Abstract 11915: Clinical Gadolinium-Free Magnetic Resonance Imaging With Magnetization Transfer Contrast Detects Cardiac Fibrosis With High Sensitivity and Specificity Compared to Late Gadolinium Enhanced Imaging
Intro: Cardiac fibrosis identified by late gadolinium enhanced (LGE) cardiac MRI (CMR) is prognostic of adverse cardiac events, but is contraindicated in high-risk patients with impaired renal function. The signal intensity of balanced steady state free precession (bSSFP) CMR images is weighted by magnetization transfer (MT) from extracellular matrix macromolecules as a function of flip angle. We hypothesized that changes in the MT ratio (MTR) from pairs of differentially MT-weighted bSSFP cine images can enable identification of cardiac fibrosis without gadolinium.
Methods: Patients (n=47) referred for CMR were imaged on a 1.5T Siemens Aera scanner (Erlanger, Germany). Pairs of differentially MT-weighted bSSFP images (excitation flip angles of 5° or 45°), native T1 maps and T2 maps were acquired in one mid-ventricular slice. LGE images and post-contrast T1 maps were acquired after injection of gadolinium-DTPA (0.2 mmol/kg) and gadolinium partition coefficient (GPC) was calculated. MTR maps were calculated as (S45-S5)/S5*100 (%), where Sflip_angle is the voxel signal intensity. A feature tracking algorithm was used to measure peak endocardial circumferential strain, systolic and diastolic strain rates. Voxels were classified as healthy or enhanced at LGE and applied to maps of MTR, native T1, T2, and GPC for each patient.
Results: In 22 patients with fibrosis MTR maps and LGE revealed similar enhancement patterns (Fig A, B). Mean MTR, native T1, T2, and GPC were higher and peak strain was reduced in fibrotic tissue (p<0.05 healthy v. fibrotic for all). While MTR (R = 0.82), T1 (R = 0.55), and T2 (R = 0.75) correlated with GPC, receiver operating characteristic analysis revealed higher area under the curve values for MTR (0.96) compared to native T1 (0.78), T2 (0.84), peak strain (0.66), systolic (0.64) and diastolic (0.65) strain rates (Fig C, p<0.05 MTR v. all).
Conclusion: MT-weighted bSSFP cine CMR identified cardiac fibrosis comparable to LGE but without gadolinium.
Author Disclosures: T.A. Stromp: None. S.W. Leung: None. L. Jing: None. B.K. Fornwalt: None. V.L. Sorrell: None. M.H. Vandsburger: None.
- © 2014 by American Heart Association, Inc.