A Tracked High-Resolution Ultrasound Endoscope for Minimally Invasive Brain Surgery

We have developed a novel intraoperative imaging adjunct to address limitations in neurosurgical guidance technology: a miniature, high-resolution, tracked ultrasound (US) imaging endoscope. This report describes the fabrication and preliminary testing of the device, which aims to enhance neurosurgery by providing precise, real-time visualization of the brain within narrow surgical pathways.

The work has 2 components: (1) the development and clinical validation of the US endoscope and (2) its integration with a surgical navigation system (SNS), with tracking validated in a brain phantom. A miniature (3.8 × 4 mm cross-section) 30 MHz phased array with 64 elements was developed, and probe performance and safety were tested. Investigational testing of the untracked imaging probe was performed in 3 adult neurosurgery cases (2 glioblastoma resections and 1 aneurysm clipping). B-mode and Doppler imaging data were collected to explore the probe's ability to visualize anatomy intraoperatively. The probe was integrated with a commercial SNS and tested in a brain phantom containing a simulated tumor and landmark. Agreement between the landmark location based on B-mode US and navigated 3-dimensional T1-weighted MRI was characterized.

The probe demonstrated axial and lateral resolutions of 38 and 113 µm, respectively. During tumor resection, it differentiated tumor from healthy tissue and identified residual tumor missed by conventional surgical guidance. Key structures were also visualized during aneurysm surgery. The US probe was successfully integrated with a SNS. When this combined system was tested in a brain phantom, there was good agreement between tumor boundaries in navigated MRI and US images, with the apparent landmark location agreeing within µ = 2.90 mm over 25 trials.

This first-of-its-kind imaging system shows potential as a novel adjunct for neurosurgical guidance. Further clinical testing is needed to fully validate its efficacy.