In the last 10 years, diffusion in biological tissues is increasingly studied by using magnetic resonance imaging techniques. More recently, diffusion tensor imaging is attracting the biomedical researchers for its application in depiction of fiber tracts based on diffusion anisotropy. For example, information of white matter tracts depicted by diffusion tensor analysis helps neuro-surgical navigation as well as vascular information. In this review paper, determination process of diffusion tensor in multi-channel magnetic resonance data, and several visualization techniques, such as tractography, are described briefly, and then several examples are shown using clinical data. The basic concepts of diffusion tensor analysis, and advantages and disadvantages of the visualization techniques are also discussed.
In most of existing surgical training systems, task completion time and error ratio are common metrics for surgical skill evaluation. To avoid unnecessary and injurious force to the tissue, surgeons must know for themselves how much force they give in handling surgical tools. Our goal is to develop an endoscopic sinus surgery (ESS) training system that quantitatively evaluates the trainee's surgical skills. In this paper, we present an ESS training system with force sensors for surgical skill evaluation. Our experiment revealed that the integral of the force data can also be one of the useful metrics for surgical skill evaluation.
In this paper, an endoscope manipulator for transnasal neurosurgery, which is open MR-compatible, and MRcompatibility tests of the first prototype are reported. This manipulator holds and manipulates an endoscope inside MR gantry, to provide the surgeon (s) with real images of the section corresponding to MR image. To avoid mutual malfunction, the prototype was mainly embeded with non-magnetic materials and actuators, like titanium, MC-nylon, ceramic bearing, ultrasonic motors and so on. However, the MR-incompatible materials were allowed to be used according to the distance from imaging area, because they are advantageous in terms of stiffness and cost. Although magnetic materials were used, MR-compatibility tests resulted that the prototype worked regularly, and that the effects on MRI were negligible as long as actuators were inactive while MR-scanning.
In order to complement the limitation of real-time MR images for MR-guided surgery, navigation software was customized to display the real-time image and 2 re-sliced images (same and perpendicular planes to the real-time image) from high resolution 3D volume data registered beforehand. Re-sliced images showed higher image quality, faster response, and easier recognition of the target than the real-time MR image. Images with different contrast, such as T2-weighted images, Gd-enhanced images and also CT images could be used for navigation. The integration of the customized software was quite helpful for easier and more accurate image navigation in MR-guided surgery.