CASS Tumor Volume Resection System
The advanced imaging and graphics capabilities of CASS can be used to plan and simulate stereotactic microsurgical 3-D Tumor Volume Resection. Commonly available "microcathers" or "micropatties" are placed as visual markers to define and locate tumor margins. These surgical markers are then projected into 3-D MR/CT stereotactic frame space to aid in microsurgical resection.
In the 3-D Tumor Volume Resection (CASS-TVR) software module, routines are available for the positioning of multiple catheters with various trajectories to define a tumor's margin with the aid of 3-dimensional simulation and multimodality imaging. MR, CT, angiography, and PET/SPECT imaging can be combined/fused in various ways in 3-D simulation for additional imaging information. After performing a craniotomy, the dura is reflected and catheters are positioned at selected sites and depths marked by the use of clips placed on each catheter. Using small cannulas, such catheters are stereotactically placed so that they skirt along the tumor's margin and end at a depth which represents the most distal extent of the lesion along a given catheter's trajectory. Catheters so positioned serve as reliable tumor boundary markers, and have the added advantage of shifting with the tumor margins as the surrounding brain shifts or moves during the resection. The markers, therefore, act as "tumor margin fiducials." The surgical microscope can be freely used during these volume resections. Additionally, since most brain tumors are amoeboidal and not cylindrical or ellipsoidal in shape, the microscope can also be angularly adjusted to view portions of the tumor which can be seen through the crainiotomy approach, but which are not on a direct viewing angle parallel to that approach. That is, the microscope can be angled backward or to one side or the other to reach distant margins of the lesion.
The computer rapidly determines each catheter's target (tip position) and trajectory (entry point), and will simulate 1 cm incremental marks along each catheter's trajectory. The entire surgical procedure can be planned and simulated in a "what-if" fashion after the imaging studies have been done, but prior to beginning the actual procedure. Once a primary trajectory has been chosen for an approach to the tumor, CASS will automatically present reformatted images perpendicular to that trajectory to simulate the surgeon's view. These reformatted slices are incrementally adjusted in the 3-D view as the dissection proceeds, and the relationship of the catheters to a volume rendition of the tumor in stereotactic space can be noted. Such reformatted images can also be combined with standard sagittal, frontal, and horizontal images, as well as surface modeling and CASS brain maps.
- Automatic Frame Calibration (and Skull Contouring)
- 3-D Imaging and Graphics
- User-Defined Multiplanar Reformatting
- Tumor Volume Rendition in Wire Frame, Solid, or Transparency format
- Microcatheter or Micropatty Positioning via CASS Surgeon's-Eye View
- 3-D Visual Optimization
Integration with CASS Whole Brain Mapping
The adjustment and variation of a stereotactic probe's depth and trajectory during the course of a craniotomy can aid in locating the margins of a tumor during volume resection. We have found this method to be very reliable and cost effective in the sense that no additional expensive equipment, other than the equipment for computer imaging was necessary.