Felix V. Guettler, Presenter: Nothing to Disclose

Jens Rump, Abstract Co-Author: Nothing to Disclose

Peter Krauß, Abstract Co-Author: Nothing to Disclose

Christian Seebauer, Abstract Co-Author: Nothing to Disclose

Bernd K. Hamm MD, Abstract Co-Author: Research Consultant, Bayer AG Research Consultant, Toshiba Corporation Stockholder, Siemens AG Stockholder, General Electric Company Stockholder, Biomed Research grant, Toshiba Corporation Research grant, Koninklijke Philips Electronics NV Research grant, Siemens AG Research grant, General Electric Company Research grant, Elbit Medical Imaging Ltd Research grant, Bayer AG Research grant, Guerbet AG Research grant, Bracco Group Research grant, B. Braun Research grant, Knauth Research grant, Boston Group Equipment support, Elbit Medical Imaging Ltd Investigator, Copenhagen Malmo Contrast AB, Lund, Sweden

Ulf Karl Martin Teichgraeber MD, Abstract Co-Author: Nothing to Disclose

Optical tracking systems measure the 3D relative position of at least three infrared-reflective markers affixed to a carrier device. The aim of this study is the dynamic control of the MRI, based on the position of surgical instruments.

The experimental setup includes an MRI (Philips Panorama HFO), an optical tracking system (NDI Polaris) and a computer connected to both devices. The computer continuously receives the spatial information of tracked objects (target) from the optical tracking system. Position and rotation given by the optical tracking system are synchronized to MR scanner's coordinate system. The MRI receives the information and readjusts the image plane for the next acquisition. The influence of the optical tracking system on the MR image quality and the artifact size was measured. To quantify the enhancement of the surgical workflow 10 surgeons did 2 series of 5 punctures on a phantom in the MRI. In the first series the surgeons controlled the MR image plane on their own with the support of the tracking system. At the second trial the puncture was done by the aid of a medical technical assistant.

The MR image plane was directly controlled by handheld target at one image per three seconds. No significant loss of SNR was found with the use of the optical tracking system inside the MR environment. The maximum artifact size of the target handle was 111 mm and only showed minimal difference compared to the real size of 87 mm. The ASTM test to assess magnetic attraction revealed an object deviation of less than 1° at 2.4 T/m at 35 g and is therefore below the maximum permitted deviation for MR-compatibility. Among questionnaire items a significant positive correlation was found between the use of the tracking system compared to the common practice via an MTA and hand signal communication.

We hereby conclude using optical tracking for the dynamic control of the image plane of MR guided interventions is safe and feasible and may advance the surgery workflow by simplifying navigation and orientation.

Dynamic control of the MRI by the surgeon is helpful for MR-guided interventions like biopsies or punctures. Also this system could be adjuvant for MR- guided orthopaedic and spinal interventions.

Guettler, F, Rump, J, Krauß, P, Seebauer, C, Hamm, B, Teichgraeber, U, Dynamic Control of Real-Time MR imaging with an Optical Tracking System.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9014238.html