The role of MRI in the diagnosis and management of tracheal diverticulum

Abstract

Background: Multidetector CT is currently the best imaging method for detecting tracheal diverticulum (TD). Compared with CT, MRI is radiation-free and has higher resolution. However, the MRI characteristics of this disease have not been previously reported. The present retrospective study compared the MR and CT imaging features of TD, aiming to examine the role of MRI in TD diagnosis and management.

Methods: Imaging data were collected in 26 TD patients divided into two groups, including the uninfected and infected groups. The MR and CT imaging features (size/wall/channel) of uninfected patients were compared. The performances of MRI and CT in diagnosing and monitoring therapeutic efficacy in infected TD patients were comparatively assessed.

Results: The uninfected group comprised 25 cases with 25 lesions confirmed by CT, including 23 lesions (92%) detected by MRI, with an average diameter of 8.5 mm (range from 3 to 15 mm). Meanwhile, the average diameter was 7.8 mm as measured by CT (range from 2.8 mm to 14.7 mm). The lesion diameters of the two cases not detected by MRI were 2.3 mm and 2 mm. MRI detected walls of all the 23 lesions (23/23), while CT detected no wall (0/23). CT showed channels in 18 lesions (18/23) versus3 for MRI (3/23). The infected case presented with a paratracheal abscess; MRI clearly showed a relationship between the abscess and the trachea, while CT could not show the lesion source. MRI also sensitively showed the whole process of lesion absorption.

Conclusions: MRI can be used as a supplementary method for TD diagnosis, providing information about the wall that cannot be obtained by CT. MRI is superior to CT in diagnosing infected TD cases presenting with a paratracheal abscess, and in monitoring therapeutic efficacy in these patients.

Keywords: CT; MRI; Paratracheal air cyst; Tracheal diverticula.

Fig. 1

The uninfected group comprised 25 patients with 25 lesions confirmed by CT, including 23 lesions (92%) detected by MRI

Fig. 2

Axial CT image (a) in lung window showing a 5-mm diverticulum along the right posterolateral wall of the upper trachea (arrow). Axial T1WI (b) and T2-TIRM (c) showed a circular air-filled cystic lesion (no signal area) just behind the right side of the trachea (arrow). T2-Tirm clearly showed the slightly high signal wall of the lesion. Communication between the air cyst and the trachea was not seen in CT or MR images. A schwannoma in the right supraclavicular fossa is shown (arrowhead)

Fig. 3

Axial CT image showing a tracheal diverticulum just behind the upper trachea (arrow)

Fig. 4

Axial CT image (a) showing a lower-density mass just behind the upper trachea (arrow). The small bubble inside the lesion suggests it may be an abscess. No enhancement was found after contrast injection (b). CT could not identify the origin of the lesion

Fig. 5

Axial T2-TIRM (a) showed a high signal mass behind the upper trachea (arrow) with an irregular and ill-defined margin. The sign that local thickening and signal increase of posterolateral wall of the upper trachea (arrowhead) suggests that the lesion may arise from the tracheal diverticulum. The esophageal wall was intact. The lesion gradually resolved, and the signal was gradually decreased after 2 days (b), 4 days (c), 7 days (d) and 21 days (e) of conservative treatment