Paratracheal air cysts on thoracic multidetector CT: incidence, morphological characteristics and relevance to pulmonary emphysema

Objective To determine the incidence, morphological characteristics and relevance of paratracheal air cysts (PTACs) with pulmonary emphysema, as seen on thoracic multidetector CT (MDCT). Methods The CT images of 854 consecutive patients who underwent thoracic MDCT during a period of 2 months at our institution were reviewed. 538 of the patients were male and 316 were female. The incidence, size and shape of the PTACs and their relation to pulmonary emphysema were retrospectively analysed. Results Among the 854 patients, 69 (8.1%) had PTACs. 37 (6.9%) of the 538 male patients and 32 (10.1%) of the 316 female patients had PTACs. The highest prevalence of PTACs (25 patients, 11.2%) was found in those who were in the sixth decade of life. 48 (69.6%) PTACs measured 3–10 mm at the longest diameter and 33 (47.8%) were elongated on the coronal section images. 12 (17.4%) patients with PTACs had underlying gross morphological emphysema. The relationship between the presence of PTACs and the presence of emphysema an...