Biomedical subjects
Publications and source records attributed to N E Leeds.
The computed tomographic (CT) findings in two patients in whom intracranial granulocytic sarcomas preceded the onset of systemic myelogenous leukemia are presented. On CT, granulocytic sarcomas may be indistinguishable from meningiomas and difficult to differentiate from primary central nervous system malignant lymphoma and eosinophilic granuloma.
Cysticercosis is a parasitic infestation that commonly affects the central nervous system. This is a report of computed tomography findings in a patient with a noncalcified cyst causing asymmetric lateral ventricular obstruction at the foramen of Monro. The lesion was isodense and uniformly enhancing, an unusual finding possibly related to presentation early in the course of the disease. This disease should be considered in the differential diagnosis of the lesions at the foramen of Monro in patients with appropriate residence or travel history.
Eight patients with Herpes simplex encephalitis had computed cranial tomography (CT). In every case, areas of decreased attenuation were found in the temporal lobe(s); these areas extended to the insular cortex and often to the frontal or parietal lobes. This change developed between the third and the eleventh day of illness. It was present, sometimes only in retrospect, in patients who were alert as well as patients who were comatose. Compared to the isotopic brain scan, electroencephalogram, and cerebral angiogram, CT demonstrates changes that are indicative of H simplex early enough in the course of the illness to be therapeutically useful.
Four patients with well documented Reye syndrome were examined with noncontrast computed tomography. Acute findings are those of diffuse cerebral edema with low density in deep white matter, increased gray-white matter differentiation, and evidence of secondary ventricular compression. The diffuse nature of the changes is unlike the more focal pattern often seen in true viral encephalitis. Residual changes after severe diseases are those of nonspecific cerebral degeneration and are most pronounced in the frontal lobes. Atrophic ventricular dilatation was observed in two cases. Computed tomography findings correlate with all known pathologic studies and with the subsequent clinical courses in the patients examined.
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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.
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Intravenous administration of iodinated contrast agents permits identification of the major cerebral arteries and veins; third, fourth, and lateral ventricular choroid plexuses; falx and tentorium on appropriate sections of contrast-enhanced computed axial tomographic (CECT) images. Combinations of these normal vascular structures into conglomerate densities may produce confusing contrast pseudotumors on CECT images.
Forty-seven patients with a final diagnosis of brain metastases were studied with both computed tomography (CT) and radionuclide (RN) scanning. Fifty-three percent of these patients also underwent contrast enhanced CT. Radionuclide scanning detected 94% of the cases, while CT without contrast enhancement was positive in 89%. The addition of contrast material to the CT examination increased the total sensitivity of CT to 94% and permitted the detection of two cases that were falsely negative on RN scanning and CT without contrast. With both techniques, lesions in the cerebral hemispheres were detected more readily than infratentorial lesions. Radionuclide scanning was less sensitive than CT without contrast in the detection of multiple metastases. Contrast enhanced CT should be used in all cases of suspected cerebral metastases unless contraindicated.
Seven cases of ring blush following spontaneous and post-traumatic, subacute and chronic intracerebral hematoma are presented. As such a hematoma ages, a ring blush may be seen following contrast-agent enhancement. Serial CT demonstrates disappearance of the ring blush from two to six months after the first scan. The CT appearance of the ring blush is not specific for hematoma, but its peripheral location and lack of mass effect may be considered suggestive of hematoma with appropriate clinical findings. The characteristic serial changes permit correct diagnosis without surgical intervention in most cases.
Three extra-axial posterior fossa epidermoid tumors manifested nearly identical CT appearance of large size, sharp margination, apparently homogeneously increased attenuation in the range of 80-120 Hounsfield units, and absence of contrast-agent enhancement. This constellation of findings is distinctly different from that reported previously, and appears to be characteristic for some epidermoid tumors.
Fibromuscular dysplasia (FMD) of the intracranial internal carotid and vertebro-basilar system is extremely rare. A case with diffuse intracranial involvement and an associated carotid-cavernous fistula is presented. The literature is reviewed and the pathogenesis of this complication of FMD is discussed.
Bands of increased density representing the free edges and lateral margins of the tentorium were routinely identified on 100 sequential, normal, contrast-enhanced axial CT scans of good quality. Because the tentorium has a complex shape, the exact configuration of these bands varies with the level and the angle of the CT section. Comparison of CT scans with anatomic specimens permits an understanding of these varying configurations, and provides a means to estimate the position of the tentorium on non-contrast CT studies. The CT manifestations of diverse non-neoplastic diseases including subarachnoid hemorrhage, arteriovenous malformation, venous sinus thrombosis and Dandy-Walker malformation may be understood, in part, in terms of the configuration and density of these tentorial bands.
Most juxtatentorial lesions may be localized accurately on contrast-enhanced axial section CT scans by use of the opacified tentorial bands. Lesions that lie lateral edge of the diverging bands are supratentorial. Lesions that lie medial to the V-shaped tentorial bands are infratentorial and/or incisural. Flattening of the tentorial border of a lesion helps to identify its location. Use of the tentorial bands identifies transincisural extension of meningioma reliably, but does distinguish well between true transtentorial growth of meningioma and marked upward bulging of the tentorium from purely infratentorial meningioma.
Nine cases of brain abscess, five of subdural empyema, and one of epidural empyema with associated subdural empyema were identified using computed tomography (CT). Smal and multiple abscesses as well as unilateral, bilateral, and parafalcine empyemas were detected. These lesions were demonstrated rapidly and accurately, even in areas that are demonstrated poorly by other diagnostic techniques. No false-negative studies were found in cases of brain abscess or subdural empyema. However, since the appearance of brain abscesses of CT scans is similar to that of neoplastic and vascular lesions, false-positive reports of brain abscess were encountered.
Thirteen patients with subdural empyema underwent arteriography preoperatively and three were restudied postoperatively. Arterial vascular changes were found in nine cases and consisted of localized or diffuse arterial irregularities. In two cases the arterial changes resolved with effective therapy. These arterial changes are similar in appearance and response to therapy to those noted with meningitis; however, in this series they were shown to have occured in seven cases with subdural empyema but without associated meningitis. Therefore, empyema alone may cause localized or diffuse arterial irregularities.
A case of associated calvarial and cervical spine lesions in sarcoidosis is reported. The radiographic findings are discussed and the literature is reviewed.