infoRAD exhibit shows 3D visualization technique for interventional planning

An interactive visualization technique for interventional planning with a focus on liver surgery was presented in an infoRAD demonstration at the RSNA meeting Sunday morning.

The system generates 3D visualization of relevant anatomic and pathologic structures of the liver that can be freely manipulated. Presentation parameters, such as colors and transparency values, can be flexibly assigned to specific objects such as lesions, vessels, and vascular territories.

By carefully selecting default values, the user can minimize interaction effort. All objects are simultaneously overlaid to a 2D view that presents the original radiological data. Three-D measurement tools for the assessment of distances and angles are available for quantitative analysis.

"We have developed an application for preoperative planning in liver surgery that does all parts of image analysis required for preoperative planning," said Dr. Holger Bourquain of the Centrum feur Medizinische Diagnosesysteme und Visualisierung in Bremen, Germany.

Bourquain's system deals with segmentation of the liver, segmentation of tumors if they are present, segmentation of vessel structures, and hierarchical analysis of vessel structures. This means the computer automatically detects where the roots of these vessel systems are and identifies which branch is connected to which other branch.

"If you select one branch, for example, all its sub-branches are selected automatically so you can easily edit the tree," Bourquain said.

In this case, edit means you label these branches and say, for example, this is the branch supplying segment seven of the liver. This segment can be represented by a certain color, or a numeral ë7' can easily be written on it.

"Based on segmentation of the liver and models of the vessel system, we can calculate the vessel territories supplied by each of these branches individually. With this help, you can identify exactly where in segment a tumor is located," Bourquain said.

The software, which was developed for research purposes in Germany, is used for planning of oncologic resections and for planning liver transplantations.

"For transplantation, you can quite easily estimate the volumes of the right and left lobe of the liver. You can, of course, manually define a resection line, including or excluding the middle hepatic vein from the graph, which is really the only important structure in this type of operation or therapy planning," he said.