E.GAMY-J.MAHLAOUI-T.AMIL-S-CHAOUIR-A.HANINE- M.MAHI-S.AKJOUJ Medical imaging military hospital Mohammed V instruction –Rabat. NR3
Intracranial arachnoid cysts are defined as a pocket full of intra-subarachnoid CSF without communication with the ventricular system. The aim of this study is to clarify the contribution of computed tomography (CT) and especially MRI. In the diagnosis with emphasis on information brought by the sequences (diffusion) in the differential diagnosis.
CT scans performed in axial and coronal. MRI includes the following morphological sequences weighted in T1, T2, FLAIR, and T2 * sequences RELEASE in the different planes.
CT shows a process of expansive cystic lesion that is hypodense and the same signal as cerebrospinal fluid (CSF), which can result in thinning of the cortex next, there is no contrast enhancement. MRI it has a signal identical to that of (LCS) on the sequences T1 and T2 without contrast. However to make a difference with an epidermoid cyst, FLAIR- weighted sequences, distribution and CISS are a great contribution.
CT: CSF density bone remodeling, no contrast enhancement.
MRI: T1/T2: iso intense to CSF
DWI: no signal no contrast enhancement
There is no causal link between the temporal lobe hypoplasia and arachnoid cysts appear despite their association. Hypothesis probable abnormalities of embryogenesis that affects Independently, and the formation of the arachnoid, and the temporal lobe in some patients, is the effect of compression KA. The search for evidence in favor of either MRI or hypogénésie compression of the temporal lobe by a KA.
In The hypoplasia of the temporal lobe, temporal lobe concave next to the KA, Discharge of the temporal horn and / or adjacent structures; sinuosity, ripple temporal cortex next to the KA. Decrease in the volume of adjacent parenchyma. Not discharge. No thinning of cortical bone next to the KA.
Epidermoid cyst: Irregular edge in, is insunie in tanks, Includes vessels and nerves Registered in 45% of cases at the basal cisterns. Light Flair hyperintense signal and Hyper Distribution. Light Flair hyperintense signal and Hyper Distribution
The chronic subdural hematoma: Lenticular, higher signal to CSF Subdural hygroma CAVITY porencephalic MEGAGRANDE TANK MALIGNANT CYSTIC NEURO-CYSTS ENTERIC CYST NEUROGLIAL
KA asymptomatic abstention KA giant symptomatic or asymptomatic high risk of bleeding: - Craniotomy + resection of the outer mb
The MRI allows the diagnosis of intracranial arachnoid cysts with characteristics of specific sequences that can differentiate epidermoid cysts. With multi planar cuts it offers, it remains the best technique to assess the extent and anatomical relationships of these cysts.