Visualization of active devices and automatic slice repositioning (“SnapTo”) for MRI‐guided interventions

The accurate visualization of interventional devices is crucial for the safety and effectiveness of MRI‐guided interventional procedures. In this paper, we introduce an improvement to the visualization of active devices. The key component is a fast, robust method (“CurveFind”) that reconstructs the three‐dimensional trajectory of the device from projection images in a fraction of a second. CurveFind is an iterative prediction‐correction algorithm that acts on a product of orthogonal projection images. By varying step size and search direction, it is robust to signal inhomogeneities. At the touch of a key, the imaged slice is repositioned to contain the relevant section of the device (“SnapTo”), the curve of the device is plotted in a three‐dimensional display, and the point on a target slice, which the device will intersect, is displayed. These features have been incorporated into a real‐time MRI system. Experiments in vitro and in vivo (in a pig) have produced successful results using a variety of single‐ and multichannel devices designed to produce both spatially continuous and discrete signals. CurveFind is typically able to reconstruct the device curve, with an average error of approximately 2 mm, even in the case of complex geometries. Magn Reson Med 63:1070–1079, 2010. © 2010 Wiley‐Liss, Inc.