Use of an enhanced gradient system for diffusion MR imaging with motion-artifact reduction.
OBJECTIVE
A spin-echo diffusion-sensitized pulse sequence using high gradients (23 mT/m) is introduced.


METHODS
In order to minimize motion artefacts, velocity-compensating gradients, ECG-triggering and post-processing with phase correction and raw data averaging using navigator echoes was performed. The in vitro ratio of diffusion coefficients for water and acetone was determined and the water self-diffusion coefficient at different temperatures was evaluated. The pulse sequence was tested in 7 healthy volunteers and in 2 tumour patients with astrocytomas of grades I-II and III-IV. Both single-slice and multi-slice techniques were used.


RESULTS
The incorporation of phase correction clearly improved the quality of both diffusion-encoded images and the calculated diffusion maps. Mean values of the diffusion coefficients in vivo were for CSF 2.66 x 10(-9) m2/s and for white and grey matter 0.69 x 10(-9) m2/s and 0.87 x 10(-9) m2/s, respectively.


CONCLUSIONS
Velocity-compensating gradients in combination with a high gradient strength were shown to be useful for in vivo diffusion MR imaging.
Brockstedt
S
S
Department of Radiation Physics, University Hospital, Lund, Sweden.
Thomsen
C
C
Wirestam
R
R
De Poorter
J
J
De Wagter
C
C
Salford
L G
LG
Holtås
S
S
Ståhlberg
F
F
D000328:Adult; D016477:Artifacts; D001254:Astrocytoma / Q000175:diagnosis; D001921:Brain / Q000033:anatomy & histology; D001932:Brain Neoplasms / Q000175:diagnosis; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009068:Movement; D019047:Phantoms, Imaging