PE Protocol: Expert Guide to Managing Incidental Findings on CT Scans

PE Protocol: Expert Guide to Managing Incidental Findings on CT Scans

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Introduction

The implementation of proper pulmonary embolism (PE) protocols is a critical component of modern clinical practice. Pulmonary embolism remains a potentially life-threatening condition, occurring in approximately 5% of patients undergoing computed tomography (CT) scans. Despite major advances in imaging technology, incidental pulmonary embolism continues to be a frequent and clinically relevant finding, identified in approximately 1.1% of coronary CT scans and 3.6% of oncological CT scans. These unexpected detections present unique challenges, requiring clinicians to balance the urgency of intervention with individual patient factors and comorbidities.

The prevalence of incidentally detected PE varies substantially across patient populations. In unselected groups, prevalence is estimated to range from 1% to 4%. However, oncology patients represent a particularly high-risk population. In this group, studies report a frequency of 3.9% compared with 6.6% in non-oncologic patients, with PE often identified in the absence of clinical suspicion. Indeed, 54% of all PE events in oncology patients were unsuspected, compared with only 19% in non-oncology cohorts. These findings underscore the necessity of optimizing CT chest PE protocols, not only to improve detection rates but also to guide timely and effective management strategies in vulnerable patient populations.

The consequences of a missed or delayed PE diagnosis can be profound. Untreated pulmonary embolism is associated with mortality rates approaching 30%. In contrast, early detection followed by appropriate anticoagulation therapy reduces mortality to 2–10%. This striking difference emphasizes the importance of accurate imaging protocols, systematic interpretation, and prompt initiation of treatment once PE is identified.

Despite these improvements in detection, uncertainty remains regarding the optimal management of incidental PE. The clinical significance of subsegmental emboli, the duration of anticoagulation in asymptomatic patients, and the risk-benefit balance in oncology patients remain topics of active debate. Current guidelines provide broad recommendations, yet real-world management often requires individualized decision-making that incorporates cancer status, bleeding risk, comorbid conditions, and overall prognosis.

This review synthesizes the latest evidence on pulmonary embolism detection, with particular attention to CT protocol timing and image optimization. It also addresses evidence-based management strategies for incidental PE across diverse patient populations, including oncology and non-oncology groups. By integrating epidemiological data, guideline recommendations, and clinical outcomes, this guide aims to provide clinicians with a framework for improving PE detection and ensuring effective management, thereby reducing morbidity and mortality associated with this condition.

Keywords: pulmonary embolism, incidental findings, CT protocol, anticoagulation, oncology, clinical management

 

Understanding Incidental PE on CT Scans

Pulmonary embolism detection has evolved considerably with advanced imaging technology, enabling the discovery of clots that might otherwise remain undetected. The distinction between different types of PE findings has important clinical implications for patient management.

Definition of incidental, unreported, and suspected PE

Incidental pulmonary embolism (IPE) refers to PE discovered on computed tomography scans performed for indications other than suspected PE. This contrasts with suspected PE, which is diagnosed when imaging is specifically ordered to evaluate symptoms suggestive of embolism. A third category—unreported PE—represents emboli that were present on imaging but overlooked during initial interpretation.

The distinction between these categories carries clinical significance. Studies reveal that PE remains unsuspected (either incidental or unreported) in 54% of all PE events in oncologic patients, while this occurs in only 19% of non-oncologic patients. Additionally, more than 50% of unsuspected PE events go unreported during initial evaluation. This oversight occurs despite the fact that these findings often warrant treatment, as guidelines suggest nearly all patients with acute PE should receive intervention, even when discovered incidentally.

Common CT scan types where PE is found

Incidental PE manifests across various examination types, with prevalence rates differing substantially between patient populations. IPE occurs in approximately 2.6% of routine clinical practice examinations, though this figure varies based on scanning technology and patient characteristics.

Multiple studies have documented where these unexpected findings occur most frequently:

• Oncologic CT examinations: 3.6% prevalence rate
• Coronary CT angiography: 1.1% prevalence rate
• Acute pulmonary disease evaluation: Highest frequency of incidental findings
• Follow-up cancer staging: 2.7% prevalence versus 1.9% in initial staging
• Trauma assessment: Notably high 24% prevalence in one study

The frequency of discovery has increased over time with the introduction of multi-slice CT machines. Earlier studies using 4-row CT scanners reported an incidence of 2.6% in cancer patients, while pooled analyzes of studies using modern multi-slice technology showed a slightly higher rate of 3.6%. This difference becomes more notable when comparing general population scans, with frequencies rising from 1.8% with older technology to 3.3% with modern CT scanners.

What is PE protocol in radiology?

The PE protocol in radiology encompasses specialized techniques to optimize pulmonary artery visualization and embolism detection. CT pulmonary angiography (CTPA) serves as the current standard of care, providing accurate diagnosis with rapid turnaround time. This protocol offers additional advantages beyond embolism detection, including information on other potential causes of acute chest pain.

Standard PE protocol implementation typically involves:

1. Contrast administration: Approximately 60ml of iodinated intravenous contrast medium administered at a rate of 2ml/second, with effective delays of 12-25 seconds when using automatic bolus timing in the pulmonary trunk.
2. Technical parameters: Imaging typically acquired at 120 kVp, 150-300 mAs with 1mm slice thickness and pitch of 0.6-1.2. For non-PE-specific indications, timing differs with typical delays of 40-50 seconds.
3. Visualization techniques: Optimal window settings enhance detection—studies show that using wider window settings (width, 600 H; level, 100-150 H) improves identification of unsuspected PE compared to standard mediastinal settings (width, 400 H; level, 40 H).

CTPA demonstrates high diagnostic accuracy, with the PIOPED II trial showing sensitivity of 83% and specificity of 96%. When combined with clinical probability assessments, positive predictive values rise to 92-96%. Modern protocols can detect even submillimeter subsegmental emboli and provide parameters for estimating PE severity and risk-stratification.

Despite these advances, technical issues such as suboptimal pulmonary artery opacification, motion artifacts, and examination-related distractors may contribute to missed diagnoses. Consequently, radiologists must maintain vigilance when reviewing studies with high PE risk, even when performed for unrelated indications.

 

CT Indications with High Incidental PE Frequency

Certain clinical scenarios carry higher risk profiles for incidental pulmonary embolism (PE) detection, requiring heightened vigilance when interpreting imaging studies. Understanding these high-risk indications helps radiologists implement appropriate PE protocols and improves detection rates.

Follow-up staging in oncologic patients

Cancer patients represent a population with distinctly elevated PE risk profiles. Studies demonstrate that PE frequency in follow-up staging examinations (2.7%) exceeds that of initial staging examinations (1.9%). This observation highlights the importance of vigilant vessel evaluation during routine oncologic surveillance imaging.

Most cancer patients discovered to have PE possess advanced disease; approximately 77% present with stage IV and 15% with stage III disease at diagnosis. Moreover, the majority (79%) of patients with incidental PE are undergoing active treatment—68% receiving chemotherapy and 12% undergoing radiotherapy.

Although termed “incidental,” retrospective evaluation of medical records often reveals that many patients exhibited symptoms at the time of diagnosis. Studies show 53% of patients later found to have PE had experienced respiratory symptoms including shortness of breath, chest pain, or hemoptysis alone or in combination. Furthermore, clinical evidence of deep vein thrombosis (DVT) was present in 18% of cases.

The anatomical distribution of emboli in cancer patients deserves attention; 53% of incidental PE cases involve central pulmonary arteries, whereas 47% affect peripheral vessels. This pattern differs from what is typically seen in symptomatic presentations, emphasizing the need for thorough evaluation of both central and peripheral pulmonary vasculature during oncologic imaging.

Evaluation of acute pulmonary disease

Acute pulmonary disease evaluation represents another clinical scenario with high incidental PE detection rates. Among non-oncologic patients with acute pulmonary conditions, PE is found incidentally in 3.6% of cases, making this one of the most productive settings for detecting previously unsuspected emboli.

Pooled analyzes reveal the overall PE frequency across various indications at approximately 5.0%. Yet this figure varies substantially between patient populations: 3.9% in oncologic patients versus 6.6% in non-oncologic patients. Hence, radiologists evaluating chest CTs for acute pulmonary complaints should remain particularly alert for filling defects within pulmonary vessels.

Notably, PE was unsuspected (either incidental or unreported) in 54% of all PE events in oncologic patients compared with only 19% in non-oncologic patients. Even more concerning, over half of unsuspected PE events went entirely unreported on initial reads, underscoring the need for systematic vessel evaluation regardless of the original indication.

CT chest PE protocol in trauma and vascular cases

Trauma patients constitute a third high-risk group for PE detection. A systematic review and meta-analysis determined the overall prevalence of PE among trauma patients undergoing CT pulmonary angiography (CTPA) to be 18% (95% CI = 13-24%).

Femur fractures appear particularly associated with PE development, present in 12% of cases. Additional risk factors include head trauma, spine injury with neurological impairment, and lower limb injuries. Timing proves crucial, as approximately 29% of post-trauma PE occurs within the first four days following injury.

For trauma evaluation, CT protocols must balance the need for rapid assessment with diagnostic quality. The superiority of CT over chest radiography for thoracic trauma is well established; CT reveals notable pathology in patients with normal initial radiographs and in 20% of cases demonstrates more extensive injuries than initially suspected.

Standard trauma protocols typically include:

• Contrast administration with consideration for delayed acquisition (5 minutes) when active bleeding is suspected
• Evaluation for associated injuries including lung contusion (present in 17-70% of blunt chest trauma)
• Assessment for tracheobronchial injuries (rare but carrying 30% mortality)
• Screening for aortic injury (occurring in 0.5-2% of non-lethal motor vehicle accidents)

Given these statistics, radiologists should implement dedicated PE protocol whenever vascular injury is suspected. This approach becomes especially important since thrombotic burden varies between suspected and unsuspected cases, with unsuspected PE typically associated with lower thrombus mass.

 

 

Quantifying Thrombus Burden Using Mastora Score

Quantitative assessment of clot burden represents a critical component of modern PE protocol implementation. The Mastora score offers radiologists a standardized method for evaluating thrombus volume and distribution, thereby enabling more precise risk stratification and treatment planning.

Global obstruction percentage in oncologic vs non-oncologic patients

The Mastora scoring system divides the pulmonary arterial tree according to anatomical distribution, encompassing five mediastinal, six lobar, and twenty segmental arteries. Each vessel receives a score based on occlusion percentage: 1 for 1-24%, 2 for 25-49%, 3 for 50-74%, 4 for 75-99%, and 5 for 100% obstruction. The cumulative score can reach a maximum of 155 points, with higher values indicating greater thrombus burden.

In clinical practice, obstruction indices frequently differ between oncologic and non-oncologic populations. Studies demonstrate that central pulmonary embolism occurs more commonly in patients without malignancy, whereas peripheral emboli are more prevalent in cancer patients. This pattern has therapeutic implications, as central PE typically produces more extensive right ventricular strain compared to peripheral distribution.

Research examining clot burden reveals a profound relationship between Mastora scores and hemodynamic compromise. Patients with scores exceeding 21.3% demonstrate elevated pulmonary artery pressures (mean 36.0 ± 6.4 mmHg) compared to those with lower scores (mean 26.2 ± 6.4 mmHg). Furthermore, an even more dramatic increase occurs with scores above 50% (mean 39.4 ± 6.8 mmHg).

Segmental and lobar distribution patterns

Lobar distribution analysis shows predominant involvement of specific regions within the pulmonary circulation. Among patients with confirmed PE, 75% present with clots in two or more lobes, with the right lower lobe most frequently affected (85.4% of cases).

A thorough examination of 240 pulmonary lobes from 48 PE-positive patients revealed that 60.8% contained blood clots. Among affected lobes, most (72.6%) exhibited low clot burden (CTOIlobe between 1-50%), while 27.4% showed high obstruction scores (CTOIlobe above 50%). This distribution information proves valuable for protocol standardization and helps radiologists focus attention on commonly affected areas.

Perfusion measurements further illustrate the physiological impact of varying clot burdens. Lobar pulmonary blood volume (PBV) averages 13.7% (IQR 10.2-18.0%) in lobes without PE. In contrast, lobes with high obstruction scores demonstrate markedly reduced perfusion, with median PBV of only 6.5% (IQR 5.1-10.2%).

Number of affected vessels and embolus location

The relationship between vessel involvement and clinical outcomes underscores the importance of comprehensive PE protocol implementation. Multivariate analysis demonstrates that high obstruction scores independently influence lobar perfusion (p<.001), whereas clot location alone does not exert the same effect.

Embolus location substantially impacts diagnostic accuracy across imaging modalities. On a per-embolus basis, detection sensitivity for lobar PE reaches 79% with real-time MRI and 62% with MR angiography, compared to virtually 100% detection with CT-based PE protocols. For segmental PE, these sensitivities change to 86% and 83% respectively.

CT examination remains the gold standard, visualizing 97.62% of subsegmental arteries versus only 60.17% with MR angiography. This technical superiority explains why CT PE protocol timing and technique optimization remain essential components of effective PE management.

Clinical risk stratification increasingly relies on Mastora scores, with studies demonstrating clear correlation between scoring tiers and mortality risk. In one analysis, median Mastora scores were 11.0, 18.0, and 31.5 in low-risk, intermediate-low risk, and intermediate-high/high risk groups, respectively. This progressive elevation across risk categories underscores the score’s value in clinical decision-making and confirms its utility within comprehensive PE protocols.

 

 

Suspected vs Incidental vs Unreported PE: Key Differences

Pulmonary embolism categories differ substantially in their presentation, detection characteristics, and clinical implications. These variations necessitate specific PE protocol adaptations to ensure optimal patient outcomes.

Thrombus mass comparison across categories

Embolic burden varies markedly between PE detection categories. The thrombus mass is consistently lower in unsuspected PE compared with suspected PE and in unreported PE compared with incidental PE. This discrepancy explains why many incidental findings remain asymptomatic until detection. Quantitative analysis reveals that oncologic patients typically exhibit lower thrombus mass across all anatomical levels compared to non-oncologic patients. This pattern contributes to the higher prevalence of unsuspected PE in cancer patients.

The anatomical distribution also varies between categories. Prior studies demonstrate that central pulmonary artery involvement occurs more frequently in symptomatic cases, while peripheral emboli predominate in incidental discoveries. This distribution affects CT PE protocol timing considerations, as optimal contrast enhancement of peripheral vessels requires precise timing parameters.

Reporting errors and search satisfaction failure

Satisfaction of search (SOS) error represents a common pitfall in diagnostic radiology. This phenomenon occurs when radiologists prematurely end their search after identifying an initial abnormality. Upon discovering one finding, the radiologist’s cognitive attention shifts away from additional abnormalities, leading to potentially missed diagnoses.

Unreported PE represents a substantial clinical challenge, with studies showing 32-75% of incidental PE cases go unreported in initial readings. Even more concerning, a recent retrospective analysis found almost 80% of incidental PE cases remained unreported. This oversight occurs primarily due to:

1. Search patterns focused on the primary diagnostic question rather than vascular structures
2. Limited attention to peripheral pulmonary arteries, especially on non-PE protocol studies
3. Inadequate window settings for pulmonary artery visualization

Artificial intelligence tools show promising results in addressing these errors. One study found AI correctly identified 33 of 40 incidental PEs, including subsegmental emboli frequently missed in routine interpretations. Nevertheless, optimization remains necessary, as false-positive AI findings can lead to radiologist fatigue.

Clinical symptoms and diagnostic oversight

Contrary to conventional terminology, “incidental” does not necessarily mean “asymptomatic.” Upon retrospective review, approximately 75% of patients with incidental PE report at least one symptom potentially associated with acute PE. Patients with incidental PE experience fatigue (54% versus 20% in control patients) and shortness of breath (22% versus 8%) significantly more often than matched controls.

The clinical implications of missed diagnosis are substantial. Untreated patients with unreported incidental PE face a recurrent venous thromboembolism risk of 29.8% compared to 6.5% in control populations. Of note, recurrence rates vary by embolus location:

• Single subsegmental iPE: 20.9 events per 100 person-years
• Multiple subsegmental iPE: 52.0-72.0 events per 100 person-years
• More proximal iPE: 52.0-72.0 events per 100 person-years

In multivariable analysis, multiple subsegmental and more proximal incidental PE associate with recurrent VTE risk, while single subsegmental PE shows no substantial association (p=0.13). These findings inform management decisions, as the American Society of Clinical Oncology recommends case-by-case treatment for subsegmental incidental PE, weighing anticoagulation benefits against bleeding risks.

 

Imaging Protocols and Technical Considerations

Optimal detection of pulmonary emboli requires meticulous attention to technical parameters during CT acquisition. Technical refinements in protocol implementation substantially improve visualization across all vessel orders, thereby enhancing diagnostic confidence.

CT PE protocol timing and contrast administration

Precise timing represents the cornerstone of effective pulmonary artery opacification. Research demonstrates that with a 30-second contrast injection followed by a 10-second saline flush, the optimal temporal window for pulmonary artery enhancement exceeding 200 HU occurs between 16-41 seconds after injection initiation. Two primary approaches exist for achieving diagnostic quality: bolus tracking and test bolus techniques. Bolus tracking employs real-time monitoring at the main pulmonary trunk until a predetermined threshold (typically 100-150 HU) triggers acquisition. Alternatively, test bolus methodology utilizes a preliminary 20mL injection to generate a time-enhancement curve, determining scan delay through peak enhancement plus scanner-specific delay times.

Contrast protocols generally employ 60-80mL of iodinated contrast (370mg I/mL) at injection rates of 4-5mL/s. For patients with renal dysfunction, smaller volumes (25-35mL) can be utilized effectively with dual-energy techniques. Patient breathing instructions warrant careful consideration; normal rather than deep inspiration before breath-holding prevents transient interruption of contrast—a phenomenon where unopacified blood from the inferior vena cava dilutes contrast in the right atrium.

Slice thickness and collimation impact on detection

Collimation settings profoundly affect diagnostic accuracy across vascular territories. Multi-detector CT at 1.25mm collimation dramatically improves vessel visualization compared to 3mm settings—particularly for subsegmental arteries (76% versus 37% visibility). This enhanced detection capability translates directly to clinical outcomes; interobserver agreement for PE identification improves substantially with thinner collimation (κ=0.71-0.76 versus κ=0.28-0.54).

In routine clinical scenarios not primarily targeting PE detection, reconstructing acquired data with thinner slice thickness (1-1.5mm) provides images equivalent to dedicated CTPA studies. This practice enables incidental PE detection without additional radiation exposure, provided contrast delivery maximizes pulmonary arterial opacification.

Windowing techniques for pulmonary artery visualization

Window settings critically influence detection rates of subtle filling defects. Conventional soft tissue windows often render pulmonary vessels suboptimally due to excessive contrast density at acquisition times around 35 seconds. Instead, widened window settings (width 500, center 130 HU) offer superior visualization of the pulmonary arterial tree.

For dual-energy acquisitions, additional post-processing capabilities include generating material decomposition images and perfusion maps. Low kilovoltage monochromatic images (<60 keV) can salvage studies with suboptimal enhancement by artificially increasing vessel contrast. Furthermore, iodine-specific reconstructions enable quantification of perfusion defects, potentially aiding in risk stratification beyond simple embolus detection.

Ultimately, technical optimization must balance diagnostic accuracy against radiation exposure. Modern protocols incorporate dose modulation techniques and iterative reconstruction algorithms, maintaining image quality while minimizing radiation dose—particularly important for younger patients requiring PE evaluation.

 

Implications for Radiologists and Reporting Practices

Effective implementation of PE protocol requires radiologists to adopt standardized approaches for accurate detection and appropriate management of embolic findings. Considering that up to 50% of unsuspected PE events go unreported in initial readings, structured methodology becomes essential for comprehensive evaluation.

Checklist for reviewing pulmonary arteries

Systematic vessel assessment dramatically reduces oversight errors in CT interpretation. First, radiologists must evaluate all pulmonary arterial branches methodically, even when PE is not the primary indication. Second, review pulmonary arteries on at least two different reconstructions to maximize detection sensitivity. Third, pay particular attention to the right lower lobe, where 61% of overlooked emboli occur. Fourth, utilize optimal window settings (width 500-600, level 100-150) that enhance vessel visualization beyond standard mediastinal parameters. Finally, clearly document the level to which pulmonary arteries are adequately visualized (central, lobar, segmental, or subsegmental).

When to recommend follow-up or anticoagulation

Treatment decisions hinge upon clinical context and embolus characteristics. For nearly all acute PE cases, including incidental findings, anticoagulation therapy represents standard practice. Indeed, research shows anticoagulation reduces six-month recurrent VTE risk from 12% to 6.2% in untreated versus treated patients. Likewise, overall mortality decreases from 47% to 28-37% with appropriate intervention. For isolated subsegmental PE, consider lower extremity ultrasound to assess for concomitant DVT—found in 13-47% of incidental PE cases. The American College of Chest Physicians recommends identical management strategies for both suspected and incidental PE.

Reducing missed diagnoses in routine CT scans

Artificial intelligence tools offer promising solutions for enhancing detection rates. Recent studies demonstrate AI implementation reduced missed incidental PE from 44.8% to merely 2.6%. Similarly, time-to-consult decreased from 240.45 minutes to 6.72 minutes in AI-augmented workflows. Though AI tools achieve impressive specificity (99%), sensitivity remains suboptimal (41%). Integration challenges persist, as 7.3% of scans in one study went unanalyzed by AI due to technical issues. Yet, with proper implementation, AI augmentation can identify substantial numbers of initially unreported emboli—25 additional cases in one investigation.

 

 

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Conclusion

Pulmonary embolism remains a critical finding on CT scans that warrants meticulous attention from radiologists and clinicians alike. Throughout this review, we have examined the complex nature of PE detection across various clinical contexts, emphasizing the essential distinction between suspected, incidental, and unreported emboli. The prevalence data clearly demonstrates higher frequencies in specific populations, particularly oncologic patients undergoing follow-up imaging and those being evaluated for acute pulmonary disease.

Standardized PE protocols offer substantial benefits for detection rates across all vessel orders. Optimized contrast timing, appropriate collimation settings, and specialized windowing techniques collectively enhance visualization of filling defects that might otherwise escape detection. These technical refinements prove especially valuable when examining peripheral pulmonary vasculature, where incidental emboli frequently occur.

The Mastora scoring system provides radiologists with a powerful tool for quantifying thrombus burden and stratifying risk. Patients with higher obstruction percentages face greater hemodynamic compromise, underscoring the value of thorough vascular assessment even when PE is not the primary indication for imaging. Despite being labeled “incidental,” these findings often correlate with subtle clinical symptoms upon retrospective review.

Perhaps most concerning, unreported PE represents a persistent diagnostic challenge with potentially serious consequences. Between 32-75% of incidental emboli go unreported during initial interpretation, though emerging artificial intelligence tools show promise for reducing this oversight. When properly implemented, AI-augmented workflows dramatically decrease missed diagnoses and shorten time-to-consultation.

Clinical management decisions must consider embolus location and extent rather than discovery circumstances. Current evidence supports identical treatment approaches for both suspected and incidental PE, with anticoagulation therapy recommended for nearly all acute cases regardless of detection method. This practice aligns with research showing substantially reduced mortality and recurrence rates following appropriate intervention.

Radiologists must therefore adopt systematic vessel evaluation procedures for all chest CT interpretations. Structured checklists, standardized window settings, and comprehensive documentation of visualization levels will minimize diagnostic errors. Additionally, clear communication of findings and management recommendations ensures optimal patient care following PE detection.

As imaging technology continues to evolve, radiologists must balance technical innovation with clinical judgment. Through meticulous attention to protocol implementation and thorough vascular assessment, the radiology community can effectively address the challenge of incidental PE and ultimately improve patient outcomes across diverse clinical settings.

Key Takeaways

This comprehensive guide reveals critical insights for managing incidental pulmonary embolism findings that can significantly impact patient outcomes and diagnostic accuracy.

• Incidental PE is surprisingly common: Found in 1.1% of coronary CTs and 3.6% of oncologic scans, with cancer patients showing 54% unsuspected PE rates versus 19% in non-cancer patients.
• Up to 75% of “incidental” PE goes unreported: Despite being labeled incidental, these findings require identical treatment to suspected PE, as untreated cases face 30% mortality versus 2-10% when treated.
• Technical optimization dramatically improves detection: Using 1.25mm slice thickness increases subsegmental artery visibility from 37% to 76%, while proper windowing (width 500-600, level 100-150) enhances vessel visualization.
• Systematic vessel review prevents diagnostic errors: Implementing structured checklists and evaluating pulmonary arteries on multiple reconstructions reduces missed diagnoses, especially in high-risk areas like the right lower lobe.
• AI integration shows promising results: Artificial intelligence tools reduced missed incidental PE from 44.8% to 2.6% and decreased consultation time from 240 minutes to under 7 minutes.

The key message is clear: radiologists must maintain vigilance for PE across all chest CT examinations, regardless of the original indication, as these “incidental” findings carry the same clinical importance and treatment requirements as suspected cases.

 

Frequently Asked Questions:

FAQs

Q1. What is incidental pulmonary embolism (PE) and how common is it? Incidental PE refers to pulmonary embolism discovered on CT scans performed for reasons other than suspected PE. It’s found in about 1.1% of coronary CT scans and 3.6% of oncological CT scans, with higher rates in cancer patients.

Q2. How does the Mastora score help in assessing pulmonary embolism? The Mastora score is a standardized method for evaluating thrombus volume and distribution in pulmonary arteries. It helps quantify clot burden, enabling more precise risk stratification and treatment planning for patients with PE.

Q3. What are the key differences between suspected and incidental PE? Suspected PE is diagnosed when imaging is ordered for PE symptoms, while incidental PE is found unexpectedly. Incidental PE typically has a lower thrombus mass and is more often peripheral, while suspected PE tends to involve central pulmonary arteries and have higher clot burden.

Q4. How can radiologists improve detection of incidental PE? Radiologists can improve PE detection by using thin slice thickness (1-1.5mm), optimizing window settings (width 500-600, level 100-150), systematically reviewing all pulmonary arteries, and paying special attention to commonly affected areas like the right lower lobe.

Q5. Should incidental PE be treated differently from suspected PE? No, current guidelines recommend identical management strategies for both suspected and incidental PE. Anticoagulation therapy is generally recommended for nearly all acute PE cases, regardless of how they were discovered, as it reduces mortality and recurrence rates.

 

 

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