Mobile intraoperative CT-assisted frameless stereotactic biopsies achieved single-millimeter trajectory accuracy for deep-seated brain lesions in a sample of 7 patients

Abstract

Background Brain biopsies are crucial diagnostic interventions, providing valuable information for treatment and prognosis, but largely depend on a high accuracy and precision. We hypothesized that through the combination of neuronavigation-based frameless stereotaxy and MRI-guided trajectory planning with intraoperative CT examination using a mobile unit, one can achieve a seamlessly integrated approach yielding optimal target accuracy. Methods We analyzed a total of 7 stereotactic biopsy trajectories for a variety of deep-seated locations and different patient positions. After rigid head fixation, an intraoperative pre-procedural scan using a mobile CT unit was performed for automatic image fusion with the planning MRI images and a peri-procedural scan with the biopsy cannula in situ for verification of the definite target position. We then evaluated the radial trajectory error. Results Intraoperative scanning, surgery, computerized merging of MRI and CT images as well as trajectory planning were feasible without difficulties and safe in all cases. We achieved a radial trajectory deviation of 0.97 ± 0.39 mm at a trajectory length of 60 ± 12.3 mm (mean ± standard deviation). Repositioning of the biopsy cannula due to inaccurate targeting was not required. Conclusion Intraoperative verification using a mobile CT unit in combination with frameless neuronavigation-guided stereotaxy and pre-operative MRI-based trajectory planning was feasible, safe and highly accurate. The setting enabled single-millimeter accuracy for deep-seated brain lesions and direct detection of intraoperative complications, did not depend on a dedicated operating room and was seamlessly integrated into common stereotactic procedures.

Feasibility and Accuracy of Robot-Assisted, Stereotactic Biopsy Using 3-Dimensional Intraoperative Imaging and Frameless Registration Tool

“…2,24 The mean target error of robot-assisted stereotactic biopsy previously reported with other robotic-assisted systems, ranging from 0.72 to 1.13 mm, is in line with the present results (mean of 0.7 ± 0.7 mm). 16,18,25 In this series, the operative time (mean of 59 min) was longer than reported series using other robotic-assisted systems without intraoperative imaging 16,18 because of the time required to obtain intraoperative imaging, but shorter compared with other series using intraoperative imaging. 18,25 This is in part due to different definitions of operative time and to the different frequencies of intraoperative frozen sections.…”

“…In this series, the operative time (mean of 59 min) was longer than reported series using other robotic-assisted systems without intraoperative imaging 16,18 because of the time required to obtain intraoperative imaging, but shorter compared with other series using intraoperative imaging. 18,25 This is in part due to different definitions of operative time and to the different frequencies of intraoperative frozen sections. Intraoperative imaging allows for verification of the correct location of the actual biopsy trajectory and sampling and a post hoc measurement of the actual accuracy.…”

“…2,24 The mean target error of robot-assisted stereotactic biopsy previously reported with other robotic-assisted systems, ranging from 0.72 to 1.13 mm, is in line with the present results (mean of 0.7 ± 0.7 mm). 16,18,25…”

“…Intraoperative imaging allows for verification of the correct location of the actual biopsy trajectory and sampling and a post hoc measurement of the actual accuracy. 25 The time saved in comparison with the previous robot-assisted workflow was due to the use of the new frameless registration module and of 3D intraoperative imaging. The procedure aimed to be as accurate as possible, so the reduction of the operative time was not an objective but underlined the progresses of the robotic assistance in neurosurgery.…”

Advances, technological innovations, and future prospects in stereotactic brain biopsies

“…One of the shortcomings of this technique is the double radiation exposure in one surgery, but it can be aided by the use of a low-dose-irradiated iCT. A similar surgical workflow using intraoperative verification with a mobile CT unit in combination with frameless neuronavigation-guided stereotaxy and preoperative MRI-based trajectory planning confirmed targeting accuracy with minimal radial trajectory deviation [ 5 ].…”