- Oral presentation
- Open Access
Quantitative free-breathing 3T T2-mapping of the heart designed for longitudinal studies
© Van Heeswijk et al; licensee BioMed Central Ltd. 2012
- Published: 1 February 2012
- Empirical Equation
- Bloch Equation
- Subacute Phase
- Phantom Scan
- bSSFP Imaging
Recently, T2-weighted MRI for the characterization of edema after myocardial infarction has attracted considerable attention (Friedrich, NatRevCardiol2010). Furthermore, the recently proposed combination of bSSFP imaging and T2Prep for T2-mapping at 1.5T has enabled a rapid quantitative cardiac T2 estimation (Huang et al., MRM2007). However, the accuracy of this method may still be limited due to the complex T2/T1 signal weighting. Especially for longitudinal studies designed for monitoring and/or guiding therapy, accurate and reproducible T2 measurements will be critical. A novel quantitative 3T T2-mapping protocol was therefore developed and tested in both healthy volunteers and patients.
An adiabatic T2prep with 3 incremental TE values, affine coregistration, a navigator and 2D radial gradient echo imaging were combined for free-breathing T2-mapping at 3T with a spatial resolution of 1.25mm. Bloch equation simulations of this sequence were used to optimize scan parameters and to determine an empirical equation that compensates for T1 relaxation and which returns the “true” T2. The T2-mapping sequence and empirical equation were then validated in a series of 15 phantoms in which the true T2 was determined with a 9-TE spin-echo sequence. Next, the myocardial short axis T2 of 8 healthy volunteers was mapped in two different scan sessions while a reference phantom (T2=43.1±0.7ms) was placed next to the thorax. The average myocardial T2 for both sessions was computed with and without correction with the “true” reference phantom T2. Finally, this validated protocol was used in 5 patients in the subacute phase after revascularization of acute ST-elevation myocardial infarctions and compared to T2-weighted TSE imaging.
The methodology presented in this study enables robust and accurate cardiac T2-mapping at 3T, while the addition of a reference phantom improves reproducibility. Therefore, it may be well-suited for longitudinal studies in patients with ischemic heart disease.
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/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.