Radiology of Connective Tissue Disease associated Interstitial Lung

Disease

John Murchison

Why do HRCT?

• Superior to CXR and conventional CT at showing parenchymal abnormalities

• With MDCT all CT chests are effectively HRCT

Indications for HRCT

• Is lung disease present?

• What is the nature of the abnormality?

• Are changes acute or chronic?

• Follow up to assist management

• Selection of biopsy site

Indications for HRCT

• Is lung disease present?– Much more sensitive at assessing lung

parenchma than CXR• Superimposed structures

• ? Normal ? Abnormal

– PFT abnormalities and apparently normal CXR• Is further management required?

• Or no need eg emphysema

Indications for HRCT

• What is the nature of the abnormality?– Sometimes able to give a specific diagnosis

• Bronchiectasis, UIP, emphysema

– Narrows the differential diagnosis• Appropriate selection of further tests

Indications for HRCT• Are changes acute or chronic?

– Chronic eg fibrosis

– Acute ground glass

• Follow up to assist management– Has disease progressed / improved?

• Selection of biopsy site– Many diffuse lung diseases have a patchy distribution.

Select active disease

– Avoid end stage fibrosis

Scanning Variants

• Supine scan- standard• Prone scan • Expiratory scan

Scanning Variants

• Prone scan- – dependant changes

often seen particularly at lung bases

– If concern that may be obscuring early fibrosis or that changes may not be genuine do prone scan

prone

supine

Scanning Variants

• Prone scan- – dependant changes

often seen particularly at lung bases

– If concern that may be obscuring early fibrosis or that changes may not be genuine do prone scan

prone

supine

Scanning Variants

• Expiratory scan– Demonstrates air trapping

• If concern re obstructive lung disease eg PFTs

• Hyperlucency on HRCT– If particularly looking for

conditions where air trapping likely eg Bronchiolitis obliterans

• In normal patients HU increases uniformly on expiration

• If air trapping HU remains low

Inspiration

Expiration

Patterns of air space opacification

ground glassconsolidation

Ground Glass

ground glass attenuation Ground glass attenuation

may be correlate with a) evidence of interstitial

inflammation with airspace filling by macrophages

b)patchy fibrosis or c) a combination of above.

HRCT features of fibrosis, Intra-lobular and inter-lobular septal thickening, walled cysts representing honeycombing, may be associated traction bronchiectasis

Diseases of known causeor association

Idiopathic interstitial

pneumonias

Others

Connective tissue

diseases

Drug-induced diseases

Asbestosis

Pneumoconiosis

DPLDDPLD

IPF / CFAIPF / CFA UIP

NSIP

AIP

LIP

COP

RB-ILD DIP

Granulomatous diseases

Sarcoidosis

Hypersensitivity pneumonitis

Eosinophilic diseases

Rare diseases

CXR-UIPInitially ill-defined or ground-glass opacities, peripheral reticular opacities,

As disease progresses reticular pattern becomes coarser, most marked at bases, often volume loss, end stage diffuse honeycombing.

HRCT1) features of fibrosis, Intralobular septal thickening, walled cysts representing honeycombing, may be associated traction bronchiectasis2)ground glass attenuation common but usually less than reticular abnormalities. Ground glass attenuation may be correlate with a) evidence of interstitial inflammation with airspace filling by macrophages b)patchy fibrosis or c) a combination of above.

3)characteristically a peripheral basal distribution

Radiological differential diagnosis in ‘IPF’•An HRCT that predominantly shows bibasal honeycombing is virtually 100% specific for UIP.•The HRCT pattern of UIP found in IPF can be indistinguishable from that seen in asbestosis, collagen vascular disease or as a response to drugs. •Patients with chronic hypersensitivity pneumonitis or with end-stage sarcoidosis can uncommonly develop a CT pattern similar to UIP

IPF

Drugs

CTD

Asbestosis

SarcoidSarcoid

EAAEAA

UIPUIPNSIPNSIP

DIP DIP RBILDRBILD

COPCOP

CXR NSIP

bilateral pulmonary infiltrates. Lower lung zones more frequently involved.

HRCT NSIP•1) ground glass predominant finding in most cases and sole finding ~50%.

• 2) Irregular linear or reticular opacities seen about 50% cases. May be traction bronchiectasis.

•3) Honeycombing and consolidation relatively infrequent

•4) Bilateral symmetrical basal predominance

NSIP radiological differential diagnosis

• Depends on the predominant pattern exhibited.

• Experienced radiologist found it indistinguishable from– UIP 32%

– Hypersensitivity pneumonitis 20%

– Organising pneumonia 14%– Other diagnosis 12% Radiology 2000 vol 217

Extent and Distribution of disease UIP /NSIP

• Feature NSIP UIP p value• Disease extent (%) 37.1 +/- 22.7 44.0 +/- 23 .29

• Ground glass (%) 47.4 +/- 27.2 26.7+/- 22.5 <.005

• Coarseness score (max 15) 6.0 +/- 3.1 8.3+/- 2.9 .01

• Subpleural distribution (%) 60 71 .08

• Basal distribution (%) 62 70 .25

• Bronchocentric distribution 5 9 .29

53 patients

Macdonald et al Radiology 2001: 221

COP radiology

• Patchy non-segmental, unilateral or bilateral areas of air space consolidation.

• Often vary in site and configuration over time.

• May be irregular reticular opacities. Rarely a major feature.

• Small nodular opacities usually with other features but occasionally on their own

COP• HRCT findings• 1 Bilateral Air-space Consolidation 80%• 2 Ground glass opacities 60%• 3 Subpleural and/or peribronchovascular

distribution• 4 Bronchial wall thickening, dilatation in

abnormal areas• 5 Small nodular opacities often peribronchiolar

(30-50% of cases)• 6 May get irregular reticular opacities• 7 Combination of findings in 1 and 2

COP pre and post treatment

HRCT Rheumatoid Arthritis

• HRCT patterns– UIP/ NSIP

– COP

– Brochiolitis obliterans

– Necrobiotic nodules

– Pleural thickening/ effusions

Scleroderma.(PSS)

• High prevalence of pulmonary involvement

• HRCT patterns– Pulmonary arterial

hypertension( 50%)

– ILD ( 80%) usually NSIP

– Pleural thickening /effusion

– Oesophageal dilatation.

CXR and CT clues

• Joint abnormalities particularly AC and shoulder joints with Rheumatoid arthritis

• Dilated oesophagus suggest scleroderma or variant• Pulmonary artery enlargement out of proportion to

lung parenchymal changes may reflect vaculopathy especially scleoderma

• Soft tissue calcification –dermatomosytis or scleroderma

• Multiple compartments think RA

Radiology of Idiopathic ILD

• The lung has a limited number of patterns of response to injury and there is often a lack of correlation between aetiological insult and radiological appearance of the lung

• We need to recognise that in many cases there is not a clear cut match between the ‘clinical syndrome’ and the ‘radiological pattern’ of disease

• The latter may be more important in determining prognosis

• Patients are managed in a multi-disciplinary manner in order to reach a final clinical diagnosis

Drug treatment

• Gold usually diffuse alveolar infiltrates- can look like OP• Methotrexate-

– can produce sub-acute hypersensitivity- centilobular ground glass– Pneumonitis –more likely if pre-existing ild

• D-penacillamine- constrictive bronchiolitis• Non -steroidals – hypersensitivity• Salicylates OD pulmonary oedema• Opportunist infections• Increased risk lymphoma and lung cancer