REPAIRit: Improving Myocardial Nulling and Ghosting Artifacts of 3D Navigator-Gated Late Gadolinium Enhancement Imaging During Arrhythmia.

BACKGROUND

Cardiac 3D navigator-gated late gadolinium enhancement (LGE) imaging is important for assessment of left atrial fibrosis, but the image quality is often degraded due to arrhythmia.

PURPOSE

To investigate a novel 3D LGE sequence with improved myocardial nulling and reduced ghosting artifacts during arrhythmia.

STUDY TYPE

Prospective.

POPULATION

Arrhythmia patients (n = 14).

SEQUENCE

The proposed technique, REPAIRit (Regrowth Equalization Pulse for Arrhythmias in Inversion Recovery with automatic inversion time calculation), inserts a saturation pulse with a dynamic flip angle into the 3D LGE sequence to minimize arrhythmia-induced signal fluctuations. Using ShMOLLI (shortened modified Look-Locker imaging) to estimate myocardial T , REPAIRit automatically calculates the optimal inversion time (TI) based on Bloch equations.

ASSESSMENT

REPAIRit LGE and the standard LGE were compared with simulations, phantom imaging, and patient studies. Patient images were assessed quantitatively, based on ghost-to-noise ratio (GNR), blood signal-to-noise ratio (SNRb), myocardial signal-to-noise ratio (SNRm), and blood-to-myocardium contrast-to-noise ratio (CNR), and qualitatively on a 4-point scale. Patients were subgrouped based on the presence of arrhythmia to assess the image quality difference.

STATISTICAL TESTS

The two LGE sequences were compared by Student's t-test and Wilcoxon signed-rank test. The two patient-subgroups were compared using Welch's t-test and Wilcoxon rank-sum test.

RESULTS

In 14 analyzed patients, REPAIRit LGE significantly lowered GNR (1.25 ± 0.41 vs. 1.42 ± 0.42, P = 0.04), reduced SNRm (1.90 ± 0.60 vs. 3.16 ± 1.66, P = 0.01), improved ghosting artifact scores (2.5 ± 0.6 vs. 2.2 ± 0.9, P = 0.03), myocardial nulling scores (2.7 ± 0.5 vs. 2.3 ± 0.7, P = 0.02), and atrial quality scores (2.8 ± 0.3 vs. 2.4 ± 0.8, P = 0.03) compared with the standard LGE. Comparing patients with arrhythmia (n = 6) to those without (n = 8) during the scan, the former had lower left ventricular (LV) myocardial T s (430 ± 26 msec vs. 469 ± 39 msec, P = 0.06) but similar blood T s (318 ± 55 msec vs. 316 ± 27 msec, P = 0.96), and significantly lower blood SNR (5.2 ± 1.8 vs. 9.2 ± 3.0, P = 0.01) and significantly worse image quality (P = 0.01 for REPAIRit and P = 0.03 for standard).

DATA CONCLUSION

REPAIRit improves myocardial nulling and reduces ghosting artifacts of 3D LGE under arrhythmia.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:688-699.