Iodine concentration in the lung parenchyma in relation to different inspiratory depths during CT pulmonary angiography

Abstract

Objectives: This study aimed to investigate the impact of changing inspiratory depth from end- to mid-inspiratory level on the iodine concentration in the lung parenchyma and main pulmonary artery in dual-energy CT pulmonary angiography.

Methods: This retrospective study included patients who underwent dual-energy CT pulmonary angiography from July 2020 to June 2023. Patients were instructed to hold their breath at end- and mid-inspiratory levels before and after January 2022, respectively. By placing regions of interest on the lung lobes and main pulmonary artery in the iodine map, their iodine concentration was recorded.

Results: In end- and mid-inspiratory command, 173 (mean age: 63.4 ± 17.0 years; 68 males) and 179 (mean age: 65.1 ± 15.4 years; 62 males) patients, respectively, were included. The mean iodine concentrations of the right upper, right middle, right lower, left upper, and left lower lobes were 0.81/0.91, 0.67/0.74, 1.06/1.07, 0.85/0.95, and 1.07/1.11 mgI/mL, respectively, for the end-/mid-inspiratory level. The multivariable regression analysis revealed inspiratory depth as a significant factor for iodine concentration of the right upper, right middle, and left upper lobes. Main pulmonary artery iodine concentration in mid-inspiratory depth (13.21 mgI/mL) was higher than that in end-inspiratory depth (12.51 mgI/mL) (P = .129), and a statistically significant difference was observed in the patient group with a body weight of ≥70 kg (P = .015).

Conclusions: Changing inspiratory depth from end- to mid-inspiratory level has a significant impact on the iodine concentration in the upper and right middle lobes in dual-energy CT pulmonary angiography.

Advances in knowledge: Changing inspiratory depth from end- to mid-inspiratory level has significantly increased the iodine concentration in the right upper, right middle, and left upper lobes.

Keywords: CT angiography; contrast media; lung; multidetector CT.