- Workshop presentation
- Open Access
Validation of a T1 and T2 mapping software for quantitative MRI
https://doi.org/10.1186/1532-429X-18-S1-W28
© Bidhult et al. 2016
- Published: 27 January 2016
Keywords
- Spin Echo Sequence
- Relaxation Time Estimate
- bSSFP Sequence
- Myocardial Extracellular Volume
- Phantom Validation
Background
Methods
Table 1
Supported Signal models | ||
---|---|---|
Supported sequence-type | 3-parameter models | 2-parameter models |
T1 Inversion-Recovery (MAGIR) | S(t) = |A (1 - B exp(-t/T1))| | S(t) = |A (1 - 2 exp(-t/T1))| |
T1 Phase-Sensitive Inversion-Recovery (PSIR) | S(t) = A (1 - B exp(-t/T1)) | S(t) = A (1 - 2 exp(-t/T1)) |
T1 Saturation Recovery | S(t) = A (1 - B exp(-t/T1)) | S(t) = A (1 - exp(-t/T1)) |
T1 MOLLI/T1 Look-Locker MAG-images | S(t) = |A (1 - B exp(-t/T1*))|; T1 = T1*(B - 1) | not available |
T1 MOLLI/T1 Look-Locker PSIR-images | S(t) = A (1 - B exp(-t/T1*)); T1 = T1*(B - 1) | not available |
T2 Spin-Echo (Multi-Echo or Single-Echo) | S(t) = A exp(-t/T2) + B; B > 0 | S(t) = A exp(-t/T2) |
T2-prepared bSSFP | S(t) = A exp(-t/T2) + B; B > 0 | S(t) = A exp(-t/T2) |
The proposed modules generated relaxation time maps from two free-breathing, single-shot bSSFP sequences. Saturation-Recovery (SR) and T2-preparation prepulses were used to create T1 & T2 weighting. Apart from T2-prepared images, a saturation prepared image was used in the T2 estimates, as previously proposed [4]. In addition, T1 was estimated with MOLLI at 1.5T using 5(3b)3 and 4(1b)3(1b)2 schemes. Acquisition times for the three bSSFP sequences were 13 min 15 sec for T1-SR, 11 sec for T1-MOLLI and 14 min 3 sec for the T2 sequence. Bias and Variability were determined using modified Bland-Altman analysis. Error percentages were computed by dividing the difference between the evaluated method and the reference with the reference value.
Results
The left panel shows modified Bland-Altman analysis of the phantom validation and the right panel shows corresponding T1 & T2 estimation examples from two phantoms. Left panel: Crosses indicate data-points, the solid lines indicate bias and the dotted lines correspond to bias +- 1.96 SD (Standard Deviation). Right panel: Solid lines represent estimated relaxation curves and blue circles indicate data-points.
Conclusions
A T1 & T2 mapping software was developed and evaluated. Low bias and variability was found for the T1-SR sequence. The increased variability of MOLLI compared to the SR sequence may be explained by the reduced number of sampling points used in MOLLI and an increasing T1 error for low T2 values. The increased variability of the T2-prepared sequence may be explained by limited SNR.
Authors’ Affiliations
References
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Copyright
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.