Enhanced vessel segmentation in ultrasound by registration with CT
Verbesserte Gefäßsegmentierung in Ultraschall durch Registrierung mit CT
In navigated liver surgery the surgeon depends on the combination of pre-operative CT scans, which are already acquired and used during the planning phase, and intra-operative ultrasound (U/S) scans, which reflect the current situation, especially the deformation the liver undergoes due to a different positioning of the patient. However, the high amount of noise and the low contrast in ultrasound scans makes the segmentation of the liver vascularity in ultrasound scans difficult. CT scans on the other hand offer a much better image quality and thereby a clear segmentations. Because of this, the two scans are often registered against each other to offer a basis of comparison for the surgeon. I take this approach even one step further and propose a segmentation technique that uses the information from the CT scan directly to improve the ultrasound segmentation. The new segmentation now serves two purposes: For one, the surgeon is supplied with additional information about the current situation of the liver and its deformation. The second purpose is that the newly found vessels offer an additional set of natural landmarks, which can be used in further registration steps.
Darmstadt, TU, Bachelor Thesis, 2013