Computer Assisted Medical Interventions

Computer-assisted Interventions

Computer-assisted Radiofrequency Ablation

Computer-assisted needle puncture: 3D overview of the scene after insertion (left) and projection view during insertion (right).

Traditional open surgical procedures are increasingly being replaced by minimally invasive techniques for cancer diagnosis and therapy within the scope of clinical practice. These procedures typically require insertion of a surgical instrument into the organ of interest with a high degree of accuracy. In general, the success of a treatment or of a diagnosis is highly dependent upon the accuracy of instrument insertion and thus, depends crucially on the skills and experience of the physician.

Within the Research Training Troup 1126: Intelligent Surgery new concepts for computer-assisted soft tissue interventions have been developed, implemented and evaluated in close collaboration with clinical partners from the University Hospital Heidelberg. Our main contributions during the first phase of the project include (1) a real-time capable motion compensation method for percutaneous abdominal interventions based on fiducial needles [MaieL08], (2) a guidance method to allow for fast and precise insertion of a needle-shaped instrument along a predetermined trajectory [SeitA07] (cf. Fig. 1b), and (3) a planning system that allows for choosing safe needle trajectories to the target [SeitA11] (cf. Fig. 2).

As the liver is one of the most common sites for metastatic disease and, at the same time, one of the organs most affected by respiratory motion, a prototype system for guided liver punctures was developed along the lines of theproposed concepts. According to an in-vivo accuracy assessment study, the approach is highly accurate compared to state-of-the-art work, yielding an overall needle insertion error of about 3 mm [MaieL08]. Furthermore, the proposed method outperforms the conventional CT-guided needle insertion method with respect to accuracy and radiation exposure to the patient [Müll10]. Integration of a medical robot further reduced the user error by more than 50% [MaieL09]. Finally, the planning method is able to detect unsafe insertion trajectories and propose safe ones [SeitA11].

Recently, the established concepts have been extended to allow for workflow-optimized guidance.

Computer-assisted path planning. First, possible insertion zones on the skin are calculated, which exclude those needle trajectories to the target violating at least one of the specified conditions (hard constraints, see 3D view). For example, the needle must not pass through any critical structures and the selected path must be shorter than the needle which is to be inserted. In a second step, the quality of the remaining possible access pathways is evaluated by means of soft constraints which, for example, require a large distance to critical structures and as short a trajectory as possible.

Selected publications

[MaieL09] Maier-Hein L, Walsh CJ, Seitel A, Hanumara NC, Shepard JA, Franz AM, Pianka F, Müller SA, Schmied B, Slocum AH, Gupta R, Meinzer HP. Human vs. robot operator error in a needle-based navigation system for percutaneous liver interventions. In Wong KH, Miga MI (ed.). Proceedings of SPIE Medical Imaging 2009: Visualization, Image-Guided Procedures, and Modeling, 2009, 7261, 72610X (2009).

[MaieL08] Maier-Hein L, Tekbas A, Seitel A, Müller SA, Satzl S, Schawo S, Radeleff B, Tetzlaff R, Franz AM, Müller-Stich BP, Wolf I, Kauczor HU, Schmied BM, Meinzer HP. In-vivo accuracy assessment of a needle-based navigation system for CT-guided radiofrequency ablation of the liver. Med Phys 35(12): 5385-5396, 2008.

[Müll10] Müller SA, Maier-Hein L, Tekbas A, Seitel A, Ramsauer S, Radeleff B, Franz AM, Tetzlaff R, Mehrabi A, Wolf I,Kauczor HU, Meinzer HP, Schmied BM.Navigated Liver Biopsy Using a Novel Soft Tissue Navigation System versus CT-guided Liver Biopsy in a Porcine Model: A Prospective Randomized Trial.AcadRadiol17(10): 1282-1287, 2010.
[SeitA07] Seitel A, Maier-Hein L, Schawo S, Radeleff BA, Mueller SA, Pianka F, Schmied BM, Wolf I, Meinzer HP. In-vitro evaluation of different visualization approaches for computer assisted targeting in soft tissue. International Journal of CARS 2 (Suppl 1), pp. 188-190, 2007.

[SeitA11] Seitel A, Engel M, Sommer CM, Radeleff BA, Essert-Villard C, Baegert C, Fangerau M, Fritzsche KH, Yung K, Meinzer HP, Maier-Hein L. Computer-assisted trajectory planning for percutaneous needle insertions. MedPhys 38 (6): 3246-59, 2011.

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