hp-GRAPPA for Delayed Enhanced Imaging of the Left Atrium

Introduction: Radio frequency (RF) ablation of the left atrium (LA) and pulmonary vein (PV) ostia has become a clinically acceptable therapy for atrial fibrillation (AF) [1,2]. Recently, a delayed enhancement MRI (DE-MRI) technique has been proposed to visualize and assess the extent of post-ablation scar [3]. This technique visualizes scar in the posterior wall of the LA and the PV ostia where the RF ablation has been performed. This can be useful for predicting outcome of procedure [4] and to detect gaps in the ablation pattern for repeated ablation procedures. To quantify scar and predict procedure outcome, one needs to be able to visualize wall of the LA very accurately. It should be noted however, that the wall of the LA is very thin (2-5 mm) and hence, the high frequency components of k-space are critical for the best reconstruction of these images. Recently, in [5], a reconstruction scheme was proposed for parallel imaging where high frequency components of k-space are better preserved and reconstructed with the use of a high pass filter. In this work, we applied this technique, high-pass GRAPPA (hp-GRAPPA), to get better DE image quality at higher acceleration factors.