High Resolution Lung Ct

8/3/2019 High Resolution Lung Ct

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Loma Linda University DiagnosticRadiology

HIGH RESOLUTIONLUNG CT:

Key FindingsKL Fisher MD, FRCP(C)

Department of RadiologyLoma Linda University Medical Center


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INTRODUCTION

With advent of thin collimation on commercialscanners, use of CT for precise anatomic definition ofdiffuse lung disease became possible and was reported

by several authors Use of term high-resolution CTattributed to group that

described potential use for assessing lung disease in1982

First landmark descriptions of HRCT findings reportedby Nakata, Naidich and Zerhouni in 1985


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HRCT DEFINITION

Thin section images (.51.5 mm) obtainedevery 1020 mm through the lungs in fullinspiration

Indications include:

Diffuse interstitial lung disease evaluation

Evaluation of areas of least involvement for biopsy

guidance

Abnormal PFTs with normal CXR


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OBJECTIVES

Review normal lung anatomy on HRCT

Learn how to recognize key findings

Learn what the key findings mean Develop an approach to evaluation of HRCT of

the lung

Application of approach to HRCTinterpretation


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Key HRCT Findings of

Lung Disease

Interlobular septalthickening

Honeycombing

Traction bronchiectasis

Nodules (3 patterns)

Tree-in-bud pattern

Consolidation

Ground-glass opacity

Emphysema

Lung cysts

Mosaic perfusion and airtrapping


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HRCT LUNG ANATOMY

Interstitial fiber system

Large bronchi and arteries

Secondary pulmonary lobule

Interlobular septa and contiguous subpleuralinterstitium

Centrilobular structures

Lobular parenchyma and acini Subpleural interstitium and pleural surfaces


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LUNG INTERSTITIUM

A continuum of looseconnective tissue

throughout the lungs(Weibel)

Axial fiber system

Peripheral fiber system

Septal fiber system


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LARGE BRONCHI and ARTERIES

Closely associated and branch in parallel

Encased by peribronchovascular interstitium

Artery/bronchus ~ 1:1, maximum 1.3:1

Outer walls form smooth and sharply definedinterface with surrounding lung

Thickening of peribronchial and perivascularinterstitium results in irregular interfaces


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Secondary Pulmonary Lobule

(MILLER)

Polyhedral, 12.5 cm indiameter

Comprised of 3 - 5terminal bronchioles

Marginated byinterlobular septa

Centrilobular artery andbronchiole


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INTERLOBULAR SEPTA

Part of interstitial fibersystem described by Weibel

Extend over surface of lung

beneath visceral pleura Contain pulmonary veins

and lymphatics

Usually 12.5 cm in lengthand perpendicular to pleuralsurface


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SECONDARY PULMONARY LOBULE


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Interlobular septa thickest

and most numerous inapical, anterior and lateral

upper lobes, anterior and

lateral middle lobe and

lingula, anterior and

diaphragmatic surfaces oflower lobes and along

mediastinal pleural

surfaces

Thinner and less welldefined in central lung,

difficult to identify on

HRCT


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CENTRILOBULAR

STRUCTURES

Contains pulmonary artery and bronchiolarbranches as well as centrilobular interstitium

HRCT appearance and visibility aredetermined by their size

Secondary pulmonary lobule supplied by

arteries and bronchioles measuring ~ 1 mm indiameter


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Venous arcade withcentrilobular artery


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SUBPLEURAL INTERSTITIUM

and PLEURA

Visceral pleura consists ofsingle layer of flattenedmesothelial cells subtendedby layers of fibroelastic

connective tissue Connective tissue component

generally referred to assubpleural interstitiumonHRCT

Abnormalities most readilyseen in relation to majorfissures


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Lung Disease

Interlobular septal

thickening

Honeycombing Traction bronchiectasis


Tree-in-bud pattern

Consolidation


Emphysema

Lung cysts



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Interlobular Septal Thickening

Reticular pattern

Thickened septa outlinelobules of characteristicsize and shape

12.5 cm in diameter Centrilobular artery

Lymphangitic carcinomatosis


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Interlobular Septal Thickening:

Significance

A few thickened septa are common

Call only when it is the predominant finding

Smooth septal thickening most common, canalso be nodular or beaded

Lymphangitic spread of carcinoma

Lymphoma and leukemia

Pulmonary edema

Amyloidosis (rare)


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Interstitial pulmonary edema


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AMYLOIDOSIS


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Lung Disease


Honeycombing Traction bronchiectasis


Tree-in-bud pattern


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HONEYCOMBING

Cystic lucencies

Air containing

310 mm in diameter

Share walls

Several layers

Usually subpleural


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HONEYCOMBING:

Differential diagnosis

Usual interstitial pneumonia (UIP)

Idiopathic pulmonary fibrosis (IPF)

70% of cases

25% 5 year survival

RA, scleroderma, other collagen vascular diseases

Drugs

Chronic hypersensitivity pneumonitis Asbestosis (uncommon)

End-stage sarcoidosis (uncommon)


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IDIOPATHIC PULMONARY FIBROSIS

CHRONIC EAA


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CHRONIC EAA


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SCLERODERMA


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HONEYCOMBING: Significance

Very important finding in clinical practice

Fibrosis is present

UIP usually the histologic pattern IPF very likely in absence of known disease

Treatment unlikely to be effective

Lung biopsy rarely performed Dont overcall honeycombing


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Lung Disease


Honeycombing

Traction

bronchiectasis

Nodules (3 patterns) Tree-in-bud pattern


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TRACTION BRONCHIECTASIS

Bronchiectasis resultingfrom fibrosis

Corkscrew appearance

Mucous plugging absent Bronchioles may be

involved

Associated with otherfindings of fibrosis(e.g. reticulation)


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TRACTION BRONCHIESTASIS


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TRACTION BRONCHIECTASIS:

Significance

Fibrosis is present

Useful in diagnosis when honeycombing absent

UIP and IPF common causes Other causes of fibrosis (sarcoidosis, HP, NSIP)

more likely than when honeycombing is present

Biopsy may be indicated


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Lung Disease


Honeycombing

Traction bronchiectasis Nodules (3 patterns)

Tree-in-bud pattern

Consolidation


Emphysema

Lung cysts



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NODULES

Rounded opacity, at least moderately welldefined, < 3 cm in diameter

HRCT assessment and differential diagnosisof multiple nodular opacities is based on: Distribution (perilymphatic, random,

centrilobular)

Size (large or small [< 1 cm])Appearance (well-defined or ill-defined)

Attenuation(solid or ground-glass opacity)


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Multiple Nodules

Subpleural nodules No subpleural nodules

Patchy ornon-uniform

Centrilobular

distribution

Diffuse anduniform

Perilymphatic

distribution

SarcoidosisSilicosis

Lymphangitic carc

Random

distribution

Miliary TBHematogenous mets

Diseases involvingsmall airways

or vessels


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NODULES:

Anatomic patterns

Perilymphatic distribution

Random distribution

Centrilobular distribution


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Loma Linda University Diagnostic

Radiology

PERILYMPHATIC NODULES

Located alongbronchovascular bundles,interlobular septa, andpleura including fissures

i.e. Along the distributionof lymphatics


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Radiology


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Radiology

Perilymphatic nodules:


Sarcoidosis (mid and upper lobe predominant)

Tends to have less septal involvement

Lymphangitic spread of tumor (random)

Tends to have predominant septal involvement

Silicosis and CWP (uncommon)

Amyloidosis (rare) Lymphocytic interstitial pneumonitis (LIP) - rare

Coal Workers Pneumoconiosis


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Coal Workers Pneumoconiosis


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Radiology

LYMPHOCYTIC

INTERSTITIALPNEUMONIA


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AMYLOIDOSIS


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Radiology

Perilymphatic nodules: Significance

Sarcoidosis or lymphangitic carcinomatosis verylikely

Clinical history may be sufficient for diagnosis

Asymptomaticsarcoidosis

Hx of carcinoma, dyspnealymphangitic spread

Coal minersilicosis

Bronchoscopic biopsy likely diagnostic forsarcoid and lymphangitic carcinomatosis


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Radiology

RANDOM NODULES

Distribution includescentrilobular and

subpleural location

Distribution is totallyrandom


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Radiology

MILIARY

TUBERCULOSIS


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Radiology

Random Nodules

Miliary TB

Miliary fungal infection

Hematogenous metastases

Sarcoidosis (uncommon)


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Radiology

SARCOIDOSIS


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Radiology

Random nodules: Significance

Metastases or TB very likely, depending onhistory

Bronchoscopy will likely provide diagnostic

material


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Radiology

CENTRILOBULAR NODULES

Reflect bronchiolar orperibronchiolarabnormalities

histologically Separated from pleural

surface, fissures andinterlobular septa by

several mm

H i i i P i i


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Hypersensitivity Pneumonitis

CENTRILOBULAR NODULES


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Radiology

CENTRILOBULAR NODULES:


Endobronchial spread of TB, MAC

Bronchopneumonia

Hypersensitivity pneumonitis

Endobronchial spread of tumor Pneumoconiosis

COP, aka BOOP (rare)

Histiocytosis (rare)

Edema (uncommon)

Vasculitis (uncommon)

Ground glass


Bronchopneumonia


Endobronchial spread of tumor Pneumoconiosis

COP, aka BOOP (rare)

Histiocytosis (rare)

Edema (uncommon)

Vasculitis (uncommon)

Ground glass


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Radiology

RB-ILD


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Radiology

Endobronchial TB


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Radiology

Centrilobular nodules: Significance

Small airways disease most likely

Consider infection

With appropriate history, HRCT findings maybe diagnostic of hypersensitivity pneumonitis

Remember BAC

Transbronchoscopic Bx often diagnosticbecause of relation of nodules to airways

K HRCT Fi di f


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Radiology


Lung Disease


Honeycombing


Tree-in-bud pattern

Consolidation


Emphysema

Lung cysts



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Radiology

Tree-In-Bud: Diagnosis

Dilatation and impactionof centrilobular airways

Resembles a budding

tree Centered 510 cm from

pleural surface

More conspicuous thannormal branching vessels

May be associated withcentrilobular nodules


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Radiology


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Radiology

Tree-In-Bud: Differential diagnosis


Bronchopneumonia

Bronchiectasis

Cystic fibrosis

Panbronchiolitis (rare)

ABPA (rare)

Asthma (rare)

BAC (rare)


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Radiology

S.AureusBronchiolitis

Kartagener s ndrome


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Radiology

Kartagener syndrome

BRONCHOPNEUMONIA


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Radiology


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Radiology

Tree-In-Bud: Significance

Very characteristic appearance

Almost always infection

Diagnosis is in the sputum

Bronchoscopy with washing should bediagnostic



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Radiology


Lung Disease


Honeycombing


Tree-in-bud pattern

Consolidation


Emphysema

Lung cysts



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Radiology

AIRSPACE CONSOLIDATION

Imcreased lung attenuation with obscuration ofunderlying pulmonary vessels

Replacement of alveolar air by fluid, cells, tissue or

other material

Chronic diseases

COP/BOOP, chronic eosinophilic pneumonia

Lymphoma, bronchioloalveolar carcinoma Acute diseases not usually imaged with HRCT

BRONCHOPNEUMONIA


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Radiology

BRONCHOPNEUMONIA


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Radiology

CHRONIC CONSOLIDATION

COP/BOOP

Often has predominant peribronchial or subpleuraldistribution

However, distribution often not specific

Chronic eosinophilic pneumonia

Subpleural areas of consolidation involving mainly

upper lobes


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Radiology

COP

Consolidation : Differential


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Radiology

Consolidation : Differential

Diagnosis

Primary abnornalityddx based on symptoms Chronic symptoms (regardless of what they are)

COP/BOOP

Eosinophilic pneumonia Interstitial pneumonias

Bronchioloalveolar carcinoma (BAC)

Acute symptoms Pneumonia

Acute interstitial pneumonia (AIP)


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PERIBRONCHIOLAR CONSOLIDATION

COP (aka BOOP)


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COP (aka BOOP)


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Radiology

Consolidation: Significance

History important in diagnosis

Acute: pneumonia most likely

Chronic: COP/BOOP, eosinophilic pneumonia,

BAC most important considerations



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Radiology


Lung Disease


Honeycombing


Tree-in-bud pattern

Consolidation


Emphysema

Lung cysts



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Radiology

GROUND GLASS PATTERN

Presence of hazy increased opacity withoutobscuration of underlying vascular markings

Reflects presence of morphologic abnormalitiesbelow resolution of HRCT

Can result from mild interstitial abnormalities,mild alveolar filling or increased blood flow

DDx based on clinical, distribution, and presenceof associated findings


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Radiology

GGO

Chronic lung diseases HP

Diffuse or lower lung zone predominant

Associated with lobular areas of decreased attenuation andair trapping, centrilobular nodules

DIP, AIP

NSIP (CTDs, drug induced lung disease)

Extensive bilateral GGO, fine reticular pattern, tractionbronchiectasis and architectural distortion


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Radiology

Ground Glass Opacity: acute

Pulmonary edema

Hemorrhage

Pneumonia (PCP, viral)

Diffuse alveolar damage (DAD)

Interstitial pneumonias (e.g. AIP)


Methotrexate Drug Toxicity


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Methotrexate Drug Toxicity

Acute Alveolitis


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Radiology

Acute Alveolitis

G d Gl O i Ch i


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Radiology

Ground Glass Opacity: Chronic

Interstitial pneumonias (NSIP, UIP, DIP) Hypersensitivity pneumonitis COP/BOOP Eosinophilic pneumonia BAC Respiratory bronchiolitis-interstitial lung disease (RB-

ILD) Sarcoidosis (uncommon) Lipoid pneumonia (rare) Alveolar proteinosis (rare)

ALVEOLAR PROTEINOSIS


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ALVEOLAR PROTEINOSIS

RESPIRATORY BRONCHIOLITIS-INTERSTITIAL LUNG


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Radiology

DISEASE (RB-ILD)

G d Gl O i Si ifi


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Radiology

Ground Glass Opacity: Significance

Morphologic abnormalities below the resolutionof HRCT

Histology non-specific

Airspace disease in 14% Interstitial disease in 54%

Mixed disease in 32%

Acute symptoms: all have active disease Chronic symptoms: 60-80% have active disease

Pursue diagnosis

D d L O i


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Radiology

Decreased Lung Opacity

Emphysema Centrilobular

Panlobular

Paraseptal Lung cysts

Airway related

Non-airway related



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Radiology

y g

Lung Disease


Honeycombing

Traction bronchiectasis


Tree-in-bud pattern

Consolidation


Emphysema

Lung cysts Mosaic perfusion and

air trapping

TYPES OF EMPHYSEMA


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TYPES OF EMPHYSEMA

Centrilobular Emphysema:


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Radiology

p y

Diagnosis

Common, associated with smoking

Symptoms frequent

Path: areas of emphysema surrounding thecentrilobular bronchiole and artery

HRCT: centrilobular or spotty lucencies

Walls not usually visible

Upper lobe predominance


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Radiology

P l b l E h Di i


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Radiology

Panlobular Emphysema: Diagnosis

Uncommon, alpha-1 antitrypsin deficiency, smokers

Symptoms frequent

Pathology: uniform destruction of secondary

pulmonary lobule HRCT

Diffuse low attenuation

Focal lucencies absent

Pulmonary vessels small

Lower lobe predominance


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Radiology

P t l E h Di i


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Radiology

Paraseptal Emphysema: Diagnosis

Common, occurs as an isolated abnormality orassociated with centrilobular emphysema

Symptoms uncommon, spontaneous

pneumothorax

Path: destruction of subpleural lobules

HRCT: Subpleural lucencies marginated by

interlobular septa and bullae (> 1 cm)

Upper lobe predominance


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Radiology

Giant Bullous Lung Disease


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g

Emph sema Significance


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Radiology

Emphysema Significance

Most diagnosed based on symptoms, obstructivePFTs, abnormal chest radiograph

20% present with findings more typical of

interstitial or vascular disease Normal chest radiographs

Low oxygen diffusing capacity

Normal PFTs (no obstruction)

Lung Volume Reduction Surgery


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Radiology

Lung Volume Reduction Surgery

Resection of emphysematous lung 1218 patients with severe emphysema

Randomized to LVRS or medical treatment

Predominantly upper lobe emphysema, lowexercise capacity Mortality lower with LVRS

Non-upper lobe emphysema, high exercisecapacity Mortality higher with LVRS



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Radiology

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Lung Disease


Honeycombing


Tree-in-bud pattern

Consolidation


Emphysema

Lung cysts Mosaic perfusion and air

trapping

CYSTIC PATTERN


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Radiology

CYSTIC PATTERN

Thin-walled, circumscribedair-containing lesions withinthe lung

Usually reflect honeycombingor air-filled cysts

Distribution and presence ofother features specific to

each disease process allowsdifferential diagnosis

Lung Cysts: Diagnosis


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Radiology

Lung Cysts: Diagnosis

Cyst is a non-specific termAir-filled lesion

Localized

Thin walledWell circumscribed

Larger than 1 cm

Lymphangioleiomyomatosis (LAM)


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Lung Cysts: Differential Diagnosis


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Radiology

Lung Cysts: Differential Diagnosis

Honeycombing Emphysema (bullae)

Cystic bronchiectasis

Pneumatoceles associated with pneumonia Histiocytosis (rare)

Lymphangiolyomyomatosis (LAM) and tuberous

sclerosis (TS) rare Sjogren syndrome with LIP (rare)


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Radiology

Langerhans Cell Histiocytosis

SACCULAR BRONCHIECTASIS


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Radiology

Severe Emphysema


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Radiology

Lung Disease


Honeycombing


Tree-in-bud pattern

Consolidation Ground-glass opacity

Emphysema

Lung cysts Mosaic perfusion and

air trapping

Mosaic perfusion: Diagnosis


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Radiology

Mosaic perfusion: Diagnosis

Heterogeneous lung attenuation resulting fromregional differences in lung perfusion

Small airways disease or vascular obstruction

Patchy areas of varying lung attenuation

Relatively small vessels in regions of lowattenuation

Airway abnormalities in regions of lowattenuation


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Mosaic Perfusion: Significance


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Radiology

Mosaic Perfusion: Significance

Small airways disease or vascular obstruction Cystic fibrosis, bronchiectasis

Bronchiolitis obliterans, hypersensitivity

pneumonitis Chronic PE

May be the only HRCT finding

Expiratory scans or PFTs helpful in diagnosis Differentiate from ground-glass opacity

Swyer James


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Obliterative Bronchiolitis


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Obliterative Bronchiolitis


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Radiology

TEST CASES


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Lymphangitic

carcinomatosis

Panlobular Emphysema


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Idiopathic Pulmonary Fibrosis


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Radiology


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INHALATIONAL PNEUMOCONIOSIS

PARENCHYMAL HEMORRHAGE


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Radiology

Remote Varicella


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Radiology



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Radiology


Haemophilus influenzae


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Radiology

Emphysema


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Emphysema

LCH Post Lung Transplant


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Radiology

C Post u g a sp a t

BRONCHIECTASIS (CF)


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( )

COP


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Severe Emphysema


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SUMMARY


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Radiology

Look at overall predominant pattern of disease Reticular, fibrotic, nodular,

Tree-in-bud, consolidation, GGO

Emphysema, lung cysts, mosaic perfusion

Consider history and accompanying test results

Suggest DDx based on top 3 on the

differential diagnosis list


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THANK-YOU!

High Resolution Lung Ct

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