The Value Of Multi-planner Reformation And Three-dimensional Volume Rendering In The Diagnosis Of The Congenital Deformity Of The Middle Ear

Preface and background:The incidence of congenital middle ear malformation is about 1/11000-15000,it is not easy to diagnose.At present,tymponoplasty is still considerate as a gold standard in the diagnosis of congenital malformation of the middle ear.Preoperative imaging is very important.How to accurately evaluate the middle ear malformation before operation,which is of great significance to the planning of operation and the improvement of hearing after operation.Auditory ossicles are unable to clearly display by traditional multi-slice spiral CT(MSCT).High-Spatial resolution computer tomography(HSRCT)of the temporal bone is suitable for us to define the ossicles,but it is difficult to clearly show the details of the ossicles,specially,the head of stapes,the lenticular process of the incus,the incudo-stapedial joint and so on.With the development of multi-planner reformation(MPR)and three-dimensional volume rendering(3DVR),which present better diagnostic capability of the middle ear malformation,some studies have been carried out in this erea.ObjectiveBy HRCT +MPR/3DVR in patients with simple middle ear malformations,we try to analyse the fine structure of the middle ear,especially various parts of ossicular chain.The aim of the study is to explore the diagnostic value of MPR/3DVR in the middle ear malformations combined with the results of surgical findings,the application value of the processing technologies,and its guiding significance for surgery.Methods51 patients with conductive hearing loss were enrolled in the 1st Affiliated Hospital of Zhejiang University from Feb.2015 and Nov.2018.The ages of the patients ranged from 9 to 52 years(24±11 years old),32 males and 19 females among these.There were no definite reasons for the patients with non-progressive,unilateral or bilateral conductive hearing loss.High resolution CT of the temporal bone was performed.Scans were then transmitted to ADW4.5(GE)workstation where MPR and 3 DVR image data was processed.At last,18 cases(19 ears)of these choose to do the tympanoplasty.We try to compare the imaging results of MPR and 3DVR with the surgical findings,to evaluate the accuracy of the middle ear malformation.and to show the diagnostic value of 12 sub-structures of the ossicular chain.ResultsAmong 18 cases(19 ears)of congenital simple middle ear deformity,no malleus malformation was found,while the rate of malformation in incus、stapes、oval window and facial nerve was 10/19、14/19、3/19 and 7/19,respectively.MPR and 3DVR showed equally very high diagnostic accuracy in the diagnosis of the head、neck、manubrium and lateral process of the malleus、the body、long process and short process of incus and incudomalleolar joint.Both of 3DVR and MPR show good capability of demonstrating the lenticular process of incus,3DVR is better than MPR.For the revealing of the stapes,MPR is good at showing the anterior and posterior crus of stapes,while 3 DVR sometimes reveals them incompletely or vaguely;3DVR is extremely poor at displaying the footplate of stapes,while MPR shows a better view;therefore,the value of MPR was relative higher than 3DVR in the diagnosis of congenital simple middle ear malformations.The preoperative accuracy rate of incus deformity was 100%based on MPR and 3DVR(9/10 by MPR and 10/10 by 3DVR,respectively).Due to the shortcomings of 3DVR technology,the diagnostic accuracy of the stapes was mainly dependent on MPR,which was 71.43%.The vestibular window deformity was also comfined by MPR,which was 3/3.However,it was not easy to evaluate the malformation of the facial nerve before operation,the accuracy rate of was 3/7.ConclusionMPR and 3DVR are good choices for preoperative diagnosis of congenital ossicular chain deformity.For the 14 substructures of the ossicular chain,MPR has higher diagnostic accuracy.The diagnosis accuracy of the incus deformity almost achieved 100%based on MPR and 3DVR.The precise evaluate of stapes deformity and vestibular window deformity mainly depended on MPR,while the preoperative diagnosis rate of facial nerve deformity was relatively low.