Contrast-enhanced fluid-attenuated inversion-recovery (FLAIR) versus contrast-enhanced T1 MRI in the evaluation of intracranial tumors: A comparative study

Abstract

INTRODUCTION: At most institutions, the favored contrast MR sequence is T1-weighted imaging (T1WI). However, lesion enhancement is occasionally inconspicuous on T1WI.Objective: This study aims to evaluate the diagnostic value of contrast-enhanced FLAIR compared to contrast-enhanced T1WI for intracranial tumors and to offer data for further clinical judgment. METHODS: 88 consecutive cases of intracranial tumors referred for contrast-enhanced brain MRI were analyzed. FLAIR and T1 were used alternately in equal percentages as the first contrast-enhanced sequence to avoid delayed contrast-enhancement effects of the lesions. Six quantitative criteria were considered: lesion-to-white matter contrast ratio (CR) and contrast-to-noise ratio (CNR), lesion-to-gray matter CR and CNR, and lesion-to-cerebrospinal fluid CR and CNR. For qualitative evaluation, two experienced radiologists assessed lesion conspicuity on contrast-enhanced-T1WI and FLAIR sequences using the following three scales: 1, FLAIR superior; 2, sequences equal; 3, T1 superior. RESULTS: For quantitative measurement, the contrast enhanced-FLAIR lesion-to-white matter, lesion-to-cerebrospinal fluid CR, and CNR values were statistically superior to those of the contrast enhanced-T1 weighted images (p = 0.001 in all). However, lesion-to-gray matter CR and CNR were slightly higher on CE-FLAIR, but with no statistically significant difference (p = 0.159, 0.184, respectively). For qualitative evaluation, both radiologists assessed that contrast enhanced-FLAIR images were superior to contrast enhanced-T1 weighted images for the evaluation of lesion conspicuity, especially when it was performed as the second sequence. CONCLUSION: FLAIR sequence was superior or comparable to T1 sequence, especially when performed as a second post-contrast sequence. Using contrast enhanced-FLAIR as a routine MRI sequence will increase diagnostic confidence.