From the Guidelines
A filling defect spotted on a computed tomography (CT) scan in the coronal fashion, suggestive of pulmonary embolism, is most likely located in the pulmonary arteries, specifically in the segmental or subsegmental branches. This is based on the high sensitivity and specificity of CT pulmonary angiography (CTPA) in detecting filling defects in the pulmonary vasculature, as reported in a study published in the Journal of the American College of Radiology 1. The study highlights that CTPA is highly sensitive and specific in detecting pulmonary embolism, with discrepancies with conventional angiography mainly at the subsegmental level.
Key Points
- CTPA is the standard of care for PE detection, with high sensitivity and specificity 1
- Filling defects in the pulmonary vasculature are typically located in the segmental or subsegmental branches of the pulmonary arteries
- The high resolution of CTPA makes it possible to detect filling defects in distal subsegmental arteries as small as 2 to 3 mm in diameter 1
- The combination of multi-detector CTPA and high-specificity D-dimer testing has very high positive and negative predictive values 1
Clinical Implications
- A positive CTPA result combined with high or intermediate suspicion on clinical assessment has a high positive predictive value 1
- The adjunctive use of CT venography with CTPA improves the sensitivity of detecting DVT, with similar specificity, thereby increasing the overall accuracy of the diagnosis of thromboembolic disease 1
- CTPA can also identify signs of right ventricular dysfunction that may have prognostic significance or implications for treatment 1
From the Research
Location of Filling Defect on CT Scan
The location of a filling defect spotted on a computed tomography (CT) scan in the coronal fashion, suggestive of pulmonary embolism, can be identified in the central, lobar, segmental, or subsegmental pulmonary arteries 2.
Possible Locations
- Central pulmonary arteries
- Lobar pulmonary arteries
- Segmental pulmonary arteries
- Subsegmental pulmonary arteries
Diagnostic Approach
The diagnosis of pulmonary embolism can be made using spiral computed tomography pulmonary angiography (CTPA) 2, which is the best way to evaluate the possibility of pulmonary embolism in a patient with a pleural effusion.
Clinical Presentation
Patients with pulmonary embolism may present with dyspnea, tachypnea, or pleuritic pain 3, and the presence of pleuritic chest pain in a patient with a pleural effusion is highly suggestive of pulmonary embolism 2.
Imaging Techniques
Imaging techniques such as computed tomography pulmonary angiography or ventilation-perfusion scans are necessary for objective diagnosis of pulmonary embolism 4.