Intraoperative CT as a registration benchmark for intervertebral motion compensation in image-guided open spinal surgery

Abstract

Purpose An accurate and reliable benchmark of registration accuracy and intervertebral motion compensation is important for spinal image guidance. In this study, we evaluated the utility of intraoperative CT (iCT) in place of bone-implanted screws as the ground-truth registration and illustrated its use to benchmark the performance of intraoperative stereovision (iSV). Methods A template-based, multi-body registration scheme was developed to individually segment and pair corresponding vertebrae between preoperative CT and iCT of the spine. Intervertebral motion was determined from the resulting vertebral pair-wise registrations. The accuracy of the image-driven registration was evaluated using surface-to-surface distance error (SDE) based on segmented bony features and was independently verified using point-to-point target registration error (TRE) computed from bone-implanted mini-screws. Both SDE and TRE were used to assess the compensation accuracy using iSV. Results The iCT-based technique was evaluated on four explanted porcine spines (20 vertebral pairs) with artificially induced motion. We report a registration accuracy of 0.57 ± 0.32 mm (range 0.34–1.14 mm) and 0.29 ± 0.15 mm (range 0.14–0.78 mm) in SDE and TRE, respectively, for all vertebrae pooled, with an average intervertebral rotation of 4.9° ± 1.2° (range 1.5°–7.9°). The iSV-based compensation accuracy for one sample (four vertebrae) was 1.32 ± 0.19 mm and 1.72 ± 0.55 mm in SDE and TRE, respectively, exceeding the recommended accuracy of 2 mm. Conclusion This study demonstrates the effectiveness of iCT in place of invasive fiducials as a registration ground truth. These findings are important for future development of on-demand spinal image guidance using radiation-free images such as stereovision and ultrasound on human subjects.

Intraoperative Computed Tomography-Based Navigation with Augmented Reality for Lateral Approaches to the Spine

“…A user-independent automatic registration concept applying intraoperative CT was recently reported and showed a mean target registration error (TRE) for spinal procedures of 0.86 ± 0.28 mm [ 20 ]. Our results correspond well to these and to results of the spine phantom studies comparing intraoperative registration to bone surface registration or to bone-implanted miniscrews, which showed TREs of 0.74 and 0.14–0.78 mm, respectively [ 23 , 24 ]. Radiation-free alternatives for registration are surface-matching and point-to-point registration using a pointer or settings using ultrasound to delineate the shape of the bony structures of the spine for registration; however, these are considerably more inaccurate than automatic iCT-based registration [ 17 , 25 , 26 ].…”

Reliable navigation registration in cranial and spine surgery based on intraoperative computed tomography

“…Our results for spine surgery with a mean TRE of 0.80 ± 0.28 mm correspond well to the results of a phantom study for spine registration that compared automatic intraoperative imaging-based registration and bone surface registration (0.74 mm vs 1.1 mm), 32 as well as to a spine phantom experiment using iCT and bone-implanted miniscrews with a TRE that ranged from 0.14 to 0.78 mm. 14…”

Modalities for image- and molecular-guided cancer surgery

“…Bone anatomy well visualized but limited on the lesion itself 54 . Radiation exposure 29 Cirrhosis and steatosis (induced by chemotherapy); imaging of cirrhotic or steatotic liver can be improved by using contrast agent 27,28 . Lack of anatomical orientation 23 Sensitivity, specificity of system Increases with field strength 19,25,55 Specificity > 90%, but sensitivity only 60% 20…”