Assessment of Diffuse Myocardial Fibrosis in Rats Using Small-Animal Look-Locker Inversion Recovery T1 Mapping
Open Access
- 1 November 2011
- journal article
- research article
- Published by Ovid Technologies (Wolters Kluwer Health) in Circulation: Cardiovascular Imaging
- Vol. 4 (6), 636-640
- https://doi.org/10.1161/circimaging.111.966796
Abstract
The concentration of gadopentetate dimeglumine in myocardium and blood can be assessed from T1 measurements and can be used to calculate the extracellular volume (ECV) of the myocardium. We hypothesized that diffuse myocardial fibrosis in a small-animal model could be quantitatively assessed by measuring myocardial ECV using small-animal Look-Locker inversion recovery T1 mapping. Sprague-Dawley rats (n=10) were subjected to continuous angiotensin-2 (AT2) infusion for 2 weeks via a subcutaneously implanted minipump system. Magnetic resonance imaging (MRI) was performed both before and after AT2 infusion. The MRI protocol included multislice cine imaging and before-and-after contrast small-animal Look-Locker inversion recovery T1 mapping and late gadolinium enhancement imaging. Myocardial ECV was calculated from hematocrit and T1 values of blood and myocardium. During the course of AT2 infusion, the mean±SD systolic blood pressure increased from 122±10.9 to 152±27.5 mm Hg ( P =0.003). Normalized heart weight was significantly higher in AT2-treated animals than in control littermates ( P =0.033). Cine MRI documented concentric left ventricular hypertrophy. Postcontrast myocardial T1 times were shortened after treatment (median [interquartile range], 712 [63] versus 820 [131] ms; P =0.002). Myocardial ECV increased from 17.2% (4.3%) before to 23.0% (6.2%) after AT2 treatment ( P =0.031), which was accompanied by perivascular fibrosis and microscarring on myocardial histological analysis. There was a moderate level of correlation between ECV and collagen volume fraction, as assessed by histological analysis ( r =0.69, P =0.013). In a small-animal model of left ventricular hypertrophy, contrast-enhanced T1 mapping can be used to detect diffuse myocardial fibrosis by quantification of myocardial ECV.Keywords
This publication has 19 references indexed in Scilit:
- Assessment of Myocardial Fibrosis With Cardiovascular Magnetic ResonanceJournal of the American College of Cardiology, 2011
- The Effect of Cardiac Fibrosis on Left Ventricular Remodeling, Diastolic Function, and N‐Terminal Pro‐B‐Type Natriuretic Peptide Levels in Patients with Nonischemic Dilated CardiomyopathyEchocardiography, 2010
- Cellular and molecular pathways to myocardial necrosis and replacement fibrosisHeart Failure Reviews, 2010
- Evaluation of Diffuse Myocardial Fibrosis in Heart Failure With Cardiac Magnetic Resonance Contrast-Enhanced T1 MappingJournal of the American College of Cardiology, 2008
- The Future of Cardiovascular Imaging in the Diagnosis and Management of Heart Failure, Part 1Circulation: Cardiovascular Imaging, 2008
- Late Gadolinium Enhancement by Cardiovascular Magnetic Resonance Heralds an Adverse Prognosis in Nonischemic CardiomyopathyJournal of the American College of Cardiology, 2008
- Comparison of Simultaneous Measurements of Blood Pressure by Tail-Cuff and Carotid Arterial Methods in Conscious Spontaneously Hypertensive and Wistar-Kyoto RatsClinical and Experimental Hypertension, 2006
- Enhanced expression of fibrillin-1, a constituent of the myocardial extracellular matrix in fibrosisAmerican Journal of Physiology-Heart and Circulatory Physiology, 2005
- Angiotensin AT2 receptor contributes to cardiovascular remodelling of aged rats during chronic AT1 receptor blockadeJournal of Molecular and Cellular Cardiology, 2004
- The influence of myocardial blood flow and volume of distribution on late Gd‐DTPA kinetics in ischemic heart failureJournal of Magnetic Resonance Imaging, 2004