TY - JOUR T1 - MRI investigation of the relationship between the motion of external markers on the body surface and motion of the heart within the chest JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 587 LP - 587 VL - 50 IS - supplement 2 AU - Michael King AU - Joyoni Dey AU - Joseph McNamara AU - Karen Johnson AU - Joyeeta Mitra AU - Hendrik Pretorius AU - Yanping Sun Y1 - 2009/05/01 UR - http://jnm.snmjournals.org/content/50/supplement_2/587.abstract N2 - 587 Objectives We have developed a visual-tracking-system (VTS) which assumes a rigid-body-motion (RBM) model to correct in iterative reconstruction the motion of the heart based on stereo-imaging measured motions of multiple markers attached to bands wrapped about patients undergoing SPECT imaging. The objective of this study was to use MRI of volunteers to evaluate the RBM model. Methods We investigated the RBM assumption by imaging volunteers simultaneously with the VTS to track markers and MRI to determine the location of the heart within the chest. Body-motion was isolated from respiratory motion by having the volunteer hold their breath during the acquisition of a sequence of 2 sets of MRI images, one pre-motion and the other post-motion. The motion of the heart within the slices was estimated by semi-automatic 3D segmentation of the heart region in the second set of slices and subsequent registration of this region to the first set of slices. We investigated a variety of motions such as translations, rotations, twisting, and arm movement. Results With body translations the maximum difference in any translation estimate was similar to that of the baseline of having the volunteers not intentionally move. With more complex motions like twists and bends, the VTS would considerably decreased the magnitude of the misalignment caused by motion but not to the same extent as for simple translations. Conclusions The RBM model can be used to correct the motion of the heart due to body translations. For more complex motions a RBM model based estimate decreases the error, but refinement of this estimate would lead to a further improvement in correction accuracy. Research Support NIH R01 EB001457, and Philips Medical Systems. ER -