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-tonoise 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.