Cardiac magnetic resonance imaging of myocardial contrast uptake and blood flow in patients affected with idiopathic or familial dilated cardiomyopathy

Abstract

Idiopathic dilated cardiomyopathy (IDC) is characterized by left ventricular (LV) enlargement with systolic dysfunction, other causes excluded. When inherited, it represents familial dilated cardiomyopathy (FDC). We hypothesized that IDC or FDC would show with cardiac magnetic resonance (CMR) increased myocardial accumulation of gadolinium contrast at steady state and decreased baseline myocardial blood flow (MBF) due to structural alterations of the extracellular matrix compared with normal myocardium. CMR was performed in nine persons affected with IDC/FDC. Healthy controls came from the general population (n = 6) or were unaffected family members of FDC patients (n = 3) without signs or symptoms of IDC/FDC or any structural cardiac abnormalities. The myocardial partition coefficient for gadolinium contrast (lambda(Gd)) was determined by T1 measurements. LV shape and function and MBF were assessed by standard CMR methods. lambda(Gd) was elevated in IDC/FDC patients vs. healthy controls (lambda(Gd) = 0.56 +/- 0.15 vs. 0.41 +/- 0.06; P = 0.002), and correlated with LV enlargement (r = 0.61 for lambda(Gd) vs. end-diastolic volume indexed by height; P < 0.01) and with ejection fraction (r = -0.80; P < 0.001). The extracellular volume fraction was higher in IDC patients than in healthy controls (0.31 +/- 0.05 vs. 0.24 +/- 0.03; P = 0.002). Resting MBF was lower in IDC patients (0.64 +/- 0.13 vs. 0.91 +/- 0.22; P = 0.01) than unaffected controls and correlated with both the partition coefficient (r = -0.57; P = 0.012) and the extracellular volume fraction (r = -0.56; P = 0.019). The expansion of the extracellular space correlated with reduced MBF and ventricular dilation. Expansion of the extracellular matrix may be a key contributor to contractile dysfunction in IDC patients.

Equilibrium Contrast Cardiovascular Magnetic Resonance for the Measurement of Diffuse Myocardial Fibrosis

“…32,33 Recently, mathematical modeling of this effect has been used to derive partition coefficient estimates. 25 Contrast has been used as a continuous infusion instead of a bolus to image focal scar, 34 to measure the scar partition coefficient, 7 and in autopsy samples to measure the contrast volume of distribution of diffuse fibrosis, 24 but it has not been used in vivo. In this study we used a primed continuous infusion (removing contrast kinetic effects), a direct blood volume of distribution measure (1Ϫhematocrit) to obtain Vd (m) rather than partition coefficient, and measured diffuse fibrosis in vivo.…”

Molecular Imaging of the Cardiac Extracellular Matrix

“…39 ECV is determined by calculating the volume of 20 Normal ECV is generally in the range of 24% to 28%. 40 The measurement of ECV and V d has been performed in several myocardial conditions to assess fibrosis, including dilated cardiomyopathy, 41 aortic stenosis, and hypertrophic cardiomyopathy. 42 V d measured by T1 mapping in aortic stenosis and hypertrophic cardiomyopathy correlated strongly with histological measures in surgical biopsy with r 2 values of 0.86 and 0.62, respectively.…”

Comprehensive Cardiovascular Magnetic Resonance Assessment in Patients With Sarcoidosis and Preserved Left Ventricular Ejection Fraction

“…14,15 Short-axis T2 mapping was performed in a matching midventricular short axis before the administration of contrast agent using an ECG-triggered T2-prepared single-shot balanced steady-state free precession prototype sequence with multiple T2 preparation times. 16 More detailed information on CMR protocol is provided in the Table I in the Data Supplement.…”