Keywords:
Pathology, Embolism / Thrombosis, Acute, Observer performance, Education, CT-Angiography, CT, Vascular, Pulmonary vessels, Cardiovascular system
Authors:
S.-M. O'Hanlon, T. Wooding, A. Mittal, Y. D. Weerakkody; Perth/AU
Purpose
Background
Pulmonary embolism is a heterogeneous,
potentially life-threatening entity which may have variable clinical manifestations and imaging appearances.
Imaging plays an important role in the diagnosis of pulmonary emboli with advances in computed tomography pulmonary angiogram (CTPA) techniques leading to improvements in diagnostic sensitivity.
The extent and distribution of emboli within the lungs have been minimally studied.
CTPA is a commonly performed investigation,
including in patient populations whose underlying condition may influence the diagnostic performance of the modality.1 Patients with chronic obstructive pulmonary disease (COPD) are considered to be at an increased risk of developing pulmonary emboli,
possibly in relation to inactivity,
heart failure,
and advanced age.2 There is an altered distribution of ventilation/perfusion ratios due to the pathological changes that occur in COPD.1 With a known preferential upper zone architectural destruction in COPD,
it is postulated that this may result in greater perfusion of the lower lobes. Therefore it is intuitive that pulmonary emboli may be more prevalent within the lower lobes in those with COPD compared to patients without COPD.
With increased utilisation of cross-sectional imaging in the follow-up of malignancy,
more cases of pulmonary emboli are being identified in recent years.
Isolated sub-segmental or incidental pulmonary emboli are usually found in patients with few or no classic symptoms.
The 2016 Cochrane review of anticoagulant treatment for subsegmental pulmonary embolism reported that there is no randomised controlled trial evidence for the effectiveness and safety of anticoagulation therapy versus no intervention in patients with isolated or incidental subsegmental pulmonary emboli.3 This highlights the importance of pulmonary emboli location given current controversy with regards to treatment of certain peripherally-located embolic events.
A further understanding of the distribution of pulmonary emboli and factors that may influence this,
including the presence of COPD changes and malignancy,
may improve radiologists' CTPA detection efficiency,
especially in emergent reporting environments.
Aims
- Investigate the anatomical distribution of pulmonary emboli detected on CTPA.
- Investigate the role of gender,
CT established COPD changes and malignancy on the anatomical distribution of pulmonary emboli.