Simultaneous multislice imaging of the heart using multiband balanced SSFP with blipped-CAIPI

Area of Science:

• Magnetic Resonance Imaging
• Cardiovascular Imaging
• Parallel Imaging

Background:

• Balanced steady-state free precession (bSSFP) is a common MRI sequence for cardiac cine imaging.
• Multiband (MB) acceleration and controlled aliasing in parallel imaging (CAIPI) are techniques used to reduce scan times.
• Traditional CAIPI methods using RF phase cycling can alter the frequency response of bSSFP sequences.

Purpose of the Study:

• To evaluate the application of multiband (MB) balanced steady-state free precession (bSSFP) with blipped-controlled aliasing in parallel imaging (CAIPI) for accelerating cardiac cine imaging.
• To assess whether blipped-CAIPI avoids the frequency response alterations associated with RF phase cycling in bSSFP.
• To determine the feasibility of incorporating this technique into segmented cine acquisitions.

Main Methods:

• Implemented blipped-CAIPI and RF-cycled CAIPI into a retrospective-gated segmented cine MB bSSFP sequence.
• Compared the two CAIPI methods at 3T with MB2 acceleration to assess frequency response.
• Acquired 12-slice short-axis cardiac data at 1.5T and 3T using blipped-CAIPI with MB acceleration factors from 1 to 4.

Main Results:

• Blipped-CAIPI MB bSSFP up to factor 4 yielded functional cine data with good SNR and contrast, keeping dark-band artifacts clear of the heart at 1.5T.
• Mean g-factors were low (1.00-1.12 for MB2-MB4), and LV-myocardium contrast-to-noise ratio (CNR) remained sufficient at 1.5T.
• Specific absorption rate (SAR) limits maximum MB acceleration, especially at 3T, where TR increases and leakage artifacts are more prevalent.

Conclusions:

• Blipped-CAIPI MB bSSFP is suitable for cardiovascular applications, avoiding frequency response issues and phase cycling constraints.
• This method enables efficient cardiac cine imaging, allowing for full ventricular coverage within a single breath-hold.
• The technique can be readily integrated into existing segmented cine acquisition protocols.