CONTRAST OPTIMIZATION OF FLUID-ATTENUATED INVERSION-RECOVERY (FLAIR) IMAGING

The optimization of contrast is considered for the fluid-attenuated in version recovery (FLAIR) MRI pulse sequence, specifically the contrast of multiple sclerosis (MS) to white matter (WM), A performance bound is identified at 1.5 Tesla as that provided using an inversion time (T I) of 2900 ms, It is shown that TR/TI times exceeding 11000/2600 ms pr ovide about 90% of the MS-WM contrast possible theoretically, The comm only reported TR/TI combination of 6000/2000 provides only about 60%, For TR times exceeding 8000 ms, an echo time (TE) of 140 ms is at or n ear optimum. Use of TR/TI times less than 9000/2400 lacks efficiency i n multisection imaging. Predicted relative contrast performance of TR/ TI 11000/2600 versus 6000/2000 was evaluated in seven patients with kn own MS lesions, and measurements closely matched theoretical predictio ns. It is strongly recommended that for near optimum contrast and high multisection efficiency, FLAIR should be performed with TR/TI times e xceeding 10000/2500 ms.