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 possib le. One technique is based on a TurboFLASH acquisition in which the di ffusion gradients are inserted into a driven equilibrium Fourier trans form (DEFT) combination of hard pulses. However, this sequence has the disadvantage that eddy current-induced inhomogeneities lead to incomp lete refocusing of the magnetization during the diffusion preparation and to incorrect ADC values. A modification to the sequence is suggest ed that eliminates this error by phase-cycling the second 90 degrees p ulse of the preparation. This study also investigates the effect of a reduced delay time between acquisitions on the accuracy of the measure ment. The quality of the TurboFLASH sequence is demonstrated by experi mental validation on an agar phantom and in vivo on the rat brain usin g a high-field (8.5 T) system. Reduction of the interexperiment delay time is shown to be achievable to a certain degree without compromisin g the measurement accuracy.