A 58-year-old woman with acute dyspnea and chest pain undergoes CT pulmonary angiography (CTPA). The radiologist identifies a filling defect in the right lower lobe pulmonary artery. Regarding the imaging findings and criteria for PE diagnosis on CTPA, all of the following are true EXCEPT:

Question

Accepted Answer

C. Peripheral wedge-shaped opacities (Hampton's hump) on CTPA indicate pulmonary infarction and are highly specific for PE. ## Understanding CTPA Diagnostic Criteria and Signs

### Primary Diagnostic Criteria

**Key Point:** Central, lobar, or segmental pulmonary artery filling defects are diagnostic of acute PE on CTPA. Subsegmental defects require clinical correlation and may be over-diagnosed.

### Direct Signs of PE on CTPA

| Sign | Description | Significance |
|------|-------------|---------------|
| **Central/Lobar/Segmental filling defect** | Thrombus completely or partially obstructing vessel lumen | Diagnostic of PE |
| **Polo mint sign** | Thrombus with central lucency surrounded by contrast | Indicates partial recanalization or chronic PE |
| **Saddle embolus** | Thrombus straddling pulmonary artery bifurcation | Indicates massive PE |
| **Trailing edge sign** | Contrast flowing around thrombus | Confirms acute PE |

### Secondary Signs of PE

**High-Yield:** Secondary signs are supportive but NOT diagnostic on their own:
- **Mosaic perfusion**: Areas of hypoperfusion (dark) alternating with normal perfusion (bright), reflecting regional blood flow obstruction
- **Wedge-shaped peripheral opacities (Hampton's hump)**: Indicates pulmonary infarction, which occurs in only 10% of PE cases and is NOT specific to PE (can occur with pneumonia, aspiration, etc.)
- **Right heart strain**: RV dilatation, interventricular septal bowing, reflux of contrast into IVC/hepatic veins

### Why Option 3 Is Incorrect

**Warning:** Hampton's hump (wedge-shaped consolidation) is a **secondary sign** of PE, not a primary diagnostic criterion. It indicates pulmonary infarction, which is:
- Present in only ~10% of PE cases
- NOT specific for PE (seen in pneumonia, aspiration, vasculitis)
- A consequence of dual blood supply failure (pulmonary + bronchial circulation)

While it may support PE diagnosis in the right clinical context, it is neither required nor highly specific for PE diagnosis.

**Clinical Pearl:** The absence of Hampton's hump does not exclude PE. Most PE patients do not develop infarction because the bronchial circulation provides collateral perfusion.

[cite:Harrison 21e Ch 297]

Answer

A. The 'polo mint' sign represents a thrombus with a central lucency surrounded by contrast, indicating partial recanalization

Answer

B. A central or segmental filling defect is sufficient for PE diagnosis without need for subsegmental confirmation

Answer

D. Mosaic perfusion pattern on CTPA reflects areas of hypoperfusion distal to emboli and is a secondary sign of PE

A 58-year-old woman with acute dyspnea and chest pain undergoes CT pulmonary angiography (CTPA). The radiologist identifies a filling defect in the right lower lobe pulmonary artery. Regarding the imaging findings and criteria for PE diagnosis on CTPA, all of the following are true EXCEPT:

Explanation

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