Non-selective double inversion recovery pre-pulse for flow-independent black blood myocardial viability imaging
Journal of Cardiovascular Magnetic Resonance volume 12, Article number: P104 (2010)
MRI late gadolinium enhancement (LGE) using the inversion-recovery (IR) sequence is the current gold standard for assessing myocardial viability. Although it achieves high contrast between infarct and normal myocardium, there is often poor infarct-to-blood contrast. Flow-dependent and diffusion-prepared black-blood LGE techniques have previously been described.[1, 2] Recently a quadruple-inversion recovery pre-pulse was introduced for T1-independent flow suppression in carotid plaque imaging. We introduced a modification to this pre-pulse aiming to achieve flow-independent signal suppression over a wide user-defined T1-range and to improve sub-endocardial infarct detection in LGE myocardial viability imaging.
A non-selective double-inversion recovery (NS-DIR) sequence with two time delays, TI1 and TI2, was implemented on a 3 T Philips Achieva MR-scanner (Philips-Healthcare, Best, NL). TI1 and TI2 were optimized in MATLAB simulations by minimizing M Z NS-DIR over several user-defined T1-ranges for a given heart rate.
A T1-phantom containing 11 T1-samples (T1-range = 120 ms-1730 ms) was imaged with the NS-DIR pre-pulse using optimized TI1 and TI2 times. The signal-to-noise ratio (SNR) was calculated for each sample.
A 78-year-old man with previous myocardial infarctions was imaged with a 32-channel coil ~15 minutes after injection of 0.12 mmol/kg Gd-DOTA (Gadovist). Firstly a breath-hold 2D IR segmented gradient-echo (TFE) sequence was acquired in standard views. Imaging parameters included: spatial-resolution = 1.54 × 1.75 × 8 mm, TR/TE = 3.8 ms/2 ms, FA = 25°, TFE-factor = 25 and TI = 350 ms(chosen using LookLocker sequence).
Subsequently, identical planes were repeated with the IR replaced by the NS-DIR pre-pulse with imaging parameters maintained. TI1 = 411 ms and TI2 = 156 ms were used (optimized to minimize M Z NS-DIR for T1-range = 300-1400 ms, heart rate = 70 bpm).
Simulations & Phantom experiments
NS-DIR images demonstrate excellent signal suppression of blood and normal myocardium (Fig. 2a) while conventional IR-TFE images (Fig. 2b) display similar infarct and blood signal. Whilst both techniques demonstrate transmural anterior and inferior wall infarcts, the NS-DIR image depicts an apical, non-transmural sub-endocardial defect, which is difficult to distinguish from blood in the IR image.
We have developed a new flow-independent LGE sequence for improved contrast visualization. Simulations and phantom studies demonstrate excellent tissue suppression over a wide T1-range. Preliminary patient data suggests improved visualization of small sub-endocardial defects. Further studies are warranted to investigate the clinical usefulness of this novel approach.
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Peel, S.A., Jansen, C., Toussaint, N. et al. Non-selective double inversion recovery pre-pulse for flow-independent black blood myocardial viability imaging. J Cardiovasc Magn Reson 12 (Suppl 1), P104 (2010). https://doi.org/10.1186/1532-429X-12-S1-P104