Augmented reality visualisation using an image overlay system for MR-guided interventions: Technical performance of spine injection procedures in human cadavers at 1.5 Tesla

Objectives: To prospectively assess the technical performance of an augmented reality system for MR-guided spinal injection procedures. Methods: The augmented reality system was used with a clinical 1.5-T MRI system. A total of 187 lumbosacral spinal injection procedures (epidural injection, spinal nerve root injection, facet joint injection, medial branch block, discography) were performed in 12 human cadavers. Needle paths were planned with the Perk Station module of 3D Slicer software on high-resolution MR images. Needles were placed under augmented reality MRI navigation. MRI was used to confirm needle locations. T1-weighted fat-suppressed MRI was used to visualise the injectant. Outcome variables assessed were needle adjustment rate, inadvertent puncture of non-targeted structures, successful injection rate and procedure time. Results: Needle access was achieved in 176/187 (94.1%) targets, whereas 11/187 (5.9%) were inaccessible. Six of 11 (54.5%) L5-S1 disks were inaccessible, because of an axial obliquity of 30Ëš (27Ëš-34Ëš); 5/11 (45.5%) facet joints were inaccessible because of osteoarthritis or fusion. All accessible targets (176/187, 94.1%) were successfully injected, requiring 47/176 (26.7%) needle adjustments. There were no inadvertent punctures of vulnerable structures. Median procedure time was 10.2min (5-19min). Conclusions: Image overlay navigated MR-guided spinal injections were technically accurate. Disks with an obliquity ≥27Ëš may be inaccessible. Key Points: • Augmented reality technology facilitates MR-guided spine injections. • Patient and operator exposure to ionising radiation can be obviated. • MR imaging guidance enabled the procedure without need of a dedicated interventional MRI system. • Various MR-guided spine injection procedures using augmented reality are technically accurate. • Augmented reality has potential to simplify the workflow of MR-guided spine injections.