Hi Anastasia,<div><br></div><div>my subjects have gradient=0 only in first or last line.<br><div><br></div><div>I'm noting that the subjects having 0.000 0.000 0.000 in the first line of bvecs.txt (0 in vals.txt) show correct tracts.</div><div><br></div><div>The subjects that&nbsp;having 0.000 0.000 0.000 as last line of&nbsp;bvecs.txt show wrong or lacking tracts.</div><div><br></div><div>For these subjects, I have already checked registration and gradients.</div><div><br></div><div>Is possible that this issue depends from&nbsp;setting of nb0.</div><div><br></div><div>In both cases (first or last line with 0.000) I have used set nb0 = 1. Is this correct?</div><div><br></div><div><br></div><div>Thank you very much,</div><div><br></div><div><br></div><div><br></div><div>Stefano</div><div>&nbsp;</div><div><br></div></div>