Towards an MRI-Conditional Robot for Intracerebral Hemorrhage Evacuation

Abstract

Stroke is the second leading cause of death worldwide, causing over six million deaths in 2019 [1]. Intracerebral hemorrhage (ICH), a subcategory of hemorrhagic strokes, accounts for 20% of total stroke deaths, with a one year mortality rate as high as 65% [2]. Forty percent of these deaths occur within two days of symptom onset [2], suggesting a benefit to early hemorrhage evacuation following clinical decompensation [3]. Despite the need for urgency, “watchful waiting” or conservative management has been a common treatment modality due to the potential cortical disruption and brain shift associated with large craniotomies [3]. However, in recent years, minimally invasive surgery has proven to be a safer alternative to larger, open craniotomies for hemorrhagic clot evacuation [3] and is an increasingly accepted method of treatment for patients with a deep-seated hematoma 30-50 mL in volume [4]. Unfortunately, minimally invasive methods are complicated by lack of adequate visualization, which is necessary to account for brain shift and deformation during the evacuation procedure. In recent studies, there has been a push for coupling minimally invasive robotic interventions with different intraprocedural visualization techniques. Using the concentric tube robot (CTR), several groups have used interventional CT [5], endoscopic cameras [6], and interventional MRI [7] to guide minimally invasive neurosurgical procedures. However, each imaging modality comes with corresponding pitfalls. CT applies ionizing radiation to the patient, requiring a cost-benefit balance between dynamic visualization and ionizing radiation exposure. Endoscopic cameras possess a limited field-of-view, preventing full dynamic brain visualization. MRI, though it provides superior imaging quality without a detrimental impact on the patient, is restricted by the inability to use ferromagnetic materials, i.e., magnets, steel, iron, etc., and the reduction in image quality by non-ferromagnetic metals, such as nitinol. In this paper, we build upon our work in [7], aiming to ameliorate the reduction of imaging quality associated with the use of metallic materials by developing a plastic MRI-compatible robotic system for MRI-guided ICH removal. This paper presents the first use of off-the-shelf plastic tubes for CTR, and characterizes the robot’s accuracy, MRI-compatibility, and evacuation feasibility for ICH evacuation in phantom trials.