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ABSTRACT: In current practice, optimal placement of deep-brain stimulators (DBSs) used to treat movement disorders in patients with Parkinson's disease and essential tremor is an iterative procedure. A target is chosen preoperatively based on anatomical landmarks identified on magnetic resonance images. This point is used as an initial position that is refined intraoperatively using both microelectrode recordings and macrostimulation. In this paper, we report on our current progress toward developing a system for the computer-assisted preoperative selection of target points and for the intraoperative adjustment of these points. The system consists of a deformable atlas of optimal target points that can be used to select automatically the preoperative target, of an electrophysiological atlas, and of an intraoperative interface. Results we have obtained show that automatic prediction of target points is an achievable goal. Our results also indicate that electrophysiological information could be used to resolve structures not visible in anatomic images, thus improving both preoperative and intraoperative guidance. Our intraoperative system has reached the stage of a working prototype and we compare targeting accuracy as well as the number of paths needed to reach the targets with our system and with the method in current clinical use.
IEEE Transactions on Medical Imaging 12/2005; 24(11):1469-78. · 3.64 Impact Factor
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ABSTRACT: Image-guided surgery will permit accurate access to the middle ear via the facial recess using a single drill hole from the lateral aspect of the mastoid cortex.
The widespread use of image-guided methods in otologic surgery has been limited by the need for a system that achieves the necessary level of accuracy with an easy-to-use, noninvasive fiducial marker system. We have developed and recently reported such a system (accuracy within the temporal bone = 0.76 +/- 0.23 mm; n = 234 measurements). With this system, image-guided otologic surgery is feasible.
Skulls (n = 2) were fitted with a dental bite-block affixed fiducial frame and scanned by computed tomography using standard temporal-bone algorithms. The frame was removed and replaced with an infrared emitter used to track the skull during dissection. Tracking was accomplished using an infrared tracker and commercially available software. Using this system in conjunction with a tracked otologic drill, the middle ear was approached via the facial recess using a single drill hole from the lateral aspect of the mastoid cortex. The path of the drill was verified by subsequently performing a traditional temporal bone dissection, preserving the tunnel of bone through which the drill pass had been made.
An accurate approach to the middle ear via the facial recess was achieved without violating the canal of the facial nerve, the horizontal semicircular canal, or the external auditory canal.
Image-guided otologic surgery provides access to the cochlea via the facial recess in a minimally invasive, percutaneous fashion. While the present study was confined to in vitro demonstration, these exciting results warrant in vivo testing, which may lead to clinically applicable access.
Ontology & Neurotology 08/2005; 26(4):557-62. · 1.90 Impact Factor
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ABSTRACT: Application of image-guided surgery to otology has been limited by the need for submillimeter accuracy via a fiducial system that is easily usable (noninvasive and nonobstructive).
A dental bite-block was fitted with a rigid frame with 7 fiducial markers surrounding each external ear. The temporal bones of 3 cadaveric skulls were removed and replaced with surgical targets arranged in a bull's-eye pattern about the centroid of each temporal bone. The surgical targets were identified both within CT scans and in physical space using an infrared optical tracking system. The difference between positions in CT space versus physical space was calculated as target registration error.
A total of 234 independent target registration errors were calculated. Mean +/- standard deviation = 0.73 mm +/- 0.25 mm.
These findings show that image-guided otologic surgery with submillimeter accuracy is achievable with a minimally invasive fiducial frame. Significance In vivo validation of the system is ongoing. With such validation, this system may facilitate clinically applicable image-guided otologic surgery. EBM rating: A.
Otolaryngology Head and Neck Surgery 04/2005; 132(3):435-42. · 1.72 Impact Factor
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ABSTRACT: In this study, a new system was evaluated for implanting deep-brain stimulators based on a one-piece platform for each trajectory customized from a preoperative planning image. During surgery, the platform is attached to skull-implanted posts that extend through the scalp. The platform acts as a miniature stereotactic frame to provide guidance for parallel cannulas as they are advanced through a burr hole to the target. Accuracy is determined from a postoperative CT. For each implantation, the distance between the position observed in the postoperative image and the position calculated relative to the platform from the preoperative image is our measure of error. Because this measure incorporates the surgical error of electrode anchoring, brain shift between preoperative and postoperative scanning, and error in the measurement of the position of the electrode in CT, it will tend to overestimate the true error. The mean error was 2.8 mm for 20 implantations. These data reflect favorably the accuracy of this system when compared with others.
Stereotactic and Functional Neurosurgery 02/2005; 83(1):25-31. · 1.85 Impact Factor
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IEEE Trans. Med. Imaging. 01/2005; 24:1469-1478.
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ABSTRACT: In current practice, optimal placement of deep brain stimulators (DBSs) is an iterative procedure. A target is chosen pre-operatively
based on anatomical landmarks identified on MR images. This point is used as an initial position that is refined intra-operatively
using both micro-electrode recordings and macro-stimulation. We hypothesize that boundaries of nuclei and sub-nuclei not visible
in the anatomic images can be resolved in atlases that include electrophysiological information, thus improving both pre-
and intra-operative guidance. In this work we report on our current progress toward creating such an atlas. We also present
results we have obtained in creating an atlas of optimal target points that can be used for automatic pre-operative selection
of the targets. We demonstrate that initial points selected with this atlas are closer to the final points than the initial
points chosen manually.
09/2004: pages 729-736;
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Medical Image Computing and Computer-Assisted Intervention -- MICCAI 2004, 7th International Conference Saint-Malo, France, September 26-29, 2004, Proceedings, Part I; 01/2004
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ABSTRACT: Otologic surgery is undertaken to treat ailments of the ear, including persistent infections, hearing loss, vertigo, and cancer. Typically performed on otherwise-healthy patients in outpatient facilities, the application of image-guided surgery (IGS) has been limited because accurate (<1 mm), non-invasive fiducial systems for otologic surgery have not been available. We now present such a fiducial system.
A dental bite-block was fitted with a custom-designed rigid frame with 7 fiducial markers surrounding each external ear. The bones containing the ear (i.e., the temporal bones) of 3 cadaveric skulls were removed and replaced with discs containing 13 surgical targets arranged in a cross-hair pattern about the centroid of each ear. The surgical targets (26/skull) and fiducial markers (14/skull) were identified both within CT scans using a published algorithm and in physical space using an infrared optical tracking system. Fiducial registration error (FRE), fiducial localization error (FLE), and target registration error (TRE) were calculated.
For all trials, root mean square FRE = 0.66, FLE = 0.72, and TRE = 0.77 mm. The mean TRE for n = 234 independent targets was 0.73 with a standard deviation of 0.25 mm.
Using a novel, non-invasive fiducial system (the EarMark), submillimetric accuracy was repeatably achieved. This system will facilitate image-guided otologic surgery.
Computer Aided Surgery 01/2004; 9(4):145-53. · 0.30 Impact Factor
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Biomedical Image Registration, Second International Workshop, WBIR 2003, Philadelphia, PA, USA, June 23-24, 2003, Revised Papers; 01/2003
