Post-contrast FLAIR MR imaging of the brain in children: normal and abnormal intracranial enhancement

Objective. To describe the normally enhancing intracranial structures on fluid-attenuated inversion recovery (FLAIR) MRI and evaluate the usefulness of postcontrast FLAIR images of the brain in the assessment of enhancing lesions by comparing postcontrast FLAIR imaging with postcontrast T1-weighted (T1-W) imaging in children. Materials and methods. In 218 children, 249 pre- and postcontrast FLAIR MRI examinations of the brain were obtained consecutively between August 2001 and April 2002. The normally enhancing intracranial structures on FLAIR imaging were assessed in 77 MRI studies of 74 children who showed normal intracranial imaging findings. In 86 MRI studies in 68 children who showed enhancing intracranial lesions, lesion conspicuity on postcontrast FLAIR imaging was compared with that on postcontrast T1-W imaging for all lesions (n=107), intra-axial lesions (n=40), or extra-axial lesions (n=67). Results. The normally enhancing intracranial structures on FLAIR MRI were the choroid plexus (99%, 76/77), pituitary stalk (84%, 65/77), pineal gland (71%, 55/77), dural sinuses (26%, 20/77), and cortical veins (9%, 7/77). Of all the enhancing lesions, lesion conspicuousness on postcontrast FLAIR imaging was better than postcontrast T1-weighted imaging in 42, equal in 28, and worse in 37. Of 40 intra-axial lesions, lesion conspicuousness on postcontrast FLAIR imaging was better in 6, equal in 10, and worse in 24. Of 67 extra-axial lesions, lesion conspicuity on postcontrast FLAIR imaging was better in 36, equal in 18, and worse in 13. Conspicuousness of extra-axial lesions was significantly better than that of intra-axial lesions on postcontrast FLAIR imaging (P<0.001). Conclusions. The choroid plexus, pituitary stalk, pineal gland, dural sinuses, and cortical veins show normal enhancement on postcontrast FLAIR MRI in children, and postcontrast FLAIR imaging appears better than postcontrast T1-W imaging in the assessment of extra-axial enhancing lesions in children.