Human non-contrast T1 values and correlation with histology in diffuse fibrosis

Background: Aortic stenosis (AS) leads to diffuse fibrosis in the myocardium, which is linked to adverse outcome. Myocardial T1 values change with tissue composition. Objective: To test the hypothesis that our recently developed non-contrast cardiac magnetic resonance (CMR) T1 mapping sequence could identify myocardial fibrosis without contrast agent. Design, setting and patients: A prospective CMR non-contrast T1 mapping study of 109 patients with moderate and severe AS and 33 age- and gendermatched controls. Methods: CMR at 1.5 T, including non-contrast T1 mapping using a shortened modified Look-Locker inversion recovery sequence, was carried out. Biopsy samples for histological assessment of collagen volume fraction (CVF%) were obtained in 19 patients undergoing aortic valve replacement. Results There was a significant correlation between T1 values and CVF% (r=0.65, p=0.002). Mean T1 values were signi ficantly longer in all groups with severe AS (972±33 ms in severe asymptomatic, 1014 ±38 ms in severe symptomatic) than in normal controls (944±16 ms) ( p