Wieslaw L. Nowinski and Arumugam Thirunavuukarasuu
Functional imaging is an established neurosurgical modality for studying the brain in health and disease. Identifying numerous activation loci on many functional images and reading their underlying cortical and subcortical anatomy, coordinates, and anatomical and functional values is a tedious, time-consuming, and error-prone task. In this study the authors propose a novel approach to this problem by using an electronic brain atlas in conjunction with a locus-driven mechanism.
The Brain Atlas for Functional Imaging containing an enhanced and extended electronic version of the Talairach–Tournoux brain atlas was used for analysis. It enables loading of anatomical and functional data, correlation of these data, identification of activation loci, and their labeling with Brodmann areas, gyri, and subcortical structures by means of the atlas. The Talairach proportional grid system transformation is used to register the anatomical and functional data with the atlas. The availability of numerous tools supports this process.
A locus-driven mechanism for analysis of activation loci is implemented. Locus placement within the activation region is supported by thresholding, and its location can be further edited in three dimensions on any orthogonal plane. Once all loci are identified and edited, their labels, coordinates, and anatomical/functional values are read automatically and saved in an external file. This mechanism enables the analysis to be performed in an automated, rapid, explicit, three-dimensionally consistent, and user-friendly way.
The electronic brain atlas with locus-driven mechanism is a useful tool for localization analysis of functional images.
Wieslaw L. Nowinski, Beng Choon Chua, Ihar Volkau, Fiftarina Puspitasari, Yevgen Marchenko, Val M. Runge and Michael V. Knopp
The most severe complication of deep brain stimulation (DBS) is intracranial hemorrhage. Detailed knowledge of the cerebrovasculature could reduce the rate of this disorder. Morphological scans typically acquired in stereotactic and functional neurosurgery (SFN) by using 1.5-T (or sometimes even 3-T) imaging units poorly depict the vasculature. Advanced angiographic imaging, including 3- and 7-T 3D time-of-flight and susceptibility weighted imaging as well as 320-slice CT angiography, depict the vessels in great detail. However, these acquisitions are not used in SFN clinical practice, and robust methods for their processing are not available yet. Therefore, the authors proposed the use of a detailed 3D stereotactic cerebrovascular atlas to assist in SFN planning and to potentially reduce DBS-induced hemorrhage.
A very detailed 3D cerebrovascular atlas of arteries, veins, and dural sinuses was constructed from multiple 3- and 7-T scans. The atlas contained > 900 vessels, each labeled with a name and diameter with the smallest having a 90-μm diameter. The cortical areas, ventricular system, and subcortical structures were fully segmented and labeled, including the main stereotactic target structures: subthalamic nucleus, ventral intermediate nucleus of the thalamus, and internal globus pallidus. The authors also developed a computer simulator with the embedded atlas that was able to compute the effective electrode trajectory by minimizing penetration of the cerebrovascular system and vital brain structures by a DBS electrode. The simulator provides the neurosurgeon with functions for atlas manipulation, target selection, trajectory planning and editing, 3D display and manipulation, and electrode-brain penetration calculation.
This simulation demonstrated that a DBS electrode inserted in the middle frontal gyrus may intersect several arteries and veins including 1) the anteromedial frontal artery of the anterior cerebral artery as well as the prefrontal artery and the precentral sulcus artery of the middle cerebral artery (range of diameters 0.4–0.6 mm); and 2) the prefrontal, anterior caudate, and medullary veins (range of diameters 0.1–2.3 mm). This work also shows that field strength and pulse sequence have a substantial impact on vessel depiction. The numbers of 3D vascular segments are 215, 363, and 907 for 1.5-, 3-, and 7-T scans, respectively.
Inserting devices into the brain during microrecording and stimulation may cause microbleeds not discernible on standard scans. A small change in the location of the DBS electrode can result in a major change for the patient. The described simulation increases the neurosurgeon's awareness of this phenomenon. The simulator enables the neurosurgeon to analyze the spatial relationships between the track and the cerebrovasculature, ventricles, subcortical structures, and cortical areas, which allows the DBS electrode to be placed more effectively, and thus potentially reducing the invasiveness of the stimulation procedure for the patient.