Chair for Computer Aided Medical Procedures & Augmented Reality
Lehrstuhl für Informatikanwendungen in der Medizin & Augmented Reality

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Bachelor thesis

Advanced Intra-operative Visualization In Neurosurgery

Student: Andre Aichert
Supervision by: Oliver Kutter

Due date:


In the course of this thesis a high quality visualization system for neuro surgery has been created. It's focus is intra operative use, offering techniques to combine CT and/or MR visualization with both opaque geometry (such as tracked instruments) and ultrasound. "Peeling" of occluding iso layers (such as the skull bone) is performed to visualize inside structures. Focus and context rendering using a spherical focus region makes sure that geometric and positional clues from bony structres are not lost during brain visualization.Due to the extensive use of advanced GPU programming the visualization fulfills real time requirements.
Find below a chart of the pileline implemented and some screenshots.


Data Flow
Notice the ray casting for volume rendering is devided into several steps in the pipeline.

Tools and US plane inside skull for demonstration
Here, a flat texture and dummy geometry have been used to demonstrate the functionality.

Screenshot with strange TF
This surface is the color coded ray start for the second ray cast pass. The first pass must stop at the US/Object surface to allow correct occlusions.

Screenshot with strange TF
These high quality volume renderings run easily at real time framerates for a decent desktop computer with a moderate graphics card.

Peeling to visualize sinus
In this image peeling is applied to both skin and bone to visualize the frontal sinus.

Peeling to visualize sinus
The entire system has been implemented from scratch within four months. Here is a screenshot from the general volume renderer.

-- AndreAichert - 11 Jun 2009

Title: Advanced Intra-operative Visualization In Neurosurgery
Abstract: Abstract With the advance of imaging facilities and their broad availability in medicine it has become essential to combine data from multiple image modalities such as Computed Tomography (CT) or Magnet Resonance Imaging (MRI) data and recently ultrasound (US) into one view. Images are important both in pre-operative planning in intra-operative guidance and in post-operative evaluation and verification of the success. The most time-sensitive task is intra-operative guidance, as it does not allow for much input of the physician. Within the workflow of an intervention the right data has to be available at the right time. This work summarizes the possibilities offered to key hole surgery of the brain by today's advanced visualization techniques. With this application in mind a simple focus and context real-time volume renderer is implemented that tries to tackle some of the problems inherent to intra-operative use and discusses it's design. It has the aim of integrating CT and/or MRI with US in one focus and context view of the volume. To visualize the brain special methods to remove the cranial bone occluding the brain have to be used. A major issue is the integration of ultrasound into this multi-pass focus and context visualization. A complete pipeline is designed that can handle all of the above in a real time approach. As a proof-of-concept a straight forward volume renderer is implemented that supports the techniques presented in the thesis.
Student: André Aichert
Supervisor: Oliver Kutter
Type: DA/MA/BA
Area: Registration / Visualization, Medical Imaging
Status: finished
Finish: 2008/10/15
Thesis (optional):  

Edit | Attach | Refresh | Diffs | More | Revision r1.5 - 07 Dec 2011 - 13:51 - EtibarTaghiyev