Reproducibility of slice-interleaved myocardial T2 mapping sequences
Journal of Cardiovascular Magnetic Resonance volume 18, Article number: P54 (2016)
Myocardial T2 mapping sequence allows quantitative assessment of myocardial edema and inflammation. Commonly, a series of T2 weighted images with steady-state free-precession (SSFP) are acquired after T2 magnetization preparation (T2Prep) with different echo times. Conventionally, a single slice per breath-hold is acquired to image one single slice. Because inflammation/edema is often regional, multiple breath-holds are needed to cover the entire ventricle. The slice-interleaved T2 mapping sequence was recently proposed to image multiple slices in a single scan by using a slice-selective T2Prep. While accuracy of this sequence to quantify T2 was previously studied, the measurement reproducibility is not known. Therefore, we sought to investigate the reproducibility of myocardial T2 mapping using the slice-interleaved T2 mapping sequence.
Eleven healthy subjects (age: 33 ± 16 years, 6 males) were imaged on 2 different days with the same scan protocol using a 1.5T MRI scanner (Philips Achieva). On each day, slice-interleaved T2 sequence was repeated twice. Subsequently, subjects were removed from the scanner and repositioned, followed by another 2 repetitions of the same scan. The following imaging parameters were used: In-plane resolution = 2.1 × 2.1 mm2, slice thickness = 8 mm, slice gap = 4 mm, Field of View = 320 × 320 mm2, TR/TE/α = 2.8 msec. / 1.38 msec. /55°, SENSE-rate = 2.3, and acquisition window = 191 ms, bandwidth = 1879.7 Hz/pixel. Motion correction was performed between different images. T2 maps were calculated using a 3-parameter fit model. The epicardial and endocardial contours in the left ventricle were manually drawn in 5 short axis-slices to calculate global and slice-based myocardial T2 values. Coefficient of variation (CV) analysis for each slice was generated to assess the variability. Bland-Altman plots were used to test for significant differences between repetitions, sessions and days.
Figure 1 shows mean T2 values for different imaging sessions, averaged over all subjects and low CVs between subjects (7.2 ± 4.3%). There were low CVs between days (6.3 ± 4.0%) and between sessions (5.0 ± 4.3%). Fig. 2 shows Bland-Altman plots for T2 values between first scan of day 1 and day 2 (A), between first scan of session 1 and session 2 (B), and between scan 1 and 2 within each first session (C).
Slice-Interleaved T2 mapping sequence yields reproducible T2 measurements with highest CV of 7.2 ± 4.3% for between day scans.
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Bellm, S., Basha, T., Ngo, L. et al. Reproducibility of slice-interleaved myocardial T2 mapping sequences. J Cardiovasc Magn Reson 18 (Suppl 1), P54 (2016). https://doi.org/10.1186/1532-429X-18-S1-P54