The low sensitivity of fluid-attenuated inversion-recovery MR in the detection of multiple sclerosis of the spinal cord.

PURPOSE To confirm the expected superiority of fluid-attenuated inversion-recovery (FLAIR) over conventional fast spin-echo MR imaging in the detection of multiple sclerosis (MS) of the spinal cord. METHODS Fifteen subjects with known MS involving the spinal cord and brain were studied prospectively. The entire cord was imaged with a phased-array coil on a 1.5-T MR system. Sagittal T1-weighted and fast spin-echo proton density- and T2-weighted images were followed by fast FLAIR images. FLAIR parameters were varied to optimize lesion conspicuity with optimal inversion times (TIs) ranging from 2400 to 2600. Lesion conspicuity and detection were compared between the fast spin-echo and FLAIR images by three radiologists who reached agreement by consensus. RESULTS The FLAIR technique effectively suppressed cerebrospinal fluid (CSF) signal and reduced CSF pulsation and truncation artifacts in all cases. Shorter imaging parameters (repetition time of 4000 to 6000, TI of 1500 to 2000) uniformly decreased lesion conspicuity in all subjects. Of 11 cord lesions in five subjects imaged with the longer parameters (repetition time of 8000 to 11,000, TI of 2400 to 2600), three were not seen on FLAIR images, four were less conspicuous on FLAIR images, and four were seen equally or better on FLAIR images. CONCLUSION Although successful in suppressing CSF signal and reducing imaging artifacts, fast FLAIR imaging appears unreliable in the detection of MS lesions in the spinal cord.