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Walia A, Shew MA, Varghese J, Lefler SM, Bhat A, Ortmann AJ, Herzog JA, Buchman CA. Electrocochleography-Based Tonotopic Map: II. Frequency-to-Place Mismatch Impacts Speech-Perception Outcomes in Cochlear Implant Recipients. Ear Hear 2024:00003446-990000000-00298. [PMID: 38880958 DOI: 10.1097/aud.0000000000001528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
OBJECTIVES Modern cochlear implants (CIs) use varying-length electrode arrays inserted at varying insertion angles within variably sized cochleae. Thus, there exists an opportunity to enhance CI performance, particularly in postlinguistic adults, by optimizing the frequency-to-place allocation for electrical stimulation, thereby minimizing the need for central adaptation and plasticity. There has been interest in applying Greenwood or Stakhovskaya et al. function (describing the tonotopic map) to postoperative imaging of electrodes to improve frequency allocation and place coding. Acoustically-evoked electrocochleography (ECochG) allows for electrophysiologic best-frequency (BF) determination of CI electrodes and the potential for creating a personalized frequency allocation function. The objective of this study was to investigate the correlation between early speech-perception performance and frequency-to-place mismatch. DESIGN This retrospective study included 50 patients who received a slim perimodiolar electrode array. Following electrode insertion, five acoustic pure-tone stimuli ranging from 0.25 to 2 kHz were presented, and electrophysiological measurements were collected across all 22 electrode contacts. Cochlear microphonic tuning curves were subsequently generated for each stimulus frequency to ascertain the BF electrode or the location corresponding to the maximum response amplitude. Subsequently, we calculated the difference between the stimulus frequency and the patient's CI map's actual frequency allocation at each BF electrode, reflecting the frequency-to-place mismatch. BF electrocochleography-total response (BF-ECochG-TR), a measure of cochlear health, was also evaluated for each subject to control for the known impact of this measure on performance. RESULTS Our findings showed a moderate correlation (r = 0.51; 95% confidence interval: 0.23 to 0.76) between the cumulative frequency-to-place mismatch, as determined using the ECochG-derived BF map (utilizing 500, 1000, and 2000 Hz), and 3-month performance on consonant-nucleus-consonant words (N = 38). Larger positive mismatches, shifted basal from the BF map, led to enhanced speech perception. Incorporating BF-ECochG-TR, total mismatch, and their interaction in a multivariate model explained 62% of the variance in consonant-nucleus-consonant word scores at 3 months. BF-ECochG-TR as a standalone predictor tended to overestimate performance for subjects with larger negative total mismatches and underestimated the performance for those with larger positive total mismatches. Neither cochlear diameter, number of cochlear turns, nor apical insertion angle accounted for the variability in total mismatch. CONCLUSIONS Comparison of ECochG-BF derived tonotopic electrode maps to the frequency allocation tables reveals substantial mismatch, explaining 26.0% of the variability in CI performance in quiet. Closer examination of the mismatch shows that basally shifted maps at high frequencies demonstrate superior performance at 3 months compared with those with apically shifted maps (toward Greenwood and Stakhovskaya et al.). The implications of these results suggest that electrophysiological-based frequency reallocation might lead to enhanced speech-perception performance, especially when compared with conventional manufacturer maps or anatomic-based mapping strategies. Future research, exploring the prospective use of ECochG-based mapping techniques for frequency allocation is underway.
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Affiliation(s)
- Amit Walia
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine in St. Louis, St Louis, Missouri, USA
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Rajagopal JR, Schwartz FR, Solomon JB, Enterline DS, Samei E. High Spatial-Resolution Skull Base Imaging With Photon-Counting Computed Tomography and Energy-Integrating Computed Tomography: A Comparative Phantom Study. J Comput Assist Tomogr 2023; 47:613-620. [PMID: 37380149 PMCID: PMC10356746 DOI: 10.1097/rct.0000000000001464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
Abstract
ABSTRACT Photon-counting computed tomography (PCCT) offers better high-resolution and noise performance than energy integrating detector (EID) CT. In this work, we compared both technologies for imaging of the temporal bone and skull base. A clinical PCCT system and 3 clinical EID CT scanners were used to image the American College of Radiology image quality phantom using a clinical imaging protocol with matched CTDI vol (CT dose index-volume) of 25 mGy. Images were used to characterize the image quality of each system across a series of high-resolution reconstruction options. Noise was calculated from the noise power spectrum, whereas resolution was quantified with a bone insert by calculating a task transfer function. Images of an anthropomorphic skull phantom and 2 patient cases were examined for visualization of small anatomical structures. Across measured conditions, PCCT had a comparable or smaller average noise magnitude (120 Hounsfield units [HU]) to the EID systems (144-326 HU). Photon-counting CT also had comparable resolution (task transfer function f25 : 1.60 mm -1 ) to the EID systems (1.34-1.77 mm -1 ). Imaging results supported quantitative findings as PCCT more clearly showed the 12-lp/cm bars from the fourth section of the American College of Radiology phantom and better represented the vestibular aqueduct and oval and round windows when compared with the EID scanners. A clinical PCCT system was able to image the temporal bone and skull base with improved spatial resolution and lower noise than clinical EID CT systems at matched dose.
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Affiliation(s)
- Jayasai R. Rajagopal
- Carl E. Ravin Advanced Imaging Laboratories, Medical Physics Graduate Program, Department of Radiology, Duke University Medical Center, Durham, NC 27705
- Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD 20892
| | - Fides R. Schwartz
- Duke University Health System, Department of Radiology, Duke University Medical Center, Durham, NC 27705
| | - Justin B. Solomon
- Carl E. Ravin Advanced Imaging Laboratories, Medical Physics Graduate Program, Department of Radiology, Duke University Medical Center, Durham, NC 27705
| | - David S. Enterline
- Duke University Health System, Department of Radiology, Duke University Medical Center, Durham, NC 27705
| | - Ehsan Samei
- Carl E. Ravin Advanced Imaging Laboratories, Medical Physics Graduate Program, Department of Radiology, Duke University Medical Center, Durham, NC 27705
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[Measuring the cochlea using a tablet-based software package: influence of imaging modality and rater background]. HNO 2022; 70:769-777. [PMID: 35970933 PMCID: PMC9512738 DOI: 10.1007/s00106-022-01208-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/20/2022] [Indexed: 11/04/2022]
Abstract
BACKGROUND Cochlear duct length (CDL) is subject to significant individual variation. In the context of cochlear implantation, adapting the electrode array length to the CDL is of potential interest, as it has been associated with improvements in both speech recognition and sound quality. Using a tablet-based software package, it is possible to measure CDL at the level of the organ of Corti (CDLOC) to select appropriate electrode array lengths based on individual cochlear anatomy. OBJECTIVE To identify effects of imaging modality and rater background on CDL estimates. METHODS Magnetic resonance imaging (MRI) and flat-panel volume CT (fpVCT) scans of 10 patients (20 cochleae) were analyzed using the OTOPLAN software package (MED-EL, Innsbruck, Austria). Raters were an otorhinolaryngology (ORL) specialist, an ORL resident, and an audiologist. To analyze effects of rater background and imaging modality on CDL measurements, linear mixed models were constructed. RESULTS Measurements showed mean CDLOC(fpVCT) = 36.69 ± 1.78 mm and CDLOC(MRI) = 36.81 ± 1.87 mm. Analyses indicated no significant effect of rater background (F(2, 105) = 0.84; p = 0.437) on CDL estimates. Imaging modality, on the other hand, significantly affected CDL (F (1, 105) = 20.70; p < 0.001), whereby estimates obtained using MRI were 0.89 mm larger than those obtained using fpVCT. CONCLUSION No effect of rater background on CDL estimates could be identified, suggesting that comparable measurements could be obtained by personnel other than specially trained neurootologists. While imaging modality (fpVCT vs. MRI) did impact CDL results, the difference was small and of questionable clinical significance.
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Fahrig R, Jaffray DA, Sechopoulos I, Webster Stayman J. Flat-panel conebeam CT in the clinic: history and current state. J Med Imaging (Bellingham) 2021; 8:052115. [PMID: 34722795 DOI: 10.1117/1.jmi.8.5.052115] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 09/27/2021] [Indexed: 11/14/2022] Open
Abstract
Research into conebeam CT concepts began as soon as the first clinical single-slice CT scanner was conceived. Early implementations of conebeam CT in the 1980s focused on high-contrast applications where concurrent high resolution ( < 200 μ m ), for visualization of small contrast-filled vessels, bones, or teeth, was an imaging requirement that could not be met by the contemporaneous CT scanners. However, the use of nonlinear imagers, e.g., x-ray image intensifiers, limited the clinical utility of the earliest diagnostic conebeam CT systems. The development of consumer-electronics large-area displays provided a technical foundation that was leveraged in the 1990s to first produce large-area digital x-ray detectors for use in radiography and then compact flat panels suitable for high-resolution and high-frame-rate conebeam CT. In this review, we show the concurrent evolution of digital flat panel (DFP) technology and clinical conebeam CT. We give a brief summary of conebeam CT reconstruction, followed by a brief review of the correction approaches for DFP-specific artifacts. The historical development and current status of flat-panel conebeam CT in four clinical areas-breast, fixed C-arm, image-guided radiation therapy, and extremity/head-is presented. Advances in DFP technology over the past two decades have led to improved visualization of high-contrast, high-resolution clinical tasks, and image quality now approaches the soft-tissue contrast resolution that is the standard in clinical CT. Future technical developments in DFPs will enable an even broader range of clinical applications; research in the arena of flat-panel CT shows no signs of slowing down.
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Affiliation(s)
- Rebecca Fahrig
- Innovation, Advanced Therapies, Siemens Healthcare GmbH, Forchheim, Germany.,Friedrich-Alexander Universitat, Department of Computer Science 5, Erlangen, Germany
| | - David A Jaffray
- MD Anderson Cancer Center, Departments of Radiation Physics and Imaging Physics, Houston, Texas, United States
| | - Ioannis Sechopoulos
- Radboud University Medical Center, Department of Medical Imaging, Nijmegen, The Netherlands.,Dutch Expert Center for Screening (LRCB), Nijmegen, The Netherlands.,University of Twente, Technical Medical Center, Enschede, The Netherlands
| | - J Webster Stayman
- Johns Hopkins University, Department of Biomedical Engineering, Baltimore, Maryland, United States
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Lo Russo F, Conte G, Di Berardino F, Cavicchiolo S, Casale S, Caschera L, Lombardi L, Triulzi F, Zanetti D. Impact of Cochlear Implant Array Placement on Speech Perception. Clin Neuroradiol 2021; 32:175-183. [PMID: 34142163 DOI: 10.1007/s00062-021-01046-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 05/17/2021] [Indexed: 11/29/2022]
Abstract
PURPOSE To assess the role of flat panel computed tomography (FPCT) in the evaluation of cochlear implant (CI) electrode position and its relation to speech perception. METHODS From March 2015 to March 2019, we retrospectively enrolled deaf subjects ≥ 18 years who underwent unilateral CI by one surgeon, imaged with FPCT and assessed with disyllabic words score before CI and at 6 months of follow-up. We calculated the disyllabic score difference before CI and after CI (ΔSDS) and divided the subjects in favorable and unfavorable outcome groups using the median ΔSDS as a cutoff. We compared the demographic, clinical, electrode characteristics, and the CI positioning variables scalar position, surgical insertion depth (SID), linear insertion depth (LID), angular insertion depth (AID) and wrapping factor (WF). RESULTS We studied 50 subjects (F/M = 27/23; median age = 60.5 years, IQR: 50-70 years). The median ΔSDS was 80% (interquartile range [IQR]: 60-100%) in quiet and 80% (IQR: 47.5-100%) in noise. Of the subjects 23 demonstrated a favorable outcome and had earlier age at CI (median 52 years; IQR 45-67 years versus median 62 years; IQR: 56-71 years p = 0.032) and a significantly higher SID (median: 4.02 mm IQR: 3.00-5.35 mm versus median: 2.94 mm IQR: 2.06-3.90 mm; p = 0.029). No difference was found for LID (p = 0.977), AID (p = 0.302), and WF (p = 0.224). A logistic regression model built with the age at CI, number of CI electrodes, and the SID was significant χ2 ((df = 3, N = 50) = 14.517, p = 0.002). The model explained 33.7% (Nagelkerke R2) of ΔSDS variance and correctly classified 76% of the cases. CONCLUSION The SID measured by FPCT predicts the ΔSDS at 6 months follow-up, alongside with age at implantation and number of CI electrodes.
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Affiliation(s)
- Francesco Lo Russo
- Department of Neuroradiology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, via Francesco Sforza, 28, 20122, Milan, Italy.
| | - Giorgio Conte
- Department of Neuroradiology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, via Francesco Sforza, 28, 20122, Milan, Italy
| | - Federica Di Berardino
- Audiology Unit, Department of Clinical Sciences and Community Health, Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy
| | - Sara Cavicchiolo
- Audiology Unit, Department of Clinical Sciences and Community Health, Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy
| | - Silvia Casale
- Department of Neuroradiology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, via Francesco Sforza, 28, 20122, Milan, Italy
| | - Luca Caschera
- Department of Neuroradiology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, via Francesco Sforza, 28, 20122, Milan, Italy
| | - Luciano Lombardi
- Department of Neuroradiology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, via Francesco Sforza, 28, 20122, Milan, Italy
| | - Fabio Triulzi
- Department of Neuroradiology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, via Francesco Sforza, 28, 20122, Milan, Italy.,Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy
| | - Diego Zanetti
- Audiology Unit, Department of Clinical Sciences and Community Health, Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy
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Hedjoudje A, Schoo DP, Ward BK, Carey JP, Della Santina CC, Pearl M. Vestibular Implant Imaging. AJNR Am J Neuroradiol 2021; 42:370-376. [PMID: 33361382 PMCID: PMC7872165 DOI: 10.3174/ajnr.a6991] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 09/10/2020] [Indexed: 11/07/2022]
Abstract
Analogous to hearing restoration via cochlear implants, vestibular function could be restored via vestibular implants that electrically stimulate vestibular nerve branches to encode head motion. This study presents the technical feasibility and first imaging results of CT for vestibular implants in 8 participants of the first-in-human Multichannel Vestibular Implant Early Feasibility Study. Imaging characteristics of 8 participants (3 men, 5 women; median age, 59.5 years; range, 51-66 years) implanted with a Multichannel Vestibular Implant System who underwent a postimplantation multislice CT (n = 2) or flat panel CT (n = 6) are reported. The device comprises 9 platinum electrodes inserted into the ampullae of the 3 semicircular canals and 1 reference electrode inserted in the common crus. Electrode insertion site, positions, length and angle of insertion, and number of artifacts were assessed. Individual electrode contacts were barely discernible in the 2 participants imaged using multislice CT. Electrode and osseous structures were detectable but blurred so that only 12 of the 18 stimulating electrode contacts could be individually identified. Flat panel CT could identify all 10 electrode contacts in all 6 participants. The median reference electrode insertion depth angle was 9° (range, -57.5° to 45°), and the median reference electrode insertion length was 42 mm (range, -21-66 mm). Flat panel CT of vestibular implants produces higher-resolution images with fewer artifacts than multidetector row CT, allowing visualization of individual electrode contacts and quantification of their locations relative to vestibular semicircular canals and ampullae. As multichannel vestibular implant imaging improves, so will our understanding of the relationship between electrode placement and vestibular performance.
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Affiliation(s)
- A Hedjoudje
- From the Department of Otolaryngology-Head and Neck Surgery (A.H., D.P.S., B.K.W., J.P.C., C.C.D.S.)
- Division of Interventional Neuroradiology (A.H., M.P.)
- Neuroradiology Unit (A.H.), Service of diagnostic and interventional imaging, Sion Hospital, Sion, Valais, Switzerland
| | - D P Schoo
- From the Department of Otolaryngology-Head and Neck Surgery (A.H., D.P.S., B.K.W., J.P.C., C.C.D.S.)
| | - B K Ward
- From the Department of Otolaryngology-Head and Neck Surgery (A.H., D.P.S., B.K.W., J.P.C., C.C.D.S.)
| | - J P Carey
- From the Department of Otolaryngology-Head and Neck Surgery (A.H., D.P.S., B.K.W., J.P.C., C.C.D.S.)
| | - C C Della Santina
- From the Department of Otolaryngology-Head and Neck Surgery (A.H., D.P.S., B.K.W., J.P.C., C.C.D.S.)
- Department of Biomedical Engineering (C.C.D.S.), Johns Hopkins University School of Medicine, Baltimore, Maryland
- Labyrinth Devices (C.C.D.S.), Baltimore, Maryland
| | - M Pearl
- Division of Interventional Neuroradiology (A.H., M.P.)
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Zanetti D, Conte G, Di Berardino F, Lo Russo F, Cavicchiolo S, Triulzi F. Assessment of Frequency-Place Mismatch by Flat-Panel CT and Correlation With Cochlear Implant Performance. Otol Neurotol 2021; 42:165-173. [PMID: 33885263 DOI: 10.1097/mao.0000000000002967] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To calculate the frequency allocation mismatch in a group of very selected cochlear implant (CI) recipients and to contrast it with the speech perception performances. STUDY DESIGN Cross-sectional observational prospective study. SETTINGS Tertiary Audiological Department, University hospital. PATIENTS Fifteen adults receiving the same CI array by the same surgeon through a posterior tympanotomy, round window approach. MAIN OUTCOME MEASURES 1) High definition flat panel computed tomography (FPCT) control of the intracochlear position of each electrode contact, and computation of the relative frequency allocation mismatch; 2) analysis of speech perception outcomes in relation with the mismatch. RESULTS Despite a consistent and reproducible surgical procedure with the same intracochlear array, significant deviations from the frequency allocation tables (FAT) assigned by default by the manufacturer were observed in this study.Their influences on speech perception performances were negligible in the simple tasks of words or sentences recognition in quiet (and, to a lesser extent also in noise). The greatest effect of a significant mismatch was observed for the vocal-consonant-vocal (VCV) sequences recognition under noise masking, the emotional and the linguistic prosody recognition, and the phonemes discrimination of the Auditory Speech Sound Evaluation (A§E) test. CONCLUSIONS The greatest frequency-to-place occurred at the high frequencies. The effect was rather irrelevant on simple words and sentences recognition, while it negatively impacted on the more complex perceptual tasks.
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Affiliation(s)
- Diego Zanetti
- Audiology Unit, Department of Clinical Sciences and Community Health, University of Milan and Department of Specialistic Surgical Sciences, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Giorgio Conte
- Department of Neuroradiology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico
| | - Federica Di Berardino
- Audiology Unit, Department of Clinical Sciences and Community Health, University of Milan and Department of Specialistic Surgical Sciences, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Francesco Lo Russo
- Postgraduation School of Radiodiagnostics, Università degli Studi di Milano, Milan, Italy
| | - Sara Cavicchiolo
- Audiology Unit, Department of Clinical Sciences and Community Health, University of Milan and Department of Specialistic Surgical Sciences, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Fabio Triulzi
- Department of Neuroradiology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico
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Stock A, Bozzato V, Kloska SP, Bozzato A, Hoppe U, Hornung J, Dörfler A, Struffert T. Evaluation After Cochlear Implant Surgery : Correlation of Clinical Outcome and Imaging Findings using Flat-detector CT. Clin Neuroradiol 2020; 31:367-372. [PMID: 32556392 PMCID: PMC8410718 DOI: 10.1007/s00062-020-00922-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 05/27/2020] [Indexed: 11/14/2022]
Abstract
Purpose Assessment of the cochlear implant (CI) electrode array position using flat-detector computed tomography (FDCT) to test dependence of postoperative outcome on intracochlear electrode position. Methods A total of 102 patients implanted with 107 CIs underwent FDCT. Electrode position was rated as 1) scala tympani, 2) scala vestibuli, 3) scalar dislocation and 4) no deconvolution. Two independent neuroradiologists rated all image data sets twice and the scalar position was verified by a third neuroradiologist. Presurgical and postsurgical speech audiometry by the Freiburg monosyllabic test was used to evaluate auditory outcome after 6 months of speech rehabilitation. Results Electrode array position was assessed by FDCT in 107 CIs. Of the electrodes 60 were detected in the scala tympani, 21 in the scala vestibuli, 24 electrode arrays showed scalar dislocation and 2 electrodes were not placed in an intracochlear position. There was no significant difference in rehabilitation outcomes between scala tympani and scala vestibuli inserted patients. Rehabilitation was also possible in patients with dislocated electrodes. Conclusion The use of FDCT is a reliable diagnostic method to determine the position of the electrode array. In our study cohort, the electrode position had no significant impact on postoperative outcome except for non-deconvoluted electrode arrays.
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Affiliation(s)
- Annika Stock
- Department of Neuroradiology, University Hospital Erlangen-Nuremberg, Erlangen, Germany. .,Department of Neuroradiology, University Hospital Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany.
| | - Victoria Bozzato
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Saarland Medical School, Homburg, Germany
| | - Stephan P Kloska
- Department of Neuroradiology, University Hospital Erlangen-Nuremberg, Erlangen, Germany.,Department of Radiology, Hospital Fuerth, Fürth, Germany
| | - Alessandro Bozzato
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Saarland Medical School, Homburg, Germany
| | - Ulrich Hoppe
- Department of Otorhinolaryngology, Head & Neck Surgery, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Joachim Hornung
- Department of Otorhinolaryngology, Head & Neck Surgery, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Arnd Dörfler
- Department of Neuroradiology, University Hospital Erlangen-Nuremberg, Erlangen, Germany
| | - Tobias Struffert
- Department of Neuroradiology, University Hospital Erlangen-Nuremberg, Erlangen, Germany.,Department of Neuroradiology, University Hospital Gießen, Gießen, Germany
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Flat Panel Computed Tomography in the Diagnosis of Superior Semicircular Canal Dehiscence Syndrome. Otol Neurotol 2020; 40:213-217. [PMID: 30570605 DOI: 10.1097/mao.0000000000002076] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS Flat panel computed tomography (FPCT) provides more accurate measurements of dimensions for superior semicircular canal dehiscence (SCD) than multislice CT (MSCT). BACKGROUND SCD syndrome occurs when a bony defect of the superior semicircular canal causes vestibular and auditory symptoms. MSCT can overestimate the size of the canal defect, with possible over-diagnosis of SCD and suboptimal selection of surgical approach. The higher resolution of FPCT should afford more accurate measurements of these defects. METHODS Radiographic and surgical measurements were compared in 22 patients (mean age 49.4) with clinical SCD syndrome and canal defects confirmed at surgery. Twenty second FPCT scans were acquired before surgery with parameters: 109Kv, small focus, 200 degrees rotation angle, and 0.4 degree per frame angulation step. Dehiscence dimensions were measured from orthogonal multiplanar reconstructions on a high-resolution liquid crystal display monitor and compared with actual measurements recorded during microsurgery. RESULTS SCD dimensions by FPCT (x) were 2.8 ± 1.6 mm for length and 0.72 ± 0.28 mm for width. The surgical measurements (y) were 2.8 ± 1.7 mm for length and 0.72 ± 0.34 mm for width. Linear fits between x and y yielded R values of 0.93 (length) and 0.66 (width). Our previous study using MSCT had R values of 0.28 (length) and 0.48 (width). The average difference between each FPCT and corresponding surgical measurement was not significantly different from zero, whereas the results for MSCT were significantly different. CONCLUSION FPCT can provide more accurate measurements of SCD than MSCT. Clinicians should consider using FPCT for imaging suspected SCD.
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Dyna-CT of the temporal bone for case-specific three-dimensional rendering of the stapedial muscle for planning of electrically evoked stapedius reflex threshold determination during cochlear implantation directly from the stapedius muscle via a retrofacial approach: a pilot study. Eur Arch Otorhinolaryngol 2020; 277:975-985. [DOI: 10.1007/s00405-019-05773-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 12/17/2019] [Indexed: 11/26/2022]
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The Image Fusion Technique for Cochlear Implant Imaging: A Study of its Application for Different Electrode Arrays. Otol Neurotol 2019; 41:e216-e222. [PMID: 31834210 DOI: 10.1097/mao.0000000000002479] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To investigate the benefits of the image fusion technique for precise postoperative assessment of intracochlear placement with six different electrode arrays. STUDY DESIGN Consecutive retrospective case study. SETTINGS Tertiary referral center. PATIENTS Analyses of imaging data of 30 patients implanted with six different electrode arrays. INTERVENTIONS Electrode reconstructions obtained from postoperative cone-beam computed tomography (CBCT) were overlaid onto preoperative magnetic resonance imaging (MRI) and/or high-resolution computed tomography (HRCT) registrations to create artefact-free images. MAIN OUTCOME MEASURES Each electrode's intracochlear position was analyzed with the image fusion reconstructions and compared with the results obtained by CBCT alone. The electrode location was classified according to its position in relation to the basal membrane at four different insertion angles. RESULTS In 40 out of 151 measurements (26.5%), the location grading obtained by CBCT alone changed after the assessment with the image fusion reconstructions. A significant association was found between deep insertions (over 360 degrees) and the effectiveness of image fusion (p = 0.019). The difference between the impact of the fusion technique for the basal turn versus the apical part was highly significant (p = 0.001). There was no significant difference between the effectiveness of the image fusion and the different electrodes. CONCLUSIONS By utilizing an image fusion technique, a more accurate assessment of electrode placement could be achieved for all types of electrodes. Image fusion was especially beneficial for insertions beyond 360 degrees.
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Reimann K, Hirt B, Schulze M. Image quality of flat-panel computed tomography using 2 different acquisition times versus multidetector computed tomography in whole-head temporal bone specimen. Eur Arch Otorhinolaryngol 2019; 277:415-422. [PMID: 31758306 DOI: 10.1007/s00405-019-05726-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 11/07/2019] [Indexed: 11/26/2022]
Abstract
PURPOSE Imaging of temporal bone and skull base acquire high resolution due to the small anatomic structures with high clinical relevance. The purpose of this study was to compare image quality of the temporal bone in standard 20 s protocol flat-panel computed tomography (FPCT) with the new time- and dose improved 10 s protocol as well as with 128 slice multidetector computed tomography (MDCT). The aim was to evaluate the new time- and dose improved 10 s protocol. METHODS 10 whole-skull preparations-20 temporal bones-were scanned with either 128 slice MDCT CT (SOMATOM Definition AS + , Siemens, Erlangen) or FPCT (AXIOM-Artis, Siemens, Erlangen) using 10 s or 20 s protocol. RESULTS We show here that overall FPCT provides significantly better image quality and improved delimitation of clinically relevant structures in the temporal bone compared to 128 slice MDCT. Especially the shorter, dose saving 10 s protocol of the FPCT is still superior to 128 slice MDCT. The 20 s FPCT protocol was only significantly superior in identification of the cochlear apical turn and can thereby be used specifically in clinical cases with pathologies in this area. CONCLUSIONS The 10 s FPCT protocol yields a significantly better image quality than MDCT in imaging finer structures of the temporal bone.
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Affiliation(s)
- Katrin Reimann
- Department of Otorhinolaryngology, Head and Neck Surgery, Eberhard Karls University, Tübingen, Elfriede-Aulhorn-Strasse 5, 72076, Tübingen, Germany.
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital of Marburg, Philipps-Universität Marburg, Baldingerstrasse, 35043, Marburg, Germany.
| | - Bernhard Hirt
- Institute of Clinical Anatomy and Cell Analysis, Eberhard Karls University, Tübingen, Elfriede-Aulhorn-Straße 8, 72076, Tübingen, Germany
| | - Maximilian Schulze
- Department of Neuroradiology, Eberhard Karls University, Tübingen, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany
- Department of Neuroradiology, University Hospital Marburg, Philipps-Universität Marburg, Baldingerstrasse, 35043, Marburg, Germany
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Reducing Radiation Dose for High-resolution Flat-panel CT Imaging of Superior Semicircular Canal Dehiscence. Otol Neurotol 2019; 39:e683-e690. [PMID: 30113564 DOI: 10.1097/mao.0000000000001927] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE High-resolution flat panel computed tomography (FPCT) is useful for the evaluation of temporal bone pathologies. While radiation exposure remains a concern, efforts have been devoted to reduce dose, while maintaining image quality. We hypothesize that removing the antiscatter grid (ASG) results in decreased radiation exposure, while maintaining diagnostic image quality for the evaluation of superior semicircular canal dehiscence (SSCD). METHODS Ten patients with clinical suspicion for SSCD participated in this prospective study. Two sequential collimated 20-second FPCT acquisitions were performed (first: grid in; second: grid removed) in all patients. Secondary reconstructions were created by manually generating the volume of interest to include the middle ear using a voxel size of 0.1 mm and 512 × 512 matrix. Radiation dose parameters (air kerma (Ka,r) in mGy and dose area product (DAP) in μGym) were recorded. Three reviewers analyzed images for the ability to diagnose SSCD, to identify the stapes crurae, and to determine if an ASG was present. RESULTS The average Ka,r and DAP for the grid-in acquisitions were 246.7 mGy (SD 47.9) and 2838.0 μGym (SD 862.8), versus 160.2 mGy (SD 33.2) and 2026.3 μGym (SD 644.8) for the grid-out acquisitions, respectively (p<0.001 for both Ka,r and DAP). Radiation exposure was reduced by approximately 30% solely by removing the ASG. All reviewers correctly identified all patients with SSCD (confirmed at surgery), with mean AUC of 0.99 (κ = 0.90). CONCLUSION Removing the antiscatter grid during FPCT imaging of the temporal bones is a simple and effective way to reduce radiation exposure while maintaining diagnostic image quality for the evaluation of SSCD.
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The Insertion Results of a Mid-scala Electrode Assessed by MRI and CBCT Image Fusion. Otol Neurotol 2019; 39:e1019-e1025. [PMID: 30444847 DOI: 10.1097/mao.0000000000002045] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To investigate the results of clinical surgical insertions with a Mid-scala array (HIFocus Mid-Scala Electrode, HFms). STUDY DESIGN Consecutive retrospective case study. SETTINGS Tertiary referral center. PATIENTS Analyses of imaging data of 26 consecutive patients (31 insertions) implanted with the HFms. INTERVENTION (S) The evaluation of insertion trauma evoked by a previously validated image fusion technique. Electrode reconstructions from postoperative cone-beam computed tomography (CBCT) were overlaid onto preoperative magnetic resonance imaging (MRI) scans to create artifact-free images. MAIN OUTCOME MEASURES The electrode position was quantified in relation to the basilar membrane. Trauma scaling adopted from Eshraghi was used for evaluating insertion trauma. The results of the visual assessment of the postoperative CBCT were compared to those obtained with the fusion technique. RESULTS Three insertions had to be excluded due to incompatibility of the imaging data with the fusion software. We found consistent peri- to mid-modiolar placement of the HFms with a mean insertion depth angle of 376°. According to the medical records, a visual examination of the postoperative CBCT indicated that there had been no scala dislocations but when assessed by the image fusion technique, five scala dislocations (17.8%) were found. Additionally, one tip fold-over was detected in the postoperative CBCT even though this was not evident in any intraoperative measurements. CONCLUSION HFms showed atraumatic surgical insertion results with consistent mid-modiolar placement. Image fusion enhances the accuracy of the insertion trauma assessment. Routine postoperative imaging is recommended for identifying tip fold-over as well as for quality control and documentation.
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Merged Volume Rendered Flat-panel Computed Tomography for Postoperative Cochlear Implant Assessment. Clin Neuroradiol 2019; 30:721-728. [PMID: 31489450 DOI: 10.1007/s00062-019-00832-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 08/16/2019] [Indexed: 10/26/2022]
Abstract
PURPOSE Evaluation of a new postprocessing method for postoperative control of cochlear implants (CI) based on a single flat detector computed tomography (FD-CT) run and volume rendering of 3D models of the inner ear. METHODS The FD-CT datasets of CIs were selected and postprocessed to generate both standard multiplanar reconstructions (MPR) and merged volume-rendered 3D datasets (MRD) of the CIs. The MRDs consisted of two different reconstructions (bone/implant) that are automatically layered to avoid manual coregistration inaccuracy. Corresponding datasets were evaluated in consensus reading in terms of qualitative (integrity, position, configuration) and quantitative (insertion depth angle) CI parameters. RESULTS In total 20 FD-CTs with 20 CIs were successfully postprocessed. Qualitative evaluation of MPR and MRD demonstrated complete congruency (integrity: narray integrity = 20; position: nscala tympani = 13, nscalar translocation = 7; configuration: nharmonic spiralization = 16, ntip fold over = 3, nlooped implant = 1). Adverse intracochlear implant spiralization was identified in all 10 cases with MRD and MPR. Measurement of the insertion depth angle in MRD was equivalent to that in MPR (r = 0.99; P = <0.0001). CONCLUSION The use of MRD is a helpful method for precise postoperative CI assessment and provides easy detection of incorrect intracochlear spiralization.
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Cisneros Lesser JC, de Brito R, Queiroz Martins GDS, Gebrim EMMS, Bento RF. Evaluating Intracochlear Trauma after Cochlear Implant Electrode Insertion through Middle Fossa Approach in Temporal Bones. Otolaryngol Head Neck Surg 2017; 158:350-357. [DOI: 10.1177/0194599817739837] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objective To evaluate cochlear trauma after cochlear implant insertion through a middle fossa approach by means of histologic and imaging studies in temporal bones. Study Design Prospective cadaveric study. Setting University-based temporal bone laboratory. Subjects and Methods Twenty fresh-frozen temporal bones were implanted through a middle cranial fossa basal turn cochleostomy. Ten received a straight electrode and 10 a perimodiolar electrode. Samples were fixed in epoxy resin. Computed tomography (CT) scans determined direction, depth of insertion, and the cochleostomy to round window distance. The samples were polished by a microgrinding technique and microscopically visualized to evaluate intracochlear trauma. Descriptive and analytic statistics were performed to compare both groups. Results The CT scan showed intracochlear insertions in every bone, 10 directed to the middle/apical turn and 10 to the basal turn. In the straight electrode group, the average number of inserted electrodes was 12.3 vs 15.1 for the perimodiolar group ( U = 78, P = .0001). The median insertion depth was larger for the perimodiolar group (14.4 mm vs 12.5 mm, U = 66, P = .021). Only 1 nontraumatic insertion was achieved and 14 samples (70%) had important trauma (Eshraghi grades 3 and 4). No differences were identified comparing position or trauma grades for the 2 electrode models or when comparing trauma depending on the direction of insertion. Conclusion The surgical technique allows a proper intracochlear insertion, but it does not guarantee a correct scala tympani position and carries the risk of important trauma to cochlear microstructures.
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Affiliation(s)
- Juan Carlos Cisneros Lesser
- Otorhinolaryngology Department, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
- Otorhinolaryngology Department, National Institute of Rehabilitation, Mexico City, Mexico
| | - Rubens de Brito
- Otorhinolaryngology Department, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | | | | | - Ricardo Ferreira Bento
- Otorhinolaryngology Department, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
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