Introduction: Magnetic Resonance Imaging (MRI) offers unmatched potential for guiding interventional procedures [1]. However, in order for needle placement assistance mechanisms for these procedures to take hold, their setup and use must be straightforward and avoid lengthening the procedure. We propose a biplane laser guide that uses the intersection of calibrated laser planes to mark the intended needle trajectory. A comparison of this system to three other needle insertion techniques (including conventional freehand as a control) is performed. Methods: The proposed biplane laser guide consists of three main components: 1) a freestanding frame which arches over the patient couch and provides a track for translation of the lasers in the left-right direction, 2) a laser line generator that provides a laser plane parallel to the transverse imaging plane of the scanner, and 3) a second laser line generator attached to a manual rotation stage that generates a laser plane at a given angle off the vertical sagittal imaging plane. The intersection between the transverse and parasagittal laser planes defines the needle's trajectory. Bilateral needle insertions are often required; therefore, two such parasagittal lasers with angle guides are attached to the horizontal rail. Conceptually similar systems for use with CT imaging have been presented previously [2,3] and found to be superior to the unassisted freehand technique, but laser guidance has not been investigated in the context of MRI.
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