Identification of pulmonary embolism: diagnostic accuracy of venous-phase dual-energy CT in comparison to pulmonary arteries CT angiography.

OBJECTIVES: To evaluate the diagnostic accuracy of venous-phase dual-energy computed tomography (VP-DECT) in the identification of PE compared with standard CT pulmonary angiography (CTPA).

METHODS: This prospective IRB-approved study included 61 consecutive oncology patients (35 females, 26 males, mean age 66.91 years) examined by CTPA and VP-DECT. DECT data were post-processed on a SyngoVia workstation to obtain monoenergetic images (MEI+). The diagnosis of PE was based on the presence of any vascular perfusion defects. DECT images were evaluated independently by two radiologists (8 and 16 years of experience). A consensus reading of CTPA images (two senior radiologists, 18 and 24 years of experience) represented the reference for diagnosis. The diagnostic accuracy values of VP-DECT on a per-patient and per-lobe basis were assessed. Interobserver agreement was calculated using k-statistics. A value of p < 0.05 was considered statistically significant.

RESULTS: Thirty of 61 patients (49.18%) were diagnosed with PE by CTPA, with 57/366 lobes being involved (15.57%). The sensitivity and specificity of the per-patient analysis of VP-DECT images were 90.0% (27/30) and 100% (31/31) respectively, for both readers. As concerns the per-lobe analysis, the sensitivity ranged from 100% for the right lower lobe to 50% for the left upper lobe for reader 1, and from 100% for the left upper lobe to 69.23% for the lingula for reader 2. The interobserver agreement ranged from 0.8671 (patients' analysis) to 0.6419 (lobes' analysis).

CONCLUSION: VP-DECT could be considered an accurate imaging tool for diagnosing PE in a selected, high-prevalence population, compared with CTPA.

KEY POINTS: • With regard to the patients' analysis, venous-phase DECT sensitivity and specificity in diagnosing pulmonary embolism were 90% and 100%, respectively, for both readers. • With regard to the lobes' analysis, the sensitivity ranged from 100 to 50%, for reader 1, and from 100 to 69.23%, for reader 2, respectively. • The sensitivity and specificity of lung perfusion maps obtained from venous DECT were 73.33% and 67.74% as concerns the patients' analysis and 71.92% and 75.72% as regards the lobes' analysis, respectively.