Reduced Scan Time 3D FLAIR Using Variable Repetition Time

Neville D. Gai¹, John Anthony Butman¹

3D FLAIR now provides high resolution images of the entire brain in a clinically reasonable scan time using extended modulated refocusing trains. However, the repetition time still includes a relatively long dead time to allow for magnetization recovery. Here, we describe a technique that reduces the scan time by varying the repetition time in a predetermined fashion using a Blackman-Harris window function. As a result, the effective TR of the sequence is still maintained which results in comparable SNR and CNR while reducing the total scan time. Simulation and measurements in volunteers confirm the utility of the technique.