Radiology Features

Diagnosing IPF:Radiologic features of IPF

All patients with suspected IPF should undergo HRCT evaluation1-3

HRCT allows a detailed examination of the lung parenchyma2

1. Raghu G et al. Am J Respir Crit Care Med. 2011;183(6):788-824. 2. Meltzer EB et al. Orphanet J Rare Dis. 2008;3:1-15. 3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68.

HRCT, high-resolution computed tomography

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3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68.

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An HRCT for evaluating ILD should follow  guidelines for improving diagnostic results3

• Non-contrast
• Thin collimation (≤2 cm), short rotation time, highest pitch for motion-free scan
• Number of acquisitions in proper position (3):

1.Supine, sustained end-inspiration
2.Supine, entire thorax at sustained end-expiration after prolonged expiration (volumetric or sequential acquisition)
3.Volumetric or sequential image (can be limited to lower lobes) to clear position-induced changes

• Scan for new ground-glass changes, acute pulmonary embolism via CT angiography with/without noncontrast HRCT

3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68. 4. Larsen BT et al. Arch Pathol Lab Med. 2012;136(10):1234-1241.

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There are 4 categories of UIP pattern based on HRCT findings
The 2018 ATS/ERS/JRS/ALAT guidelines define4 categories for diagnosing UIP based on the presence or absence of specific HRCT features3
–UIP pattern
–Probable UIP pattern
–Indeterminate UIP pattern
–Alternative diagnosis
 
The HRCT criteria were devised to convey a level of confidence for a radiologic diagnosis of UIP in a patient with clinical features that suggest a diagnosis of IPF4

HRCT in IPF

The distribution and predominance of specific features on HRCT scans are key factors in determining UIP patterns5

 

5. Schmidt SL et al. Respirology. 2009;14(7):934-939.

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3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68. 6. Lynch DA et al. Lancet. 2018;6(2):138-153.

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UIP: Criteria
The features necessary for a UIP diagnosis are3,6:
Subpleural and basal predominance (distribution is often heterogeneous)
Honeycombing with or without peripheraltraction bronchiectasis/bronchiolectasis
AND
HRCT criteria for usual interstitial pneumonia. Copyright ©2018 American Thoracic Society. Raghu G et al. Diagnosis of Idiopathic Pulmonary Fibrosis: An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline. Am J Respir Crit Care Med. 2018;198(5):e44-e68. Official Journal of the American Thoracic Society. Note: this document was published in 2018.

CHANGE_ME

UIP: Example
1. Raghu G et al. Am J Respir Crit Care Med. 2011;183(6):788-824. 3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68. 5. Schmidt SL et al. Respirology. 2009;14(7):934-939. 6. Lynch DA et al. Lancet. 2018;6(2):138-153.
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The distribution of UIP is characteristically basal and peripheral, though often patchy1,3,5,6
Image courtesy of and used with permission from Robert Suh, MD.

UIP

Honeycombing is critical for an HRCT diagnosis of UIP without surgical biopsy1,3,5-7

1. Raghu G et al. Am J Respir Crit Care Med. 2011;183(6):788-824. 3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68. 5. Schmidt SL et al. Respirology. 2009;14(7):934-939. 6. Lynch DA et al. Lancet. 2018;6(2):138-153. 7. Hunninghake GW et al. Chest 2003;124(4):1215-1223.

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UIP (cont.)

In cases of UIP, ground-glass opacities may be present but should be less extensive than the reticulation1,3,6

 

Mediastinal lymphadenopathy may be present3

1. Raghu G et al. Am J Respir Crit Care Med. 2011;183(6):788-824. 3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68. 6. Lynch DA et al. Lancet. 2018;6(2):138-153.

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3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68. 6. Lynch DA et al. Lancet. 2018;6(2):138-153.

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Probable UIP: Criteria
Criteria for a diagnosis of probable UIP3,6:
May have mild ground-glass opacities
Subpleural and basal predominance (often heterogenous distribution)
AND
Reticular pattern with peripheraltraction bronchiectasis/bronchiolectasis
AND
HRCT criteria for usual interstitial pneumonia. Copyright ©2018 American Thoracic Society. Raghu G et al. Diagnosis of Idiopathic Pulmonary Fibrosis: An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline. Am J Respir Crit Care Med. 2018;198(5):e44-e68. Official Journal of the American Thoracic Society. Note: this document was published in 2018.

CHANGE_ME

Probable UIP: Example
HRCT image of possible usual interstitial pneumonia. Reprinted from Fishman's Pulmonary Diseases and Disorders, 4th edition 2007. Meltzer, EB and Noble, PW: Chapter 70, Idiopathic Pulmonary Fibrosis. Used with permission from McGraw-Hill Companies, Inc. Copyright © 2007 McGraw-Hill Companies, Inc.
2. Meltzer EB et al. Orphanet J Rare Dis2008;3:1-15. 3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68. 
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Note the lack of honeycombing in this image

Surgical lung biopsy is not always possible

A surgical biopsy may be deferred due to underlying comorbidities, poor pulmonary function, or patient preference1,3

 

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1. Raghu G et al. Am J Respir Crit Care Med. 2011;183(6):788-824. 3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68.

3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68. 6. Lynch DA et al. Lancet. 2018;6(2):138-153.

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Indeterminate for UIP: Criteria
Criteria for a diagnosis of indeterminate for UIP3,6:
Distribution or features of fibrosis not consistent with specific etiology (“truly indeterminate”)
Subpleural and basal predominance
AND
Subtle reticulation, may have ground-glass opacity (mild) or distortion (“early UIP pattern”)
AND
HRCT criteria for usual interstitial pneumonia. Copyright ©2018 American Thoracic Society. Raghu G et al. Diagnosis of Idiopathic Pulmonary Fibrosis: An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline. Am J Respir Crit Care Med. 2018;198(5):e44-e68. Official Journal of the American Thoracic Society. Note: this document was published in 2018.

CHANGE_ME

Indeterminate for UIP: Example
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3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68. 6. Lynch DA et al. Lancet. 2018;6(2):138-153.
Image courtesy of and used with permission from Robert Suh, MD.
UIP pattern maybe found on histological testing of patients with HRCT patterns indeterminate for UIP6

Alternative diagnosis

The presence of any of these features should lead to the consideration of an alternative diagnosis3,6

 

Mosaic attenuation

Consolidation

Cysts, nodules (profuse or centrilobular)

Peribronchovascular

Predominant GGO

3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68. 6. Lynch DA et al. Lancet. 2018;6(2):138-153.

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CT Features

Predominant Distribution

Other

Perilymphatic

Upper or mid-lung

Pleural plaques (consider) asbestosis)

Dilated esophagus, pleural effusions, pleural thickening (consider CTD)

Distal clavicular erosions (consider RA)

Extensive lymph node enlargement

GGO, ground-glass opacities; HRCT criteria for usual interstitial pneumonia. Copyright ©2018 American Thoracic Society. Raghu G et al. Diagnosis of Idiopathic Pulmonary Fibrosis: An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline. Am J Respir Crit Care Med. 2018;198(5):e44-e68. Official Journal of the American Thoracic Society. Note: this document was published in 2018.

Upper-lung predominance

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Image courtesy of and used with permission from David A Lynch, MD

Peribronchovascular predominance

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Image courtesy of and used with permission from David A Lynch, MD

Extensive ground-glass abnormalities

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Image courtesy of and used with permission from David A Lynch, MD

Profuse perilymphatic micronodules

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Image courtesy of and used with permission from David A Lynch, MD

Discrete cysts

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Image courtesy of and used with permission from Robert Suh, MD.

Diffuse mosaic attenuation/air trapping

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Image courtesy of and used with permission from David A Lynch, MD

 

 

 

 

 

Consolidation in bronchopulmonary segment(s)/lobe(s)

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Image courtesy of and used with permission from David A Lynch, MD

HRCT is not always enough to diagnose IPF

Patients who are clinically suspected of having IPF with HRCT features of either probable UIP, indeterminate UIP, or alternative diagnosis should undergo additional diagnostic evaluation3

 

3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68. 

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Summary

All patients with suspected IPF should undergo HRCT evaluation1-3

There are four types of UIP patterns on HRCT3,6

A UIP pattern on HRCT in conjunction with clinical findings may confirm a diagnosis of IPF without the need for biopsy1,3

1. Raghu G et al. Am J Respir Crit Care Med. 2011;183(6):788-824. 2. Meltzer EB et al. Orphanet J Rare Dis. 2008;3:1-15. 3. Raghu G et al. Am J Respir Crit Care Med. 2018;198(5):e44-e68. 6. Lynch DA et al. Lancet. 2018;6(2):138-153.

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References

 

 

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