Known‐component 3D image reconstruction for improved intraoperative imaging in spine surgery: A clinical pilot study

Purpose Intraoperative imaging plays an increased role in support of surgical guidance and quality assurance for interventional approaches. However, image quality sufficient to detect complications and provide quantitative assessment of the surgical product is often confounded by image noise and artifacts. In this work, we translated a three‐dimensional model‐based image reconstruction (referred to as “Known‐Component Reconstruction,” KC‐Recon) for the first time to clinical studies with the aim of resolving both limitations. Methods KC‐Recon builds upon a penalized weighted least‐squares (PWLS) method by incorporating models of surgical instrumentation (“known components”) within a joint image registration–reconstruction process to improve image quality. Under IRB approval, a clinical pilot study was conducted with 17 spine surgery patients imaged under informed consent using the O‐arm cone‐beam CT system (Medtronic, Littleton MA) before and after spinal instrumentation. Volumetric images were generated for each patient using KC‐Recon in comparison to conventional filtered backprojection (FBP). Imaging performance prior to instrumentation (“preinstrumentation”) was evaluated in terms of soft‐tissue contrast‐to‐noise ratio (CNR) and spatial resolution. The quality of images obtained after the instrumentation (“postinstrumentation”) was assessed by quantifying the magnitude of metal artifacts (blooming and streaks) arising from pedicle screws. The potential low‐dose advantages of the algorithm were tested by simulating low‐dose data (down to one‐tenth of the dose of standard protocols) from images acquired at normal dose. Results Preinstrumentation images (at normal clinical dose and matched resolution) exhibited an average 24.0% increase in soft‐tissue CNR with KC‐Recon compared to FBP (N = 16, P = 0.02), improving visualization of paraspinal muscles, major vessels, and other soft‐tissues about the spine and abdomen. For a total of 72 screws in postinstrumentation images, KC‐Recon yielded a significant reduction in metal artifacts: 66.3% reduction in overestimation of screw shaft width due to blooming (P