Progressive damage on high resolution computed tomography despite stable lung function in cystic fibrosis

Chest computed tomography scans should be considered as a routine investigation in cystic fibrosis

Cystic fibrosis (CF) patients demonstrate lung inflammation and infection beginning early in life. Both inflammation and infection lead to irreversible structural lung damage, primarily as bronchiectasis and fibrosis. The course of CF varies widely between patients due to genotypic and environmental differences. The primary aim of CF therapy is to prevent or delay structural damage and conserve lung function. Adequate monitoring of CF lung disease is paramount to tailoring treatment to a patient's need. Pulmonary function tests (PFTs) are important in monitoring lung function. PFTs, however, are only an indirect measure of lung structure and are insensitive to localised or early damage. By contrast, computed tomography (CT) is currently the most sensitive tool to monitor lung structure. As up to 50% of patients will have discordant staging of lung disease when PFTs are compared to CT findings, both methods are needed to adequately assess a patient's pulmonary condition and tailor the treatment strategy to the patient's needs.

High-resolution computed tomography (HRCT) should not be considered as a routine assessment method in cystic fibrosis lung disease

High-resolution computed tomography (HRCT) scanning of the chest should not be considered a routine clinical investigation in the management of CF. Although it demonstrates the detection of early lung damage in children with cystic fibrosis (CF), before HRCT can be considered for routine clinical use in CF it needs to be shown that the benefit from the information obtained will out-weigh potential risks. There is insufficient evidence for the benefit of HRCT for its inclusion into routine care. Moreover, in the absence of information resulting in change in management, HRCT has the potential to increase anxiety for both clinicians and families. In order to advocate for incorporating this technology into routine CF care, further support for its role in management decisions is needed.

Assessment of lung disease in children with cystic fibrosis using hyperpolarized 3-Helium MRI: comparison with Shwachman score, Chrispin-Norman score and spirometry

This study assesses the feasibility of hyperpolarized 3-Helium MRI in children with cystic fibrosis (CF) and correlates the findings with standard clinical parameters based on chest radiograph (CXR) and pulmonary function tests (PFT). An uncontrolled, observational study in eighteen children with cystic fibrosis aged 5 - 17 years (median 12.1 years), with different severity of disease was carried out. All subjects underwent routine clinical assessment including PFT and standard auxology; CXR was obtained and Shwachman and Chrispin-Norman scores calculated. Hyperpolarized 3-He magnetic resonance imaging (MRI) was carried out using a spin-exchange polarizer and a whole body 1.5 T scanner. Ventilation distribution images were obtained during a 21-second breath-hold and scored according to previously defined criteria. Spearman's non-parametric correlations test was performed to assess for statistical significance at the p<0.05 level. The children tolerated the procedure well. No desaturation events were observed during 3-He MRI. A significant, albeit moderate, correlation was found between MRI score and FEV1% predicted (r=-0.41; p=0.047) and FVC% predicted (r=-0.42; p=0.04), while there were trends of correlations between Shwachman score and MRI score (r=-0.38; p=0.06) and Shwachman score and FEV1% predicted (r=0.39; p=0.055). The feasibility of hyperpolarized 3-He MRI in children with CF was demonstrated. MRI appears to be able to demonstrate functional lung changes, although correlations with routine clinical tests are only moderate to poor. This non-ionising radiation technique could be useful for monitoring lung disease and assessing therapy in this patient population.

Thin-Section CT in Patients with Cystic Fibrosis: Correlation with Peak Exercise Capacity and Body Mass Index

PURPOSE

To evaluate whether thin-section chest computed tomographic (CT) findings correlate with exercise capacity, body mass index (BMI), dyspnea, and leg discomfort in patients with cystic fibrosis (CF).

MATERIALS AND METHODS

Institutional ethics committee approval was obtained, and patients provided written informed consent. Twenty-two patients (13 male and nine female patients; mean age, 22 years +/- 5.9; age range, 17-41 years) with stable CF underwent thin-section CT and exercise testing on a cycle ergometer. Three radiologists blinded to the clinical severity of disease and the spirometric findings of all patients independently and randomly scored all scans with a modified Bhalla scoring system. The primary measurement of the outcome of exercise testing was percentage of predicted peak O2 uptake. Univariate (Spearman rank correlation) and multivariate analyses were used to compare thin-section CT, clinical (age, sex, spirometric data, and BMI), and exercise measurements.

RESULTS

The correlation between total thin-section CT score and percentage of predicted peak O2 uptake was stronger than the correlation between the percentage of predicted peak O2 uptake and any clinical measurement (R = -0.60, P < .01). The thin-section CT structural abnormalities that had the strongest correlation with percentage of predicted peak O2 uptake were severity of bronchiectasis and presence of sacculations or abscesses (R = -0.70 and -0.71, respectively; P < .01). Multivariate analysis showed total thin-section CT score to be the only significant predictor of exercise capacity, accounting for 42% of the variance in percentage of predicted peak O2 uptake.

CONCLUSION

In patients with CF, the correlation between thin-section CT score and exercise limitation is stronger than that between spirometry results or BMI and exercise limitation.

Achromobacter xylosoxidans in cystic fibrosis: prevalence and clinical relevance

BACKGROUND

Achromobacter xylosoxidans is increasingly cultured in sputum from cystic fibrosis (CF) patients; nevertheless, there are few published data on the clinical impact of this infection or chronic colonisation.

METHODS

Relying on DNA fingerprinting techniques we studied the prevalence of A. xylosoxidans in our CF population. In a retrospective case control study the clinical status of patients with at least 3 sputum cultures positive for A. xylosoxidans over at least 9 months, at the moment of the first positive culture and during the period of colonisation were compared to age (+/-1 year), gender and to Pseudomonas aeruginosa colonisation controlled CF patients who had never A. xylosoxidans positive sputum cultures.

RESULTS

The prevalence of patients with at least one positive A. xylosoxidans culture was 17.9%. 5.3% of the patients fulfilled the criteria of our definition of colonisation. Colonised patients had a median age of 20 years (range 11-27 years) and a mean colonisation period of 1.5 (+/-0.9) years. At the moment of the first positive culture we found significantly lower Bhalla scores on HRCT scans of the lungs (11+/-3 versus 16+/-3, p<0.002), lower Brasfield chest X-ray scores (14+/-3 versus 18+/-3, p<0.019), lower FVC values (70%+/-22 versus 94%+/-12, p<0.017) and lower FEV(1) values (55%+/-32 versus 78%+/-23, p=0.123), although the latter did not reach significance. There was no significant difference in body mass index (BMI) (18.7+/-3 kg/m2 versus 19.6+/-3 kg/m2, p=0.8). Over the study period A. xylosoxidans-colonised patients did have more need for intravenous antibiotic treatment courses (19 versus 5, p<0.001); nevertheless, there was no significant difference in lung function decline over the study period (FVC: -6.25+/-12.34% versus -5.62+/-8.30%, p 0.77, FEV1: -5.62+/-8.30% versus -1.87+/-11.58%, p<0.47).

CONCLUSIONS

The prevalence of A. xylosoxidans infection or colonisation is probably underestimated. Colonised patients are mostly older, with more pronounced lung damage and lower lung function values. Although there was more need for intravenous antibiotic treatment courses, no faster decline in lung function was observed in A. xylosoxidans positive patients.

Respiratory factors do not limit maximal symptom-limited exercise in patients with mild cystic fibrosis lung disease

To evaluate whether respiratory factors limit exercise capacity in patients with mild cystic fibrosis (CF) lung disease (mean FEV(1) = 76 +/- 7.7% predicted) we stressed the respiratory system of seven patients using added dead space (V(D)). Primary outcomes were exercise duration (Ex(dur)) and maximal oxygen uptake (VO(2max)). Dyspnoea/leg-discomfort were assessed at end-exercise. Ex(dur) was identical between control and V(D) studies (520 +/- 152 versus 511 +/ -166 s, p = NS) as was VO(2max)(1.6 +/- 0.5 versus 1.6 +/- 0.6 L/min, p = NS). Significant resting, sub-maximal and maximal workload increases in minute ventilation (V(E)) were detected (70.8 +/- 13.7 versus 79.5 +/- 16.9 L/min, p < 0.05). Analysis of breathing pattern revealed increases in V(E) were attributable to increases in tidal volume (2.0 +/- 0.5 versus 2.2 +/- 0.6 L, p < 0.05) with no change in respiratory frequency. There was no difference in dyspnoea/leg discomfort between tests. The increase in V(E) in response to V(D), with no change in [Exdur/VO(2max) suggests maximal symptom-limited exercise limitation is not primarily limited by respiratory factors in mild CF lung disease. Focused investigation and treatment of non-respiratory factors contributing to exercise limitation may improve exercise rehabilitation in this patient group.

Is limited computed tomography the future for imaging the lungs of children with cystic fibrosis?

Perspective on the paper by Jiménez et al (see page 388)

Reproducibility of a Scoring System for Computed Tomography Scanning in Cystic Fibrosis

INTRODUCTION

Computerized tomography (CT) scanning shows promise as an outcome surrogate for cystic fibrosis (CF) lung disease progression. The scoring system used to convert the CT image to numeric data is an essential determinant of the performance of CT scanning.

METHODS

Three radiologists independently scored 16 high-resolution CT scans performed on children in the Wisconsin CF Neonatal Screening Project. The test scans were selected to provide a broad range of disease severity. The scoring system provided subscores for the presence and severity of 5 findings of CF lung disease. The sum of the subscores provided a total score. The CT scans were then read again by each of the radiologists at least 11 months later. Using Mixed Effects Linear Model Analysis, the sources of error (scan-to-scan variation, interrater variance, and intrarater variance) were calculated.

RESULTS

For the total score, the scan-to-scan variation was 14.48, interrater variance was 0.28, and intrarater variance was 0.45, with an overall reproducibility of 95%. The square root of scan-to-scan variance, a measure of sensitivity, was 3.81. Evaluation of the subscores showed higher reproducibility for bronchiectasis and hyperinflation (95% and 88%, respectively). The bronchiectasis score was more sensitive than the air-trapping score (1.46 vs. 0.89).

DISCUSSION

This system was developed to provide a reproducible method that could be used to evaluate the lobar location, severity, and extent of a broad spectrum of CT features of CF lung disease, especially in children. This study demonstrates that the overall score is both sensitive to variation in the severity of lung disease and reproducible.

Progression of lung disease on computed tomography and pulmonary function tests in children and adults with cystic fibrosis

BACKGROUND

A study was undertaken to compare the ability of computed tomographic (CT) scores and pulmonary function tests to detect changes in lung disease in children and adults with cystic fibrosis (CF).

METHODS

CT scans and pulmonary function tests were retrospectively studied in a cohort of patients with CF aged 5-52 years for whom two or three CT scans at 3 year intervals were available, together with pulmonary function test results. All CT scans were scored by two observers. Pulmonary function results were expressed as percentage predicted and Z scores.

RESULTS

Of 119 patients studied, two CT scans were available in 92 patients and three in 24. CT (composite and component) scores and lung function both deteriorated significantly (p<0.02). Peripheral bronchiectasis worsened by 1.7% per year in children (p<0.0001) and by 1.5% per year in adults (p<0.0001). Bronchiectasis worsened in 68 of 92 patients while forced expiratory volume in 1 second (FEV1) worsened in 54 of 92 patients; bronchiectasis also deteriorated in 27 patients with stable or improving FEV1. The CT score (and its components) and pulmonary function tests showed similar rates of deterioration in adults and children (p>0.09).

CONCLUSION

The peripheral bronchiectasis CT score deteriorates faster and more frequently than lung function parameters in children and adults with CF, which indicates that pulmonary function tests and CT scans measure different aspects of CF lung disease. Our data support previous findings that the peripheral bronchiectasis CT score has an added value to pulmonary function tests in monitoring CF lung disease.

Dose reduction for CT in children with cystic fibrosis: is it feasible to reduce the number of images per scan?

BACKGROUND

Reducing the dose for each CT scan is important for children with cystic fibrosis (CF).

OBJECTIVE

To determine whether the number of CT images and therefore the dose per CT scan could be reduced without any significant loss of information in children with CF.

MATERIALS AND METHODS

A cohort of children with CF was followed with biennial surveillance CT scans, obtained in inspiration after a voluntary breath-hold as 1-mm thick images at 10-mm intervals from lung apex to base. A random set of 20 baseline CT scans and 10 follow-up CT scans were blinded. Sets of every image (10-mm intervals), every second image (20-mm intervals), every third image (30-mm intervals) and a selection of three and five images were scored randomly using a published CT scoring system by one experienced observer.

RESULTS

The 20 subjects were 10 years of age with a range of 3.7-17.6 years at baseline. Fewer CT images resulted in a significantly lower (less abnormal) CT score and the number of patients positive for abnormalities decreased subsequently. At intervals greater than 20 mm no significant change in CT score over 2 years could be detected, while the CT scores at 10-mm (P=0.02) and 20-mm (P=0.02) intervals worsened significantly.

CONCLUSIONS

A reduction in the number of inspiratory CT images by increasing the interval between images to greater than 10 mm is not a valid option for radiation dose reduction in children with CF.

Cystic fibrosis in neonates and infants

Cystic fibrosis (CF) is a common autosomal recessive disorder, characterized by chronic bronchopulmonary infection, pancreatic insufficiency, and subsequently, other multisystem complications. Most children are diagnosed before school age. Here we review the pathophysiology of the condition, the age-related presentations of CF up until school age, and the appropriate use of diagnostic tests. A specialist centre should supervise treatment. There are exciting new advances in monitoring techniques in the preschool years, including CT scanning, bronchoscopy and gas mixing indices. Recent advances in the knowledge of the molecular biology of CF hold out the hope of specific therapies which can reverse the underlying defect causing death from CF lung disease.

Computed Tomography in the Evaluation of Cystic Fibrosis Lung Disease

The first report of computed tomography (CT) scanning to monitor cystic fibrosis (CF)-related lung disease was published in 1986. Further publications followed, but in general there was little interest in this technique until recently. Two factors in particular have led to this increased interest. First is an increasing realization that pulmonary function tests, long the mainstay of CF evaluation, often underestimate the presence and severity of mild and moderate lung disease. Second is the need for more sensitive outcome measures to assess new therapies. This had led to new interest and a series of important publications. The goal of this article is to present the current status of CT scanning in CF.

Sequential analysis of surfactant, lung function and inflammation in cystic fibrosis patients

BACKGROUND

In a cross-sectional analysis of cystic fibrosis (CF) patients with mild lung disease, reduced surfactant activity was correlated to increased neutrophilic airway inflammation, but not to lung function. So far, longitudinal measurements of surfactant function in CF patients are lacking and it remains unclear how these alterations relate to the progression of airway inflammation as well as decline in pulmonary function over time.

METHODS

As part of the BEAT trial, a longitudinal study to assess the course of airway inflammation in CF, we studied lung function, surfactant function and endobronchial inflammation using bronchoalveolar lavage fluid from 20 CF patients with normal pulmonary function (median FEV1 94% of predicted) at three times over a three year period.

RESULTS

There was a progressive loss of surfactant function, assessed as minimal surface tension. The decline in surfactant function was negatively correlated to an increase in neutrophilic inflammation and a decrease in lung function, assessed by FEV1, MEF(75/25%VC), and MEF(25%VC). The concentrations of the surfactant specific proteins A, C and D did not change, whereas SP-B increased during this time period.

CONCLUSION

Our findings suggest a link between loss of surfactant function driven by progressive airway inflammation and loss of small airway function in CF patients with limited lung disease.

Early detection of lung disease in preschool children with cystic fibrosis

PURPOSE OF REVIEW

Babies with cystic fibrosis are born with essentially normal lungs but rapidly develop inflammation and infection. Evaluation is generally based on history and physical examination until school age, when children become able to perform spirometry. In these 'silent years', however, unrecognized lung damage can occur. Recently, techniques to improve the evaluation of preschool children have been developed, and an assessment of where they fit into clinical and research practice is now needed. This is particularly urgent to select groups of children for new, phenotype-specific therapies, and monitor their effects.

RECENT FINDINGS

The techniques in which there have been major recent advances include physiologic methods, particularly indices of gas mixing; imaging techniques, especially high-resolution computed tomographic scanning; and bronchoscopic studies. The clinical roles of these techniques need to be explored, as do comparisons between techniques.

SUMMARY

The preschool years need no longer be silent. Some simple techniques such as spirometry can be performed in much younger children than conventionally believed to be practical. Others currently require sophisticated apparatus (lung clearance index) or carry potential risks (radiation, high-resolution computed tomographic scanning). We need good long-term, prospective comparisons of these techniques, with measurement of inflammatory markers. We also need to know which are sufficiently reproducible, and indicative of prognosis, for use as endpoints in clinical trials.

Comparison of quiet breathing and controlled ventilation in the high-resolution CT assessment of airway disease in infants with cystic fibrosis

BACKGROUND

Respiratory motion and low lung volumes limit the quality of HRCT examinations in infants and young children.

OBJECTIVE

To assess the effects of respiratory motion and lung inflation on the ability to diagnose airway abnormalities and air trapping (AT) using HRCT in infants with cystic fibrosis (CF).

MATERIALS AND METHODS

HRCT images of the lungs were obtained at four anatomical levels in 16 sedated children (age 2.4+/-1.1 years, mean+/-SD) with CF using controlled ventilation at full lung inflation (CVCT-I), at resting end exhalation (CVCT-E), and during quiet breathing (CT-B). Two blinded reviewers independently and then by consensus scored all images for the presence or absence of bronchiectasis (BE), bronchial wall thickening (BWT), and AT.

RESULTS

Of the 64 images evaluated, BE was identified in 19 (30%) of the CVCT-I images compared to 6 (9%) of the CVCT-E images (P=0.006) and 4 (6%) of the CT-B images (P=0.044). AT was seen in 29 (45%) of the CVCT-E images compared to 14 (22%) of the CVCT-I images (P=0.012) and 12 (19%) of the CT-B images (P=0.012). There were no significant differences in the detection of BWT among the three methods.

SUMMARY

In infants with CF, fully inflating the lung improved the ability to diagnose early BE, and obtaining motion-free images at end exhalation enhanced the detection of AT.

Estimation of cancer mortality associated with repetitive computed tomography scanning

RATIONALE

Low-dose radiation from computed tomography (CT) may increase the risk of certain cancers, especially in children.

OBJECTIVE

We sought to estimate the excess all-cause and cancer-specific mortality, which may be associated with repeated CT scanning of patients with cystic fibrosis (CF).

METHODS

The radiation dose was calculated for a published CF surveillance CT scanning protocol of biennial CT scans, and the risk per scan was estimated using atom-bomb survivor data. A computational model was developed to calculate the excess mortality in a CF cohort associated with radiation from the CT scan and to evaluate the effects of background survival, scanning interval, and level of CT radiation used. The model assumed that there would be no survival benefits associated with repeated surveillance CT scanning.

RESULTS

The average radiation dose for the published CT protocol was 1 mSv. Survival reduction associated with annual scans from age 2 yr until death was approximately 1 mo and 2 yr for CF cohorts, with a median survival of 26 and 50 yr, respectively. Corresponding cumulative cancer mortality was approximately 2 and 13% at age 40 and 65 yr, respectively. Biennial CT scanning reduced all-cause and cumulative cancer mortality by half.

CONCLUSION

Routine lifelong annual CT scans carry a low risk of radiation-induced mortality in CF. However, as the overall survival increases for patients with CF, the risk of radiation-induced mortality may modestly increase. These data indicate that radiation dose must be considered in routine CT imaging strategies for patients with CF, to ensure that benefits outweigh the risks.

[Cystic fibrosis in adults: inter- and intraobserver agreement for the Brasfield and Chrispin-Norman chest radiography scoring systems and correlation with clinical data and spirometry]

OBJECTIVE

Most chest radiography scoring systems for patients with cystic fibrosis have been developed for children but are also used for adults. Our aim was to evaluate the intra- and interobserver variability of 2 radiographic scoring systems in adults with cystic fibrosis and to assess the correlation of these systems with clinical and spirometric parameters.

PATIENTS AND METHODS

The chest x-rays of 24 adult patients with cystic fibrosis were compared using 2 scoring systems (Brasfield and Chrispin-Norman). The x-rays were scored by 2 radiologists and reevaluated 4 months later by 1 of the 2 observers. Intra- and interobserver agreement was assessed using the intraclass and Pearson's correlation coefficients. The radiographic scores were compared to lung function tests and other clinical data.

RESULTS

Both intra- and interobserver agreement were high (r > or = 0.9 and the intraclass correlation coefficient > or = 0.85 with both systems for both samples). Both scoring systems correlated with spirometry results: forced expiratory volume in the first second (FEV1) (r = 0.64 and r = 0.55), FEV1% (r = 0.75 and r = 0.72), and the percentage of forced vital capacity in relation to the predicted value (r = 0.63 and r = 0.056). We found no association between scoring system and sex, age, or body mass index.

CONCLUSIONS

Assessment of chest radiographs of adult patients with cystic fibrosis by the Brasfield and Chrispin-Norman scoring systems shows good intra- and interobserver agreement. Both systems correlate well with lung function variables, especially FEV1.

Dornase Alfa Reduces Air Trapping in Children With Mild Cystic Fibrosis Lung Disease

PURPOSES

To evaluate quantitative air trapping measurements in children with mild cystic fibrosis (CF) lung disease during a 1-year, double-blind, placebo-controlled, recombinant human deoxyribonuclease (rhDNase) [dornase alfa] intervention trial and compare results from quantitative air trapping with those from spirometry or visually scored high-resolution CT (HRCT) scans of the chest.

MATERIALS AND METHODS

Twenty-five children with CF randomized to either daily rhDNase or placebo aerosol were evaluated at baseline, and at 3 months and 12 months by spirometer-triggered HRCT and spirometry. Outcome variables were percentage of predicted FVC, FEV1, and forced expiratory flow, midexpiratory phase (FEF(25-75%)); total and subcomponent visual HRCT scores; and quantitative air trapping measurements derived from chest HRCT images.

RESULTS

At baseline, there were no statistical differences between groups in any of the variables used as an outcome. After 3 months of treatment, both groups had improvements in percentage of predicted FEV1 and FEF(25-75%), and total HRCT visual scores. In contrast, the rhDNase group had a 13% decrease in quantitative air trapping from baseline (severe air trapping [A3]), compared to an increase of 48% in the placebo group (p = 0.023). After 12 months, both groups had declines in percentage of predicted FVC and FEV1, but the rhDNase group retained improvements in percentage of predicted FEF(25-75%) and quantitative air trapping. The mucus plugging and total HRCT visual scores were also improved in the rhDNase group after 12 months of treatment, with and without significant differences between groups (p = 0.026 and p = 0.676). Quantitative air trapping (A3) remained improved in the rhDNase group (- 15.4%) and worsened in the placebo group (+61.3%) with nearly significant differences noted between groups (p = 0.053) after 12 months of treatment.

CONCLUSIONS

Quantitative air trapping is a more consistent sensitive outcome measure than either spirometry or total HRCT scores, and can discriminate differences in treatment effects in children with minimal CF lung disease.

Computed tomography correlates with pulmonary exacerbations in children with cystic fibrosis

RATIONALE

High-resolution computed tomography (HRCT) has been suggested as a potential outcome surrogate for cystic fibrosis (CF) lung disease. An important attribute of a valid outcome surrogate is that the surrogate reflects true clinical outcomes.

OBJECTIVES

We performed this study to validate HRCT, a proposed surrogate outcome measure for CF lung disease, against a true clinical outcome, the number of respiratory tract exacerbations occurring in 2 yr, and to assess the correlation of CT scores and pulmonary function tests (PFTs) with this clinical outcome.

METHODS

CTs and PFTs were performed on 6- to 10-yr-old children at the beginning and end of a 2-yr study during which the number of exacerbations were recorded. Spearman correlations and Poisson models were used to assess the correlation of the number of exacerbations with baseline values and changes in PFTs and CT scores.

MEASUREMENTS AND MAIN RESULTS

Nine of 61 subjects had a total of 22 respiratory tract exacerbations. At baseline, PFTs and four CT scores showed significant correlation with number of exacerbations, but no variable by itself predicted exacerbations with high accuracy. For change over the 2-yr period, three CT scores showed significant correlation with exacerbations, whereas no PFTs showed significant correlation.

CONCLUSION

This is the first study showing correlation between CT and a true clinical outcome. Change in CT scores correlates moderately well with the number of exacerbation. Poor correlation between change in FEV1 and exacerbations suggests that HRCT may be a more appropriate outcome surrogate for longitudinal studies of young children.

Cystic fibrosis lung disease: genetic influences, microbial interactions, and radiological assessment

Cystic fibrosis (CF) is a multiorgan disease caused by mutation of the CF transmembrane conductance regulator (CFTR) gene. Obstructive lung disease is the predominant cause of morbidity and mortality; thus, most efforts to improve outcomes are directed toward slowing or halting lung-disease progression. Current therapies, such as mucolytics, airway clearance techniques, bronchodilators, and antibiotics, aim to suppress airway inflammation and the processes that stimulate it, namely, retention and infection of mucus plaques at the airway surface. New approaches to therapy that aim to ameliorate specific CFTR mutations or mutational classes by restoring normal expression or function are being investigated. Because of its sensitivity in detecting changes associated with early airway obstruction and regional lung disease, high-resolution CT (HRCT) complements pulmonary function testing in defining disease natural history and measuring response to both conventional and experimental therapies. In this review, perspectives on the genetics and microbiology of CF provide a context for understanding the increasing importance of HRCT and other imaging techniques in assessing CF therapies.

Asthma research: the real action is in children

Many adult diseases have their roots in infancy or even prenatally. If events that initiate these diseases, as opposed to those that propagate the disease state, are to be understood, then the difficult area of how ethically to research problems in infancy must be tackled. Furthermore, the predisposition to archetypally 'pure' adult problems such as chronic obstructive pulmonary disease, may lie antenatally, the effects being masked until the lung starts to age. An additional factor is that the success of paediatricians, for example in ensuring the survival of extremely premature, low birth weight infants leads to adult survivors with potentially a whole new morbidity. The first prerequisite to making progress is a sound understanding of the development of the normal lung and how adverse environmental and genetic influences, such as exposure to environmental tobacco smoke and maternal atopy, respectively, may affect growth. This paper focuses on three key areas: the implications of different pre-school wheezing phenotypes for adult disease; the importance of very early life events in cystic fibrosis; and the long term consequences of chronic lung disease of prematurity. Finally, the ethical principles that must underpin future research in pre-school children is discussed, as well as the means we might use to further our understanding of the relevant early disease processes.

Changes in airway dimensions on computed tomography scans of children with cystic fibrosis

RATIONALE

In cystic fibrosis (CF), chronic bacterial infection and inflammation lead to progressive airway wall thickening and lumen dilatation.

OBJECTIVES

To quantify airway wall thickening and lumen dilatation in children with CF over a 2-year interval.

METHODS

Children with CF (n = 23) who had two computed tomography (CT) scans (CT(cf1) and CT(cf2)) combined with pulmonary function tests (PFTs), with a 2-year interval between measurements, were compared with control subjects (n = 21) who had one CT (CT(controls)). On cross-sectional cut airway-artery pairs, airway wall area (WA), airway lumen area (LA) and perimeter, and arterial area (AA) were quantified. LA/AA (= marker of bronchiectasis), airway wall thickness (AWT), and WA/AA (= markers of wall thickness) were calculated. CT scans were scored using four different scoring systems. PFTs were expressed as percent predicted.

RESULTS

Airway WA-to-AA ratio was 1.45 (p < 0.001) and airway LA-to-AA ratio was 1.92 times higher (p < 0.001) in children with CF compared with age-matched control subjects. LA/AA and WA/AA remained unchanged from CT(cf1) to CT(cf2) and did not increase with age. AWT as a function of airway size increased from CT(cf1) to CT(cf2) by 2% (0.03 mm; p = 0.02). The change in AWT was inversely related to the change in forced expiratory flow between 25 and 75% of expiratory VC (p = 0.002).

CONCLUSIONS

In CF, quantitative measurements of airways on CT scans show an increased ratio between airway LA and AA and progressive airway wall thickening. Scoring systems show progression of bronchiectasis but unchanged AWT. PFTs remained stable.

High-resolution CT scanning: potential outcome measure

PURPOSE OF REVIEW

High-resolution CT (HRCT) imaging of the chest can provide both structural and functional lung analysis useful to evaluate initial and progressive cystic fibrosis (CF) lung disease. Chest HRCT scoring systems have been used to evaluate the extent and severity of CF specific airway and lung parenchymal disease. The purpose of this review is to summarize recent developments in HRCT and volumetric chest CT imaging, CF chest CT scoring systems, and review how HRCT/volumetric CT can provide useful outcome measures for future CF clinical research.

RECENT FINDINGS

Early manifestation of CF lung disease determined by chest CT/HRCT imaging in CF infants and children with mild disease include regional air trapping and bronchial wall thickness. The distribution of findings in more progressed CF lung disease are heterogeneous, and there appears to be a large amount of nonhomogeneity of progressive lung pathology. Recent CF studies have used new clinical CT parameters such as quantitative air trapping, quantitative airway measurements, and a composite CT/pulmonary function test (PFT) score, which appear to be promising new outcome measures that are more sensitive than global pulmonary function measurements or total chest CT scores in discriminating early or mild CF lung disease and treatment effects during clinical interventions.

SUMMARY

Chest HRCT and volumetric CT imaging can detect regional CF lung changes before changes in global pulmonary function measurements. Chest HRCT scoring has been used in descriptive studies defining CF lung disease severity, in longitudinal studies to define progression of disease, and in clinical intervention studies to evaluate treatment effects. In the last 2 years, CF CT research has evolved from solely using chest HRCT scoring systems to utilization of composite CT/PFT scores, quantitative airway and air trapping measurements, and the utilization of volumetric CT imaging to evaluate three-dimensional data sets in patients with CF lung disease.

Pulmonary Surfactant, Lung Function, and Endobronchial Inflammation in Cystic Fibrosis

Cystic fibrosis (CF) lung disease is primarily a disease of the small airways. We hypothesized that even in patients with normal lung function, a reduced surfactant function would be present and favor small airway obstruction. Bronchoalveolar lavages from 76 patients with CF (5-31 years, median 11) with well-conserved lung function (FEV1 94% predicted, range 78-121) and from 10 healthy control subjects were investigated. The deviation of the biophysical surfactant performance from normal, assessed in a bubble surfactometer, was small; however, the ability of the surfactant to maintain the patency of a narrow airway (% open) was significantly reduced. Surfactant protein (SP)-C level was increased, SP-B and SP-D were unchanged, whereas SP-A was decreased. Among the patients with CF, neutrophilic inflammation was modestly related to a poorer surfactant activity, but not to lung function. SP-D was reduced in proportion to the degree of inflammation and in the presence of bacteria. These findings in a large cohort of patients with CF with normal lung function show that the endobronchial airway inflammation is linked to early perturbations of the biophysical properties and immunologic components of pulmonary surfactant and opens fields for novel therapeutic interventions.