Description:
<jats:sec><jats:title>Background</jats:title><jats:p> Computed tomography pulmonary angiography (CTPA) has evolved as the gold standard for diagnosing pulmonary embolism. However, subsegmental arteries are often not assessed to do insufficient attenuation. </jats:p></jats:sec><jats:sec><jats:title>Purpose</jats:title><jats:p> To evaluate the influence of simultaneous bilateral versus unilateral injection of a fixed amount of contrast media on pulmonary artery opacification and image quality in CTPA. </jats:p></jats:sec><jats:sec><jats:title>Material and Methods</jats:title><jats:p> In this institutional review board-approved prospective study, 180 patients (91 women, mean age 61.9 ± 16.5 years) referred for CTPA (100 kV) due to suspected pulmonary embolism were randomized in groups of 45 patients each, with either unilateral (A:4 mL/s; B:6 mL/s) or bilateral (C: 6 mL/s; D: 8 mL/s) (Y-shaped line) injection of 50 mL contrast media. Attenuation was assessed including the subsegmental arteries (4th order). Image quality was evaluated by two readers in consensus using a three-point grading scale (3 = excellent image quality, no artifacts, 1 = non-diagnostic). </jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p> Mean pulmonary artery attenuation was significantly higher with bilateral injection (1st to 3rd order: A: 303.6 ± 8.8HU; B: 371.1 ± 11.0HU vs. C: 443.2 ± 24.1HU; D: 562.3 ± 15.3HU, P < 0.001). Evaluation of subsegmental arteries was feasible for all patients in groups B–D, but only in 36/45 (80%) patients in group A. Subsegmental attenuation was significantly higher with bilateral injection (A: 284.7 ± 12.1HU; B: 367.4 ± 12.1HU vs. C: 494.2 ± 21.5HU; D: 562.3 ± 26.7HU, P < 0.001). Image quality was diagnostic for all patients but best for group C (A: 2.15 ± 0.4; B: 2.14 ± 0.5; C: 2.92 ± 0.3, and D: 2.51 ± 0.5). </jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p> Using the same amount of contrast media, bilateral injection yields higher pulmonary artery attenuation and better image quality than unilateral injection. This technique may improve subsegmental pulmonary artery assessment. </jats:p></jats:sec>