Stefan Hunsche1, Mohammad Maarouf1, Clemens Neudorfer2. 1. Department for Stereotaxy and Functional Neurosurgery, Center of Neurosurgery, Cologne-Merheim Medical Center (CMMC), University of Witten/Herdecke, Cologne, Germany. 2. Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
Abstract
BACKGROUND: The employment of the O-arm for intraoperative localization of deep brain stimulation (DBS) leads has been shown to be feasible and effective. However, partial volume artifacts impede the determination of individual electrode contacts and thus allow only an indirect approximation of each contact's localization. OBJECTIVE: To reduce the partial volume artifacts by means of high-resolution (HiRes) reconstruction of O-arm data and thus allow more accurate predictions with regard to the positioning and orientation of individual DBS contacts. METHODS: Following intraoperative flat-panel computed tomography, the O-arm raw data were reconstructed with a resolution of 0.2 mm × 0.2 mm × 0.2 mm. The geometric integrity of HiRes reconstructions was assessed via landmark transformation. Using a phantom, resolutions of both reconstruction modalities were then evaluated by means of the modulation transfer function (MTF). Finally, directional and nondirectional leads were compared visually to analyze the delineation of individual electrode contacts. RESULTS: With a mean accuracy of 0.56 mm ± 0.12 mm, geometric integrity remained intact during HiRes reconstruction. Analysis of HiRes reconstruction resolution yielded a 47.7% increase of the 10% MTF in comparison to conventional postprocessing. Reduction of partial volume artifacts yielded strong contrasts of electrode compartments and allowed direct identification of individual contacts as well as localization of the X-ray marker on directional leads. CONCLUSION: HiRes reconstruction of O-arm data allows an effective reduction of partial volume artifacts to such an extent that a delineation of individual contacts across single DBS leads is possible without requiring increases in radiation dose.
BACKGROUND: The employment of the O-arm for intraoperative localization of deep brain stimulation (DBS) leads has been shown to be feasible and effective. However, partial volume artifacts impede the determination of individual electrode contacts and thus allow only an indirect approximation of each contact's localization. OBJECTIVE: To reduce the partial volume artifacts by means of high-resolution (HiRes) reconstruction of O-arm data and thus allow more accurate predictions with regard to the positioning and orientation of individual DBS contacts. METHODS: Following intraoperative flat-panel computed tomography, the O-arm raw data were reconstructed with a resolution of 0.2 mm × 0.2 mm × 0.2 mm. The geometric integrity of HiRes reconstructions was assessed via landmark transformation. Using a phantom, resolutions of both reconstruction modalities were then evaluated by means of the modulation transfer function (MTF). Finally, directional and nondirectional leads were compared visually to analyze the delineation of individual electrode contacts. RESULTS: With a mean accuracy of 0.56 mm ± 0.12 mm, geometric integrity remained intact during HiRes reconstruction. Analysis of HiRes reconstruction resolution yielded a 47.7% increase of the 10% MTF in comparison to conventional postprocessing. Reduction of partial volume artifacts yielded strong contrasts of electrode compartments and allowed direct identification of individual contacts as well as localization of the X-ray marker on directional leads. CONCLUSION: HiRes reconstruction of O-arm data allows an effective reduction of partial volume artifacts to such an extent that a delineation of individual contacts across single DBS leads is possible without requiring increases in radiation dose.
Authors: Thomas Linsenmann; Andrea Cattaneo; Alexander März; Judith Weiland; Christian Stetter; Robert Nickl; Thomas Westermaier Journal: BMC Med Imaging Date: 2021-06-03 Impact factor: 1.930