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Biomedical subjects

A G Osborn

Publications and source records attributed to A G Osborn.

At least 37 records · Page 2Linked to original sources
PubMed1988

Disorders of histogenesis: the neurocutaneous syndromes.

MRI is uniquely suited to demonstration of the wide array of brain abnormalities in the neurocutaneous syndromes, due to its ability to provide previously unattainable neuroanatomic information on T1-weighted images and its extreme sensitivity to changes in water content of brain structures on T2-weighted images. It therefore is assisting physicians in better understanding the full expression of these heritable disorders, such as the extent of optic pathway involvement in optic nerve glioma, the presence of hamartomas in TS, and abnormal myelination in Sturge-Weber syndrome. It may in the future have a role in genetic counseling in TS. CT provides complimentary information to MRI in the evaluation of intracranial pathology in the neurocutaneous syndromes. Bone abnormalities and abnormal states of calcification may at times still be better evaluated by CT. Additionally, CT is a less expensive means of following existent abnormalities over time.

Angiomatosis↗
PubMed1987

Ranulas and their mimics: CT evaluation.

The spectrum of computed tomographic (CT) findings in ten patients with pathologically proved simple and diving ranulas is reviewed. These retention cysts originate within the sublingual space from obstruction of the sublingual or minor salivary glands; when they enlarge, the cysts herniate to involve the submandibular and inferior parapharyngeal spaces (the so-called diving or plunging ranula). CT findings in 38 additional patients with a variety of cystic lesions in the floor of the mouth are contrasted with findings in cases of ranulas. The relevant anatomy is reviewed. This experience indicates that a unilocular, cystic mass emanating from the sublingual space and extending into the adjacent submandibular and/or inferior parapharyngeal spaces can be considered a diving ranula in virtually all cases. A unilocular, cystic mass entirely within the sublingual space can be considered a simple ranula in most instances, although absolute distinction between a simple ranula and an epidermoid cyst cannot be made radiographically.

Diagnosis, Differential↗
PubMed1987

Cochlear implant candidates: assessment with CT and MR imaging.

Eighty-seven patients with severe to profound hearing loss were evaluated for possible placement of a multichannel cochlear implant hearing device. After initial clinical screening, 42 patients underwent computed tomographic (CT) examination. Five of these patients were also examined with magnetic resonance (MR) imaging. Twenty-two patients received implants. CT of the middle and inner ear was normal in 24 patients (57.1%) and showed labyrinthine ossification in 12 (28.6%), cochlear or fenestral otosclerosis (or both) in four (9.5%), and congenital cochlear malformation in two (4.8%). The information provided by CT was used to (a) exclude patients in whom multichannel cochlear implantation would most likely be unsuccessful (owing to obliterative labyrinthine ossification, or congenital cochlear malformation, severe cochlear, or fenestral otosclerosis), (b) help select the best ear for implantation, and (c) provide a preoperative picture of normal variants and avoidable surgical pitfalls. MR experience is limited but assessment of the size of the cochlear nerve and the membranous labyrinth is possible with this modality and may provide additional information in the evaluation of these patients.

Adolescent↗
PubMed1987

Vagal neuropathy: evaluation with CT and MR imaging.

The vagus nerve, as a result of its protracted course from the brain stem to the abdomen, can present a difficult imaging problem when it is compromised by a clinically occult lesion. The clinical and radiologic records of 48 patients with suspected vagus nerve dysfunction were reviewed to derive an efficient and effective approach to imaging this patient population. An imaging algorithm is proposed in which vagal neuropathies are divided both clinically and radiologically into proximal and distal categories. Proximal vagal lesions are part of a cranial neuropathy complex and have associated oropharyngeal signs and symptoms (e.g., abnormal gag reflex, uvular deviation). Distal vagal lesions occur as an isolated paralysis of the vagus nerve with no symptoms or signs referable to the oropharynx. Either computed tomography (CT) or magnetic resonance imaging can be used to diagnose proximal or distal lesions. However, CT will be insensitive in the detection of the more cephalic proximal lesions, especially those in the brain stem, basal cisterns, and skull base.

Algorithms↗
PubMed1987

CT patterns of facet fracture dislocations in the thoracolumbar region.

Thoracolumbar facets are not as commonly dislocated as are those of the cervical spine. It is, however, crucial to make an early and accurate diagnosis of thoracolumbar facet dislocation since the injury may be unstable and require reduction and internal fixation. This paper presents three major CT patterns of thoracolumbar facet fracture dislocation. The first represents anterior subluxation of the vertebral body with anteriorly locked facets. The second is a lateral vertebral body subluxation with laterally locked facets. The third is an acute kyphosis with little vertebral body subluxation but superiorly dislocated facets. Since the vertebral body subluxation may be missed on axial CT images, these facet-dislocation patterns should be recognized by identifying the paired superior and inferior facets and establishing their congruency. Identification of the facets is accomplished by their orientation with respect to the vertebral body (superior facets are directed posteromedially and inferior facets are directed anterolaterally) as well as by the shape of the articular surface (superior facet articular surface is concave, inferior facet articular surface is flat or convex).

Fractures, Bone↗
PubMed1987

Non-Hodgkin's lymphoma of the head and neck: CT evaluation of nodal and extranodal sites.

Forty-five patients with non-Hodgkin's lymphoma (NHL) of the extracranial head and neck who had undergone CT as part of their evaluation were reviewed to assess the impact of CT on clinical management. The sites of tumor deposition were subdivided by location: I, nodal; II, extranodal, lymphatic (Waldeyer's ring); and III, extranodal, extralymphatic (orbit, sinonasal, deep facial spaces, mandible, salivary gland, skin, and larynx). The CT appearance of NHL in each of the three locations was analyzed for characteristic CT signatures. Nodal NHL was suspected when CT showed multiple, large, homogeneous lymph nodes, often in unusual nodal chains of the head and neck. Extranodal, lymphatic NHL of Waldeyer's ring was indistinguishable from squamous cell carcinoma of this area unless synchronous tumor deposit in an extranodal, extralymphatic location was also present. When NHL was in nodes and/or Waldeyer's ring, CT-derived information was of limited clinical value since treatment was unfocused (chemotherapy and/or large-field radiotherapy). The CT appearances of extranodal, extralymphatic NHL was generally not distinguishable from other malignancies of these areas. However, CT-derived information regarding deep-tissue tumor size and extent was critical to planning the radiotherapy ports.

Adult↗
PubMed1986

The tailored CT evaluation of persistent facial nerve paralysis.

The clinical, radiographic, and pathologic records of 39 patients with peripheral facial nerve dysfunction seen from October 1981 through July 1984 are reviewed. The extent of preradiologic clinical localization of suspected lesions and their subsequent pathologic confirmation is correlated to the number, sequence, and type of radiographic evaluations performed.

Adolescent↗
PubMed1985

Extracalvarial soft tissues in cranial computed tomography. Normal anatomy and pathology.

Computed tomography has emerged as the modality of choice for imaging soft tissues of the face and neck. However, the extracalvarial soft tissue anatomy has not been delineated. The CT appearance of normal anatomy and variants, including the cutaneous and subcutaneous tissues, muscle layers, and subgaleal space is described. A pathologic spectrum that includes congenital, inflammatory, traumatic, and neoplastic lesions is presented. When appropriate CT windows for viewing the extracalvarial soft tissues are utilized, significant clinical information may be provided.

Adolescent↗
PubMed1985

Digital angiography: matched filtration versus mask-mode subtraction.

Matched filtration was compared to mask-mode subtraction in patients undergoing routine intravenous digital subtraction angiography. Images were analyzed for noise and edge sharpness, and the two techniques were compared subjectively by three radiologists. The quantitative results indicated that matched filtration increased the signal-to-noise ratio by an average of 2.23 but did not significantly increase vessel blurring. Subjectively, the observers favored matched filtration over mask-mode subtraction for overall image quality in 26 out of 30 cases (p less than 0.005) in terms of both sharpness and freedom from motion artifacts.

Angiography↗
PubMed1985

Peripheral facial nerve dysfunction: CT evaluation.

Peripheral facial nerve dysfunction may have a clinically apparent or occult cause. We reviewed the clinical and radiographic records of 36 patients with peripheral facial nerve dysfunction to obtain information on the location of the suspected lesion and the number, sequence, and type of radiographic evaluations performed. Inadequate clinical evaluations before computed tomography (CT) was done and unnecessary CT examinations were also noted. In those patients in whom the cause of peripheral facial nerve dysfunction is apparent, the clinical-radiographic workup is self-evident. When the cause of dysfunction is occult, however, a tailored CT examination should be done based on a thorough clinical evaluation. We have suggested a practical clinical and radiographic scheme to evaluate progressive peripheral facial dysfunction with no apparent cause. If this scheme is applied, unnecessary radiologic tests and delays in diagnosis and treatment may be avoided.

Adolescent↗
PubMed1985

Supratentorial ependymoma: CT appearance.

The computed tomographic appearances of 22 biopsy-proved supratentorial ependymomas were analyzed. Supratentorial ependymomas were usually intraparenchymal, larger than 4 cm, and cystic. Contrast enhancement was moderate to intense, with homogeneous or ring-enhancement patterns commonly seen. Intratumoral calcification was present in one-third of the cases, while hydrocephalus and peritumoral edema were seen in 50%. Intratumoral hemorrhage was not a characteristic of the lesion. In contrast to cellular ependymomas, malignant ependymomas and ependymoblastomas demonstrate higher attenuation prior to administration of contrast material, more intense enhancement, lower frequency of calcification within the tumor, and less distinct margination.

Adolescent↗
PubMed1985

Infection and tumor of the masticator space: CT evaluation.

The masticator space is a distinct deep facial space, bounded by the superficial layer of deep cervical fascia and containing the four muscles of mastication and the ramus and posterior body of the mandible. Trismus often complicates evaluation of masticator space disease. However, computed tomography (CT) clearly delineates the normal and pathologic anatomy of this region. The CT appearance of the masticator space was demonstrated in a retrospective review of 32 patients with either infection or tumor involving this space. Masticator space infections were found to have characteristic CT appearances and patterns of spread. CT was especially useful in differentiating inflammation from frank abscess, detecting mandibular osteomyelitis, and directing surgical drainage to the precise deep-tissue space involved. In cases of tumor, the primary utility of CT was in defining tumor extent accurately and in helping to assess resectability and determine radiation therapy ports.

Abscess↗
PubMed1984

Lumbar spine: pretest predictability of CT findings.

Demographic and symptomatic data gathered from 460 patients referred for lumbosacral CT examinations were analyzed to determine if the prescan probability of normal or abnormal findings could be predicted accurately. We were unable to predict the presence of herniated disk on the basis of patient-supplied data alone. Age was the single most significant predictor of an abnormality and was sharply related to degenerative disease and spinal stenosis.

Adult↗
PubMed1983

Computed tomography and differential diagnosis of the extruded lumbar disc.

Herniated lumbar discs may infrequently extrude through or around the posterior longitudinal ligament and migrate within the epidural space either as a contiguous mass with or as a free fragment of the parent nucleus pulposus. Recognition of this entity may obviate the use of chymopapain or may otherwise alter the surgeon's approach to the disc herniation. The CT scans of 40 surgically confirmed cases of lumbar disc extrusion were reviewed. In 36 cases CT identified the extruded disc material as a lobulated soft tissue mass of similar attenuation to the disc space, migrating either superiorly or inferiorly from the parent disc interspace. In 34 cases the extrusion was 6 mm or more from the center of the parent disc. Calcification of the disc extrusion occurred in five cases. In six cases an extruded free fragment of disc material was associated with a normal-appearing parent disc interspace at CT. In one such case gas bubbles occurred within a degenerating extruded fragment which had eroded through the dura. The differential diagnosis of lumbar disc extrusion is also discussed.

Adult↗
PubMed1982

Computed tomographic evaluation of corpus callosum agenesis and associated malformations.

Agenesis of the corpus callosum is not an uncommon congenital malformation in neurologically symptomatic children. The computed tomographic scan characteristics of uncomplicated agenesis of the corpus callosum include: (a) widely separated parallel or nonconverging lateral ventricles; (b) "Bat wing" or "bullhorn" appearance of the frontal horns; (c) High-riding third ventricle which may be enlarged and have a tear-drop or rhomboid appearance; and (d) Selective dilatation of the occipital horns occurs frequently. Associated malformations identifiable by computed tomographic scan include Dandy-Walker cysts, interhemispheric cysts, porencephaly, Arnold-Chiari II malformations, and skull deformities.

Abnormalities, Multiple↗