FLAIR*: A Combined MR Contrast Technique for Visualizing White Matter Lesions and Parenchymal Veins

Abstract

Purpose:To evaluate a magnetic resonance (MR) imaging contrast technique, called FLAIR*, that combines the advantages of T2-weighted fluid-attenuated inversion recovery (FLAIR) contrast and T2*-weighted contrast on a single image for assessment of white matter (WM) diseases such as multiple sclerosis (MS). Materials and Methods:This prospective pilot study was HIPAA compliant and institutional review board approved. Ten patients with clinically definite MS (eight men, two women; mean age, 41 years) provided informed consent and underwent 3.0-T MR imaging. Images from a T2-weighted FLAIR sequence were combined with images from a T2*-weighted segmented echo-planar imaging sequence performed during contrast material injection, yielding high-isotropic-resolution (0.55 3 0.55 3 0.55 mm 3 ) FLAIR* images. Qualitative assessment was performed for image quality, lesion conspicuity, and vein conspicuity. Contrast-to-noise ratio (CNR) was calculated to compare normal-appearing WM (NAWM) with cerebrospinal fluid, lesions, and veins. To evaluate the differences in CNR among imaging modalities, a bootstrap procedure clustered on subjects was used, together with paired t tests. Results:High-quality FLAIR* images of the brain were produced at 3.0 T, yielding conspicuous lesions and veins. Lesion-to-NAWM and NAWM-to-vein CNR values were significantly higher for FLAIR* images than for T2-weighted FLAIR images (P , .0001). Findings on FLAIR* images included intralesional veins for lesions located throughout the brain and a hypointense rim around some WM lesions. Conclusion:High-isotropic-resolution FLAIR* images obtained at 3.0 T yield high contrast for WM lesions and parenchymal veins, making it well suited to investigate the relationship between WM abnormalities and veins in a clinical setting.q RSNA, 2012

“Central vessel sign” on 3T FLAIR* MRI for the differentiation of multiple sclerosis from migraine

“…Our study is one of only several that have demonstrated the feasibility of detection of CVS on 3T MRI in MS,19, 20, 30, 31 and only a few studies have investigated whether the CVS distinguishes MS from other populations at 3T 16, 18. Lummel et al 16.…”

“…There remains a need to develop consensus criteria for imaging methodology for further study of the CVS in MS. We propose further investigation on 3T MRI using methods employed in this study, as FLAIR* may be more sensitive than prior approaches due to its ability to produce high‐resolution, isotropic voxels with adequate T2* weighting, its use of a multichannel coil, and the addition of a gadolinium‐based contrast agent to enhance the susceptibility contrast within veins 20, 32, 33. Although use of a 32‐channel coil may have yielded better images in this study, prior studies using FLAIR* have been performed with standard SENSE‐8 head coils that are widely used at imaging centers 20, 32…”

“…Although use of a 32‐channel coil may have yielded better images in this study, prior studies using FLAIR* have been performed with standard SENSE‐8 head coils that are widely used at imaging centers 20, 32…”

“…It has been known from histopathological studies at autopsy that most MS lesions are centered around veins,11 and only recently have a variety of imaging techniques using susceptibility‐weighted imaging on ultrahigh‐field 7‐tesla (T) research magnets demonstrated this relationship in vivo 12, 13, 14, 15, 16, 17. A small number of studies have also evaluated the ability of 3T scanners, which are used routinely in clinical practice, to detect a “central vessel” (CV) in MS lesions 18, 19, 20, 21. These studies have used a variety of methods to image vessels and have included small numbers of participants, yet several suggest that detection of CVS may discriminate MS from alternative diagnoses on 3T 18, 22, 23, 24.…”

Central vein sign differentiates Multiple Sclerosis from central nervous system inflammatory vasculopathies

“…Data were collected as DICOM images and processed and visualized using Medical Image Processing, Analysis, and Visualization (MIPAV; NIH; http://mipav.cit.nih.gov). FLAIR* images were generated with the following steps26: (1) coregistration between T2‐FLAIR and T2* images, (2) upsampling of the T2‐FLAIR image to match the T2* resolution, and (3) voxelwise multiplication.…”