OBJECTIVES: The purpose of this study was to investigate a noninvasive method 
for quantifying diffuse myocardial fibrosis with cardiac magnetic resonance 
imaging (CMRI).
BACKGROUND: Diffuse myocardial fibrosis is a fundamental process in pathologic 
remodeling in cardiomyopathy and is postulated to cause increased cardiac 
stiffness and poor clinical outcomes. Although regional fibrosis is easily 
imaged with cardiac magnetic resonance, there is currently no noninvasive method 
for quantifying diffuse myocardial fibrosis.
METHODS: We performed CMRI on 45 subjects (25 patients with heart failure, 20 
control patients), on a clinical 1.5-T CMRI scanner. A prototype T(1) mapping 
sequence was used to calculate the post-contrast myocardial T(1) time as an 
index of diffuse fibrosis; regional fibrosis was identified by delayed contrast 
enhancement. Regional and global systolic function was assessed by cine CMRI in 
standard short- and long-axis planes, with echocardiography used to evaluate 
diastology. An additional 9 subjects underwent CMRI and endomyocardial biopsy 
for histologic correlation.
RESULTS: Post-contrast myocardial T(1) times correlated histologically with 
fibrosis (R = -0.7, p = 0.03) and were shorter in heart failure subjects than 
controls (383 +/- 17 ms vs. 564 +/- 23 ms, p < 0.0001). The T(1) time of heart 
failure myocardium was shorter than that in controls even when excluding areas 
of regional fibrosis (429 +/- 22 ms vs. 564 +/- 23 ms, p < 0.0001). The 
post-contrast myocardial T(1) time shortened as diastolic function worsened (562 
+/- 24 ms in normal diastolic function vs. 423 +/- 33 ms in impaired diastolic 
function vs. 368 +/- 20 ms in restrictive function, p < 0.001).
CONCLUSIONS: Contrast-enhanced CMRI T(1) mapping identifies changes in 
myocardial T(1) times in heart failure, which appear to reflect diffuse 
fibrosis.