Comparación Multi-Lector de Reconstrucciones CT de Detector de Conteo de Fotones para la Evaluación de Implantes...

Photon-counting CT (PCCT) offers several advantages over conventional CT for cochlear implant (CI) imaging, including improved spatial resolution, and both signal-to-noise and contrast-to-noise ratios. However, the optimal PCCT reconstruction parameters for CI imaging has not been established. This study compared six PCCT reconstruction approaches for temporal bone CI imaging in a multi-reader design.

20 patients with CIs (24 implants) underwent temporal bone PCCT on a NAEOTOM Alpha scanner. Raw data was reconstructed using six different algorithms, as follows: Hr84 0.2mm T3D (head-regular, sharpness level 84, polyenergetic), Hr84 0.4mm T3D, Qr56 0.4mm iMAR T3D (quantitative-regular, sharpness level 56, iterative metal artifact reduction), Qr76 0.4mm M_140 (virtual monoenergetic 140 keV), Qr76 0.4mm M_70 (virtual monoenergetic 70 keV), and Qr76 0.4mm T3D.Two fellowship-trained neuroradiologists independently rated electrode visibility and overall image quality for all implants, and wire visibility for implants with visible wires, on 0-2 Likert scales. Inter-reader agreement was assessed with quadratic weighted Cohen's kappa. A mixed effects model was used to evaluate reconstruction differences for each metric.

Mean patient age was 50.9 ± 26 years; 8 were women. Inter-reader agreement was substantial for electrode visibility (κ = 0.66) and overall image quality (κ = 0.79), and moderate for wire visibility (κ = 0.52). Reconstruction type significantly affected all three metrics. The sharp kernel reconstructions (Hr84 0.2mm T3D and Hr84 0.4mm T3D) consistently ranked highest, with significantly greater scores than most other reconstructions. Qr56 0.4mm iMAR T3D was the lowest rated in every category, significantly worse than all other reconstructions.

PCCT reconstruction parameters substantially influence postoperative CI image quality. Ultra-high-resolution reconstructions provided the best combination of artifact suppression and fine structural detail, while iterative MAR and high-keV monoenergetic reconstructions performed the worst. These findings can guide reconstruction selection to optimize PCCT protocols for CI evaluation.