High SNR rapid T1-weighted MPRAGE using spiral imaging with long readouts and improved deblurring
Dinghui Wang, Ryan K. Robison, Zhiqiang Li, James G. Pipe
Purpose
The goal of this work is to present the implementation of 3D spiral high-resolution MPRAGE and to demonstrate that SNR and scan efficiency increase with the increment of readout time.
Theory
Simplified signal equations for MPRAGE indicate that the T1 contrast can be kept approximately the same by a simple relationship between the flip angle and the TR. Furthermore, if T1 contrast remains the same, image SNR depends on the square root of the product of the total scan time and the readout time.
Methods
MPRAGE spiral sequences were implemented with distributed spirals and spiral staircase on 3 Tesla scanners. Brain images of three volunteers were acquired with different readout times. Spiral images were processed with a joint water–fat separation and deblurring algorithm and compared to Cartesian images. Pure noise data sets were also acquired for SNR evaluation.
Results
Consistent T1 weighting can be achieved with various spiral readout lengths, and between spiral MPRAGE imaging and the traditional Cartesian MPRAGE imaging. Noise performance analysis demonstrates higher SNR efficiency of spiral MPRAGE imaging with matched T1 contrast compared to the Cartesian reference imaging.
Conclusion
Fast, high SNR MPRAGE imaging is feasible with long readout spiral trajectories.