15 results on '"Benoit M. Dawant"'
Search Results
2. 508 Deep Learning Segmentation of the Nucleus Basalis of Meynert for Deep Brain Stimulation Surgical Planning
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Derek Doss, Graham Walter Johnson, Saramati Narasimhan, Jasmine Jiang, Hernan F.J. Gonzalez, Danika Lea Paulo, Catie Chang, Victoria Morgan, Christos Constantinidis, Benoit M. Dawant, and Dario J. Englot more...
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Surgery ,Neurology (clinical) - Published
- 2023
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Catalog
3. 205 Optimization of DBS Electrode Position With Multisite Microelectrode Recordings, Macrostimulation, and Atlas-Based Prediction Maps Visualized in 3D
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Danika L. Paulo, Saramati Narasimhan, Hernan F. J. Gonzalez, William Rodriguez, Rui Li, Peter Konrad, Joseph S. Neimat, Hamid M. Shah, Sarah K. B. Bick, Pierre D'Haese, Benoit M. Dawant, and Dario J. Englot more...
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Surgery ,Neurology (clinical) - Published
- 2022
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4. Resting-State SEEG May Help Localize Epileptogenic Brain Regions
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Benoit M. Dawant, William Rodriguez, John D. Rolston, Victoria L. Morgan, Kanupriya Gupta, Sarah E Goodale, Robert Shults, Hernán F J González, Dario J. Englot, Graham W. Johnson, and Baxter P. Rogers more...
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Adult ,Male ,Rest ,Electroencephalography ,Neurosurgical Procedures ,Stereoelectroencephalography ,Cohort Studies ,Stereotaxic Techniques ,03 medical and health sciences ,Epilepsy ,Imaging, Three-Dimensional ,0302 clinical medicine ,medicine ,Humans ,030304 developmental biology ,Brain Mapping ,0303 health sciences ,Resting state fMRI ,medicine.diagnostic_test ,business.industry ,Functional connectivity ,Brain ,Middle Aged ,medicine.disease ,Intracranial eeg ,Research—Human—Clinical Studies ,Female ,Surgery ,Epilepsies, Partial ,Neurology (clinical) ,business ,Neuroscience ,030217 neurology & neurosurgery - Abstract
BACKGROUND: Stereotactic electroencephalography (SEEG) is a minimally invasive neurosurgical method to localize epileptogenic brain regions in epilepsy but requires days in the hospital with interventions to trigger several seizures. OBJECTIVE: To make initial progress in the development of network analysis methods to identify epileptogenic brain regions using brief, resting-state SEEG data segments, without requiring seizure recordings. METHODS: In a cohort of 15 adult focal epilepsy patients undergoing SEEG, we evaluated functional connectivity (alpha-band imaginary coherence) across sampled regions using brief (2 min) resting-state data segments. Bootstrapped logistic regression was used to generate a model to predict epileptogenicity of individual regions. RESULTS: Compared to nonepileptogenic structures, we found increased functional connectivity within epileptogenic regions (P more...
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- 2019
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5. Clinical Implementation of Second-generation Minimally Invasive Image-guided Cochlear Implantation Surgery
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Benoit M. Dawant, Katherine E. Riojas, Jack H. Noble, J. Michael Fitzpatrick, Trevor L. Bruns, Jason E. Mitchell, Robert F. Labadie, Kathleen Von Wahlde, and Robert J. Webster
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medicine.medical_specialty ,Investigational device exemption ,Mastoid ,03 medical and health sciences ,0302 clinical medicine ,otorhinolaryngologic diseases ,Electrode array ,Humans ,Minimally Invasive Surgical Procedures ,Medicine ,030223 otorhinolaryngology ,Adverse effect ,Cochlear implantation ,Aged ,business.industry ,Soft tissue ,Evidence-based medicine ,medicine.disease ,Cochlear Implantation ,Sensory Systems ,Cochlea ,Surgery ,Clinical trial ,Cochlear Implants ,Surgery, Computer-Assisted ,Otorhinolaryngology ,Sensorineural hearing loss ,Neurology (clinical) ,business ,030217 neurology & neurosurgery - Abstract
Objective Minimally invasive, image-guided cochlear implantation (CI) surgery consists of drilling a precise tunnel from the surface of the mastoid cortex through the facial recess to target the scala tympani. In the first set of clinical trials of this technique, heat-induced facial nerve paresis (House-Brackmann II/VI) occurred on a patient on the last day of the initial trial which was scheduled to be halted secondary to a change in the regulatory requirements dictated by the 2012 the Food and Drug Administration Safety and Innovation Act requiring Investigational Device Exemption approval for previously exempted customized medical device testing. To address this adverse event, extensive changes were made to the drilling protocol; additionally, a custom insertion tool was developed. To address the Food and Drug Administration Safety and Innovation Act, an Investigational Device Exemption was submitted and, subsequently approved. Herein is described our first clinical implementation of the modified technique. Patient Seventy-year-old with profound, postlingual sensorineural hearing loss who had previously undergone right CI via traditional approach in 2015. Intervention Minimally invasive image-guided left CI. Main outcome measure Time of intervention, final location of CI electrode array within cochlea. Results Surgery took 155 minutes of which the largest components (in descending order) were soft tissue work, closure, and drilling. Full scala tympani insertion with angular insertion depth of 557 degrees of the electrode array was achieved. There were no complications, and the patient had an uneventful recovery and activation. Conclusions Minimally invasive, image-guided CI surgery is achievable and reduces the mastoid depression associated with traditional CI surgery. Clinicaltrialsgov information Study NCT03101917, Microtable Microstereotactic Frame and Drill Press and Associated Method for Cochlear Implantation. Level of evidence Case Report. more...
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- 2021
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6. Intra-Cochlear Electrocochleography During Cochear Implant Electrode Insertion Is Predictive of Final Scalar Location
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Jameson K. Mattingly, Amanda J. Ortmann, Craig A. Buchman, Carla V. Valenzuela, Robert T. Dwyer, Michael M Harris, Brendan P O'Connell, Leonid M. Litvak, Jack H. Noble, William J. Riggs, Kanthaiah Koka, Jourdan T. Holder, Robert F. Labadie, Benoit M. Dawant, and Oliver F. Adunka more...
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Adult ,Male ,Intraoperative Neurophysiological Monitoring ,Hearing loss ,medicine.medical_treatment ,Article ,03 medical and health sciences ,0302 clinical medicine ,Cochlear implant ,Electrode array ,Humans ,Medicine ,030223 otorhinolaryngology ,medicine.diagnostic_test ,business.industry ,Electrocochleography ,Cochlear Implantation ,Sensory Systems ,Audiometry, Evoked Response ,Cochlea ,Basilar membrane ,Cochlear Implants ,Otorhinolaryngology ,Electrode ,Female ,Neurology (clinical) ,Implant ,medicine.symptom ,Audiometry ,business ,Nuclear medicine ,030217 neurology & neurosurgery - Abstract
Hypothesis Electrocochleography (ECochG) patterns observed during cochlear implant (CI) electrode insertion may provide information about scalar location of the electrode array. Background Conventional CI surgery is performed without actively monitoring auditory function and potential damage to intracochlear structures. The central hypothesis of this study was that ECochG obtained directly through the CI may be used to estimate intracochlear electrode position and, ultimately, residual hearing preservation. Methods Intracochlear ECochG was performed on 32 patients across 3 different implant centers. During electrode insertion, a 50-ms tone burst stimulus (500 Hz) was delivered at 110 dB SPL. The ECochG response was monitored from the apical-most electrode. The amplitude and phase changes of the first harmonic were imported into an algorithm in an attempt to predict the intracochlear electrode location (scala tympani [ST], translocation from ST to scala vestibuli [SV], or interaction with basilar membrane). Anatomic electrode position was verified using postoperative computed tomography (CT) with image processing. Results CT analysis confirmed 25 electrodes with ST position and 7 electrode arrays translocating from ST into SV. The ECochG algorithm correctly estimated electrode position in 26 (82%) of 32 subjects while 6 (18%) electrodes were wrongly identified as translocated (sensitivity = 100%, specificity = 77%, positive predictive value = 54%, and a negative predictive value = 100%). Greater hearing loss was observed postoperatively in participants with translocated electrode arrays (36 ± 15 dB) when compared with isolated ST insertions (28 ± 20 dB HL). This result, however, was not significant (p = 0.789). Conclusion Intracochlear ECochG may provide information about CI electrode location and hearing preservation. more...
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- 2018
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7. Image-guided Cochlear Implant Programming for Pediatric CI Recipients
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Benoit M. Dawant, Jack H. Noble, René H. Gifford, Stephen Camarata, Robert F. Labadie, Linsey W. Sunderhaus, and Emily Byram
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Speech and Hearing ,medicine.medical_specialty ,business.industry ,Cochlear implant ,medicine.medical_treatment ,medicine ,Audiology ,business - Published
- 2020
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8. Evaluation of Rigid Cochlear Models for Measuring Cochlear Implant Electrode Position
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Robert F. Labadie, Benoit M. Dawant, M. Geraldine Zuniga, Jack H. Noble, and Ahmet Cakir
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Adult ,Male ,Models, Anatomic ,medicine.medical_specialty ,medicine.medical_treatment ,Cochlear duct ,Audiology ,Article ,03 medical and health sciences ,0302 clinical medicine ,Position (vector) ,Cochlear implant ,otorhinolaryngologic diseases ,medicine ,Humans ,030223 otorhinolaryngology ,Cochlea ,business.industry ,Cochlear Implantation ,Sensory Systems ,Basilar membrane ,Cochlear Implants ,medicine.anatomical_structure ,Modiolus (cochlea) ,Otorhinolaryngology ,Electrode ,Female ,sense organs ,Neurology (clinical) ,Tomography ,Tomography, X-Ray Computed ,business ,030217 neurology & neurosurgery ,Biomedical engineering - Abstract
Objective To investigate the accuracy of rigid cochlear models in measuring intra-cochlear positions of cochlear implant (CI) electrodes. Patients Ninety three adults who had undergone CI and pre- and postoperative computed tomographic (CT) imaging. Main outcome measures Seven rigid models of cochlear anatomy were constructed using micro-CTs of cochlear specimens. Using each of the seven models, the position of each electrode in each of the 98 ears in our dataset was measured as its depth along the length of the cochlea, its distance to the basilar membrane, and its distance to the modiolus. Cochlear duct length was also measured using each model. Results Standard deviation (SD) across rigid cochlear models in measures of electrode depth, distance to basilar membrane, distance to modiolus, and length of the cochlear duct at two turns were 0.68, 0.11, 0.15, and 1.54 mm. Comparing the estimated position of the electrodes with respect to the basilar membrane, i.e., deciding whether an electrode was located within the scala tympani (ST) or the scala vestibuli (SV), there was not a unanimous agreement between the models for 19% of all the electrodes. With respect to the modiolus, each electrode was classified into one of the three groups depending on its modiolar distance: close, medium, and far. Rigid models did not unanimously agree on modiolar distance for approximately 50% of the electrodes tested. Conclusions Inter-model variance of rigid cochlear models exists, demonstrating that measurements made using rigid cochlear models are limited in terms of accuracy because of non-rigid inter-subject variations in cochlear anatomy. more...
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- 2016
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9. Initial Results With Image-guided Cochlear Implant Programming in Children
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Andrea Hedley-Williams, Jack H. Noble, Stephen Camarata, Benoit M. Dawant, Robert F. Labadie, René H. Gifford, and Linsey W. Sunderhaus
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Adult ,Male ,medicine.medical_specialty ,Adolescent ,Wilcoxon signed-rank test ,Language delay ,Hearing loss ,medicine.medical_treatment ,MEDLINE ,Audiology ,01 natural sciences ,Article ,03 medical and health sciences ,0302 clinical medicine ,Hearing ,Cochlear implant ,0103 physical sciences ,medicine ,Humans ,Child ,030223 otorhinolaryngology ,Image guidance ,010301 acoustics ,Language ,business.industry ,Infant ,Cochlear Implantation ,Sensory Systems ,Sentence recognition ,Cochlea ,Clinical trial ,Cochlear Implants ,Otorhinolaryngology ,Radiographic Image Interpretation, Computer-Assisted ,Female ,Neurology (clinical) ,medicine.symptom ,Tomography, X-Ray Computed ,business ,Software - Abstract
HYPOTHESIS Image-guided cochlear implant (CI) programming can improve hearing outcomes for pediatric CI recipients. BACKGROUND CIs have been highly successful for children with severe-to-profound hearing loss, offering potential for mainstreamed education and auditory-oral communication. Despite this, a significant number of recipients still experience poor speech understanding, language delay, and, even among the best performers, restoration to normal auditory fidelity is rare. Although significant research efforts have been devoted to improving stimulation strategies, few developments have led to significant hearing improvement over the past two decades. Recently introduced techniques for image-guided CI programming (IGCIP) permit creating patient-customized CI programs by making it possible, for the first time, to estimate the position of implanted CI electrodes relative to the nerves they stimulate using CT images. This approach permits identification of electrodes with high levels of stimulation overlap and to deactivate them from a patient's map. Previous studies have shown that IGCIP can significantly improve hearing outcomes for adults with CIs. METHODS The IGCIP technique was tested for 21 ears of 18 pediatric CI recipients. Participants had long-term experience with their CI (5 mo to 13 yr) and ranged in age from 5 to 17 years old. Speech understanding was assessed after approximately 4 weeks of experience with the IGCIP map. RESULTS Using a two-tailed Wilcoxon signed-rank test, statistically significant improvement (p < 0.05) was observed for word and sentence recognition in quiet and noise, as well as pediatric self-reported quality-of-life (QOL) measures. CONCLUSION Our results indicate that image guidance significantly improves hearing and QOL outcomes for pediatric CI recipients. more...
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- 2016
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10. Relationship Between Electrode-to-Modiolus Distance and Current Levels for Adults With Cochlear Implants
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Benoit M. Dawant, Timothy J. Davis, René H. Gifford, Robert F. Labadie, Jack H. Noble, and Dongqing Zhang
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Adult ,medicine.medical_treatment ,Straight electrode ,Stimulation ,Article ,Correlation ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,Cochlear implant ,Humans ,Medicine ,030223 otorhinolaryngology ,Electrodes ,business.industry ,Equipment Design ,Middle Aged ,Cochlear Implantation ,Electric Stimulation ,Sensory Systems ,Cochlea ,Cochlear Implants ,Modiolus (cochlea) ,Acoustic Stimulation ,Otorhinolaryngology ,Position analysis ,Electrode ,Neurology (clinical) ,Tomography, X-Ray Computed ,business ,Lateral wall ,030217 neurology & neurosurgery ,Biomedical engineering - Abstract
HYPOTHESIS Electrode-to-modiolus distance is correlated with clinically programmed stimulation levels. BACKGROUND Conventional wisdom has long supposed a significant relationship between cochlear implant (CI) stimulation levels and electrode-to-modiolus distance; however, to date, no such formal investigation has been completed. Thus, the purpose of this project was to investigate the relationship between stimulation levels and electrode-to-modiolus distance. A strong correlation between the two would suggest that stimulation levels might be used to estimate electrode-to-modiolus geometry. METHODS Electrode-to-modiolus distance was determined via CT imaging using validated CI position analysis software in 137 implanted ears from the three manufacturers holding FDA approval in the United States. Analysis included 2,365 total electrodes, with 1,472 from precurved arrays. Distances were compared to clinically programmed C/M levels that were converted to charge units. RESULTS Mean modiolar distance with perimodiolar and lateral wall electrodes was 0.47 and 1.15 mm, respectively. Mean suprathreshold charge values were significantly different between each manufacturer. When combining all data, we found a moderate positive correlation (r = 0.367, p < 0.01) that was driven both by the different charge values across companies, and that the company with the highest mean charge values only offers straight electrode arrays. When grouped by electrode type, however, we found a weak correlation (r = 0.12, p < 0.01) for perimodiolar array electrodes only. When considering a single array type from any one manufacturer, only one was observed where distance mildly predicted charge. CONCLUSION Our results suggest that electrode distance minimally contributes to the current level required for suprathreshold stimulation. more...
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- 2016
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11. Fully Automated Targeting Using Nonrigid Image Registration Matches Accuracy and Exceeds Precision of Best Manual Approaches to Subthalamic Deep Brain Stimulation Targeting in Parkinson Disease
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Benoit M. Dawant, Joseph S. Neimat, Wendell B. Lake, Srivatsan Pallavaram, Pierre-François DʼHaese, and Peter E. Konrad
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medicine.medical_specialty ,Deep brain stimulation ,Deep Brain Stimulation ,medicine.medical_treatment ,Image registration ,Article ,Stereotaxic Techniques ,Imaging, Three-Dimensional ,Subthalamic Nucleus ,Atlas (anatomy) ,medicine ,Humans ,Computer vision ,Aged ,medicine.diagnostic_test ,business.industry ,Parkinson Disease ,Magnetic resonance imaging ,Middle Aged ,Magnetic Resonance Imaging ,Surgery ,Subthalamic nucleus ,medicine.anatomical_structure ,Surgery, Computer-Assisted ,Fully automated ,Direct targeting ,Stereotaxic technique ,Female ,Neurology (clinical) ,Artificial intelligence ,business - Abstract
Background Finding the optimal location for the implantation of the electrode in deep brain stimulation (DBS) surgery is crucial for maximizing the therapeutic benefit to the patient. Such targeting is challenging for several reasons, including anatomic variability between patients as well as the lack of consensus about the location of the optimal target. Objective To compare the performance of popular manual targeting methods against a fully automatic nonrigid image registration-based approach. Methods In 71 Parkinson disease subthalamic nucleus (STN)-DBS implantations, an experienced functional neurosurgeon selected the target manually using 3 different approaches: indirect targeting using standard stereotactic coordinates, direct targeting based on the patient magnetic resonance imaging, and indirect targeting relative to the red nucleus. Targets were also automatically predicted by using a leave-one-out approach to populate the CranialVault atlas with the use of nonrigid image registration. The different targeting methods were compared against the location of the final active contact, determined through iterative clinical programming in each individual patient. Results Targeting by using standard stereotactic coordinates corresponding to the center of the motor territory of the STN had the largest targeting error (3.69 mm), followed by direct targeting (3.44 mm), average stereotactic coordinates of active contacts from this study (3.02 mm), red nucleus-based targeting (2.75 mm), and nonrigid image registration-based automatic predictions using the CranialVault atlas (2.70 mm). The CranialVault atlas method had statistically smaller variance than all manual approaches. Conclusion Fully automatic targeting based on nonrigid image registration with the use of the CranialVault atlas is as accurate and more precise than popular manual methods for STN-DBS. more...
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- 2015
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12. Thalamic Arousal Network Disturbances in Temporal Lobe Epilepsy and Improvement After Surgery
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Benoit M. Dawant, Kanupriya Gupta, Daniel O. Claassen, Sarah E Goodale, Srijata Chakravorti, Victoria L. Morgan, Hernán F J González, and Dario J. Englot
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medicine.medical_specialty ,medicine.diagnostic_test ,business.industry ,Thalamus ,medicine.disease ,behavioral disciplines and activities ,Arousal ,Temporal lobe ,Surgery ,Epilepsy ,nervous system ,Medicine ,Epilepsy surgery ,Neurology (clinical) ,Occipital lobe ,business ,Functional magnetic resonance imaging ,Reticular activating system ,psychological phenomena and processes - Abstract
Objective The effects of temporal lobe epilepsy (TLE) on subcortical arousal structures remain incompletely understood. Here, we evaluate thalamic arousal network functional connectivity in TLE and examine changes after epilepsy surgery. Methods We examined 26 adult patients with TLE and 26 matched control participants and used resting-state functional MRI (fMRI) to measure functional connectivity between the thalamus (entire thalamus and 19 bilateral thalamic nuclei) and both neocortex and brainstem ascending reticular activating system (ARAS) nuclei. Postoperative imaging was completed for 19 patients >1 year after surgery and compared with preoperative baseline. Results Before surgery, patients with TLE demonstrated abnormal thalamo-occipital functional connectivity, losing the normal negative fMRI correlation between the intralaminar central lateral (CL) nucleus and medial occipital lobe seen in controls (p Conclusions Overall, patients with TLE demonstrate impaired connectivity in thalamic arousal networks that may be involved in visuospatial attention, but these disturbances may partially recover after successful epilepsy surgery. Thalamic arousal network dysfunction may contribute to morbidity in TLE. more...
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- 2019
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13. Comparison of Cochlear Implant Relevant Anatomy in Children Versus Adults
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Benoit M. Dawant, Mary S. Dietrich, Robert F. Labadie, Alejandro Rivas, Jack H. Noble, Fitsum A. Reda, and Theodore R. McRackan
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Adult ,Male ,Aging ,Tympanic Membrane ,Adolescent ,medicine.medical_treatment ,Ear, Middle ,Article ,Auditory canal ,Basal (phylogenetics) ,Cochlear implant ,Image Processing, Computer-Assisted ,Humans ,Medicine ,Ear canal ,Child ,Cochlea ,Aged ,Round window ,business.industry ,Infant ,Anatomy ,Middle Aged ,Cochlear Implantation ,Facial nerve ,Sensory Systems ,Cochlear Implants ,medicine.anatomical_structure ,Round Window, Ear ,Otorhinolaryngology ,Child, Preschool ,Middle ear ,Female ,sense organs ,Neurology (clinical) ,Otologic Surgical Procedures ,Tomography, X-Ray Computed ,business ,Ear Canal - Abstract
To test whether there are significant differences in pediatric and adult temporal bone anatomy as related to cochlear implant (CI) surgery.Surgeons rely upon anatomic landmarks including the round window (RW) and facial recess (FR) to place CI electrodes within the scala tympani. Anecdotally, clinicians report differences in orientation of such structures in children versus adults.Institutional review board approval was obtained. High-resolution computed tomographic scans of 24 pediatric patients (46 ears) and 20 adult patients (40 ears) were evaluated using software consisting of a model-based segmentation algorithm that automatically localizes and segments temporal bone anatomy (e.g., facial nerve, chorda tympani, external auditory canal [EAC], and cochlea). On these scans, angles pertinent anatomy were manually delineated and measured blinded as to the age of the patient.The EAC and FR were more parallel to the basal turn (BT) of the cochlea in children versus adults ([symbol in text] EAC:BT 20.55 degrees versus 24.28 degrees, p = 0.003; [symbol in text] FR:BT 5.15 degrees versus 6.88 degrees, p = 0.009). The RW was more closely aligned with the FR in children versus adults ([symbol in text] FR:RW 30.43 degrees versus 36.67 degrees, p = 0.009). Comparing the lateral portion of the EAC (using LatEAC as a marker) to the most medial portion (using [symbol in text] TM as a marker), the measured angle was 136.57 degrees in children and 172.20 degrees in adults (p0.001).There are significant differences in the temporal bone anatomy of children versus adults pertinent to CI electrode insertion. more...
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- 2012
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14. Clinical Validation Study of Percutaneous Cochlear Access Using Patient-Customized Microstereotactic Frames
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Benoit M. Dawant, Jason E. Mitchell, David S. Haynes, Marc L. Bennett, J. Michael Fitzpatrick, Ramya Balachandran, Omid Majdani, Robert F. Labadie, and Jack H. Noble
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Adult ,Male ,medicine.medical_specialty ,Percutaneous ,Adolescent ,medicine.medical_treatment ,Mastoidectomy ,Article ,Stereotaxic Techniques ,Monitoring, Intraoperative ,Cochlear implant ,Temporal bone ,otorhinolaryngologic diseases ,Humans ,Medicine ,Prospective Studies ,Hearing Loss ,Cochlea ,Aged ,Aged, 80 and over ,Orthodontics ,business.industry ,Patient Selection ,Equipment Design ,Middle Aged ,Cochlear Implantation ,Facial nerve ,Sensory Systems ,Surgery ,Radiography ,Cochlear Implants ,Treatment Outcome ,Otorhinolaryngology ,Ear, Inner ,Conventional PCI ,Female ,sense organs ,Neurology (clinical) ,business ,Fiducial marker - Abstract
OBJECTIVE Percutaneous cochlear implant (PCI) surgery consists of drilling a single trough from the lateral cranium to the cochlea avoiding vital anatomy. To accomplish PCI, we use a patient-customized microstereotactic frame, which we call a "microtable" because it consists of a small tabletop sitting on legs. The orientation of the legs controls the alignment of the tabletop such that it is perpendicular to a specified trajectory. STUDY DESIGN Prospective. SETTING Tertiary referral center. PATIENTS Thirteen patients (18 ears) undergoing traditional cochlear implant surgery. INTERVENTIONS With institutional review board approval, each patient had 3 fiducial markers implanted in bone surrounding the ear. Temporal bone computed tomographic scans were obtained, and the markers were localized, as was vital anatomy. A linear trajectory from the lateral cranium through the facial recess to the cochlea was planned. A microtable was fabricated to follow the specified trajectory. MAIN OUTCOME MEASURES After mastoidectomy and posterior tympanotomy, accuracy of trajectories was validated by mounting the microtables on the bone-implanted markers and then passing sham drill bits across the facial recess to the cochlea. The distance from the drill to vital anatomy was measured. RESULTS Microtables were constructed on a computer-numeric-control milling machine in less than 5 minutes each. Successful access across the facial recess to the cochlea was achieved in all 18 cases. The mean +/- SD distance was 1.20 +/- 0.36 mm from midportion of the drill to the facial nerve and 1.25 +/- 0.33 mm from the chorda tympani. CONCLUSION These results demonstrate the feasibility of PCI access using customized microstereotactic frames. more...
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- 2010
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15. Technical Note. Effect of Geometrical Distortion Correction in MR on Image Registration Accuracy
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J.M. Fitzpatrick, Calvin R. Maurer, Robert J. Maciunas, Georges B. Aboutanos, Benoit M. Dawant, Richard A. Margolin, and S. Gadamsetty
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business.industry ,Image registration ,Image processing ,Transformation (function) ,Distortion ,Stereotaxic technique ,Medicine ,Radiology, Nuclear Medicine and imaging ,Computer vision ,Tomography ,Image rectification ,Artificial intelligence ,Fiducial marker ,Nuclear medicine ,business - Abstract
In this article we investigate the effect of geometrical distortion correction in MR images on the accuracy of the registration of X-ray CT and MR head images for both a fiducial marker (extrinsic point) method and a surface-matching technique. We use CT and T2-weighted MR image volumes acquired from seven patients who underwent craniotomies in a stereotactic neurosurgical clinical trial. Each patient had four external markers attached to transcutaneous posts screwed into the outer table of the skull. The MR images are corrected for static field inhomogeneity by using an image rectification technique and corrected for scale distortion (gradient magnitude uncertainty) by using an attached stereotactic frame as an object of known shape and size. We define target registration error (TRE) as the distance between corresponding marker positions after registration and transformation. The accuracy of the fiducial marker method is determined by using each combination of three markers to estimate the transformation and the remaining marker to calculate registration error. Surface-based registration is accomplished by fitting MR contours corresponding to the CSF-dura interface to CT contours derived from the inner surface of the skull. The mean point-based TRE using three noncollinear fiducials improved 34%-from 1.15 to 0.76 mm-after correcting for both static field inhomogeneity and scale distortion. The mean surface-based TRE improved 46%-from 2.20 to 1.19 mm. Correction of geometrical distortion in MR images can significantly improve the accuracy of point-based and surface-based registration of CT and MR head images. Distortion correction can be important in clinical situations such as stereotactic and functional neurosurgery where 1 to 2 mm accuracy is required. more...
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- 1996
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