See the following information (https://web.stanford.edu/group/vista/cgi-bin/wiki/index.php/MRTrix_examples#Convert_.tck_file_into_.pdb_file):

5. Convert .tck file into .pdb file

MrTrix produces .tck file for storing streamline information, which is not compatible with Quench or mrDiffusion.

In order to convert .tck file into .pdb file, please use mrtrix_tck2pdb.m

mrtrix_tck2pdb('S1_SDPROB_lmax8_500000.tck', 'S1_SDPROB_lmax8_500000.pdb')

.pdb format is compatible with Quench, mrDiffusion, AFQ and LiFE.

Thank you Alexander ! I try it 

Hi Fanny,

this is maybe a bit late, but you can also use these software to visualize tck:

https://github.com/scilus/fibernavigator

https://www.imeka.ca/mi-brain