"Sulcal FLAIR hyperintensity, can be encountered in a wide variety of conditions both pathological and artifactual. It can be due to changes in the content of CSF (e.g. meningitis and subarachnoid haemorrhage), slow-flow in leptomeningeal vessels (e.g. moyamoya and stroke), increased permeability of pial vessels (e.g. meningoencephalitis and leptomeningeal carcinomatosis) or artefacts (e.g. hyperoxygenation therapy and magnetic susceptibility artifact). These processes may co-exist. In cases where increased permeability is present, this finding can be accentuated or made visible by performing FLAIR after the administration of intravenous gadolinium-containing contrast agents."
"A variety of terms have been used to describe the presence of high T2 signal within the subarachnoid spaces on FLAIR. When contrast has been administered prior to performing FLAIR, the term CSF enhancement is often used 10. Strictly speaking, this is a different phenomenon from what we understand enhancement to be on post-contrast T1-weighted images, when the presence of gadolinium results in T1 shortening and abnormal increase in signal. On post-contrast FLAIR, the result is not an abnormal increase in signal, but rather a failure of normal FLAIR suppression to occur because of the paramagnetic effects of small concentrations of gadolinium 10."
Expected headings
"Pathological causes"
"Artifactual causes"
"Sulcal FLAIR hyperintensity, can be encountered in a wide variety of conditions both pathological and artifactual. It can be due to changes in the content of CSF (e.g. meningitis and subarachnoid haemorrhage), slow-flow in leptomeningeal vessels (e.g. moyamoya and stroke), increased permeability of pial vessels (e.g. meningoencephalitis and leptomeningeal carcinomatosis) or artefacts (e.g. hyperoxygenation therapy and magnetic susceptibility artifact). These processes may co-exist. In cases where increased permeability is present, this finding can be accentuated or made visible by performing FLAIR after the administration of intravenous gadolinium-containing contrast agents."
"FLAIR is a T2-weighted sequence with a long inversion recovery pulse timed so as to attenuate the signal from CSF. This timing relies on CSF being free of any compounds or influences that change its relaxation time. Even small amounts of protein, blood, gadolinium or distortion of the magnetic field by foreign bodies can cause the timing to be altered and for the fluid attenuation not to take place."
"leptomeningeal metastasis (e.g. carcinomatosis, lymphomatosis)"