Biomedical subjects
Publications and source records attributed to M D Deck.
3 children were found to have small focal calcifications on computerized tomography. These lesions ultimately proved to be malignant gliomas in 2 children, and a mixed glioma in the third. Focal calcification on CT scans may pose a diagnostic dilemma for the clinician, and these patients should be carefully followed as possible early brain tumors.
Seven patients with cancer complicated by nonmetastatic sagittal sinus thrombosis were encountered in a 7-year period. Five had hematologic malignancies and two had solid tumors. There were two different presentations. In the first, neurologic signs and symptoms (e.g., headaches, seizures, hemiparesis, lethargy) occurred suddenly in five patients shortly after initiation of cancer therapy. Four of these five patients recovered with minimal residua; the fifth died as a direct result of the sinus thrombosis. The second presentation occurred in the two patients with terminal cancer who declined gradually without focal signs; both patients died. Only arteriography can reliably establish the diagnosis of sagittal sinus occlusion. In patients with cancer, sagittal sinus occlusion probably results from a "hypercoagulable state" associated with the systemic neoplasm.
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A clinical or subclinical leukoencephalopathy occurs in some children after treatment of acute lymphatic leukemia with prophylactic cranial radiation therapy and parenteral or intrathecal methotrexate. We have observed a similar clinical leukoencephalopathy in patients with bone tumors treated with intravenous high-dose methotrexate and citrovorum factor without cranial irradiation. CT scans of such patients may indicate decreased white matter attenuation, but visual appraisal of this phenomenon is occasionally misleading. A computerized method for analyzing white matter hypodensity by determining the mean attenuation coefficient for one or several contiguous CT slices has therefore been developed. Serial comparisons of this mean attenuation coefficient appear to be more reliable than simple visual appraisal.
The accurate determination of ventricular volume from computed tomography (CT) is not a trivial problem. The direct approach of measuring the area within a visually determined boundary or contour level and multiplying by the nominal slice thickness may be subject to large errors because such boundaries are not, in general, well defined. When the ventricles are filled with a high-contrast material such as metrizamide, we may use the technique of 'partial volume summation,' a simple but accurate, clinically applicable method which may be performed on a standard DeltaScan-50 or similar system.
Volume averaging, relatively slight differences in the mean attenuation coefficients of CSF and white/grey matter, and the irregular contours of the human ventricular system have so far seriously limited the accuracy of CT estimation of ventricular volume. Taking advantage of the high attenuation of metrizamide-containing CSF, we have developed three methods for computing ventricular volume after metrizamide CT ventriculography; these methods depend upon computer analysis of X-ray absorption data obtained from contiguous CT brain slices. All three methods were validated by CT scanning a formalin-fixed cadaver brain containing an apoxy-resin cast of the ventricular system. Calculated ventricular volumes were compared with the actual measured volume of the ventricular cast.
Metrizamide was injected into the ventricular system of three adults and five children with indwelling ventricular catheters and subcutaneous CSF reservoirs. A first-order rate constant, k, for metrizamide washout from one lateral ventricle was determined with reference to ventricular metrizamide concentration on serial (up to six) postinjection CT scans. Lateral ventricular volume, Vv, was estimated after metrizamide injection by a planimetric method and by partial volume analysis, an interactive computerized technique. The rate of lateral ventricular CSF formation, If, was calculated as k X Vv and ranged from 0.0622 to 0.103 ml/min. Precise measurements of lateral ventricular CSF bulk flow depend upon adequate mixing of the injected contrast material with ventricular CSF and accurate measurements of lateral ventricular volume.
In a patient with left glomus jugulare tumor and left hypoglossal nerve palsy, computed tomography demonstrated focal lucency of the left half of the tongue. This was interpreted to represent postdenervation fibrosis and fatty replacement of the intrinsic and extrinsic lingual muscles supplied by the hypoglossal (XIIth cranial) nerve.
We have examined 6 patients with delayed cerebral necrosis following irradiation of extracranial neoplasms. Four of the 6 patients received 1,760 rets (or less) tumor dose. The initial symptoms attributable to radiation necrosis appeared 4 to 31 months after irradiation and were those of a focal supratentorial mass. Cerebral angiography delineated an avascular frontal or temporal lesion in all 6 patients; in 1 case a magnification study revealed narrowing, irregularity, and occlusion of small cortical vessels. Four of our 6 patients underwent craniotomy with partial or complete surgical extirpation of necrotic brain tissue. Two operated patients are alive and without disabling neurological symptoms 30 and 25 months, respectively, after the operation. The characteristic neuropathological features of delayed radiation necrosis of brain suggest that vascular injury rather than neuronal or glial damage is of primary pathogenetic significance.
Metrizamide, a nonionic, water-soluble contrast agent, was injected into the ventricular system of 3 patients with indwelling ventricular catheters and subcutaneous cerebrospinal fluid reservoirs. A first-order rate constant, k, for metrizamide washout from the right lateral ventricle was determined with reference to mean ventricular metrizamide concentration on serial CAT scans; right ventricular volume, V, was estimated after metrizamide injection by multiplying the appropriate ventricular area on consecutive CAT slices by the nominal slice thickness. The rate of right lateral ventricular CSF formation, If, in our 3 patients was calculated as k X V and ranged from 0.083 to 0.103 ml per minute.
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The reasons for radiologic evaluation of patients with cerebrovascular accidents, or strokes, and transient ischemic attacks are (1) to demonstrate surgically correctable vascular lesions and intracerebral masses due to hematomas and (2) when necessary, to confirm a diagnosis of atherosclerotic brain disease and rule out the presence of such conditions as subdural hematoma, aneurysm, arteriovenous malformation, or tumor. The radiologic techniques available include plain skull radiography, ultrasound, radionuclide scanning, computerized transaxial tomography (CTT), and cerebral angiography.
Computed tomography has been found to be a more accurate diagnostic tool in the analysis of brain metastases than radionuclide scanning. Of 1,100 patients studied by CT scan, 57 showed evidence of intracerebral metastasis, and 14 showed evidence of hydrocephalus. Density levels below that of normal brain tissue were found in cases of metastases from the lung (13), breast (7), melanoma (4), kidney (3), lymphoma (3), and nasopharynx (1); levels above normal were found in cases of metastases from melanoma (8), lung (3), colon (3), chorionic carcinoma (2), osteogenic sarcoma (1), and kidney (1).
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