Comparison Of Three 3D Modalities Based On MSCT: The Preoperative Assessment Of Ossicular Chain In Patients With Otitis Media

Otitis media, which is one of the most common diseases in Otology, especially the chronic suppurative otitis media and the cholesteatoma, decreases the patients'life quality dramatically. The patient will demonstrate conducitive hearing loss due to his ossicles was destroyed during the course. Currently, the general principle for the treatment of this disease is to improve patient's hearing to the utmost under the precise of thorough elimination of pathological tissue and avoidance to recurrence. For this purpose, patients will accept tympanoplasty and ossiculoplasty. It is well known that patients with different destroyed ways of ossicules need different types of ossiculoplasty. Therefore, it is very important for surgeons to know the ossicles' destroyed ways exactly. In addition, we can accurately forecast patients'hearing level after operation based on this information.Recently, there are some indirect marks for the diagnosis of ossicles abruption, such as the pathological tissue's site and ABG, whose low sensitivity and specificity are used to be proved. With the development of the HRCT, it is possible for us to observe the ossicles directly. However, owing to their minute size and complex relationship with the rest two, we can not wholly observe any ossicle in any one of the conventional axial or coronal images. For better diagnosis, we must mentally stack up multiple 2D planar images to reconstruct a complete 3D image. Nevertheless, the results are commonly dissatisfactory.The 3D reconstruction based on the MSCT facilitates us to observe the ossicules three-dimensionally and directly owing to the hard ware and soft ones development. To date, there have been some different 3D reconstruction ways, which were all proved to be valuable respectively. The following three modalities, MPR (multiplanar reformation), SSD-based CTVE (based on the surface shadow display) and VR (volume rendering), have been commonly used to reconstruct the middle and inner ear. However, different people had different opinions on these modalities'value, In addition, most of these researches mainly focused on the normal people or the cases with well aerated mastoid and middle ear cavity, such as the patient with abnormal ossicles or the one after trauma or operation. There has been a dearth of literature on the comment on the ossicles'status of the patient with chronic suppurative otitis media or the cholesteatoma, let alone the value comparative research among these three aforementioned different approaches.The study was composed of two parts. The first one was the research on the normal people. In this section, we would be familiar with the anatomy of the ossicles and the 3D reconstruction ways. What'more, we would assess the comparative value about these three modalities. The second part was the research on the patient with chronic suppurative otitis media or cholesteatoma. In this part, we also wanted to make a comparison of the three ones to diagnose the states of the ossicles, which was confirmed by the surgery.The aim of this part of the research was to examine and assess their comparative values of the three modalities. In this section we reviewed 32 human ears of 18 patients accompanied by normal pure tone audiograms, type-A tympanogram and normal HRCT characteristics, whose ossicular chains were reconstructed by the three aforementioned approaches and assessed via the three-point scoring system.The HRCT-based modalities could demonstrate a 3D image of the ossicular chain, except that of the footplate on the SSD-based CTVE. On the qualitative assessment, the efficacy of the MPR and VR, which were both superior to the SSD-based CTVE (P<0.05), presented no statistical significance among the major and/or hyperdense structures (P>0.05). As regards the lateral process of the malleus, VR was found to be significantly superior to the MPR and SSD-based CTVE (P<0.05), both of which, however, showed no significant comparative differences (P>0.05). Moreover, the three modalities showed little value for the lenticular process; however, MPR demonstrated superiority to the other two comparatively. What's more, the three modalities in terms of efficacy were found to be comparatively significant for representing the anterior crus and footplates of the stapes, respectively (P<0.05). In addition, regarding the posterior arch and head of the stapes, there were no differences between the technology of MPR and VR, which were both superior to the SSD-based CTVE technology. Besides, when it comes to the joints among the ossicles, the three modalities were of little value, since they demonstrated little representation of their inside interiors but only the morphous and location. Statistically, no significant difference were found about the incudostapedial joint (P>0.05); as for the malleoincudal joint, however, it was found that MPR was significantly superior to VR and SSD-based CTVE (P＜0.05).In conclusion, the modalities could demonstrate a 3D image of the ossicular chain, except that of the footplate on the SSD-based CTVE. Both the MPR and VR showed no significance among most of the structures of the ossicular chain, however, they all superior to the SSD-based CTVE. And comparing with MPR, VR images are the real 3D images and are the more valuable approach.The aim was to explore the value of these three aforementioned approaches in the patients with otitis media. The patients with more than 3-year-history of otitis media, who would accept pre-operation CT examinations and tympanoplasty were enrolled in this section of the research. However, some patients, who could not be confirmed for their ossicles'condition in the operation or accepted tympanoplasty more than one month after CT examination, were excluded. All the suitable cases' ossicular chains were reconstructed three-dimensionally using the three modalities respectively and assessed by three radiologists via a three-scoring system. Moreover, the conditions of those patients'ossicular chains were observed, assessed and recorded in the operation by a similar three-scoring system. Then, we discussed those modalities'value by comparison with each other.For display of the malleus, the three modalities showed no significant differences in the Youden's index and coincidence rate; as regard the incus, the Youden's index and coincidence rate of the VR and MPR demonstrated no differences, however, both higher than the SSD-based CTVE. For representation the stapes, the value of these three modalities is very low. The SSD-based CTVE could not detect the footplate of the stapes, and the Youden's index and coincidence rate of the MPR technology for the footplate were higher than those of the VR technology; in addition, the Youden's index and coincidence rate of the VR technology for showing the anterior and posterior arch and the head of the stapes was inferior to the other two. Regarding the joints among these ossicles, the VR technology showed superiority to the other two in demonstration of incudomalleolar joint; and the MPR technology represented superiority to the other two in representation of the incudostapedial joint. In conclusion, for patient with otitis media, the value of the MPR and VR technology in assessing the integrity of the malleus and incus showed no significant differences, however, both were superior to the SSD-based CTVE technology; and for the stapes, those three modalities showed little value. In addition, for the joints, the VR technology could be helpful for observation of the relationship among the three ossicles. What's more, the VR technology was the real 3D one, which did not need complex operations. Hence, the VR technology could be the more valuable one for the clinical application.1. For the normal cases1.1 The efficacy of the MPR and VR technologies are superior to the SSD-based CTVE one for the demonstration of the ossicular chain.1.2 By comparison, the efficacy of the MPR and VR technology showed no significant differences, however, the VR images are the real 3D ones, which should be more applied for the clinic.2. For the patients with otitis media2.1 All the three modalities could demonstrate the destruction of the ossicular chain if the threshold was set appropriately.2.2 The efficacy of MPR technology and that of VR technology were both high and showed no significant differences in assessing the malleus and incus.2.3 All the three modalities showed some limitation for the representation of the stapes.2.4 The VR technology was a promising one among these three modalities.