What is the clinical evidence from this study?

Study design: Other. Population: Healthy subjects (n=11). Intervention: Pilot tone-based prospective respiratory motion correction vs. Uncorrected free-breathing T1 mapping. Primary outcome: Difference in T1 values compared to breathhold T1 maps (p=<0.05).

August 3, 2022Open Access

Pilot tone-based prospective correction of respiratory motion for free-breathing myocardial T1 mapping

Q: What are the key findings of this study?

Pilot tone-based prospective motion correction reduced the overestimation of myocardial T1 values during free-breathing from 26% to 3% compared to breathhold T1 maps.

Q: What does this research mean for the field?

A pilot tone-based motion correction approach enables free-breathing myocardial T1 mapping with accuracy comparable to standard breathhold techniques. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Key Result

Pilot tone-based prospective motion correction reduced the overestimation of myocardial T1 values during free-breathing from 26% to 3% compared to breathhold T1 maps.

Structured PICO

Does pilot tone-based prospective respiratory motion correction improve the accuracy of free-breathing myocardial T1 mapping compared to uncorrected scans in healthy subjects?

Population

11 healthy subjects (7 male, 4 female, age 30 ± 7 years old, weight 72 ± 11 kg) and a motion phantom.

Intervention

Pilot tone (PT)-based prospective respiratory motion correction for free-breathing myocardial T1 mapping using a continuous golden-angle radial acquisition.

Comparator

Non-motion corrected free-breathing T1 mapping and standard breathhold T1 mapping (reference).

Outcome

T1 mapping accuracy (difference in T1 values compared to reference breathhold data).surrogate

Pilot tone-based prospective motion correction enables free-breathing myocardial T1 mapping with accuracy comparable to standard breathhold techniques.

Main Result

Absolute Event Rate: 3% vs 26%

p-value: p=<0.05

Limitations

Rigid motion correction was only performed for head-feet and anterior-posterior directions, omitting right-left motion.
The same motion model was used for inspiration and expiration without exploring hysteresis effects.
The motion model was derived from a specific heart region but applied globally, potentially causing artifacts in surrounding tissues.
The study was conducted in a small number of healthy subjects, requiring further validation in patients with cardiac disease.

Abstract

OBJECTIVE: To provide respiratory motion correction for free-breathing myocardial T1 mapping using a pilot tone (PT) and a continuous golden-angle radial acquisition. MATERIALS AND METHODS: During a 45 s prescan the PT is acquired together with a dynamic sagittal image covering multiple respiratory cycles. From these images, the respiratory heart motion in head-feet and anterior-posterior direction is estimated and two linear models are derived between the PT and heart motion. In the following scan through-plane motion is corrected prospectively with slice tracking based on the PT. In-plane motion is corrected for retrospectively. Our method was evaluated on a motion phantom and 11 healthy subjects. RESULTS: Non-motion corrected measurements using a moving phantom showed T1 errors of 14 ± 4% (p < 0.05) compared to a reference measurement. The proposed motion correction approach reduced this error to 3 ± 4% (p < 0.05). In vivo the respiratory motion led to an overestimation of T1 values by 26 ± 31% compared to breathhold T1 maps, which was successfully corrected to an average difference of 3 ± 2% (p < 0.05) between our free-breathing approach and breathhold data. DISCUSSION: Our proposed PT-based motion correction approach allows for T1 mapping during free-breathing with the same accuracy as a corresponding breathhold T1 mapping scan.

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