Quantification of Left Atrium Fibrosis From Late Gadolinium Enhanced MRI in Atrial Fibrillation

Alice Andalò1, Claudio Fabbri1, Maddalena Valinoti1, Alessandro Masci1, Cristiana Corsi2
1DEI, University of Bologna, 2DEI- University of Bologna


Abstract

Introduction. The DECAAF study reported that extent of fibrosis in the left atrium (LA) in atrial fibrillation (AF) patients may predict recurrences after the ablation procedure. Therefore this information may help the electrophysiologist in patient’s selection for the ablation procedure. Late gadolinium enhanced magnetic resonance imaging (LGE-MRI) is a recent technique used for LA fibrosis distribution assessment in the LA wall. Unfortunately, LGE-MRI analysis does not rely on a standardized image processing protocol. The aim of the study was to compare the results obtained applying different methods to quantify fibrosis in the LA in the 3D domain. Methods. LGE-MRI from 60 AF patients acquired at the CARMA Center (University of Utah) in which manual tracing of LA wall by expert radiologist was available, were analysed applying five different approaches for fibrosis segmentation: an histogram-based (H-6SD), the image intensity ratio (IIR), the blood pool normalization (BP), the Chan-Vese (CV) and the graph-cut (GC). For each technique we quantified the percentage of fibrosis with respect to the entire LA wall mass. Results. Results showed these five approaches can be divided in two groups; the group composed by the H-6SD, CV and GC is characterized by similar results (mean coefficient of variation=0.3), while the results obtained applying BP and IIR strongly depend on the quality of the acquisition (mean coefficient of variation=0. 62). Utah stage classification resulted in a wide disagreement (22/60 patients, 37%) among BP and IIR. The two approaches which best matched the Utah classification were the CV and GC (49/60 patients, 82%) Conclusions. This study confirmed the evaluation of the quantification method appears critical and further research is needed to define a satisfactory standard for the segmentation of atrial fibrosis. A standardized image acquisition protocol would improve the performance of methods based on blood pool reference values.