Perfusion defects on dual-energy CTA in patients with suspected pulmonary embolism correlate with right heart strain and lower survival.

Objectives: To evaluate the utility of perfusion defects on dual-energy CT angiograms (DECTA) in assessing the clinical severity of pulmonary embolism (PE).
Methods: We retrospectively reviewed 1136 consecutive diagnostic DECTA exams performed on patients with suspected PE between January 2014 and September 2014. Presence and location of obstructive and non-obstructive PE, right ventricular to left ventricular ratio (RV/LV ratio), and inferior vena cava (IVC) backflow were recorded. Iodine maps were reviewed to establish the presence of perfusion defect and its extent was determined through a score-based segmental impaired perfusion. Subsequently, the perfusion defect scores were correlated with clinical parameters including vital signs, electrocardiogram (ECG) abnormalities, echocardiogram findings, troponin, and brain natriuretic peptide (bnp) levels. Clinical information regarding primary cancer diagnosis, oncologic stage, and date of death if applicable was also recorded.
Results: Of the 1136 diagnostic iodine maps, 96 of these patients had perfusion defects on iodine maps. After uni- and multivariate analysis, significant correlation was found between the presence of a perfusion defect and RV/LV ratio (p = 0.05), IVC backflow (p = 0.03), elevated troponin (p = 0.03), and right heart dysfunction as determined on an echocardiogram (p = 0.05). The greater the perfusion defect score, the higher the likelihood of IVC backflow (p = 0.005) and obstructive PE (p = 0.002). When adjusted for oncologic stage, patients with a perfusion defect and a higher perfusion defect score had a higher mortality rate (p = 0.005).
Conclusion: The presence of a perfusion defect correlates with several parameters evaluating PE severity. A perfusion defect and higher perfusion defect score were associated with a lower survival.
Key Points: • Detection of perfusion defects on dual-energy CT angiograms and its extent correlates with right heart strain in the setting of pulmonary embolism. • The presence and extent of a perfusion defect in patients with pulmonary embolism are associated with lower survival.