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Preoperative Templating Before Spinal Fusion Using a Fluoroscopic Multiplanar Imaging System is as Accurate as CT Scan and Uses Substantially Less Radiation

Kepler, Christopher K. MD, MBA*; Pavlov, Helene MD; Kim, Han J. MD*; Green, Daniel W. MD, MS*; Rawlins, Bernard A. MD*

Journal of Pediatric Orthopaedics: December 2012 - Volume 32 - Issue 8 - p e67–e71
doi: 10.1097/BPO.0b013e31826bb0ed
Spine

Background: Many surgeons utilize preoperative multiplanar imaging for surgical planning before fusion surgery using pedicle screw instrumentation. Computed tomographic (CT) scan is often used but limited by non–weight-bearing images and high-ionizing radiation. The purpose of this study was to compare pedicle length and width measurements using a multiplanar fluoroscopic imaging system and CT with gross measurements to validate the accuracy of multiplanar fluoroscopic imaging and compare relative radiation exposure between techniques.

Methods: Thirteen intact cadaveric lumbar spine segments were imaged using multiplanar fluoroscopic imaging and conventional CT scan using a low-dose pediatric protocol. At each level and each imaging modality, the 26 pedicles were measured digitally for width and pedicle screw length in accordance with typical presurgical planning procedures. All images were independently measured by 3 observers. After measurement, the specimens were sectioned using a microsurgical saw to facilitate anatomic measurements using calipers. Measurements of the multiplanar fluoroscopic imaging and CT were compared with direct anatomic measurements to quantitate and compare measurement accuracy of CT and fluoroscopic imaging. At the time of image acquisition, radiation exposure from each modality was quantified to allow for comparison of radiation exposures.

Results: CT and multiplanar fluoroscopy had similar agreement with gross measurements with respect to pedicle width and length, with κ values for comparison of CT and fluoroscopy with gross measurements falling between 0.61 and 0.73. Both modalities underestimated pedicle width (by 1.9 mm for both modalities) and length (5.5 mm for CT, 6.6 mm for fluoroscopy). Interobserver reliability was higher for fluoroscopy versus CT. High-dose fluoroscopic imaging used 31% of the radiation exposure for CT.

Conclusions: Multiplanar fluoroscopic imaging provides comparable diagnostic preoperative planning to CT scan in an experimental cadaveric model. The use of multiplanar fluoroscopic imaging resulted in between 69% and 85% less radiation exposure than conventional CT scan using pediatric settings.

Clinical Evidence: This study demonstrates similar results from simulated preoperative templating using fluoroscopic imaging compared with CT scan but with less radiation exposure.

Departments of *Orthopaedic Surgery, Spine & Scoliosis Service

Radiology & Imaging, Hospital for Special Surgery, New York, NY

H.P. receives institutional research support from Phillips Inc. None of the authors received financial support specific to this investigation.

The authors declare no conflict of interest.

Reprints: Christopher K. Kepler, MD, MBA, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021. E-mail: chris.kepler@gmail.com.

© 2012 Lippincott Williams & Wilkins, Inc.