Real-Time Adaptive suppression of MR gradient Artifacts on Electorcardiograms using a new 3D Hall Probe

International audienceDue to heart motion, cardiac MRI is made difficult and image acquisitions have to be synchronized with heart activity to suppress cardiac motion artifacts. Electrocardiogram (ECG) is the most accurate tool for this purpose, and Triggering consists in synchronizing MR sequences on the R-waves. The complex MR environment worsens ECG acquisition conditions because of the static magnetic field (Hall Effect), Radio Frequency (RF) and fast switching magnetic field gradients. Many hardware developments have been achieved so as to limit these undesirable effects [1], but gradient artifacts are still a problem and signal processing is required. Two ways of research have been followed; (a) first way consists in building a MR specific QRS detector [2], which is based on the vectocardiogram (VCG) the 3D representation of heart activity. This method does unfortunately not provide a clear ECG and is unable to process patient with low VCG amplitude. (b) Secondly a real-time gradient artifact suppression method has been designed. This method is based on adaptive signal processing [3] and achieves real-time accurate denoising which enables triggering. This method requires gradient signals information, which is a major drawback as the connection to the MR system is rarely available. In this paper a new real-time gradient artifact correction, which does not require any connection to the MR system, is presented. The magnetic field pulse signals will be provided by a new specifically MR designed 3D Hall probe, integrated on a low cost 0.35\μm CMOS technology [4, 5]