Native T1 mapping in patients with idiopathic dilated cardiomyopathy for the assessment of diffuse myocardial fibrosis: validation against histologic endomyocardial biopsy
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KeywordsDilate Cardiomyopathy Late Gadolinium Enhancement Invasive Coronary Angiography Endomyocardial Biopsy Collagen Volume Fraction
Late gadolinium enhancement (LGE) MRI provides a significant impact on prognosis in dilated cardiomyopathy (DCM) patients. However, LGE MRI is less suitable for quantifying the degree of fibrosis in diffusely diseased myocardium. T1 mapping technique allows for the quantitative assessment of extracellular volume fraction (ECV), which has been histologically validated against the collagen volume fraction (CVF). Native myocardial T1 also has a potential for the noninvasive detection of myocardial fibrosis. Recent study demonstrated that native myocardial T1 permits the discrimination between normal and diffusely diseased myocardium accurately in DCM patients. However, in-vivo histological validation of native myocardial T1 in DCM patients is still lacking. The aim of this study was to histologically validate native myocardial T1 for the assessment of diffuse myocardial fibrosis in DCM patients.
Twenty DCM patients (18 men, 56.8±15.7 years old) underwent CMR including cine, LGE MRI and pre- and post-contrast T1 mapping using a modified Look-Locker inversion recovery sequence at 3T. A significant coronary artery disease was excluded by invasive coronary angiography in all patients. All patients underwent endomyocardial biopsies from right septal ventricle. The diagnosis of DCM was confirmed histologically in all patients. T1 values were quantified within the septal myocardium and LV blood pool with a heart rate correction. ECV was calculated from myocardial and blood T1 measured before and after the administration of gadolinium contrast medium and hematocrit measures. CVF was quantified histologically from biopsy specimens using picrosirius red staining.
The current results demonstrated that both native T1 and ECV have a good correlation with histological collagen fraction in DCM patients. Native T1 mapping may serve as a noninvasive technique that allows for quantitative assessment of diffuse myocardial fibrosis in DCM patients without administrating gadolinium contrast medium.
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