Usability study of human-computer interfaces for 3D model manual registration in augmented reality application for surgery

Augmented reality (AR) is becoming essential in several surgical specialities [1]. Fusing patient-specific preoper- ative information, typically 3D models extracted from CT scans or MRI, on the real-time surgical images allows the surgeon to have detailed information on the anatomical structure of the surgical target intra- operatively. As stated in [2] and [3], an AR system’s first step consists of an initial rigid registration of the 3D models on the surgical image. Most of the approaches are manual or semi-automatic. While the latter exploits physical landmarks on the tissue or 3D surface features, the manual approach requires Human- Computer Interfaces (HCI) to manipulate the models. The choice of the HCI is fundamental to develop an easy-to-use application with a short learning curve. In fact, the way the manual registration is performed can impact the users’ physical and mental stress, influencing their final performances. This paper presents a human-centred usability study that aims to evaluate two modern HCI devices com- monly proposed for 3D model manipulation in surgical augmented reality applications, i.e., the SpaceMouse® and UltraLeap® . Accordingly, a software interface was developed to allow the manipulation of 3D models in a minimally invasive partial nephrectomy scenario. Subjects were asked to perform a rigid manual registration of a kidney’s 3D model on the image of the real kidney. Quantitative and qualitative evaluation was performed to assess the cognitive and physical load imposed on the operators, which can support an informed selection of HCI to maximize system usability and operator perfor- mance. These trials were performed under study protocol 229/2019 - ID 4621, approved by the Regional Ethics Committee of Liguria (Italy).