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Autonomous navigation assistant for MRI guided interventions

: Friebe, M.; Sachtler, D.; Hellwig, S.; Schlüter, M.; Sakas, Georgios; Jorczyck, U.

Kronreif, G. ; Society for Medical Innovation and Technology -SMIT-, Weimar:
SMIT 2008, 20th International Conference of the Society for Medical Innovation and Technology. Electronic Proceedings. DVD-ROM : 28 - 30 August 2008, Vienna, Austria
Seibersdorf: PROFACTOR Research and Solutions, 2008
ISBN: 3-902087-25-0
4 S.
Society for Medical Innovation and Technology (SMIT International Conference) <20, 2008, Vienna>
Fraunhofer IGD ()
magnetic resonance imaging (MRI); Preoperative planning; surgical planning

Interventions, like biopsies, tumor therapy, injection of drugs, placements of intravascular implants (stents, coils, etc.) and many more are performed image guided. MRI would be the preferred guidance device due to the fact that it provides the best soft tissue contrast and comes with no or little negative side effects for the human body. Several known problems have to be overcome while working in or around a MRI system, mainly related to the strong magnetic and electric fields, which require the use of special materials and special shielding.
Interventions are also limited due to the relatively small openings of the horizontal magnet systems (bore diameter of 60 cm to 70 cm). Open scanners facilitate the access to the patient much better, but they also use lower magnetic field strength and therefore do not provide equally good image quality. Interventions are therefore usually performed outside of the magnet bore. This requires moving the patient in and out of the magnet as the actual position of a medical instrument has to be frequently updated through newly acquired images. Workflow and quality of intervention - in the case of a needle therapy for example - could be significantly improved, if the physician would know where to penetrate skin, in which angle to hold the instrument and what the distance from skin to target (organ, tumor, etc.) is. Devices inside the MRI bore could mark the penetration point including the required angle with a laser on the patient's skin after the intervention was planned by a physician on the previously obtained MR images. Also, a mechanical apparatus could be aligned by such a device, through which the instrument can be inserted into the body.
Several of such systems have been proposed, but all are complicated, very expensive, and further limit the available space inside the bore. The goal was therefore to develop an innovative and inexpensive navigation assistant, to be placed inside the bore of the MRI system (reduced size) - but with the option to also use it outside the magnet - which is able to identify (with e.g. a laser diode) the desired entry position (point of skin penetration and angle of penetration) for the intervention/therapy on the patients body.