Objective: This study assessed the utility of dual-energy pulmonary CT angiography (CTA) for noninvasive assessment of regional pulmonary perfusion in patients with chronic thromboembolic pulmonary hypertension (CTEPH). Regional perfusion abnormalities were correlated with hemodynamic parameters and structural abnormalities on pulmonary CTA.
Subjects and methods: Twenty patients with CTEPH (11 men and nine women; mean age, 61.5 years) underwent pulmonary CTA with a dual-energy technique. Right heart catheterization data were available in 15 cases. Scan parameters were as follows: tube A, 140 kV (75 mA); tube B, 80 kV (300 mA); gantry rotation, 500 milliseconds; pitch, 0.5; and collimation, 14 × 1.2 mm. An iodine map was generated via three-material-decomposition and was scored for extent of hypoperfusion. Correlation was made with mosaic attenuation pattern, extent of vascular obstruction, and right heart hemodynamics. Iodine attenuation values were analyzed within completely occluded, partially occluded, and disease-free lobes.
Results: A strong correlation existed between dual-energy CT-derived perfusion and mosaic attenuation pattern when both lobar (r > 0.6; n = 20; p < 0.006) and whole-lung scores were assessed (r = 0.77; n = 20; p < 0.001). There was no statistically significant correlation between dual-energy CT perfusion and vascular obstructive index, mean pulmonary artery pressure, or pulmonary vascular resistance (p > 0.08). Of 42 completely occluded lobes, 27 (64%) had demonstrable residual perfusion (mismatching), suggesting that blood supply was maintained via systemic collaterals.
Conclusion: Dual-energy CT can offer a "one-stop" assessment of anatomy and perfusion in CTEPH. The additional information provided by dual-energy CT could have a future role in helping guide patient selection for thromboendarterectomy surgery.