Combined application of single-energy metal artifact reduction and reconstruction techniques in patients with Cochlear implants

Abstract

Background The purpose of this study was to develop an effective method of reducing metal artifacts in cochlear implant (CI) electrodes. Methods The temporal bones of 30 patients (34 ears) after CI were examined with 320-detector row computed tomography, which was evaluated by two senior radiologists using a double-blind method. Noise, artifact index, signal-to-noise ratio, and the subjective image quality score were compared before versus after using single-energy metal artifact reduction (SEMAR). The electrode position, single electrode visibility, and electrode count were evaluated using SEMAR combined with either multi-planar reconstruction (MPR) or maximum intensity projection. Results The two radiologists’ measurements had good consistency. SEMAR significantly reduced the image noise and artifacts index and significantly improved the signal-to-noise ratio and subjective image quality score (P < 0.01). The combination of SEMAR with MPR was conducive to accurate assessment of electrode position and single-electrode visibility. The combination of SEMAR with MIP facilitated accurate and intuitive matching of the assessed electrode count with the number of electrodes implanted during the operation (P = 0.062). Conclusion SEMAR significantly reduces metal artifacts generated by CI electrodes and improves the quality of computed tomography images. The combination of SEMAR with MPR and maximum intensity projection is beneficial for evaluating the position and number of CI electrodes.

Improved cochlear implant electrode localization using coregistration of pre‐ and postoperative CT

“…7 However, their method used for coregistration of the pre-and postoperative images was unique from the method used in our study. specifically, Skinner et al An additional option for metallic artifact reduction reported in the literature is the combined application of single energy metal artifact reduction and reconstruction techniques in patients with CIs that was shown to be conducive to accurate localization by Wei et al 18 The methods described in the article for this technique included adjusting the scan range according to the localization image to include the range of the entire CI. In a separate scanning mode, one layer was swept within the scanning range, and two regions of interest were set inside.…”

“…An additional option for metallic artifact reduction reported in the literature is the combined application of single energy metal artifact reduction and reconstruction techniques in patients with CIs that was shown to be conducive to accurate localization by Wei et al 18 . The methods described in the article for this technique included adjusting the scan range according to the localization image to include the range of the entire CI.…”

Influence of field of view size and reconstruction methods on single-energy metal artifact reduction: a phantom study

“…AI is de ned not by the ratio of SDs in the metal artifact image and the background image, but by the difference between those of SDs [7][8][9][10]13]. Therefore, CT images with high image noise increase the difference between the SDs of the metal artifact image and the SDs of the background image.…”

“…The cause of metal artifacts are beamhardening, extensive photon starvation, and scatter [2]. Various methods are used to reduce metal artifacts, including alteration of image reconstruction method [3], scanning with a dual-energy CT [4,5], and using metal artifact reduction software [1,3,[5][6][7][8][9][10][11].…”

“…On the other hand, it has been reported that SEMAR has a different metal artifact reduction effect depending on the shape of the metal [6], image reconstruction methods [9], and the scan parameters [3,7,10]. Andersson et al [5] have indicated that the creation of new artifacts are particularly obvious when the SEMAR algorithm is combined with iterative reconstruction (IR).…”