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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