Abnormal hyperintensity within the subarachnoid space evaluated by fluid-attenuated inversion-recovery MR imaging: a spectrum of central nervous system diseases

Abstract

A variety of central nervous system (CNS) diseases are associated with abnormal hyperintensity within the subarachnoid space (SAS) by fluid-attenuated inversion-recovery (FLAIR) MR imaging. Careful attention to the SAS can provide additional useful information that may not be available with conventional MR sequences. The purpose of this article is to provide a pictorial essay about CNS diseases and FLAIR images with abnormal hyperintensity within the SAS. We present several CNS diseases including subarachnoid hemorrhage, meningitis, leptomeningeal metastases, acute infarction, and severe arterial occlusive diseases such as moya-moya disease. We also review miscellaneous diseases or normal conditions that may exhibit cerebrospinal fluid hyperintensity on FLAIR images. Although the detection of abnormal hyperintensity suggests the underlying CNS diseases and narrows differential diagnoses, FLAIR imaging sometimes presents artifactual hyperintensity within the SAS that can cause the misinterpretation of normal SAS as pathologic conditions; therefore, radiologists should be familiar with such artifactual conditions as well as pathologic conditions shown as hyperintensity by FLAIR images. This knowledge is helpful in establishing the correct diagnosis.

Double Inversion Recovery MR Sequence for the Detection of Subacute Subarachnoid Hemorrhage

“…8,26 However, SAH can still be misdiagnosed by using FLAIR imaging due to the time interval between symptom onset and brain imaging 12 or image artifacts. 13,14 T2* is considered useful for the diagnosis of subacute or chronic SAH. 6,16 This sequence appears effective in detecting a prior SAH indicating the location of a ruptured aneurysm.…”

“…11 Nevertheless, SAH can still be misdiagnosed by using FLAIR imaging due to the time interval after onset 12 or artifacts. 13,14 T2* gradient-echo sequences are useful for subacute or chronic SAH depiction. 6,15,16 Susceptibility-weighted imaging uses tissue magnetic-susceptibility differences to generate a unique contrast, based on a 3D flow-compensated gradient-echo sequence.…”

Prompt Contrast Enhancement of Cerebrospinal Fluid Space in the Fundus of the Internal Auditory Canal: Observations in Patients with Meningeal Diseases on 3D-FLAIR Images at 3 Tesla

“…[3][4][5][6][7][8] Compared to 2D-FLAIR, a 3D-FLAIR sequence using a nonselective inversion pulse allows thinner slices while avoiding cerebrospinal ‰uid (CSF) motion artifacts. 9,10 FLAIR is sensitive to abnormalities in the subarachnoid space 3 and is able to detect subtle contrast enhancement in CSF space after intravenous administration of Gd-DTPA under various disease conditions. [11][12][13] Contrast enhancement has been observed on 3D-FLAIR images at 3T in the basal turn of the cochlea 4 hours after intravenous Gd-DTPA administration in healthy subjects.…”

Hemorragia subaracnoidea aneurismática: guía de tratamiento del Grupo de Patología Vascular de la Sociedad Española de Neurocirugía

“…Dado que la sensibilidad de la TC no es absoluta, la PL debe realizarse cuando existen dudas de la presencia de sangre en la TC inicial (TC normal o retraso en la referencia a un centro hospitalario). La resonancia magnética (RM) ha sido utilizada también en el diagnóstico de sospecha de HSA, fundamentalmente con la aplicación de imágenes FLAIR (fluid attenuated inversion recovery) 15,59,136 . También se ha usado en el diagnóstico de la causa del sangrado pero esta técnica ha sido superada por la mayor disponibilidad y rapidez por el TC helicoidal o angio TC.…”