- Walking poster presentation
- Open Access
Characterization of the ultra-short echo time magnetic resonance (UTE MR) collagen signal associated with myocardial fibrosis
© Siu et al; licensee BioMed Central Ltd. 2015
- Published: 3 February 2015
- Resonance Frequency
- Late Gadolinium Enhancement
- Myocardial Fibrosis
- Collagen Solution
- Collagen Signal
The homogeneous distribution of collagen in diffuse myocardial fibrosis renders the disease unsuitable for imaging using late gadolinium enhancement (LGE) . More recently, the estimation of extracellular volume from T1 maps involving gadolinium agents has shown promise; however, these methods are not specific to collagen and are governed by gadolinium kinetics . The diagnosis of diffuse myocardial fibrosis would benefit from an imaging method that can directly detect collagen. Notably, ultra-short echo time magnetic resonance (UTE MR) is a technique that can be used to detect short T2* species, including collagen . Our objective is to characterize the UTE signal of protons in the collagen molecule, including their T2* and chemical shift. Direct isolation of a collagen signal could aid in the diagnosis of myocardial fibrosis, especially for diffuse distributions, and the assessment of disease extent.
Collagen solutions of concentrations ranging from 0 % m/v to 50 % m/v were prepared by dissolving hydrolyzed type I and III collagen powder in 0.125 mM MnCl2 , where the signal decay of MnCl2 mimicked that of cardiac muscle. Each solution was scanned using a 3D UTE pulse sequence at 7 T, acquiring TEs from 0.02 ms to 25 ms, at a resolution of 0.781 mm isotropic. Upon fitting with a model of bi-exponential T2* with oscillation, the UTE collagen signal fraction was determined and calibrated against the collagen concentration. The T2* and resonance frequency (arising from the chemical shift) of collagen were assessed in collagen solutions. Validation of the collagen signal properties was also performed in formalin-fixed canine heart tissue, imaged with TEs from 0.02 ms to 25 ms, at a resolution of 0.156 mm isotropic.
The results suggest that collagen associated with myocardial fibrosis can be endogenously detected and quantified using UTE MRI. This signal is specific to protons in collagen, characterized by a T2* of ~ 0.8 ms and a resonance frequency of ~ 1.1 kHz upfield of water at 7 T. Such properties would be beneficial in the determination of collagen content due to disease.
Canadian Institutes of Health Research (CIHR).
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.