Myocardial extracellular volume fraction quantification based on T1 mapping at 3 T: quality optimization by contour-based registration and segmental analysis.

ABSTRACT

BACKGROUND: Myocardial extracellular volume fraction (ECV) assessment can be affected by various technical and subject-related factors. PURPOSE: To evaluate the role of contour-based registration in quantification of ECV and investigate normal segment-based myocardial ECV values at 3T. MATERIAL AND METHODS: Pre- and post-contrast T1 mapping images of the left ventricular basal, mid-cavity, and apical slices were obtained in 26 healthy volunteers. ECV maps were generated using motion correction with and without contour-based registration. The image quality of all ECV maps was evaluated by a 4-point scale. Slices were dichotomized according to the occurrence of misregistration in the source data. Contour-registered ECVs and standard ECVs were compared within each subgroup using analysis of variance for repeated measurements and generalized linear mixed models. RESULTS: In all three slices, higher quality of ECV maps were found using contour-registered method than using standard method. Standard ECVs were statistically different from contour-registered ECVs in global (26.8% ± 2.8% vs. 25.8% ± 2.4%; P = 0.001), mid-cavity (25.4% ± 3.1% vs. 24.3% ± 2.5%; P = 0.016), and apical slices (28.7% ± 4.1% vs. 27.2% ± 3.4%; P = 0.010). In the misregistration subgroups, contour-registered ECVs were lower with smaller SDs (basal 25.2% ± 1.8% vs. 26.7% ± 2.6%; P = 0.038; mid-cavity 24.4% ± 2.3% vs. 26.8% ± 3.1%; P = 0.012; apical 27.5% ± 3.6% vs. 29.7% ± 4.5%; P = 0.016). Apical (27.2% ± 3.4%) and basal-septal ECVs (25.6% ± 2.6%) were statistically higher than mid-cavity ECV (24.3% ± 2.5%; both P < 0.001). CONCLUSION: Contour-based registration can optimize image quality and improve the precision of ECV quantification in cases demonstrating ventricular misregistration among source images.