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Biomedical subjects

D Doyon

Publications and source records attributed to D Doyon.

At least 19 recordsLinked to original sources
PubMed1992

[MRI of the spinal epidural fat in pathology].

The authors report about their experience with the merits of the normal systematization of epidural fat with MRI. On sagittal sections, this fat has a variable appearance, but its location along the spinal canal is constant. On axial sections, its morphology is suggestive of the level of section: cervical, upper or lower thoracic, lumbar. Some changes in this fat are precious data to explain local hypertrophy (scoliosis) or to locate an intra- or extradural process.

Adipose Tissue↗
PubMed1992

[MRI of normal spinal epidural fat].

The authors perform a retrospective study of 65 spines examined with MRI. They specify the distribution of normal posterior epidural fat and establish the relationship between the anteroposterior thickness of epidural fat and the sagittal diameter of the spine on axial sections. On sagittal sections, the fat has a variable appearance, but a constant location along the spinal canal.

Adipose Tissue↗
PubMed1992

[X-ray computed tomography in preoperative assessment of oral implants].

The authors report their experience and method for computed tomography of maxilla and mandible before endosseous implant surgery. CT defines indications of implant surgery, avoiding useless operations and sometimes allowing implant surgery that seemed impossible on standard X-rays. It provides good preoperative assessment, precising diameter and length of implant, exact location and state of anatomic structures to be avoided, quality of bone and ideal implant axis.

Adolescent↗
PubMed1992

[MRI of malformative syringomyelia. Descriptive and developmental aspect].

132 cases of malformative syringomyelia have been studied at the C.I.E.R.M. (Interdepartmental Magnetic Resonance Center) of Bicêtre Hospital. The authors describe their technique for the exploration on the cord in case of suspected intramedullary cavitation, and emphasize the morphological and evolutive aspects of these abnormalities, whether they have been operated or not.

Adolescent↗
PubMed1991

Anterior and posterior hypopituitarism with pituitary stalk abnormalities.

Hypopituitarism and diabetes insipidus are often idiopathic conditions. A retrospective study of 6 cases of diabetes insipidus and 8 cases of partial or global idiopathic anterior hypopituitarism has shown that MRI is of considerable value to detect abnormalities of the pituitary stalk or hypothalamo-pituitary "relay". On the basis of MRI findings, some cases of idiopathic hypopituitarism can now be grouped together in a new entity which may be called hypopituitarism due to neonatal transection of the pituitary stalk.

Adolescent↗
PubMed1991

[The normal cranial nerves in MRI. Description and visualization frequency].

In order to assess the value of MR in the depiction of intracranial nerves, we retrospectively reviewed 60 patients investigated over a period of 2 years. The aim of this study was: 1) to assess the score of MR in the detection of cranial nerves III to XII; 2) to determine accurate landmarks allowing for easy detection of those cranial nerves. Cranial nerves III, V, VII, VIII are well seen (70 to 100%), very often in both axial, sagittal and coronal sections. Nerves IX to XII are correctly studied only on axial planes [81 and 83%), but it is difficult to distinguish between the vagal nerve and the glossopharyngeal and spinal nerves. Due to their oblique direction and small size, fourth and sixth nerves are rarely visualized. The more important landmarks are the chiasma, the colliculi, the Meckel's cave, the internal auditory canal, the jugular foramen, the hypoglossal canal and the different brainstem structures. We suggest the following scanning protocol: short spin echo sequences (TR = 600 ms, TE = 20 msec), 3 to 5 continuous sections, 16 to 20 cm field of vue with respectively 4 or 2 excitations, 256 x 256 matrix, with at least one acquisition plane (axial), but preferably two or three planes. Thus MR is sensitive exam in the recognition of cranial nerves, and it must be the first step exam in patients presenting with cranial nerve disease.

Adult↗
PubMed1990

Occult cerebrovascular malformations: follow-up with MR imaging.

The clinical and magnetic resonance (MR) imaging findings in 20 patients with MR evidence of occult cerebrovascular malformations (OCVMs) were retrospectively analyzed. Of 27 lesions followed up throughout a mean period of 18 months, eight showed obvious evolution on MR images (four cases of regression and four cases of new bleeding). Three new independent lesions were disclosed. Clinical evolution was discordant with MR findings in five patients. In the other patients, topography of the lesion, mass effect, and location of the hemorrhage could explain clinical data. The dynamic nature of OCVMs must be considered in decisions on therapeutic management.

Adult↗
PubMed1990

Visibility of cranial nerves at MRI.

In order to assess the value of MRI in the depiction of intracranial nerves, we retrospectively reviewed 60 patients investigated over a 2-year period. The purposes of this study were: 1) to determine the score of MRI in detecting cranial nerves III to XII, and 2) to establish accurate landmarks for easy detection of these nerves. Cranial nerves III, V, VII and VIII are well seen (70 to 100%), very often on axial, sagittal and coronal sections. Nerves IX to XII are correctly studied only on axial planes (81 and 83%), but it is difficult to distinguish between the vagus nerve and the glossopharyngeal and spinal nerves. Due to their oblique direction and small size, nerves IV and VI are seldom visualized. The most important landmarks are the chiasma, the colliculi, Meckel's cavity, the internal auditory canal, the jugular foramen, the hypoglossal canal and the brainstem structures. We suggest the following scanning technique: short spin-echo sequences (TR 600 ms, TE 20 ms), 3 to 5 mm thick contiguous sections, 16 to 20 cm field of view with 4 or 2 excitations respectively, 256 x 256 matrix, and at least one acquisition plane (axial plane), but preferably two or three planes. MRI is a sensitive examination in the recognition of cranial nerves. It should be the first-step exploratory procedure in patients with cranial nerve pathology.

Adolescent↗
PubMed1990

[Late solitary and benign neurilemmoma of the pterygo-maxillary region].

The neurilemmoma of the pterygoid fossa are very rare. The authors reports one case of a 32 years old man, with such a neoplasm, exteriorized on the lateral facial region (area of the glandula parotis) clinical and radiological data could not differentiate benign neurilemmoma or slow evolutive sarcoma and have justified a conservative latero facial approach of the neoplasm. The final diagnosis of ancient neurilemmoma was based on both light and electron microscopy morphology.

Adult↗
PubMed1990

[Upper cervical intradural lipoma. Apropos of a case].

Intradural lipoma is a rare and slow growing tumor which represents 1% of all intra-spinal tumors. This tumor is often associated with dysraphism. It can be isolated without any associated vertebral or cutaneous malformations. Its clinical evolution is extremely slow and progressive. The fatty composition of this type of tumor allows easy detection by CT as well as by MRI. MRI permits: Reliable and direct assessment (in 3 different plans) of the extension of the lesion. An excellent post operative control.

Cervical Vertebrae↗
PubMed1989

[Diagnosis of diseases of the spinal cord and the vertebral column].

Magnetic resonance imaging (MRI) nowadays plays a predominant role in the diagnosis and evaluation of spinal canal pathologies and has reduced the other exploratory methods, including computerized tomography (CT) and myelography, to an ancillary role. These pathologies are divided into three groups: those where MRI is the only imaging method (syringomyelia, tumours in the spinal canal, phakomatoses, external pachymeningitis, spinal cord injuries, myelitis); those where MRI is the initial method and is completed by other examinations (vascular malformations, dysraphism, myelopathies due to cervical osteoarthritis) and those where MRI still play a lesser role than CT (degenerative lesions of the lumbar column).

Humans↗
PubMed1989

Magnetic resonance investigations of non-acoustic petrous lesions.

Twenty cases of intrapetrous lesions were studied by a 1.5 T magnetic resonance (MR) unit. In all cases, comparisons were made between MR, CT and clinical findings. Our present material included 9 cholesteatomas, 1 cholesterol cyst, 3 primary epidermoid carcinomas, 2 metastatic neoplasms, 1 glomus jugulare tumor and 4 facial neurinomas. Gadolinium was injected in 7 cases and seemed to be the best method for studying the intrapetrous tumors. MR permitted accurate topographic study and assessment of tumoral extension, as well as a ready demonstration of tumor vascularity. The present findings also showed that MR is not capable of defining small bony detail or calcifications.

Adolescent↗
PubMed1989

[MRI in the diagnosis of recurrent cholesteatoma of the petrous bone].

Nine cases of recurrent petrous cholesteatomas have been studied by a 1,5 T MR unit. Gadolinium was injected in 1 case. In all cases, comparison between MR, CT and clinical findings were made. MR allows for accurate topographic study and assessment of cholesteatomas extension, in particular in the posterior fossa and skull base. Relationships with the internal carotid artery and the jugular vein are clearly depicted.

Adult↗