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Biomedical subjects

M F Mafee

Publications and source records attributed to M F Mafee.

At least 37 records · Page 2Linked to original sources
PubMed1998

Retinoblastoma and simulating lesions. Role of CT, MR imaging and use of Gd-DTPA contrast enhancement.

The diagnosis of Rb can usually be made by clinical examination; however, patients should also be studied by CT and MR imaging to help determine the extent of the intraocular tumor, document intralesional calcification, confirm the diagnosis, and delineate orbital or intracranial involvement. These imaging techniques should aid the clinician in differentiating Rb from lesions that simulate Rb.

Brain Neoplasms↗
PubMed1998

Coats' disease and persistent hyperplastic primary vitreous. Role of MR imaging and CT.

Coats' disease is an idiopathic disorder in which telangiectatic and aneurysmal retinal vessels leak a lipoproteinaceous exudate, with consequent bullous retinal detachment. It is a diagnostic challenge, and CT and MR imaging provide valuable information to differentiate it from other pathologies, particularly from retinoblastoma. Typical, advanced Coats' disease shows on CT a denser substance posterior to the vitreous, which on MR is hyperintense on all pulse sequences. Contrast administration on both CT and MR might give slight linear enhancement at the boundary between vitreous and exudation. Persistent hyperplastic primary vitreous (PHPV) is a unilateral disorder in a microphthalmic eye, seen in full-term infants. PHPV rarely is bilateral in patients with Norrie's disease, Warburg syndrome, or patients with retinal dysplasia. Persistent fetal vasculature leads to fibrosis, resulting in elongation of the ciliary processes, retinal detachment, and spontaneous cataracts. The CT appearance in the disorder is quite variable; however, MR imaging may be superior in demonstrating the enhancing retrolental mass and the elongated ciliary processes.

Aneurysm↗
PubMed1998

Diagnostic imaging of cystic lesions in the child's orbit.

The child's orbit may be involved with a variety of cysts and cyst-like lesions. Such lesions may represent development anomalies of the globe and orbit, acquired lesions of the orbit, or cystic expansions from contiguous structures. CT and MR imaging are important diagnostic tools that aid the ophthalmologist in establishing the correct diagnosis and defining the extent of these cystic lesions.

Child↗
PubMed1998

MR imaging and CT of orbital infections and complications in acute rhinosinusitis.

The acute onset of orbital and periorbital inflammation presents the clinician with a diagnostic and therapeutic dilemma, the consequence of which may be very serious. The progression from the initial stage of cellulitis to orbital abscess, cavernous sinus thrombosis, brain abscess, meningitis, or visual loss may be quite rapid at times. CT, ultrasonography, and MR imaging play an important role in clinical management of these patients. Indeed, it is the information obtained through orbital imaging that directs the clinician to use the correct therapeutic modality.

Abscess↗
PubMed1998

Orbital subperiosteal hematoma, cholesterol granuloma, and infection. Evaluation with MR imaging and CT.

Orbital subperiosteal space, a potential space, is an important entity due to its unique anatomy and susceptibility to various pathologic processes. CT scan and MR imaging are important tools in the diagnosis of orbital subperiosteal hematomas, cholesterol granulomas, and infections. MR imaging has emerged as the modality of choice in the evaluation of hematomas and infections of this space due to its multiplanar capability and various imaging sequences giving better information. High-resolution CT scan offers good differentiation in most of these cases. Osseous changes in a cholesterol granuloma is better seen in CT scan, although MR imaging offers better differentiation from epidermoid or dermoid cysts and other subperiosteal process, as well as lacrimal fossa lesions. Subperiosteal abscesses are best evaluated using MR imaging.

Abscess↗
PubMed1998

Rhabdomyosarcoma of the orbit. Evaluation with MR imaging and CT.

Rhabdomyosarcoma is the most common primary orbital malignancy of childhood. It can present insidiously, mimicking other (benign) processes clinically and radiographically. CT and MR imaging are crucial in the diagnostic evaluation, treatment planning, and follow-up monitoring of the disease. Such imaging, especially when contrast is used, can accurately detect and state the extent of tumor involvement.

Adolescent↗
PubMed1998

Langerhans' cell histiocytosis and juvenile xanthogranuloma of the orbit. Clinicopathologic, CT, and MR imaging features.

The clinical, radiologic, and histopathologic features of two main disorders of the orbit are discussed. Group I, Langerhans cell histiocytosis (histiocytosis X, Class I), is caused by proliferation of X histiocytic Langerhans' cells. Group II is juvenile xanthogranuloma, and Class II is related to the proliferation of non-X histiocytic (monocyte-macrophage) cells. The two diseases are of unknown cause and differ in their clinical, radiologic, and histopathologic features.

Cell Division↗
PubMed1998

Fibro-osseous, osseous, and cartilaginous lesions of the orbit and paraorbital region. Correlative clinicopathologic and radiographic features, including the diagnostic role of CT and MR imaging.

Fibro-osseous and cartilaginous lesions of the orbit and facial region share overlapping clinical, radiologic, and pathologic features that may lead to diagnostic confusion and possible misdiagnosis. The value of imaging studies in the histopathologic diagnosis of these lesions cannot be overemphasized. The histopathologic diagnosis of such lesions should not be rendered in the absence of radiographic correlation.

Cartilage Diseases↗
PubMed1998

Third ventriculostomy, phase-contrast cine MRI and endoscopic techniques.

Endoscopic third ventriculostomy has become an increasingly popular procedure. This is mainly due to the improvement of the endoscopes. The progress in imaging techniques and Phase-Contrast Cine MRI in particular offers a reliable method of pre-and post-operative assessment of the patients. Two endoscopes, NeuroPEN and Channel Neuroendoscope (Medtronic PS Medical, CA, USA) have been evaluated in our center for third ventriculostomy. These instruments are light, have a good maneuverability and are disposable. The illumination and the quality of the image are excellent. We have performed Phase-Contrast Cine MRI pre-operatively and post-operatively for our patients. It offers a good assessment of the patency of the ventriculostomy and the fluid dynamics of the CSF pathways. Endoscopic third ventriculostomy is the technique of choice for the treatment of obstructive hydrocephalus. This is mainly due to two points: The progress in the endoscopic instrumentation (namely the reduction in size of endoscopes and introduction of disposable models), and the establishment of Phase-Contrast Cine MRI as the gold standard method for the pre- and post-operative evaluation of the CSF dynamics. However, to date, no technique can show the patency of the subarachnoid space, which is the most important predictive factor of surgical outcome.

Endoscopy↗
PubMed1997

MRI of mesenchymal chondrosarcoma of the orbit: case report and review of the literature.

Extraskeletal mesenchymal chondrosarcoma is a relatively uncommon entity, an orbital location being extremely rare. A review of the literature revealed 16 reported cases of primary orbital mesenchymal chondrosarcoma demonstrated by plain film and CT. To the best of our knowledge, the MRI features of orbital extraskeletal mesenchymal chondrosarcoma have not been previously reported. We present the case of an 18-year-old man with a 2-year history of progressive proptosis of the right eye who underwent CT, dynamic CT, MRI without and with gadolinium enhancement, and magnetic resonance angiography of the orbits. CT of orbital mesenchymal chondrosarcoma demonstrates a well-defined mass with multiple areas of fine and coarse calcification and shows moderate contrast enhancement. The noncalcified portions of the mass demonstrate signal intensity lower than or equal to gray matter on T1-weighted images and are isointense to the gray matter on T2-weighted images. Dynamic CT reveals delayed contrast enhancement. MRI has proven to be a valuable diagnostic tool in the diagnosis and differentiation of well-defined intraorbital masses. By a combination of CT and MRI, it appears mesenchymal chondrosarcoma can be differentiated from other intraorbital lesions, such as cavernous hemangioma, hemangiopericytoma, orbital amyloidosis and fibrous histiocytoma.

Adolescent↗
PubMed1996

Gadolinium enhancement: improved MRI detection of retinoblastoma extension into the optic nerve.

We performed T1-, T2-, proton density-weighted, and T1-weighted gadolinium-enhanced MRI on 24 patients with retinoblastoma, using a 1.5 T superconducting unit and head and orbital surface coil imaging. All patients underwent a complete ophthalmologic examination, including B-scan ultrasonography. CT was performed on 10 of 24 patients. Pathologic correlation was obtained in 18 patients who required enucleation. Contrast-enhanced T1-weighted MRI with fat suppression was the sequence most sensitive to optic nerve extension and provided the greatest differentiation between tumor and uninvolved extrascleral tissue. Retinoblastoma demonstrated contrast enhancement.

Child↗
PubMed1996

Ocular and orbital imaging.

The development of magnetic resonance imaging technology has proven to be a great breakthrough in diagnostic medical imaging, ophthalmologic imaging, and biomedical research. The anatomic detail demonstrated by an magnetic resonance image is a representation of at least three physical properties of static tissue: photon density and T1 and T2 relaxation times. Intrinsic differences in proton density and proton relaxation times of tissues allow excellent image contrast between various normal structures and high sensitivity for detecting pathologic states. This article discusses magnetic resonance imaging features of common ocular and orbital lesions, with emphasis on the potential of magnetic resonance imaging in ophthalmology.

Eye↗
PubMed1996

Magnetic resonance imaging findings in a case of advanced Coats' disease.

Coats' disease is an idiopathic, primary vascular anomaly of the retina often presenting with retinal detachment. In this report, the unusual radiologic findings of a 17-month-old patient with advanced Coats' disease are discussed. Computed tomography (CT) showed diffuse increased density of the right eye. Magnetic resonance imaging (MRI) demonstrated moderately hyperintense signal intensity on T1-weighted images, mildly hypointense signal intensity on T2-weighted images, and linear enhancement of the leaves of the detached retina with intense enhancement in the retinal periphery following gadolinium-diethylenetriamine penta-acetic acid (DTPA) contrast administration. The hypointense T2-weighted images and the linear enhancement of the detached retina have not been reported previously in cases of Coats' disease. These observations correlated with the histopathologic features, which showed a totally detached retina containing large telangiectatic vesses and a supretinal space occupied by eoinophilic proteinaceous exudates containing abundant cholesterol crystals. It appears that the MRI characteristics observed in Coats' disease may vary depending on the nature of the subretinal exudate and the severity of the disease.

Eye Enucleation↗
PubMed1996

The eye.

In recent years, the growing application of computed tomography (CT) and magnetic resonance (MR) imaging evaluation of the orbit and globe have dramatically increased the role of imaging and, hence, that of the radiologist in assessing ophthalmologic disorders. This article discusses magnetic resonance imaging features of the most common and less common ocular pathologies, with particular emphasis on the potential of magnetic resonance imaging in the field of ophthalmology.

Diagnosis, Differential↗
PubMed1995

'Morphing' class filter: an interactive tool for continuous adjustment of tissue type related contrast.

The proposed class filter increases tissue type related contrast in MR images of brain. During the first phase of the filtering process tissue type classes are defined. This is done by operator intervention, or by a semiautomatic process based either on a supervised or unsupervised classifier, respectively. During the second phase a pixel intensity transform makes pixels of the same tissue class appear 'more similar' while the pixel intensities of different classes will become 'more different', in effect increasing the tissue type related contrast. For example, normal mixture cluster analysis is performed on an MR image set obtained by varying pulse sequence (PS) parameters and provides unsupervised definition of classes while taking advantage of much greater information content of the whole image set in comparison to that of a single image. The algorithm permits continuous transition ('morphing') between the original image and the tissue classification image that has been calculated from the input image set by simple sliding cursor-bar on the computer screen under the physician's control. Consequently, the resulting images do not require retraining of the physician who is already familiar with the appearance of standard MR images and they make mental integration of information from a large input image set possible and easier.

Brain↗
PubMed1995

MR imaging of intralabyrinthine schwannoma, labyrinthitis, and other labyrinthine pathology.

This article reviews recent imaging developments in various diseases of the membranous labyrinth. Membranous labyrinth is the initial receptor for acoustic stimuli. Exciting progress has been made in the imaging evaluation of the normal and diseased labyrinth. Structures of the membranous labyrinth, such as the cochlea, vestibule, semicircular canals, and endolymphatic duct and sac can be visualized on routine MR scans. Using high-resolution MR imaging techniques, researches have been able to visualize the cochlear duct, scala tympani, scala vestibuli, and even the otolithic mass. The sensitivity of gadolinium-enhanced MR imaging is such that labyrinthitis or other labyrinthine pathology, including small intralabyrinthine schwannomas, can be diagnosed on routine MR study.

Ear Neoplasms↗