Then, midmodiolar sections were obtained with radial reconstructions through the center of the cochlea ( Fig 1). With use of axial acquisition, windmill artifacts due to presence of the cochlear implant were averted.ДЇirst, oblique multiplanar reconstructions were obtained through the cochlea, parallel to the basal turn of the cochlea. The scanning parameters were chosen such that image noise-which inherently increases with higher spatial resolution-was ameliorated and artifacts were reduced.

Images were reconstructed with filtered back projection in bone kernel (FC81) from images with a 0.25-mm section thickness with every 0.125 mm overlapping, and a field of view of 90 mm with a 1024 Г— 1024 matrix, resulting in a pixel spacing of 0.09 mm and a voxel size of 0.09 Г— 0.09 Г— 0.25 mm. cm, resulting in an effective dose of 0.25 mSv (k factor, 0.0021).The scanning parameters were as follows: 140 kV, 100 mA, rotation time of 1.5 msec, volume CT dose index of 29.9 mGy, and dose-length product of 119.6 mGy Scans were acquired in sequential scanning mode with a collimation of 160 Г— 0.25 mm, resulting in a scan range of 4 cm. UHSR CT was used to evaluate the presence of NBF. The secondary objective was to investigate the association between NBF and two clinical parameters: (a) surgical factors (ie, insertion location, electrode type, and intracochlear scalar position) and (b) long-term residual hearing loss.ДЄll participants underwent UHSR CT (Aquilion Precision, Canon Medical Systems) at the SVOE. The primary objective of this study was to describe the amount and location of NBF in a cohort of patients with cochlear implant and to test the reliability of detecting NBF using UHSR CT. UHSR CT was used to evaluate intracochlear electrode location, revealing the presence of bone densities alongside the cochlear implant electrode contacts ( 20). The UHSR CT system has various focal spot sizes, the smallest being of nominal size 0.4 Г— 0.5 mm 2 ( 19), whereas the smallest focus size in standard multidetector CT is 0.8 Г— 0.9 mm 2.

Recently, ultra-high-spatial-resolution (UHSR) CT, with 0.25-mm detector elements and matrix size up to 2048, was introduced, showing better delineation of the fine anatomic temporal bone structures than conventional multidetector CT, which has detector elements of 0.5 mm or larger and a matrix size of 512 ( 17, 18). Therefore, it seems desirable to control and reduce NBF, but this requires a method to detect and monitor NBF in vivo. Last, the presence of NBF may complicate future therapies or repeat implantation. Second, new tissue formation has been theorized to cause long-term residual acoustic hearing loss due to stiffening of the round window membrane and damping of the scala tympani ( 3). Furthermore, the spread of electrical current within the cochlea is affected, leading to complex device fitting, channel interaction, and poorer worse overall hearing outcome ( 16). At the electrode contact level, the electrical вЂњimpedanceвЂќ is increased, resulting in higher power consumption and more out-of-compliance issues ( 14вЂ“ 16). First, NBF alters the intracochlear electrophysiology. The presence of NBF around the cochlear implant electrode is relevant for several reasons. However, in vivo detection of NBF has not yet been described. This new bone formation (NBF) has been observed in animal and histopathologic studies ( 5, 6, 9вЂ“ 13). In its most pronounced form, the fibrosis can progress to neo-ossification. Second, a delayed inflammatory reaction due to the natural host tissue response can lead to encapsulation of the array in a fibrous sheath ( 7, 8). First, insertional trauma can induce an acute intracochlear tissue response, resulting in formation of iatrogenic scar tissue around the array ( 4вЂ“ 6). However, long-term changes within the cochlea caused by introducing a foreign body are neither treated nor prevented in current practice ( 3).ДЄlthough cochlear implant electrode arrays are commonly made from biocompatible polymers, they can elicit an inflammatory response in two ways. By using soft-surgery techniques (eg, low drill speeds and slow insertion), the extent of insertional trauma can be reduced ( 1, 2). Today, even patients with functional residual hearing may receive a cochlear implant. A cochlear implant is a neuroprosthetic device that forms an effective solution for patients with severe-to-profound hearing loss.

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