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D Doyon

Publications and source records attributed to D Doyon.

At least 19 recordsLinked to original sources
PubMed2003

[MRI in the diagnosis of Rathke's cleft cyst].

PURPOSE: Rathke's cleft cysts are non neoplastic lesions of the sellar area that seldom are symptomatic. Their incidence has been underestimated before magnetic resonance imaging (MRI). The aim of this work was to assess the value of MRI in the diagnosis and differential diagnosis of Rathke's cleft cyst based on a retrospective review of 12 cases and a review of the literature. PATIENTS AND METHODS: We retrospectively reviewed the MRI features of 12 patients with Rathke's cleft cyst collected over 4.5 years. Patients included ten females and two males (mean age: 39 years). The most common presentation was the association of dysmenorrhea and pituitary dysfunction. MRI examinations were performed using a 1.5 Tesla system, T1 and T2 weighted sequences performed before and after Gd- DTPA injection. Signal intensity, shape, size and location of the lesion were analyzed. RESULTS: In all cases, MRI examination showed a cystic lesion of variable size and signal intensity. The cyst was purely intrasellar in nine cases and a suprasellar extension was noted in three cases. Five patients underwent surgery providing pathological confirmation, four underwent routine follow-up and three were lost of follow-up. CONCLUSION: We conclude that MRI is an efficient tool for diagnosis, allowing appropriate medical decision making.

Adolescent↗
PubMed2002

[MRI sequences in the detection of cavernous angiomas].

We prospectively evaluated 30 patients with CNS cavernous angioma with a high field (1.5T) magnetic resonance imager. In all patients the MRI protocol included: gradient echo T1*-weighted imaging, spin echo T2*-weighted imaging and gradient echo T2*-weighted imaging. We evaluated each case for the number of lesions detected on each sequence. Gradient echo T2*-weighted imaging with a long TE (TE: 35ms) was the most sensitive sequence for the detection of cavernous angiomas allowing detection of small lesions that were not identified on the other sequences.

Central Nervous System Neoplasms↗
PubMed2001

Hemangioma of the porus acusticus. Impact of imaging studies: case reports.

Hemangiomas are tumors. Hemangiomas near the geniculate ganglion or in the internal acoustic meatus are well known but rare. We present two cases of hemangiomas located at the porus acusticus, an even more rare site. MRI showed a millimeter-sized tumor, located in the porus acusticus, developing perpendicular to the axis of the acoustico-facial nerves, surrounding them. They were hyperintense on T1-weighted images, strongly hyperintense on T2-weighted images with a characteristic progressive and marked enhancement after injection of gadolinium DTPA. Similar signal abnormalities were present in the adjacent temporal bone, and CT scan demonstrated a honeycomb appearance with intratumoral bony spicules. These imaging criteria allows differentiation between hemangioma and neurinoma. We hypothesize that this location is related to the presence of a rich vascular plexus of the dura mater in this area.

Adult↗
PubMed2001

Normal pituitary hypertrophy as a frequent cause of pituitary incidentaloma: a follow-up study.

Enlargement of the pituitary gland is a frequent cause of incidentaloma and of referrals to endocrinologists for hormonal evaluation and therapeutic advice. In neuroradiological series, 25-50% of healthy women who are 18-35 yr old have a convex superior pituitary contour, but pituitary height exceeds 9 mm in less than 0.5% of cases. This study was performed to provide thorough clinical and hormonal data and long-term endocrinological and imaging follow-up data on subjects with incidentally discovered pituitary hypertrophy (height > 9 mm). Seven eugonadal nulliparous women, 15-27 yr old, referred between 1989 and 1998 with incidentally diagnosed pituitary gland enlargement (height > 9 mm) and a suspected pituitary tumor, were studied. At presentation and at yearly intervals, PRL plasma levels and corticotropic, somatotropic, and thyrotropic pituitary function were measured; and pituitary dimensions and signal on magnetic resonance imaging (MRI), before and after iv gadolinium-diethylene-triamine-pentaacetic acid injection, were assessed. PRL plasma levels were normal; and corticotropic, somatotropic, and thyrotropic pituitary function was considered normal in all cases. In all the women, the upper boundary of the pituitary was convex, on MRI, and touched the optic chiasm in four cases. The width and anteroposterior diameter of the gland were normal. The pituitary itself seemed normal, with a homogeneous signal, on plain and dynamic studies with iv contrast injection. Despite normal initial hormone values, two women underwent surgery, by the transsphenoidal approach, in another center. During surgery, the pituitary seemed normal in both cases, with no evidence of tumoral or inflammatory processes. Biopsy specimens showed the morphologic characteristics of a normal, nonhyperplastic pituitary gland. All seven women were seen at yearly intervals for 2-8 yr (median, 4 yr). Clinical and hormonal status remained stable, as did the structure and size of pituitary, on serial MRI. No tumor formation occurred, supporting the diagnosis of physiologic hypertrophy of the pituitary gland. In conclusion, these observations suggest that careful examination of MRI results may help to distinguish physiologic pituitary hypertrophy from pituitary tumors and infiltrating lesions. The former diagnosis is confirmed by normal baseline pituitary function in extensive hormonal tests. Correct identification of such patients is important to avoid unnecessary pituitary surgery and costly MRI surveillance.

Adenoma↗
PubMed2001

[Imaging of syringomyelia].

This review reports the value of current imaging techniques in the diagnosis of syringomyelia excluding tumoral causes. The value of imaging techniques for evaluation of extension, detection of associated anomalies, and pre- and postoperative evaluation are detailed.

Humans↗
PubMed2001

[Artifacts induced by dental reconstruction materials: the case of titanium].

MRI is becoming an important tool of examination of the head and neck. However, certain dental alloys cause artifacts characterized by a loss of signal surrounded by bright line and sometimes distortions. In our work, we studied artifacts caused by Titanium, metallic biomaterial used for oral implantology. Therefore, 2 experimental were investigated in a 1.5 T MR unit, with 2 sequences commonly used (SE, GRE). The investigation showed minor artefacts, without distortions. In order to minimize these "ghost images", the Titanium and its alloys should be an alternative.

Alloys↗
PubMed2000

Visibility of the central canal on MRI.

The central canal of the spinal cord is present at birth and becomes progressively obliterated. Cadaver studies have shown that it may persist partially or completely. To our knowledge, this entity has not been described on MRI. We reviewed 794 MRI studies of the spinal cord, and found 12 patients (aged 14 to 65 years) who had an intramedullary cavity. The cavity was at the junction of the ventral 1/3 and dorsal 2/3 of the spinal cord, except at the level of the lumbar enlargement, where it was central. It was filiform in most cases, although sometimes fusiform (3 to 4 mm in diameter), and had regular contours. The cavity were thoracic in 69 % of cases. The clinical features were totally unrelated to the image, and there were no anatomical factors (Chiari malformation, dysraphism) predisposing to syringomyelia. The images were perfectly compatible with a persistent central canal, which we interpret as a variant of normal anatomy. Therefore it is important to regard these findings as normal, to avoid unnecessary treatment and follow-up.

Adolescent↗
PubMed1999

[The place of MRI in the study of cerebrospinal fluid fistulas].

Results of CT and MRI explorations in 8 patients with cerebrospinal fluid (CSF) fistulae are reported and compared with surgical findings in 7. Sensitivity of MRI (CISS and fast T2 spin-echo sequences) was excellent giving perfect correlations with surgical findings in 7/7 cases. CT and MRI were found to provide complementary information suggesting they should be used in combination as first intention explorations of suspected CSF fistulae. Computerized cisternography should be used if MRI is contraindicated or if a clinically and biologically proven CSF fistulae is not visualized by CT or MRI.

Adolescent↗
PubMed1999

[Imaging of syringomyelia].

MRI is the best imaging method to evaluate syringomyelia. It is important to study from the posterior cranial fossa to the sacro-lumbar region and also the supra-tentorial structures. This complete analysis is essential to classify the syringomyelia and to investigate other associated malformations. Radiographs and CT scan are useful to analyze bone structures. For MRI, the new sequences with phased-array coils are also very important to study the entire spinal cord and the posterior fossa. It is essential to study the spinal cord with sagittal and axial spin echo T1 and fast spin echo T2 weighted images with sometimes coronal view, particularly when the patient presents a scoliosis, to have a correct morphological and functional evaluation. MRI gives an excellent study of the spinal cord with an excellent analysis of a primitive or foraminal syringomyelia, but also traumatic, infectious or post arachnoiditis syringomyelia. Spin echo T1 weighted images with injection of gadolinium can be used if an intra-medullary tumor is suspected. MRI is also useful for the post-operative follow up to evaluate the persistence of the medullary cyst and the enlargement of the foramen magnum.

Brain↗
PubMed1999

[Neurocysticercosis].

The neurocysticercosis is an infestation of the central nervous system by larvae of Taenia solium. The disease is endemic in a few countries of Latin America, Asia, and Africa and is becoming increasingly prevalent in the United States and Europe. The immigration of individuals from endemic areas and the tourism in these areas require a good knowledge of this disease. A retrospective study evaluating the neurocysticercosis lesions with MR and CT is proposed. Parenchymal, subarachnoid and intraventricular cysts are evaluated. We were able to recognise four CT and MR stages. MR was useful in detecting the cysts of neurocycticercosis in the first stage but was inferior in the detection of parenchymal calcifications.

Animals↗
PubMed1998

Anomalous vessel in the middle ear: the role of CT and MR angiography.

An 8-year-old child was examined because of conductive hearing loss with a retrotympanic mass on otoscopy. CT and MR angiography showed a large inferior tympanic artery traversing the hypotympanum and joining a thin, irregular internal carotid artery with a normal middle meningeal artery. These investigations, coupled with knowledge of the embryological development allowed a diagnosis of a complex vascular anomaly in the middle ear and avoided potential surgical complications.

Carotid Artery, Internal↗
PubMed1998

[Magnetic resonance study of the pineal region. Normal pineal gland and simple cysts].

A magnetic resonance imaging (MRI) study of the normal pineal gland and pineal simple cysts was performed in 762 cases. A fine section technique (maximum 3 millimeters) enabled most of the times the identifying of a normal pineal in addition to demonstrating that a pineal without any cyst shows an isointense signal in T1 and T2 which, in turn, is enhanced following gadolinium. The measure of the normal pineal was of about 6.1 millimeters in its diameter length. Pineal simple cysts were observed in a 2.6% frequency in relation to the whole series (762 cases); however reaches 6.1% when only the visualized pineals were considered (329 cases). Also, it was found out that simple cysts were not correlated to age or gender. Simple cysts characteristics are: dimension less or equal to 20 millimeters; absence of expansive effect; similar signal to that of the cerebrospinal fluid; absence of cyst growth.

Adolescent↗
PubMed1998

[XII cranial nerve pseudoneurinoma due to spontaneous fibrous transformation of an aneurysm of the vertebral artery].

The authors report an exceptional case report of tumor like evolution of a completely thrombosed aneurysm of the right vertebral artery suggestive of neurinoma of the XII nerve. We describe CT, MRI, MR-angiography. The diagnosis has been established by pathologic study after surgical extraction. Our case demonstrate the possibility of growth of totally thrombosed aneurysms and we discuss various mechanisms.

Aged↗
PubMed1998

[MRI symptomatology of non-tumoral myelopathies].

We present a retrospective study in order to analyze the abnormalities noted on MRI in 27 cases of myelopathy excluding tumors, explored between 1994 and 1996. The different lesions were: Multiple Sclerosis (n = 11), Spondylotic myelopathy (n = 3), Neurosarcoidosis (n = 4), CMV Myelitis (n = 1), Radiation Myelopathy (n = 1), Spinal Dural Arteriovenous Fistula (n = 1), Intramedullary Cysticercosis (n = 1), Infarct (n = 5). The exams have been made on 1.5 Tesla Magnetom Vision Siemens or GE Signa machine. All patients have had axial and sagittal views with coronal complementary study in 4 cases. Sequences were Spin echo pT1 (TR: 560, TE: 12), Fast Spin echo pT2 (TR: 3 500, TE: 99 or 128), and gradient echo pT2 (TR: 700, TE: 22, Angle: 25 degrees). Intravenous injection of Gadolinium has been made in 16 cases (0.1 mmol/kg). We have studied the presence or not of a signal abnormality in pT1 and/or in pT2, of enhancement, and its topography (cervical, thoracic, lumbar). We classified lesions in central and/or peripheral and according, to their topography in anterior, posterior or lateral type. The form has been classified in four types (nodular, triangular, "pen like", plage). Extension in transversal (superior or inferior to half medullary surface) and cranio-caudal directions (inferior to one vertebrae, between one and two vertebrae, superior to two vertebrae) has been also classified. Others intra or perimedullar and encephalic abnormalities have been noted. We analyzed the results for each pathology and underline the essential diagnosis criteria noted (low cranio-caudal and transversal extension with frequent triangular form of Multiple Sclerosis lesions, frequent suggestive abnormalities of the encephale (82%) in Multiple Sclerosis, intra and perimedullar enhancement with deformations of the surface of the spinal cord in Sarcoidosis' lesions, extended dorsolumbar "pen like" lesions with inconstant enhancement of infarcts, focal plage lesions centered on degenerative changes of the spinal canal in spondylotic myelopathy, bony lipomatous involution in front of intramedullary radiation plage lesion...) and also review the literature and confront their results to it. We insist on the difficulties in classifying myelopathy (radio-clinical terminology discordances, identical signal abnormalities frequently caused by different illness, necessity to compare to pathologic results). We propose a MRI study protocol that should interest the whole spinal cord and comport T1 weighted without and after gadolinium sequences, T2 weighted sequences (with always a gradient echo type). 2 or better 3 different plans should be made. A complementary study of the brain by MRI is often useful. Clinical study, biology, evolution, MRI and when possible pathology all are necessary to better understand myelopathy's mechanisms.

Adolescent↗
PubMed1998

[Imaging cranial nerves with inframillimetric T2-weighted MRI].

Fifty files were evaluated to determine the normal anatomy of the cranial nerves. All the cranial nerves were studied including the labyrinth, in different planes with a 3DFT-CISS imaging technique. The 3DFT-CISS is especially interesting to study cranial nerves because of the excellent contrast with CSF-fluid and the possibility of thin sections. It might be essential for the diagnosis of neuralgia and cranial nerves paralysis.

Cranial Nerves↗
PubMed1998

[Anatomic variants of Meckel's cave on MRI].

Magnetic resonance imaging (MRI) gives an accurate analysis of Meckel's cave variability. Images were acquired in 50 patients with several sections for anatomical comparison. Using several sections, MRI is a suitable method for better analysis of the trigeminal cistern. The most frequent findings are symmetrical trigeminal cisterns. Expansion of Meckel's cave or its disappearance has pathological significance.

Humans↗