Radial MP2RAGE sequence for rapid 3D T1 mapping of mouse abdomen: application to hepatic metastases
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The T1 longitudinal recovery time is regarded as a biomarker of cancer treatment efficiency. In this scope, the Magnetization Prepared 2 RApid Gradient Echo (MP2RAGE) sequence relevantly complies with fast 3D T1 mapping. Nevertheless, with its Cartesian encoding scheme, it is very sensitive to respiratory motion. Consequently, a radial encoding scheme was implemented for the detection and T1 measurement of hepatic metastases in mice at 7T.
A 3D radial encoding scheme was developed using a golden angle distribution for the k-space trajectories. As in that case, each projection contributes to the image contrast, the signal equations had to be modified. Phantoms containing increasing gadoteridol concentrations were used to determine the accuracy of the sequence in vitro. Healthy mice were repetitively scanned to assess the reproducibility of the T1 values. The growth of hepatic metastases was monitored. Undersampling robustness was also evaluated.
The accuracy of the T1 values obtained with the radial MP2RAGE sequence was > 90% compared to the Inversion-Recovery sequence. The motion robustness of this new sequence also enabled repeatable T1 measurements on abdominal organs. Hepatic metastases of less than 1-mm diameter were easily detected and T1 heterogeneities within the metastasis and between the metastases within the same animal were measured. With a twofold acceleration factor using undersampling, high-quality 3D T1 abdominal maps were achieved in 9 min.
The radial MP2RAGE sequence could be used for fast 3D T1 mapping, to detect and characterize metastases in regions subjected to respiratory motion.
• The Cartesian encoding of the MP2RAGE sequence was modified to a radial encoding. The modified sequence enabled accurate T 1 measurements on phantoms and on abdominal organs of mice.
• Hepatic metastases were easily detected due to high contrast. Heterogeneity in T 1 was measured within the metastases and between each metastasis within the same animal.
• As implementation of this sequence does not require specific hardware, we expect that it could be readily available for clinical practice in humans.
KeywordsMagnetic resonance imaging Mice Three-dimensional imaging Liver Metastasis
Balanced steady-state free precession
Magnetization Prepared 2 RApid Gradient Echoes
This study has received funding by the Laboratory of Excellence TRAIL ANR-10-LABX-57.
Compliance with ethical standards
The scientific guarantor of this publication is Emeline J Ribot.
Conflict of interest
The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.
Statistics and biometry
No complex statistical methods were necessary for this paper.
Approval from the Animal Care and Use Institutional ethics committee of Bordeaux was obtained.
• performed at one institution
- 12.Stikov N, Boudreau M, Levesque IR, Tardif C, Barral K, Pike GB (2015) On the accuracy of T1 mapping: searching for common ground. Magn Reson Med 522:514–522Google Scholar
- 14.Næss-Schmidt ET, Tietze A, Mikkelsen IK et al (2015) Patch-based segmentation from MP2RAGE images: comparison to conventional techniques. First International Workshop on Patch-based Techniques in Medical Images (Patch-MI 2015), Oct 2015, Munich, Germany. Patch-Based Techniques in Medical Imaging First International Work- shop, Patch-MI 2015, held in conjunction with MICCAI 2015, Munich, Germany, October 9, 2015, Revised Selected Papers, 9467, pp.180-187, 2016, Lecture Notes in Computer Science. <10.1007/978-3-319-28194-0 22>. <hal-01290510>Google Scholar
- 28.Kecskemeti S, Samsonov A, Hurley SA, Dean DC, Field A, Alexander AL (2016) MPnRAGE: a technique to simultaneously acquire hundreds of differently contrasted MPRAGE images with applications to quantitative T1 mapping. Magn Reson Med 75:1040–1053Google Scholar