Eustachian Tube: Computed Tomography Analysis

Evaluation of Eustachian tube dimensions by temporal bone computed tomography in patients with chronic otitis media

OBJECTIVE

To clarify the relationship between Eustachian tube dimensions and chronic otitis media aetiology using temporal bone computed tomography.

METHODS

The data of 231 adults who had undergone surgery for unilateral chronic otitis media were reviewed retrospectively. Diseased and healthy ears were enrolled in groups 1 and 2, respectively. Group 1A included chronic otitis media with cholesteatoma (n = 28) and group 1B included chronic otitis media without cholesteatoma (n = 203). The Eustachian tube dimensions of groups 1 and 2 were compared, to clarify the relationship between the Eustachian tube dimensions and chronic otitis media aetiology. Groups 1A and 1B were compared to assess the effect of Eustachian tube dimensions on cholesteatoma development.

RESULTS

The Eustachian tube was shorter, narrower and located more horizontally in ears with chronic otitis media. No significant difference was found between groups 1A and 1B.

CONCLUSION

Eustachian tube dimensions are closely related to chronic otitis media aetiopathology, but are not related to cholesteatoma development.

CT and MRI in the Preoperative Planning of Balloon Dilation of the Eustachian Tube: Literature Review

Balloon dilatation of the Eustachian tube (BET) is a surgical treatment method for Eustachian tube dysfunction (ETD), which relieves the symptoms in the majority of cases. However, there are potential intraoperative risks associated with BET; the decision-making process with regard to indications for BET is not standardized up to date. The objective of this study was to review the role of computed tomography (CT) and magnetic resonance imaging (MRI) in the preoperative planning of BET. The literature review is based on a database search performed in August 2022. BET is classified into transtympanic and nasopharyngeal. CT of the temporal bone provides good visualization of the site of obstruction, which allows to choose the adequate approach. Transtympanic approach is associated with risks of internal carotid artery damage due to possible carotid canal anomalies. This risk can be prevented with preoperative CT scan of the temporal bone. In case of nasopharyngeal BET, there is no sufficient data considering risks of possible artery damage, although CT can provide accurate measurements of ET. MRI is useful for differential diagnosis of conditions imitating ETD, such as endolymphatic hydrops and nasopharyngeal carcinoma. Thus, it is feasible to perform CT and MRI before BET to personalize the management of ETD patients.

Intravascular Ultrasonography (IVUS)-A Tool for Imaging the Eustachian Tube?

The Eustachian tube (ET) has a key role in the pathogenesis of otitis media. Until now, there has been a lack of meaningful imaging methods to investigate the ET and its surrounding tissue. The aim of the current study was to investigate the possibilities of imaging the ET using Intravascular Ultrasonography (IVUS). ETs from sheep were scanned ex vivo and in vivo with different IVUS probes. In addition to native ETs, water was also used to improve coupling. Scans were subsequently compared with histological sections and a 3D model of the ET. In addition, ETs with a stenosis induced by a hyaluronic acid depot, after stent insertion, and during lower jaw movement were examined. The IVUS catheter was inserted into the ET lumen without any problems or injuries in all cases. The surrounding structures of the ET were identified in the ultrasound image. In addition, a change in size of the ET lumen due to movement was observed, and the position of the stent and the depot of hyaluronic acid could be examined. With the use of IVUS, a non-invasive possibility to examine the ET over its course with the adjacent structures as well as after different treatments is presented.

Investigations on the potential of optical coherence tomography as an imaging tool for eustachian tube

The purpose of this study was to explore the feasibility of eustachian tube optical coherence tomography (ET-OCT) for imaging the pharyngeal region of the eustachian tube (ET). Ten subjects with ear complaints underwent ET-OCT guided by nasal endoscopy, and ET-OCT examination was performed on both sides of each subject's ETs. The process and resulting images were analysed. Ten subjects ranging from 21 to 73 years old (45 ± 14.77) were enrolled in this study. Eighteen ET-OCT imaging examinations were completed. The mean duration of each examination was 2.80 ± 1.62 min (ranging from 2 to 7 min). There were no adverse events or complications. In some subjects, the ET-OCT images clearly presented the microstructures of the ET wall, including the lumen, mucosa, submucosa, cartilage and plica. However, in some subjects, it showed different characteristics, such as an unclear hierarchy and secretions in the lumen. ET-OCT may help to distinguish the structural composition of the ET and elucidate related pathophysiological mechanisms. It is a valuable imaging tool suited for the ET, with potential diagnostic value in determining the morphology of the lumen, intraluminal mucosa and submucosal tissue in the pharyngeal region of the ET.