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 gender-matched 
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 significantly 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<0.05). The strongest associations with T1 
values were for aortic valve area (r=-0.40, p=0.001) and left ventricular mass 
index (LVMI) (r=0.36, p=0.008), and these were the only independent predictors 
on multivariate analysis.
CONCLUSIONS: Non-contrast T1 values are increased in patients with severe AS and 
further increase in symptomatic compared with asymptomatic patients. T1 values 
lengthened with greater LVMI and correlated with the degree of biopsy-quantified 
fibrosis. This may provide a useful clinical assessment of diffuse myocardial 
fibrosis in the future.