000 Mosaic Attenuation Pattern Introduction

  • Mosaic attenuation is an
    • imaging pattern
      • variable lung attenuation
      • results in a heterogeneous appearance of the parenchyma.
      • sometimes it is caused by air trapping
      • sometimes by perfusion abnormalities
      • sometimes normal

Nutshell Buzz

patchwork

differing pulmonary attenuation

Mosaic attenuation refers to a patchy or uneven pattern of lung attenuation seen on CT imaging. It appears as areas of increased lung density (hyperattenuation) adjacent to areas of decreased lung density (hypovascular or hypodense regions). This pattern can be caused by several different factors, such as:

  1. Small Airway Disease: Mosaic attenuation can be associated with diseases affecting the small airways, such as chronic obstructive pulmonary disease (COPD) or bronchiolitis obliterans.
  2. Air Trapping: In conditions like asthma or other obstructive lung diseases, air may be trapped in certain lung regions during exhalation, leading to areas of hyperinflation and hyperattenuation.
  3. Pulmonary Embolism: Blood clots in the pulmonary arteries can lead to mismatched lung perfusion and cause mosaic attenuation patterns.
  4. Pulmonary Edema: Fluid accumulation in the lungs due to heart failure or other causes can result in mosaic attenuation.
  5. Infection and Inflammation: Certain lung infections and inflammatory conditions can also contribute to mosaic attenuation.
58f lungs mosaic attenuation 009
Ashley Davidoff
TheCommonVein.net
Mosaic attenuation pattern. CT scan through lower lobes shows the indirect sign of constrictive obliterative bronchiolitis, in this case the sequel to a severe viral lower respiratory tract infection.
https://pubs.rsna.org/doi/full/10.1148/radiol.13120908
CHF with Mosaic attenuation Ashley Davidoff MD TheCommonVein.net
Small airway disease and mosaic attenuation
Ashley Davidoff MD TheCommonVein.net

Mosaic Attenuation Caused by Obstruction of Small Airways 

  • Air trapping  on the other hand
  • is an imaging and physiologic  term to
  • retained air in a part or parts of the lung
  • more easily identified during expiration
  • caused by
    • obstruction

Mosaic Attenuation of a Secondary Lobule

Centrilobular Nodule – Small Airway and Mosaic Attenuation
77F with long history of dyspnea and cough showing medium and small airway disease, centri-lobular nodules, para-septal nodules ground glass changes and mosaic attenuation Diagnosis includes Stage 3 sarcoidosis
Ashley Davidoff
TheCommonVein.net
Mosaic Attenuation on Expiration Imaging Small Airway Disease
77F with long history of dyspnea and cough showing medium and small airway disease, centri-lobular nodules, para-septal nodules ground glass changes and mosaic attenuation Diagnosis includes Stage 3 sarcoidosis
Ashley Davidoff TheCommonVein.net

Mosaic Attenuation -Due to Mucoid Impaction COPD 

Multifocal regions of mosaic attenuation in the right lower lobe  .  The bronchiole in the right lower lobe is thickened and there is associated  bronchiolectasis These findings are consistent with small airway disease in a  patient with COPD 
Ashley Davidoff TheCommonVein.net bronchioles 004
Multifocal regions of mosaic attenuation in the right lower lobe .  The bronchiole in the right lower lobe is thickened and there is associated  bronchiolectasis These findings are consistent with small airway disease in a  patient with COPD 
Ashley Davidoff TheCommonVein.net bronchioles 003
Mosaic attenuation with thickening of the walls of the small airways in the right lower lobe
 in a patient with COPD – Small Airways are obstructed and air is trapped 
Ashley Davidoff MD TheCommonVein.net bronchioles 002
Mosaic attenuation with thickening of the walls of the small airways in the right lower lobe
Small Airways are  filled with mucus in a patient with COPD – Note centrilobular impaction of mucus Small Airways are obstructed and air is trapped 
Ashley Davidoff TheCommonVein.net bronchioles 001

Mosaic Attenuation with Bronchiectasis

Segmental and Subsegmental Bronchiectasis with mucoid impaction and evidence of small airway disease with and areas of mosaic attenuation
Ashley Davidoff MD TheCommonVein.net bronchiectasis 006
Segmental and Subsegmental Bronchiectasis with extension of the disease process into the small airways characterised by centrilobular nodules d and mosaic attenuation
Ashley Davidoff MD TheCommonVein.net bronchiectasis 009
Mosaic Attenuation in CHF
50 year old female with diabetes, chronic renal failure with congestive heart failure.  CT in the coronal plane shows diffuse ground glass changes, peribronchial cuffing and mosaic attenuation
Ashley Davidoff MD TheCommonvein.net  50-005-CT
50 year old female with diabetes, chronic renal failure with congestive heart failure.  CT in the coronal plane shows diffuse ground glass changes, peribronchial cuffing and mosaic attenuation
Ashley Davidoff MD TheCommonvein.net  50-006-CT
Mosaic Attenuation in a patient with SLE thought to represent small vessel disease
Mosaic Attenuation in a patient with SLE thought to represent small vessel disease
Ashley Davidoff TheCommonVein.net
Mosaic Attenuation in a patient with SLE thought to represent small vessel disease
Ashley Davidoff TheCommonVein.net
Within the Right Middle Lobe – Air Trapping – Vasoconstriction of the Vessels
This series of images shows some subtle changes that reflect the local control of blood flow to a small segment of the right middle lobe.  Note that in image a, there is a small area of increased lucency (blacker) in the right lung just lateral to the vessels of the right hilum.  This region is highlighted in b.  Note also that in b, the rapid diminution of the size of the blood vessel to that subsegment when compared to the size change of the vessels in the image in c.  The lucent appearance of the lung suggests air trapping and the vasoconstriction reflects decreased perfusion – ie with decreased ventilation there is an associated consequent associated decrease in perfusion.
47170c01.800 bronchocentric inflammation lung bronchovascular bundle chest inflammation peribronchial halo air trapping mosaic perfusion ground glass changes alveolar change air bronchogram acute bronchovascular inflammation ddx allergic collagen vascular disease infection CTscan
Ashley Davidoff MD TheCommonVein.net
Small airway disease and mosaic attenuation
Ashley Davidoff MD TheCommonVein.net
Small airway disease and mosaic attenuation
Ashley Davidoff MD TheCommonVein.net
40 year old female with SLE and congestive-cardiomyopathy. Axial CT (top row) shows a focal nodule that was connected to a bronchiole. Bronchiectasis with mucoid impaction and ABPA were radiological considerations. T2 weighted MRI (bottom row) shows T2 brightness confirming the fluid or proteinaceous nature of the nodule likely from mucoid impaction. Note surrounding mosaic attenuation suggesting associated small airway obstruction.
Ashley Davidoff MD TheCommonVein.net 002-CT-mucoid-impaction

 

Examples

Radiographics

Radiopedia