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

ABSTRACT

PURPOSE: In this work, we explore the use of multiband (MB) balanced steady-state free precession (bSSFP) with blipped-controlled aliasing in parallel imaging (CAIPI), which avoids the issues of altered frequency response associated with RF phase cycling, and show its application to accelerating cardiac cine imaging. METHODS: Blipped and RF-cycled CAIPI were implemented into a retrospective-gated segmented cine multiband bSSFP sequence. The 2 methods were compared at 3T using MB2 to demonstrate the effect on frequency response. Further data (4 subjects) were acquired at both 1.5T and 3T collecting 12-slice short axis stacks using blipped-CAIPI with MB acceleration factors of 1-4. The impact on SNR and contrast was evaluated along with g-factors at different accelerations. RESULTS: Data acquired with blipped-CAIPI multiband bSSFP up to factor 4 yielded functional cine data with good SNR and contrast, while reliably keeping dark-band artefacts clear of the heart at 1.5T. SAR limits the maximum MB acceleration, particularly at 3T, where minimum TR increase is problematic and leakage artefacts are more prevalent. Mean g-factors across the heart were measured at 1.00, 1.06, and 1.12 for MB2-MB4, whereas blood-pool SNR measures (end-diastole) decreased by 11.8, 21.5, and 36.9%; ultimately LV-myocardium CNR remained sufficient at 1.5T with values ranging 15.6, 13.4, 11.9, and 9.6 (MB1-MB4). CONCLUSION: Blipped-CAIPI multiband bSSFP can be used in cardiovascular applications without affecting the frequency response because of controlled aliasing and can be readily incorporated into segmented cine acquisitions without adding any additional constraints because of phase cycling requirements. The method was used to collect full ventricular coverage within a single breath-hold.