Purpose: To measure the age-dependent changes of anatomical positions and relations between the trachea, cricoid cartilage (CC), and innominate artery (IA) in adults by computed tomography (CT).
Methods: A retrospective cohort reviewing images of 127 consecutive adult patients who underwent CT angiography (CTA) of the neck. The trachea-to-IA (T-IA) distance was measured as the minimal horizontal distance between them. The vertical distance between the CC and the IA was measured between the axial section, demonstrating the CC's inferior border to the axial section at the level of the T-IA measurement.
Results: Images of 125 patients (median age 53 years, range 18-89; 74 males) were reviewed. The mean T-IA distance was 2.3 ± 1.1 mm for males and 1.7 ± 0.9 mm for females (P = 0.002). The vertical C-IA distance was 44.2 ± 11.4 mm and 49.5 ± 12.5 mm for males and females, respectively (P = 0.01). Age correlated negatively with the vertical C-IA distance (P < 0.0001) and positively with the T-IA distance (P < 0.0001). The rate of IA variants was 23.2%, with no significant difference between the measurements of distances among patients with or without IA variants.
Conclusions: This is the first description of the relationships between the trachea, CC, and IA distances in adults as depicted on CTA. The T-IA distance becomes larger while the T-CC distance becomes shorter with age.
Keywords: Innominate artery; Trachea; Tracheo-innominate fistula; Tracheostomy.