Here is some simulated spiral sense data. The matlab variables are

imf - original full image (256x256)
s1,s2,s2, s4 - sensitivities (256x256)
im1,im2,im3,im4 - images with these sensitivities

The simulated spiral data use 21 spiral interleaves of 5120 samples/interleave. The central 1/4 FOV is oversampled by a factor of 2, so that if you only use every other interleave, the middle is still fully sampled. The reconstructed images are 128x128.

k - k-space trajectory (5120x21)
w - k-space weighting (512x21)
fd1,fd2,fd3,fd4 - data sets for im1,im2,im3,im4.

Using grid2w, you can get images of the phantom with

imshow(abs(ifft2c(grid2w(fd1,k,w,128))),[]);

and similarly for the other images.

For spiral sense,  you'll want to drop interleaves, and see if you can still do the reconstruction. The sensitivity maps will have twice the resolution you need, so you'll want to subsample them by a factor of 2.