OR, 4.94; 95% CI, 2.69-8.94; P < 0.001] and mechanical ventilation (OR, 3.85; 95% CI, 1.28-10.22; P = 0.017).

CONCLUSION

This is the first prospective multicenter study confirming the hypothesis that children with clinically relevant NMI face an increased risk for severe RSV-disease. It seems reasonable to include NMI as a cofactor into the decision algorithm of passive immunization.

Nosocomial respiratory syncytial virus infection: Impact of prospective surveillance and targeted infection control

BACKGROUND

Nosocomially acquired respiratory syncytial virus (RSV) infections cause serious problems in hospitalized patients. An increased effort should be made to describe the problems connected with such infections in pediatric hospitals, with the aim of reducing the occurrence of nosocomial RSV infections (NI).

METHODS

A specialized database was introduced for surveillance and a multifaceted barrier concept based on the CDC recommendations was developed for the control of NI in a university children's hospital in Germany.

RESULTS

Between 1999 and 2002 (November 1-April 30), 283 RSV infections (general population) were prospectively documented. Thirty-nine cases (13.8%) were nosocomial infections (NI) with an incidence density (ID) of 0.99/1000 patient days; 48.7% of all NI were found in prematurely born infants. Following the introduction of a surveillance and prevention policy, a 9-fold decrease of the ID (1.67 vs. 0.18/1000 patient-days) was found when comparing the first and the last season. Intensive care treatment was required in 18% of all documented RSV-infections, in 48.7% of all NI cases and in 43.5% of all RSV-infected prematurely born infants. Overall RSV-related mortality was 0.71%.

CONCLUSIONS

Early diagnosis, a strict cohorting and contact isolation policy, and prospective surveillance contribute to the reduction of nosocomial RSV infection.

Human metapneumovirus infections cause similar symptoms and clinical severity as respiratory syncytial virus infections

Human metapneumovirus (hMPV) is a recently discovered pathogen in respiratory tract infection. The published literature suggests milder illness severity in hMPV compared with respiratory syncytial virus (RSV) infection. In two consecutive seasons, 637 nasopharyngeal aspirates from pediatric patients were tested by hMPV polymerase chain reaction, and risk factors and clinical and laboratory items were analyzed. The hMPV patients were compared with hMPV-negative but RSV-positive patients by matched pair analysis. HMPV was detected in 17.9% of all samples. In total, 88 hMPV-infected patients with complete datasets were considered. More than half of all hMPV patients were older than 12 months, 45.5% had at least one risk factor for a severe course of viral respiratory tract infection, and 27.3% were born prematurely, 15.9% with a birth weight <1,500 g. At least one other virus was also detected in 39 patients (44.3%; RSV in 29.5%). Coinfection did not result in greater severity of illness. On matched pair analysis (hMPV-positive/RSV-negative vs. hMPV-negative/RSV-positive), the epidemiological and clinical features of hMPV infection were similar to those of RSV infection, as in the hMPV group higher proportions of patients with hypoxemia on admission (33% vs. 21%) and of intensive care treatment (20.8% vs. 10.4%) were observed. More hMPV patients showed lobar infiltrates in radiological chest examination. In 60% of all hMPV infections, the attending physicians prescribed antimicrobial chemotherapy. We conclude that in hospitalized children, hMPV infection is as serious as RSV infection and therefore deserves the same attention. Virologic diagnosis from respiratory secretions is mandatory because clinical, laboratory, and radiological signs cannot sufficiently discriminate between viral and bacterial respiratory tract infection in infants and children.

[Emergency pediatric thoracic radiology]

Pediatric thoracic emergencies are frequent and may be due to a large spectrum of lesions including traumatic and non traumatic pathologies, such as foreign bodies, mediastinal tumors, pulmonary infections, asthma, pneumothorax and delayed manifestations of congenital chest malformations. Emergencies require rapid diagnosis to make a treatment plan and in most cases, radiology plays an essential role. Plain chest radiographs remain the initial study with inspiratory films. In certain circumstances, the use of expiratory films is absolutely necessary. Ultrasonogragraphy is the primary modality for evaluation of pleural effusions. Computed tomography (CT), with volume acquisition and more rapid scanning, is a technique capable of imaging the lungs and mediastinum with excellent spatial resolution in the pediatric population. CT provides more information than chest radiographs. This explains the increasing indications of CT in the evaluation of pediatric thoracic emergencies, more particularly traumatic emergencies.

Imaging in immunocompetent children who have pneumonia

This article discusses the common clinical scenarios regarding otherwise healthy children who develop suspected pneumonia in which imaging becomes an issue. The following topics are covered concerning the roles of imaging in the management of pneumonia: evaluation for possible pneumonia, determination of a specific etiologic agent, exclusion of other pathology, evaluation of the child with failure of pneumonia to clear, and evaluation of complications related to pneumonia.

Community-acquired pneumonia

Community-acquired pneumonia (CAP) remains an important cause of morbidity and mortality. Streptococcus pneumoniae is the most common pathogen and respiratory syncitial virus the most important viral pathogen in children. The role of urinary antigen testing and PCR for the diagnosis forS. pneumoniae infection has been an important adjunct to clinical examination, showing good sensitivity and specificity. Host-related immune responses play an important role in defining the severity of illness. Other than the use of Activated Protein C and immunization, the clinical use of therapies designed to modulate these abnormal responses remains largely experimental. The 7-valent vaccine represents a major advance in the prevention of invasive pneumococcal disease. The importance of effective triage and the deleterious effects of deviation from protocols are underscored. Continuous positive pressure ventilation and noninvasive mechanical ventilation are available as options for respiratory support in cases of severe CAP and require further evaluation.

Lower respiratory infections in children

Lower respiratory infections (LRIs) continue to threaten the health of children worldwide and are exacerbated by global environmental problems such as air pollution [1]. In the developing world where nutrition remains poor and access to healthcare is scarce, LRIs are the most common cause of illness and death in children. Outcomes of LRI illness are far better in developed countries, but the overall morbidity of LRI is still high and may exceed that of other age groups [2]. The environmental "health" of our planet remains an issue closely linked to the health of children--particularly in terms of LRI disease. It is also clear that further progress in preventing, diagnosing, and treating LRI disease will have a significant impact on the health of children. The recent literature details both progress and clinical dilemmas of LRI-related illnesses in children. Lower respiratory infection disease is considered to include the following entities: acute lower respiratory infections, pneumonia, atypical pneumonia, bronchitis, and bronchiolitis. This update will review current reports on the evaluation of children with LRIs, bacterial and viral LRIs, and sequelae of LRIs.