Error extracting specific b-value shells in non-HARDI sequence

Hi,

I was handed an acquisition with the gradient directions listed at the bottom of the post. Most operations on the data result in a [ERROR] DWI volumes could not be classified into b-value shells; gradient encoding may not represent a HARDI sequence error, I thought I’d try extracting the b=1000 “shell”, but get this error:

dwiextract -force -shell 1000 dti.mif dti-b1000.mif
dwiextract: [WARNING] existing output files will be overwritten
dwiextract: [ERROR] DWI volumes could not be classified into b-value shells; gradient encoding may not represent a HARDI sequence

any suggestions on how I might extract something useful from the data?

-dan

b-values

mrinfo dti.mif -dwgrad
           0            0            0            0
 0.000171634    -0.999568   -0.0293747          200
   -0.012155  -0.00602182    -0.999908          150
   -0.999528    -0.018454   -0.0245807          150
    0.700613    -0.713288   -0.0190032          350
    0.708191  -0.00864206    -0.705969          350
 -0.00419509    -0.714502    -0.699621          350
 -0.00419509     0.714502    -0.699621          350
   -0.700613    -0.713288   -0.0190032          350
   -0.708191  -0.00864206    -0.705969          350
    0.575013    -0.585446    -0.571501          500
    0.575013     0.585446    -0.571501          500
   -0.575013    -0.585446    -0.571501          500
   -0.575013     0.585446    -0.571501          500
 1.99504e-05     -0.99991   -0.0134092          700
 -0.00302786  -0.00454752    -0.999985          650
   -0.999885  -0.00911076   -0.0121446          650
    0.891333    -0.453207   -0.0113085          850
    0.895496  -0.00706024    -0.445014          850
    0.443969    -0.895965    -0.011768          850
    0.446344  -0.00489115    -0.894848          850
  -0.0010585      -0.8972    -0.441622          850
 -0.00215196    -0.452824    -0.891597          850
 -0.00215196     0.452824    -0.891597          850
  -0.0010585       0.8972    -0.441622          850
   -0.443969    -0.895965    -0.011768          850
   -0.446344  -0.00489115    -0.894848          850
   -0.891333    -0.453207   -0.0113085          850
   -0.895496  -0.00706024    -0.445014          850
    0.406737    -0.414139    -0.814281         1000
    0.406737     0.414139    -0.814281         1000
   -0.406737    -0.414139    -0.814281         1000
   -0.406737     0.414139    -0.814281         1000
    0.815247    -0.414195    -0.404741         1000
    0.815247     0.414195    -0.404741         1000
    0.406132    -0.820023    -0.403261         1000
    0.406132     0.820023    -0.403261         1000
   -0.406132    -0.820023    -0.403261         1000
   -0.406132     0.820023    -0.403261         1000
   -0.815247    -0.414195    -0.404741         1000
   -0.815247     0.414195    -0.404741         1000
    0.704154     -0.70999  -0.00902211         1350
    0.707641  -0.00482968    -0.706556         1300
 -0.00105847    -0.710558    -0.703638         1350
 -0.00105847     0.710558    -0.703638         1350
   -0.704154     -0.70999  -0.00902211         1350
   -0.707641  -0.00482968    -0.706556         1300
    0.664876    -0.670223    -0.329759         1500
    0.666062    -0.338407    -0.664712         1500
    0.666062     0.338407    -0.664712         1500
    0.664876     0.670223    -0.329759         1500
    0.331795    -0.670502     -0.66358         1500
    0.331795     0.670502     -0.66358         1500
-0.000658634    -0.999962  -0.00864213         1500
 -0.00201742  -0.00403885     -0.99999         1500
   -0.331795    -0.670502     -0.66358         1500
   -0.331795     0.670502     -0.66358         1500
   -0.664876    -0.670223    -0.329759         1500
   -0.666062    -0.338407    -0.664712         1500
   -0.666062     0.338407    -0.664712         1500
   -0.664876     0.670223    -0.329759         1500
   -0.999953  -0.00538644  -0.00807604         1500