Evaluation of a free-breathing myocardial T1 mapping using magnetization-prepared slice interleaved spoiled gradient echo imaging in patient
Journal of Cardiovascular Magnetic Resonance volume 17, Article number: Q130 (2015)
Quantitative myocardial T1 mapping shows promise for assessment of various cardiomyopathies. Most available sequences are generally acquired within a breath-hold using a balanced SSFP (bSSFP) imaging readout. However, the signal obtained from a bSSFP imaging readout is T2 dependent, sensitive to magnetization transfer and has increased susceptibility to the B0 field inhomogeneity leading to regional variations in T1 estimates (1). Recently, we developed a novel T1 mapping sequence for free-breathing, multi-slice, myocardial T1 mapping using a slice-interleaved T1 sequence with spoiled gradient echo (GRE) imaging readout. However, the feasibility of this sequence in patient has not yet been studied. In this study, we sought to demonstrate the feasibility of this sequence in patients and its ability to detect abnormal T1 times.
Sixteen patients referred to clinical CMR for assessment of cardiomyopathy (54±21y, 13 m) and eleven control healthy adult subjects (35±21y, 4 m) were recruited for this study. Subjects were scanned on a 1.5 T Philips scanner. Native T1 mapping was performed using a free-breathing slice interleaved acquisition which enables simultaneous acquisition of 5 slices using multiple inversion recovery (IR) experiments (2). All the 5 slices are acquired once in each IR experiment, which enables the sampling of the undisturbed T1 recovery curve. Each T1-weighted image was acquired using an ECG-triggered acquisition with a GRE imaging readout (TR/TE/α=4.3/2.1ms/10˚, FOV=280×272 mm2, voxel size=2×2 mm2, slice thickness=8 mm, 5 slices, number of phase-encoding lines=43, linear ordering, 10 linear ramp-up pulses, SENSE factor=2.5, half Fourier=0.75, bandwidth=382Hz/pixel). Prospective slice tracking was combined with retrospective image registration to correct for respiratory motion. Myocardial native T1 values were evaluated using a 16 myocardial segment model for all healthy subjects and patients.
Native T1 times in the healthy subject control group were 1094±24ms. Figure 1 shows an example of native T1 maps obtained in three patients where native T1 times (1114ms, 1086ms, and 1111ms) were in the same range as in the healthy subject control group. Homogeneous and consistent T1 times were obtained over the whole myocardium in these patients and the visual quality of T1 map was excellent. Figure 2 shows an example of native T1 maps obtained in two patients where elevated T1 times can be observed (1197ms and 1158ms). Elevated T1 times were consistent across multiple myocardial segments.
Free-breathing myocardial T1 mapping using magnetization-prepared slice interleaved spoiled gradient echo imaging is feasible in patients and provides excellent T1 map quality which enables the detection of altered native T1 times in the presence of specific cardiomyopathies.
Kellman : JCMR. 2013
Weingärtner : MRM. 2014
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Jang, J., Roujol, S., Basha, T.A. et al. Evaluation of a free-breathing myocardial T1 mapping using magnetization-prepared slice interleaved spoiled gradient echo imaging in patient. J Cardiovasc Magn Reson 17 (Suppl 1), Q130 (2015). https://doi.org/10.1186/1532-429X-17-S1-Q130