Search PubMed⌕ Search

Biomedical subjects

N Patronas

Publications and source records attributed to N Patronas.

53 records · Page 3Linked to original sources
PubMed1988

Computed tomography and magnetic resonance imaging in adult-onset leukodystrophy.

Five clinically affected and nine at-risk members of a kindred with an autosomal dominant adult-onset leukodystrophy simulating chronic progressive multiple sclerosis were studied with computed tomography (CT) and magnetic resonance imaging (MRI). Computed tomographic scans showed white matter lucencies occurring earliest and most prominently in the frontoparietal region. The lesions were nondiscrete, diffuse, and bilaterally symmetric. These changes were more clearly visualized as areas of increased signal intensity with T2-weighted MRI. Magnetic resonance imaging also showed increased signal intensity in the brain stem, cerebellar white matter, or both of four patients. Both MRI and CT differentiated this entity from multiple sclerosis, but MRI was superior to CT in detailing the extent of white matter involvement.

Adult↗
PubMed1988

Hemispheric asymmetries, fourth ventricular size, and cerebellar morphology in autism.

Hemispheric asymmetries, fourth ventricular size, and cerebellar morphology were examined in 15 healthy men, aged 18 to 39 years, with documented childhood diagnoses of infantile autism, and in 20 healthy age- and sex-matched controls using computerized transverse axial tomography (CT). Nine patients were of approximately average intelligence, 3 showed specific language impairments, and 3 were mentally retarded. No significant group differences were seen in the distributions of frontal or posterior asymmetries of width or petalia. No subject showed evidence of cerebellar atrophy or an enlarged fourth ventricle. These results fail to support a hypothesis of unusual hemispheric asymmetry or macroscopic abnormalities of the posterior fossa in autism.

Adolescent↗
PubMed1988

Magnetic resonance imaging of cerebral lesions in patients with the Sjögren syndrome.

Thirty-eight patients with the primary Sjögren syndrome, 16 with active neuropsychiatric manifestations and 22 without clinical evidence of central nervous system involvement had magnetic resonance (MR) imaging. Eight patients had focal neurologic deficits (6 of these also had psychiatric, or cognitive dysfunction), and 8 had psychiatric or cognitive abnormalities alone. Magnetic resonance imaging showed abnormal results in 12 of 16 (75%; 95% CI, 48 to 93) patients with active central nervous system disease (67 focal lesions predominantly within the subcortical and periventricular white matter), and in 2 of 22 (9%; 95% CI, 1 to 29) patients without clinical evidence of central nervous system disease (P less than 0.0001). Seven of eight patients with focal neurologic deficits and 5 of 8 patients with psychiatric or cognitive dysfunction alone had abnormal results on MR imaging. Magnetic resonance imaging was more sensitive in the subgroup with focal deficits, (sensitivity, 88%; 95% CI, 44 to 97) than computerized axial tomography or cerebral angiography. Magnetic resonance imaging detects focal cerebral lesions in patients with the Sjögren syndrome and central nervous system involvement, including patients with psychiatric and cognitive dysfunction alone.

Adult↗
PubMed1987

Cerebral glucose metabolism in the Lennox-Gastaut syndrome.

We used positron emission tomography with fluorine 18-labeled 2-deoxyglucose to study cerebral glucose metabolism in 10 patients with Lennox-Gastaut syndrome who had normal neuroradiological studies. The scans showed decreased metabolic rates relative both to those in the caudate nucleus and to normal control values in 3 patients whose seizures began before the age of 1, as well as in a patient with hyperprolinemia. No patient had a region of persistent focal hypometabolism. Metabolic rates increased in parallel with increased electroencephalographic discharges in 1 patient; 3 patients had lower metabolic rates when the electroencephalogram showed epileptiform discharges and while the patients were taking barbiturates.

Adolescent↗
PubMed1986

Amenorrhea-galactorrhea due to occult hypothyroidism.

A 25-year-old woman with galactorrhea, oligomenorrhea, hyperprolactinemia, and CT evidence of pituitary enlargement had transsphenoidal microsurgery with initial resolution of hyperprolactinemia, but persistent oligomenorrhea and galactorrhea. In retrospect, she had biochemical evidence of primary hypothyroidism before operation, despite being clinically euthyroid. Administration of thyroid hormone resulted in resolution of the pituitary enlargement and the symptoms.

Adult↗
PubMed1985

Positron emission tomography in generalized seizures.

We used 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) to study nine patients with clinical absence or generalized seizures. One patient had only absence seizures, two had only generalized tonic-clonic seizures, and six had both seizure types. Interictal scans in eight failed to reveal focal or lateralized hypometabolism. No apparent abnormalities were noted. Two patients had PET scans after isotope injection during hyperventilation-induced generalized spike-wave discharges. Diffusely increased metabolic rates were found in one compared with an interictal scan, and in another compared with control values. Another patient had FDG injected during absence status: EEG showed generalized spike-wave discharges (during which she was unresponsive) intermixed with slow activity accompanied by confusion. Metabolic rates were decreased, compared with the interictal scan, throughout both cortical and subcortical structures. Interictal PET did not detect specific anatomic regions responsible for absence seizure onset in any patient, but the results of the ictal scans did suggest that pathophysiologic differences exist between absence status and single absence attacks.

Adult↗
PubMed1984

Hereditary adult-onset leukodystrophy simulating chronic progressive multiple sclerosis.

We studied a large kindred with a chronic progressive neurologic disorder affecting at least 10 men and 11 women in four generations in a pattern compatible with autosomal dominant inheritance. In 20 of the affected subjects, evaluated before the availability of computerized tomography and without regard to family history, the diagnosis was multiple sclerosis. Symptoms of the neurologic disorder begin in the fourth and fifth decades and include cerebellar, pyramidal, and autonomic abnormalities. The autonomic symptoms, which involve bowel and bladder regulation and orthostatic hypotension, may be the earliest changes but are frequently disregarded. Survival for 20 years after onset is common. The CT scan is striking and shows a symmetrical decrease in white-matter density, beginning in the frontal lobes but extending to all of the centrum ovale and the cerebellar white matter. Limited pathological observation reveals gross white-matter degeneration with microscopic vacuolation, preservation of U fibers and cortical structures, and no inflammatory changes or reactive gliosis. Because of its hereditary basis, the disorder should be susceptible to genetic definition and ultimately to treatment or prevention.

Adult↗
PubMed1984

Fetal hydrocephalus. II. Amelioration of fetal porencephaly by in utero therapy in nonhuman primates.

The postnatal course of a form of infantile porencephaly under pressure in monkeys was evaluated by comparing brain development between animals that had received the hydrocephalic antenatal vent for intrauterine treatment and those that had not been treated antenatally. Brain development was assessed by computed tomographic scans. The studies showed asymmetric malformations and associated porencephalic lesions in infant monkeys not treated in utero, despite installation of a conventional postnatal ventriculoperitoneal shunt. In contrast, apparently normal development of brain tissue in infants given intrauterine therapy was observed.

Amnion↗
PubMed1984

The role of positron emission tomography in the evaluation of seizure disorders.

We studied patients with partial and primary generalized seizures using fluorine-18-labeled 2-fluorodeoxyglucose and positron emission tomography. Interictal studies of patients with partial seizures showed regions of focal or lateralized hypometabolism in 15 of 17 patients with unilateral electroencephalographic foci. Several patients had more than one hypometabolic region. In 1 patient PET hypometabolism was contralateral to the electroencephalographic epileptic focus. Six of 10 patients without definite electroencephalographic foci also showed unilateral PET hypometabolic regions. PET during complex partial seizures in 3 patients showed hypermetabolism at the site of the hypometabolic focus. A postictal scan in 1 patient showed extension of interictal temporal hypometabolism to the frontal lobe as well. Interictal scans in 8 patients with primary generalized seizures did not reveal any hypometabolic regions. One patient scanned during an attack of absence status epilepticus showed a slight decrease in metabolic rate compared to the interictal scan. Temporal lobectomy has been performed in 6 patients with focal PET hypometabolism. PET may obviate the need for depth electrode study in some patients with intractable partial seizures.

Electroencephalography↗
PubMed1984

A study of computer-assisted tomography. I. The incidence of positive CAT scans in an asymptomatic group of patients.

In order to study the type and number of CAT scan abnormalities of the lumbar spine that occur in asymptomatic people, 52 studies from a control population with no history of back trouble were mixed randomly with six scans from patients with surgically proven spinal disease, and all were interpreted by three neuroradiologists in a blinded fashion. Irrespective of age, 35.4% (26.6%, 51.0%, and 31.3%) were found to be abnormal. Spinal disease was identified in an average of 19.5% (23.8%, 22.7%, and 12.5%) of the under 40-year-olds, and it was a herniated nucleus pulposus in every instance. In the over 40-year-old age group, there was an average of 50% (29.2%, 81.5%, and 48.1%) abnormal findings, with diagnoses of herniated disc, facet degeneration, and stenosis occurring most frequently.

Adult↗
PubMed1983

EEG, transmission computed tomography, and positron emission tomography with fluorodeoxyglucose 18F. Their use in adults with gliomas.

We evaluated the relationship between findings from EEG, transmission computed tomography (CT), and positron emission tomography in 23 adults with gliomas. The cortical metabolic rate was suppressed in patients with and without focal slowing. Focal delta activity was not related to involvement of gray or white matter. Rhythmic delta activity and focal attenuation of background amplitude on EEG, however, were correlated with involvement of the thalamus.

Adult↗
PubMed1983

[18F]fluorodeoxyglucose positron emission tomography in refractory complex partial seizures.

Positron emission tomography with simultaneous electroencephalographic monitoring was performed with [18F]fluorodeoxyglucose in 20 patients with complex partial seizures who had normal computed tomographic scans. Seven patients had only unilateral epileptiform discharges on the electroencephalogram, 3 had predominantly unilateral discharges, and 10 had nonlocalized epileptiform abnormalities. Positron emission tomography showed a hypometabolic lesion in 16 of the 20 patients. Pathological changes in the hypometabolic region were found in postoperative specimens in 4 of 5 patients studied. Positron emission tomography was unaffected by the seizure frequency, state of alertness, or number of spike discharges during the scan. There was a tendency for patients to have higher overall metabolic rates when taking less medication. Seizures occurring during [18F]fluorodeoxyglucose uptake in 3 patients produced a hypermetabolic area at the interictal hypometabolic focus. Positron emission tomography sometimes showed more widespread hypometabolism than suspected on the basis of the scalp-recorded electroencephalogram. The frontal lobe showed a greater degree of hypometabolism than the temporal lobe in 3 patients. Focal lesions may be identified by positron emission tomography even if the electroencephalographic abnormality is not well localized.

Adult↗
PubMedDate not supplied

The quantitative relation between T1-weighted and T2-weighted MRI of normal gray matter and iron concentration.

A retrospective analysis of 158 T1-weighted and T2-weighted MRI scans of normal brains at 0.5 and 1.5 Tesla was performed. Signal intensities in the frontal cortex, caudate nucleus, putamen, and globus pallidus were divided by those of frontal white matter; and these gray/white ratios were correlated with iron concentration, estimated from the anatomical region and age of the patient. Intraregional plots were also made of gray/white ratio versus age for the 1.5 Tesla scans. The changes in both T1-weighted and T2-weighted ratios were consistent with the hypothesis that 1/T1 and 1/T2 vary linearly with iron concentration, and the corresponding coefficients, determined separately from the interregional and intraregional plots, were generally in agreement. Furthermore, the variability of the MRI ratios at 1.5 Tesla was consistent with expected iron variability except for the cortex, in which partial volume errors due to sulci and white matter caused increased variations. The MRI results agreed well with in vitro data on T1 and T2 in tissue specimens and with other MRI studies. When compared with T1 and T2 in ferritin solution, a significant "tissue relaxation enhancement" was found, attributable to slower diffusion and clustering of ferritin in tissue.

Adult↗
PubMedDate not supplied

Experimental comparison of EOE-13 and perfluoroctylbromide for the CT detection of hepatic metastases.

The relative advantages of EOE-13 and perfluoroctylbromide (PFOB) as contrast agents were evaluated using CT scanning in animals with implanted liver tumors. Three criteria were used to compare these compounds: (1)the density difference between liver and tumor, (2)the presence of opacification of intrahepatic vascular structures, and (3)the presence of ring enhancement around the tumors. All three radiographic features were superior in the scans after injection of 5 g/kg of PFOB. When a reduced dose (1.7 g/kg) of PFOB was used, however, the scans obtained with EOE-13 were of approximately equal quality. It is concluded that if toxicity problems prevent administration of PFOB in humans, then EOE-13 will probably remain the contrast agent of choice for tumor imaging in the liver.

Animals↗
PubMedDate not supplied

MR imaging of cerebral hematomas at different field strengths: theory and applications.

Existing theory on relaxation effects in blood and their field dependence is related to magnetic resonance (MR) imaging of hematomas. These effects include (a) relaxation caused by protein and other macromolecules; (b) inhomogeneous susceptibility created by paramagnetic forms of hemoglobin (Hb) (deoxy and met) within the red blood cells; and (c) direct interaction of water protons with paramagnetic metHb. The effect of proton density is also discussed. These effects combine in a complex way to create hypo- or hyper-intensity on MR images of hematomas. Further, the effects change as the hematoma evolves both physically and chemically. In particular, there are five stages that are associated with typical image appearance: (a) oxygenated blood; (b) deoxygenated blood; (c) conversion to metHb; (d) hemolysis; and (e) protein resorption.

Cerebral Hemorrhage↗
PubMedDate not supplied

MR color mapping of myelin fiber orientation.

Diffusion of water in brain white matter has been shown to be anisotropic: Water mobility is lower when measured perpendicular to the fiber direction rather than parallel to it. This feature was used to produce images of the myelin fiber orientation. Coronal and sagittal MR diffusion images were obtained in volunteers using an echo-planar imaging sequence sensitized to molecular diffusion in perpendicular directions. Color-coded images of myelin orientation were then generated by combining these images together. The orientation of the white matter tracts was found to be in excellent agreement with known anatomy. Myelin fiber orientation mapping may offer a new perspective to evaluate white matter disorders.

Algorithms↗