Biomedical subjects
M H Gado
Publications and source records attributed to M H Gado.
Position of cerebellar tonsils in the normal population and in patients with Chiari malformation: a quantitative approach with MR imaging.
Magnetic resonance imaging was used to define quantitatively the position of the cerebellar tonsils in the normal population and in patients with Chiari malformations. The average distance of the tonsillar tips from the foramen magnum was 2.9 +/- 3.4 mm above the foramen in 82 subjects without posterior fossa abnormality or increased intracranial pressure, and 10.3 +/- 4.6 mm below the foramen in 13 patients with Chiari malformations (p less than 0.005). Consequently, extension of the tonsils below the foramen magnum is considered normal up to 3 mm, borderline between 3 and 5 mm, and clearly pathologic when it exceeds 5 mm.
Leigh disease (subacute necrotizing encephalomyelopathy): CT and MR in five cases.
Magnetic resonance (MR) imaging and CT were used in supporting the diagnosis of Leigh disease (subacute necrotizing encephalomyelopathy) in five patients. Two cases were confirmed at postmortem examination, and three patients have laboratory and/or clinical histories suggestive of Leigh disease. Four cases demonstrated findings in the basal ganglia, especially the putamina, with symmetrical areas of low attenuation on CT. Correspondingly, on proton saturation and T2-weighted pulse sequences, these areas showed high intensity signal characteristics by MR. Similar findings were noted in the caudate nucleus (two cases). Magnetic resonance proved to be superior to CT in establishing other areas of involvement: tectum and tegmentum (one case) and medullary olive (one case). Pathology identified these lesions as representing necrosis. Magnetic resonance may be diagnostic in the appropriate clinical setting.
Baboon basal ganglia stereotaxy using internal MRI landmarks: validation and application to PET imaging.
PURPOSE: We report the residual anatomic error after a nine parameter visually guided registration of MR images with a baboon brain atlas to validate a stereotactic method for use in PET studies. METHOD: MPRAGE images of brain in six baboons and one nemestrina monkey were placed in atlas space using internal landmarks and proportional measurements. An expert noted the location of 23 subcortical test points in the transformed images and in the atlas. RESULTS: The average absolute error at the test points was 1.62 mm. At the extremes of the brain surface, there was more variability. PET images could be combined across animals in a common atlas space. CONCLUSION: There is minimal subcortical error attributable to anatomic variability after this method of transforming MR images of baboon to stereotactic space. This method provides a useful tool for intrasubject PET baboon studies as well as "bootstrapping" for more refined methods.
Comparison of computerized tomography and radionuclide imaging in "stroke".
Forty patients were studied by computerized tomography and by radionuclide brain imaging. The final diagnosis was infarction in 29 patients, intracerebral hematoma in seven, acute SAH in one, and old cerebrovascular accidents in three. CT was far superior to RN in detecting intracerebral hematomas and distinguishing them from cerebral infarction. The results of CT and RN tests were comparable regarding the percentage of abnormalities. However, the results in the same patients were not identical in 55% of the cases, indicating a complementary role for the two tests. There was no relationship between the frequency of abnormalities on CT and the time lapse after the onset of cerebral infarction. RN uptake was not seen in patients with old cerebrovascular accidents.
Polytomographic delineation and variations of the vestibular aqueduct in adult humans.
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Three-dimensional display of intracranial soft-tissue structures.
Efficient three-dimensional surface reconstructions of intracranial bony, soft-tissue, and cerebrospinal fluid-filled structures have been created from serial narrowly collimated transaxial computed tomographic (CT) scans. These three-dimensional surface images are useful in visualizing the relations among intracranial details. Views may be produced in frontal, rear, 45 degrees oblique (anterior and posterior), top and bottom, and both lateral projections. This method has been applied to image the surface of intracranial structures by reformatting the images with elimination of the overlying bone. This method was realized as a computer program that operates on a conventional unmodified CT scanner without operator intervention.
Infected epidermoid cyst of the sphenoid bone.
An infected epidermoid cyst presented on CT as a primarily dense, sclerotic expansile lesion in the greater wing of the sphenoid bone. Presumably, infection was responsible for the atypical appearance.