Hi Chris,

Thanks for your pointers. I upgraded to the newest dcm2niix version and changed the command, but got the same error that the package is unable to detect any images. However, it seemed to locate the PAR files after uncompressing them (filename.PAR.gz > filename.PAR). 
However, it now returns a different error related to the number of slices:

path/to/new_version/dcm2niix -o /$outdir /$imgdir/filename.PAR

Compression will be faster with 'pigz' installed
Chris Rorden's dcm2niiX version v1.0.20181125 GCC4.8.2 (64-bit Linux)
Warning: dcm2niix PAR is not actively supported (hint: use dicm2nii)
Found 18950 slices, but expected divisible by 18962: slices*grad*bval*cardiac*echo*dynamic*mix*labels = 38*1*1*1*1*499*1*1
/$imgdir
Error: Total number of slices (18950) not divisible by slices per 3D volume (38) [acquisition aborted]. Try dicm2nii or R2AGUI: 
/$imgdir


It also reported an error related to the number of dynamics, which was inconsistent with the header info. This warning disappeared after manually changing the header (PAR file). 

Can you give any advise on how to deal with the error above?
Thanks!

Best,
Josephine