Hi

Wondering if anyone knows this. I'm trying to convert a set of dicoms(diffusion images) into niftis. However it gives me 4 files file.nii, xfile.nii, file.bvec, xfile.bval. Does anyone know why it comes up with the x infront of the filename? Also file.nii and xfile.nii are different sizes which puzzles me even more. file.nii is bigger than xfile.nii. Thank you for any help.

Kevin

I am going to guess that your data came from a Philips scanner, and you set it up to generate an ADC map for you. Unfortunately, Philips does not separate the computed ADC as a different series from the raw data (technically a violation of DICOM standard for derived data). The problem is that the ADC map is not suitable for processing, as it is neither a B0 image or a directional image. Further, there is no appropriate B-value or B-vec for a ADC map, and including the ADC map with the others would disrupt subsequent processing. Therefore, my software converts the raw data, and then creates a second dataset with the 'x' prefix that only includes the raw images and the associated B-vec and B-value files. You can now process these - after motions correction, eddy current correction and topup you can run dtifit and you will get a much better ADC map than your scanners' simple estimate. 

If I were you, I would set up the scanner not to create these maps, as they are redundant and not cleaned up. However, my software is robust to the presence of these inappropriate images. 

This also explains why the 'x' file is smaller - if you view it you will see that the ADC volume has been removed.

Chris

Thank you for your explanation. Yes we're our data are from a Phillips. Thank you for your help and brilliant software. 

Kevin