3D Free-breathing Simultaneous Grey-blood Late Gadolinium Enhancement and MR Angiography (RF_TH_206)

Background: CMR provides multi-contrast images for the assessment of different cardiac diseases. Late gadolinium enhancement (LGE) imaging is the gold standard for non-invasive myocardial tissue characterization [1], while cardiac MR angiography (CMRA) provides anatomical information of the heart and coronary arteries [2]. As the performance of LGE is dependent on image contrast between tissues, different LGE techniques with optimized contrast have been proposed [3]. A grey-blood (GB) LGE sequence has previously been proposed without additional preparation pulses other than inversion recovery (IR), which demonstrated robust results in scar depiction with increased contrast between scar, normal myocardium, and blood than conventional bright-blood (BB) LGE [4,5]. In this study, we aim to integrate 3D GB-LGE with CMRA by proposing a simultaneous Grey-Blood and Bright-blOOd phase SensiTive inversion recovery (GB-BOOST) sequence.

Methods: The proposed GB-BOOST sequence acquires two interleaved 3D volumes using Dixon GRE acquisition with IR and T2 preparation (T2prep, 50ms duration) respectively (Fig. 1). The inversion time (TI) is set to null blood signal using subject-specific Bloch equation simulation. Image navigator (iNAV) enables 100% respiratory scan efficiency [6]. A variable-density Cartesian trajectory with spiral-like profile order and golden-angle step is adopted with 5-fold undersampling [7]. Inline non-rigid motion corrected iterative SENSE reconstruction and water/fat separation is performed followed by offline high-dimensional patch-based low-rank regularization (HD-PROST) denoising and phase-sensitive inversion recovery (PSIR) reconstruction [5,8,9].
Clinical breath-held 2D BB- and GB-PSIR, and free-breathing 3D GB-BOOST and CMRA were sequentially scanned on 3 female patients (56±7 years) approximately 10-20 mins after the injection of contrast (gadobutrol, Gadovist, Bayer Healthcare) at a dose of 0.15 mmol/kg using a 3T MR scanner (MAGNETOM Vida, Siemens Healthineers, Erlangen, Germany). 3D sequences are performed with resolution = 1.2 mm³, TR/TE1/TE2 = 5.23/1.67/3.18 ms, bandwidth=827Hz/pixel.

Results: The 3D GB-BOOST sequence was successfully performed on the three subjects in 8.4±0.9 mins with average heart rate of 62±5 bpm. Representative images from one patient show that 3D PSIR GB-BOOST is consistent with 2D BB- and GB-PSIR for the detection of scar area, while 3D PSIR GB-BOOST provides better contrast between scar and blood (Fig. 2). Curved planner reconstruction of LAD coronary artery of another patient is shown in Fig. 3. Visual comparison indicates that 3D T2prep GB-BOOST provides comparable image quality and contrast compared with 3D CMRA images.

Conclusion: The proposed 3D GB-BOOST sequence can achieve simultaneous GB-PSIR and CMRA in a single fast scan. 3D PSIR GB-BOOST achieves better contrast between scar and blood than the clinical 2D PSIR sequences, and 3D T2prep GB-BOOST is comparable with 3DCMRA for the depiction of the coronary arteries. The promising results warrant further experiments in a larger patient cohort and quantitative analysis.