what is mean by cartesian MRI?

For Cartesian MRI, the acquired complex signal fills k-space matrix. Each k-space row can be modeled as an underlying true signal plus Gaussian noise:
xr (t) + ixi (t) = sr (t) + nr (t) + i[si (t) + ni (t)]
where x(t) is the observed k-space signal, s(t) is the true under-lying noiseless k-space signal, n(t) is the AGN, and subscripts r and i denote real and imaginary components, respectively.

""here how can we get real and imaginary before applying FFT??????????"

pls help me

Answer 1

[Walter Roberson]

If your signal is represented as a complex vector, then you can use real() and imag() to extract the real and imaginary components.