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Biomedical subjects

M F Mafee

Publications and source records attributed to M F Mafee.

At least 19 recordsLinked to original sources
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↗
PubMed1995

Applications of MR angiography in head and neck pathology.

MR angiography is a useful examination in the area of head and neck pathology when correctly applied and tailored to a specific clinical problem. Of the cases presented in this article, the most common application is evaluation of vascular invasion or displacement to aid in surgical planning of tumor resection. Applications to evaluation of vascular thrombosis or dissection, assessment of tumor vascularity, and visualization of variant vascular anatomy and acquired vascular disease were also demonstrated.

Adolescent↗
PubMed1995

MR imaging of squamous cell carcinoma of the larynx and hypopharynx.

Despite recent diagnostic advances, the laryngopharynx remains an area where accurate assessment of tumor size and extent is difficult. Computed tomography has proven helpful in delineating lesions in these areas, yet significant limitations exist. In an attempt to more accurately evaluate laryngopharyngeal neoplasms, MR imaging was performed in 25 consecutive patients with squamous cell carcinoma of the larynx and hypopharynx. Mr imaging was analyzed for its utility in clinical staging, assistance in selection of candidates for conservation, Laryngeal surgery, and ability to reliably predict cartilage invasion. MR imaging improved the accuracy of tumor staging by 40% and was valuable in the selection of candidates for conservation surgery. In addition, MR imaging was able to predict cartilage invasion in 6 of 6 patients with pathologic confirmation with a single false-positive case. MR imaging appears to be a reliable indicator of tumor size and location and should be judiciously incorporated into the staging and pretreatment planning of patients presenting with laryngopharyngeal malignancies.

Carcinoma, Squamous Cell↗
PubMed1994

Differential diagnosis of leukokoria: radiologic-pathologic correlation.

Leukokoria is an abnormal pupillary light reflection that usually results from an intraocular abnormality and is seen most often in children. One-half of the cases of childhood leukokoria are caused by retinoblastoma, a malignant tumor of immature retinoblasts that manifests in a normal-sized eye as a calcified mass, is often partially necrotic, and grows into the vitreous and through the choroid. Retinoblastoma enhances with contrast material and, unlike most tumors, may be darker than vitreous on T2-weighted images. When leukokoria is associated with microphthalmia, persistent hyperplastic primary vitreous (PHPV) (28% of cases) or retinopathy of prematurity (ROP) (5% of cases) should be considered. PHPV is a congenital, usually unilateral lesion that appears as a dense tubular mass extending from the lens to the retina along the course of the hyaloid canal. Hemorrhage from PHPV produces a subhyaloid (or subretinal) fluid collection, often with characteristic blood-fluid levels. ROP is bilateral and usually manifests in premature infants who received supplemental oxygen therapy. Coats disease (16% of leukokoria) is a sporadic unilateral idiopathic retinal telangiectasia that produces a lipoproteinaceous subretinal exudate leading to complete retinal detachment. The globe has normal size but increased attenuation and signal intensity from hemorrhage without calcification or enhancement. Toxocaral endophthalmitis (16% of leukokoria) is a granulomatous reaction to the parasite in the vitreous and uveoretinal coat. Retinal astrocytoma (3% of leukokoria), which manifests in a normal-sized globe, is an indolent benign neoplasm commonly associated with phakomatoses (usually tuberous sclerosis).

Child↗
PubMed1994

Epidermoid cyst (cholesteatoma) and cholesterol granuloma of the temporal bone and epidermoid cysts affecting the brain.

Five cases of petrous apex epidermoid cysts, six cases of petrous apex cholesterol granuloma cysts, and seven cases of intradural cerebellopontine angle (CPA) or intracranial epidermoid cysts are reviewed. Petrous epidermoid cysts (cholesteatomas) and cholesterol granuloma cysts cannot be differentiated definitely from each other on CT scans. On MR imaging, epidermoid cysts exhibit long T1 and long T2 characteristics and can be differentiated from cholesterol granuloma cysts, which exhibit short T1 and long T2 characteristics. Intradural epidermoid cysts involving the CPA or other portions of the brain, also demonstrate long T1 and long T2 characteristics on MR scans. Intradural epidermoid cysts exhibit curvilinear areas of higher intensity on T1-weighted images, which were best evaluated on T1-weighted MR images obtained with more averages (6 to 8).

Adolescent↗
PubMed1994

Modern imaging of paranasal sinuses and the role of limited sinus computerized tomography; considerations of time, cost and radiation.

The modern diagnostic radiology department is equipped with a variety of medical imaging systems that can be used for evaluation of diseases of the sinonasal cavities. Each has advantages and disadvantages. The imaging examinations of the paranasal sinuses may include conventional films, complex motion tomography, computed tomography (CT) and magnetic resonance imaging (MRI). The indications for these imaging methods are reviewed, along with a discussion on the role of imaging for endoscopic sinus surgery. A summary of CT anatomy relating to the ethmoidal sinuses and ostiomeatal complex is given, as is a review of the risk of radiation for radiologic sinus imaging.

Carcinoma↗
PubMed1994

Orbital and optic pathway sarcoidosis: MR findings.

PURPOSE: To identify and characterize the MR findings of sarcoidosis when it involves the orbit and visual pathways. METHODS: The MR scans of 15 patients, 3 with presumed and 12 with proved orbital or optic pathway sarcoidosis were retrospectively reviewed. RESULTS: Eight patients had MR evidence of optic nerve involvement by sarcoid granuloma. Perineural enhancement was seen in four cases, optic atrophy in one. Three who had had unenhanced scans showed optic nerve enlargement. Nine patients had optic chiasmal involvement. One patient had increased T2 signal in the optic radiations. Three patients had orbital masses that had MR signal characteristics similar to pseudotumor. Five patients had periventricular white matter abnormalities closely resembling multiple sclerosis. CONCLUSIONS: Sarcoidosis should be considered in the differential diagnosis of optic nerve or nerve sheath enhancement on MR. Orbital sarcoidosis has MR characteristics very similar to pseudotumor.

Adolescent↗
PubMed1993

MRI and CT in the evaluation of acquired and congenital cholesteatomas of the temporal bone.

Acquired (secondary) cholesteatomas of the middle ear and mastoid are usually a complication of chronic otomastoiditis and are often accompanied by infection from the outset, and their contents show evidence of some inflammatory reaction. Congenital (primary) cholesteatomas of the temporal bone are due to epithelial rest of embryonal origin. There are many sites of occurrence of congenital cholesteatomas (epidermoids) within the temporal bone: (1) middle ear, (2) mastoid, (3) middle ear and mastoid, (4) petrous bone, (5) the squama, and (6) within the tympanic membrane. Intradural (cisternal) congenital cholesteatomas are another type of cholesteatomas that often involve the cerebellopontine angle (CPA) region and cause varying degrees of cochlear and vestibular symptoms and signs. In this paper, we stress the role of magnetic resonance imaging (MRI) and computed tomography (CT) in the evaluation of acquired and congenital cholesteatomas of the temporal bone. It is our opinion that CT remains the study of choice for cholesteatomas of the middle ear cleft. MRI is superior to CT for the evaluations of infected cholesteatomas, petrous apex, and CPA cholesteatomas, as well as for the majority evaluation of cholesteatomatous involvement of the facial nerve, membranous labyrinth, and intracranial structures.

Bone Diseases↗
PubMed1993

Preoperative imaging anatomy of nasal-ethmoid complex for functional endoscopic sinus surgery.

Endoscopic sinus surgery has become an increasingly popular surgical procedure. Functional endoscopic sinus surgery is based on the hypothesis that the ostiomeatal complex is the key area in the pathogenesis of chronic sinusitis. This article discusses the concept of functional endoscopic sinus surgery, the anatomy of the ostiomeatal complex, and the imaging anatomy of the ostiomeatal complex.

Endoscopy↗