Neurosurgery hopes to maximize the removal of lesions and prolong the life of patients, but also requires maintaining a good quality of life for patients. With the development of computer technology and magnetic resonance technology, some scholars have combined fiber bundle tracer imaging technology with neuronavigation system and achieved good results. 1, magnetic resonance brain diffusion tensor imaging technique and white matter fiber bundle tracer imaging The so-called diffusion refers to the random motion of molecules, i.e. Brownian motion. If water molecules have the same diffusion ability in all directions, it is called isotropic. Due to the complexity of the tissue structure of living organisms, dispersion in vivo is a three-dimensional process, and the direction and distance of dispersion in all directions within the imaging voxel cannot be the same, which is called anisotropy. The so-called tensor is a physical and engineering concept used to represent the tension within a series of 3D vector entities, and the anisotropic diffusion process of each voxel in the white matter of the brain can be represented by a tensor. Magnetic resonance diffusion tensorimaging (DTI) is a technique to observe the anisotropy of water molecule dispersion by varying the direction of the diffusion gradient susceptibility pulse in 3D space based on conventional diffusion imaging. It uses multiple parameters and data processing to reflect quantitative and directional changes in diffusion within the imaging voxels and is uniquely superior in showing white matter fibers in the brain [1,2]. Within the central nervous system, structures such as cell membranes, axonal membranes, and cytoskeletons restrict the movement of water molecules, and in the white matter, diffusion perpendicular to the direction of nerve fibers is slower than that parallel to the direction of nerve fibers due to the restriction of structures such as myelin sheaths and cell membranes, i.e., it shows anisotropy [3,4]. To show this anisotropy in tissues, the DTI technique was introduced. It is a method that can effectively measure the degree of dispersion of water molecules in different directions in anisotropic tissues, thereby showing how tightly the white matter fiber bundles travel and are arranged [4]. there are two types of quantitative parameters in DTI, the first is the average dispersion rate, which represents the size or degree of dispersion of water molecules within a given element. The second category is the anisotropy index, reflecting the directionality of water molecules dispersion, the most commonly used anisotropy index is partial anisotropy (fractionalanisotropy, FA), FA refers to the ratio of the anisotropic component of the dispersion tensor to the entire dispersion tensor. In a completely isotropic medium, FA = 0, and in a cylindrically symmetric anisotropic medium, FA approaches 1. FA values are sensitive indicators of whether and to what extent white matter fiber bundles are damaged, and higher values suggest better tissue orientation and better fiber bundle adhesion [4,5]. White matter fiber bundle tracer imaging is a method to map white matter fiber bundles based on magnetic resonance diffusion tensor imaging, and is the only method that can map human white matter fiber bundles in vivo, which is of great value in preoperative planning and guiding surgery in neurosurgery. There are currently two main techniques for 3D white matter fiber bundle tracer imaging, namely tensor field-based algorithms and energy minimization algorithms. The former, the most commonly used algorithm, is the linear extension technique, which is the main algorithm currently used in clinical applications and directly utilizes the tensor information within each voxel for each step of extension. The simple linear extension technique connects each voxel on the basis of a discrete coding field, but its extension between voxels is limited to eight adjacent voxels and is therefore unfavorable for white matter fiber bundle display. The continuous tracer fiber assignment technique is its improved algorithm that allows smoother white matter fiber tracing and more reliable results [1]. The continuous tracer fiber assignment technique reconstructs fiber bundles by tracing the local vector information of each voxel, starting from the seed voxel and extending linearly in the forward and backward directions. This step is repeated until the tracing reaches a voxel with an FA value less than a set threshold and/or the angle between the two main eigenvectors is greater than a set angle [6,7]. Tracer imaging of white matter fiber tracts can show the anatomical relationship between the lesion and the adjacent white matter, which helps neurosurgeons to maximize the resection of the lesion without damaging the surrounding conduction tracts [7-14].Mori et al [12] classified the involvement of white matter fibers by brain tumors into four forms decreased, suggesting that the peritumoral fiber bundles remain intact and can be preserved intraoperatively. 2. The white matter fiber bundles are normal in position and orientation, but FA is significantly reduced. This form is often seen in areas of vasogenic edema, and the exact mechanism is not known. 3, Significantly reduced FA with abnormal color on the color directional map, probably due to an invasive tumor disrupting the directionality of the fiber bundles causing a change in color pattern on the directional map. Complete isotropic diffusion, and thus failure to confirm the fiber bundles on color directional maps, represents complete destruction of the fiber bundles by the tumor. These manifestations can be present alone or in combination. 2. Fiber bundle tracer imaging navigation technique Neuronavigation technique is a frameless stereotactic system that has emerged in the last 20 years. With the development of computer, radio and signal science and other related disciplines, the neuronavigation technique has been improved to form a true real-time surgical planning and navigation tool that can display surgical instruments, target structures and pathways precisely on the reconstructed 3D images. The continuous development of modern imaging techniques has provided the neurosurgeon with the relationship between the lesion and surrounding brain structures with specific functions, and PositronEmissionTomographyPET, functional magnetic resonance imaging and magnetoencephalography have been gradually applied to neuronavigation systems to form functional neurosurgical navigation [15]. However, although these techniques help to localize functional areas such as motor, sensory and speech, they cannot provide the relationship between intracerebral lesions and peripheral conduction tracts, and have some limitations in clinical applications. Magnetic resonance brain diffusion tensor imaging and white matter fiber bundle tracer imaging can reflect the three-dimensional conduction direction of nerve fibers and show their travel direction and path through color markings, which can be applied to neurosurgical navigation systems to enable surgeons to plan preoperatively and refer to the direction of white matter fiber bundles intraoperatively for safer and more effective surgery, and combined with real-time intraoperative electrophysiological monitoring, can significantly improve the protection of brain function [8,9, 11]. Initial attempts to consider white matter fiber tracts in navigation systems applied diffusion-weighted imaging by calculating diffusion tensor data plus orientation information to obtain color-coded FA maps, but this method is time-consuming and relies heavily on the user’s anatomical knowledge rather than just the patient’s imaging data, which is prone to human error [10]. The application of white matter fiber bundle tracer imaging reduces human error to some extent. Nimsky et al [10] applied fiber bundle tracer imaging navigation technique to treat 16 patients, including 3 cases of cavernous hemangioma, 13 cases of glioma, 14 cases involving cone bundles, and 2 cases involving optic radiation, with good results. 3 cases experienced postoperative mild paralysis, of which 2 cases recovered completely, and fiber bundle tracer imaging The time taken for fiber bundle tracer imaging was about 10 minutes. For the fiber bundle tracer imaging results, the differences between the five imaging sessions of the same operator and the five different operators were within a small range, and the resulting imaging had good overlap, indicating that the human error of fiber bundle tracer imaging is very small, and the authors concluded that fiber bundle tracer imaging can be routinely used in navigational surgery and has wide value. Intraoperative magnetic resonance imaging and intraoperative ultrasonography can help correct for brain drift, but both are time-consuming and intraoperative magnetic resonance is not yet widely available. Intraoperative electrophysiological monitoring is also a commonly used technique for neuroprotection in current neurosurgery [16,17], and the functional areas of the cortex and major subcortical fibers can be identified by intraoperative electrophysiological monitoring; however, identifying fiber tracts by direct electrical stimulation may lead to postoperative functional deficits due to the excessive extent of resection, and applying the technique of topographic map of subcortical fiber electrical stimulation, the subcortical conduction pathways should be within a distance of This can lead to an increased incidence of dysfunction, and in one study it was found that in 50% of patients the conduction pathways were not detected [10,18]. One of the difficulties of the direct fiber electrical stimulation topography technique is to find the appropriate stimulation point. In addition, the constant intraoperative search and stimulation of the fiber bundle requires interruption of the surgical procedure and prolongs the operative time, which requires a good understanding of the anatomical relationship between the tumor and the conduction bundle both preoperatively and intraoperatively, and the white matter fiber bundle tracer imaging navigation technique will undoubtedly provide direct assistance in this regard. The evaluation of the anatomical validity of white matter fiber bundle tracer imaging, i.e., how to “confirm” its accuracy, is a critical issue, and the localization of white matter fiber bundles by electrophysiological monitoring and stimulation, and the comparison with white matter fiber bundle tracer imaging in the navigation system, should be an effective solution to the “confirmation” problem. The “confirmation” problem should be solved in an effective way. Intraoperative electrophysiological monitoring, including direct electrical stimulation of subcortical fibers, can help to correct the position of fiber structures in real time to compensate for brain drift, and electrophysiological monitoring is an effective method to verify white matter fiber bundle tracer imaging [8-11], therefore, combining direct fiber stimulation topography with fiber bundle tracer imaging navigation technology will greatly facilitate the research and application of both techniques. Kamada et al [11] combined the fiber bundle tracer imaging navigation technique and direct fiber bundle stimulation technique to surgically treat six patients involving the corticospinal tract (CST). A single excitation plane echo sequence MRI scan was performed preoperatively, DTI fiber bundle tracer imaging was performed, and the resulting fiber bundle tracer imaging was fused and reconstructed with conventional MRI images, and the fused image data were fed into the navigation system for intraoperative navigation. Intraoperatively, no inotropic agents were applied except for the induction phase of anesthesia. After craniotomy, somatosensory evoked potentials and motor evoked potentials are detected, and needle-shaped detection electrodes for motor evoked potentials are inserted under the skin of the palms and toes, and somatosensory evoked potentials and motor evoked potentials are continuously monitored throughout the operation. During tumor resection, direct fiber bundle electrical stimulation was performed when the navigation system suggested that the incision margin was close to the corticospinal tract, using five sequences of unidirectional square wave pulsed monopolar stimulation with a frequency of 1 Hz, a pulse duration of 0.2 ms, and a current intensity of 1-25 mA. The electrical fiber stimulation was applied to several points around the resection through strip electrodes to evoke motor evoked potentials in the palm and toes. In three of the six patients, direct fiber bundle stimulation evoked action potentials, and in one case, when the cut edge was less than 0.5 cm from the corticospinal bundle shown in the intraoperative navigation, the wave amplitude of motor evoked potentials decreased by 50%, and there was a brief postoperative paralysis of the deviated body. In the other two cases, the tumor margins were 1.0 cm and 0.5 cm from the navigated corticospinal tracts, respectively, and the action potentials evoked by direct fiber bundle stimulation were good, so these two cases achieved maximum tumor resection with functional preservation. The authors concluded that the results of intraoperative direct fiber bundle stimulation effectively validated the accuracy of magnetic resonance brain diffusion tensor white matter fiber bundle tracer imaging, and pointed out that the effective combination of direct fiber bundle stimulation technique and fiber bundle tracer imaging navigation technique will help to maximize tumor resection and better protect brain function, which has good prospects for development. In one case reported by Kamada [8], a glioma in the posterior part of the right temporal lobe, intraoperative fiber bundle tracer imaging navigation and visual evoked potentials were applied, and when the resection reached the visual radiation suggested by the navigation, the visual evoked potentials suddenly disappeared and the patient was left with complete left-sided hemianopia after surgery. The fiber bundle tracer imaging navigation technique is a new technique developed with the development of computer and magnetic resonance technology, and is currently the only method that can provide preoperative imaging information of the white matter fiber bundle. With the popularization of intraoperative magnetic resonance, intraoperative electrophysiological monitoring and continuous improvement of imaging technology, it will have a good prospect for development, which will help to maximize the resection of lesions and better protect brain function.