Rapid Fire Abstracts
Moezedin javad Rafiee, MD
Research associate
Research Institute of the McGill University Health Center, Canada
Moezedin javad Rafiee, MD
Research associate
Research Institute of the McGill University Health Center, Canada
Leila Haririsanati, MD, MSc
Researcher
McGill University Health Center, Canada
Margherita Leo
Cardiac MRI Technologist
Research Institute of the McGill University Health Center, Canada
Sylvie Galineau, MRT
Technologist
Research Institute of the McGill University Health Center, Canada
Matthias G. Friedrich, MD
Full Professor
McGill University Health Centre
Mc Gill University, Canada
Michael Chetrit, MD
Assistant professor
McGill University Health Center, Canada
Cardiac magnetic resonance imaging (CMR) using myocardial mapping is a comprehensive, non-invasive method for assessing tissue pathology in cardiac diseases (1). The diagnostic sensitivity, however, may be compromised by various artifacts that can degrade image quality and alter quantitative results (2). A common source of such artifacts is a noisy ECG signal (3), which leads to inconsistent triggering. Peripheral pulse gating (PG) may overcome this problem by relying on the more stable peripheral pulse only (Fig 1). The long and variable delay between cardiac contraction and the arrival of the pulse wave at the finger are matters of concern (4). Consequently, the technique is not that widely used and neither its accuracy nor reference values for T1 and T2 mapping have been determined based on pulse-triggered mapping.
Methods:
This retrospective study aimed to compare T1 and T2 values obtained using PG and ECG gating methods on a 3Tesla scanner head-to-head.
We hypothesized that in severe arrhythmia and unpredictable cardiac rhythms, where ECG-triggered T1 and T2 mapping is challenging, PG can provide a feasible and reliable alternative.
Forty-one healthy participants (63% female, mean age 55 years) were scanned on a 3T SIGNA Premier (GE Healthcare, Milwaukee, USA). Two successive slices were acquired in the mid-third short-axis orientation using ECG- and peripheral pulse-gated (PG) MOLLI-MOCO-DL T1 (Modified Look-Locker Inversion recovery with Motion Correction with deep learning) and FSE-T2 (Double inversion recovery prepared or black- blood fast spin echo) sequences as standard method. Mid-myocardial T1 and T2 values were measured using cvi42™ (Circle Cardiovascular Imaging Inc, Calgary, Canada) for each T1 and T2 map, employing a blinded, cross-sectional analysis. An experienced reader applied a 4-point Likert scale to evaluate image quality (IQ) in both methods 1 = non-diagnostic IQ, 2 = diagnostic IQ with many artifacts, 3 = diagnostic IQ with few artifacts, and 4 = perfect IQ. A Mann-Whitney U-test was applied to compare groups.
Results: There were no significant differences between ECG-gating and PG-gating in T1 and T2 mapping values. The median T1 mapping value was 1186±81.5 ms for ECG-gating compared to 1193±79 ms for the PG technique (p = 0.8; Fig. 2A). The median T2 -value was 46±10 ms for ECG-gating compared to 47±9 ms for PG-gating (p = 0.79; Fig. 2B). The image quality of the T1 and T2 mapping using the PG-gating technique was diagnostic with few artifacts in 27% of participants (n=11), and perfect in 73% (n=30). The image quality of the ECG-gating technique was diagnostic with few artifacts in 21.9% of participants (n=9), and perfect in 78% (n=32) (Fig 3).
Conclusion:
Using peripheral pulse gating for T1 and T2 mapping is feasible and reliable. It should be used whenever ECG-gating is challenging.
