Evaluation of diffuse myocardial fibrosis in heart failure with cardiac magnetic resonance contrast-enhanced T1 mapping.
OBJECTIVE
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.
Iles
Leah
L
Alfred Hospital and Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
Pfluger
Heinz
H
Phrommintikul
Arintaya
A
Cherayath
Joshi
J
Aksit
Pelin
P
Gupta
Sandeep N
SN
Kaye
David M
DM
Taylor
Andrew J
AJ
D000328:Adult; D000704:Analysis of Variance; D018780:Body Surface Potential Mapping; D016022:Case-Control Studies; D005260:Female; D005355:Fibrosis / Q000175:diagnosis; D019786:Gadolinium DTPA; D006333:Heart Failure / Q000175:diagnosis*; D054144:Heart Failure, Diastolic / Q000175:diagnosis; D054143:Heart Failure, Systolic / Q000175:diagnosis; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology*; D011336:Probability; D011446:Prospective Studies; D012016:Reference Values; D012720:Severity of Illness Index
D019786:Gadolinium DTPA