Table 1.

Advantages and disadvantages of using the O-arm during DBS procedures

Advantages
–	The O-arm is a C-arm-based flat panel volume CT and combines both CT and fluoroscopy function. This is an advantage compared to intraoperative multidetector systems, as millimetric adjustments in the dorsoventral plane could be verified by using fluoroscopy (which is more easily done than using repetitive iCT).
–	Image acquisition, for 3D, is around 13 s, so that the surgical time is not notably prolonged. Acquisition time is considerably faster compared to intraoperative MRI [20].
–	High spatial resolution of flat-panel iCT enables direct evaluation of microelectrode trajectories. While this was not the primary goal of our study, we found the possibility of evaluating both microelectrode placement and movement highly useful.
–	Using a high-definition optical enhancement mode enables detecting occurrence of a (small) hematoma in the trajectory course.
–	Different position settings can be saved by the O-arm, which allows simple switching between the established position for surgical proceedings versus that for performing imaging.
–	Although not implemented by our group, an interesting application of iCT is to replace conventional preoperative stereotactic CT. The field of view is modified in the latest version of the O-arm so that performing registration series using the Leksell frame is enabled.
Disadvantages
–	Contrast resolution with standard settings is insufficient for full view of intracranial structures as brain parenchyma and ventricles which can be used to evaluate co-registration or brain shift.
–	The O-arm is quite large, this requires careful planning to maintain field sterility and provide adequate surgical access.