Airways DiseaseAirways Disease

Sujal R DesaiSujal R DesaiKingKing’’s College Hospital, London, UKs College Hospital, London, UK

Norwegian Society of Thoracic ImagingOslo, October 2011

Opening Statements…Disease of the airways (particularly the “small” airways) are common

Imaging has an important role in Ix of patients with suspected airways disease

Many advantages of plain chest radiography but also significant limitations

Significant advance in imaging and understanding of airway diseases with high-resolution CT and more recently MD-CT

Aims

• To discuss the merits and demerits of imaging tests in Ix of airways diseases

• To consider the anatomy relevant to HRCT imaging of airways disease

• To review imaging features of not only some “well-known” but also less appreciated causes of airways diseases

Airway DimensionTotal Cross-Sectional Area

AREA (AREA (cmcm22))

TracheaTrachea 5.05.0BronchiBronchi

SegmentalSegmental 3.23.2SubsegmentalSubsegmental 3.23.2

BronchiolesBronchiolesTerminalTerminal 116116RespiratoryRespiratory 10001000

From: Bates DV et al. In: From: Bates DV et al. In: Respiratory Function in Disease Respiratory Function in Disease (1971)(1971)

•• Small airways (diameter < 2mm); Small airways (diameter < 2mm); effectively the effectively the terminal bronchiole and beyondterminal bronchiole and beyond……

•• Peripheral small airways contribute Peripheral small airways contribute littlelittle to normal to normal airflow obstructionairflow obstruction

•• The The ““silent zonesilent zone”” of the lungsof the lungs

Hogg JC et al. Site and nature of airway obstruction in chronic obstructive lung disease. N Engl J Med 1968;278:1355-1360

The Small Airways

Small Airway AnatomySmall Airway Anatomy

Disease of the Airways

LARGEBronchiectasis

SMALLConstrictive Obliterative Bronchiolitis“Exudative” bronchiolitis / DPB

Respiratory bronchiolitis associated ILDFollicular bronchiolitisMineral dust-associated airways disease

SarcoidosisExtrinsic Allergic AlveolitisMicrocarcinoid tumourlets

Imaging ModalitiesImaging Modalities

•• (Bronchography (Bronchography -- R.I.P)R.I.P)

•• Chest RadiographyChest Radiography (( ))

•• Computed TomographyComputed Tomography

BronchiectasisBronchiectasis

BronchiectasisBronchiectasisDefinitionsDefinitions

Pathology:Pathology:““Abnormal, Abnormal, ‘‘permanentpermanent’’ dilatation of bronchi (airways with cartilage and dilatation of bronchi (airways with cartilage and [usually] bronchial mucous glands in their walls)[usually] bronchial mucous glands in their walls)””

WMWM ThurlbeckThurlbeck ““Pathology of the LungPathology of the Lung”” (1995)(1995)

Radiology:Radiology:““Abnormal [permanent] bronchial dilatation (compared with the Abnormal [permanent] bronchial dilatation (compared with the accompanying pulmonary artery), with or without bronchial wall taccompanying pulmonary artery), with or without bronchial wall thickeninghickening””

Naidich et al. Computed tomography of bronchiectasis. J Comput Assist Tomogr 1982;6:437-444

♦♦ High Spatial ResolutionHigh Spatial Resolution♦♦ Cheap Cheap ♦♦ Technical simplicityTechnical simplicity♦♦ Low radiation doseLow radiation dose

♦♦ Anatomical superimpositionAnatomical superimposition♦♦ Limited contrast resolutionLimited contrast resolution♦♦ Operator (radiographer) dependenceOperator (radiographer) dependence

BronchiectasisBronchiectasisAdvantages and Disadvantages of CXRAdvantages and Disadvantages of CXR

Roentgenologic Diagnosis of BronchiectasisRoentgenologic Diagnosis of Bronchiectasis“…“… abnormal chest radiograph in vast majority (93%) of patients wiabnormal chest radiograph in vast majority (93%) of patients with th bronchographicallybronchographically--proven bronchiectasisproven bronchiectasis””

Gudbjerg et al Acta Radiologica (1955)Gudbjerg et al Acta Radiologica (1955)

Improved Plain Film Criteria for the Diagnosis of Improved Plain Film Criteria for the Diagnosis of BronchiectasisBronchiectasis

Woodring JH J Kentucky Med Assoc 1994Woodring JH J Kentucky Med Assoc 1994

BronchiectasisBronchiectasisUtility of Plain Chest RadiographyUtility of Plain Chest Radiography

Currie et al Currie et al ThoraxThorax 19871987Currie et al Currie et al Clinical Radiology Clinical Radiology 19871987Cooke et al Cooke et al Thorax Thorax 19871987

“…in general, CXR diagnosis of bronchiectasis limited by poor sensitivity and specificity”

BronchiectasisBronchiectasisUtility of Plain Chest RadiographyUtility of Plain Chest Radiography

•• Early data on value of CT in diagnosis of Bx variable, Early data on value of CT in diagnosis of Bx variable, butbut……

Different technical parameters in different studiesDifferent technical parameters in different studies?Reliability of bronchography?Reliability of bronchographyLimited HRCT dataLimited HRCT data

•• HRCT HRCT --vsvs-- PathologyPathology

BronchiectasisBronchiectasisUtility of Computed TomographyUtility of Computed Tomography

•• ThinThin--section CT findings compared with (section CT findings compared with (surgicalsurgical) pathological ) pathological findingsfindings

47 lobes with pathological Bx;47 lobes with pathological Bx; 41/47 identified on HRCT41/47 identified on HRCT

♦♦ Lack of tapering Lack of tapering 37/4137/41♦♦ Wall thickeningWall thickening 32/4132/41♦♦ Bronchi visible in lung peripheryBronchi visible in lung periphery 21/4121/41

nb nb SurgicalSurgical series, thus series, thus ““severesevere”” disease in most casesdisease in most cases

Kang et al. Bronchiectasis: comparison of preoperative thin-section CT and pathologic findings in resected specimens Radiology1995;195:649-654

Bronchiectasis Bronchiectasis Utility of Computed TomographyUtility of Computed Tomography

Bronchiectasis Bronchiectasis CT SignsCT Signs

VERTICALLY ORIENTATEDSignet Rings

IN-PLANETramlines

BRONCHIAL CROWDINGVOLUME LOSSMOSAIC ATTENUATIONThickened interlobular septa

AIRWAY PLUGGINGBronchocoeles / “Tree-in-Bud” pattern

•• Airways too central or close to a carinaAirways too central or close to a carina•• ArtefactualArtefactual11 Movement, Movement, ““twinkling starstwinkling stars””

•• Age (>65) Age (>65) 22

•• High Altitude High Altitude 33

•• ““Hypoxic bronchoHypoxic bronchodilatationdilatation”” 44

•• Other diagnoses Other diagnoses LCH, Adenocarcinoma, Traction BxLCH, Adenocarcinoma, Traction Bx

1 1 Kuhns LR and Borlaza G. The “Twinkling Star” sign. An aid in differentiating pulmonary vessels from pulmonary nodules on computed tomograms Radiology 1980;135:763-76422 Matsuoka S et al. Bronchoarterial ratio and bronchial wall thickness on high-resolution CT in asymptomatic subjects: correlation with age and smoking. AJR Am J Roentgenol 2003;180:513-5183 3 Lynch DA et al. Uncomplicated asthma in adults: comparison of CT appearance of the lungs in asthmatic and healthy subjects. Radiology 1993;188:82944 Remy-Jardin M et al. Airway changes in chronic pulmonary embolism: CT findings in 33 patients. Radiology 1997;203:355

BronchiectasisBronchiectasisCT False Positive DiagnosesCT False Positive Diagnoses

Matsuoka S et al. Bronchoarterial ratio and bronchial wall thickness on high-resolution CT in asymptomatic subjects: correlation with age and smoking AJR Am J Roentgenol 2003;180:513-518

Small Airways DiseaseSmall Airways Disease

•• (Constrictive) obliterative bronchiolitis(Constrictive) obliterative bronchiolitis•• Bronchiolitis obliteransBronchiolitis obliterans•• Proliferative bronchiolitisProliferative bronchiolitis•• Cellular bronchiolitisCellular bronchiolitis•• BOOPBOOP•• Exudative bronchiolitisExudative bronchiolitis

Small Airways DiseaseSmall Airways Disease(Confusing) Terminology(Confusing) Terminology……!!

Small Airways DiseaseSmall Airways Disease(Simplified) Terminology(Simplified) Terminology……!!

Hansell DM Small Airways Disease: Detection and Insights with Computed Tomography Eur Respir J 2001;17:1294

•• (Constrictive) obliterative bronchiolitis(Constrictive) obliterative bronchiolitis

•• Exudative bronchiolitisExudative bronchiolitis

CONSTRICTIVE

EXUDATIVE

Small Airways DiseaseSmall Airways DiseaseCT Signs of Constrictive & Exudative Airways DiseaseCT Signs of Constrictive & Exudative Airways Disease

CONSTRICTIVE OBMosaic attenuation pattern

(INDIRECT)

EXUDATIVE BRONCHIOLITIS“Tree-in-Bud” pattern

(DIRECT)

• Viral respiratory tract infection RSV, Parainfluenza

• Toxic Fume Inhalation Nitrous Fumes, Sulphur Dioxide

• Mineral Dust Exposure• Connective Tissue Diseases esp. RhA, Sjögren’s

• Post-transplantation Heart-Lung, Lung, Bone marrow

• Bronchiectasis Cystic Fibrosis

• Drugs Penicillamine

• Cryptogenic

Adapted from: King TE Jr. Bronchiolitis. In: Interstitial lung Diseases (1998) 3rd Edn. Schwarz MI, King TE (Eds)

Constrictive Obliterative BronchiolitisConstrictive Obliterative BronchiolitisAetiologies Aetiologies

CARDINAL CT FEATURESAreas of decreased attenuationReduced number / calibre of vesselsBronchial dilatationNo parenchymal distortion (cf emphysema)

Constrictive Obliterative Bronchiolitis Constrictive Obliterative Bronchiolitis CT Signs of Constrictive OBCT Signs of Constrictive OB

Constrictive Obliterative Bronchiolitis Constrictive Obliterative Bronchiolitis EndEnd--Expiratory CTExpiratory CT

Constrictive Obliterative Bronchiolitis Constrictive Obliterative Bronchiolitis EndEnd--Expiratory CTExpiratory CT

inspEXP

Courtesy of Dr Tomas Franquet

Constrictive Obliterative Bronchiolitis Constrictive Obliterative Bronchiolitis Lateral Decubitus CTLateral Decubitus CT

Exudative Bronchiolitis“Tree-in-Bud”

Hansell DM. Small Airways Disease: Detection and Insights with Computed Tomography Eur Respir J 2001;17:1294

• Endobronchial spread of infection (e.g. TB)• Non-tuberculous (mycobacterial) infection

• (Japanese) diffuse panbronchiolitis • Aspiration• Connective tissue / Inflammatory bowel diseases• [Tumours (e.g. leukaemia/metastatic)]

Exudative Bronchiolitis Exudative Bronchiolitis CT SignsCT Signs

OthersOthers……!!

Respiratory BronchiolitisRespiratory BronchiolitisAssociated Interstitial Lung DiseaseAssociated Interstitial Lung Disease

1 Niewohner et al Pathological Changes in the Peripheral Airways of Young Cigarette Smokers. N Engl J Med 1974;291:7552 Fraig et al Respiratory Bronchiolitis: a Clinicopathologic Study in Current Smokers, Ex-smokers, and Never Smokers. Am J Surg Pathol 2002;26:647

RB common incidental finding in all smokers 1,2

• Bronchiolocentric inflammation• Pigmented macrophages • Mild fibrosis• ASYMPTOMATIC

RB-ILD = “…clinical manifestation of ILD associated with the pathological lesion of RB”

Respiratory Bronchiolitis Respiratory Bronchiolitis Pathological ConsiderationsPathological Considerations

Respiratory Bronchiolitis Respiratory Bronchiolitis CT FindingsCT Findings

Respiratory Bronchiolitis Respiratory Bronchiolitis CT FindingsCT Findings

CT Features 1,2

GROUND GLASS OPACIFICATIONPatchy, diffuse

CENTRILOBULAR NODULES

EmphysemaParenchymal FibrosisLobular decreased attenuationThickened interlobular septa

1 Moon J et al Clinical Significance of Respiratory Bronchiolitis on Open Lung Biopsy and its Relationship to Smoking Related Interstitial Lung Disease Thorax 1999;54:10092 Heyneman LE et al Respiratory Bronchiolitis, Respiratory Bronchiolitis-Associated Interstitial Lung Disease, and Desquamative Interstitial Pneumonia: Different Entities or Part of the Spectrum of the Same Disease Process? AJR Am J Roentgenol1999;173:1617

Respiratory Bronchiolitis Respiratory Bronchiolitis CT FindingsCT Findings

Follicular BronchiolitisFollicular Bronchiolitis

Reactive Lymphoid Lesions. In: Non-neoplastic disorders of the lower respiratory tract. Travis WD et al eds. (2002) AFIP/ARP, Washington DCHowling SJ et al. Thin-section CT and histologic findings. Radiology 1999;212:637

Follicular Bronchiolitis Follicular Bronchiolitis CT & Pathological FindingsCT & Pathological Findings

SarcoidosisSarcoidosis

Hansell DM et al. Pulmonary sarcoidosis: morphologic associations of airflow obstruction at thin-section CT. Radiology 1998; 209:697

Sarcoidosis Sarcoidosis Airway DiseaseAirway Disease

Hypersensitivity Hypersensitivity PneumonitisPneumonitis

Interstitial infiltrate Lymphocytes and plasma cells, predominantly interstitial; minimal fibrosis [usually peribronchiolar]

Granulomas Small, poorly-formed & non-necrotising within interstitium and air-spaces

Bronchiolitis Variable in extent

Hypersensitivity Pneumonitis Hypersensitivity Pneumonitis Pathological FeaturesPathological Features

Hypersensitivity Pneumonitis Hypersensitivity Pneumonitis CT FeaturesCT Features……Subacute DiseaseSubacute Disease

Hypersensitivity Pneumonitis Hypersensitivity Pneumonitis CT FeaturesCT Features……Chronic DiseaseChronic Disease

Microcarcinoid TumourletsMicrocarcinoid Tumourlets

• Pathology: focal carcinoid-like tumourlets cause bronchiolar scarring

• Clinical: mild to severe irreversible airflow obstruction, no obvious cause

• CXR: overinflated lungs +/- nodules• HRCT: features consistent with constrictive bronchiolitis

and nodules (resembling metastases, may be bronchocentric)

Microcarcinoid Tumourlets Microcarcinoid Tumourlets Neuroendocrine HyperplasiaNeuroendocrine Hyperplasia

Disease of the airways (particularly the “small” airways) are common

CT features of airways diseases varied and dependent on underlying pathological process: constrictive OB (indirect signs) -vs- exudative bronchiolitis (direct signs)

Knowledge of pathological basis of different airways disease is of value in radiological (HRCT) diagnosis

Closing StatementsClosing Statements

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