Compressed‐Sensing MP2RAGE sequence: Application to the detection of brain metastases in mice at 7T

Abstract

The CS-MP2RAGE sequence could be of great interest in oncology to either rapidly obtain mouse brain 3D T maps or to increase the spatial resolution with no penalty on the scan duration.

2D multislice MP2RAGE sequence for fast T1 mapping at 7 T: Application to mouse imaging and MR thermometry

“…Fast T 1 mapping of the whole mouse brain with the MS‐MP2RAGE sequence showed the ability to measure T 1 values with low variations along time (less than 1%). The in vivo T 1 values measured with the MS‐MP2RAGE sequence had to be corrected for the inversion efficiency, leading to values within the range found in the existing literature . This study highlights the potential of this sequence to be used during longitudinal studies.…”

“…Look‐Locker and fingerprinting sequences demand high computational requirements for generating the T 1 maps. Compared with 3D MP2RAGE approaches, the 2D encoding scheme drastically reduced the scan time of the MP2RAGE sequence, while maintaining accurate T 1 measurements. To further accelerate, using selective pulses, the dead times of the MP2RAGE sequence were used to acquire multiple slices.…”

“…To circumvent this issue, the TI 1 could be reduced to 800 ms. This would imply reducing the number of projections per GRE to 100, which could be compensated using either k‐space‐weighted image contrast, or compressed sensing . Still, if fat is the tissue of interest, TI 2 and MP2RAGE TR could also be reduced to 2400 and 7000 ms, respectively, which would improve the temporal resolution.…”

“…Another direction would be to use acceleration methods to acquire more slices in a single MP2RAGE TR . For instance, the GRE length could be shortened using undersampling, k‐space‐weighted image contrast, or compressed sensing, which could then be used to reduce aliasing artifacts. Parallel imaging would also enable simultaneous MS acquisition, thus extending applications of the MS‐MP2RAGE sequence to whole‐body T 1 mapping.…”

“…The magnetization‐prepared 2 rapid acquisition gradient echoes (MP2RAGE) sequence was initially developed for 3D acquisitions . It has been used for brain T 1 mapping in humans and small animals, at 3 T and 7 T. Its combination with compressed sensing or EPI encoding has enabled faster acquisitions, such as whole human brain mapping, in approximately 3 minutes . In parallel, its implementation with radial encoding has been used for mouse abdominal T 1 maps, with high robustness to motion and to acceleration using undersampling .…”