Pathological causes
In some instances the presence of abnormal compounds within the CSF is directly responsible for failure of fluid attenuation. Examples include:
- subarachnoid hemorrhage
- fat-containing lesions in subarachnoid space
- lipoma
- ruptured dermoid cyst
- melanin-containing lesions in the subarachnoid space
- meningeal melanomatosis
- meningeal melanocytosis
Increased leptomeningeal vascular permeability leads to accumulation of various compounds within CSF. Examples include:
- meningitis
- leptomeningeal metastasis (e.g. carcinomatosis, lymphomatosis)
- hyperintense acute reperfusion marker (HARM)
- inflammatory cerebral amyloid angiopathy
- migraine
Slow flow in sulcal vessels will cause high T2 signal also on non fluid-attenuated T2 weighted sequences, however this is not visible unless CSF signal is attenuated. Examples include:
Artifactual causes
- hyperoxygenation therapy
- related to the paramagnetic effects of oxygen on the magnetic field
- recent gadolinium contrast medium administration
- lasting ~2-24 hours, especially if there is adjacent pathology which involves disruption of the blood-brain barrier, or neovascularization 7
- CSF flow artifact
- vascular pulsation artifact
- magnetic susceptibility artifact
- motion artifact