- Workshop presentation
Reproducibility of free-breathing multi-slice native myocardial T1 mapping using the slice-interleaved T1 (STONE) sequence
Journal of Cardiovascular Magnetic Resonancevolume 17, Article number: W29 (2015)
Quantitative myocardial T1 mapping is a promising technique for assessment of interstitial diffuse fibrosis. Recently, a novel T1 mapping sequence for free-breathing, multi-slice, myocardial T1 mapping using the slice-interleaved T1 (STONE) has been developed , which was shown to provide superior accuracy compared to MOLLI . However, in-vivo reproducibility and precision of this sequence was not studied. In this study, we sought to investigate the reproducibility and precision of the STONE sequence for in-vivo native myocardial T1 measurement.
Nine healthy adult subjects (37±22y, 4 m) were scanned on a 1.5 T Philips scanner using the STONE T1 mapping sequence. The STONE sequence enables sampling of the undisturbed T1 recovery curve by selectively exciting each slice once after a single nonselective inversion pulse. The STONE sequence was implemented using a b-SSFP imaging readout and the following parameters: TR/TE=2.8/1.41ms, flip angle=70˚, FOV=280×272 mm2, voxel size=2×2 mm2, slice thickness=8 mm, 5 slices, slice gap=8mm, number of phase-encoding lines=43, linear ordering, 10 linear ramp-up pulses, SENSE factor=2.5, half Fourier=0.75. To compensate for respiratory motion, prospective slice tracking was combined with retrospective in-plane image registration . The STONE sequence was compared to a single slice breath-hold MOLLI sequence which was acquired with a 5-(3)-3 scheme and similar imaging parameters. The single slice of the MOLLI corresponded to the middle slice of the STONE, which represented the mid left ventricle. Both sequences were acquired 5 times repeatedly for each subject. In-vivo measurement, precision (i.e. spatial variability) and reproducibility of T1 values were evaluated based on a 16 myocardial segment model for STONE and a 6 myocardial segment model for MOLLI. Precision was defined as the standard deviation of T1 values over each segment. Reproducibility was defined as the standard deviation of the T1 values over the 5 repeated scans within each segment. A paired t-test was performed on the measures of the mid left ventricle slice of STONE and MOLLI to assess for statistical significant differences between the two sequences.
Figure 1 shows an example of T1 maps obtained in one subject. Homogenous T1 signals were obtained over all myocardial segments, slices, and repetitions. The STONE sequence showed higher T1 values (1087±35ms vs. 1010±36ms, p<0.001), higher precision (52±11ms vs. 61±16ms, p=0.001), and similar reproducibility (23±13ms vs. 17±11ms, p=0.18) than MOLLI (Figure 2).
The STONE sequence yields higher T1 times, higher precision and similar reproducibility than MOLLI for in-vivo native T1 mapping.
Weingärtner : MRM. 2014
Messroghli : MRM. 2004
Roujol : MRM. 2014