Biomedical subjects

K Ericson

Publications and source records attributed to K Ericson.

106 records · Page 6Linked to original sources

PubMedDate not supplied

Positron emission tomography with ([11C]methyl)-L-methionine, [11C]D-glucose, and [68Ga]EDTA in supratentorial tumors.

Sixteen patients with supratentorial tumors were examined with positron emission tomography (PET) using [( 11C]methyl)-L-methionine, [11C]D-glucose, and [68Ga]EDTA as well as CT. There were nine astrocytomas (grade II), three oligoastrocytomas (grade II), two anaplastic astrocytomas (grade III), and two meningiomas. Six patients with low-grade astrocytomas and all three patients with oligoastrocytomas had an accumulation of [11C]methionine varying from slightly to intensely increased as compared with normal brain tissue. There was a markedly increased uptake of methionine in the anaplastic astrocytomas. Three of the low-grade astrocytomas had a decreased uptake of [11C]methionine in at least part of the tumor as compared with normal brain tissue. Contrast enhancement on CT or uptake of [68Ga]EDTA was not a prerequisite for increased accumulation of methionine. Uptake of [11C]glucose was lower than or equal to that of normal brain tissue in the low-grade tumors and also in one of the two anaplastic astrocytomas and in the bulk of the other. In each individual case the methionine uptake tended to be higher--or less decreased--than the glucose uptake. In the low-grade tumors the uptake of methionine and that of glucose were often different, occasionally markedly different, as far as the tumoral-peritumoral areas involved. These differences were even more remarkable in the two anaplastic astrocytomas. An increased uptake of methionine was often seen in areas appearing normal on CT. It appears that PET with [11C]glucose has limitations with regard to delineation of the low-grade astrocytomas, whereas PET with [11C]methionine usually better reflects the extent of these tumors and, to a lesser degree, the extent of the high-grade neoplasms. The results of PET with [68Ga]EDTA were similar to those with postcontrast CT in most patients. The two meningiomas exhibited a high uptake of all tracers used for PET as well as a marked contrast enhancement on CT. The extent of the meningiomas judged by PET with the various tracers correlated well with the extent assessed by postcontrast CT.

Adult↗

PubMedDate not supplied

PET study of methionine accumulation in glioma and normal brain tissue: competition with branched chain amino acids.

Five patients with glioma were examined with positron emission tomography using ([11C]methyl)-L-methionine. The study was repeated while the patient was being infused with branched chain amino acids (BCAA), 250 mumol/min. The accumulation rates of methionine in tumor tissue and in normal brain tissue were compared without and with the infusion of amino acids. Both tumor tissue and normal brain tissue showed a reduction in the methionine accumulation by 35% while the patient received the infusion. In one patient with a severe blood-tissue barrier disruption the tumor accumulation rate was unaffected. It is concluded that in gliomas without severe blood-tissue barrier disruption, the accumulation of methionine is governed by processes exhibiting similar properties regarding competition with BCAA as in normal brain tissue.

Amino Acids, Branched-Chain↗

PubMedDate not supplied

Recurrent tumor vs radiation effects after gamma knife radiosurgery of intracerebral metastases: diagnosis with PET-FDG.

OBJECTIVE: Our objective was to differentiate radiation effects from tumor progression in metastases stereotaxically irradiated with the multi-cobalt unit (Gamma Knife). MATERIALS AND METHODS: Eleven patients with stereotaxically irradiated cerebral metastases were examined with PET using [18F]fluorodeoxyglucose (FDG) to differentiate recurrent tumor from radiation effects. RESULTS: Six patients had increased uptake of FDG, and clinical, radiological, and pathological findings confirmed the diagnosis of recurrent metastases. These patients had an unfavorable prognosis and were all dead within 54 weeks after radiosurgery. Five patients had lesions without an increased accumulation of FDG. Four of these patients were alive after a total follow-up of 1.7 years, while one patient died of a peptic ulcer 56 weeks after radiosurgery. CONCLUSION: Positron emission tomography with FDG was of obvious prognostic value in this small series of patients and was clearly superior to CT and MR in the distinction between tumor recurrence and radiation effects (verified necrosis in one case).

Adult↗

PubMedDate not supplied

Cortical benzodiazepine receptor binding in patients with generalized and partial epilepsy.

Impaired cortical inhibition may be involved in epileptogenic mechanisms. In a positron-emission tomography (PET) study, we demonstrated a reduction of the cortical benzodiazepine (BZD) receptor density in the epileptic foci of patients with partial epileptic seizures. In the present study, we used the same method in 10 patients with primary generalized epilepsy to determine whether an altered BZD receptor binding could also be demonstrated in this patient group. The [11C]-labeled BZD receptor antagonist Ro 15-1788 was used as ligand. Receptor affinities and densities were calculated in various cortical regions and then compared with the values from corresponding "nonepileptic" regions in the previously examined partial epilepsy patients. Focal alterations of the BZD receptor density or affinity were not demonstrated in patients with generalized epilepsy. This patient group had a slight tendency toward lower mean cortical BZD receptor density, however, as compared with corresponding values from 10 patients with partial epilepsy. Our results strongly suggest that a focal alteration of cortical inhibition is not a prominent feature of human generalized epilepsy. The observed tendency toward lower mean cortical BZD receptor density may be a consequence of diffusely impaired cortical inhibition. Further investigations of this issue are therefore indicated.

Adult↗

PubMedDate not supplied

Fibromuscular dysplasia and the brain. I. Observations on angiographic, clinical and genetic characteristics.

The angiographic, clinical, and genetic characteristics of fibromuscular dysplasia (FMD) are reviewed in 37 patients (mean age 48 years) selected from a pool of 4000 angiograms of carotid or vertebral arteries. FMD was a neglected pathogenic factor in 28 patients with hemorrhagic or ischemic cerebral lesions. The aneurysms found in 19 patients had conventional appearance and were mainly located in the internal carotid or middle cerebral arteries and on the same side as the most affected cervical artery, which suggests that aneurysms and FMD are pathogenically related. A clinical syndrome is presented where headache, ECG-abnormalities, hypertension, mental distress, tinnitus, vertigo, arrhythmia, TIA, and syncope are frequent components. Hemicrania, sometimes combined with ipsilateral Horner's Syndrome, was found in patients with advanced lesions in the carotid artery of the same side. An associated occurrence of stroke in pedigrees, especially among young and middle aged females, indicates that FMD in the majority of cases in inherited as an autosomal dominant trait with reduced penetrance in males.

Adult↗

PubMedDate not supplied

Positron emission tomography of cavernous haemangiomas of the brain.

Four cases with lesions suspected to be low-grade intracerebral tumours but later proved to be cavernous haemangiomas are described. The patients were examined with contrast enhanced CT and with positron emission tomography (PET). The lesions were partly calcified with a mild or no mass effect and a slight contrast enhancement at CT. There were signs of disrupture of the blood-lesion barrier also on radionuclide studies. PET with 11C-methionine and 11C-glucose showed a normal or decreased accumulation of the tracers. This combination of findings has not been encountered in intracranial tumours. As a comparison, one case of glioblastoma is described. In this patient, the CT findings suggested a cavernous haemangioma. However, PET showed a markedly increased accumulation of 11C-methionine, which is compatible with brain tumour but not with haemangioma.

Adult↗

PubMedDate not supplied

Mobile intraventricular cyst of the third ventricle treated with stereotactic puncture. Report of a case.

A case of a pedunculated arachnoid cyst within the third ventricle is presented. The cyst was small so as not to appear as a significant expanding lesion on CT. The clinical history, however, suggested intermittent increase of the intracranial pressure. On CT there was some widening of the lateral and third ventricles, while the fourth ventricle had normal width. This finding in combination with the clinical history prompted further neuroradiologic examinations, including pneumoencephalography and ventriculography. The presence of a pedunculated mobile cystic lesion within the third ventricle was shown and its nature further elucidated by stereotactic puncture combined with contrast injection into the cyst. After emptying of the cyst, the patient has been free of symptoms during an observation time of 2 years. The diagnostic and differential diagnostic aspects are discussed and the value of traditional neuroradiologic methods emphasized.

Brain Diseases↗

PubMedDate not supplied

Stereotaxic angiography in gamma knife radiosurgery of intracranial arteriovenous malformations.

Gamma knife radiosurgery is an effective alternative to embolization or microsurgical removal of small arteriovenous malformations, particularly in eloquent areas of brain tissue. Stereotaxic angiography is a useful diagnostic and targeting adjunct to gamma knife radiosurgery, and the authors present their experience (1,100 patients) with methods and technique, and show how the nidus of the arteriovenous malformation can be defined angiographically. Dose planning employing digitization of the subtraction image enables determination of the spatial coordinates of the lesion by means of an interactive computer program.

Cerebral Angiography↗

PubMedDate not supplied

Positron emission tomography compared with magnetic resonance imaging and computed tomography in supratentorial gliomas using multiple stereotactic biopsies as reference.

Ten patients with findings at computed tomography (CT) suggesting intracranial supratentorial glioma were investigated to compare the diagnostic efficacy of this technique with that of positron emission tomography (PET) using 11C-methionine and examinations with magnetic resonance (MR). The findings were related to histopathologic examination of serial stereotactic biopsies, which were guided by the appearance of the lesions on PET examination. To obtain corresponding slice orientation with the different examination techniques, an individually shaped helmet fixation was used. However, in 3 cases this fixation device could not be used for MR. Histopathologic diagnosis, obtained in all cases from multiple target stereotactic biopsies, included glioma in 9 patients and reactive gliosis in one case. A detailed comparison of the three imaging techniques and the findings at stereotactic biopsies was possible in 7 patients, while in 3 patients comparison with MR was less exact due to the patient's refusal to wear the helmet during this examination. MR was the most accurate method for outlining the total extent of a lesion, i.e. the tumor and the edema surrounding it. Four lesions had homogeneous signal characteristics and in 6 lesions two (or more) compartments could be distinguished with MR. In 5 cases the MR findings were in complete agreement with the histopathologic findings. However, a thorough correlation between signal characteristics and histology was not possible. Using PET the occurrence and the extent of tumor tissue was correctly predicted in 7 patients. The PET was normal in one case. Findings at CT were in agreement with the histopathologic diagnosis in 5 patients. MR was the most sensitive method for the detection of lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Comparison of the accumulation kinetics of L-(methyl-11C)-methionine and D-(methyl-11C)-methionine in brain tumors studied with positron emission tomography.

Five patients with glioma were examined with positron emission tomography after the administration of 11C-L-methionine and at a following day with 11C-D-methionine. The rates of accumulation of the tracers were determined in the tumor and in the normal brain tissue according to a graphical technique of Patlak et coll. The accumulation rates for L-methionine were on the average 2.4 times higher than those of D-methionine in the tumors. The corresponding ration for normal brain tissue was 2.3. It is concluded that in this group of tumors without obvious blood-tumor-barrier breakdown, a stereospecific process with similar properties as in the normal brain tissue, is responsible for the accumulation of the labelled methionine.

Astrocytoma↗

PubMedDate not supplied

Application of a kinetic model on the methionine accumulation in intracranial tumours studied with positron emission tomography.

Eleven patients were studied with positron emission tomography (PET) using 11C-methionine. They all had low-grade astrocytomas (Kernohan grade II). The PET studies were analyzed with a metabolic model to obtain values for the influx, the accumulation rate and the partition coefficient of methionine in normal and tumourous tissue. Seven of the tumours showed an increased accumulation of methionine as compared with normal tissue on the static PET scans and also had higher values as to the kinetic parameters. Four tumours had a methionine accumulation equal to or lower than that of normal tissue and the kinetic parameters were also lower. Application of the kinetic model did not aid significantly in the delineation of the tumours. There was a correlation between the three parameters indicating an adaptation of the transport of methionine to the regional metabolic demand. The accumulation rate for normal cortical tissue was 0.49 nmol/g/min, the influx 0.97 nmol/ml and the partition coefficient 0.45 ml/g. These values are considerably higher than those previously reported. The differences might be attributed to differences in the corrections introduced for i.a. the occurrence of labelled metabolites in serum. With the use of a kinetic model, more information about the tracer is utilized and gained compared with the previously used graphic approach.

Brain Neoplasms↗

PubMedDate not supplied

Computed tomography of the brain in cases with venous vasculitis compared with an age-matched reference group.

Patients with a particular, steroid-sensitive headache and often characteristic pathology at orbital phlebography, have been suggested to suffer from venous vasculitis. Fifty such patients were examined with computed tomography (CT) of the brain. The findings were compared with those of an age-matched reference group selected at random to represent normal subjects. The CT examinations were analyzed with respect to size of lateral ventricles and signs of atrophy. In both groups, there was a significant increase of atrophy with age. There was also a significantly higher degree of atrophy in the patient group as compared with the reference group. The findings indicate that the supposedly underlying venous vasculitis is related to early aging and atrophy of the brain.

Adult↗

PubMedDate not supplied

Orbital phlebography for differentiation between multiple sclerosis and venous vasculitis in subacute blindness.

Thirteen consecutive patients with subacute unilateral loss of vision and periorbital pain but without pathology of the fundus or increased erythrocyte sedimentation rate, were investigated with visual evoked response, electrophoresis of serum and cerebrospinal fluid, and orbital phlebography. Seven of these patients were found to suffer from multiple sclerosis. The remaining 6 were considered to have venous vasculitis. There was a spontaneous recovery from visual impairment in all patients with multiple sclerosis, but not in patients with venous vasculitis. Of the latter patients, only two, who were treated with steroids within the first four days after onset of symptoms, regained vision. It appears that orbital phlebography is the diagnostic procedure of choice for proper management of patients with subacute loss of vision.

Adult↗

PubMedDate not supplied

PET studies of glucose metabolism in patients with schizophrenia.

The hypothesis of abnormal patterns of metabolism in schizophrenia was examined in a series of six young patients with psychotic symptoms satisfying the research diagnostic criteria. After intravenous injection of 11C-glucose obtained through a photosynthetic process, the regional activity of 11C in brain was measured with a four-ring positron camera. Regions of interest were obtained from computed tomographic images. Each patient underwent a second positron emission tomographic examinations after 4-5 weeks of treatment with a neuroleptic drug. No evidence of a hypofrontal pattern was found, but after treatment there was a reduced frontal uptake on the left side compared with temporal regions. The left-right asymmetry in the lentiform nucleus was reduced after treatment.

Acute Disease↗

PubMedDate not supplied

Comparative double-blind investigation of meglumine metrizoate, metrizamide, and iohexol in carotid angiography.

The new nonionic contrast medium iohexol (Omnipaque) was compared with its predecessor metrizamide (Amipaque) and with the conventional ionic medium meglumine metrizoate (Isopaque Cerebral) in carotid angiography using a double-blind crossover technique. The results indicated that iohexol and metrizamide caused less discomfort than the ionic medium. The circulatory effects of the three media were generally mild, and the diagnostic effectiveness was comparable when the iodine concentration was kept in the range of 280-300 mg I/ml.

Adolescent↗

PubMedDate not supplied

Computed orbital phlebography of the cavernous sinuses.

Computed orbital phlebography (COP), described as computed tomography with concomitant injection of contrast medium into a frontal vein, was used to evaluate the cavernous sinuses in 19 patients with intrasellar or parasellar lesions and in two normal controls. Bilateral opacification occurred in 12 subjects, eight of whom had pituitary tumors. Unilateral partial obliteration was encountered in four subjects, all of whom had pituitary tumors with marked parasellar extension. In three subjects with parasellar tumors, ipsilateral total obliteration of the cavernous sinus was seen. In one subject with no sign of parasellar tumor, there was no opacification of the cavernous sinuses, a failure attributed to technical factors. In one other subject, the frontal vein puncture was unsuccessful and COP could not be performed.

Cavernous Sinus↗