MCQ Mosaic Attenuation Pattern

Question 1

What does mosaic attenuation represent on HRCT?
A. Alternating regions of lung consolidation and atelectasis
B. A patchwork pattern of differing lung attenuation
C. Uniform interstitial thickening throughout the lung
D. Large cavitary lesions in both lungs

Correct Answer: B. A patchwork pattern of differing lung attenuation
Explanation: “Mosaic attenuation refers to a radiologic pattern observed on HRCT of the chest, characterized by regions of differing lung attenuation forming a patchwork appearance.”
References:

Question 2

Which condition is most commonly associated with air trapping and mosaic attenuation on expiratory imaging?
A. Chronic thromboembolic pulmonary hypertension (CTEPH)
B. Hypersensitivity pneumonitis
C. Bronchiolitis obliterans
D. Pulmonary edema

Correct Answer: C. Bronchiolitis obliterans
Explanation: “Mosaic attenuation with persistent low-attenuation regions on expiratory imaging is a hallmark of air trapping, often seen in small airway diseases such as bronchiolitis obliterans.”
References:

  • Radiopaedia: Air Trapping and Small Airway Disease

  • Question 3

    What is the significance of the head cheese sign in mosaic attenuation?
    A. It indicates a combination of vascular and airway diseases.
    B. It represents areas of ground-glass opacity, consolidation, and normal lung.
    C. It confirms the diagnosis of chronic thromboembolic pulmonary hypertension.
    D. It is pathognomonic for hypersensitivity pneumonitis.

    Correct Answer: B. It represents areas of ground-glass opacity, consolidation, and normal lung.
    Explanation: “The head cheese sign on HRCT refers to the combination of ground-glass opacity, areas of consolidation, and regions of normal lung, commonly seen in hypersensitivity pneumonitis.”
    References:

    Question 4

    How does CHF contribute to mosaic attenuation?
    A. By causing regional air trapping
    B. By creating patchy hypoperfusion and vascular engorgement
    C. By leading to traction bronchiectasis
    D. By producing diffuse interstitial thickening

    Correct Answer: B. By creating patchy hypoperfusion and vascular engorgement
    Explanation: “CHF can cause mosaic attenuation through vascular redistribution, with areas of increased attenuation due to vascular engorgement and decreased attenuation from hypoperfusion.”
    References:

    Question 5

    What is the primary distinguishing feature between small airway disease and vascular causes of mosaic attenuation on HRCT?
    A. Presence of ground-glass opacities
    B. Disappearance of mosaic pattern on expiratory imaging
    C. Presence of air bronchograms
    D. Resolution of low attenuation areas with diuretics

    Correct Answer: B. Disappearance of mosaic pattern on expiratory imaging
    Explanation: “In small airway disease, air trapping persists on expiratory imaging, while in vascular causes, the mosaic attenuation pattern resolves during expiration.”
    References:

    Question 6

    Which imaging finding suggests small airway disease as the cause of mosaic attenuation?
    A. Mosaic attenuation disappears on expiration.
    B. High-attenuation regions show vascular redistribution.
    C. Persistent air trapping in low-attenuation areas on expiratory imaging.
    D. Diffuse consolidation with ground-glass opacities.

    Correct Answer: C. Persistent air trapping in low-attenuation areas on expiratory imaging.
    Explanation: “Persistent air trapping in low-attenuation areas during expiratory imaging is a key feature of small airway diseases.”
    References:

    Question 7

    What pulmonary function test result is most consistent with small airway disease presenting with mosaic attenuation?
    A. Restrictive pattern with reduced total lung capacity
    B. Obstructive pattern with reduced FEV1/FVC ratio
    C. Normal PFTs with isolated DLCO reduction
    D. Mixed obstructive and restrictive pattern

    Correct Answer: B. Obstructive pattern with reduced FEV1/FVC ratio
    Explanation: “Small airway diseases are typically associated with an obstructive pattern on PFTs, including a reduced FEV1/FVC ratio.”
    References:

    Question 8

    Which clinical feature is most likely associated with mosaic attenuation in hypersensitivity pneumonitis?
    A. Chronic cough with intermittent hemoptysis
    B. Acute dyspnea following chemical exposure
    C. Chronic dyspnea with a history of exposure to organic dust
    D. Sudden-onset pleuritic chest pain

    Correct Answer: C. Chronic dyspnea with a history of exposure to organic dust
    Explanation: “Hypersensitivity pneumonitis is characterized by chronic dyspnea and a history of organic dust exposure, often correlating with mosaic attenuation on HRCT.”
    References:

    Question 9

    What additional imaging modality can help confirm vascular causes of mosaic attenuation?
    A. Doppler ultrasound
    B. Ventilation-perfusion (V/Q) scan
    C. Chest X-ray
    D. Positron emission tomography (PET)

    Correct Answer: B. Ventilation-perfusion (V/Q) scan
    Explanation: “A V/Q scan can demonstrate patchy perfusion defects, supporting the diagnosis of pulmonary vascular disease as the cause of mosaic attenuation.”
    References:

    Question 10

    Which of the following is a characteristic HRCT finding in mosaic attenuation due to chronic thromboembolic pulmonary hypertension (CTEPH)?
    A. Traction bronchiectasis
    B. Air trapping in non-dependent regions
    C. Enlarged pulmonary arteries with patchy hypoperfusion
    D. Thickened interlobular septa

    Correct Answer: C. Enlarged pulmonary arteries with patchy hypoperfusion
    Explanation: “In CTEPH, HRCT often reveals enlarged pulmonary arteries and regions of patchy hypoperfusion, contributing to mosaic attenuation.”
    References:

  • Question 11

    Under which condition is mosaic attenuation considered a normal finding on expiratory imaging?
    A. When it is widespread across the lungs
    B. When it is confined to dependent lung regions and limited in extent
    C. When it is associated with ground-glass opacities
    D. When it is accompanied by interlobular septal thickening

    Correct Answer: B. When it is confined to dependent lung regions and limited in extent
    Explanation: “Limited mosaic attenuation confined to dependent lung regions on expiratory imaging can be a normal finding due to gravitational effects and minor perfusion differences.”
    References: