Biomedical subjects

J Vignaud

Publications and source records attributed to J Vignaud.

At least 19 recordsLinked to original sources

PubMed1997

MR imaging of acoustic neuroma with high resolution fast spin echo T2-weighted sequence.

OBJECTIVE: To assess the value of high resolution 2D fast spin echo T2-weighted sequence (HR 2D-FSE T2w) for evaluating the internal auditory meatus (IAM) in patients with asymetric or unilateral sensorineural hearing loss, vs. gadolinium-enhanced T1-weighted (T1w) sequence; to suggest a screening protocol to exclude the diagnosis of acoustic neuroma in a patient with isolated unilateral sensorineural hearing loss. MATERIALS AND METHODS: One-hundred ten patients with suspected acoustic neuroma were evaluated with 1.5 T MRI system. The protocol included axial images focused on the IAM: HR 2D-FSE T2w images (4000/63, ETL = 16, 3-mm sections with 1.5 mm overlap, 18 FOV, 512 x 384 matrix) and gadolinium-enhanced T1w images (600/23, 3-mm sections, 18 FOV, 256 x 192 matrix). Two criteria for normality of the HR 2D-FSE T2w examination are defined: high homogeneous signal of the cerebellospinal fluid (CSF) and linear low signal of the nerves visible throughout the IAM. RESULTS: Overall results show no false-negative and six false-positive with HR 2D-FSE T2w sequences vs. gadolinium-enhanced T1w sequences. The sensitivity of HR 2D-FSE T2w sequences is 100%, specificity 93%, and negative preditive value 100%: normal images using HR 2D-FSE T2w sequence can rule out the diagnosis of acoustic neuroma. CONCLUSION: Using this protocol we can exclude the diagnosis of acoustic neuroma in case of normal HR 2D-FSE images and no additional gadolinium-enhanced T1w sequence is necessary. This protocol might reduce examination time, must promote recourse to MRI in the event of clinical suspicion of acoustic neuroma, and also enables savings by proposing MRI examination as a first-line exam.

Adult↗

PubMed1996

Magnetic resonance imaging assessment of labyrinthine pathology.

Membranous labyrinth pathologies are quite rare. They were until recently difficult to demonstrate by imaging technics, CT being the modality of choice. Our purpose was to stress the interest of MR examination for investigating patients complaining of vertigo, tinnitus, and profound sensorineural hearing loss. Normal anatomy as well as the main pathologically encountered changes are illustrated.

Ear Diseases↗

PubMed1995

Imaging of the vestibule.

PURPOSE: State-of-the-art imaging of the normal and pathologic vestibule. METHODS AND MATERIAL: This study is based on the experience of three French imaging centers (Val de Grâce, Bégin, and Saint-Antoine hospitals) working with 1- and 1.5-tesla magnetic resonance units and high-resolution computed tomography, and it includes a review of the literature. Computed tomography is performed with a high-resolution program, matrix 512 x 512, field of view 9.6 cm, joined 1-mm section, overlapped sections every 0.5 mm, axial and coronal sections, or reformatted images. High-resolution magnetic resonance imaging (matrix 512 x 384), field of view 18 cm, is used with fast T2-weighted sequences (sections 3 or 2 mm thick, constructive interference in steady state, T2-weighted gradient echo sequence three-dimensional Fourier transformation). A joined section of 0.7 mm in any direction is obtained if necessary. Superimposition of computed tomography and magnetic resonance imaging with a stereotactic technique by identification of identical anatomic points is sometimes used. RESULTS: We review the interest and place of computed tomography and magnetic resonance imaging in the diseases of the labyrinth and internal auditory canal related to abnormal vestibular functions: inflammatory labyrinthitis, vestibular hemorrhages, sclerosing and ossifying labyrinthitis, traumatism, malformations, perilymphatic fistulas, otosclerosis, tumors, cochleovestibular neuritis, and hydrops of the endolymphatic system.

Humans↗

PubMed1992

[MRI techniques for the study of the temporal lobe and its environment].

The MR study of the temporal lobe and its environment requires a good knowledge of the anatomy in order to select the views adapted to the disease investigated. The authors propose a series of protocols according to the region examined. An understanding of the principles of MR sequences is also essential to avoid the problems of investigation associated with this complex anatomical region. The principal sequences are reviewed together with their advantages and disadvantages.

Cerebellopontine Angle↗

PubMed1989

[Diagnosis of disorders affecting the auditory apparatus].

The advent of new imaging techniques, such as computerized tomography and magnetic resonance imaging, have modified the classical methods used to explore the auditory system. At the present time, computerized tomography remains the technique of choice for the study of inflammatory, traumatic or malformative lesions of the ear, but it has been superseded by magnetic resonance imaging in the study of tumours of the internal auditory canal and of the cerebellopontine angle.

Angiography↗

PubMed1988

Separation of diffusion and perfusion in intravoxel incoherent motion MR imaging.

Intravoxel incoherent motion (IVIM) imaging is a method the authors developed to visualize microscopic motions of water. In biologic tissues, these motions include molecular diffusion and microcirculation of blood in the capillary network. IVIM images are quantified by an apparent diffusion coefficient (ADC), which integrates the effects of both diffusion and perfusion. The aim of this work was to demonstrate how much perfusion contributes to the ADC and to present a method for obtaining separate images of diffusion and perfusion. Images were obtained at 0.5 T with high-resolution multisection sequences and without the use of contrast material. Results in a phantom made of resin microspheres demonstrated the ability of the method to separately evaluate diffusion and perfusion. The method was then applied in patients with brain and bone tumors and brain ischemia. Clinical results showed significant promise of the method for tissue characterization by perfusion patterns and for functional studies in the evaluation of the microcirculation in physiologic and pathologic conditions, as, for instance, in brain ischemia.

Bone Neoplasms↗

PubMed1987