CT imaging of the Eustachian tube using focal contrast medium administration: a feasibility study in humans

Abstract

Background: Several methods of imaging the Eustachian tube have been tested in the last century, although neither has led to an established method. The introduction of balloon Eustachian tuboplasty (BET) has revived the request for Eustachian tube (ET) visualization in patients with chronic Eustachian tube dysfunction. Many institutions perform preoperative computed tomography (CT) scans of the temporal bone and epipharynx before BET. Purpose We hypothesize that the injection of a contrast medium into the tympanic cavity is safe and feasible and can evolve the CT scan by visualizing the ET lumen and, potentially, the level of obstruction. This study is the initial feasibility study for such a human application. Material and Methods Ten minutes before a CT scan, diluted iodixanol was injected into the middle ear in 18 patients planned for BET due to otitis media with effusion. Five patients with Meniere's disease were controls. Any immediate or delayed adverse events were recorded. Masking of adjacent bony structures in the middle ear on the CT images was evaluated and the most caudally visible contrast medium between the middle ear and epipharynx recorded. Results There were no serious adverse events. One patient reported transitory vertigo. The contrast medium did not mask middle ear structures, apart from the tympanic membrane. The level of contrast medium passage could be assessed. Conclusion Visualizing the ET lumen in humans using intratympanic contrast medium is feasible and safe and does not obscure other valuable image information in a preoperative CT scan.

A new “practical" plane for Eustachian tube measurements and its application in predicting middle ear dysfunction in patient with acquired cholesteatomas

“…The ET lumen path length can be measured from cadaveric specimens, which were finely sectioned and 3D reconstructed to account for the curvature of the ET at the bony cartilaginous junction [ 6 ]. The measurement of ET lumen path length is not possible on CT scans unless under special circumstance such in patients with patulous ET [ 11 ], or with invasive injection of contrast media into the middle ear cleft [ 10 ].…”

“…The increased availability of high-resolution temporal bone computed tomography (CT) and the use of cone-beam CT, combined with the advent of multiplanar reconstruction (MPR) has made it possible for ETs to be measured on imaging studies [ 1 – 3 , 10 , 11 ]. A review of the literature revealed a range of methods in measuring ET angle and lengths, as summarised in Table 1 .…”