The calcifications of Fahr disease that are detected by CT in the dentate nuclei of the cerebellum, basal ganglia, and white matter of the cerebral hemispheres displayed three patterns with magnetic resonance imaging using the multiple echo technique: (a) cerebellar calcifications were undetected; (b) basal ganglia calcifications displayed low or no signal and appeared as "black" areas in four echoes; and (c) white matter calcifications displayed a high signal in the four echoes and appeared intensely white. The different behavior of the three calcified sites probably reflects different stages of the disease or different metabolic states with predominance of inert calcium deposits in the basal ganglia. In the white matter there is probably a higher concentration of binding proteins and mucopolysaccharides.

Brain Diseases↗

PubMedDate not supplied

MR imaging of intradural extramedullary tumors of the cervical spine.

Magnetic resonance imaging was performed in eight patients with extramedullary cervical tumors; two were studied with a 0.15 T resistive system and six with a 0.5 superconductive unit. All tumors were verified surgically: Five meningiomas and three schwannomas were found. Magnetic resonance demonstrated the location and size of the tumors as well as their relationship with and mass effect on the adjacent spinal cord. Meningiomas showed a tendency to have relaxation times close to those of the normal parenchyma; in multiple echo sequences their signal tends to decay in a way similar to that of the spinal cord. The different signal from the surrounding cerebrospinal fluid sometimes provides a visual cleavage to define the extramedullary location of the neoplasm. Schwannomas and neurofibromas have a less constant behavior; their T2 relaxation time may be slightly longer than that of the spinal cord and the tumor may display a more intense signal in the T2 weighted images. Usually, however, the signal intensity of the extramedullary tumors is lower than that of the intramedullary.

Adolescent↗

PubMedDate not supplied

MRI, antibody-guided scintigraphy, and glucose metabolism in uveal melanoma.

To evaluate the usefulness of structural and biochemical imaging techniques for the diagnosis of uveal melanoma, 12 patients with choroidal melanoma were examined. Magnetic resonance imaging was used in 11 of 12 patients, as one had a metal prosthesis. All the subjects underwent single photon planar scintigraphy (SPPS) and single photon emission computed tomography (SPECT) using the 99mTc-labeled F(ab')2 of the anti-melanoma monoclonal antibody 225.28S ([99mTc]MoAb) and positron emission tomography (PET) using [18F]fluorodeoxyglucose ([18F]FDG). Magnetic resonance identified 6 of 11 melanotic lesions (definite melanomas) and 4 of 11 hypomelanotic lesions (probable melanomas), whereas in one case it was inconclusive. [99mTc]MoAb uptake was observed in 5 of 12 lesions using SPPS and 8 of 12 lesions using SPECT. [18F]FDG uptake was observed in 3 of 12 lesions by PET. These results demonstrate that both MR and radioimmunoscintigraphy are sensitive techniques for the diagnosis of choroidal melanomas and suggest that the detection of melanomas by MR, SPPS, and SPECT is largely dependent upon their size. The validity of these conclusions was verified in four subjects in whom the diagnosis was based on MR and/or SPECT findings only and confirmed by histology. The finding that only some of the uveal melanomas of larger size are visualized based on [18F]FDG uptake suggests that melanomas can have either high or low glucose consumption.

Choroid Neoplasms↗

PubMedDate not supplied

Modern imaging techniques in GH secretory disorders.

Magnetic resonance images of the pituitary-hypothalamic area in patients with GH secretory disorders, divided into two groups (hypersecretory and hyposecretory), were studied. In the first group there were 42 patients with pituitary adenoma; size, signal characteristics, direction of growth, and type of enhancement were analyzed and compared with similar studies in 40 age and sex matched control patients with non-GH secreting pituitary adenomas. No significant differences were found except for a higher frequency of chiasm involvement and a more pronounced contrast enhancement in the control group. The hyposecretory group was composed of 101 patients with congenital idiopathic growth hormone deficiency (CIGHD). MR revealed morphological abnormalities consisting of hypoplastic anterior pituitary and ectopic posterior pituitary (PPE) in 59 patients, without evidence of a complete pituitary stalk; in 42 patients the posterior pituitary was in normal position and the pituitary stalk visible. The group with PPE showed a greater frequency of multiple pituitary hormone deficiency (51% vs 12%), breech delivery (30% vs 7%) and associated congenital brain anomalies (12% vs 7%). These data suggest that CIGHD could be the result of a congenital midline brain anomaly in a significant proportion of patients.

Adenoma↗