Multidetector high-resolution computed tomography of the lungs: protocols and applications

Impact of ultra-high-resolution imaging of the lungs on perceived diagnostic image quality using photon-counting CT

OBJECTIVES

To compare clinical image quality and perceived impact on diagnostic interpretation of chest CT findings between ultra-high-resolution photon-counting CT (UHR-PCCT) and conventional high-resolution energy-integrating-detector CT (HR-EIDCT) using visual grading analysis (VGA) scores.

MATERIALS AND METHODS

Fifty patients who underwent a UHR-PCCT (matrix 512 × 512, 768 × 768, or 1024 × 1024; FOV average 275 × 376 mm, 120 × 0.2 mm; focal spot size 0.6 × 0.7 mm) between November 2021 and February 2022 and with a previous HR-EIDCT within the last 14 months were included. Four readers evaluated central and peripheral airways, lung vasculature, nodules, ground glass opacities, inter- and intralobular lines, emphysema, fissures, bullae/cysts, and air trapping on PCCT (0.4 mm) and conventional EIDCT (1 mm) via side-by-side reference scoring using a 5-point diagnostic quality score. The median VGA scores were compared and tested using one-sample Wilcoxon signed rank tests with hypothesized median values of 0 (same visibility) and 2 (better visibility on PCCT with impact on diagnostic interpretation) at a 2.5% significance level.

RESULTS

Almost all lung structures had significantly better visibility on PCCT compared to EIDCT (p < 0.025; exception for ground glass nodules (N = 2/50 patients, p = 0.157)), with the highest scores seen for peripheral airways, micronodules, inter- and intralobular lines, and centrilobular emphysema (mean VGA > 1). Although better visibility, a perceived difference in diagnostic interpretation could not be demonstrated, since the median VGA was significantly different from 2.

CONCLUSION

UHR-PCCT showed superior visibility compared to HR-EIDCT for central and peripheral airways, lung vasculature, fissures, ground glass opacities, macro- and micronodules, inter- and intralobular lines, paraseptal and centrilobular emphysema, bullae/cysts, and air trapping.

CLINICAL RELEVANCE STATEMENT

UHR-PCCT has emerged as a promising technique for thoracic imaging, offering improved spatial resolution and lower radiation dose. Implementing PCCT into daily practice may allow better visibility of multiple lung structures and optimization of scan protocols for specific pathology.

KEY POINTS

• The aim of this study was to verify if the higher spatial resolution of UHR-PCCT would improve the visibility and detection of certain lung structures and abnormalities. • UHR-PCCT was judged to have superior clinical image quality compared to conventional HR-EIDCT in the evaluation of the lungs. UHR-PCCT showed better visibility for almost all tested lung structures (except for ground glass nodules). • Despite superior image quality, the readers perceived no significant impact on the diagnostic interpretation of the studied lung structures and abnormalities.

Photon Counting CT: Technical Principles, Clinical Applications, and Future Prospects

Photon-counting computed tomography (PCCT) is a new technique that utilizes photon-counting detectors to convert individual X-ray photons directly into an electrical signal, which can achieve higher spatial resolution, improved iodine signal, radiation dose reduction, artifact reduction, and multienergy imaging. This review introduces the technical principles of PCCT, and summarizes its first-in-human experience and current applications in clinical settings, and discusses the future prospects of PCCT.

Ultrashort Echo-Time Magnetic Resonance Imaging Sequence in the Assessment of Systemic Sclerosis-Interstitial Lung Disease

PURPOSE

To test respiratory-triggered ultrashort echo-time (UTE) Spiral VIBE-MRI sequence in systemic sclerosis-interstitial lung disease assessment compared with computed tomography (CT).

MATERIAL AND METHODS

Fifty four SSc patients underwent chest CT and UTE (1.5 T). Two radiologists, independently and in consensus, verified ILD presence/absence and performed a semiquantitative analysis (sQA) of ILD, ground-glass opacities (GGO), reticulations and honeycombing (HC) extents on both scans. A CT software quantitative texture analysis (QA) was also performed. For ILD detection, intra-/inter-reader agreements were computed with Cohen K coefficient. UTE sensitivity and specificity were assessed. For extent assessments, intra-/inter-reader agreements and UTE performance against CT were computed by Lin's concordance coefficient (CCC).

RESULTS

Three UTE were discarded for low quality, 51 subjects were included in the study. Of them, 42 QA segmentations were accepted. ILD was diagnosed in 39/51 CT. UTE intra-/inter-reader K in ILD diagnosis were 0.56 and 0.26. UTE showed 92.8% sensitivity and 75.0% specificity. ILD, GGO, and reticulation extents were 14.8%, 7.7%, and 7.1% on CT sQA and 13.0%, 11.2%, and 1.6% on CT QA. HC was <1% and not further considered. UTE intra-/inter-reader CCC were 0.92 and 0.89 for ILD extent and 0.84 and 0.79 for GGO extent. UTE RET extent intra-/inter-reader CCC were 0.22 and 0.18. UTE ILD and GGO extents CCC against CT sQA and QA were ≥0.93 and ≥0.88, respectively. RET extent CCC were 0.35 and 0.22 against sQA and QA, respectively.

CONCLUSION

UTE Spiral VIBE-MRI sequence is reliable in assessing ILD and GGO extents in systemic sclerosis-interstitial lung disease patients.

Basic HRCT patterns in diffuse interstitial lung disease

The term interstitial lung disease (also called diffuse infiltrative lung disease) encompasses a heterogeneous group of processes characterized by the appearance of an inflammatory reaction in the alveolar wall that can be triggered by different antigens. This group of diseases represents a wide spectrum of processes of diverse etiologies, and sometimes the nomenclature can be confusing. High-resolution computed tomography (HRCT) is the imaging method of choice for the evaluation and diagnosis of interstitial lung diseases because it confirms the presence of lung disease and establishes the correct diagnosis for associated complications. Nevertheless, the definitive diagnosis of these entities requires the imaging findings to be interpreted together with their clinical manifestations and histological confirmation. In this group of diseases, HRCT findings play a fundamental role, being especially important for avoiding unnecessary biopsies. For these reasons, clinicians need to be familiar with the basic radiologic patterns associated with this group of lung diseases: septal, reticular, nodular, ground-glass, cystic, and consolidations. This chapter describes the features of these patterns and ways that they can present, and it reviews some of the most common interstitial lung diseases, emphasizing the predominant radiologic patterns in each of them.

A high-resolution 3D atlas of the spectrum of tuberculous and COVID-19 lung lesions

Our current understanding of the spectrum of TB and COVID-19 lesions in the human lung is limited by a reliance on low-resolution imaging platforms that cannot provide accurate 3D representations of lesion types within the context of the whole lung. To characterize TB and COVID-19 lesions in 3D, we applied micro/nanocomputed tomography to surgically resected, postmortem, and paraffin-embedded human lung tissue. We define a spectrum of TB pathologies, including cavitary lesions, calcium deposits outside and inside necrotic granulomas and mycetomas, and vascular rearrangement. We identified an unusual spatial arrangement of vasculature within an entire COVID-19 lobe, and 3D segmentation of blood vessels revealed microangiopathy associated with hemorrhage. Notably, segmentation of pathological anomalies reveals hidden pathological structures that might otherwise be disregarded, demonstrating a powerful method to visualize pathologies in 3D in TB lung tissue and whole COVID-19 lobes. These findings provide unexpected new insight into the spatial organization of the spectrum of TB and COVID-19 lesions within the framework of the entire lung.

Chest high-resolution computed tomography can make higher accurate stages for thoracic sarcoidosis than X-ray

Background

To explore if chest high-resolution computed tomography (HRCT) can make higher accurate stages for thoracic sarcoidosis stage than X-ray (CRX) only.

Methods

Clinical data from medical records of consecutive patients with a confirmed diagnosis of pulmonary sarcoidosis at Shanghai Pulmonary Hospital from January 1 2012 to December 31 2016 and consecutive patients treated at the Sarcoidosis Center of University of Cincinnati Medical Center, Ohio, USA from January 1 2010 to December 31 2015 were reviewed. The clinical records of 227 patients diagnosed with sarcoidosis (140 Chinese and 87 American) were reviewed. Their sarcoidosis stage was determined by three thoracic radiologists based on CXR and HRCT presentations, respectively. The stage determined from CXR was compared with that determined from HRCT.

Results

Overall, 50.2% patients showed discordant sarcoidosis stage between CXR and HRCT (52.9% in Chinese and 44.8% in American, respectively). The primary reason for inconsistent stage between CXR and HRCT was failure to detect mediastinal lymph node enlargement in the shadow of the heart in CXR (22.1%) and small nodules because of the limited resolution of CXR (56.6%). Stage determined from HRCT negatively correlated with carbon monoxide diffusing capacity (DLCO) significantly (P < .01) but stage determined from CXR did not. Pleural involvement was detected by HRCT in 58 (25.6%) patients but only in 17 patients (7.5%) by CXR. Patients with pleural involvement had significantly lower forced vital capacity and DLCO than patients without it (both P < .05).

Conclusion

Revised staging criteria based on HRCT presentations included 5 stages with subtypes in the presence of pleural involvement were proposed. Thoracic sarcoidosis can be staged more accurately based on chest HRCT presentations than based on CXR presentations. Pleural involvement can be detected more accurately by HRCT.

COVID-19 pneumonia: current evidence of chest imaging features, evolution and prognosis

COVID-19 pneumonia represents a global threatening disease, especially in severe cases. Chest imaging, with X-ray and high-resolution computed tomography (HRCT), plays an important role in the initial evaluation and follow-up of patients with COVID-19 pneumonia. Chest imaging can also help in assessing disease severity and in predicting patient’s outcome, either as an independent factor or in combination with clinical and laboratory features. This review highlights the current knowledge of imaging features of COVID-19 pneumonia and their temporal evolution over time, and provides recent evidences on the role of chest imaging in the prognostic assessment of the disease.

Comparative analysis of density histograms and visual scores in incremental and volumetric high-resolution computed tomography of the chest in idiopathic pulmonary fibrosis patients

Background

Volumetric high-resolution computed tomography (HRCT) of the chest has recently replaced incremental CT in the diagnostic workup of idiopathic pulmonary fibrosis (IPF). Concomitantly, visual and quantitative scores have been proposed for disease extent assessment to ameliorate disease management.

Purpose

To compare the performance of density histograms (mean lung attenuation, skewness, and kurtosis) and visual scores, along with lung function correlations, in IPF patients submitted to incremental or volumetric thorax HRCT.

Material and methods

Clinical data and CT scans of 89 newly diagnosed and therapy-naive IPF patients were retrospectively evaluated.

Results

Forty-six incremental and 43 volumetric CT scans were reviewed. No differences of density histograms and visual scores estimates were found by comparing two HRCT techniques, with an optimal inter-operator agreement (concordance correlation coefficient >0.90 in all instances). Single-breath diffusing lung capacity for carbon monoxide (DLCO_sb) was inversely related with the Best score (r = −00.416; p = 0.014), the Kazerooni fibrosis extent (r = −0.481; p = 0.004) and the mean lung attenuation (r = −0.382; p = 0.026), while a positive correlation was observed with skewness (r = 0.583; p = 0.001) and kurtosis (r = 0.543; p = 0.001) in the incremental HRCT sub-group. Similarly, in the volumetric CT sub-cohort, DLCO_sb was significantly associated with skewness (r = 0.581; p = 0.007) and kurtosis (r = 0.549; p = 0.018). Correlations with visual scores were not confirmed. Forced vital capacity significantly related to all density indices independently on HRCT technique.

Conclusions

Density histograms and visual scores similarly perform in incremental and volumetric HRCT. Density quantification displays an optimal reproducibility and proves to be superior to visual scoring as more strongly correlated with lung function.

Ultra high-resolution computed tomography with 1024-matrix: Comparison with 512-matrix for the evaluation of pulmonary nodules

PURPOSE

To determine whether a 1024-matrix provides superior image quality for the evaluation of pulmonary nodules.

MATERIALS AND METHODS

Prospective evaluation conducted between December 2017 and April 2018, during which CT images showing lung nodules of more than 6 mm and less than 30 mmm were reconstructed with 2 different protocols: 0.5-mm thickness, 512 × 512 matrix, 34.5-cm field of view (FOV) (0.5-512 protocol); and 2-mm thickness, 1024 × 1024 matrix, 34.5-cm FOV (2-1024 protocol). Lung nodule characteristics such as margin, lobulation, pleural indentation, spiculation as well as peripheral vessels and bronchioles visibility and overall image quality were evaluated by three chest radiologists, using a 5-point scale. Image noise was evaluated by measuring the standard deviation in the region of interest for each image.

RESULTS

A total of 89 nodules were evaluated. The 2-1024 protocol performed significantly better for the subjective evaluation of pulmonary nodules (p = 0.006 ∼ p < 0.0001). However, image noise was significantly higher both subjectively and objectively (p = 0.036, p < 0.0001).

CONCLUSION

The use of a 2-1024 protocol does not increase the amount of images and allows better assessment of pulmonary nodules, despite noise increase.

Imaging of Diffuse Lung Disease in the Intensive Care Unit Patient

There is a wide variety of causes of diffuse lung disease in the intensive care unit patient, of which adult respiratory distress syndrome is the commonest clinical consideration. Plain radiography, computed tomography, and ultrasound can be used synergistically to evaluate patients with diffuse lung disease and respiratory impairment. Imaging is not limited to characterization of the cause of diffuse lung disease but also aids in monitoring its evolution and in ventilator setting management.

Ground Glass Lesions on Chest Imaging: Evaluation of Reported Incidence in Cancer Patients Using Natural Language Processing

BACKGROUND

Ground glass opacities (GGOs) on computed tomography (CT) have gained significant recent attention, with unclear incidence and epidemiologic patterns. Natural language processing (NLP) is a powerful computing tool that collects variables from unstructured data fields. Our objective was to characterize trends of GGO detection using NLP.

METHODS

Patients were identified at a large quaternary referral center who underwent chest CT from 2000 to 2016 via query of institutional databases. NLP was used to identify imaging reports with GGOs and to obtain additional demographic data. Incidence of reported GGOs was tracked over time. Multivariate regression was used to identify predictors of GGOs identified on chest CT.

RESULTS

A total of 244,391 chest CTs were included, with 35,386 (14.5%) revealing GGOs. There was a significant relationship between advancing year of chest CT and likelihood of reported GGOs (p < 0.001). GGOs were more likely to occur in older subjects (60.5 vs 58.5 years, p < 0.001), males (54.6% vs 51.5%, p < 0.001), and nonwhite races (21.2% Asian, 15.6% Hispanic, 14.4% black, 14.0% white; p < 0.001). Certain occupational histories predicted more frequent GGOs (p < 0.001), including transportation labor (47.4%), metal workers (42.3%), iron workers (33.3%), cabinetry (32.6%), and foremen (29.6%). Multivariate regression revealed age, sex, nonsmokers, increasing year of chest CT, and race as significant independent predictors of identifying GGOs.

CONCLUSIONS

NLP explored a large cohort of patients who underwent chest CT over the study period. Demographic features predicting reported GGOs include age, sex, race, and occupation. GGO recognition continues to increase with time, and further studies investigating etiology and prognostic implications are necessary.

Recognition of Small Airways Obstruction in Asthma and COPD - The Road Less Travelled

The small airways, once regarded as the silent zone in the air conducting system of the lungs are now known to be one of the initial sites of involvement in diseases like asthma and Chronic Obstructive Pulmonary Disease (COPD). Identification of the involvement of distal airways in these diseases is often difficult to assess, clinically as well as by conventional pulmonary function tests and therefore, usually remains undiscovered in early stages. Early recognition of their involvement in asthma and COPD and timely management may reduce long term morbidity in these conditions. This article aims to highlight the relatively lesser recognized facts about small airways involvement in asthma and COPD and role of imaging and newer modalities for detection.

Role of Computed Tomography in Pediatric Chest Conditions

CT is the preferred cross-sectional imaging modality for detailed evaluation of anatomy and pathology of the lung and tracheobronchial tree, and plays a complimentary role in the evaluation of certain chest wall, mediastinal, and cardiac abnormalities. The article provides an overview of indications and different types of CT chest, findings in common clinical conditions, and briefly touches upon the role of each team member in optimizing and thus reducing radiation dose.

Feasibility of Single Scan for Simultaneous Evaluation of Regional Krypton and Iodine Concentrations with Dual-Energy CT: An Experimental Study

Purpose To evaluate the feasibility of a simultaneous single scan of regional krypton and iodine concentrations by using dual-energy computed tomography (CT). Materials and Methods The study was approved by the institutional animal experimental committee. An airway obstruction model was first made in 10 beagle dogs, and a pulmonary arterial occlusion was induced in each animal after 1 week. For each model, three sessions of dual-energy CT (80% krypton ventilation [krypton CT], 80% krypton ventilation with iodine enhancement [mixed-contrast agent CT], and iodine enhancement [iodine CT]) were performed. Krypton maps were made from krypton and mixed-contrast agent CT, and iodine maps were made from iodine and mixed-contrast agent CT. Observers measured overlay Hounsfield units of the diseased and contralateral segments on each map. Values were compared by using the Wilcoxon signed-rank test. Results In krypton maps of airway obstruction, overlay Hounsfield units of diseased segments were significantly decreased compared with those of contralateral segments in both krypton and mixed-contrast agent CT (P = .005 for both). However, the values of mixed-contrast agent CT were significantly higher than those of krypton CT for both segments (P = .005 and .007, respectively). In iodine maps of pulmonary arterial occlusion, values were significantly lower in diseased segments than in contralateral segments for both iodine and mixed-contrast agent CT (P = .005 for both), without significant difference between iodine and mixed-contrast agent CT for both segments (P = .126 and .307, respectively). Conclusion Although some limitations may exist, it might be feasible to analyze regional krypton and iodine concentrations simultaneously by using dual-energy CT. ^© RSNA, 2016.

Imaging in occupational and environmental lung disease

PURPOSE OF REVIEW

Work-related and environmental lung disease is increasing over time and new antigens causing pulmonary response are described in medical literature every year with more or less specific imaging findings. The purposes of this review are to highlight the current role of imaging, describe classic as well as uncommon high-resolution computed tomography (HRCT) patterns helpful in guiding diagnosis and update the recent literature on this topic.

RECENT FINDINGS

Recent literature on imaging of occupational and environmental lung disease is scarce and is predominantly based on the HRCT appearance related to specific antigen exposure and on prognostic significance of findings.

SUMMARY

Knowledge of imaging modality potential and radiologic appearance may guide identification, characterization and follow-up of old and new occupational and environmental lung diseases. HRCT plays a key role in this context, having radiation exposure as a major limitation, especially in asymptomatic patients. Low-dose HRCT has the potential to be employed for screening and surveillance of the exposed individuals. However, future research is needed to further this field.

Pulmonary Langerhans cell histiocytosis: the many faces of presentation at initial CT scan

Objectives

Pulmonary Langerhans cell histiocytosis (PLCH) is a rare interstitial granulomatous disease that usually affects young adults who are smokers. Chest computed tomography (CT) allows a confident diagnosis of PLCH only in typical presentation, when nodules, cavitated nodules and cysts coexist and predominate in the upper and middle lungs.

Methods

This article includes a pictorial essay of typical and atypical presentations of PLCH at initial chest CT. Various appearances of PLCH are illustrated and possible differential diagnosis is discussed.

Results

PLCH can present with some aspecific features that may cause diagnosis of the initial disease to be overlooked or other pulmonary diseases to be suspected. In cases of nodule presentation alone, the main differential diagnosis should include lung metastasis, tuberculosis and other infections, sarcoidosis, silicosis and Wegener’s disease. In cases of cysts alone, the most common diseases to be differentiated are centrilobular emphysema and lymphangiomyomatosis. Clinical symptoms are usually non-specific, although a history of cigarette smoking, coupled with the presence of typical or suggestive findings at imaging, is key to suspecting the disease. Atypical presentations require surgical biopsy for diagnosis.

Conclusions

The radiologist should be familiar with PLCH imaging features to correctly diagnose the disease or need for further investigation.

Teaching Points

• PLCH is a rare interstitial smoking-related disease that usually affects young adults.

• The typical first CT shows a mix of nodules, cavitary nodules and cysts in the upper-middle lungs.

• Atypical appearance, either cysts or nodules alone, mandates that other diagnoses be considered.

• Lung cystic involvement correlates with lung function abnormalities and predicts functional decline.

• Integration of the clinical history and imaging results is key to diagnosis.

Static end-expiratory and dynamic forced expiratory tracheal collapse in COPD

AIM

To determine the range of tracheal collapse at end-expiration among chronic obstructive pulmonary disease (COPD) patients and to compare the extent of tracheal collapse between static end-expiratory and dynamic forced-expiratory multidetector-row computed tomography (MDCT).

MATERIALS AND METHODS

After institutional review board approval and obtaining informed consent, 67 patients meeting the National Heart, Lung, and Blood Institute (NHLBI)/World Health Organization (WHO) Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria for COPD were sequentially imaged using a 64-detector-row CT machine at end-inspiration, during forced expiration, and at end-expiration. Standardized respiratory coaching and spirometric monitoring were employed. Mean percentage tracheal collapse at end-expiration and forced expiration were compared using correlation analysis, and the power of end-expiratory cross-sectional area to predict excessive forced-expiratory tracheal collapse was computed following construction of receiver operating characteristic (ROC) curves.

RESULTS

Mean percentage expiratory collapse among COPD patients was 17 ± 18% at end-expiration compared to 62 ± 16% during forced expiration. Over the observed range of end-expiratory tracheal collapse (approximately 10-50%), the positive predictive value of end-expiratory collapse to predict excessive (≥80%) forced expiratory tracheal collapse was <0.3.

CONCLUSION

COPD patients demonstrate a wide range of end-expiratory tracheal collapse. The magnitude of static end-expiratory tracheal collapse does not predict excessive dynamic expiratory tracheal collapse.

Quantitative computerized two-point correlation analysis of lung CT scans correlates with pulmonary function in pulmonary sarcoidosis

BACKGROUND

Chest CT scans are commonly used to clinically assess disease severity in patients presenting with pulmonary sarcoidosis. Despite their ability to reliably detect subtle changes in lung disease, the utility of chest CT scans for guiding therapy is limited by the fact that image interpretation by radiologists is qualitative and highly variable. We sought to create a computerized CT image analysis tool that would provide quantitative and clinically relevant information.

METHODS

We established that a two-point correlation analysis approach reduced the background signal attendant to normal lung structures, such as blood vessels, airways, and lymphatics while highlighting diseased tissue. This approach was applied to multiple lung fields to generate an overall lung texture score (LTS) representing the quantity of diseased lung parenchyma. Using deidentified lung CT scan and pulmonary function test (PFT) data from The Ohio State University Medical Center's Information Warehouse, we analyzed 71 consecutive CT scans from patients with sarcoidosis for whom simultaneous matching PFTs were available to determine whether the LTS correlated with standard PFT results.

RESULTS

We found a high correlation between LTS and FVC, total lung capacity, and diffusing capacity of the lung for carbon monoxide (P &lt; .0001 for all comparisons). Moreover, LTS was equivalent to PFTs for the detection of active lung disease. The image analysis protocol was conducted quickly (&lt; 1 min per study) on a standard laptop computer connected to a publicly available National Institutes of Health ImageJ toolkit.

CONCLUSIONS

The two-point image analysis tool is highly practical and appears to reliably assess lung disease severity. We predict that this tool will be useful for clinical and research applications.

Technical parameters and interpretive issues in screening computed tomography scans for lung cancer

Lung cancer screening computed tomographies (CTs) differ from traditional chest CT scans in that they are performed at very low radiation doses, which allow the detection of small nodules but which have a much higher noise content than would be acceptable in a diagnostic chest CT. The technical parameters require a great deal of attention on the part of the user, because inappropriate settings could result in either excess radiation dose to the large population of screened individuals or in low-quality images with impaired nodule detectability. Both situations undermine the main goal of the screening program, which is to detect lung nodules using as low a radiation dose as can reasonably be achieved. Once an image has been obtained, there are unique interpretive issues that must be addressed mainly because of the very high noise content of the images and the high prevalence of incidental findings in the chest unrelated to the sought-after pulmonary nodules.

Paediatric multi-detector row chest CT: what you really need to know

Background

The emergence of multi-detector row CT (MDCT) has established and extended the role of CT especially in paediatric chest imaging. This has altered the way in which data is acquired and is perceived as the 'gold standard' in the detection of certain chest pathologies. The range of available post-processing tools provide alternative ways in which CT images can be manipulated for review and interpretation in order to enhance diagnostic accuracy.

Methodology

Paediatric imaging technique/protocol together with radiation dose reduction is discussed in detail. The use of different post-processing tools to best demonstrate the wide range of important congenital anomalies and thoracic pathologies is outlined and presented pictorially.

Conclusion

MDCT with its isotropic resolution and fast imaging acquisition times reduces the need for invasive diagnostic investigations. However, users must be vigilant in their imaging techniques to minimise radiation burden, whilst maintaining good image quality.

Main Messages

• CT examinations should be clinically justified by the referring clinician and radiologist.

• MDCT is invaluable for evaluating the central airway, mediastinal structures and lung parenchyma.

• MDCT is more sensitive than plain radiographs in detection of structural changes within the lungs.

Bronchiolitis and bronchial disorders in interstitial lung disease

PURPOSE OF REVIEW

Bronchial and bronchiolar abnormalities in interstitial lung diseases (ILDs) are an issue often underestimated. However, new interstitial patterns with bronchiolar involvement are being described and the concept is still evolving. The scope of this review is to introduce a comprehensive approach to airway disorders in the context of ILDs, mainly from a pathologic perspective.

RECENT FINDINGS

Recent studies have revealed significant inflammatory and structural alterations at the level of small airways in idiopathic interstitial pneumonias, which may participate in the lung-remodeling pathogenetic process. A suggested pathogenetic role of cigarette smoking for lung-remodeling in smoking-related ILDs is further investigated, and unclassified fibrosis as a prominent feature in lung biopsy specimens of smokers has been established. New targeted therapies for lymphangioleiomyomatosis based on molecular and biologic properties of the disease are currently undergoing clinical trials. Combined pharmaceutical and interventional therapeutic regimens are of growing concern for refractory airway lesions in sarcoidosis. The application of volumetric high-resolution computed tomography (HRCT) chest scanning with acquisition of expiratory images provides valuable information about the involvement of small airways in ILDs.

SUMMARY

The imaging and pathologic focus on airway abnormalities in ILDs make them an integral part of their pathology with a significant pathogenetic role in interstitial processes and variable contribution to the functional status of patients.

High-resolution computed tomography quantitation of emphysema is correlated with selected lung function values in stable COPD

BACKGROUND

The literature shows conflicting results when high-resolution computed tomography (HRCT) scores of emphysema were correlated with different indices of airflow obstruction.

OBJECTIVES

We correlated HRCT scores of emphysema with different indices of airflow obstruction.

METHODS

We performed HRCT of the chest in 59 patients, all smokers or ex-smokers, with stable chronic obstructive pulmonary disease of different severity [GOLD stages I-IV; mean age ± SD 67.8 ± 7.3 years; pack/years 51.0 ± 34.6; percent predicted forced expiratory volume in 1 s (FEV(1)% predicted) 52.3 ± 17.6; post-bronchodilator FEV(1)% predicted 56.5 ± 19.1; FEV(1)/forced vital capacity (FVC) ratio 50.8 ± 10.2; post-bronchodilator FEV(1)/FVC ratio 51.6 ± 11.0; percent diffusion lung capacity for carbon monoxide (DLCO%) 59.2 ± 21.1; DLCO/percent alveolar volume (VA%) 54.5 ± 18.2; percent residual volume 163.0 ± 35.6; percent total lung capacity (TLC%) 113.2 ± 15; residual volume/TLC 1.44 ± 0.2]. All patients were in stable phase.

RESULTS

The mean ± SD visual emphysema score in all patients was 25.6 ± 25.4%. There was a weak but significant correlation between the percentage of pulmonary emphysema and numbers of pack/years (R = +0.31, p = 0.024). The percentage of emphysema was inversely correlated with the FEV(1)/FVC ratio before and after bronchodilator use (R = -0.44, p = 0.002, and R = -0.39, p = 0.005), DLCO% (R = -0.64, p = 0.0003) and DLCO/VA% (R = -0.68, p < 0.0001). A weak positive correlation was also found with TLC% (R = +0.28, p = 0.048). When patients with documented emphysema were considered separately, the best significant correlation observed was between DLCO/VA% and HRCT scan score (p = 0.007).

CONCLUSIONS

These data suggest that in patients with stable chronic obstructive pulmonary disease of varying severity, the presence of pulmonary emphysema is best represented by the impaired gas exchange capability of the respiratory system.