• Haiying Liu, Walter A Hall, and Charles L Truwit.
• Center for MR-Guided Therapy, Department of Radiology, Medical School, University of Minnesota, Minneapolis, Minnesota 55455, USA. liuxx105@umn.edu
• Comput. Aided Surg. 2002 Jan 1;7(4):237-47.

AbstractThe objective of this study was to develop, demonstrate, and validate a remotely controlled operation scheme coupled with prospective magnetic resonance imaging (MRI)-based stereotaxy for in vivo neurosurgical applications. The novel concept of the prospective guidance scheme is to employ tomographical imaging feedback, such as MRI or CT, to facilitate prospectively the targeting process of a biopsy needle at near-real-time speed (1 image/s). Because the orientation of a biopsy needle pivoted at an entry point on the patient's skull has 2 degrees of freedom, the alignment of its trajectory to a target point can be guided by two-dimensional (2D) images whose plane is placed perpendicular to the desired trajectory. Using near-real-time 2D visual feedback during the adjustment of the alignment guide, the required trajectory alignment can be translated into a simple targeting task on a computer monitor employing a suitable graphic presentation. Also, both adjustments for the alignment and introduction of the biopsy needle were accomplished remotely with image-based feedback. The use of the method in actual MR-guided brain lesion biopsy procedures at 1.5 T showed an improved tissue yield due to the improved targeting accuracy even in the presence of brain shift. Furthermore, the postalignment trajectory can be validated immediately using near-real-time MRI scans in two orthogonal views before needle insertion. Because the final needle position is always visualized and confirmed, the consequent tissue sampling is performed with greater certainty, even in the case of a negative diagnosis. The actual targeting error was 1.53 +/- 0.17 mm from an intended target location, with the maximum distance error of 1.72 mm at a depth of 85 mm. This remotely controlled surgical approach with intraoperative MRI guidance is feasible at 1.5 T, and has allowed neurosurgeons to perform neurobiopsies comfortably and efficiently in a routine clinical MR scanner. This scheme provides a unique alternative stereotactic procedure that can take full advantage of the prospective guidance potential offered by various modern tomographic imaging systems.Copyright 2002 Wiley-Liss, Inc.

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