Comparison of Fast FLAIR and Echo-Planar FLAIR Imaging in Cere b ral Lesions

ABSTRACT

PURPOSE: To evaluate the usefulness of echo-planar FLAIR imaging in various cerebral lesions as compared with fast FLAIR imaging. MATERIALS AND METHODS: We obtained consecutive fast FLAIR and echo-planar FLAIR images in 33patients in whom MR imaging had revealed ischemic infarction (n=11), acute infarction (n=5), brain tumor (n=3), other conditions (n=3) or no abnormality (n=11). On both sets of images, percentage contrast and contrast to noise ratio (CNR) were calculated for white matter-gray matter and white matter-lesion. RESILTS White matter-gray matter percentage contrast and CNR were lower on echo-planar FLAIR imaging than on fast FLAIR imaging (percentage contrast, 19 +/- 2 % vs 28 +/- 3 %, CNR, 2.77 +/- 0. 5 vs 4.86 +/- 0.7). White matter-lesion percentage contrast on echo-planar FLAIR imaging was similar to or greater than that on fast FLAIR imaging; 75 +/- 12 % vs 45 +/- 11 % in ischemic infarction, 80 +/- 12 % vs 78 +/- 11% in acute infarction, and 121 +/- 25 % vs 102 +/- 15 % for tumors. White matter-lesion CNR was similar on both sets of images 8.3 +/- 0.9 vs 7.9 +/- 0.8 in ischemic infarction, 11 +/- 1.5 vs 9.5 +/- 1.2 in acute infarction, and 24 +/- 4 vs 27 +/- 3 for tumors. Due to high susceptibility to magnetization, echo-planar FLAIR imaging showed image degradation at the interface of the paranasal sinus and adjacent to the temporal bone. CONCLUSION: Echo-planar FLAIR imaging may be a useful pulse sequence in the diagnosis of various cerebral lesions.