Evaluation of slice accelerations using multiband echo planar imaging at 3 T.

Area of Science:

• Magnetic Resonance Imaging
• Neuroimaging
• Biophysics

Background:

• Slice accelerated multiband (MB) echo planar imaging (EPI) is crucial for improving fMRI temporal resolution.
• Evaluating residual aliasing and signal leakage is essential for optimizing MB EPI performance.
• High acceleration factors are desirable for whole brain imaging but pose challenges for image quality.

Purpose of the Study:

• To evaluate residual aliasing in slice accelerated MB EPI at 3 T without in-plane accelerations.
• To introduce and utilize a novel leakage (L-) factor for quantifying signal leakage between simultaneously acquired slices.
• To determine the maximum achievable slice acceleration factors for routine whole brain imaging with acceptable quality.

Main Methods:

• Simultaneously excited and acquired slices in MB EPI were analyzed.
• No in-plane accelerations were employed to isolate the effects of slice acceleration.
• A novel leakage (L-) factor was developed and applied to quantify inter-slice signal leakage.
• Spectral analyses of single-shot fMRI time series were performed.

Main Results:

• Slice acceleration factors up to eight (MB=8) with blipped controlled aliasing in parallel imaging (CAIPI) demonstrated acceptable image quality and integrity for whole brain imaging at 3 T.
• The proposed leakage (L-) factor effectively quantified signal leakage between simultaneously acquired slices.
• Temporal fluctuations in fMRI time series remained distinguishable and comparable up to slice acceleration factors of nine (MB=9).

Conclusions:

• Slice accelerated MB EPI, particularly up to MB=8 with blipped CAIPI, is suitable for routine whole brain imaging at 3 T.
• The developed L-factor provides a valuable metric for assessing image quality in accelerated EPI.
• Increased temporal efficiency from higher MB factors enables advanced neuroimaging techniques and improved data acquisition strategies.