Biomedical subjects
Publications and source records attributed to R H Dorwart.
We describe two brothers with myotonic muscular dystrophy and intracranial arteriovenous malformations who developed acute vascular neurological syndromes. The simultaneous occurrence of these two disorders in brothers could either be due to chance association, or due to a common causative mechanism, possibly a membrane abnormality.
Computed tomography (CT) has become an important diagnostic modality in the evaluation of ocular and orbital disease. A weakness of CT, however, is its inability to show clearly intraocular lesions that do not contain calcium. These images can be improved by the careful selection of window width and window level and by the use of a technique known as "blinking." The use of these enhancement techniques is illustrated in two cases of leukocoria in children.
Because CT of spinal extraarachnoid metrizamide collections may be misleading, we reviewed the postmetrizamide CT scans of 425 patients in order to characterize the appearance of subdural or epidural metrizamide. Eight patients were found to have extraarachnoid metrizamide contrast collections. In all patients, both the subarachnoid space and the extraarachnoid collection were opacified with metrizamide. In seven patients, a subdural collection of metrizamide created a mass upon the opacified subarachnoid space. Three of these subdural collections were less dense than the opacified subarachnoid compartment and simulated soft-tissue disease, including tumor and an arteriovenous malformation. The hypodense collections are probably a result of leakage of metrizamide and cerebrospinal fluid through the spinal needle defect. CT clues for diagnosing these potentially misleading subdural collections include preservation of the normal dural and epidural interface, identification of small islands of metrizamide within a suspected soft-tissue "mass," the presence of concomitant epidural contrast material collections, and the absence of adjacent vertebral-body destruction.
CT has proved to be an excellent method of studying the spine in cross section. The osseous axial skeleton may be imaged without the need for contrast media. Analysis of the contents of the spinal canal requires administration of intrathecal contrast material, except in the lumbar region, where epidural fat serves as a natural contrast agent. This article illustrates and discusses normal axial CT anatomy of the spine.
Computed tomography is an extremely valuable adjunct to the evaluation of the cervical spine and spinal cord. When combined with intrathecal metrizamide enhancement and with computer reformatted images in sagittal and coronal planes, CT is a thorough diagnostic modality that can be applied to congenital/developmental, degenerative, and trauma-induced abnormalities. Its major deficiency is the potential to miss defects that are oriented in the transverse plane because of partial volume averaging of adjacent surrounding bone. CT scanning of the cervical spine has been used sparingly to date, probably because available scanners are used for higher-priority demands. However, anecdotal information in the literature document the value of CT in evaluations of the cervical spine, intervertebral disks, neural foramina, and spinal cord. In the future, magnetic resonance scanners may shift some of the imaging burden away from x-ray CT. More widespread use of CT for evaluation of cervical radiculopathies and myelopathy may then occur.
Quantitative perimetric studies in two women, each 52 years of age, with involvement of the lateral geniculate nucleus (caused by a small arteriovenous malformation in one and by an astrocytoma in the other) disclosed a striking wedge-shaped horizontal sectoranopia that was perfectly congruous in one case and incongruous in the other. Selective interruption of the dual blood supply to the lateral geniculate nucleus (with the anterior choroidal artery supplying the anterior hilus, together with the anterior and lateral nucleus and the lateral choroidal artery supplying the remainder of the nucleus) may result in a congruous visual field defect with steeply sloping borders because such a lesion must respect the anatomic boundaries produced by this vascular supply. Partial infiltration or involvement of the lateral geniculate nucleus (where uncrossed retinal projections terminate in one group of laminae, while crossed retinal projections terminate in another) provides a logical explanation for the occurrence of incongruous visual field defects. This unusual horizontal wedge-shaped defect should suggest lateral geniculate nucleus involvement, especially in the absence of trauma.
The clinical, pathologic, and radiologic features of pigmented villonodular synovitis of large synovial joints are presented. The typical plain-film presentation of this unusual entity is a noncalcified capsular soft-tissue mass of the knee, without bony abnormalities. When pigmented villonodular synovitis occurs in other joints, it is often accompanied by cystic bone erosions. This important radiographic finding might mislead one to an improper diagnosis of neoplasia or infection. This review reveals insufficient emphasis in the radiologic literature on the high incidence of bone lesions in joints affected by pigmented villonodular synovitis. A mechanism for the development of bone cysts is proposed. Clinical, pathologic, radiologic, and therapeutic considerations are discussed.
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Normal cross-sectional anatomy and anatomical variants. Detailed line drawings of important features and images from a correlative CT/anatomical study of human cadaver spines will be included. The cross-sectional appearance of deviations from normal anatomy will also be demonstrated. Scanning techniques and methods of image recording. Patient processing efficiency and expeditious data recording and analysis will be stressed. The utility of multiplanar computer reformations will be discussed. Commonly encountered pathological conditions. Examples of intervertebral disc disease, spinal canal and lateral recess stenosis, facet arthropathy, trauma, infections, and neoplasms will be presented. A protocol for the use of intravenous and intrathecal contrast agents will be proposed.
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High resolution thin section axial CT scans (REVIEW reconstruction ARRANGE reformation--General Electric copyright were utilized to evaluate the petrous bone of 17 patients, ages 3 to 60, with congenital hearing loss. Two scanning protocols were evaluated: 1.5 mm thick sections at 1.5 mm intervals, and 1.5 mm thick sections at 1.0 mm intervals. These protocols were qualitatively compared with regard to 1. visualization of small anatomical structures, and 2. computer reformatted images in coronal and sagittal planes. Our experience suggests this imaging capability is highly useful in th evaluation of congenital ear abnormalities. Seventeen patients were examined with high resolution CT scans. The inner ear abnormalities included varying degrees of Mondini's dysplasia. The large vestibule, the large fenestra into the internal auditory canal, as well as the poor cochlear formation, were seen in these malformations. These studies have allowed a greater degree of accuracy in counseling parents of patients with inner ear malformations. Middle and external ear deformities were also encountered. The imaging technique is capable of demonstrating ossicular deformities, as well as the nature of canal atresias. It is particularly useful in the planning of surgery on some of these patients in that location of the plane of the facial nerve canal can be determined prior to surgery. This provides the ability to determine whether surgery is possible, and if so, the probability of opening the middle ear adequately to obtain appropriate reconstruction. Illustrative cases demonstrate the ease of visualizing the small structures of the inner and middle ear and the ability to review these structures in any plane utilizing the ARRANGE program.
Three patients with optic tract lesions, incomplete homonymous hemianopias, and good vision in both eyes are presented. All three had a Marcus Gunn pupil in the eye with temporal field loss (eye contralateral to the tract lesion). This pupillary sign may serve to differentiate acute optic tract from acute geniculostriate lesions when the characteristic infrageniculate optic atrophy has not had time to develop.
Rupture of the Achilles tendon is an urgent but usually clinically apparent orthopedic problem. Repair must be made promptly for full recovery. A number of methods of radiographic evaluation have been proposed to confirm the diagnosis of Achilles rupture. This report describes a case in which magnetic resonance imaging provided exquisite definition of the injury to the Achilles tendon.
Heterotopia of the gray matter is a developmental malformation in which ectopic cortex is found in the white matter of the brain. A case of a 33-year-old man with cortical heterotopia who had a lifelong history of seizures and psychomotor retardation is reported, including the results of cerebral CT, magnetic resonance imaging, and positron emission tomography using 18F-2-deoxyglucose.
We studied the relationships between cerebral structure and function in 10 patients with complex partial seizures who had major cerebral lesions, including porencephalic cysts, tuberose sclerosis, agenesis of the corpus callosum, and cerebral hemiatrophy. Evaluation included computed tomography (CT) and magnetic resonance imaging (MRI) scanning, EEG, and positron emission tomography (PET) using [18F]-2-deoxyglucose. Surface EEG usually showed widespread, bilateral epileptiform discharges even if pathology was clearly restricted to one hemisphere. In several cases, interictal PET hypometabolism was more widespread than structural changes seen on CT and MRI, extending to involve the ipsilateral temporal lobe in patients with extratemporal lesions. This study shows that patterns of metabolic and electrophysiologic dysfunction may not be predicted by structural lesions in patients with partial seizure disorders.
Three children with histopathologically diagnosed sclerosing endophthalmitis presumably secondary to Toxocara canis were studied by orbital computed tomography. The diffuse increased intraocular density present in the CT scans was indistinguishable from that observed in Coats's disease and non-calcifying retinoblastoma. Although retinoblastoma constitutes the major life-threatening cause of leukocoria in children, a number of other simulating conditions (pseudoglioma) can cause diagnostic confusion. In some cases of leukocoria it is exceedingly difficult to exclude the possibility of retinoblastoma without having to resort to enucleation. The availability of new non-invasive tests may make the distinction between retinoblastoma and pseudogliomas more easily attainable. Computed tomography (CT) has been shown to be of particular value in this regard by demonstrating intraocular calcification within retinoblastoma and rarely in lesions that stimulate it. CT may also be used to more appropriately plan therapy for children with retinoblastoma by assessing the status of the optic nerve and orbit. The exact role of CT in the evaluation of children with leukocoria, however, has not been completely established, since the computed tomographic features of several lesions that simulate retinoblastoma have not been described. The three most common causes of pseudoglioma are persistent hyperplastic primary vitreous, Coats's disease and sclerosing endophthalmitis. The latter entity when associated with a characteristic granulomatous inflammation is considered to represent the sequela of Toxocara canis infection of the eye. This report describes the computed tomographic findings in three cases of histologically diagnosed sclerosing endophthalmitis, presumably due to Toxocara canis.
Computed tomography (CT) constitutes a major advance in noninvasive diagnostic investigation of children with leukokoria , especially where media opacities preclude adequate visualization of the posterior segment, and, performed in conjunction with other studies such as diagnostic ultrasonography, has significantly improved diagnostic accuracy. Although retinoblastoma, the commonest life-threatening cause of leukokoria , usually presents with characteristic CT findings of intraocular calcification, during extraocular extension, the orbital portions of the tumor are non-calcific and contrast dramatically with the intraocular portion. Currently CT is also the best available technique for diagnosis of trilateral retinoblastoma. Computed tomographic features of several types of pseudogliomas (a collective term for lesions commonly mistaken for retinoblastomas) are also discussed with histopathologic correlation. In persistent hyperplastic primary vitreous, a conical density in CT corresponded to detached and dysplastic retina. A high density layered opacity corresponded to subretinal blood. In Coats' disease and sclerosing endophthalmitis homogenous intraocular CT density corresponds to vitreous and subretinal exudates radiologically indistinguishable from non-calcific retinoblastoma. Long-standing retinal detachments in children occasionally presenting with leukokoria showed subtle homogenous intraocular densities on CT.