A quantitative method for fast diffusion imaging using magnetization-prepared TurboFLASH.
For the in vivo measurement of the apparent diffusion coefficient (ADC), it is desirable for the total imaging time to be as short as possible. One technique is based on a TurboFLASH acquisition in which the diffusion gradients are inserted into a driven equilibrium Fourier transform (DEFT) combination of hard pulses. However, this sequence has the disadvantage that eddy current-induced inhomogeneities lead to incomplete refocusing of the magnetization during the diffusion preparation and to incorrect ADC values. A modification to the sequence is suggested that eliminates this error by phase-cycling the second 90 degrees pulse of the preparation. This study also investigates the effect of a reduced delay time between acquisitions on the accuracy of the measurement. The quality of the TurboFLASH sequence is demonstrated by experimental validation on an agar phantom and in vivo on the rat brain using a high-field (8.5 T) system. Reduction of the interexperiment delay time is shown to be achievable to a certain degree without compromising the measurement accuracy.
Thomas
D L
DL
Royal College of Surgeons Unit of Biophysics, Institute of Child Health, University College London Medical School, UK.
Pell
G S
GS
Lythgoe
M F
MF
Gadian
D G
DG
Ordidge
R J
RJ
D000818:Animals; D016477:Artifacts; D001834:Body Water / Q000378:metabolism*; D001921:Brain / Q000033:anatomy & histology*; D004058:Diffusion; D017352:Echo-Planar Imaging / Q000295:instrumentation; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D019047:Phantoms, Imaging; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values