Retrospective motion gating in cardiac MRI using a simultaneously acquired navigator

Area of Science:

• Cardiovascular Imaging
• Magnetic Resonance Imaging
• Medical Physics

Background:

• Cardiac magnetic resonance imaging (CMRI) traditionally relies on electrocardiogram (ECG) gating and breath-holding for diagnostic image quality.
• These requirements can limit patient comfort and applicability, particularly for patients unable to comply with breath-holding instructions.
• Alternative self-gating techniques exist but may not always achieve optimal image quality or efficiency.

Purpose of the Study:

• To introduce and evaluate a novel simultaneous acquisition technique (SIMNAV) for CMRI.
• To assess the feasibility of acquiring both image and navigator signals concurrently.
• To compare the performance of SIMNAV with existing gating methods in terms of image quality and efficiency.

Main Methods:

• A modified balanced steady-state free precession (bSSFP) pulse sequence was developed to simultaneously acquire image and navigator signals.
• A supplementary radiofrequency (RF) pulse was added to excite a navigator slice.
• Alternating RF pulse phases facilitated the separation of image and navigator data.
• Navigator signals were compared against conventional ECG gating and self-gating techniques in seven healthy subjects.

Main Results:

• The SIMNAV technique successfully acquired simultaneous image and navigator signals in vivo.
• Cardiac cine images obtained with SIMNAV demonstrated sufficient image quality, comparable to ECG-gated, breath-held acquisitions.
• Navigator signals from SIMNAV showed comparable performance to current gating devices and self-gating methods.

Conclusions:

• SIMNAV offers a viable alternative for CMRI, eliminating the need for ECG devices and breath-holding.
• The technique maintains feasible imaging time efficiency while ensuring diagnostic image quality.
• SIMNAV has the potential to enhance CMRI accessibility and patient experience.