Radiology Features

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Diagnosing IPF:Radiologic features of IPF

All patients with suspected IPF should undergo HRCT evaluation

HRCT allows a detailed examination of the lung parenchyma2

HRCT, high-resolution computed tomography

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.

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

  • Non-contrast
  • Thin collimation (≤2 cm)
  • Prone scans
  • Expiratory scans
1. Raghu G et al. Am J Respir Crit Care Med. 2011; 183(6):788-824.

There are 3 types of UIP pattern based on HRCT findings

The 2011 ATS/ERS/JRS/ALAT guidelines define3 categories of UIP based on the presence or absence of specific HRCT features1
–Definite UIP pattern
–Possible UIP pattern
–Inconsistent with UIP pattern

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 IPF3

1. Raghu G et al. Am J Respir Crit Care Med. 2011; 183(6):788-824.
3. Larsen BT et al. Arch Pathol Lab Med. 2012;136(10):1234-1241.

HRCT in IPF

The distribution and predominance of specific features on HRCT scans are key factors in determining UIP patterns4
 
4. Schmidt SL et al. Respirology. 2009;14(7):934-939.

Definite UIP: Criteria

The features necessary for a definite UIP diagnosis are1:

Subpleural, basal predominance
AND
Reticular abnormality
AND
Honeycombing with or without traction bronchiectasis
AND
Absence of features listed as inconsistent with UIP pattern (see Not UIP section)

HRCT criteria for usual interstitial pneumonia. Reprinted with permission of the American Thoracic Society. Copyright ©2014 American Thoracic Society. Raghu G, Collard HR, Egan JJ, et al. An official ATS/ERS/JRS/ALAT statement: idiopathic pulmonary fibrosis: evidence-based guidelines for diagnosis and management. Am J Respir Crit Care Med. 2011;183(6):788-824. Official Journal of the American Thoracic Society. Note: this document was published in 2011 and is currently in revision. Certain aspects of this document may be out of date and caution should be used when applying these in clinical practice or other usages.

1. Raghu G et al. Am J Respir Crit Care Med. 2011; 183(6):788-824.

Definite UIP: Example

Definite UIP shows1,2:
–Subpleural basilar reticular changes
–Honeycombing
–Traction bronchiectasis
–No additional HRCT features considered inconsistent with UIP 

The distribution of UIP is characteristically basal and peripheral, though often patchy1,4

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

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

Definite UIP

Honeycombing is critical for diagnosing cases of definite UIP without surgical biopsy1,4,5

1. Raghu G et al. Am J Respir Crit Care Med. 2011; 183(6):788-824.
4. Schmidt SL et al. Respirology. 2009;14(7):934-939.
5. Hunninghake GW et al. Chest 2003;124(4):1215-1223.

Definite UIP (cont.)

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

1. Raghu G et al. Am J Respir Crit Care Med. 2011; 183(6):788-824.

Possible UIP: Criteria

Criteria for a diagnosis of possible UIP1:

Subpleural, basal predominance
AND
Reticular abnormality
AND
Absence of features listed as inconsistent with UIP pattern (see Not UIP section)

HRCT criteria for usual interstitial pneumonia. Reprinted with permission of the American Thoracic Society. Copyright ©2014 American Thoracic Society. Raghu G, Collard HR, Egan JJ, et al. An official ATS/ERS/JRS/ALAT statement: idiopathic pulmonary fibrosis: evidence-based guidelines for diagnosis and management. Am J Respir Crit Care Med. 2011;183(6):788-824. Official Journal of the American Thoracic Society. Note: this document was published in 2011 and is currently in revision. Certain aspects of this document may be out of date and caution should be used when applying these in clinical practice or other usages.

1. Raghu G et al. Am J Respir Crit Care Med. 2011; 183(6):788-824.

Possible UIP: Example

The absence of honeycombing in possible UIP means that a surgical lung biopsy is needed to make a definite diagnosis of IPF1,2

Note the lack of honeycombing and traction bronchiectasis in this image

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.

1. Raghu G et al. Am J Respir Crit Care Med. 2011; 183(6):788-824.
2. Meltzer et al. Orphanet J Rare Dis2008;3:1-15.

Surgical lung biopsy is not always possible

A surgical biopsy may be deferred due to underlying comorbidities, poor pulmonary function, or patient preference1
 
1. Raghu G et al. Am J Respir Crit Care Med. 2011; 183(6):788-824.

Inconsistent with UIP pattern

The presence of any of these features should lead to the consideration of an alternative diagnosis1

Upper- or mid-lung predominance
Peribronchovascular predominance
Extensive ground-glass abnormality (extent > reticular abnormality)
Profuse micronodules (bilateral, predominantly upper lobes)
Discrete cysts (multiple, bilateral, away from areas of honeycombing)
Diffuse mosaic attenuation/air trapping (bilateral, in 3 or more lobes)
Consolidation in bronchopulmonary segment(s)/lobe(s)

HRCT criteria for usual interstitial pneumonia. Reprinted with permission of the American Thoracic Society. Copyright ©2014 American Thoracic Society. Raghu G, Collard HR, Egan JJ, et al. An official ATS/ERS/JRS/ALAT statement: idiopathic pulmonary fibrosis: evidence-based guidelines for diagnosis and management. Am J Respir Crit Care Med. 2011;183(6):788-824. Official Journal of the American Thoracic Society. Note: this document was published in 2011 and is currently in revision. Certain aspects of this document may be out of date and caution should be used when applying these in clinical practice or other usages.

1. Raghu G et al. Am J Respir Crit Care Med. 2011; 183(6):788-824.

Upper-lung predominance

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

Peribronchovascular predominance

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

Extensive ground-glass abnormalities

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

Profuse perilymphatic micronodules

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

Discrete cysts

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

Diffuse mosaic attenuation/air trapping

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

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

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 possible UIP or inconsistent with UIP pattern should undergo additional diagnostic evaluation1
 
1. Raghu G et al. Am J Respir Crit Care Med. 2011; 183(6):788-824.

Summary

  • All patients with suspected IPF should undergo HRCT evaluation1,2
  • There are three types of UIP pattern on HRCT1
    • Definite UIP, Possible UIP, Inconsistent with UIP
  • A definite UIP pattern on HRCT in cases of suspected IPF confirms a diagnosis without the need for biopsy1
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.

References

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.Larsen BT et al. Arch Pathol Lab Med. 2012;136(10):1234-1241.
4.Schmidt SL et al. Respirology. 2009;14(7):934-939.
5.Hunninghake GW et al. Chest 2003;124(4):1215-1223.