PubMed Health⌕ Search

Biomedical subjects

G Salamon

Publications and source records attributed to G Salamon.

At least 19 recordsLinked to original sources
PubMed1992

Cortical region of interest definition on SPECT brain images using X-ray CT registration.

We present a method for brain single photon emission computed tomography (SPECT) analysis based on individual registration of anatomical (CT) and functional (133Xe regional cerebral blood flow) images and on the definition of three-dimensional functional regions of interest. Registration of CT and SPECT is performed through adjustment of CT-defined cortex limits to the SPECT image. Regions are defined by sectioning a cortical ribbon on the CT images, copied over the SPECT images and pooled through slices to give 3D cortical regions of interest. The proposed method shows good intra- and interobserver reproducibility (regional intraclass correlation coefficient approximately 0.98), and good accuracy in terms of repositioning (approximately 3.5 mm) as compared to the SPECT image resolution (14 mm). The method should be particularly useful for analysing SPECT studies when variations in brain anatomy (normal or abnormal) must be accounted for.

Blood Flow Velocity↗
PubMed1992

[Interhemispheric transfer in multiple sclerosis. Morphofunctional correlations].

Signs of cerebral disconnection, especially left ear suppression to dichotically presented verbal stimuli, have been reported in multiple sclerosis patients and found to be correlated to morphological atrophy of the corpus callosum on magnetic resonance imaging. To reinvestigate this issue, 26 patients satisfying criteria for definite multiple sclerosis were proposed 3 tasks aimed at evaluating interhemispheric function: a dichotic listening task, a motor finger-tapping task and a sensory transfer task. Performance at these tasks suggested impaired callosal function in MS patients, compared to normal controls. Callosal morphology was assessed on midsagittal MRI sections using a digitalised method of partition of the callosal area into 6 subregions and automatized surface measurements. Results of correlations between task performance and callosal areas showed a significant correlation between total callosal atrophy and severity of interhemispheric impairment on each functional task. Moreover, impaired motor transfer was specifically related to atrophy of the anterior callosal regions. These results suggest that MS patients may constitute a suitable population to studying interhemispheric transfer of information through the callosal commissure and that this approach may be useful in the clinical management of MS patients.

Adolescent↗
PubMed1992

Value of MRI in the morphological evaluation of tumors of the third ventricle.

The detection or suspicion of a tumoral expansive process in the third ventricule is usually performed by MRI. The contribution of MRI to the diagnosis is unquestionable in view of its accuracy in the topographical characterization of these lesions and in the detection of small formations. The great histological variety of tumours in that region may result in different treatments which can be associated. MRI, therefore, plays an important role in pretherapeutic morphological evaluation. Fifteen patients with tumour of the third ventricle were examined by MRI before treatment. The results of these examinations were compared with the pathological data and the therapeutic procedures: ventricular shunting, stereotactic needle biopsy, radio- or chemotherapy and surgery. MRI cannot provide a formal histological characterization, but it can individualise some categories of tumours, give details on the walls of the third ventricle (notably in the case of bifocal pineal and suprassellar lesions), visualize the paths of CSF flow and predict the need for cisternoventriculostomy, and detect venous structures in the vicinity of the great cerebral vein which might result in post-biopsy and post-surgery complications.

Adolescent↗
PubMed1991

Effects of handedness and sex on the morphology of the corpus callosum: a study with brain magnetic resonance imaging.

In view of conflicting data in the existing literature, we examined 53 normal subjects using a handedness questionnaire and callosal area measurements obtained from midsagittal MRI images. The callosum was found to be significantly larger in nonconsistent right-handers (NCRH), especially in its anterior half and especially for males. A significant hand x sex interaction, favoring consistent right-handed (CRH) females, was also found for the posterior midbody, a region known to house interhemispheric fibers connecting the right and left posterior association cortices. These results (1) confirm Witelson's (1985) first findings on postmortem specimens; (2) validate a dichotomy between CRH and NCRH rather than simply considering the writing hand, as was the case in most other similar studies; and (3) suggest that at least two different sex-related--probably hormonal--factors may be acting during the callosal development, one explaining the larger anterior half in NCRH males and the other the larger posterior midbody in CRH females.

Adolescent↗
PubMed1991

Topographical study of supratentorial brain tumors.

The topographic analysis of supratentorial brain tumors must answer the following questions: location of the tumor, its extension, its being infiltrative or well localized and especially the relationships with the main functional areas such as the speech areas, the sensori-motor area, and the visuel areas. Also the topographic analysis may help to approach the diagnosis of nature. The neuroradiological procedures include the CT, the angiography and especially the MRI in sagittal and coronal sections, with gadolinium enhancement. The anatomical accuracy is obtained using the bicommissural plane and superimposition techniques according to the Talairach's Atlas and anatomical sections and MRI superimposition with angiography. 3D volumic reconstruction is of considerable contribution for the topographic analysis of a cerebral tumor.

Angiography↗
PubMed1991

Astrocytic tumours.

Astrocytic tumours are frequent, accounting for nearly 50% of all brain tumours. They are divided into three groups: benign astrocytomas, anaplastic astrocytomas and malignant glioblastomas. The usual clinical manifestations of benign astrocytic tumours are epileptic seizures, whereas those of glioblastomas are rapidly progressing neurological deficits. These lesions show fairly characteristic neuroradiological features which have been largely studied. Injections of iodine-based or paramagnetic contrast media are important since they help in tumour grading: low-grade tumours are not enhanced, while glioblastomas are almost invariably enhanced. MRI seems to be indispensable for the study of astrocytic tumours: it provides an excellent anatomical analysis of the lesion during preoperative or pretherapeutic evaluation, and it is the only available method to confirm low-grade lesions that have passed unnoticed or have merely been suspected at CT. To avoid missing these tumours, every adult presenting with recent onset epileptic seizures should be explored by MRI using T2-weighted spin-echo sequences.

Adult↗
PubMed1991

Oligodendrogliomas.

Oligodendrogliomas are tumours developed from oligodendrocytes. They may be pure or associated with astrocyte proliferation. They are usually benign, but their malignancy grade is varied. These tumours affect middle-aged adults and are characterized by their slow growth and their fairly suggestive neuroradiological features which are those of a large, calcified, poorly enhanced, peripheral frontal lesion. Computerized tomography and magnetic resonance imaging are suitable complementary methods to characterize the tumour and evaluate its extension.

Adult↗
PubMed1991

Magnetic resonance imaging in gangliogliomas and gangliocytomas of the nervous system.

Gangliogliomas and gangliocytomas are rare and benign neuronal tumors which affect young subjects. This study concerns 3 cases of ganglioglioma and 3 cases of gangliocytoma explored by CT and MRI and confirmed by pathological examination. The most typical CT image was that of an often calcified contrast-enhanced cystic tumor. At MRI, each tumor emitted a low-intensity signal on T1-weighted sequences and a high-intensity signal on T2-weighted sequences. Contrast enhancement after gadolinium injection was frequent. Neuroradiology is not specific, and these tumors are usually diagnosed at pathology. However, the diagnosis may be considered in young patients with a history of old, drug-resistant partial epilepsy and having a contrast-enhanced, calcified cystic lesion in the temporal lobe or the cerebellum.

Adolescent↗
PubMed1990

[Gadolinium-DTPA in the study of intracranial tumors in the adult].

Thirty intracranial tumours were explored by MRI, using T1- and T2-weighted sequences, before and after intravenous injection of Gd-DTPA. Two-thirds of the intra-axial tumours were accurately detected on one section plane by MRI without Gd-DTPA, but in one quarter of the cases Gd-DTPA only delineated precisely the tumour. On the other hand, Gd-DTPA failed to detect certain tumours (benign gliomas) or showed only a small part of them (mixed grade gliomas), while they were detected by MRI without contrast injection. However, in such cases Gd-DTPA was useful for the stereotaxic biopsy of the tumour. Gd-DTPA appears of lesser interest in extra-axial tumours. Gd-DTPA is thus valuable for the neuroradiological diagnosis of brain tumours, particularly to evaluate the grade of gliomas and to confirm the diagnosis of recurrent growths.

Adult↗
PubMed1990

[Standardization of the anatomic study of the brain stem in x-ray computed tomography and magnetic resonance imaging].

The presence of flexures between the mesencephalon, pons and medulla oblongata implies the definition of specific orientations of axial sections for each level of the brain stem. These axial sections have to be perpendicular to the axis of the corresponding segment. For the mesencephalon, we have defined an axis corresponding to a straight line of best fit to the mesencephalic anatomical axis; the whole of the rhombencephalon has been referred to an axis taken through the pons and the intracranial medulla that is tangential to the floor of the IV ventricle. Identical reference planes can be obtained in CT by programming, on the scout view of the skull, perpendicular sections of the clivus that allow the study of the axial aspect of the mesencephalon, with sections at - 7 degrees through Chamberlain's line for visualization of the same aspect of the rhombencephalon. We have thus defined the referential planes to analyse every level of the brain stem using reproducible axial sections, able to be applied to different patients as well as to different examining techniques (TDM, MRI).

Adult↗
PubMed1989

Spontaneous dissection of both extracranial internal carotid arteries.

Neurological examination and Doppler sonography of a 50-year-old patient were suggestive of a spontaneous dissection of the left internal carotid artery (left-sided headaches, amaurosis fugax, Horner's syndrome and hemispheric stroke). Four-vessel angiogram performed several days after the onset of the symptoms showed dissection of both extracranial carotid arteries, more pronounced on right side where the dissection was clinically asymptomatic. Angiogram follow-up demonstrated a recanalization of both carotid arteries. A review of 15 other documented reports indicates that bilateral internal carotid dissection is usually associated with fibromuscular dysplasia. A large majority of cases does not clinically differ from unilateral carotid artery dissection.

Carotid Artery Diseases↗
PubMed1989

[Digital arteriography using an intra-arterial route in vertebrobasilar insufficiency. Comparison of iopromide 300 and ioxaglate 320 mgI/ml].

During intra-arterial digital subtraction angiography of the vertebral and basilar arteries, 24 patients were included in a prospective double-blind randomized trial comparing a new non-ionic contrast medium, iopromide 300 and an ionic low osmolar medium, ioxaglate 320 mgI/ml. There was a statistically significant reduction in the number of adverse effects observed with Iopromide 300, particularly in terms of unwanted movements, source of image quality degradation.

Angiography, Digital Subtraction↗
PubMed1987

Age-related changes in aphasia type and stroke location.

Two-hundred consecutive CT scans of patients with an infarction in the territory of the middle cerebral artery (MCA) were examined for evaluation of a possible relationship between age and stroke location. Two distinct procedures, one evaluating the incidence of four areas within the MCA territory and the other measuring some quantified parameters, were used. Statistical studies failed to show any significant correlation between these parameters and the age of patients. These results lead to refute previous claims that semiological changes in aphasia type with age in stroke patients may be due to a posterior shift of cerebral infarcts with age.

Adult↗
PubMed1979

Correlative study between computerized transverse scanning and stereoimpedoencephalography in space-occupying lesions of the brain.

Stereoimpedoencephalography (SIEG) is routinely used by the authors during stereotactic investigations of glial brain tumours prior to stereotactic implantation of isotopes or prior to conventional surgery: the brain tissue impedance is measured along a probe track according to the four electrodes impedance technique. The correlation between the tissue structures and the corresponding impedance values has been studied by comparison with the CATScan data reported on the stereotactic schedules; impedance values are influenced by changes in arterial pCO2 and also by other unknown factors; in order to avoid these uninterpretable changes of the impedance, the recorded values have been normalized with respect to the average impedance along a control track in the normal hemisphere. As a rule, the impedance profile exhibits a "hole" at the site of the pathological processes like tumours as well as surrounding oedema, and the delimitation of the pathological area is very similar to that obtained by the CATScan. There is a good linear correlation between the values of normalized impedance and the x-ray absorption as given by the computer listing of the CATScan. Lastly, statistical values of normalized impedances are determined for the main structures of the brain, showing that the tumour tissue has an impedance equal to half the impedance of the normal tissue.

Brain Neoplasms↗
PubMed1978

Investigations of nontumoral hydrocephalus in children.

An analysis was made of 175 cases of pediatric nontumoral hydrocephalus. CT scan by itself permits a precise diagnosis in only one-third of the cases. However, when the clinical context suggests that hydrocephalus is secondary to certain conditions such as infection, bleeding, or trauma, CT scan may suffice, unless more advanced investigation permits more efficient treatment. When hydrocephalus is associated with brain malformations, however, more complete investigation is needed for a better understanding of the condition. Conventional contrast studies are quite safe, especially ventriculography which is easy to perform in this type of patient, who is usually investigated during the first 12 months of life.

Age Factors↗