Parallel imaging#
Parallel imaging recovers an image from k-space undersampled along the phase-encoding directions by exploiting the spatial sensitivities of a receive array. A SENSE reconstruction is only as accurate as its coil sensitivity maps, and it propagates the thermal noise of the channels, amplified by the g-factor. This section treats both: sensitivity estimation from the autocalibration (ACS) region, by direct division and by ESPIRiT; joint estimation of image and sensitivities by nonlinear inversion when the ACS region is too small for a separate calibration; and prewhitening of correlated channel noise, evaluated by the SNR of the reconstruction. The MRI encoding operator derives the SENSE model and Nonlinear forward models the joint estimation.
