Add MRI Examples

[chaithyagr]

No description provided.

[coveralls]

Pull Request Test Coverage Report for Build 291

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 65.052%

---

Totals
Change from base Build 289:	0.0%
Covered Lines:	2524
Relevant Lines:	3880

---

💛 - Coveralls

[sfarrens]

@chaithyagr Have you tested the non_cartesian_reconstruction.py example using Python 3.7? I could only make pynfft work with Python 3.6.

[chaithyagr]

@chaithyagr Have you tested the non_cartesian_reconstruction.py example using Python 3.7? I could only make pynfft work with Python 3.6.

I am not sure, let me do that once. If I remember right, we need to use pynfft from github: pip install git+https://github.com/ghisvail/pyNFFT.git
Can you please let me know that you still are facing issues with it?

[sfarrens]

I didn't save the output, but the latest PyPi version of pynfft did not compile with Python 3.7. Some Cython issue if I remember correctly.

[chaithyagr]

I think I faced same issue, the latest PyPi version is not good with some version of pythons and thus we rely on the github version. We could request a new release if needed from ghisvail

[sfarrens]

For the moment, I think we should just include a check in the example to see if pynfft is installed, if not raise a warning and exit normally.

[philouc]

Note that Jyh-Miin Lin will arrive at CEA Grenoble in Oct 21. This should ease the interactions. Once he joins us, I will invite him to slack and open pysap access for him as contributor if everyone agrees on that?

[chaithyagr]

@philouc note that this is pynfft and not pyNUFFT, we have ongoing PR for best working with pyNUFFT, and surely we will have a round of discussion on that. But for now, we are using NFFT which is developed by Ghishval and which is just a wrapper to nfft3 C library.

[chaithyagr]

For the moment, I think we should just include a check in the example to see if pynfft is installed, if not raise a warning and exit normally.

This is exactly what we do in pysap-mri :
https://github.com/CEA-COSMIC/pysap-mri/blob/master/mri/reconstruct/fourier.py#L23-L28