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V Lefournier

Publications and source records attributed to V Lefournier.

12 recordsLinked to original sources

[Brain perfusion and metabolism imaging techniques].

Due to recent efforts in improving spatial and temporal resolution in imaging techniques, it is now possible to get relevant information about brain perfusion and metabolism in humans. This information can significantly impact on brain pathophysiology, diagnosis assessment and therapy options, particularly in patients having brain ischemia. Among these imaging and metabolism techniques are dynamic perfusion computed tomography, perfusion MRI, positron emission tomography and NMR spectroscopic imaging. The goal of this article is an overview of these four techniques, with their own technical description, advantages and drawbacks. Details are provided about brain parameters given by each technique and their clinical relevance, the accessibility of the technique in the emergency setting and the optimal window to use it during the patient's evolution.

Brain↗

[Perfusion-diffusion 1H spectroscopy: role in the diagnosis and follow-up of supratentorial brain tumours in adults].

INTRODUCTION: In a few years, magnetic resonance imaging (MRI) has evolved from a morphology-based examination to one that encompasses metabolism and function. STATE OF ART: MRI is a well-established tool for the initial evaluation of brain tumors, but conventional MR sequences have some limitations. Conventional MRI is unable to distinguish high-grade glioma from metastasis and abscess, to define precisely the histopathological grade of gliomas, to determine exactly the limits of tumor extension, to characterize meningeal tumors. Differentiation of tumor recurrence from treatment-related changes may be difficult with standard MR imaging because the interpretation is essentially based on volume analysis. PERSPECTIVES: 1H Spectroscopy, diffusion and perfusion imaging become possible with the development of MR imagers and can be routinely performed in clinical settings. They give complementary information about tumor metabolism and vascularity and allow a better analysis of post-treatment modifications. Functional and metabolic explorations should be used to characterize brain tumors.

Adult↗

[Perfusion MR imaging in brain tumors].

Perfusion MR Imaging is useful for initial diagnosis and follow up of brain tumors. Dynamic susceptibility contrast MR imaging is described. The limitations and advantages of this technique are discussed with respect to quantification and interpretation of results.

Brain Neoplasms↗

[Magnetic resonance cerebral blood volume maps. Comparison with histologic findings in different types of brain lesions].

Recent developments in magnetic resonance (MR) have made it possible to obtain measurements of the microvasculature within brain lesions. Cerebral blood volume (CBV) maps calculated from dynamic contrast-enhanced MR imaging are particularly sensitive for depicting the microvasculature, and can enable the detection of neovascularization as well as its quantification in relative terms. The purpose of the present work is to compare the results of CBV maps calculated from MR imaging with those from histologic examination of the same region of interest: the biopsy site. Nineteen patients with brain lesions were studied (18 brain tumors and one case of multiple sclerosis). All patients underwent stereotactic biopsy, and calculation of CBV was performed from perfusion MR imaging. Three histopathologic parameters were assessed: the number of vessels (vessel density), the vessel size and the surface area filled by vessels (%). We observed a statistically significant correlation between the vessel density and the CBV, which is consistent with some previous publications. A noninvasive imaging method for characterizing the functional properties, especially hemodynamic activity, of malignant processes seems to be of great benefit to clinical practice.

Adult↗

Cerebral blood volume mapping by MR imaging in the initial evaluation of brain tumors.

PURPOSE: To assess the contribution of magnetic resonance (MR) cerebral blood volume (CBV) mapping in the initial evaluation of brain tumors. METHODS: 63 patients presenting a brain tumor underwent dynamic susceptibility-contrast MR imaging before surgery or biopsy: 28 high grade gliomas, 8 low grade gliomas, 2 pilocytic astrocytomas, 4 lymphomas, 12 metastases, 9 meningiomas. The CBV maps were obtained for each patient and the relative CBV (rCBV) in different areas was calculated using the ratio between the CBV in the pathological area (CBVp) and in the contralateral normal tissue(CBVn). The maximum rCBV (rCBVmax) for each tumor was determined and the mean values of rCBVmax in each group of tumors were compared using an unpaired Student t test (p=0.05). RESULTS: The rCBVmax for high grade gliomas (mean +/- SD: 2.6 +/- 1,2) was statistically different from low grade gliomas (0.9 +/- 0.4) (p<0.001), lymphomas (0.7 +/- 0.2) (p=0.002), meningiomas (9.1 +/- 4.4) (p<0.001) and kidney metastases (8.9 +/- 2.1) (p<0.001). The two pilocytic astrocytomas had a much lower rCBVmax than high grade gliomas. No statistically significant difference was found between high grade gliomas and lung metastases (2.4 +/- 0.9) (p=0.72). CONCLUSION: CBV mapping provides additional information on the vascularity of the lesions, which is not available with conventional MR imaging. It might be useful for differentiating certain lesions showing contrast enhancement, mainly high grade gliomas from kidney metastases, meningiomas, lymphomas or pilocytic astrocytomas.

Blood Volume↗

A persistent pharyngohyostapedial artery: embryologic implications.

A 3-year-old child was examined because of otorrhagia. CT scans showed an unusual vessel, confirmed by angiography, related to a persistent pharyngohyostapedial artery. This embryonic persistent artery associated with the normal internal carotid artery would explain the "duplication" aspect of the internal carotid artery.

Angiography, Digital Subtraction↗

[Benign vertebral osteoblastoma. Report of 6 cases].

We present six cases of benign spinal osteoblastoma. This localization of this uncommon benign bone tumor occurring in young subjects is rare. The patients were explored with radiotomography, computed tomography, myelography and medullo-spinal angiography. These benign tumors may appear radiographically as pure bone lysis mimicking malignancy. The size of these tumors often leads to widening search for extension, particularly in recurrent, aggressive, multifocal forms which require wide resection, and sometimes total vertebrectomy. Medullo-spinal angiography can confirm the vascular involvement of the tumor nidus and is require to identify arteries supplying the spinal canal which would modify operative strategy.

Adolescent↗

[Intracranial dural fistula with spinal cord venous drainage. Apropos of 2 cases].

The authors report 2 new cases of intracranial dural fistula draining into spinal veins. Comparisons with 19 other published cases showed that dural fistulae of the spine share common features with intracranial fistulae. The first case concerned a 78-year old woman presenting with a thoraco-lumbar myelopathy which proceeded by increasingly severe bouts and ended within 6 months in a flaccid sensorimotor paraplegia with urinary incontinence. Paraclinical examinations consisted of MRI, myelography and spinal as well as cerebral arteriography. MRI and thoraco-lumbar myelography displayed marks of dilated retrospinal vessels. Spinal arteriography showed no arteriovenous malformation, but the venous return of Adamkiewicz artery was not visible. Diagnosis was made by cerebral arteriography which demonstrated an intracranial arteriovenous fistula in the occipital region, draining into the posterior spinal vein. Treatment was endovascular and consisted of embolization by micro-coils, but clinical improvement was mediocre. Six months later, as the clinical picture was getting worse a second arteriography was performed. It showed recanalization of the fistula which was embolized again, using both coils and particles. No improvement in spinal cord deficit was observed. The second case was that of a 42-year old man presenting with paraparesis, tetrapyramidal syndrome, sensory deficit at T9, peribuccal dysaesthesias and genito-urinary sphincteral disorders, all gradually getting worse. The paraclinical exploration was the same as in the first case. MRI and myelography showed retrospinal vascular impressions. Spinal arteriography was normal, except for the lack of venous return of Adamkiewicz artery. Cerebral arteriography detected an intracranial dural arteriovenous fistula in the occipital region, draining into the anterior and posterior spinal veins. Treatment was surgical, consisting of exclusion of the arteriovenous fistula. Partial clinical improvement was noted. These two cases, compared with those of the literature, shared a number of features with spinal dural arteriovenous fistulae: they occur in middle-aged and predominantly male patients, and the clinical signs of ascending myelopathy are caused by the same physiopathological mechanism of spinal vein hyperpressure. Lesions of the medulla oblongata or the cervical spinal cord are found only in intracranial arteriovenous fistulae draining into spinal veins. Diagnosis is based on data provided by myelography (impressions of dilated and sinous vessels) and MRI (low-intensity perispinal signals, widening of the conus medullaris with high-intensity centrospinal signal); spinal cord angiography only shows a lack of venous return of Adamkiewicz artery without any other abnormality, whereas cerebral arteriography confirmed the diagnosis of intracranial dural arteriovenous fistula draining into spinal veins.

Adult↗

[Computed tomographic aspects of secondary cholesteatomas of the middle ear and petrous bone].

The authors present their experience of secondary cholesteatomas of the middle ear explored by computerized tomography (CT). Following a brief anatomicopathological description of secondary petrous bone cholesteatomas, and of the CT technique used for their exploration, they describe and illustrate the classical "bag-shaped" internal or external attical forms usually extended to the antrum and the mastoid process, and the less common locations often due to relapse or postoperative recurrences (anterior hypotympanic or posterior mastoidal). The holotympanic forms, usually due to "lamellar" cholesteatomas, create diagnostic problems with other opacities in the cavity, as also do certain forms that are evacuated spontaneously or by aspiration. One of the qualities of CT lies in the preoperative extension assessment. The lesion may extend towards the internal wall of the cavity (lateral semicircular canal, second portion of the facial nerve), towards the labyrinth to the petrosal apex and/or the geniculate ganglion, and above all towards the inferior labyrinth which might bring the cholesteatoma into contact with large vessels (e.g. jugular vein bulb for postero-inferior extensions, carotid canal for antero-inferior extensions). Extension into anfractuosities of the cavity walls (sinus tympani, subratubal fossette) must be systematically looked for in order to avoid postoperative recurrences.

Bone Diseases↗

Direct emergence of the dorsospinal artery from the aorta supplying the anterior spinal artery: report of two cases.

We report two cases of an isolated dorsospinal artery that emerged directly from the aorta to supply the anterior spinal artery, which in one case had another blood supply on the opposite side, in a lower position. It is important to identify this anatomic variant, otherwise spinal angiography might be incomplete, especially when the isolated dorsospinal artery supplies the anterior spinal artery.

Adult↗