Cystic Solitary Fibrous Tumor Arising From the Left Occipital Meninges: A Case Report

Solitary fibrous tumor (SFT) is a benign mesenchymal neoplasm of a spindle-cell origin, and it usually involves the pleura. It's occurrence in various organs of the body has recently been described. Meningeal SFT is very rare. Radiologically, it is a strongly enhancing solid mass and is undistinguishable from fibrous meningioma and hemangiopericytoma. Yet we report here on a case of SFT with massive cystic degeneration that arose from the meninges of the left occipital region.

Clear-Cell Meningioma: CT and MR Imaging Findings in Two Cases Involving the Spinal Canal and Cerebellopontine Angle

Clear-cell meningioma is a rare subtype of meningioma which occurs at a younger age and has a higher recurrence rate than other subtypes. We report two cases of clear-cell meningioma, one in the thoracolumbar spinal canal and the other in the cerebellopontine angle. Though the CT and MR imaging findings were not different from those of ordinary meningioma, after surgical removal the condition recurred repeatedly in the patient with spinal canal involvement.

MR Findings of Atypical Meningioma: Comparison with Benign Meningioma

PURPOSE: Atypical meningioma is an intermediate type, between benign and malignant meningiomas, and has ahigher recurrence rate and poorer prognosis than the benign type. The purpose of this study was to evaluate thedifferential imaging findings between atypical and benign meningiomas. MATERIALS AND METHODS: Over a five-yearperiod, 11 acses of atypical meningioma (in ten patients) were pathologically proven, and 30 benign meningiomaswere collected consecutively over 6 months. In retrospective analysis, the MR findings of atypical and benignmeningiomas were compared with respect to tumor respect to tumor margin, lobulation, intra-/peritumoralhemorrhage, cystic change, heterogeneity peritumoral edema, enhacement of adjacent meninges, invasion of adjacentvenous sinus and adjacent bony change. RESULTS: Significant differential MR findings between the two groups wereill-defined tumor margin(atypical-27%;benign-0%), lobulation(82%;43%), heterogeneity(73%;30%), and peritumoraledema(100%;47%). With regard to moderate edema, there was no significant difference between the twogroups(36%;23%), and with regard to intra-/peritumoral hemorrhage, cystic change, enhancement of adjacentmeninges, invasion of adjacent venous sinus, and adjacent bony change, MR findings between the two groups were notsignificantly different. CONCLUSION: The MR findings of atypical meningioma are significantly different inseveral ways from those of benign meningioma, and these differences may help differentiate the two types.

Diffuse Pachymeningeal Enhancement on Brain MRI: Spontaneous Intracranial Hypotension and Head Trauma

PURPOSE: We evaluated the MRI finding of pachymeningeal enhancement in patients with intracranial hypotensionand head trauma with particular attention to differential findings and change in follow-up study, and in order tosupport the knowledge about the pathophysiology of dural enhancement. METHODS AND MATERIALS: The findings ofenhanced brain MRI of fifteen patients who showed diffuse pachymeningeal enhancement were retrospectivelyexamined. Seven of fifteen patients were finally diagnosed as spontaneous intracranial hypotension(SIH). Eight offifteen patients had a recent history of head trauma. We analyzed the shape, thickness, continuity and extent ofdural enhancement, and the others concerned with positive MR findings. We also analyzed findings suggesteddisplacement of brain parenchyma- displacement of the iter and cerebellar tonsil, and flattening of the anterioraspect of the pons-. Four of seven patients with SIH and four of eight patients with head trauma, underwentfollow-up MRI. In the follow-up study, the presence of resolving pachymeningeal enhancement and symptomimprovement was investigated. RESULTS: In all cases of SIH, the dura showed diffuse, even 3(1mm thick, global andcontiguous enhancement along both cerebral convexities, both tentoria, and the falx. Displacement of the iter wasnoted in six cases and flattening of the anterior aspect of the pons in five. Displacement of the cerebellartonsil was noted in one case. Five of seven cases showed small amount of subdural fluid collection. In all casesof head trauma, the dura was enhanced diffusely and asymmetrically, and showed no contiguity. Its distribution wasconsistent with the locations of traumatic lesions. Displacement of the iter was noted in one case. In four casesof SIH, clinical symptoms had improved, and three showed complete resolution of dural enhancement, in one patientcontinuously showed partial dural enhancement. Four cases of head trauma showed complete resolution of duralenhancement. CONCLUSIONS: Reversible diffuse pachymeningeal enhancement and additional findings in brain MRI ofSIH and head trauma are valuable for differenciation from other irreversible pathological conditions related topachymeningeal enhancement and to support the knowledge about pathophysiology of dural enhancement.

Dural Tail Sign in MR Imaging of Nasopharyngeal Cancer

PURPOSE: To describe the dural tail sign in contrast-enhanced MR images of nasopharyngeal carcinoma (NPC). MATERIALS AND METHODS: MR images of 19 consecutive patients, in whom three years previously squamous cell type NPC had been pathologically proven, were reviewed for the presence or absence, location and direction of the dural tail sign and the relationship between this sign and the skull base invasion. Histopathologic specimens obtained in two patients were also described. RESULTS: In ten patients (53%), there was bony invasion of the skull base; in seven of these (37%), dural tails were found. In seven, this tail extended along the floor of the middle cranial fossa; in 5, along the petro-clivus, and in 4, along the tentorium. In all these cases, the adjacent skull base was involved. Histopathologic examination in two patients with dural tails in the middle cranial fossa revealed fibrosis and hyper-vascularity of the dura mater without evidence of tumor cell infiltration. CONCLUSION: The dural tail sign appears to be not infrequent in patients with advanced NPC. The dural tail may be a good indicator of intracranial tumor spread.

Brain MRI Findings of Spontaneous Intracranial Hypotension

PURPOSE: To evaluate brain MRI findings of spontaneous intracranial hypotension. MATERIALS AND METHODS: A retrospective review of MRI findings was conducted on six patients with clinically proven spontaneous intracranial hypotension ; no patient had history of previous spinal puncture. Follow-up MRI was available in two patients, and to detect CSF leakage, radionuclide cisternography (n=5), myelography (n=1), and MR myelography (n=1) were performed. RESULTS: On contrast-enhanced T1WI, diffuse dural enhancement was seen in all cases, subdural hematoma or hygroma was seen in four cases, pituitary gland prominence in four, dural sinus dilatation in four, downward displacement of cerebellar tonsil in two, downward displacement of iter in one, and suprasellar and prepontine cistern effacement in two. In no patient was abnormal CSF leakage found. CONCLUSION: Although dural enhancement, as seen on MRI, is not specific, diffuse enhancement of dura matter accompanying by subdural hematoma, hygroma, pituitary gland prominence, dural sinus dilatation, downward displacement of the cerebellar tonsil, or suprasellar and prepontine cistern effacement can strongly suggest intracranial hypotension.

Experimental Bacterial Meningitis in Rabbit : Evaluation with CT and MRI

PURPOSE: The purpose of this study was to evaluate the usefulness of computed tomography(CT) and magnetic resonance imaging(MRI) in experimental bacterial meningitis. MATERIALS AND METHODS: CT and MR images of experimental bacterial meningitis were obtained after inoculation of 1ml suspension of 106/ml Staphylococcusaureus directly into the supratentorial arachnoid space of 18 New Zealand white rabbits. Each animal was studied with both Pre-enhanced and post-enhanced CT and MRI at 12, 24, 48 hours and 1 week. Cerebrospinal fluid of all of18 rabbits were sampled and cultured for bacterial growth. RESULTS: All of 18 rabbits had the clinical symptoms such as neck stiffness and anorexia within 24 hours after the inoculation. Cerebrospinal fluid cultures werepositive for Staphylococcus sureus growth. Gd-enhanced MRI exhibited diffuse enhancement along the thickened supratentorial meninges earlier than CT. in Gd-enhanced MRI, the mean contrast enhancement ratio(CER) at supratentorial meninges increased to 1.93 at 12 hours and 2.99 at 24 hours from 1.06 at 0 hour. Histologic evaluation demonstrated inflammatory cell infiltration into the meninges. MRI also identified the complications of mening it is such as ependymitis and hydrocephalus more effectively than CT. CONCLUSION: These results indicatedthat Gd-enhanced MRI detected earlier the abnormal findings of bacterial meningitis and evaluated more effectively the complications of mening it is compared with CT. MRI was more useful than CT in evaluation of the bacterial meningitis.