CT Features of Cement Pulmonary Embolism
Cement pulmonary embolism appears on CT as multiple linear or branching radiopaque (hyperdense) densities confined within the pulmonary artery courses, most frequently involving the upper lobes of bilateral lungs.
Primary Imaging Characteristics
The typical CT findings of cement pulmonary embolism (CPE) include 1:
- Multiple linear or branching radiopaque densities within pulmonary arteries
- Hyperdense lesions that follow the anatomical course of pulmonary vessels
- Distribution pattern: Upper lobes of bilateral lungs are most frequently involved
- Solitary or multiple fine radiodense lines with occasional branching patterns 2
Anatomical Distribution
CPE predominantly occurs in 1:
- Subsegmental pulmonary arteries (most common location - 14/19 emboli in one series) 3
- Segmental arteries (less common)
- Lobar arteries (rare)
- Main pulmonary artery (rare)
The upper lung zones are preferentially affected, likely due to venous drainage patterns from the vertebral venous plexus through the azygos system.
Associated Venous Findings
When evaluating for CPE, also assess for cement emboli in 1:
- Azygos vein (found in 103/373 cases - strong predictor of pulmonary embolism)
- Inferior vena cava (found in 8/373 cases - strongest predictor with OR 42.7)
The presence of cement in these venous structures significantly increases CPE risk, as they represent the pathway from vertebral venous plexuses to pulmonary circulation.
Imaging Technique Considerations
Standard CT Protocol
- Unenhanced CT scans viewed at lung window settings allow confident identification of cement emboli 4
- Hyperdense cement emboli may be less conspicuous on CT angiography with high-flow contrast injection due to surrounding vascular enhancement 4
Advanced Imaging
Dual-energy CT (DECT) pulmonary angiography provides additional information 5, 3:
- Enhanced visualization of radiopaque cement material in pulmonary arteries
- Iodine mapping can identify corresponding parenchymal perfusion defects
- Material decomposition helps differentiate cement from contrast or calcification
- Note: Not all cement emboli cause perfusion defects (only 12/19 in one series) 3
Clinical Context and Incidence
The reported incidence of CPE varies based on detection method 6, 1, 2, 7:
- 26% when systematically assessed by post-procedural CT (VERTOS II data) 6
- 17.2% in recent large series 1
- 6.8% when detected by chest radiography alone 2
- 1.9% when only symptomatic cases considered 7
Critical point: The vast majority of cement pulmonary emboli are asymptomatic with no reactive pulmonary changes 6, 1. However, symptomatic cases can range from mild respiratory symptoms to severe respiratory distress, ARDS, and death 6, 8.
Risk Factors Associated with CPE
When interpreting CT findings, consider these procedural risk factors 1, 7:
- T9 vertebral level treatment (OR 4.2)
- Three or more treated vertebrae (OR 2.4)
- Thoracic location versus lumbar
- PVP versus PKP (vertebroplasty has higher risk than kyphoplasty)
- Surgery within 2 weeks of fracture versus delayed treatment
- Hypervascular primary tumors (hepatocellular carcinoma, thyroid cancer) 9
Practical Imaging Approach
Post-procedural chest imaging should be obtained to detect asymptomatic CPE, particularly when:
- Multiple levels treated
- Thoracic vertebrae involved
- Cement leakage into azygos vein or IVC noted on spinal imaging
Review spinal CT first for cement distribution and venous leakage patterns (prevertebral, paravertebral, epidural, IVC)
Chest CT technique: Use lung windows on unenhanced or low-contrast phases for optimal cement visualization
Look systematically for linear/branching hyperdensities following pulmonary artery distribution, starting in upper lobes
The key distinguishing feature from thromboembolic disease is the characteristic hyperdense, radiopaque appearance of cement material, which is unmistakable on CT imaging.