Cochlear Implantation: Systematic Approach to Preoperative Radiologic                     Evaluation

Background We evaluated the accuracy of magnetic resonance imaging (MRI) computed tomography (CT)-like sequences compared to normal-resolution CT (NR-CT) and super-high-resolution CT (SHR-CT) for planning of cochlear implantation. Methods Six cadaveric temporal bone specimens were used. 3-T MRI scans were performed using radial volumetric interpolated breath-hold (STARVIBE), pointwise-encoding time reduction with radial acquisition (PETRA), and ultrashort time of echo (UTE) sequences. CT scans were performed on two scanners for SHR-CT and NR-CT acquisitions. Two radiologists evaluated accuracy based on preimplantation metrics and the ability to identify various anatomical structures, particularly the facial recess and round window. Wilcoxon rank-sum test and intraclass correlation coefficient (ICC) were used. Results The facial nerve was always clearly visible (score ≥ 2) in the MRI, NR-CT, and SHR-CT scans (p ≥ 0.621). However, the chorda tympani nerve (CTN) was clearly visualized in UTE, STARVIBE, and PETRA sequences in only 33% (2/6 specimens, p = 0.016), 50% (3/6 specimens, p = 0.038), and 83% (5/6 specimens, p = 0.017) of cases, respectively, whereas it was always clearly visualized in SHR and NR-CT (p = 0.426). The round window (RW) was never visualized in MRI sequences (p ≤ 0.010), whereas it was identified in all cases in SHR and NR-CT (p = 1.000). There was a strong correlation between measurements obtained from MRI and CT modalities (ICC ≥ 0.837). Conclusion MRI CT-like sequences assessed the facial nerve in all cases and the CTN in up to 87% of cases. However, the detection of the RW was insufficient for surgical planning. CT and MRI measurements were in agreement. Relevance statement CT-like MRI sequences can image the anatomy of the facial recess and the length of the basal turn of the cochlea with similar accuracy as conventional CT, although they cannot image the round window. Key Points CT-like MRI sequences are not widely used in preoperative cochlear implantation imaging. CT-like sequences can image the facial recess as well as conventional CT. CT-like sequences can image the basal turn length of the cochlea as well as conventional CT. Round window depiction is not possible with CT-like MRI sequences. Graphical Abstract

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Dynamic micro-optical coherence tomography enables structural and metabolic imaging of the mammalian cochlea

Schulz-Hildebrandt,

Spasic,

Hou

et al. 2024

Front. Mol. Neurosci.

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Sensorineural hearing loss (SNHL) is caused by damage to the mechanosensory hair cells and auditory neurons of the cochlea. The development of imaging tools that can directly visualize or provide functional information about a patient’s cochlear cells is critical to identify the pathobiological defect and determine the cells’ receptiveness to emerging SNHL treatments. However, the cochlea’s small size, embedded location within dense bone, and sensitivity to perturbation have historically precluded high-resolution clinical imaging. Previously, we developed micro-optical coherence tomography (μOCT) as a platform for otologic imaging in animal models and human cochleae. Here we report on advancing μOCT technology to obtain simultaneously acquired and co-localized images of cell viability/metabolic activity through dynamic μOCT (DμOCT) imaging of intracellular motion. DμOCT obtains cross-sectional images of ATP-dependent movement of intracellular organelles and cytoskeletal polymerization by acquiring sequential μOCT images and computing intensity fluctuation frequency metrics on a pixel-wise basis. Using a customized benchtop DμOCT system, we demonstrate the detailed resolution of anatomical and metabolic features of cells within the organ of Corti, via an apical cochleostomy, in freshly-excised adult mouse cochleae. Further, we show that DμOCT is capable of capturing rapid changes in cochlear cell metabolism following an ototoxic insult to induce cell death and actin stabilization. Notably, as few as 6 frames can be used to reconstruct cochlear DμOCT images with sufficient detail to discern individual cells and their metabolic state. Taken together, these results motivate future development of a DμOCT imaging probe for cellular and metabolic diagnosis of SNHL in humans.

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Cochlear Implantation: Systematic Approach to Preoperative Radiologic Evaluation

Cited by 5 publications

References 66 publications

Evaluation of Hearing Loss: Understanding Audiologic Testing to Refine Image Interpretation

Evaluation of Hearing Loss: Understanding Audiologic Testing to Refine Image Interpretation

Comparison of CT-like MRI sequences for preoperative planning of cochlear implantation using super-high-resolution CT as a reference

Dynamic micro-optical coherence tomography enables structural and metabolic imaging of the mammalian cochlea

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