Evaluation of errors influencing accuracy in image-guided neurosurgery

Abstract

Neurosurgeons sometimes find it difficult to locate tumors precisely during microsurgery, particularly tumors located in the brain parenchyma because of the absence of boundaries in this region. Image-guided neurosurgical techniques conducted with the help of neuronavigation systems have been developed and have gained importance recently. Accuracy is vital during image-guided neurosurgery. We used a phantom to evaluate the errors introduced during navigation. The three errors evaluated were skin-shift, marker-gap, and table-rotation errors. The skin-shift error occurs if the fiducial markers positioned on the scalp move when the head is fixed to a head holder with head pins. The marker-gap error occurs when the marker ball is positioned incorrectly in the marker socket. The table-rotation error occurs when the operating table is rotated for obtaining an intraoperative MR image and then returned to its original position. Our results indicated that skin shift decreased the navigation accuracy by an error of more than 4 mm, and the gap between the marker ball and the socket resulted in a decrease in navigation accuracy by an error of more than 5 mm. The table-rotation error was found to be negligible. The errors can be avoided by ensuring that the fiducial markers are positioned appropriately on the scalp and the marker ball is fitted well in the marker socket. A phantom is useful for evaluating accuracy, particularly for evaluating errors intrinsic to different operating rooms. Periodic quality assurance by use of a phantom in each operating room might aid in maintaining the accuracy of neuronavigation.

Skin shift and its effect on navigation accuracy in image-guided neurosurgery

“…In addition, the results indicate that skin shift reduces the navigation accuracy. The results of this study confirm those of our previous phantom study [1].…”

“…However, it is difficult to identify tumor boundaries with the use of an operative microscope only. The development of neuronavigation systems in recent years has enabled surgeons to comprehend the positional relationship between tumors and normal tissue [1]. Therefore, navigation systems are very useful in the resection of tumors located near the functional areas [2,3].…”

“…As mentioned earlier, the navigation accuracy based on preoperative MRI may be influenced by skin shift. In a previous study, we assessed the effect of skin shift by using a phantom [1]. We positioned two of the markers 5 mm behind their original position and measured the navigation accuracy.…”

Neuronavigated microvascular Doppler sonography for intraoperative monitoring of blood flow velocity changes during aneurysm surgery – A feasible monitoring technique

“…Different tools are used to avoid vessel compromise during aneurysm surgery, such as motor evoked potential monitoring, which documents ischemia as a sequel of insufficient blood flow, intraoperative digital subtraction angiography and endoscopic or microscopic indocyanine green videoangiography, which visualizes blood flow, and iMDS to measure BFV [8][9][10][11][12][13]. However, the measured BFV depends both on the insonated vessel segment as well as on the insonation angle.…”

A three-dimensional MRI study of variations in central sulcus location in 40 normal subjects

“…2 Intraoperative neuronavigation is valuable for the localization of the eloquent structures of the brain in individuals because it is accurate to within millimeters. 20 The functional measurements produced by 7 Tesla MRI with 1 mm isotropic resolution 19 would yield additional reliable intraoperative guidance. Our finding that the right SRP is located more anteriorly than the left SRP is of interest from a neuroanatomical and neurodevelopmental perspective because it points to an asymmetry in human brain morphology.…”