Improved respiratory navigator gating for thoracic 4D flow MRI.

Area of Science:

• Medical Imaging
• Cardiovascular Imaging
• Magnetic Resonance Imaging

Background:

• Thoracic and abdominal 4D flow MRI relies on navigator respiration control, leading to variable scan efficiency and total scan time.
• Inter-individual breathing pattern variability complicates scan time predictability.

Purpose of the Study:

• To evaluate a novel respiratory control strategy for 4D flow MRI.
• The strategy utilizes diaphragm navigator gating with fixed scan efficiency (Seff), respiratory-driven phase encoding, and navigator training.

Main Methods:

• 10 healthy subjects underwent 4D flow MRI of the thoracic aorta at 1.5T and 3T.
• Four scans were acquired: conventional gating and new methods with fixed Seff (60%, 80%, 100%).
• Image quality and 3D systolic flow velocity vector fields were compared.

Main Results:

• The new method achieved predictable scan times with stable Seff, independent of breathing patterns.
• Image quality and 3D systolic velocities showed good agreement with conventional gating, particularly at Seff=80%.
• No significant differences in image quality or velocities were observed between 1.5T and 3T.

Conclusions:

• The new navigator scheme is feasible for 4D flow MRI.
• It enables predictable scan times while preserving image quality and velocity data.
• This approach may enhance clinical applicability of 4D flow MRI.