000 Reticular Pattern Reticulation

  • The reticular pattern,
    • characterized by a network of linear opacities
    • reflects the presence of fibrotic changes in  connective tissue structures including
      • the interlobular septa
      • intralobular tissues
        • bronchovascular bundle
        • interalveolar septa
  • . The specific combination of involvement in these structures can provide additional clues to the underlying cause of the fibrotic lung disease.

The secondary pulmonary lobule is a functional unit of the lung that is typically defined by the structures supplied by a single small bronchiole. In fibrotic lung diseases with a reticular pattern on imaging, the involvement is often related to changes in specific structures within the secondary lobule. The primary structures affected include:

  • Interlobular Septa:
    • Involvement in Reticular Disease:
      • Fibrosis or scarring of the interlobular septa can lead to
      • thickening  which can be irregular and incomplete
      • increased opacity,
    • Peribronchovascular Interstitium
      • Fibrosis in the peribronchovascular interstitium can lead to a reticular pattern,
      • especially if it affects the connective tissue around small bronchioles.
  • Subpleural Connective Tissue:
    • Involvement in Reticular Disease: Fibrosis in the subpleural connective tissue
  • Intralobular Septa:
    • Involvement in Reticular Disease: Fibrosis of the intralobular septa can also contribute to the reticular pattern.

 

Reticulation
Reticulation results from thickening of the interlobular or intralobular septa and appears as several linear opacities that resemble a mesh or a net on HRCT scans.7 The presence of reticulation is indicative of interstitial lung disease.7 (Hansell DM, Bankier AA, MacMahon H, et al. Fleischner Society: glossary of terms for thoracic imaging. Radiology. 2008;246:697-722.)
Radiology Rounds

 

  • Subpleural reticulation
    •  typically in a peripheral subpleural distribution
    • located ≤1 cm from the pleura
      • normal aging
        • can be accompanied by subpleural cysts,
        • independent of smoking history
      • UIP
        •  bilateral basilar subpleural reticulation,
        • traction bronchiectasis,
        • architectural distortion and
        • honeycombing
  • UIP reticulation
    UIP 05
    reticulation subpleural
    Case courtesy of Royal Melbourne Hospital Respiratory, Radiopaedia.org

    UIP and Reticular Pattern
    70 year old male with UIP and CHF showing extensive dominantly bibasilar and peripheral reticulation

    CXR UIP and Reticular Pattern
    70 year old male with UIP showing extensive dominantly bibasilar and peripheral reticulation
    Ashley Davidoff MD TheCommonVein.net
    CT UIP and Reticular Pattern Thickened Interlobular Septa
    70 year old male with UIP showing extensive dominantly bibasilar and peripheral reticulation
    Ashley Davidoff MD TheCommonVein.net uip-004
    CT UIP and Reticular Pattern
    70 year old male with UIP showing extensive dominantly bibasilar and peripheral reticulation
    Ashley Davidoff MD TheCommonVein.net uip-003
    CT UIP and Reticular Pattern
    70 year old male with UIP showing extensive dominantly bibasilar and peripheral reticulation
    Ashley Davidoff MD TheCommonVein.net uip-002
    CT UIP and Reticular Pattern
    70 year old male with UIP showing extensive dominantly bibasilar and peripheral reticulation
    Ashley Davidoff MD TheCommonVein.net uip-005
    CT UIP and Reticular Pattern
    70 year old male with UIP showing extensive dominantly bibasilar and peripheral reticulation
    Ashley Davidoff MD TheCommonVein.net uip-006
    CT UIP and Reticular Pattern
    70 year old male with UIP showing extensive dominantly bibasilar and peripheral reticulation
    Ashley Davidoff MD TheCommonVein.net uip-007
    CT UIP and Reticular Pattern
    70 year old male with UIP showing extensive dominantly bibasilar and peripheral reticulation
    Ashley Davidoff MD TheCommonVein.net uip-008

     

    Reticular Changes Caused by Fibrosis of the Interlobular Septa

Combined Pulmonary Fibrosis and Emphysema

CT Shows Combined Mild to Moderate Emphysema and Basilar Peripheral Interstitial Lung Disease
Ashley DavidoffMD TheCommonVein.net combined pulmonary fibrosis and emphysema 002
CT Shows Combined Mild to Moderate Emphysema and Basilar Peripoheral Interstitial Lung Disease
Ashley DavidoffMD TheCommonVein.net combined pulmonary fibrosis and emphysema 000b
CT Shows Combined Mild to Moderate Emphysema and Basilar Peripoheral Interstitial Lung Disease
Ashley DavidoffMD TheCommonVein.net combined pulmonary fibrosis and emphysema 000c
CT Shows Combined Mild to Moderate Emphysema and Basilar Peripheral Interstitial Lung Disease
Ashley DavidoffMD TheCommonVein.net combined pulmonary fibrosis and emphysema 003
CT Shows Combined Mild to Moderate Emphysema and Basilar Peripheral Interstitial Lung Disease
Ashley DavidoffMD TheCommonVein.net combined pulmonary fibrosis and emphysema 004

  • Post COVID 19

  • Reticular fibrosis post COVID
    Ashley Davidoff MD TheCommonVein.net
  • Diffuse Reticular Lung Disease
    • PCP HIV
    • PCP Pneumonia
      46 year old female with HIV presents with dyspnea. CXR scan shows a diffuse reticular pattern with suggestion of upper lobe predominance
      Ashley Davidoff MD TheCommonVein.net 30755c
      PCP Pneumonia
      48 year old male with HIV presents with dyspnea. CT scan shows a reticular pattern within ground glass background, dominantly in the lower lobes, and affecting the right lower lobe more than the left
      Ashley Davidoff MD TheCommonVein.net 30755c

      Reticular Changes Post XRT 

    • Reticular Changes Post XRT 
      Ashley Davidoff MD
      TheCommonVein.net

      Reticular Changes Post XRT 
      Ashley Davidoff MD
      TheCommonVein.net