Intracochlear assessment of electrode position after cochlear implant surgery by means of multislice computer tomography

Abstract

The development of electrode arrays, the past years, has focused on modiolus-hugging cochlear implant electrodes. Besides, atraumatic implantation of electrodes is of importance for the use in hearing preservation, in cases of combined electric and acoustic stimulation. Intracochlear positioning of the individual electrodes by means of multislice computer tomography (CT) has not yet been shown. In this study we formulated and tested a CT imaging protocol for postoperative scanning of the temporal bone in cochlear implant subjects. Both a fresh human temporal bone and a fresh human cadaver head were implanted with a cochlear implant. Multislice CT was performed for adequate depiction of the cochlear implant. All scans were analyzed on a viewing workstation. After mid-modiolar reconstruction we were able to identify the intracochlear electrode position relative to the scala tympani and scala vestibuli. This was possible in both the implanted isolated temporal bone and the fresh human cadaver head. The feasibility of imaging the electrode position of the cochlear implant within the intracochlear spaces is shown with multislice CT. An imaging protocol is suggested.

Artifacts of the electrode in cochlea implantation and limits in analysis of deep insertion in cone beam tomography (CBT)

“…Until now the focus for in vivo imaging was in CT scans and multi-slice-CT scans. DiVerent authors demonstrated the possibilities of these techniques [8,[14][15][16]. The fact that these techniques are possible for diVerent electrodes in the basal turn of the cochlea could be shown by Todt and co-workers [17].…”

Flat-panel computed tomography versus multislice computed tomography to evaluate cochlear implant positioning

“…While the utility of the plain cochlear view roentgenogram has been shown to be useful, CT has become the radiographic gold standard in addressing specific questions after CI such as localization of the electrode relative to cochlear spaces, visualization of intracochlear trauma, and the EMI as well as proximity to the Fallopian canal (Bartling et al, 2006). With the introduction of improved tomographic resolution devices such as the msCT, superior intracochlear visualization of the electrode array is now possible (Skinner et al, 2002;Aschendorff et al, 2004;Van Wermeskerken et al, 2007;Verbist et al, 2005).…”

“…With the introduction of the helical or spiral CT and subsequently the 64-slice CT scanner (multislice CT, msCT) the improved quality of the diagnostic image and an improved spatial resolution as well as a decrease in scanning time and subsequent motion artifact has led to superior intracochlear visualization of the electrode array (Skinner et al, 2002;Aschendorff et al, 2004;Van Wermeskerken et al, 2007;Verbist et al, 2005). More specifically, over the past several years, various authors have started experimenting with post-implantation radiographic measurements of the EMI as well as analysis of individual electrode contact positioning along the cochlear partition in order to correlate these variables with specific threshold and outcome measures (Saunders et al, 2002;Filipo et al, 2008;Marrinan et al, 2004).…”

MR Imaging of the Cochlear Modiolus after Intratympanic Administration of Gd-DTPA

“…13 The cochear modiolus is also a target structure for future cell replacement therapy of the inner ear. 14,15 To our knowledge, ours is theˆrst report evaluating enhancement of the cochlear modiolus by diagnostic imaging.…”