Arachnoid cyst MRI
|
Arachnoid cyst Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Arachnoid cyst MRI On the Web |
|
American Roentgen Ray Society Images of Arachnoid cyst MRI |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: José Eduardo Riceto Loyola Junior, M.D.[2]
Overview
Diagnosis is principally by MRI. Frequently, arachnoid cysts are incidental findings on MRI scans performed for other clinical reasons. In practice, diagnosis of symptomatic arachnoid cysts requires symptoms to be present, and many with the disorder never develop symptoms.
MRI
MRI can demonstrate the exact location, extent, and relationship of the cyst, as well as differentiate arachnoid from epidermoid cysts. CSF signal is seen within the well-defined cyst on all sequences. Epidermoids also may have a signal identical or very similar to that of arachnoid cyst on T1-weighted and T2-weighted images. To differentiate this from arachnoid cysts FLAIR as well as diffusion weighted sequences are used. On the FLAIR sequence, , an arachnoid cysts follow the CSF signal, so no signal seen, while there is a higher signal with FLAIR in epidermoid cysts. With DWI, diffusion is reduced within epidermoids, which then appear brighter than CSF, but for arachnoid cysts the signal intensity is low. In some instances though, arachnoid cysts may contain proteinaceous fluid or blood, and signal loss on DWIs may not be marked, which can cause diagnostic confusion. Plain radiographic findings are nonspecific and are not valuable offer in the diagnosis of arachnoid cysts, except for changes in skull contour due to large cysts. Large arachnoid cysts should be considered for serial scans because they may show progressive enlargement, and patients may become candidates for surgical consideration. Indications for surgical intervention include hydrocephalus and increased intracranial pressure. Surgery for asymptomatic cysts is controversial.
Differential Diagnosis
| Intraventricularly: | Colloid cysts |
| Intraparenchymally: | Parasitic infections, cystic metastases |
| Porencephalic cysts | |
| Craniopharyngiomas | |
| Holoprosencephalies | |
| Agenesis of corpus callosum | |
| Defect in the hemispheral cleavage | |
| Dandy-Walker complex (posterior fossa cysts) |
MRI Images
Patient #1: Left middle cranial fossa arachnoid cyst
-
Cor T2
-
Sag T1
-
Axial T1 FLAIR
-
Axial T2
Patient #2: CT and MR images demonstrate a hemorrhagic arachnoid cyst
-
CT
-
Sag T1
-
Ax T1
-
Ax FLAIR
-
Ax T2
-
Ax T1 with GAD
References
- ↑ Cincu, Rafael, Amit Agrawal, and Jose Eiras. "Intracranial arachnoid cysts: current concepts and treatment alternatives." Clinical neurology and neurosurgery 109.10 (2007): 837-843.