PubMed Health⌕ Search

Biomedical subjects

W A Cohen

Publications and source records attributed to W A Cohen.

14 recordsLinked to original sources
PubMed1992

Brain SPECT and the effect of cerebral angioplasty in delayed ischemia due to vasospasm.

Cerebral vasospasm is a major determinant of outcome after subarachnoid hemorrhage (SAH). Brain SPECT with 99mTc-HMPAO was obtained before and after cerebral angioplasty in 10 patients with delayed ischemia due to vasospasm. Eight patients had clinically evident neurologic improvement after the procedure. Visual interpretation and an internal-reference (cerebellum), manual, semi-quantitative region of interest (ROI) analysis revealed improvement of regional cerebral blood flow (rCBF) in 9 out of 10. There were disagreements between the visual and ROI analysis in the two that did not improve clinically. For all 10, the average increase per anterior circulation vessel dilated (n = 17) was 8.8% by comparison of the corticocerebellar ratios. For the eight that improved, the average increase was 10.5%. Brain SPECT is valuable for evaluating delayed cerebral ischemia caused by vasospasm after SAH and is useful to document the changes in rCBF induced by angioplasty. It is possible that SPECT may be useful to detect critical reductions in perfusion before clinical deficits develop, thereby offering the potential to identify candidates for early treatment with angioplasty.

Adult↗
PubMed1990

Correlation of motor cortex brain mapping data with magnetic resonance imaging.

Brain maps derived intraoperatively from patients undergoing tumor resection were correlated retrospectively with magnetic resonance (MR) images with respect to the precise localization of the motor cortex in an attempt to identify useful preoperative MR imaging landmarks that correspond to functional brain regions. Superior axial T2-weighted MR images consistently localized the central sulcus, whereas parasagittal and farlateral sagittal images readily identified the rolandic (sensorimotor) cortex, as a functional unit, based on the cingulate-marginal sulcus and insula, respectively. It is therefore concluded that multiplanar MR images may serve as a useful preoperative planning aid prior to removing intrinsic brain tumors within or adjacent to the motor cortex.

Brain Mapping↗
PubMed1988

Benign lymphoepithelial parotid cysts and hyperplastic cervical adenopathy in AIDS-risk patients: a new CT appearance.

The contrast material-enhanced computed tomographic (CT) scans of 18 patients at risk for acquired immunodeficiency syndrome (AIDS) who had painless facial swelling were reviewed. All scans demonstrated parotid cysts and diffuse homogeneous cervical adenopathy. The cysts were bilateral in all but three cases. Eleven of 13 patients tested had antibodies to the human immunodeficiency virus (HIV), and two of the five untested patients later developed AIDS. The authors believe that the CT findings of multiple parotid cysts and cervical adenopathy suggest that the patient may be infected with the HIV virus, and the radiologist should alert the referring physician so that appropriate precautions and treatment may be initiated.

AIDS-Related Complex↗
PubMed1987

Pitfalls in the CT diagnosis of atlantoaxial rotary subluxation.

CT was used to examine six patients with clinically evident atlantoaxial rotary fixation, two patients with torticollis, and six normal subjects who had turned their heads to the side as far as voluntarily possible. The CT appearances of the atlantoaxial complex were identical in all three groups. To differentiate these groups, we propose a functional scan through C1-C2 in which patients are scanned initially as they present, with their heads fixed in lateral rotation. Subsequent scans are obtained with their heads turned to the maximum contralateral rotation. CT scans in patients with atlantoaxial rotary fixation demonstrate no motion at C1-C2 during this maneuver, while those in patients with transient torticollis show a reduction or reversal of the rotation of C1 on C2.

Adolescent↗
PubMed1985

The "hyperacute" extraaxial intracranial hematoma: computed tomographic findings and clinical significance.

Thirteen patients with acute subdural and epidural hematomas were found to have fresh, unclotted blood at the time of surgical decompression several hours after injury. Computed tomographic (CT) scans of these patients demonstrated areas of hyperdensity, corresponding to clotted hematoma, admixed with areas of isodensity, corresponding to liquid blood. Active bleeding from identifiable loci was found in 11 patients, 4 of whom had massive hemorrhages. Clotting abnormalities ranging from slightly elevated laboratory test results to a full-blown clinical picture of disseminated intravascular coagulation occurred in 8 patients. We describe the CT pictures of these "hyperacute" lesions, and we postulate that such CT presentations indicate either the presence of ongoing active intracranial bleeding or the onset of a coagulopathy complicating the management of these lesions.

Adolescent↗
PubMed1982

Dynamic CT scanning for visualization of the parasellar carotid arteries.

Evaluation of patients before transsphenoidal hypophysectomy for large intrasellar mass lesions has required bilateral internal carotid artery angiography. Using intravenous injection of contrast medium, a method has been developed to visualize the parasellar carotid arteries with rapid sequence sequential computed tomographic scanning. In 18 patients, the cavernous segments of the internal carotid arteries were well seen in 27 of 28 instances with technically complete examinations. The vascularity of the mass lesions and vascular encasement was also demonstrated.

Adenoma↗
PubMed1982

Giant intracranial aneurysms: rapid sequential computed tomography.

Giant intracranial aneurysms often present as mass lesions rather than with subarachnoid hemorrhage. Routine computed tomographic (CT) scans with contrast material will generally detect them, but erroneous diagnosis of basal meningioma is possible. Rapid sequential scanning (dynamic CT) after bolus injection of 40 ml of Renografin-76 can conclusively demonstrate an intracranial aneurysm, differentiating it from other lesions by transit-time analysis of the passage of contrast medium. In five patients, the dynamics of contrast bolus transit in aneurysms were consistently different from the dynamics in pituitary tumors, craniopharyngiomas, and meningiomas, thereby allowing a specific diagnosis. Dynamic CT was also useful after treatment of the aneurysms by carotid artery ligation and may be used as an alternative to angiographic evaluation in determining luminal patency or thrombosis.

Carotid Arteries↗
PubMed1982

The value of dynamic scanning.

Dynamic CT is a proven alternative to angiography in the assessment of parasellar lesions. Characteristics of the tumor, such as vascularity or cystic regeneration, are easily demonstrated. Dynamic CT is able to diagnose conclusively an intracranial aneurysm and to follow the therapeutic course after ligation of the carotid artery. The application of dynamic CT to cerebrovascular disease is limited by the lack of subsecond sequencing in fragmentation scans. Its importance in documenting the patency of the cervical internal carotid artery that appears to be occluded angiographically cannot be overstressed.

Adult↗
PubMedDate not supplied

Spinal cord compression induced by steroid therapy: CT findings.

Long-term steroid therapy has many well documented complications. Both epidural fat deposition and vertebral compression fractures are among such complications. We report two cases in which acute paraplegia occurred following compression fracture without retropulsion of bone fragments or significant narrowing of the spinal canal. However, both patients had abnormally large epidural fat deposits as an underlying and contributing condition. Therapy to relieve the compression was disappointing.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Supratentorial and spinal cord hemangioblastomas: gadolinium enhanced MR appearance with pathologic correlation.

A case is presented that illustrates the magnetic resonance appearance of supratentorial hemangioblastomas both prior to and following intravenous administration of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). Spinal cord hemangioblastomas were also present and were visualized only after Gd-DTPA administration. Pathological verification of the multiple tumoral lesions was obtained.

Adult↗
PubMedDate not supplied

Prospective cerebral MR study of HIV seropositive and seronegative men: correlation of MR findings with neurologic, neuropsychologic, and cerebrospinal fluid analysis.

PURPOSE: As part of a longitudinal study of human immunodeficiency virus type 1 (HIV) infection, we attempted to identify early cerebral MR findings that might correlate to clinical evidence of central nervous system involvement. METHODS: We studied 65 seropositive and 40 seronegative homosexual males using cranial MR, neurologic, immunologic, and neuropsychologic examinations. RESULTS: The incidence of mildly enlarged ventricles, sulci, and punctate areas of abnormal signal in both groups was similar in both groups. Diffuse, poorly defined areas of abnormal white matter signal were difficult to consistently identify in seropositives. Enlarged adenoidal lymphoid tissue was found in 30 (46%) of seropositives and 2 (5%) of seronegatives (P = .0001). The incidence of sinus inflammatory change was similar in the two groups. CONCLUSION: MR of intracranial contents is substantially normal in a non-AIDS HIV(+) population.

Adult↗
PubMedDate not supplied

Posttraumatic syrinx formation: experimental study.

An experimental study was performed to examine posttraumatic spinal cord cavitation in an animal model by evaluating immediate and delayed computed tomographic (CT) scans obtained after administration of intrathecal contrast material. Four cats underwent midthoracic laminectomy and spinal cord contusion using a standard 400 g-cm model. All animals were studied by CT with intrathecal contrast enhancement before and 4-5 days, 3-4 weeks, and 7-13 weeks after experimental cord contusion. Either metrizamide or iopamidol was used as the contrast agent. Two of the four cats had CT and pathologic evidence of cord cavitation at the site of injury. Another animal had uptake of contrast material into the spinal cord without pathologic evidence of cyst formation, which was believed to represent malacic change. The fourth animal had a normal-appearing cord by both CT and pathologic criteria. Animals that received metrizamide after cord contusion had generalized myoclonic seizures. This did not occur when iopamidol was administered.

Animals↗
PubMedDate not supplied

Imaging factors influencing spine and cord measurements by CT: a phantom study.

Metrizamide computed tomography (CT) of the spine allows evaluation of the contents and measurement of the size of intracanalicular structures. The relative size (linear and area measurements) of spinal structures can be changed by varying imaging factors or the density of intrathecal contrast material. Two phantoms, one consisting of rods embedded in a plastic cylinder and the other of a vertebral body with a central rod simulating spinal cord, were evaluated with varying imaging factors (window width and window level) and different contrast concentrations within the surround. It was found that wide window widths allowed the most consistent measurements independent of window level, that a window level midway between the CT number of rod and surround would facilitate uniform measurements independent of window width, and that the use of high concentrations of contrast material (high CT number) in the surround, in combination with a wide window width, was most effective in establishing consistent measurements.

Humans↗