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.


METHODS
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.
Department of Cardiovascular Medicine, University of Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Level 0, Headley Way, Oxford OX3 9DU, UK.
Sacha
S
Bull
Steven K
SK
White
Stefan K
SK
Piechnik
Andrew S
AS
Flett
Vanessa M
VM
Ferreira
Margaret
M
Loudon
Jane M
JM
Francis
Theodoros D
TD
Karamitsos
Bernard D
BD
Prendergast
Matthew D
MD
Robson
Stefan
S
Neubauer
James C
JC
Moon
Saul G
SG
Myerson
D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000737:chemistry / Q000473:pathology*; D001024:Aortic Valve Stenosis / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology*; D058070:Asymptomatic Diseases; D015415:Biomarkers / Q000032:analysis; D001706:Biopsy; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003094:Collagen / Q000032:analysis; D004739:England; D005260:Female; D005355:Fibrosis; D006352:Heart Ventricles / Q000737:chemistry / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009206:Myocardium / Q000737:chemistry / Q000473:pathology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012720:Severity of Illness Index
D015415:Biomarkers; D003094:Collagen