J Neurol Surg B Skull Base 2021; 82(S 03): e306-e314
DOI: 10.1055/s-0040-1701211
Original Article

Evaluating an Image-Guided Operating Room with Cone Beam CT for Skull Base Surgery

Nidal Muhanna
1   Department of Otolaryngology, Head and Neck Surgery, University of Toronto, Toronto, Canada
2   Department of Surgical Oncology, Toronto General Hospital and Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
3   Department of Otolaryngology, Head and Neck and Maxillofacial Surgery, Tel-Aviv Sourasky Medical Center—Tel Aviv University, Tel Aviv-Yafo, Israel
,
1   Department of Otolaryngology, Head and Neck Surgery, University of Toronto, Toronto, Canada
2   Department of Surgical Oncology, Toronto General Hospital and Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
,
Michael J. Daly
4   TECHNA Institute, University Health Network, Toronto, Ontario, Canada
,
Harley H.L. Chan
4   TECHNA Institute, University Health Network, Toronto, Ontario, Canada
,
Robert Weersink
4   TECHNA Institute, University Health Network, Toronto, Ontario, Canada
5   Department of Medical Physics, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
,
Jason Townson
4   TECHNA Institute, University Health Network, Toronto, Ontario, Canada
,
Eric Monteiro
1   Department of Otolaryngology, Head and Neck Surgery, University of Toronto, Toronto, Canada
,
Eugene Yu
6   Joint Department of Medical Imaging, University Health Network/Mt. Sinai Hospital, Toronto, Ontario, Canada
,
Emilie Weimer
6   Joint Department of Medical Imaging, University Health Network/Mt. Sinai Hospital, Toronto, Ontario, Canada
,
Walter Kucharczyk
6   Joint Department of Medical Imaging, University Health Network/Mt. Sinai Hospital, Toronto, Ontario, Canada
,
David A. Jaffray
5   Department of Medical Physics, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
6   Joint Department of Medical Imaging, University Health Network/Mt. Sinai Hospital, Toronto, Ontario, Canada
,
Jonathan C. Irish
1   Department of Otolaryngology, Head and Neck Surgery, University of Toronto, Toronto, Canada
2   Department of Surgical Oncology, Toronto General Hospital and Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
4   TECHNA Institute, University Health Network, Toronto, Ontario, Canada
,
John R. de Almeida
1   Department of Otolaryngology, Head and Neck Surgery, University of Toronto, Toronto, Canada
2   Department of Surgical Oncology, Toronto General Hospital and Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
› Author Affiliations

Funding This work was supported by research funding from Siemens Healthcare, the AHSC AFP Innovation Fund (Ontario Ministry of Health and Long Term Care), and the Princess Margaret Cancer Foundation.
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Abstract

Importance Skull base surgery requires precise preoperative assessment and intraoperative management of the patient. Surgical navigation is routinely used for complex skull base cases; however, the image guidance is commonly based on preoperative scans alone.

Objective The primary objective of this study was to assess the image quality of intraoperative cone-beam computed tomography (CBCT) within anatomical landmarks used in sinus and skull base surgery. The secondary objective was to assess the registration error of a surgical navigation system based on intraoperative CBCT.

Design Present study is a retrospective case series of image quality after intraoperative cone beam CT.

Setting The study was conducted at Toronto General Hospital and Princess Margaret Cancer Centre, University Health Network, Toronto.

Participants A total of 46 intraoperative scans (34 patients, 21 skull base, 13 head and neck) were studied.

Main Outcome and Measures Thirty anatomical landmarks (vascular, soft tissue, and bony) within the sinuses and anterior skull base were evaluated for general image quality characteristics: (1) bony detail visualization; (2) soft-tissue visualization; (3) vascular visualization; and (4) freedom from artifacts (e.g., metal). Levels of intravenous (IV) contrast enhancement were quantified in Hounsfield's units (HU). Standard paired-point registration between imaging and tracker coordinates was performed using 6 to 8 skin fiducial markers and the corresponding fiducial registration error (FRE) was measured.

Results Median score for bony detail on CBCT was 5, remaining at 5 after administration of IV contrast. Median soft-tissue score was 2 for both pre- and postcontrast. Median vascular score was 1 precontrast and 3 postcontrast. Median score for artifacts on CBCT were 2 for both pre-and postcontrast, and metal objects were noted to be the most significant source of artifact. Intraoperative CBCT allowed preresection images and immediate postresection images to be available to the skull base surgeon. There was a significant improvement in mean (standard deviation [SD]) CT intensity in the left carotid artery postcontrast 334 HU (67 HU) (p < 10−10). The mean FRE was 1.8 mm (0.45 mm).

Conclusion Intraoperative CBCT in complex skull base procedures provides high-resolution bony detail allowing immediate assessment of complex resections. The use of IV contrast with CBCT improves the visualization of vasculature. Image-guidance based on CBCT yields registration errors consistent with standard techniques.

Key Points

Question: Is intraoperative CBCT image quality adequate for skull base surgery?


Finding: Intraoperative CBCT can provide good quality images, particularly for bony and vascular anatomy.


Meaning: Intraoperative images can be used to update the navigation system. The combined image quality and intraoperative update allow the surgeon to assess surgical resections in real time.


Meeting Presentations: A preliminary summary of this work was presented at the 5th World Congress of International Federation of Head & Neck Oncologic Societies, New York, NY, July 26–30, 2014.




Publication History

Received: 21 May 2019

Accepted: 29 August 2019

Article published online:
03 February 2020

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