Search PubMed⌕ Search

Biomedical subjects

R A Hyman

Publications and source records attributed to R A Hyman.

At least 19 recordsLinked to original sources
PubMed1990

Far lateral lumbar disc herniations and associated structural abnormalities. An evaluation in 60 patients of the comparative value of CT, MRI, and myelo-CT in diagnosis and management.

The management of 60 patients with far lateral lumbar disc herniations operated on over a 5-year period are presented. These lesions were located superiorly within the neural foramens beneath or distal to the facet joints. The type of surgery performed in 43 of 60 (72%) of these patients was significantly altered by the presence of diffuse and lateral recess stenosis. This was better appreciated on the myelogram and myelo-CT (M-CT) studies than with the noncontrast CT and MRI examinations alone. Myelo-CT findings were particularly valuable in assessing patients who had previous surgical procedures.

Female↗
PubMed1990

Intraocular radiation blocking.

Iodine-based liquid radiographic contrast agents were placed in normal and tumor-bearing (Greene strain) rabbit eyes to evaluate their ability to block iodine-125 radiation. This experiment required the procedures of tumor implantation, vitrectomy, air-fluid exchange, and 125I plaque and thermoluminescent dosimetry (TLD) chip implantation. The authors quantified the amount of radiation attenuation provided by intraocularly placed contrast agents with in vivo dosimetry. After intraocular insertion of a blocking agent or sham blocker (saline) insertion, episcleral 125I plaques were placed across the eye from episcleral TLD dosimeters. This showed that radiation attenuation occurred after blocker insertion compared with the saline controls. Then computed tomographic imaging techniques were used to describe the relatively rapid transit time of the aqueous-based iohexol compared with the slow transit time of the oil-like iophendylate. Lastly, seven nontumor-bearing eyes were primarily examined for blocking agent-related ocular toxicity. Although it was noted that iophendylate induced intraocular inflammation and retinal degeneration, all iohexol-treated eyes were similar to the control eyes at 7 and 31 days of follow-up. Although our study suggests that intraocular radiopaque materials can be used to shield normal ocular structures during 125I plaque irradiation, a mechanism to keep these materials from exiting the eye must be devised before clinical application.

Animals↗
PubMed1989

Computed tomography versus magnetic resonance imaging of the brain. A collaborative interinstitutional study.

A retrospective study (1983-1984) of magnetic resonance imaging (MRI) and computed tomography (CT) examinations in 471 patients with known pathology in the brain and craniocervical junction was conducted in order to determine the relative efficacy of MRI versus CT. All MRI examinations involved slice thickness greater than 10 mm, and only single-slice single-echo or multislice single-echo imaging techniques were available. These studies were evaluated independently by two neuroradiologists from a panel of six for anatomic abnormalities, lesion contrast, and radiologist's impression. Results, which excluded microadenomas of the pituitary and approximately 9% of studies in which consensus was not achieved by the readers, were as follows: (1) 14% of the studies were positive on MRI but normal on CT; (2) in 55% of the studies, MRI was better than CT; (3) MRI was equal or better than CT in 95% of the studies; and (4) CT was better than MRI in 5% (21/421) of the examinations. There were no patients in this series where CT was positive but MRI missed the abnormality.

Adult↗
PubMed1989

Aneurysms and vascular malformations.

Intracranial aneurysms and vascular malformations are frequently detected following intracranial hemorrhages. A CT scan is the most sensitive method of detecting acute subarachnoid, parenchymal, and intraventricular hemorrhages. Small aneurysms are inconsistently visualized on MR scans. Angiography remains the standard for complete and accurate depiction of patent aneurysms, as well as of arteriovenous and venous malformations that have not thrombosed. Giant and thrombosed aneurysms present as mass lesions and are frequently detected when MR is used as a screening examination. Often MRI characterizes these lesions better than CT or angiography. Patients with vascular malformations who have focal neurologic symptoms without hemorrhage are best evaluated with MRI. Patent vascular malformations demonstrating flow void and other flow-related phenomena are readily demonstrated. Occult vascular malformations, including thrombosed arteriovenous, venous, and cavernous malformations and telangiectasia, are also best detected by MRI and are not visible on angiography.

Cerebral Angiography↗
PubMed1988

Imaging strategies for MR of the brain.

MR has emerged as the imaging modality of choice for the brain in patients presenting with seizures, chronic headaches, progressive neurologic deficits, ataxia, vertigo, hearing loss, visual loss, congenital abnormalities, signs of increased intracranial pressure, dementia, suspected multiple sclerosis, and in the vast majority of other elective neurologic problems. CT should currently be considered the primary imaging modality in patients with acute neurologic deficits (stroke), acute onset of severe headaches, and when fine bone detail is required. Acutely injured patients are more readily studied with CT. The vast majority of patients in whom CT is preferred are seen in emergent situations, frequently in hospital emergency rooms. The effects of trauma beyond the acute stage are best evaluated with MR. In the future, MR is likely to become the procedure of choice in even more clinical situations than at present. A summary of currently recommended primary imaging modalities in various clinical situations is provided in Table 1.

Ataxia↗
PubMed1988

Imaging strategies for MR of the spine.

Magnetic resonance (MR) imaging has rapidly evolved as a primary modality for evaluating the spine. Following routine radiographs, MR is currently the preferred examination in evaluating patients presenting with myelopathy, suspected congenital abnormalities, discitis/osteomyelitis, and myeloradiculopathy. It is becoming the examination of choice in evaluating patients with radiculopathy as well when fast-scan techniques are available. MR of the spine will prove increasingly important as the technology advances. It is likely that MR will replace myelography entirely for many indications.

Humans↗
PubMed1985

0.6 T magnetic resonance imaging of the orbit.

Magnetic resonance (MR) imaging of the orbit was performed with a 0.6 T superconducting imaging system in 100 patients with normal orbits who were being evaluated for brain pathology and in 21 additional patients with a variety of orbital lesions to determine the efficacy of MR imaging in displaying orbital abnormalities. Usually, MR studies were performed using a multislice technique with multiple spin-echo pulse sequences and 30, 60, and 90 msec echo times and 500, 1500, and 2000 msec repetition times. Using section thicknesses of about 8 mm, imaging was performed in the transaxial, coronal, and sagittal projections. Pixel size was 0.9 X 1.8 mm, and the examination took about 30 min. The MR findings were compared with computed tomographic (CT) findings in all cases. Either combined axial and coronal studies of 5-mm-thick sections or a thin axial study of 1-mm-thick sections followed by reformatting techniques to obtain multiplanar images was used. Contrast enhancement was used in the CT studies. Both MR and CT clearly demonstrated the soft-tissue abnormality in all cases except two, in which MR failed to detect the abnormality. In one, MR failed to detect a small retrobulbar hemorrhage that occurred after a surgical procedure for retinal detachment. In the second case, rather extensive calcification in the posterior choroidal layers and lens was not detected by MR imaging. In several other cases, MR provided information beyond that obtained with CT. MR has the advantage of providing exquisite anatomic detail in multiplanar images, and it appears to be more sensitive than CT in detecting small, subacute and chronic hemorrhage within soft-tissue masses in the orbit and in detecting ischemia of the globe. CT is superior to MR imaging in portraying fine bone detail.

Adult↗
PubMed1979

Computed tomography: regression of periventricular enhancing lesions in multiple sclerosis.

A patient with two periventricular enhancing lesions on computed tomography subsequently demonstrated clearing of these abnormalities without treatment and a clinical course compatible with multiple sclerosis. CT scans obtained in disease processes associated with acute demyelination and alteration of the blood-brain barrier can show enhancing lesions. These lesions can initially be confused with primary or secondary neoplasms, enhancing infarcts or arteriovenous malformation. The differential diagnosis of enhancing lesions without significant mass effect should initially include the acute phase of multiple sclerosis and other demyelinating processes.

Adult↗
PubMed1979

The big rib sign: localization of basal pulmonary pathology in lateral projection utilizing differential magnification of the two hemithoraces.

Basal pulmonary pathology which silhouettes the hemidiaphragm in lateral view may not be detectable in routine postero-anterior projection. In such cases, correct lateralization of pathology to the left or right hemithorax depends on accurate identification of the silhouetted left and right hemidiaphragm in lateral view. A prospective analysis of the sensitivity and accuracy of five techniques for identifying the left and right hemidiaphragms in more than 100 patients revealed that the most accurate method for lateralizing juxtadiaphragmatic pathology was the "big rib" sign, a technique based upon the relative difference in magnification between the left and right ribs. Techniques based upon the visceral gas bubble or upon obscuration of the anterior portion of the left hemidiaphragm by the heart proved less useful. Techniques based upon the position and configuration of the major fissures or upon higher and lower position of the two hemidiaphragms were ineffective.

Adult↗
PubMed1979

Cervical myelopathy caused by developmental stenosis of the spinal canal.

The authors present six patients with myelopathy caused by developmental stenosis of the cervical spine. Hyperextension injuries precipitated the onset of symptoms in two patients, aged 19 and 20 years. In four, 41 to 69 years of age, symptoms were gradual in onset, progressing to severe disability. X-ray films revealed narrowing of the dorsoventral diameter of the spinal canal to as little as 1.0 cm. The myelograms showed widening of the cord in the transverse plane strongly suggestive of an intramedullary tumor. A unique finding was maldevelopment with flattening of the neural arch often hidden by the posterior portions of the articular facets when seen in the lateral views. These patients showed no significant evidence of spondylosis, arthrosis, or any of the structural stigmata usually observed in cervical spondylotic myelopathy. When indicated, decompressive laminectomy is the treatment of choice.

Adult↗
PubMed1978

Computed tomographic evaluation of therapeutically induced changes in primary and secondary brain tumors.

A prospective study was initiated to evaluate computed tomography as a method for monitoring therapeutically induced changes in brain tumors. Early postoperative scans may be misleading in the evaluation of residual tumor because of trauma to the blood-brain barrier during operation. The size of the dominant mass (17/25), enhancement (11/25), edema (11/25), and ventricular distortion (14/25) were decreased in many patients after radiation therapy. Occasional tumors increased in size during radiation therapy (3/25). Enlargement of the lateral ventricles developed in 9 of 25 patients. Computed tomography offers definite advantages over nuclide brain scans, angiography and other diagnostic studies for evaluating therapeutically induced changes in brain tumors.

Brain Neoplasms↗
PubMed1978

The origin of the left gastric artery.

Five hundred celiac angiograms were reviewed to evaluate the frequency of clinically significant variations in the origin of the left gastric artery. In 13 of 500 cases, the left gastric artery arose anomalously most often as a direct branch of the aorta; in 14 of 500 cases, the left gastric artery primarily supplied the liver with only minor contributions to the stomach. An aberrant origin of the left gastric artery necessarily influences the angiographic diagnosis and therapy of gastrointestinal hemorrhage.

Angiography↗
PubMed1977

Endocystography in cystic neurilemmoma.

During myelographic evaluation for a suspected herniated disc, a cystic neurilemmoma in the lower lumbar region was inadvertently punctured and a contrast study of the interior of the lesion resulted. The possibility of puncture of a cystic mass should be considered in the differential diagnosis when a complete block is encountered above and below the site of needle puncutre, and particularly when the contrast column demonstrates a relatively smooth biconcave appearance.

Cysts↗