Questions
- Which of the following is the most common cause of mosaic attenuation?
- A) Hypersensitivity pneumonitis
- B) Chronic obstructive pulmonary disease (COPD)
- C) Pulmonary embolism
- D) Obliterative bronchiolitis
Answer: B) Chronic obstructive pulmonary disease (COPD)
Comment (Correct Answer): COPD is the most frequent cause of mosaic attenuation due to its common presentation of small airway disease and regional air trapping.
“Mosaic attenuation on CT is often observed in obstructive airway diseases such as COPD, reflecting heterogeneous lung perfusion and ventilation patterns.” (Radiopaedia)Incorrect Answers:
- A) Hypersensitivity pneumonitis
“Hypersensitivity pneumonitis typically presents with a head cheese sign, which involves mixed patterns including ground-glass opacity and air trapping, but it is not the most common cause of mosaic attenuation.” (Fleischner Society Glossary) - C) Pulmonary embolism
“Pulmonary embolism causes mosaic attenuation secondary to vascular perfusion mismatches, which are less common than airway-related causes like COPD.” (Radiopaedia) - D) Obliterative bronchiolitis
“Obliterative bronchiolitis causes air trapping but is less prevalent compared to COPD.” (Radiology Key)
- Which of the following imaging techniques is most effective in distinguishing air trapping as a cause of mosaic attenuation?
- A) Inspiratory CT
- B) Expiratory CT
- C) Chest X-ray
- D) PET-CT
Answer: B) Expiratory CT
Comment (Correct Answer): Expiratory CT emphasizes areas of air trapping by revealing regions that remain hypodense during expiration.
“Expiratory CT is pivotal in identifying air trapping, as affected regions fail to show the normal increase in attenuation seen during expiration.” (Radiology Key)Incorrect Answers:
- A) Inspiratory CT
“Inspiratory CT can visualize mosaic attenuation but does not differentiate air trapping effectively.” (Radiographics) - C) Chest X-ray
“Chest X-ray lacks the sensitivity to detect small airway pathology and air trapping.” (AJR) - D) PET-CT
“PET-CT is used for oncologic and metabolic imaging and is not the modality of choice for assessing air trapping.” (Radiopaedia)
- True or False: The head cheese sign is exclusively associated with interstitial lung diseases.
- A) True
- B) False
Answer: B) False
Comment (Correct Answer): The head cheese sign is not exclusive to interstitial lung diseases; it is commonly associated with hypersensitivity pneumonitis, involving a combination of normal lung, ground-glass opacity, and air trapping.
“The head cheese sign represents a mix of normal lung, ground-glass opacities, and air trapping, frequently noted in hypersensitivity pneumonitis.” (Fleischner Society Glossary)Incorrect Answer:
- A) True
“Interstitial lung diseases may present with a head cheese sign but are not the sole conditions associated with this pattern.” (Radiology Key)
- Which of the following diseases is most likely to present with unilateral mosaic attenuation?
- A) Hypersensitivity pneumonitis
- B) Swyer-James syndrome
- C) COPD
- D) Interstitial lung disease
Answer: B) Swyer-James syndrome
Comment (Correct Answer): Swyer-James syndrome results from post-infectious obliterative bronchiolitis, leading to unilateral mosaic attenuation with air trapping and lung volume loss.
“Unilateral air trapping with associated lung volume loss is a hallmark of Swyer-James syndrome.” (Radiopaedia)Incorrect Answers:
- A) Hypersensitivity pneumonitis
“Hypersensitivity pneumonitis typically results in bilateral, diffuse patterns of mosaic attenuation rather than unilateral.” (Fleischner Society Glossary) - C) COPD
“COPD typically causes bilateral mosaic attenuation due to its diffuse airway involvement.” (AJR) - D) Interstitial lung disease
“Interstitial lung disease results in patchy, often bilateral, areas of attenuation rather than unilateral air trapping.” (Radiology Key)
- Which modality is most sensitive for detecting small airway disease as a cause of mosaic attenuation?
- A) Expiratory CT
- B) Inspiratory CT
- C) VQ Scan
- D) Chest X-ray
Answer: A) Expiratory CT
Comment (Correct Answer): Expiratory CT is the gold standard for identifying small airway disease as it highlights regions of air trapping during exhalation.
“Expiratory CT provides critical diagnostic insight into air trapping, revealing hypodense areas caused by small airway obstruction.” (Radiopaedia)Incorrect Answers:
- B) Inspiratory CT
“Inspiratory CT provides an overview of lung parenchyma but does not differentiate air trapping effectively.” (Radiographics) - C) VQ Scan
“While VQ scans detect perfusion abnormalities, they lack sensitivity for detecting small airway disease directly.” (Radiopaedia) - D) Chest X-ray
“Chest X-ray is insufficient for detecting mosaic attenuation or small airway disease.” (AJR)
Questions
- What is the primary distinguishing feature of mosaic attenuation caused by vascular abnormalities compared to small airway diseases?
- A) Regional air trapping on expiratory CT
- B) Perfusion defects on VQ scan
- C) Presence of ground-glass opacities
- D) Uniform attenuation on inspiratory CT
Answer: B) Perfusion defects on VQ scan
Comment (Correct Answer): Vascular abnormalities cause perfusion defects that can be identified on VQ scans, differentiating them from airway-related causes of mosaic attenuation.
“Mosaic attenuation caused by vascular disease is characterized by regional perfusion defects, often detectable on VQ scans.” (Radiopaedia)Incorrect Answers:
- A) Regional air trapping on expiratory CT
“Air trapping on expiratory CT is indicative of small airway disease, not vascular abnormalities.” (Radiology Key) - C) Presence of ground-glass opacities
“Ground-glass opacities are commonly associated with interstitial lung diseases, not vascular or small airway pathology.” (Fleischner Society Glossary) - D) Uniform attenuation on inspiratory CT
“Uniform attenuation does not differentiate between vascular or airway-related causes of mosaic attenuation.” (AJR)
- Which of the following is NOT a common associated finding in mosaic attenuation caused by small airway disease?
- A) Bronchial wall thickening
- B) Air trapping on expiratory CT
- C) Subpleural sparing
- D) Mucus plugging
Answer: C) Subpleural sparing
Comment (Correct Answer): Subpleural sparing is typically seen in interstitial lung diseases, not small airway diseases.
“Subpleural sparing is a feature associated with interstitial lung diseases, particularly nonspecific interstitial pneumonia.” (Radiopaedia)Incorrect Answers:
- A) Bronchial wall thickening
“Bronchial wall thickening is a hallmark of small airway diseases, often noted in COPD and bronchiolitis.” (Radiology Key) - B) Air trapping on expiratory CT
“Air trapping is a defining feature of small airway disease as observed on expiratory CT.” (Radiopaedia) - D) Mucus plugging
“Mucus plugging can exacerbate airway obstruction and is frequently seen in small airway diseases.” (AJR)
- True or False: Mosaic attenuation always indicates a pathological process.
- A) True
- B) False
Answer: B) False
Comment (Correct Answer): Mosaic attenuation can occur as a normal variant, particularly in cases of poor inspiratory effort during imaging.
“Mosaic attenuation may occasionally be observed as a normal variant in studies with suboptimal inspiratory effort.” (Radiopaedia)Incorrect Answer:
- A) True
“While mosaic attenuation is frequently pathological, it can also appear in normal lungs under specific imaging conditions.” (Radiology Key)
- Which pattern of mosaic attenuation is most typical in hypersensitivity pneumonitis?
- A) Unilateral mosaic attenuation
- B) Bilateral diffuse mosaic attenuation with air trapping
- C) Upper lobe predominant mosaic attenuation
- D) Mosaic attenuation without air trapping
Answer: B) Bilateral diffuse mosaic attenuation with air trapping
Comment (Correct Answer): Hypersensitivity pneumonitis frequently presents with bilateral, diffuse patterns of mosaic attenuation accompanied by air trapping.
“Bilateral mosaic attenuation with air trapping is a characteristic finding in hypersensitivity pneumonitis.” (Fleischner Society Glossary)Incorrect Answers:
- A) Unilateral mosaic attenuation
“Unilateral mosaic attenuation is more commonly associated with Swyer-James syndrome or localized airway diseases.” (Radiopaedia) - C) Upper lobe predominant mosaic attenuation
“Upper lobe predominance may occur in certain interstitial lung diseases but is not a defining feature of hypersensitivity pneumonitis.” (AJR) - D) Mosaic attenuation without air trapping
“Air trapping is a hallmark of hypersensitivity pneumonitis and differentiates it from vascular or interstitial causes.” (Radiology Key)
- Which of the following conditions would most likely produce mosaic attenuation without air trapping?
- A) Pulmonary embolism
- B) Hypersensitivity pneumonitis
- C) COPD
- D) Swyer-James syndrome
Answer: A) Pulmonary embolism
Comment (Correct Answer): Pulmonary embolism typically causes mosaic attenuation due to regional perfusion abnormalities rather than air trapping.
“Vascular causes of mosaic attenuation, such as pulmonary embolism, result from perfusion defects without significant air trapping.” (Radiopaedia)
Incorrect Answers:
- B) Hypersensitivity pneumonitis
“Hypersensitivity pneumonitis involves both air trapping and ground-glass opacities in affected regions.” (Fleischner Society Glossary) - C) COPD
“COPD is characterized by diffuse air trapping, contributing to mosaic attenuation.” (Radiopaedia) - D) Swyer-James syndrome
“Swyer-James syndrome is marked by unilateral air trapping and volume loss, distinguishing it from vascular causes.” (Radiology Key)