For PRC use only
Date of approval:
Signature of Chair:
Siemens Vision 1.5T Sequence Description
Sequence name: DTI v2.0, 2.1, 2.2, 2.3, and 2.4 – diffusion tensor imaging sequences
Developer: Jan Hrabe, NKI
Date: 5/4/2001
Filenames:
Location: /usr/appl/sequence/local
dti_v20.ekc dti_v21.ekc
dti_v22.ekc dti_v23.ekc
dti_v24.ekc
Other files: SPL source code file dti_v11.sph in the $EXT/local directory.
Brief description: These sequences are based on the approved DTI sequences dti_v14.ekc and
dti_v15.ekc, the main characteristics are as follows:
1. dti_v20.ekc: up to 27 slices with reduced slice thickness of up to 2.5 mm (uses longer ramp
times), acquisition matrix 96 x 128, TE 100ms, max gradient 20.9 mT/m, 6+1 b values (1000
s/mm2) in directions based on Jones DK, Horsfield MA, Simmons A: Optimal Strategies for
Measuring Diffusion in Anisotropic Systems by Magnetic Resonance Imaging (MRM
42:515-525, 1999), page 518. Slice profiles are identical to those in sequences dti_v1X.ekc.
2. dti_v21.ekc: identical to v20 except 8+1 b values are used and only 19 slices can be acquired.
3. dti_v22.ekc: intended for isotropic acquisition, minimum voxel size 2.5 mm, matrix 128 x
128, TE 100 ms, 6+1 b values, 27 slices, EPI BW increased to maximum possible (0.6 ms
per line), max. diffusion gradient 20.856 mT/m, b = 1000 s/mm2.
4. dti_v23.ekc: identical to dti_v22.ekc except 8+1 b values are used and only 20 slices can be
acquired.
5. dti_v24.ekc: DTI sequence with TE reduced to 82.92 ms to increase SNR. 27 (matrix 128 x
128) slices can be acquired with 2.5 mm cubic voxels but only in the principal orientations
(no oblique slices). 6+1 b values (1000 s/mm2) are acquired in directions that always
combine 2 gradients (as in the dti_v13.ekc). The directions are: (0,0,0), (1,1,0), (1,0,1),
(0,1,1), (1,-1,0), (-1,0,1), (0,1,-1) for (phase, read, slice).