Clinical testing of an alternate method of inserting bone-implanted fiducial markers

Ramya Balachandran, Mark A. Fritz, Mary S. Dietrich, Andrei Danilchenko, Jason E. Mitchell, Veronica L. Oldfield, Wendy W. Lipscomb, J. Michael Fitzpatrick, Joseph S. Neimat, Peter E. Konrad, Robert F. Labadie

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Purpose:    The purpose of the study was to test clinically a depth-release drive system, the PosiSeat™, versus manual insertion (pilot hole followed by manual screwing until tactile determined correct seating) for implanting fiducial markers into the bone.

Background:    Deep brain stimulation (DBS) surgery utilizes image guidance via bone-implanted fiducial markers to achieve the desired submillimetric accuracy and to provide means for attaching microstereotactic frames. For maximal benefit, the markers must be inserted to the correct depth since over-insertion leads to stripping and under-insertion leads to instability.

Methods:    With institutional review board approval, the PosiSeat™ was used to implant markers in 15 DBS patients (57 fiducials). On post-insertion CT scans, the depth of the gap between the shoulder of the fiducial markers and the closest bone surface was measured. Similar depth measurements were performed on the CT scans of 64 DBS patients (250 fiducials), who underwent manual fiducial insertion.

Results:    Median of shoulder-to-bone distance for PosiSeat™ and manual insertion group were 0.03 and 1.06 mm, respectively. Fifty percent of the fiducials had the shoulder-to-bone distances within 0.01–0.09 mm range for the PosiSeat group and 0.04–1.45 mm range for the manual insertion group. These differences were statistically significant.

Conclusions:    A depth-release drive system achieves more consistent placement of bone-implanted fiducial markers than manual insertion.

Original languageEnglish
Pages (from-to)913-920
Number of pages8
JournalInternational journal of computer assisted radiology and surgery
Issue number5
StatePublished - Sep 28 2014

Bibliographical note

Funding Information:
Acknowledgments The project described was supported by Award Numbers R01DC008408 from the National Institute on Deafness and Other Communication Disorders. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute on Deafness and Other Communication Disorders or the National Institutes of Health. Human subjects participation statements All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008 (5). Informed consent was obtained from all patients for being included in the study.

Funding Information:
For each patient undergoing fiducial marker placement, a CT scan with voxel size approximately 0.59 × 0.59 × 0.75 mm was acquired after fiducial placement as standard of care. The scans of patients were analyzed with 3D Slicer Version 3.4, an open-source image analysis tool, developed by National Alliance for Medical Image Computing (NAMIC) and funded by the National Institutes of Health (NIH) (Grant U54 EB005149). Additional coding was developed to specifically localize fiducial markers and measure the shortest distance from the underside shoulder of the fiducial to the closest skull surface (Fig. 2). This distance, called the shoulder-to-bone distance, was measured for all fiducials in all patients in the study.

Publisher Copyright:
© 2014, CARS.


  • Computerized tomography
  • Deep brain stimulation
  • Fiducial markers
  • Image-guided surgery
  • PosiSeat
  • Stereotactic surgery

ASJC Scopus subject areas

  • Surgery
  • Biomedical Engineering
  • Radiology Nuclear Medicine and imaging
  • Computer Vision and Pattern Recognition
  • Computer Science Applications
  • Health Informatics
  • Computer Graphics and Computer-Aided Design


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