Use of Intraoperative Ultrasound to Improve Neuronavigation for Resection of Skull Base Tumors

Neuronavigation using integrated multimodal imaging is an invaluable tool for targeted and safe brain tumor resection. Image guidance with integrated neuronavigation can be complicated by pathological changes prior to surgery, intraoperative brain shift, or other intraoperative changes to the surgical equipment or anatomy of the patient. These changes can render preprocedural imaging unreliable and may lead to surgical error. Intraoperative magnetic resonance imaging (MRI) can be used; however, it is time-consuming, expensive, and not widely available. The use of intraoperative navigation augmented with ultrasound combined with preoperative MRI has can be a feasible option due its accessibility and ability to provide surgeons with real time, dynamic neuronavigation. We present this technique and our experience with 12 consecutive patients that underwent tumor resection guided by intraoperative ultrasound integrated with neuronavigation to assist with resection of skull base tumors.

Preoperative MRI imaging was integrated with intraoperative CT taken in the operating room using Airo and BrainLab neuronavigation system (BrainLab AG). Image fusion is done between the MRI and CT. Three-dimensional ultrasound guidance was introduced and synchronized to the neuronavigation system for a variety of tasks across our all patients prior to dural opening as well as tumor resection. The 3D ultrasound was repeated throughout the case and allowed for live, dynamic visualization during further debulking of the tumor ([Fig. 1]). Intraoperative ultrasound couple with neuronavigation was also used to confirm adequate resection and decompression of the tumor, as well as confidently identify delicate structures that were adherent to, encapsulated in, or surrounding the area of resection. Use of color Doppler ultrasound can also be included.

Of the twelve tumors resected, six were WHO grade I meningiomas, two vestibular schwannomas, one medulloblastoma, one neurosarcoidosis lesion, one metastatic carcinoma, and one diffuse large B cell lymphoma. Seven tumors were infratentorial. Approximate tumor volume ranged from 12.1 to 171.4 cm³. All of the cases concluded without any immediate postoperative complications. Gross total resection was achieved in eight cases. An illustrative case of a patient with a petroclival meningioma that was resected via right transpetrosal approach is presented in [Figs. 2] [3].

The use of intraoperative ultrasound provides a live, dynamic view of skull base tumors which largely minimizes the inaccuracies that occur from brain shift. Additional research is required to corroborate the potential benefit and need for the integration of ultrasound navigation.

Fig. 2 Preoperative MRI fused with intraoperative CT.

Fig. 3 Intraoperative 3D ultrasound merged with neuronavigation to augment live resection. A. Pre-resection. B. During resection.

Publication History

Article published online:
01 February 2023