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Biomedical subjects

R Ethier

Publications and source records attributed to R Ethier.

84 records · Page 5Linked to original sources
PubMedDate not supplied

Primary ectopic meningioma of the neck: MR features.

Although meningiomas represent 15% of the tumors of the CNS, primary ectopic meningioma is a very rare finding. Four mechanisms for the formation of ectopic meningioma have been suggested: (a) direct extension of an intracranial lesion; (b) distant metastasis from an intracranial meningioma; (c) origin from arachnoid cells within the sheaths of cranial nerves; and (d) origin from embryonic nests of arachnoid cells. The case we present underwent a complete neuroradiological screening, and, although the neuroradiological findings were nonspecific to provide a correct diagnosis, they were useful for assessment of the tumor extension and for surgical planning. Particularly, magnetic resonance gave a panoramic view of the tumor and suggested its extensive vascularization, which was confirmed later by angiography.

Adult↗
PubMedDate not supplied

Low-grade myxoid chondrosarcoma of the base of the skull: CT, MR, and histopathology.

A retrospective CT, MR, and histopathologic study was performed in five patients with histologically verified low-grade myxoid chondrosarcoma of the base of the skull. In four patients, the tumor originated off the midline and was associated with bone destruction at the petrous apex near the petrooccipital fissure. Tumor extent included the cerebellopontine angle in three patients and the parasellar area in two patients. The fifth tumor originated on the midline and was associated with destruction at the dorsum sellae. Three tumors contained calcifications, whereas two lesions were mostly isodense with brain on CT scan. All tumors were hypointense on T1-weighted MR images and very intense on T2-weighted images except for areas of signal void consistent with calcifications. Light microscopy revealed islands of mature hyaline cartilage in an abundant myxoid ground substance. Histology and immunocytochemical analysis were consistent with a low-grade myxoid chondrosarcoma. The CT and MR features of low-grade myxoid chondrosarcoma are comparable with those of chordoma. Chordoma usually arises from the midline, but cases with origin from the lateral portion of the clivus or the petrous apex have been described. Low-grade myxoid chondrosarcoma has distinct histologic and immunocytochemical features and includes lesions formerly called "chondroid chordomas."

Adolescent↗
PubMedDate not supplied

MRI of amygdala and hippocampus in temporal lobe epilepsy.

In this study we compared the results of qualitative visual analysis of MRI with volumetric studies of the amygdala (AM) and hippocampal formation (HF) in a group of 31 patients. Twenty-six patients with temporal lobe epilepsy (TLE) and six with non-TLE had MRI studies using a 1.5 T Gyroscan following a specific protocol for scan acquisition. The MR images were interpreted by two blinded radiologists and by a third if discrepancy arose. Volumetric studies were carried out by one or two raters. The volumetric measurements of AM and HF were accurate in lateralizing the epileptogenic area in patients with TLE, concordant with the EEG in 92%; there was no false lateralization. In those patients who underwent surgery, there was a correlation between the degree of mesial temporal sclerosis demonstrated by histopathology, the amount of volume reduction, and the asymmetry. In patients with non-TLE, there was no volume asymmetry of AM or HF. The MR qualitative assessment yielded positive lateralization in patients with TLE in 56%, conflicting lateralization in 20%, and lateralization contralateral to the focus in 12%. A hyperintense signal in mesial structures was found ipsilateral to the focus in 40% and contralateral in 12% of patients with TLE. Volumetric study improves the diagnostic yield of MRI evaluation in patients with TLE not related to gross structural lesions. The interrater variability is low and the data are accurate and reproducible. Because they are quantitative, volumetric studies permit better comparison of results in different subgroups of patients with TLE.

Adolescent↗
PubMedDate not supplied

Leptomeningeal gliomatosis: MR findings.

We report a case of primary diffuse leptomeningeal gliomatosis documented by MR. The radiological findings guided the surgical biopsy toward the area involved. Pathological examination confirmed the diagnosis. The patient could consequently benefit from treatment, i.e., radiation therapy, which was followed by clinical relief.

Adolescent↗
PubMedDate not supplied

Intracerebral gangliogliomas in patients with partial complex seizures: CT and MR imaging findings.

The clinical and radiologic findings in 19 patients with partial complex seizures and surgically proved intracerebral gangliogliomas were reviewed to characterize the radiologic features of these lesions. The CT and MR findings were not specific. On CT the gangliogliomas can be hypodense with no enhancement and they often have calcifications. On MR these tumors have a wide variety of signals. In five of our cases the tumor had a high-intensity signal with a cystlike component on proton density- and T2-weighted images. In five cases the lesion had an inhomogeneously intense signal on proton density-weighted images and high signal intensity on T2-weighted images. The tumor had high-intensity signal on both proton density- and T2-weighted images in four patients. Finally, in two cases the MR findings were normal. We recommend MR as the examination of choice for patients with partial complex seizures because it allows an artifact-free evaluation of the temporal region. However, CT should also be performed in order to recognize calcifications that may be missed on the MR examination.

Adolescent↗
PubMedDate not supplied

Spinal angiolipomas: CT and MR aspects.

Spinal angiolipomas are rare benign tumors containing vascular and mature adipose elements. In greater than 90% of the cases they are located in the epidural space. The clinical symptomatology is nonspecific, but CT and particularly MR studies allow for a precise diagnosis. Computed tomography (four cases in the literature plus one explored in our department) showed a hypodense lesion in 80% of the cases. In one case the angiolipoma was isodense to the cord. Magnetic resonance (three cases in the literature plus two explored in our department) showed a more or less homogeneous mass with a signal in T1- and T2-weighted images close to that of the subcutaneous fat. The infusion of gadolinium (one case in the literature plus one of ours) is helpful as an indicator to the degree of vascularization of the angiolipoma.

Adult↗
PubMedDate not supplied

MR imaging of epidermoid cysts.

Nine patients with epidermoid cysts, five of them pathologically proved, were evaluated with MR imaging. Six patients also had CT. The cases were reviewed to evaluate the MR appearance of epidermoid cysts and to compare the MR findings with those of CT. The epidermoid cysts demonstrated low-signal intensity on T1-weighted MR images and hyperintensity on T2-weighted images. In five cases the cysts appeared heterogeneously iso- to hyperintense on the intermediate echo, and were surrounded by a thin rim of high signal intensity, which we believe was caused by encased CSF. The CT scans showed the cysts as low-density, well-demarcated lesions that do not enhance after infusion with contrast material. We conclude that MR is superior to CT in the evaluation of epidermoid cysts and is particularly useful in surgical planning.

Adolescent↗
PubMedDate not supplied

Stereoscopic digital subtraction angiography in neuroradiologic assessment.

Digital subtraction angiography (DSA) with stereoscopic imaging was performed in 40 patients for evaluation of a variety of cerebrospinal disorders. It was facilitated by a C-arm mounted x-ray tube and imaging chain with 7 degrees angulation between image pairs. Stereoscopic digital imaging proved particularly useful in the preoperative assessment of aneurysms, arteriovenous malformations, and primary and metastatic tumors. The technique was also found to be useful as a real-time adjunct to therapeutic radiographic procedures, as an aid in stereotaxic procedures, and in follow-up of postsurgical patients. Although the intravenous route was occasionally used, especially in postoperative follow-up of aneurysms, the procedure was most often carried out via an intraarterial approach. Stereoscopy was useful in supplying depth information regarding the relations between lesions and surrounding normal and abnormal vasculature. This technique combines the demonstrated advantages of intraarterial DSA with the unique advantage of stereoscopic imaging to demonstrate three-dimensional detail, thus contributing significantly to diagnostic confidence. Disadvantages are discussed. Further refinements in the equipment are expected: generation of stereo images with one injection, thus increasing procedure efficiency and patient safety; a video stereoscopic viewing unit; and the ability to obtain precise measurements via computer of depth, position, distance between, and true size of objects.

Adolescent↗