An Adaptive MR-Compatible Lens and Objective

This work presents an MR-compatible adaptive liquid lens, designed to form part of an in-bore optical imaging system. The lens is integrated into a wide-angle objective, which is suitable for use with a camera mounted above the head coil to monitor subject head motion. Compatibility tests indicate that focusing of the lens is unaffected by the static, gradient, or radio frequency (RF) fields of the scanner. Field mapping shows that no B-0 field distortions are visible with the system mounted 55 mm above a water-filled phantom. The total increase in RF noise observed on a 1.5-T system when using the lens and lighting setup is less than 2%, and this is mostly attributable to the lighting. This work was originally motivated by head tracking for prospective motion correction; however, the lens may have other applications whenever high-quality optical images are required in the MR environment and motion of the object makes a fixed lens unsuitable. (C) 2011 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 39B: 141-148, 2011