Enhancing intraoperative pedicle screw planning accuracy via diffusion-based synthetic CT

Intraoperative cone beam computed tomography (CBCT) is critical for pedicle screw planning; however, image quality is frequently compromised by artifacts and low contrast, potentially leading to adverse clinical outcomes. To address these limitations, we propose the Spatiotemporal Adaptive Warm-Start Diffusion Model (STADW-M), a novel framework aimed to generate high-quality synthetic CT (sCT) images from CBCT data, thereby enhancing surgical precision. The STADW-M integrates an Artifact-Aware Adaptive Diffusion Module to mitigate localized artifact distributions and a Dually-Guided Structural Consistency Module to preserve anatomical integrity. Furthermore, we employ a CBCT Warm-Start strategy alongside composite loss functions to optimize textural fidelity and accelerate model convergence. Quantitative experiments demonstrated significant improvements over original CBCT images: with RMSE decreased from 890.1 to 152.9 HU, MAE decreasing from 859.7 to 102.6 HU, and PSNR increased from 13.6 to 27.9 dB. Crucially, the generated sCTs maintained high anatomical consistency with reference CTs. In clinical validation, automated screw planning based on sCTs achieved a 100% Grade A standard, with 94.7% of screws placed without cortical breach and 5.3% exhibiting only minor (<2 mm) erosion. The proposed method effectively synthesizes high-quality CT images, preserving vertebral anatomy and significantly improving the accuracy and safety of intraoperative pedicle screw planning.