Comparison of pilot tone-triggered and electrocardiogram-triggered cardiac magnetic resonance imaging: a prospective...

Electrocardiogram (ECG)-triggered cardiovascular magnetic resonance (CMR) can be challenging in patients with ECG unreliability. Pilot tone (PT)-triggered CMR may offer a reliable alternative.

To evaluate the feasibility of PT-triggered CMR and compare its performance with ECG-triggered imaging across various sequences in patients with common cardiovascular diseases.

This prospective study included 50 participants (26 males, 24 females; mean age 46.0±19.0y), including 15 with normal CMR findings and 35 with various cardiovascular diseases. All participants underwent both PT-triggered and ECG-triggered CMR on a 3T MRI system. Imaging included T2-weighted imaging (T2WI), T1-mapping, T2-mapping, cine, late gadolinium enhancement (LGE), and post-contrast T1-mapping sequences. Image quality and quantitative measurements were evaluated, including T2WI signal intensity, native T1-mapping, T2-mapping, and extracellular volume fraction (ECV) values, and comparative signal-to-noise ratio (compSNR) and comparative contrast-to-noise ratio (compCNR) of cine and LGE images, left/right ventricular function. Inter-reader agreement was evaluated using the intraclass correlation coefficient (ICC). Comparisons between the two methods were performed using paired t-test or the Wilcoxon signed-rank test.

No significant differences were observed in scanning times (p=.253-.864) or image quality (ICC: .589-1.000, p=.057-1.000) between PT- and ECG-triggered scans and images. Quantitative assessments showed good to excellent consistency (ICC=.843-.987). While PT-triggered LGE images showed higher compCNR (14.14±7.68 vs. 13.24±7.52, p=.016), other quantitative parameters showed no significant differences between PT- and ECG-triggered images. Six participants with hypertrophic cardiomyopathy or heart valve disease experienced false R-wave triggering during ECG gating, leading to motion artifacts, which were not visible in PT-triggered images.

PT-triggered cardiac MRI provides comparable image quality and quantitative assessments to ECG-triggered sequences and may offer advantages in minimizing motion artifacts, particularly in patients with conditions affecting ECG reliability, making it a promising alternative for cardiac MRI synchronization.