Sonification as a reliable alternative to conventional visual surgical navigation

Abstract

Despite the undeniable advantages of image-guided surgical assistance systems in terms of accuracy, such systems have not yet fully met surgeons' needs or expectations regarding usability, time efficiency, and their integration into the surgical workflow. On the other hand, perceptual studies have shown that presenting independent but causally correlated information via multimodal feedback involving different sensory modalities can improve task performance. This article investigates an alternative method for computer-assisted surgical navigation, introduces a novel four-DOF sonification methodology for navigated pedicle screw placement, and discusses advanced solutions based on multisensory feedback. The proposed method comprises a novel four-DOF sonification solution for alignment tasks in four degrees of freedom based on frequency modulation synthesis. We compared the resulting accuracy and execution time of the proposed sonification method with visual navigation, which is currently considered the state of the art. We conducted a phantom study in which 17 surgeons executed the pedicle screw placement task in the lumbar spine, guided by either the proposed sonification-based or the traditional visual navigation method. The results demonstrated that the proposed method is as accurate as the state of the art while decreasing the surgeon's need to focus on visual navigation displays instead of the natural focus on surgical tools and targeted anatomy during task execution.

Figure 1

Three cross-sectional views of the CT from the spine phantom model, including the corresponding errors ($e_x,e_y,e_{\varphi },e_{\delta }$). The target and tool are visualized in green and red, respectively. (a) Corresponds to the coronal view visualizing, $e_x$ and $e_y$ projected on the $P_{\mathit{entry}}$; (b) represents the axial view visualizing $e_{\varphi }$; and (c) visualizes the sagittal view including $e_{\delta }$.

Figure 2

Four DOF alignment model with four phases, initial phase (IP), entry point phase (EP), angle phase (AP), and final phase (FP). EP and AP are two interactive phases with continuous mappings, whereas IP and FP are the static phases with constant mappings.

Figure 3

Illustration of the thresholds for transition between phases. (a) the circles demonstrate thresholds for the transition between IP, EP and AP; (b) the cones represent the thresholds for transition between AP and FP.

Figure 4

The experiment setup, (a) the phantom covered with Play-Doh, (b) task assisted with visualization, (c) task assisted with sonification.

Figure 5

The mean (CT) error of angle (Top), entry point (Bottom) over expertise groups. The white dots in the middle of box plots represent the mean.

Figure 6

The mean (CT) error of angle on the left and entry point on the right, per spinal levels. The white dots in the middle of box plots represent the mean.

Figure 7

Alignment time of the 1st. and 2nd. executions over the spinal levels.